Design of High-performance Wearable Energy and Sensor Electronics

Subscriber access provided by University of South Dakota

Functional Inorganic Materials and Devices

Design of High-performance Wearable Energy and Sensor Electronics from Fiber Materials Yuejiao Chen, Bingang Xu, Jianliang Gong, Jianfeng Wen, Tao Hua, Chi-wai Kan, and Jiwei Deng ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b16167 • Publication Date (Web): 20 Dec 2018 Downloaded from http://pubs.acs.org on December 20, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Design of High-performance Wearable Energy and Sensor Electronics from Fiber Materials Yuejiao Chen1,2 Bingang Xu,1* Jianliang Gong,1 Jianfeng Wen,1 Tao Hua,1 Chi-Wai Kan1 and Jiwei Deng3 1Nanotechnology

Center, Institute of Textiles and Clothing, The Hong Kong Polytechnic

University, Hung Hom, Kowloon, Hong Kong 2

State Key Laboratory of Powder Metallurgy, Central South University, 410083, China

3College

of Mechanical and Electrical Engineering, Central South University, 410083, China

*Corresponding Author: [email protected] KEYWORDS: fiber materials; energy storage; energy harvesting; strain sensors; flexible electronics; nickel coating

ABSTRACT

Fiber material is composed of a group of flexible fibers that are assembled in a certain dimensionality. With its good flexibility, high porosity and large surface area, it demonstrates a great potential in development of flexible and wearable electronics. In this work, a kind of nickel/active material coated flexible fiber (NMF) electrodes, such as Ni/MnO2/rGO NMF electrodes, Ni/CNT NMF electrodes, and Ni/G NMF electrodes, are developed by a new general method. In contract with previous approaches, it is the first time to make use of porous and rich hydrophilic structures of fiber materials as the substrate to fully absorb active materials from their suspension or slurry, and then deposit a Ni layer on active material coated fiber materials. The proposed processes of active material dip-coating and then Ni electroless plating not only

ACS Paragon Plus Environment

1

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 27

greatly enhance the electrical conductivity and functional performance of fiber materials, but also can be applicable to an extensive diversity of fiber materials, like fabrics, yarns, papers, and so on, with outstanding flexibility, light-weight, high stability and conductivity for making kinds of energy and sensor devices. As demonstration, 2D Ni/MnO2/rGO NMF electrode is obtained for supercapacitor, showing excellent electrochemical performance for energy storage. Then, Ni/CNTs NMF electrodes with different dimensionalities, including 1D fiber-shaped, 2D plane and 3D spatial, are fabricated as various tensile and compressive strain sensors for observation of human’s movements and health. Finally, 2D Ni/graphene NMF electrode is developed for assembling triboelectric nanogenerator for mechanical energy harvesting. Benefiting from wearable property of the textile substrates, the obtained NMF electrodes are expected to be designed into kinds of wearable devices for the future practical applications. The NMF electrode design in this work provides a simple, stable and effective approach for designing and fabricating wearable energy and sensor electronics from fiber materials.

Introduction In the past decades, flexible or wearable electronics have inspired both scientific and commercial interests because of their remarkable application potentials in communication, medical treatment, and environmental monitoring.1-6 Valuable effort has been made towards fabrication and application of different types of wearable electronics for energy scavenging,7-8 energy storing,9-11 and strain sensing.12-14 Among which, energy harvesting is an effective technology to convert some kinds of energy from the surroundings into electrical energy.15 Triboelectric nanogenerators (TENGs) can easily convert the mechanical movement into electricity, which has caused extensive attention owing to its high energy output and high conversion efficiency, with encouraging innovations pushing forward its development.16-18


2

Page 3 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Energy storage mainly captures chemically produced energy into electricity to provide steady and continuously output. Among various emerging energy storage technologies, flexible supercapacitors (SCs) are promising candidates due to their high power density, long cycle durability, wonderful safety and good advantages of incorporating into flexible substrates.19-21 Wearable sensors, simulating a nervous system to detect signals, can be integrated into worn clothing to monitor human’s various behaviors. Strain sensors, as an important member of wearable sensors, could covert physical signals mostly originated from mechanical deformations into measurable electrical signals, which could be mechanically compliant to monitor human activities and personal health.12, 22, 23 Thus, the design and fabrication of wearable TENGs, SCs and strain sensors are highly attractive and great in demand. Fiber material is composed a group of flexible fibers that are assembled in a certain dimensionality for various applications. The typical examples of fiber materials commonly in use include 1D fiber-shaped yarn, 2D plane fabric and 3D spacer fabric.24-28 With its good flexibility, large surface area, effectively aligned pore structure, and massive hydrophilic functional groups, fiber material reveals a huge potential as flexible supporting substrate for wearable electrodes and plays a vital part in the development of flexible and wearable electronics.29-36 Its unique structural nature can easily make the fiber material have the ability of massive adsorption of water or other polar solvents. In the past few years, attempts have been made for efficient preparation of fiber materials-based electrodes for wearable electronics. A significant challenge is the conversion of the insulated substrates into conductive electrodes. Li et al. fabricated conductive substrates by direct carbonization of 2D cotton fabric into activated carbon conductive substrates for SCs’ electrodes,37 but the resultant carbonization products are fragile, and this method cannot be applied to many other types of fiber materials. Sun et al. made the


3


Page 4 of 27

stretchable 1D fiber-shaped yarn conductive by coating with polypyrrole @CNTs.38 However, the coating is not stable and easy to fall off. Xu et al. reported polypyrrole-coated 2D cotton fabric through in situ chemical polymerization,10 while the practical application of conducting polymers coated electrodes is limited by their high resistance and stability. More recently, studies were carried out for developing metals/active materials-coated 2D fiber materials.39-41 These works mainly combine metal coating and active material deposition process. Although the metal coating could help form conductive layer, the original hydrophilicity and adhesion of fiber materials would be significantly reduced, resulting in that only electrochemical deposition or hydrothermal growth method can be used to develop active materials on metal-coated electrodes. These restrict the use of rough, porous fibers network with coating rich hydroxyl groups cellulose chains. Therefore, to resolve the poor electrical conductivity and exfoliation problem, and make full use of the porous and fibrous structure nature for making high-performance wearable electronics, development of new electrode fabrication method is highly needed, which should not only be generally applicable to a broad range of wearable fiber materials (e.g. 1D fiber-shaped, 2D plane and 3D spatial) but also be versatilely used for making various kinds of high-performance energy and sensory electronics (e.g. energy storage, energy harvesting, tensile/compressive strain sensor devices). Herein a new kind of wearable nickel/active materials coated fiber materials (NMF) electrodes are developed by a proposed general method. In this method, active material is first configured into suspension or slurry (see experimental detail). We make full use of porous and rich hydrophilic structures of fiber materials as the substrate to fully absorb the active materials for functional properties by dipping in suspension ink. An electroless plating is then employed to deposit a Ni layer on active materials coated fiber materials. In contract with previous


4

Page 5 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


approaches, the proposed processes of active materials dip-coating and Ni electroless plating not only greatly enhance the electrical conductivity and functional performance of fiber materials, but also effectively resolve exfoliation problem of active materials. It provides a stable, scalable, versatile and cost-effective route to fabricate a broad range of NMF electrodes with highperformance and can also be versatilely used for making various kinds of energy and sensor devices. By utilizing the NMF electrodes, we fabricated wearable SCs, TENGs, and tensile/compressive strain sensors. The simple and versatile design process allows fiber materials possess high conductivity and good compatibility for wearable technology which is important for smart wearable electronics.

