High-Performance Cable-Type Flexible Rechargeable Zn Battery

Subscriber access provided by Kaohsiung Medical University

Energy, Environmental, and Catalysis Applications

A High Performance Cable-type Flexible Rechargeable Zn Battery Based on MnO2@CNT Fiber Microelectrode Kai Wang, Xiaohua Zhang, Jianwei Han, Xiong Zhang, Xianzhong Sun, Chen Li, Wenhao Liu, Qingwen Li, and Yanwei Ma ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b07756 • Publication Date (Web): 29 Jun 2018 Downloaded from http://pubs.acs.org on July 1, 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 30 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

A High Performance Cable-type Flexible Rechargeable Zn Battery Based on MnO2@CNT Fiber Microelectrode Kai Wang a, b, Xiaohua Zhang c, Jianwei Han a, b, Xiong Zhang a, b, Xianzhong Sun a, b, Chen Li a, b, Wenhao Liu a, b, Qingwen Li c and Yanwei Ma a, b,* a

Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, P.R. China

b

University of Chinese Academy of Sciences, Beijing 100049, PR China

*E-mail: [email protected] c

Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences

398 Ruoshui Rd, Suzhou 215123, China

KEYWORDS Flexible devices; rechargeable batteries; carbon nanotube fibers; micro-scale electrodes; gel polymer electrolytes.

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 30

ABSTRACT

Nowadays, linear-shaped batteries have received increasing attentions because the unique onedimension architecture offers omni-directional flexibility. We developed a cable-type flexible rechargeable Zn micro-battery based on a micro-scale MnO2@carbon nanotube fiber-like composite cathode and Zn wire anode. The Zn-MnO2 cable micro-battery exhibits large specific capacity, good rate performance and cyclic stability. The capacity of Zn-MnO2 cable batteries are 322 mAh/g and 290 mAh/g based on MnO2 with aqueous and gel polymer electrolyte, correspongding to the specific energy of 437 Wh/kg and 360 Wh/kg, respectively. Besides, the Zn-MnO2 cable battery shows excellent flexibility, which can be folded into arbitrary shapes without sacrificing electrochemical performance. Furthermore, we studied electrochemical properties of Zn-MnO2 cable micro-batteries with different Zn salt electrolytes, such as Zn salt with small anions (ZnSO4 or ZnCl2, etc.) and Zn salt with bulky anions (Zn(CF3SO3)2, etc.). With the merits of impressive electrochemical performance and flexibility, this first flexible rechargeable Zn-MnO2 cable-like battery presents a new approach to develop high-performance power sources for portable and wearable electronics.


2

Page 3 of 30 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


Introduction To meet the ever-growing requirement of flexible devices such as wearable electronics, roll-up displays and sensor networks, it is critically urgent to develop matchable energy-storage devices with small size, light weight, and high flexibility.1-2 As a result, flexible batteries and supercapacitors have been invented, which can retain electrochemical functions under mechanical deformation.3-6 In particular, linear-shaped batteries and supercapacitors, such as fiber supercapacitors, cable lithium batteries, and wire alkaline batteries, have received increasing attentions, because the unique one-dimension architecture offers omni-directional flexibility.7-13 They can be folded into arbitrary shapes, wrapped around body parts like the neck or the wrist as well as knitted or sewn into fabrics.14-16 Among the various energy storage devices, alkaline zinc-manganese dioxide (Zn-MnO2) batteries have long dominated the primary battery market due to low cost, high safety, easy manufacturing and high energy density.17-21 However, they usually show significant capacity fading during the initial 20 cycles owe to the formation of irreversible discharged species in alkaline electrolytes, which limits the widespread application of the Zn-based primary batteries.22-24 Currently, the rechargeability of Zn-MnO2 batteries has been improved by ameliorating the electrolyte, such as using mild acidic electrolytes.25-26 Nevertheless, to develop flexible rechargeable Zn–MnO2 batteries with high capacity and cycling durability is remains an elusive challenge.18 Recently, growing attention has been paid to develop flexible fiber-shape aqueous Zn batteries. For example, Zamarayeva et al. introduced a rechargeable Zn-Ag wire battery with silver nanoparticle embedded the conductive thread, which has a specific capacity of 1.4 mAh cm −1 and a capacity retention of above 98% after 170 cycles.7 Zeng et al. reported a flexible quasi-solid-state fiber-shaped Zn-Ni battery based on Ni–NiO heterostructured


3


Page 4 of 30

nanosheet cathode and Zn wire that exhibited 237.8 μAh cm−3 at 3.7 A g−1 and superior cycling stability.8 Yu et al. demonstrated a fiber-type alkaline Zn–MnO2 battery based on carbon fiber electrodes that could deliver a capacity of 158 mA h g−1.27 However, the current Zn-MnO2 fiber batteries are mostly non-rechargeable and suffers from sharp capacity fading, resulting in resource waste and environmental pollution. To our knowledge, there is few report on rechargeable cable (or fiber, wire)-typed Zn-MnO2 battery up to date. Very recently, Zn-MnO2 fiber rechargeable batteries have been reported by Zhi group28-30, indicating the one-dimension archetectured Zn-MnO2 rechargeable battery is quite promising. Herein, we developed a cable-type flexible solid-state rechargeable Zn-MnO2 metal microbattery based on a MnO2@CNT fiber-like composite electrode. Firstly, carbon nanotube (CNT) fiber with the diameter of around 80-100 μm was prepared by directly dry spinning from CNT arrays synthesized in a floating catalytic chemical-vapor-deposition (CVD) reactor. Then, the MnO2@CNT Fiber was obtained via a feasible electrochemical deposition process in aqueous Mn(NO3)2 solution. A cable-type flexible Zn-MnO2 micro-battery with binder-free MnO2@CNT fiber cathode and Zn wire anode was assembled, as illustrated as in Figure 1. The as-fabricated cable-type Zn-MnO2 micro-battery with various electrolytes was investigated, including aqueous mild solutions or gel polymer electrolytes. The specific capacity at 0.1 A/g (0.32C) of asprepared Zn-MnO2 batteries with ZnCl2 aqueous and ZnCl2 gel polymer electrolyte are 322 mAh/g and 290 mAh/g, correspoing to specific energy of 437Wh/kg and 360 Wh/kg, respectively. Furthermore, we studied the electrochemical properties of MnO2 cathode in different Zn salt electrolytes. The electrochemical behavior of MnO2 cathode is affected by the the molecular size of Zn salts of the electrolytes according to differential capacity analysis and cyclic voltammetry measurements. Besides, the Zn-MnO2 cable battery shows excellent


4

Page 5 of 30 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


flexibility, which can be folded into arbitrary shapes without sacrificing electrochemical performance. Experimental Section Preparation of MnO2@CNT fiber electrode The CNT arrays were synthesized by a floating catalytic chemical-vapor-deposition (FCCVD) reaction method, which were then continuously collected (wound) onto a rotating mandrel to form twisted CNT fiber by a dry-spinning process. The MnO2 nanosheets were deposited on the surface of CNT fibers via a electrochemical deposition process in 0.1 mol/L aqueous Mn(NO3)2 solution. Typically, a CNT fiber with the length of 12 cm was directly immersed into solution as work electrode. Pt plate and saturated calomel electrode (SCE) were count electrode and reference electrode, respectively. The immersion length of the CNT fiber in the reaction solution was 8cm. MnO2 nanosheets were deposited by chronoamperometry method at 1.0 V for a proper time. After MnO2 deposition, the diameter of CNT fiber becomes thicker to form MnO2@CNT fiber composite electrode. The deposition time was 15, 30 and 60min responding to MnO2-15, MnO2-30 and MnO2-60 cathode, respectively. The loading weight of MnO2 nanosheets on the CNT fiber was obtained by the weight difference before and after MnO2 deposition. Materials characterization Scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) analysis were conducted from a field-emission scanning electron microscopy (FESEM, SIGMA, ZEISS). Transmission electron microscopy (TEM) was operated on a JEOL 2100 instrument with an energy diffraction system. X-ray diffraction (XRD) patterns were collected from an X-ray


5


Page 6 of 30

diffractometer (D8 Advance, Bruker) with Cu Ka radiation. Raman spectroscopies were obtained using Renishaw inVia system with excitation wavelength of 532 nm. X-ray photoelectron spectroscopy (XPS) analysis was conducted from a PHI Quantear SXM. Assembly and electrochemical measurement of Zn-MnO2 cable batteries The as-prepared MnO2@CNT fiber with a length of 12cm was directly used as cathode without extra binder. A filter paper was cut to belt-shape (0.2cm×10cm) as separator, which pre-soaked electrolyte, placing in-between the MnO2@CNT fiber and Zn wire to avoid the contacting of cathode and anode. The overlap length of MnO2@CNT fiber and Zn wire is 8cm. The electrolytes in this work include aqueous electrolyte and gel polymer electrolyte. The fiber cathode, filter paper soaked with electrolyte and Zn wire were laminated together in sequence and further placed in a heat-shrinkable plastic tube, which was then sealed in the tube by heating to form a cable-type Zn-MnO2 battery. Zn-MnO2 cable batteries were connected onto electrochemical workstation (Biologic VMP3) to conduct cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) analysis and galvanostatic charge-discharge (GCD) measurements at room temperature. Aqueous ZnCl2 electrolyte used in this work includes 2M ZnCl2 (PH: 4.7), 2M ZnCl2-0.2M MnCl2 and 2M ZnCl2-0.4M MnCl2 aqueous solution, respectively. ZnCl2 gel polymer (1.5 M LiCl-2M ZnCl2-PVA) electrolyte was synthesized by the following steps: Typically, 0.84g LiCl, 2.73g ZnCl2 and 1g PVA was added to 10 ml deionized water with vigorous stirring, which was then steadily heated up to 90 oC under vigorous stirring until the solution became clear. Aqueous ZnTFS (Zn(CF3SO3)2) solution electrolyte is 2M ZnTFS aqueous solution (PH: 5.4). ZnTFS gel polymer electrolytes in this work include 2M ZnTFS-PVA gel electrolyte and 2M ZnTFS-0.2M


6

Page 7 of 30 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


MnCl2-PVA gel electrolyte, respectively. The preparation process of ZnTFS gel is similar to that of ZnCl2 gel with the difference of employed Zn salts.