RESULTS AND DISCUSSION Ni/MnO2/rGO flexible NMF electrode for SC. Figure 1a shows the preparation and fabrication process of 2D Ni/MnO2/rGO NMF electrode from a wearable 2D fabric. In the experiment, the pristine fabric was first coated with carbon spheres and graphene oxide (CS/GO) via dipping into CS/GO mixture suspension. After sensitization by SnCl2 and activation by PdCl2, the CS/G sample was dipped into the electroless plating solution to deposit a Ni layer. During this process, Ni2+ ions were in situ reduced as metallic Ni on the sensitized/activated fibers with the reducing agent. Then, the Ni/CS/GO sample was soaked in KMnO4 solution to transform Mn7+ into MnO2 (Mn4+) by oxidation of CS.42 Finally, the hydrazine monohydrate solution was used to reduce GO and remove excess KMnO4. Eventually, the obtained 2D Ni/MnO2/rGO NMF was used as the electrode for SCs. The morphology of bare, CS/GO and 2D Ni/MnO2/rGO NMF samples were realized by the Scanning electron microscopy (SEM) measurement. As depicted in Figure 1b and c, the cellulose fiber bundles are mainly interwoven


5


Page 6 of 27

with each other to form the fundamental intersection-banding framework for the bare sample. Pore, interspace, and microfibres among fibers are visible. The fiber surface is smooth with few defects or particles attached. After dyeing with CS/GO suspension, a uniform CS/GO layer with slightly smooth surface was coated on every fiber (Figure 1d and e). After Ni electroless plating process, KMnO4 treating and GO reduction, the CS/GO cellulose fibers were coated by a Ni layer with a rough and partially broken surface and the inner CS/GO layers were transferred into MnO2/rGO incorporation nanobumps (Figure 1f and g). MnO2 is unstable in acid solution, while Ni coating must happen in this situation. Thus, MnO2 was formed after nickel coating in this experiment. Meanwhile, the cellulose fibers only coated by rGO/MnO2 without Ni deposition were shown in Figure 1h. Obviously, the surface of fibers was absolutely covered by rough layers consisted of many small bulges and wrinkles, indicating the transformation of GO/CS into rGO/MnO2. Figure 1i and j further illustrate the TEM morphology of Ni/MnO2/rGO powder peeled from NMF electrodes. It is noted that numerous nanostructure-particle clusters disperse on the film with some wrinkled surface (Figure 1i). The HRTEM image in Figure 1j shows some small-nanocrystal with the lattice distance of 0.23 nm, corresponds well to the (003) plane of birnessite-type MnO2, and a lattice spacing of 0.203 nm can be assigned to the (111) plane of nickel metal. The average interlayer spacing of 0.34 nm is corresponding to the 0.34 nm plane of graphene. Besides, no obvious interval exists between rGO and MnO2, indicating a strong contact and good incorporation at the interface. The elemental mapping of the Ni/MnO2/rGO in Figure k-k4 reveals the deposition of Ni, Mn, O and C elements. Here, the nickel coating is not very uniform mainly due to the design and manufacturing process of inner MnO2 layer which was finally formed after Ni plating. Nonetheless, if MnO2 is pre-formed on fibers and then coated by nickel, this nonuniformity will disappear. The two applications behind are based on the


6

Page 7 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


electrodes coated active materials and then nickel plating, which won’t result in inhomogeneous deposition of nickel. Moreover, the uniform nickel coating in this application did not affect the performance as compared to many reported papers. Raman measurement was realized to characterize the structure transformations of the surface, as illustrated in Figure S1a. The characteristic bands at 308. 1829, and 1981 cm-1 are ascribed to cellulose of the raw sample. The two peaks from rGO centered around 1345 and 1564 cm-1 can be assigned to the D and G band of carbon, respective. The peaks at 581 and 716 corresponds to the stretching vibration of Mn-O in the MnO6 groups of MnO2, respectively.43 And X-ray diffraction (XRD) (Figure S1b) was carried out to further confirm the composition structure of the Ni/MnO2/rGO sample. The weak and broad peak at 24.9° can be indexed to the diffraction of graphene. The signals around at 25.6°, 35.6°, 37.8°, and 65.8° can be indexed to the birnessite-type MnO2 (JCPDS No. 42-1317), implying the successful transformation from CS to MnO2. Three obvious diffraction peaks at 44.4, 51.8, and 76.5° can be well indexed as those face-centered cubic Ni (JCPDS no. 04-0850). X-ray photoelectron spectroscopy (XPS) analysis was carried out to further study the component of the Ni/MnO2/rGO layer (Figure S2). The typical survey spectrum (Figure S2a) reveals the presence of Ni, Mn, O, and C elements, corresponding to the formation of nickel and manganese oxides. Figure S2b-e show the high resolution XPS spectrums. The peaks at 855.8 and 873.5 eV binding energy can be indexed as Ni 2p single of the Ni layer. The Mn 2p exhibits two peaks centered at 653.8 and 642.1 eV, corresponding to Mn 2p1/2 and Mn 2p3/2 singles of MnO2. The C1scan be fitted into the peak of 284.7 eV, assigned to sp2 hybridized carbon. The spectrum of O1s at 529.8 corresponds to Mn-O-Mn.


7


Page 8 of 27


8

Page 9 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 1. (a) Fabrication process of 2D Ni/MnO2/rGO NMF electrodes for SCs using a wearable fabric. SEM images with different magnification: (b, c) bare sample, (d, e) CS/GO sample, (f, g) Ni/MnO2/rGO sample. (h) SEM image of rGO/MnO2 without coating nickel. (i) TEM image, and (j) HRTEM image of Ni/rMnO2/rGO. (k-k4) EDX mapping of different Ni, Mn, O, and C elements in the Ni/rMnO2/rGO. To clarify the effect of MnO2, Ni and rGO on the electrochemical performance of Ni/MnO2/rGO NMF electrodes, Ni sample, Ni/MnO2 sample, Ni/rGO sample and MnO2/rGO sample were conducted at the same test conditions, as shown in Figure S3. First, nickel has almost no capacity contribution in Ni/MnO2/rGO composition (Figure S3a), but it can make the capacity of Ni/MnO2/rGO composition obviously increased (Figure S3d), which should be ascribed to the conductivity enhancement after nickel addition. From Figure S3b and c, both MnO2 and rGO give a capacity contribution as compared with Ni/MnO2/rGO sample and MnO2 shows more capacity in the Ni/MnO2/rGO composition. Figure S4 also give the schematic resistances of Ni/MnO2/rGO sample, MnO2/rGO sample and MnO2 sample, showing that the nickel, like a current collector, is the mainly conductive material. While, rGO serve as networks intercalated by MnO2 particles to enhance the conductivity of MnO2. The electrochemical test of 2D Ni/MnO2/rGO NMF electrode was carried out in a three-electrode cell, displayed in Figure S5. Based on the good test performance, solid-state flexible symmetric SCs are fabricated with NMF electrodes (Figure 2a). The detailed CV curves at an operating voltage between 0 and 1 V in Figure 2b exhibit an approximate rectangular shape at different san rates, reflecting typical capacitive behavior of the active material. And the rectangle shape of cyclic voltammograms are not quasi-rectangular, revealing a nonideal electrical double-layer capacitance behavior, which can be attributed to the poor ionic conductivity of polymer electrolytes when compared to liquid electrolyte that can marginally weak the CV shape. Figure 2c displays the values of areal capacitances calculated according to their corresponding CV curves. the SC acquire its