Data Process The specific capacity C (mAh/g) of Zn cable batteries in two-electrode configuration were calculated according to the equation: C = I∙∆t/m where I was the discharging current, Δt was the discharging time and m was the MnO2 mass. Energy (Wh/kg) density and power density (W/kg) were calculated by using the following equations: E=∫ UdC/m = ∫ U I dt/m P=E/ t where I was the discharging current, U was the cell voltage, dt was the time differential, m was the MnO2 mass, and t was the discharging time. Results and Discussion Continuous CNT fiber has attracted significant interests owe to their light weight, excellent mechanical properties as well as high electrical conductivity, which are considered as desirable candidates for fiber devices.31-34 The CNT arrays were grown on Si wafers with a thin Fe film as the catalyst in a floating catalytic chemical-vapor-deposition (CVD) reactor. The continuous


7


Page 8 of 30

CNT fiber was prepared by directly dry spinning during CNTs growth in CVD reaction zone, which was wound and collected onto a mandrel (Figure 2a). Scanning electron microscope (SEM) image in Figure 2b shows that the diameter of CNT fiber is around of 80-100 micrometers. The CNT fiber consists of CNT bundles with the diameter of about 10 nm (Figure 2c) that is also confirmed from trasmission electron microscopy (TEM) images in Figure S1. MnO2@CNT fiber electrode was further prepared via a chronoamperometry electrochemical deposition process in 0.1 mol/L aqueous Mn(NO3)2 solution. The CNT fiber is directly used as work electrode. Pt plate and saturated calomel electrode (SCE) are count electrode and reference electrode, respectively. After MnO2 deposition for 30 min, the diameter of CNT fiber become 100-120 micrometers from Figure 2d. According to high resolution SEM images in Figure 2e and 2f, the MnO2 nanosheets were intertwined and vertically distributed on the whole surface of CNT fibers to form MnO2@CNT composite fiber.

Energy dispersive spectrometer (EDS)

mapping analysis shows the elemental Mn and O distrubuted on the CNT fiber uniformly, which confirms the uniform deposition of manganese oxide on the CNT fiber surface, as shown as in Figure 2g-2i and Figure S2. The component and crystalline structure of the MnO2@CNT fiber are revealed by X-ray diffraction (XRD) patterns and Raman spectroscopies. The strong (002) peak locating at 26.0° from XRD pattern of CNT fiber in Figure 3a exhibits a typical graphitic feature with high crystalline degree, while the diffraction peak locating at 44.5° is associated with the (100) diffraction peak from hexagonal graphite.35-36 From XRD pattern of MnO2@CNT fiber, MnO2 on the surface of CNT fiber is Arkhtenskite (ɛ-MnO2, JCPDS no. 30-0820), possessing a hexagonal phase with P63/mmc (194) space group. The broadening and low intensity of the characteristic peaks suggest the low crystalline degree of as-prepared MnO2. From the Raman


8

Page 9 of 30 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


spectra of CNT fiber in Figure 3b, all Raman peaks D line, G line, 2D line can be well distinguished. D peak at 1349 cm−1 and G peak at 1581 cm−1 represent disorder features of graphitic structures and original graphite feature, respectively. 2D peak at around 2691 cm-1 stems from the second order of the zone-boundary phonons that is closely related to the number of graphite layers in the CNT fiber.37 The Raman band at around 640 cm−1 for the MnO2@CNF can be attributed to the three major Mn-O stretching vibrations of the [MnO6] group in MnO2, which futher confirms the deposition of MnO2 on the surface of CNT fiber.38-39 MnO2@CNT fiber is further characterized by X-ray photoelectron spectroscopy (XPS) analysis (Figure 3c). The detected peak located at the binding energy of 642 eV in XPS spectra can be assigned to Mn 2p3/2, revealing that the element manganese is in the chemical state of Mn4+ from Figure 3d. The peak appearing at the binding energy of 654 eV that corresponds to Mn 2p1/2, further identifies the existence of Mn4+.40 In addition, the quantitative XPS analysis indicates that the atomic ratio of Mn to O is around 1:2, which confirms the chemical state of MnO2 that is also in accordance with the XRD results. The cable-typed Zn-MnO2 micro-battery with an open circuit voltage (OCV) of around 1.55V was constructed based on the MnO2@CNT fiber cathode and a thin Zn wire anode, and the detailed preparation was described in Experimental section. The electrochemical performance of the Zn-MnO2 cable batteries were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD). To refine the electrochemical performance of MnO2@CNT fiber electrode, we prepared MnO2@CNT fibers with various MnO2 loading weight. From our experiments, the weight ratio of MnO2 to CNT fiber is 1:1, 2:1 and 3:1 corresponding to various MnO2 deposition time of 15min, 30min and 60min (denoted as MnO2-15, MnO2-30, MnO2-60), respectively. Figure 4a shows CV curves of


9


Page 10 of 30

Zn-MnO2 cable batteries at the sweeping rate of 1mV/s in 2M aqueous ZnCl2 electrolyte solution. All CV curves show two cathodic peaks located at 1.1 and 1.3 V, and an overlapped anodic peak at 1.6-1.7 V that can be clearly observed when the sweeping rate is reduced to 0.1mV/s as shown as in Figure S3. Furthermore, Figure 4b shows the typical GCD profile of ZnMnO2 cable batteries with various MnO2 content at 0.1 A/g (0.32C). The two plateaus in the GCD curves are observed, which are consistent with the two pairs of redox peaks in CV curves. The average voltage of the first discharge flat plateau is around 1.4V, while the second discharge flat plateau is about 1.3V. Based on the charge-discharge curve of MnO2-30 electrode at 0.1 A/g (Figure S4a), the differential capacity versus voltage (dQ/dV-V) curves is obtained as shown as in Figure S4b. Two pair of redox peaks are observed in dQ/dV-V curve, revealing two consequent Faraday reaction involved during charge-discharge process. The first discharge plateau is 1.35-1.48V, and the second discharge plateau locates at 1.1-1.35V. From Figure 4b, the specific capacity of MnO2-15, MnO2-30 and MnO2-60 cathodes at 0.1 A/g are 323, 322 and 285mAh/g, respectively, which shows the superior capacity perfomrance compared with the literature (Table S1). MnO2-60 cathode shows lower specific capacity due to the MnO2 material cannot be sufficient utilized resulted from excess loading of MnO2 on the CNT fiber surface. MnO2-15 and MnO2-30 cathodes possess the close capacity. Considering the balance of capacity and MnO2 loading mass, MnO2-30 (with a MnO2 loading mass of 0.5 mg) is used as cathode to further study electrochemical performance in the following experiments. Figure 4c presents the rate performance of MnO2-30 cathode based Zn-MnO2 cable battery. The specific capacity is around 322 mAh/g at 0.1 A/g based on MnO2, which still retains 62 mAh/g when the current density is enlarged by 20 times (2A/g), demonstrating a good charge-discharge rate capability although the battery possesses one-dimension achitechture. Cycling performance is also an


10

Page 11 of 30 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


important aspect of battery for real application. The Zn-MnO2 cable battery based on aqueous ZnCl2 solution is studied by continually charge-discharge measurements. According to our experiments, the specific capacity can only be kept of 60% after 300 charge-discharge cycles as shown as in Figure S5. The capacity fading is ascribed to the loss of MnO2 material from cathode during charge-discharge process.26, 41 The coulombic efficiency of all cycles keeps in the range of 96%-100%, exhibiting no side reaction in this charge-discharge process. Considering the potential electrolyte leakage issue during consecutive bending of flexible batteries, it is regarded as a good strategy to employ gel polymer electrolyte by incorporating liquid electrolyte into the host polymer.42-43 In this work, we also use the gel polymer electrolyte to prepare flexible quasi-solid-state Zn-MnO2 cable batteries. Noteworthy, we found most widely used hydrogel polymer hosts, such as polyvinyl alcohol (PVA), gelatin and so on, would be cross-linked by high concentration divalent Zn2+ in aqueous ZnCl2 or ZnSO4 solution due to the complexation reaction between Zn2+ and hydroxyl group of polymer hosts. Thus, the ZnCl2 (or ZnSO4) hydrogel cannot be formed by the simple blending of 2mol/L Zn slat aqueous solution with polymer host. However, we observed that ZnCl2 based gel can be formed by adding LiCl, which changes the PH value of the solution and limits the crosslink reaction between Zn2+ and hydroxyl group of PVA.44-45 With LiCl-ZnCl2-PVA gel (defined as ZnCl2 gel) polymer electrolyte, the electrochemical performance of the Zn-MnO2 cable batteries was evaluated. From the CV curve at 1mV/s in Figure S6, Zn-MnO2 cable battery with ZnCl2 gel polymer electrolyte also shows two redox peaks similar to that of aqueous ZnCl2 electrolyte. Figure 4d demonstrates the GCD profiles of Zn-MnO2 cable battery based on MnO2-30@CNT fiber cathode and ZnCl2 gel polymer electrolyte. The specific capacity at 0.1 A/g is around 290 mAh/g, which is still 51mAh/g at the current density of 2A/g (6.5C), demonstrating a close


11


Page 12 of 30

capacity and rate performance to that of aqueous ZnCl2 electrolyte based battery. The specific energy plots of the Zn-MnO2 cable batteries are shown in Figure 4e. The specific energy of MnO2-30 cathode in Zn-MnO2 cable battery with aqueous ZnCl2 electrolyte is 437Wh/kg at a specific power of 100 W/kg. As the first cable-type Zn-MnO2 battery, the specific energy of MnO2 cathode is even higher than most planar Zn-MnO2 batteries (Figure 4e).25-26,

41, 46-48

Furthermore, the specific energy is 86Wh/kg when the output specific power reaches 2000 W/kg. With ZnCl2 gel polymer electrolyte, the solid-state Zn-MnO2 cable battery still shows a high specific capacity of 360Wh/Kg at 100 W/Kg, which is also larger than most reported Zn-MnO2 batteries. With respective to the cycling performance, the solid-state Zn-MnO2 cable battery shows better cyclic stability than that of aqueous electrolyte. The capacity retention is around of 75% after 300 charge-discharge cycles (Figure 4f). The improvement on cycling performance of Zn-MnO2 cable battery in gel polymer electrolyte is proposed to that the gel electrolyte can somewhat prevent the collapse and chemical dissolution of MnO2 materials from cathode .49 In addition, the prepared Zn-MnO2 cable batteries show superior flexibility, which can be bent into any degree without sacrificing electrochemical performance. From Figure 5a, the Zn-MnO2 cable battery can be wrapped around a pen that demonstrates its excellent twist performance. In order to show the Zn-MnO2 cable batteries how to work in a real application, a light emitting diode (LED) light was driven by two series connected Zn-MnO2 cable batteries as shown as in Figure 5b. To evaluate the electrochemical performance under the various bending states, the cable battery was bent from normal state (State 1) into bending state (State 2), which are shown in Figure 5c-5d. No fading on the electrochemical performance of the Zn-MnO2 cable battery was observed from Figure 5e. After 100 consecutive bending cycles, there is also no obviously variation of the charge-discharge curves for the cable battery according to Figure 5f.