9


Page 10 of 27

corresponding areal capacitances of about 412, 375, 347, 315 and 287 mF cm-2 at the scan rate of 5, 10, 20, 50 and 100 mV/s, respectively. Figure 2d displayed nearly symmetric galvanostatic charge-discharge (GCD) curves at various current densities with very small voltage drops, indicating good SC behaviors. The charge storage of electrode material is originated from the weak adsorption of surface cations (Li+, K+, Na+) and redox reaction between them, according to the reaction: MnO2 + Li+ + e- ←→ MnOOLi,44 which almost won’t affect the volume change of MnO2 and then affect the outer nickel layer intact. As summarized in Figure 2e, the estimated capacitance values are about 468, 434, 390, 333, 303, and 280 mF/cm2 at current densities of 0.8, 1, 1.5, 2, 3 and 4 mA/cm2, respectively, and their corresponding volumetric capacitance values are 9.4, 8.7, 7.8, 6.6, 6.1 and 5.6 F/cm3. The approving results can be ascribed to the good conductivity, the porous structure of the fiber materials, and the good intercalation between rGO networks and MnO2. The corresponding profile of power density versus energy density is shown in Figure 2f. It exhibits an outstanding energy density of 65 µW h/cm2 (1.3 mW h/cm3) at a power density of 0.4 mW/cm2 (8 mW/cm3), and this remains 38 µW h/cm2 (0.77 mW h/cm3) at a power density of 2 mW/cm2 (40 mW/cm3), confirming its high performance. From Figure 2f, the values are generally better than those recently reported 2D flexible SC devices with other types.45-51 Such as Calligraphic ink coated conductive textile (43 µW h/cm3),45 Breathable PPy coated air-laid paper (62.4 µW h/cm2),46 Transparent carbon film (47 µW h/cm3),47 Carbon coated textile (9.8 µW h/cm2),48 Ni(OH)2/NGP//Mn3O4/NGP paper (0.35 mW h/cm3),49 Cu2O/Cu/GCP paper (10.8µW h/cm2),50 RGO/MnO2//RGO paper (35.1 µW h/cm2).51 Cyclic test exhibits wonderful stability with capacitance retention of 89.6% after a very long CV cycle number of 3000 cycles at scan rate of 50 mV/s (Figure 2g). The left in Figure 2h reveals the GCD curves of single SC and two-in-series SC. After in series connection, the output voltage of


10

Page 11 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


the SC can extend to 2 V. And two-in-series SC shows nearly the same discharge time with the single SC. After being fully charged, the flexible device made of two SCs in series could successfully power commercial yellow light emitting diode (LED) (right in Figure 2h). Flexibility test of the SC device was conducted at 30 mV/s under different deformation states, such as flat state without any distortion, bent state in a certain angle, twisted state by twisting and stretched state by stretching (Figure 2i). The measured CV curves displayed a similar shape almost without any distortion under different deformation, even at the twisted and stretched states, indicating the good electrochemical durability and flexibility of the device. Based on above discussion, the excellent performance of the as-prepared 2D Ni/MnO2/rGO NMF electrodes may benefit from the following facts: the porous and rich hydrophilic structure of fiber material allow itself to fully absorb CS/GO suspension into the fibers and be converted to MnO2/rGO, which is used as active materials for preparing 2D electrode with enough flexibility to be frequently bent, twisted, or randomly cut into kinds of shapes; a certain amount rGO networks intercalated by MnO2 particles could enhance the conductivity of MnO2; the rough surface of MnO2/rGO layer can easily allow Ni2+ ions firmly be absorbed on the surface and reduced to metal Ni, greatly enhancing the conductivity of the substrate and protecting active materials from exfoliation; the distinct cross-linked framework formed by multiple individual fibers stacked and intertwined with each other improved the utilization rates of electrode materials due to the enhancement of surface area. Overall, the natural hygroscopic property of the 2D fiber materials and good formation of Ni/MnO2/rGO NMF electrode can provide accessible diffusion channels to improve the charge transfer. In view of the excellent electrochemical properties, the obtained Ni/MnO2/rGO NMF electrode could be used as a promising electrode for high-performance wearable energy storage electronics.


11


Page 12 of 27

Figure 2. (a) Schematic illustration for 2D Ni/MnO2/rGO NMF SC. (b) CV curves obtained at different scan rates. (c) The specific capacity values calculated from CV curves. (d) Galvanostatic charge-discharge (GCD) curves at different current densities. (e) The specific capacitance values calculated from GCD curves. (f) Ragone plot of the solid-state SC. (g) Cyclic stability performance at 50 mV/s. The inset is the CV curves before and after 3000 times cycles. (h) GCD curves of a single SC and two-in-series SC (left); a yellow LED indicator lighted by two NMF SCs in series (right). (j) CV curves of the SC under different mutative conditions.

Ni/CNT flexible NMF electrodes for strain sensors. To fabricate a highperformance wearable strain-sensitive electronic, a 2D NMF electrode was designed to make a strain sensor. A stretchable fabric was soaked into carbon nanotube (CNT) ink fully and then treated by Ni electroless plating to obtain a 2D Ni/CNT NMF for the fabrication of tensile strain sensor. Such method can also be applicable to flexible substrates in other dimensionalities, such


12

Page 13 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


as 1D stretchable fiber-shaped yarn and 3D compressive spacer fabric, for various tensile and compressive sensors (see Figure S6). The obtained Ni/CNT NMF electrode is highly stretchable owing to its elasticity nature (Figure 3c, d). The SEM image of a pure sample consisting of multiple bundles of microfiber tightly interweaved and stacked to form the basic framework displayed a smooth surface without any impurity (Figure 3a). With the CNT and Ni coating, the pristine morphology was maintained, and crater-like layer fixed on the surface of fibers was distinctly observed (Figure 3b). The configuration of the wearable strain sensor is displayed schematically in Figure 3e. Briefly, the sensor is constructed by using two conductive copper electrodes integrated on the end of the Ni/CNT coated stretchable fabric with silver wire. The operational principle for the strain sensor can be related to the elastic substrate and the coated conductive layer. The elastic substrate endows the sensors stretchable and repeatable while the outer conductive layer coated around the elastic core makes the sensor conductive and provides resistance change when the fabric is stretched. When the sensor is extended, the contact resistance between the joint of Ni/MnO2 increases, resulting in the corresponding increase of the whole sensor resistance; the sensor resistance can decrease gradually to the initial level during the relaxing process of the sensor. Therefore, the sensor can transmit the corresponding signal according to the sensor resistance or current change under different applied strain. Here, the relative resistance variations (defined as △R/Ro, where △R = R – Ro, R is the real time resistance of the sensor and Ro is the original resistance before deformation) can be monitored upon different stretching states. And the slope of resistance variation vs strain can be evaluated to be sensitivity, called the gauge factor (GF, GF = (△R/Ro)/ε, ε is an applied strain). As depicted in Figure 3f, the (R-Ro)/Ro values of the sensor increase with the strain ranging from 0 to 30%. Before stretching, the


13


Page 14 of 27

samples had an initial resistance (Ro) of 45 Ω; after stretching, the real-time resistance (R) increased from 45 to 458 Ω as the applied strain increased from 0 to 30%. The resistance change linearly increased when the applied strain is under 25% with a GF of 36.8, displaying a higher sensitivity as compared with some other reported 2D strain sensors.52-56 And then it stayed almost unchanged in range of 25-30%. Such electromechanical appearance is closely related to the original structure of fiber materials, the mechanical nature of the elastic substrate, and the fabrication of sensor electrodes. After releasing, the resistance of the sensor decreased with some hysteresis, which can be attributed to the elastic property of the selected fabric and a degradation in elasticity of the fabric caused by the strain. Thus, the sensor exhibits stable and credible response to the applied tensile strain of 0-25%. Figure 3g exhibits successive responses of the strain sensor on the multicycle procedure upon various strains. It is clear that the patterns of each responsive cycle are almost identical, indicating a good responsiveness to the cyclic strain applied. The mechanical repeatability of the sensor is investigated with 500 cyclic stretchingreleasing tests at 15%, as shown in Figure 3h. The amplitude increases in the first 100 cycles and then stabilizes afterwards, exhibiting good stability and reproducibility. No significant hysteresis was found according to the relationships of relative resistance changes versus strain (inset in Figure 3h), confirming good mechanical durability and stability. A comparison of the Ni/CNT NMF electrodes sensor and other reported sensors is shown in Table S1, displaying higher or comparable performance of the Ni/CNT NMF electrode, indicating an effective design for flexible stretchable strain sensors.


14

Page 15 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3. (a, b) SEM images of the pristine sample before and after treatment. (c, d) Stretchability of the Ni/CNT NMF electrode. (e) Schematic diagram of the 2D Ni/CNT NMF strain sensor. (f) resistance-strain curve under a 30% strain by stretching and releasing treating. (g) Real-time resistance changes under various cyclic strains. (h) The stability of the sensor at a strain of 15% for 500 cycles. Inset is the enlarged 9 cycles of the figure. (i) Resistance signal of the sensor in monitoring wrist joint bending at different angles. (j) Resistance signal of the sensor in monitoring finger bending. (k) A fabricated sensor adhered to the knee, (l) the corresponding signals under motions. (m) Responsive curves when speaking. The inset is the sensor attached to throat of a person.


15


Page 16 of 27

To examine the potential function of Ni/CNT flexible NMF device as wearable sensors for human movement, the sensor is used to simultaneously detect subtle and intensive human motions in real-time. As displayed in Figure 3i, the response signal of resistance changes under wrist bending at different angles was measured. When the wrist joint was bent at varying angles, the response signal increased with the wrist flexed at an angle and then returned to initial level. Therefore, the bending motion of a wrist can be easily detected by recording resistance changes of the sensor. Meanwhile, the movement speed and range can be monitored by rate and amplitude of resistance curves. When the sensor was fixed onto the knuckle (Figure 3j), finger bending shows fast responses under different bending states with good stability. With the increase of bending angle, the resistance change increases correspondingly to form a step signal. Besides, a small overshoot appears at the curve when fingers bent suddenly, which can be ascribed to the viscoelastic nature of the fabrics.57,58 When the sensor is fixed onto a knee by medical adhesive tape (Figure 3k), different knee-related limb movements can be easily recorded and discriminated, such as flexing/extending, walking, jogging, and jumping, displaying distinctive response curves (Figure 3l). To capture tiny physiological signal, we attached the wearable sensor to the throat to monitor skin vibration and recognize sounding during speaking (Figure 3m). Notable characteristic signal curves can be monitored with good repeatability when the throat emitted different words, such as “Hello”, “Bye”, “Like” and “PolyU”, endowing the sensor potential applications in phonation rehabilitation exercise and human-machine interactions. The method to prepare 2D NMF electrodes can also be applicable to flexible fiber-material substrates in other dimensionalities, such as 1D fiber-shaped yarn and 3D spacer fabric. After being treated, the 1D stretchable and 3D compressive fiber materials were uniformly coated with Ni/CNT (Figure S6). Their corresponding performances are


16

Page 17 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


measured, as shown Figure S7 and 8, respectively, performing good electromechanical properties as smart and wearable sensors. Through those extensive investigation mentioned in the supporting information, we conclude that, any kind of absorbent fibers material can be coated with Ni/CNT by the “dipping-electroless plating” method, making those compressible or stretchable substrates keep remarkable conductivity and display good electromechanical property as wearable smart textiles with electrical functionalities.

Ni/G flexible NMF electrode for TENG. To fabricate a wearable energy harvesting device, a 2D NMF electrode was designed and assembled to a TENG. A highly conductive NMF was obtained through full soaking adsorption in graphene (G) ink and electroless deposition of Ni coating, which was then utilized as current collector and electrode for TENG. Figure 4a gives the optical photograph of the sample coated with G and Ni layer. The SEM image with low magnification displays a typically fibre braiding structure with an elastic state of the Ni/G NMF (Figure 4b). The SEM image with higher magnification in Figure 4c displays clearly visible fibrous microstructure with a more evident interconnected homogeneous sheath on the fiber. The Ni/G coating with nanoscaled roughness can be benefit for enhancing of the output power by improving surface charge density of TENG. And the coating reserved the woven structure of the pristine textile and interstitials among the fibers, not making the TENG based fiber materials lose its original porous cross-linked network structure. To prepare the flexible TENG for harvesting mechanical energy, the obtained Ni/G NMF served as bottom contact layer, a polydimethylsiloxane (PDMS) film accompanied with Al foil served as the top contact layer, and polypropylene (PP) served as the nonconductive substrate material, as illustrated in Figure 4d. Based on the metal-insulator triboelectric pairs, the TENG device could be divided into two parts. One is the PDMS film acting as a triboelectric dielectric