12

Page 13 of 30 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


In order to further disclose the electrochemical properties of Zn-MnO2 batteries, we prepared and measured Zn-MnO2 cable batteries with various Zn salt electrolytes. Previously, primary ZnMnO2 batteries usually use alkaline electrolytes. Neutral or mild acidic aqueous electrolytes, such as aqueous ZnSO4 (or ZnCl2) solution, are now employed with the purpose of improving the cyclic stability.25-26 Recently, zinc salt with bulky anion (e.g., CF3SO3 −) based aqueous electrolyte was shown to benefit reactivity and stability of Zn-MnO2 batteries.41, 50 Therefore, we measured the electrochemical performance of the Zn-MnO2 cable batteries with zinc trifluoromethanesulfonate (Zn(CF3SO3)2, ZnTFS) based electrolytes. In addition, we found that ZnTFS would not crosslink the PVA chains because the bulky TFS- anion can stable the Zn2+ ions, therefore, the ZnTFS-PVA gel can be directly prepared by a simple blending process. Figure 6a shows the GCD curves of Zn-MnO2 cable batteries with ZnTFS-PVA gel and ZnTFSMnCl2-PVA gel electrolytes, respectively. The specific capacity of Zn-MnO2 cable battery at 0.1 A/g is 188 mAh/g in the ZnTFS-PVA gel polymer electrolyte, illustrating Zn-MnO2 cable batteries based on ZnTFS electrolytes possess less specific capacity than that in ZnCl2 based electrolytes. Taking into account that the pre-added Mn2+ in the electrolyte may suppress MnOOH dissolution and maintain the electrode integrity

26, 41

, ZnTFS-MnCl2-PVA gel that

involves 0.2M MnCl2 is also used as the electrolyte. From Figure 6a, the specific capacity of ZnMnO2 cable battery is 325 mAh/g at 0.1 A/g. The present of small anion salt (MnCl2) in ZnTFSMnCl2-PVA electrolyte leads to the obviously enhancement of the capacity, which shows similar GCD profile to that in the ZnCl2 electrolyte. However, no positive effect was observed on the cycling performance by pre-adding Mn2+ ions into the electrolyte in terms to our Zn-MnO2 cable batteries, which is shown in Figure S7. From EIS analysis in Figure 6b and Table S2, the solution resistance (Rs), interface resistance (Ri) and charge-transfer resistance (Rct) of ZnTFS-


13


Page 14 of 30

PVA based battery are larger than that of ZnTFS-MnCl2-PVA based battery. This means the small anion salt (MnCl2/ZnCl2/ZnSO4) can improve the ions transport, and thus faciliates electrochemical reaction. The GCD profile of Zn-MnO2 cable batteries in ZnTFS-PVA and ZnTFS-MnCl2-PVA gel electrolytes is quite different from Figure 6a. There are two plateaus in the discharge curve of ZnTFS-MnCl2-PVA based Zn-MnO2 batteries, which is similar with that of pure ZnCl2 electrolyte based batteries. However, only one sloped discharge plateau presents for ZnTFSPVA based Zn-MnO2 batteries. We further studied charge-discharge process from the differential capacity versus voltage (dQ/dV-V) curves of ZnTFS-PVA and ZnTFS-MnCl2-PVA electrolyte based batteries, as shown as in Figure 6c. ZnTFS-PVA electrolyte based battery shows only one pair of broaden peaks in dQ/dV-V curve, revealing one Faraday reaction process invloved in the charge-discharge process. However, the ZnTFS-MnCl2-PVA electrolyte based

battery

exhibits two sharp peaks in dQ/dV-V curve, which is similar to that of ZnCl2 based batteries (Figure S4). Figure 6d is the CV curves of Zn-MnO2 cable batteries with various electrolytes at the sweeping rate of 0.1 mV/s. Similarly, Zn-MnO2 battery in ZnTFS-PVA electrolyte shows only one pair of redox peaks while the battery in ZnTFS-MnCl2-PVA electrolyte displays only one pair of broaden peaks. Therefore, the CV curves futher confirm that the different of reation process present in pure ZnTFS based electrolytes and ZnTFS-MnCl2-PVA (or ZnCl2) based electrolytes. According to the literature

50

, MnO2 electrode in mild aqueous electrolytes

experiences a consequent H+ and Zn2+ insertion/extraction during charge-discharge process. Generally, it is believed that the specific reaction process depends on the difference of MnO2 in crystallographic polymorphs (α, β, γ, δ, λ and amorphous), which is discussed in Supporting Information (Discussion of the theoretical capacity of MnO2).

25-26, 29, 41, 51-52

However, our


14

Page 15 of 30 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


results indicate that the reaction of MnO2 cathode is also relative to the Zn salts electrolytes. Considered the much smaller size of H+ than Zn2+, the H+ insertion is easily inserted compared to Zn2+ in kinetically 50. Based on our own experiments, the complexation effect between Zn2+ and bulky anion (CF3SO3 −) in ZnTFS also limits the motion of Zn2+, which is consist with the fact that Zn2+ in the ZnTFS cannot cross-link the PVA chains during the synthesis process of ZnTFS gel. Thus, a possibility is that only the H+ insert into MnO2 cathode during charge-discharge process (MnO2 + H+ + e- ↔ MnOOH) for pure ZnTFS based batteries, which requires further confirmation from in-situ component and structure characterization besides of electrochemical analysis. Considering the architecture limits (cable-shape) and the gel nature of our cable battery that is not suitable for in-situ/ex-situ characterization, therefore, the mechnaism investigation is not invloved in this study. But we can know that the difference of discharge capacity of batteries in ZnTFS-PVA and ZnTFS-MnCl2-PVA gel electrolytes is attributed from the different chargedischarge reaction process. Figure 6e shows GCD profiles of Zn-MnO2 cable with ZnTFS-PVA gel polymer electrolyte. The specific capacity is 188 mAh/g at 0.1 A/g, and it is 45 mAh/g when the current is enlarged to 2 A/g, demonstrating the Zn-MnO2 cable battery with ZnTFS-PVA gel electrolyte also possesses the good charge-discharge rate performance. According to consecutive charge-discharge tests in Figure 6f, Zn-MnO2 cable battery with ZnTFS-PVA gel polymer electrolyte shows better cycling performance compared with that of aqueous ZnTFS and ZnTFS-MnCl2-PVA gel polymer electrolyte. After 100 charge-discharge cycles, the capacity retention is around 98%. However, the capacity retention in aqueous ZnTFS electrolyte is just 85% after 100 charge-discharge cycles. The capacity retention of Zn-MnO2 cable battery in ZnTFS-MnCl2-PVA gel polymer electrolyte is just 65%, demonstrating the pre-adding of Mn2+ shows no positive effect on the


15


Page 16 of 30

cycling performance although the specific capacity is enhanced. According to above experiments, the improvement on cycling performance comes from both the ZnTFS salt and geltype electrolyte. According to the GCD profiles, the reaction of MnO2 electrode in ZnTFS and ZnCl2 electrolyte is different. We think that the destroy of MnO2 cathode in Zn salt electrolyte with large anions during charge-discharge could be reduced.53-56 In addition, gel electrolyte benefits to buffer the stress of H+ insertion/extraction and stable the MnO2 electrode.49 Therefore, the cyclic performance of MnO2 cathode in ZnTFS-PVA gel polymer electrolyte is better than that in aqueous ZnTFS and ZnTFS-MnCl2-PVA gel electrolyte. Conclusion We developed a cable-type flexible rechargeable Zn micro-battery based on a MnO2@CNT fiber-like composite cathode and Zn thin wire anode. The specific capacity of Zn-MnO2 cable micro-battery at 0.1 A/g with aqueous ZnCl2 and ZnCl2 gel polymer electrolyte are 322 mAh/g and 290 mAh/g, corresponding to the specific energy reaches to 437Wh/kg and 360 Wh/kg, respectively. Besides, Zn-MnO2 cable micro-batteries exhibit superior flexibility, which can be folded into arbitrary shape without sacrificing electrochemical performance. Furthermore, we studied the electrochemical properties of Zn-MnO2 cable batteries in different Zn salt electrolytes. Zn-MnO2 cable battery with ZnTFS-PVA gel polymer electrolyte also exhibits high capacity (188 mAh/g), excellent rate capability and good cyclic durability. Based on GCD, CVs and dQ/dV-V measurements, we found the electrochemical behavior of MnO2 cathode during charge-discharge process is affected by the Zn salts employed in the electrolytes. This first flexible rechargeable Zn-MnO2 cable-like battery prototype exhibits superior electrochemical performance and flexibility, proposing a new approach to develop high-performance energy sotage deives for portable and wearable electronics.


16

Page 17 of 30 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


Corresponding Author Yanwei Ma a, b , * a

Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, P.R. China

b

University of Chinese Academy of Sciences, Beijing 100049, PR China

E-mail: [email protected] Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. ACKNOWLEDGMENT We acknowledge the financial support of the National Natural Science Foundation of China (Grant 51403211, 51472238, 51777200 and 51721005), Innovative-Talent Program (Institute of Electrical Engineering, Chinese Academy of Sciences), Beijing Municipal Science and Technology Commission (Grant No.Z171100000917007).

REFERENCES [1].

Nishide, H.; Oyaizu, K., Materials science - toward flexible batteries. Science 2008, 319,

737-738. [2].

Zamarayeva, A. M.; Ostfeld, A. E.; Wang, M.; Duey, J. K.; Deckman, I.; Lechene, B. P.;

Davies, G.; Steingart, D. A.; Arias, A. C., Flexible and stretchable power sources for wearable electronics. Sci. Adv. 2017, 3. [3].

Gaikwad, A. M.; Whiting, G. L.; Steingart, D. A.; Arias, A. C., Highly Flexible, Printed

Alkaline Batteries Based on Mesh-Embedded Electrodes. Adv Mater 2011, 23, 3251-3255.


17


[4].

Page 18 of 30

Gaikwad, A. M.; Arias, A. C.; Steingart, D. A., Recent Progress on Printed Flexible

Batteries: Mechanical Challenges, Printing Technologies, and Future Prospects. Energy Technol. 2015, 3, 305-328. [5].

Gaikwad, A. M.; Steingart, D. A.; Ng, T. N.; Schwartz, D. E.; Whiting, G. L., A flexible

high potential printed battery for powering printed electronics. Appl Phys Lett 2013, 102. [6].

Wang, X. W.; Wang, F. X.; Wang, L. Y.; Li, M. X.; Wang, Y. F.; Chen, B. W.; Zhu, Y.