17


Page 18 of 27

layer which is easy to attract electrons, covered with conductive Al layer on its outer surface to serve as an induced charge collector and an electrode for connecting to the external circuit. Another is Ni/G coated fabric also used as a triboelectric active material, as well as the electrode. The rough nanostructure on the surface of each fiber after Ni/G coating and the obvious crosslinking framework between multiple intertwined fibers could increase the effective contact area and friction between the fabric and PDMS during contact and separation, promoting the triboelectric occurrence. Contact and separation occurred between the surfaces of the Ni/G NMF and the silicon rubber. The generated output voltages generated from the TENGs across a resistance load of 8 MΩ were monitored, displaying an alternating electric signal with an identical frequency of applied force (Figure 4e). An output voltage of approximately 23 V by applying an external compressive force of 1000 N (equivalent to 278 KPa) was observed. Obviously, almost identical peak values of positive and negative voltage generated by the TENGs were observed, showing continuous sinusoidal cycles. Each stage of the cycle involved a contact and separation behavior, leading to an approximate symmetry curve with a pair of positive peak and negative peak (Figure 4f). This process of electricity generation cycle was accompanied with the working mechanism based on the coupling effects of triboelectrification and electrostatic induction, as displayed in Figure S9. Initially, there is no contact between the Ni/CNT fabric and PDMS film, resulting in no output signal is observed. As the two layers contact with each other by a compressive force, the surface of the fabric electrode and dielectric object produce a pair of friction pair. Due to the ability differences in attracting electron between the two surfaces, PDMS on the top of the triboelectric series is negatively charged during contact electrification. While Ni/CNT material on the bottom of the triboelectric series is easily positively charged during


18

Page 19 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


contact electrification. That is, electrons are injected from Ni/CNT to PDMS and leave positive charges on the Ni/CNT fabric, generating an insignificant electrostatic potential. Subsequently, when the force is released, the charges are transferred through the external load with a current generated. The electron flowing will last until a new electrostatic equilibrium state is constructed. When a force is applied again, it drives the charges flow back the bottom through the external circuit that generated a reverse current. The current disappeared when the charge reaches the bottom position. Therefore, alternating current signal with a whole cycle will be generated with continuous press and release of an external load. The cycle is continuously repeated, and current is generated. As the applied impact force increased from 50 to 800 N, the output voltage located in peak position increased, as shown in Figure 4g. This increasing trend can be obviously observed by the relationship values between the voltage and current density on the applied forces shown in Figure 4h. We further investigated the cycle stability of the output voltages upon continuous application of compressive force to the TENG. The TENG was continuously treated for about 1500 cycles at a given force (1000 N), equal to the pressure from normal walking of a person, as shown in Figure 4i. No any degradation could be found after 1500 cycles with a generated output voltage of 23 V, showing the high stability of our Ni/G NMF TENG in power generation and excellent advantage as a sustainable power source for wearable harvesting devices. It confirms that our Ni/G NMF TENG can easily harvest the mechanical energy from body motion and effectively convert it into usable electricity. We also changed G into CNT to form Ni/CNT NMF electrode using the same fabrication method. The obtained electrode for TENG also displayed good electromechanical performance (Figure S10). A comparison between Ni/CNT NMF electrode TENG and other reported TENGs is shown in


19


Page 20 of 27

Table S2, which shows higher or comparable performance of the Ni/CNT NMF electrode, indicating an effective design for flexible TENGs.

Figure 4. (a) Photograph of Ni/G NMF. (b, c) SEM images with different magnification of Ni/G NMF. (d) Schematic of flexible TENG based Ni/G NMF by measuring the output voltages with a 1 MΩ resistance load. (e) Typical voltage signals triggered by a PDMS film at 1000 N. (f) The magnified electric signal generated by one impact cycle. (g) The output voltages under different applied impact forces. (h) Curve of the voltage and current density under applied forces. (i) Output voltages with continuous compressive force over 1500 cycles.

CONCLUSIONS In summary, a new kind of flexible and wearable NMF electrodes with outstanding flexibility, lightweight, and high conductivity is developed by a proposed general method, which have been demonstrated their promising applications in wearable energy storing, energy harvesting and strain sensing. Unlike the previous approaches, mainly depositing metal first and then coating


20

Page 21 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


active material, greatly restricts the use of original hydrophilicity and adhesion of fiber materials, resulting only electrochemical deposition or hydrothermal growth could be used to develop active materials on metal-coated electrodes. The method in this work we proposed is able to make the fiber materials of different dimensionalities highly conductivity, promote the active materials stable on the surface, and make use of the unique structures of fiber materials for fully adsorption of active materials. Once the flexible fibers are fully coated with kinds of Ni/active materials, it could be designed into various wearable energy and sensor devices. And three applications are realized by nickel/active materials electrodes prepared by the same method, displaying excellent performance in energy and sensor devices. It provides a simple and effective approach to design and fabricate flexible and wearable energy and sensor devices from fiber materials.

METHODS Materials. All other chemicals were purchased from Sinopharm Chemical Reagent Co., Ltd without further purification. The fabric was obtained from a waste lab coat. Elastic yarn and 3D spacer were purchased from a usual market in HK. Ni/MnO2/rGO flexible NMF electrode for SC. GO suspension with 4.5 mg/mL was prepared by the modified Hummers method. For CS suspension, a solution of 4g glucose and 40 mL of distilled water was carbonized a 50 mL Teflon for 6 h at 160 oC to obtain 0.1 g/mL CS suspension.42 4 mL GO suspension and 9 mL CS suspension were mixed and sonicated to obtain CS/GO ink. A pristine fabric was soaked in the CS/GO ink for 1 min and then dried at 60 oC to prepare CS/GO sample. For electroless plating process, the above sample was sensitized by a solution (0.01 g/mL SnCl2, 40 mL/L 38% HCl), and then activated with a solution (0.5 µg/mL PdCl2, 20 mL/L 38% HCl) at room temperature for 15 min, respectively. After that, it was dipped into a mixed solution with 0.05 M NiSO4·6H2O, 0.1 M C6H8O7·H2O, 0.2 M NaH2PO2·H2O, and 4 mL NH3·H2O for 10 min at 80 oC, resulting in the Ni layer on CS/GO sample. The obtained Ni/CS/GO sample was immersed into 0.05 M KMnO4 to get Ni/MnO2/GO sample. After rinsing in DI water, it was reduced by 10 uL/L hydrazine-hydrate (98%) at 90 oC for 1 h to obtain Ni/MnO2/rGO NMF electrode. To clarify the effect of MnO2, Ni and rGO on electrochemical properties of Ni/MnO2/rGO NMF electrodes, Ni/rGO sample, Ni/MnO2 sample and MnO2/rGO sample were respectively obtained by the same process. Finally, two as-fabricated Ni/MnO2/rGO NMF electrodes were coated with PVA/LiCl (6.3 g LiCl, 3 g PVA powder, 30 mL H2O) as gel electrolyte and separator, and left in air for 12 h solidify the electrolyte.


21


Page 22 of 27

Ni/CNT flexible NMF electrode for strain sensor. 90 mg of CNT with average diameter of 50 nm (XF nano, Nanjing) was mixed with carboxyl methyl cellulose (CMC) in a weight ratio of 90:10 with 15 mL H2O water as a dispersant via magnetic stirring for 1 h. Then, the mixture was treated by ultrasonication for 8 h to obtain dilute CNT slurry. A stretchable 2D wearable fabric was soaked in this slurry for 30s and then dried. These were repeated three times to realize full adsorption. Then, the above sample was sensitized by a solution (0.01 g/mL SnCl2, 40 mL/L 38% HCl), and activated by a solution (0.5 µg/mL PdCl2, 20 mL/L 38% HCl) for 15 min, respectively. And then, it was dipped into a mixture solution with 0.05 M NiSO4·6H2O, 0.1 M C6H8O7·H2O, 0.2 M NaH2PO2·H2O, 4 mL NH3·H2O) for 10 min at 80 oC, resulting in the Ni layer on CNT sample. The Ni electroless deposition method can be performed under ambient conditions at a large scale without any expensive equipment. Two copper wires as conductive line were fixed on the 2D stretchable Ni/CNT NMF (2 cm x 1 cm) as electrodes by silver pastes. The 1D stretchable fiber-shaped yarn and 3D spacer fabric were treated in the same process as the above 2D NMF electrode.