S.; Fu, L. J.; Zha, L. S.; Zhang, L. X.; Wu, Y. P.; Huang, W., An Aqueous Rechargeable Zn//Co3O4 Battery with High Energy Density and Good Cycling Behavior. Adv Mater 2016, 28, 4904-4911. [7].

Zamarayeva, A. M.; Gaikwad, A. M.; Deckman, I.; Wang, M.; Khau, B.; Steingart, D.

A.; Arias, A. C., Fabrication of a High-Performance Flexible Silver-Zinc Wire Battery. Adv. Electron. Mater. 2016, 2. [8].

Zeng, Y. X.; Meng, Y.; Lai, Z. Z.; Zhang, X. Y.; Yu, M. H.; Fang, P. P.; Wu, M. M.;

Tong, Y. X.; Lu, X. H., An Ultrastable and High-Performance Flexible Fiber-Shaped Ni-Zn Battery based on a Ni-NiO Heterostructured Nanosheet Cathode. Adv Mater 2017, 29. [9].

Zhang, Y.; Zhao, Y.; Ren, J.; Weng, W.; Peng, H. S., Advances in Wearable Fiber-

Shaped Lithium-Ion Batteries. Adv Mater 2016, 28, 4524-4531. [10].

Wang, K.; Meng, Q. H.; Zhang, Y. J.; Wei, Z. X.; Miao, M. H., High-Performance Two-

Ply Yarn Supercapacitors Based on Carbon Nanotubes and Polyaniline Nanowire Arrays. Adv Mater 2013, 25, 1494-1498. [11].

Liu, N. S.; Ma, W. Z.; Tao, J. Y.; Zhang, X. H.; Su, J.; Li, L. Y.; Yang, C. X.; Gao, Y.

H.; Golberg, D.; Bando, Y., Cable-Type Supercapacitors of Three-Dimensional Cotton Thread Based Multi-Grade Nanostructures for Wearable Energy Storage. Adv Mater 2013, 25, 49254931. [12].

Liu, W. J.; Liu, N. S.; Shi, Y. L.; Chen, Y.; Yang, C. X.; Tao, J. Y.; Wang, S. L.; Wang,

Y. M.; Su, J.; Li, L. Y.; Gao, Y. H., A wire-shaped flexible asymmetric supercapacitor based on carbon fiber coated with a metal oxide and a polymer. J Mater Chem A 2015, 3, 13461-13467. [13].

Rao, J. Y.; Liu, N. S.; Li, L. Y.; Su, J.; Long, F.; Zou, Z. G.; Gao, Y. H., A high

performance wire-shaped flexible lithium-ion battery based on silicon nanoparticles within polypyrrole/twisted carbon fibers. RSC Advances 2017, 7, 26601-26607.


18

Page 19 of 30 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


[14].

Sun, H.; Zhang, Y.; Zhang, J.; Sun, X. M.; Peng, H. S., Energy harvesting and storage in

1D devices. Nat. Rev. Mater. 2017, 2. [15].

Li, P.; Li, J.; Zhao, Z.; Fang, Z. S.; Yang, M. J.; Yuan, Z. K.; Zhang, Y.; Zhang, Q.;

Hong, W.; Chen, X. D.; Yu, D. S., A General Electrode Design Strategy for Flexible Fiber Micro-Pseudocapacitors Combining Ultrahigh Energy and Power Delivery. Adv. Sci. 2017, 4. [16].

Liu, Y. Q.; He, K.; Chen, G.; Leow, W. R.; Chen, X. D., Nature-Inspired Structural

Materials for Flexible Electronic Devices. Chem Rev 2017, 117, 12893-12941. [17].

Cheng, F. Y.; Chen, J.; Gou, X. L.; Shen, P. W., High-power alkaline Zn-MuO(2)

batteries using gamma-MnO2 nanowires/nanotubes and electrolytic zinc powder. Adv Mater 2005, 17, 2753-2756. [18].

Espinosa, D. C. R.; Bernardes, A. M.; Tenorio, J. A. S., An overview on the current

processes for the recycling of batteries. J Power Sources 2004, 135, 311-319. [19].

Cheng, F. Y.; Zhao, J. Z.; Song, W.; Li, C. S.; Ma, H.; Chen, J.; Shen, P. W., Facile

controlled synthesis of MnO2 nanostructures of novel shapes and their application in batteries. Inorg Chem 2006, 45, 2038-2044. [20].

Gaikwad, A. M.; Zamarayeva, A. M.; Rousseau, J.; Chu, H. W.; Derin, I.; Steingart, D.

A., Highly Stretchable Alkaline Batteries Based on an Embedded Conductive Fabric. Adv Mater 2012, 24, 5071-5076. [21].

Gallaway, J. W.; Erdonmez, C. K.; Zhong, Z.; Croft, M.; Sviridov, L. A.; Sholklapper, T.

Z.; Turney, D. E.; Banerjee, S.; Steingart, D. A., Real-time materials evolution visualized within intact cycling alkaline batteries. J Mater Chem A 2014, 2, 2757-2764. [22].

Shen, Y. W.; Kordesch, K., The mechanism of capacity fade of rechargeable alkaline

manganese dioxide zinc cells. J Power Sources 2000, 87, 162-166. [23].

Manke, I.; Banhart, J.; Haibel, A.; Rack, A.; Zabler, S.; Kardjilov, N.; Hilger, A.; Melzer,

A.; Riesemeier, H., In situ investigation of the discharge of alkaline Zn-MnO2 batteries with synchrotron x-ray and neutron tomographies. Appl Phys Lett 2007, 90. [24].