Ni/G flexible NMF electrode for TENG. 90 mg of graphene (XF nano, Nanjing) was mixed with carboxyl methyl cellulose (CMC) in a weight ratio of 90:10 with 15 mL H2O water as a dispersant via magnetic stirring for 1 h. Then the mixture underwent an ultrasonication treatment for 8 h to obtain dilute graphene slurry. A wearable fabric (2 cm x 1.5 cm) was soaked in this slurry for 30s and then dried. These were repeated three times to realize full adsorption. Then, the obtained sample was sensitized and activated by the above process, resulting in the Ni layer on G NMF. The PDMS (XE15-645, Momentive) was obtained by mixing two components in a 1: 1 weight ratio and casting on to the acrylic sheet with a thickness of 1.5 mm. Then, the obtained PDMS film was connected to a copper tape as an electrode. The Ni/G NMF electrode and PDMS film connected with a copper tape were assembled for the TENG device.

Material and electrochemical characterization. The morphology, structure, and composition of electrode materials were characterized by Scanning electron microscopy (SEM, Tescan VEGA3), X-ray diffraction (XRD, Rigaku SmartLab), Raman spectroscope (JY-HR800, the excitation wavelength is 532 nm), transmission electron microscope (TEM, JEOL JEM 2100), and X-ray photoelectron spectroscopy (XPS, ESCALAB 250). The electrochemical tests were performed in 1 M Na2SO4 aqueous electrolyte in a threeelectrode system with Versa STAT3 electrochemical workstation at room temperature. A Ni/MnO2/rGO NMF electrode served as a working electrode, an Ag/AgCl electrode served as reference electrode and a a Pt foil served as a counter electrode. Electrochemical impedance spectra (EIS) were carried out at frequencies ranging from 0.01 to 100 000 Hz with a potential amplitude of 5 mV. The sensing-fabric, sensing-yarn and sensing-3D fabric samples were tested at a gauge of 20 mm long, 100 mm/min of extension speed, and 0.2 cN of extension. Electromechanical performance of the sensor was examined using the Instron 5944 Micro Tester and the Keithley Model 2010 Multimeter was used to vary the loading force at different cyclic extensions. The Keyboard Life Tester (ZX-A03) was used to evaluate the output voltage or current of TENG and provide a


22

Page 23 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


continuous sinusoidal curve with the displacement from 0 to +10 mm and frequency from 1 to 5 Hz. The DAQ (Dewetron, Dewe-2600 DAQ system) was used to monitor the force signal, and Keisight DSO-X3014A oscilloscope was used to collect the voltage signal.

ASSOCIATED CONTENT Supporting Information Raman spectra and XRD patterns; XPS spectra; CV curve comparisons; Digital images of sensor; Electromechanical performance of 1D Ni/CNT stretchable fiber-shaped sensor; Tables for comparison; Electromechanical performance of the 3D Ni/CNT sensor; Electricity generation mechanism of the TEN; SEM image and performance of Ni/CNT sample for TENG.

ACKNOWLEDGMENT The authors would like to acknowledge the funding support from the Hong Kong Polytechnic University (Project No. 1-YW1B, G-YBV2) for the work reported here.

REFERENCES 1. Yamada, T.; Hayamizu, Y.; Yamamoto, Y.; Yomogida, Y.; Izadi-Najafabadi, A.; Futaba, D. N.; Hata, K. A stretchable carbon nanotube strain sensor for human-motion detection. Nat. Nanotechnol. 2011, 6, 296-301. 2. Kim, K. S.; Zhao, Y.; Jang, H.; Lee, S. Y.; Kim, J. M.; Kim, K. S.; Ahn, J. H.; Kim, P.; Choi, J. Y.; Hong, B. H. Large-scale pattern growth of graphene films for stretchable transparent electrodes. Nature 2009, 457, 706-710. 3. Weng, W.; Chen, P. N.; He, S. S.; Sun, X. M.; Peng, H. S. Smart Electronic Textiles. Angew. Chem. Int. Edit. 2016, 55, 6140-6169. 4. Zhai, S. L.; Karahan, H. E.; Wei, L.; Qian, Q. H.; Harris, A. T.; Minett, A. I.; Ramakrishna, S.; Ng, A. K.; Chen, Y. Textile energy storage: Structural design concepts, material selection and future perspectives. Energy Storage Mater. 2016, 3, 123-139. 5. Amjadi, M.; Kyung, K. U.; Park, I.; Sitti, M. Stretchable, Skin-Mountable, and Wearable Strain Sensors and Their Potential Applications: A Review. Adv. Funct. Mater. 2016, 26, 16781698. 6. Kostarelos, K.; Novoselov, K. S. Graphene devices for life. Nat. Nanotechnol. 2014, 9, 744-745. 7. Pu, X.; Song, W. X.; Liu, M. M.; Sun, C. W.; Du, C. H.; Jiang, C. Y.; Huang, X.; Zou, D. C.; Hu, W. G.; Wang, Z. L. Wearable Power-Textiles by Integrating Fabric Triboelectric


23


Page 24 of 27

Nanogenerators and Fiber-Shaped Dye-Sensitized Solar Cells. Adv. Energy Mater. 2016, 6, 1601048. 8. Zhao, Z. Z.; Yan, C.; Liu, Z. X.; Fu, X. L.; Peng, L. M.; Hu, Y. F.; Zheng, Z. J. MachineWashable Textile Triboelectric Nanogenerators for Effective Human Respiratory Monitoring through Loom Weaving of Metallic Yarns. Adv. Mater. 2016, 28, 10267-10274. 9. Yang, Y.; Huang, Q. Y.; Niu, L. Y.; Wang, D. R.; Yan, C.; She, Y. Y.; Zheng, Z. J. Waterproof, Ultrahigh Areal-Capacitance, Wearable Supercapacitor Fabrics. Adv. Mater. 2017, 29, 1606679. 10. Chen, Y. J.; Xu, B. G.; Wen, J. F.; Gong, J. L.; Hua, T.; Kan, C-W; Deng, J. W. Design of Novel Wearable, Stretchable, and Waterproof Cable-Type Supercapacitors Based on HighPerformance Nickel Cobalt Sulfide-Coated Etching-Annealed Yarn Electrodes. Small 2018, 14, 1704373. 11. Dong, L. B.; Xu, C. J.; Li, Y.; Wu, C. L.; Jiang, B. Z.; Yang, Q.; Zhou, E. L.; Kang, F. Y.; Yang, Q. H. Simultaneous Production of High-Performance Flexible Textile Electrodes and Fiber Electrodes for Wearable Energy Storage. Adv. Mater. 2016, 28, 1675-1681. 12. Wang, Y.; Wang, L.; Yang, T. T.; Li, X.; Zang, X. B.; Zhu, M.; Wang, K. L.; Wu, D. H.; Zhu, H. W. Wearable and Highly Sensitive Graphene Strain Sensors for Human Motion Monitoring. Adv. Funct. Mater. 2014, 24, 4666-4670. 13. Cheng, Y.; Wang, R. R.; Sun, J.; Gao, L. A Stretchable and Highly Sensitive GrapheneBased Fiber for Sensing Tensile Strain, Bending, and Torsion. Adv. Mater. 2015, 27, 7365-7371. 14. Zhang, M. C.; Wang, C. Y.; Wang, H. M.; Jian, M. Q.; Hao, X. Y.; Zhang, Y. Y. Carbonized Cotton Fabric for High-Performance Wearable Strain Sensors. Adv. Funct. Mater. 2017, 27, 1604795. 15. Wang, Z. L.; Song, J. H. Piezoelectric nanogenerators based on zinc oxide nanowire arrays. Science 2006, 312, 242-246. 16. Bai, P.; Zhu, G.; Liu, Y.; Chen, J.; Jing, Q. S.; Yang, W. Q.; Ma, J. S.; Zhang, G.; Wang, Z. L. Cylindrical Rotating Triboelectric Nanogenerator. ACS Nano 2013, 7, 6361-6366. 17. Li, S. M.; Wang, S. H.; Zi, Y. L.; Wen, Z.; Lin, L.; Zhang, G.; Wang, Z. L. Largely Improving the Robustness and Lifetime of Triboelectric Nanogenerators through Automatic Transition between Contact and Noncontact Working States. ACS Nano 2015, 9, 7479-7487. 18. Li, Z. L.; Shen, J. L.; Abdalla, I.; Yu, J. Y.; Ding, B. Nanofibrous membrane constructed wearable triboelectric nanogenerator for high performance biomechanical energy harvesting. Nano Energy 2017, 36, 341-348. 19. Zang, X. B.; Chen, Q.; Li, P. X.; He, Y. J.; Li, X.; Zhu, M.; Li, X. M.; Wang, K. L.; Zhong, M. L.; Wu, D. H.; Zhu, H. W. Highly Flexible and Adaptable, All-Solid-State Supercapacitors Based on Graphene Woven-Fabric Film Electrodes. Small 2014, 10, 2583-2588. 20. Scalable fabrication of high-power graphene micro-supercapacitors for flexible and onchip energy storage. Nat. Commun. 2013, 4, 2446. 21. Chen, L. F.; Yu, Z. Y.; Ma, X.; Li, Z. Y.; Yu, S. H. In situ hydrothermal growth of ferric oxides on carbon cloth for low-cost and scalable high-energy-density supercapacitors. Nano Energy 2014, 9, 345-354. 22. Wang, C. Y.; Li, X.; Gao, E. L.; Jian, M. Q.; Xia, K. L.; Wang, Q.; Xu, Z. P.; Ren, T. L.; Zhang, Y. Y. Carbonized Silk Fabric for Ultrastretchable, Highly Sensitive, and Wearable Strain Sensors. Adv. Mater. 2016, 28, 6640-6648. 23. Park, J.; You, I.; Shin, S.; Jeong, U. Material Approaches to Stretchable Strain Sensors. ChemPhysChem 2015, 16, 1155-1163.


24

Page 25 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


24. Guo, Y.; Tao, X.; Xu, B.; Feng, J.;Wang, S. Structural characteristics of low torque and ring spun yarns. TEXT. RES. J. 2011, 81, 778-790. 25. Liu, H.; Tao, X.M.; Choi, K.F.; Xu, B. Analysis of the relaxation modulus of spun yarns. TEXT. RES. J. 2010, 80, 403-410. 26. Tang, H.B.; Xu, B.; Tao, X.M. A New analytical solution of the twist wave propagation equation with its application in a modified ring spinning system. TEXT. RES. J. 2010, 80, 636641. 27. Xu, B.; Qu, L. A new practical modal method for rotor balancing. P I MECH ENG C-J MEC 2001, 215, 179-190. 28. Xu, B.; Tao X. Integrated approach to dynamic analysis of yarn twist distribution in rotor spinning. TEXT. RES. J. 2003, 73,79-89 29. Li, X.; Hua, T.; Xu, B. Electromechanical properties of a yarn strain sensor with graphene-sheath/polyurethane-core, Carbon 2017, 118, 686-698. 30. Chen, L. F.; Yu, Z. Y.; Wang, J. J.; Li, Q. X.; Tan, Z. Q.; Zhu, Y. W.; Yu, S. H. Metallike fluorine-doped β-FeOOH nanorods grown on carbon cloth for scalable high-performance supercapacitors. Nano Energy 2015, 11, 119-128. 31. Yu, Q. Y.; Xia, X. F.; Ye, H. T.; Wang, L.; Jiao, X. Y.; Wu, L.; Hao, Q. L. ThreeDimensional Hierarchical Structure ZnO@C@NiO on Carbon Cloth for Asymmetric Supercapacitor with Enhanced Cycle Stability. ACS Appl. Mater. Interfaces 2018, 10, 3549-3561. 32. Kaushik, V.; Lee, J.; Hong, J.; Lee, S.; Lee, S.; Seo, J.; Mahata, C.; Lee, T. Textile-Based Electronic Components for Energy Applications: Principles, Problems, and Perspective. Nanomaterials 2015, 5, 1493-1531. 33. Zhang, Q. C.; Sun, J.; Pan, Z. H.; Zhang, J.; Zhao, J. X.; Wang, X. N.; Zhang, C. X.; Yao, Y. G.; Lu, W. B.; Li, Q. W.; Zhang, Y. G.; Zhang, Z. X. Stretchable fiber-shaped asymmetric supercapacitors with ultrahigh energy density. Nano Energy 2017, 39, 219-228. 34. Zhang, Q. C.; Wang, X. N.; Pan, Z. H.; Sun, J.; Zhao, J. X.; Zhang, J.; Zhang, C. X.; Tang, L.; Luo, J.; Song, B.; Zhang, Z. X. X.; Lu, W. B.; Li, Q. W.; Zhang, Y. G.; Yao, Y. G. Wrapping Aligned Carbon Nanotube Composite Sheets around Vanadium Nitride Nanowire Arrays for Asymmetric Coaxial Fiber-Shaped Supercapacitors with Ultrahigh Energy Density. Nano Lett. 2017, 17, 2719-2726. 35. Zhang, Q. C.; Xu, W. W.; Sun, J.; Pan, Z. H.; Zhao, J. X.; Wang, X. N.; Zhang, J.; Man, P.; Guo, J. B.; Zhou, Z. Y.; He, B.; Zhang, Z. X.; Li, Q. W.; Zhang, Y. G.; Xu, L.; Yao, Y. G. Constructing Ultrahigh-Capacity Zinc-Nickel-Cobalt Oxide@Ni(OH)2 Core-Shell Nanowire Arrays, for High-Performance Coaxial Fiber-Shaped Asymmetric Supercapacitors. Nano Lett. 2017, 17 (12), 7552-7560. 36. Zhao, J. X.; Li, H. Y.; Li, C. W.; Zhang, Q. C.; Sun, J.; Wang, X. N.; Guo, J. B.; Xie, L. Y.; Xie, J. X.; He, B.; Zhou, Z. Y.; Lu, C. H.; Lu, W. B.; Zhu, G.; Yao, Y. G. MOF for templatedirected growth of well-oriented nanowire hybrid arrays on carbon nanotube fibers for wearable electronics integrated with triboelectric nanogenerators. Nano Energy 2018, 45, 420-431. 37. Bao, L. H.; Li, X. D. Towards Textile Energy Storage from Cotton T-Shirts. Adv. Mater. 2012, 24, 3246-3252. 38. Sun, J. F.; Huang, Y.; Fu, C. X.; Wang, Z. Y.; Huang, Y.; Zhu, M. S.; Zhi, C. Y.; Hu, H. High-performance stretchable yarn supercapacitor based on PPy@CNTs@urethane elastic fiber core spun yarn. Nano Energy 2016, 27, 230-237. 39. Kim, K. N.; Chun, J.; Kim, J. W.; Lee, K. Y.; Park, J. U.; Kim, S. W.; Wang, Z. L.; Baik, J. M. Highly Stretchable 2D Fabrics for Wearable Triboelectric Nanogenerator under Harsh


25


Page 26 of 27

Environments. ACS Nano 2015, 9, 6394-6400. 40. Nagaraju, G.; Sekhar, S. C.; Bharat, L. K.; Yu, J. S. Wearable Fabrics with Self-Branched Bimetallic Layered Double Hydroxide Coaxial Nanostructures for Hybrid Supercapacitors. ACS Nano 2017, 11, 10860-10874. 41. Pu, X.; Li, L. X.; Liu, M. M.; Jiang, C. Y.; Du, C. H.; Zhao, Z. F.; Hu, W. G.; Wang, Z. L. Wearable Self-Charging Power Textile Based on Flexible Yarn Supercapacitors and Fabric Nanogenerators. Adv. Mater. 2016, 28, 98-105. 42. Liu, Y.; Cai, X. Y.; Luo, B. F.; Yan, M.; Jiang, J. H.; Shi, W. D. MnO2 decorated on carbon sphere intercalated graphene film for high-performance supercapacitor electrodes. Carbon 2016, 107, 426-432. 43. Zhang, J. X.; Zhao, X.; Huang, Z. L.; Xu, T.; Zhang, Q. H. High-performance all-solidstate flexible supercapacitors based on manganese dioxide/carbon fibers. Carbon 2016, 107, 844851. 44. Chen, L. F.; Huang, Z. H.; Liang, H. W.; Guan, Q. F.; Yu, S. H. Bacterial-CelluloseDerived Carbon Nanofiber@MnO2 and Nitrogen-Doped Carbon Nanofi ber Electrode Materials: An Asymmetric Supercapacitor with High Energy and Power Density. Adv. Mater. 2013, 25, 4746-4752. 45. Van Lam, D.; Jo, K.; Kim, C. H.; Won, S.; Hwangbo, Y.; Kim, J. H.; Lee, H. J.; Lee, S. M. Calligraphic ink enabling washable conductive textile electrodes for supercapacitors. J. Mater. Chem. A 2016, 4, 4082-4088. 46. Chen, Y. X.; Cai, K. F.; Liu, C. C.; Song, H. J.; Yang, X. W. High-Performance and Breathable Polypyrrole Coated Air-Laid Paper for Flexible All-Solid-State Supercapacitors. Adv. Energy Mater. 2017, 7, 1701247. 47. Jung, H. Y.; Karimi, M. B.; Hahm, M. G.; Ajayan, P. M.; Jung, Y. J. Transparent, flexible supercapacitors from nano-engineered carbon films. Sci. Rep. 2012, 2, 773. 48. Yuksel, R.; Unalan, H. E., Textile supercapacitors-based on MnO2/SWNT/conducting polymer ternary composites. Int. J. Energ. Res. 2015, 39, 2042-2052. 49. Feng, J. X.; Ye, S. H.; Lu, X. F.; Tong, Y. X.; Li, G. R. Asymmetric Paper Supercapacitor Based on Amorphous Porous Mn3O4 Negative Electrode and Ni(OH)2 Positive Electrode: A Novel and High-Performance Flexible Electrochemical Energy Storage Device. ACS Appl. Mater. Inter. 2015, 7, 11444-11451. 50. Wan, C. C.; Jiao, Y.; Li, J. Multilayer core-shell structured composite paper electrode consisting of copper, cuprous oxide and graphite assembled on cellulose fibers for asymmetric supercapacitors. J. Power Sources 2017, 361, 122-132. 51. Sumboja, A.; Foo, C. Y.; Wang, X.; Lee, P. S. Large Areal Mass, Flexible and FreeStanding Reduced Graphene Oxide/Manganese Dioxide Paper for Asymmetric Supercapacitor Device. Adv. Mater. 2013, 25, 2809-2815. 52. Cai, G. M.; Yang, M. Y.; Xu, Z. L.; Liu, J. G.; Tang, B.; Wang, X. G. Flexible and wearable strain sensing fabrics. Chem. Eng. J. 2017, 325, 396-403. 53. Bae, S. H.; Lee, Y.; Sharma, B. K.; Lee, H. J.; Kim, J. H.; Ahn, J. H. Graphene-based transparent strain sensor. Carbon 2013, 51, 236-242. 54. Tong, L.; Wang, X. X.; He, X. X.; Nie, G. D.; Zhang, J.; Zhang, B.; Guo, W. Z.; Long, Y. Z. Electrically Conductive TPU Nanofibrous Composite with High Stretchability for Flexible Strain Sensor. Nanoscale Res. Lett. 2018, 13, 86. 55. Seyedin, S.; Razal, J. M.; Innis, P. C.; Jeiranikhameneh, A.; Beirne, S.; Wallace, G. G. Knitted Strain Sensor Textiles of Highly Conductive All-Polymeric Fibers. ACS Appl. Mater.


26

Page 27 of 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Inter. 2015, 7, 21150-21158. 56. Lee, J.; Kim, S.; Lee, J.; Yang, D.; Park, B. C.; Ryu, S.; Park, I. A stretchable strain sensor based on a metal nanoparticle thin film for human motion detection. Nanoscale 2014, 6, 11932-11939. 57. Atalay, O.; Kennon, W. R.; Husain, M. D. Textile-Based Weft Knitted Strain Sensors: Effect of Fabric Parameters on Sensor Properties. Sensors 2013, 13, 11114-11127. 58. Ambrosi, A.; Chua, C. K.; Bonanni, A.; Pumera, M. Lithium Aluminum Hydride as Reducing Agent for Chemically Reduced Graphene Oxides. Chem. Mater. 2012, 24, 2292-2298.

TOC


27

Design of High-performance Wearable Energy and Sensor Electronics

Recommend Documents