Rus, E. D.; Moon, G. D.; Bai, J. M.; Steingart, D. A.; Erdonmez, C. K., Electrochemical

Behavior of Electrolytic Manganese Dioxide in Aqueous KOH and LiOH Solutions: A Comparative Study. J Electrochem Soc 2016, 163, A356-A363. [25].

Xu, C. J.; Li, B. H.; Du, H. D.; Kang, F. Y., Energetic Zinc Ion Chemistry: The

Rechargeable Zinc Ion Battery. Angew Chem Int Edit 2012, 51, 933-935.


19


[26].

Page 20 of 30

Pan, H. L.; Shao, Y. Y.; Yan, P. F.; Cheng, Y. W.; Han, K. S.; Nie, Z. M.; Wang, C. M.;

Yang, J. H.; Li, X. L.; Bhattacharya, P.; Mueller, K. T.; Liu, J., Reversible aqueous zinc/manganese oxide energy storage from conversion reactions. Nat. Energy 2016, 1. [27].

Yu, X.; Fu, Y. P.; Cai, X.; Kafafy, H.; Wu, H. W.; Peng, M.; Hou, S. C.; Lv, Z. B.; Ye, S.

Y.; Zou, D. C., Flexible fiber-type zinc-carbon battery based on carbon fiber electrodes. Nano Energy 2013, 2, 1242-1248. [28].

Li, H. F.; Liu, Z. X.; Liang, G. J.; Huang, Y.; Huan, Y.; Zhu, M. S.; Pei, Z. X.; Xue, Q.;

Tang, Z. J.; Wang, Y. K.; Li, B. H.; Zhi, C. Y., Waterproof and Tailorable Elastic Rechargeable Yarn Zinc Ion Batteries by a Cross-Linked Polyacrylamide Electrolyte. ACS nano 2018, 12, 3140-3148. [29].

Dong, L.; Ma, X.; Li, Y.; Zhao, L.; Liu, W.; Cheng, J.; Xu, C.; Li, B.; Yang, Q.-H.;

Kang, F., Extremely safe, high-rate and ultralong-life zinc-ion hybrid supercapacitors. Energy Storage Materials 2018, 13, 96-102. [30].

Wang, Z. F.; Ruan, Z. H.; Liu, Z. X.; Wang, Y. K.; Tang, Z. J.; Li, H. F.; Zhu, M. S.;

Hung, T. F.; Liu, J.; Shi, Z. C.; Zhi, C. Y., A flexible rechargeable zinc-ion wire-shaped battery with shape memory function. J Mater Chem A 2018, 6, 8549-8557. [31].

Jiang, K. L.; Li, Q. Q.; Fan, S. S., Nanotechnology: Spinning continuous carbon nanotube

yarns - Carbon nanotubes weave their way into a range of imaginative macroscopic applications. Nature 2002, 419, 801-801. [32].

Avila, A. G.; Hinestroza, J. P., Smart textiles - Tough cotton. Nature Nanotechnology

2008, 3, 458-459. [33].

Kim, J. G.; Kang, H.; Lee, Y.; Park, J.; Kim, J.; Truong, T. K.; Kim, E. S.; Yoon, D. H.;

Lee, Y. H.; Suh, D., Carbon-Nanotube-Templated, Sputter-Deposited, Flexible Superconducting NbN Nanowire Yarns. Adv Funct Mater 2017, 27. [34].

Fernandez-Toribio, J. C.; Iniguez-Rabago, A.; Vila, J.; Gonzalez, C.; Ridruejo, A.;

Vilatela, J. J., A Composite Fabrication Sensor Based on Electrochemical Doping of Carbon Nanotube Yarns. Adv Funct Mater 2016, 26, 7139-7147. [35].

Hou, J. H.; Cao, C. B.; Idrees, F.; Ma, X. L., Hierarchical porous nitrogen-doped carbon

nanosheets derived from silk for ultrahigh-capacity battery anodes and supercapacitors. ACS nano 2015, 9, 2556-2564.


20

Page 21 of 30 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


[36].

Jia, J. X.; Wang, K.; Zhang, X.; Sun, X. Z.; Zhao, H. L.; Ma, Y. W., Graphene-Based

Hierarchically Micro/Mesoporous Nanocomposites as Sulfur Immobilizers for HighPerformance Lithium-Sulfur Batteries. Chem Mater 2016, 28, 7864-7871. [37].

Ferrari, A. C.; Meyer, J. C.; Scardaci, V.; Casiraghi, C.; Lazzeri, M.; Mauri, F.; Piscanec,

S.; Jiang, D.; Novoselov, K. S.; Roth, S.; Geim, A. K., Raman spectrum of graphene and graphene layers. Phys Rev Lett 2006, 97, 187401. [38].

Ma, S. B.; Ahn, K. Y.; Lee, E. S.; Oh, K. H.; Kim, K. B., Synthesis and characterization

of manganese dioxide spontaneously coated on carbon nanotubes. Carbon 2007, 45, 375-382. [39].

Buciuman, F.; Patcas, F.; Craciun, R.; Zahn, D. R. T., Vibrational spectroscopy of bulk

and supported manganese oxides. Phys Chem Chem Phys 1999, 1, 185-190. [40].

Chou, S. L.; Cheng, F. Y.; Chen, J., Electrodeposition synthesis and electrochemical

properties of nanostructured gamma-MnO2 films. J Power Sources 2006, 162, 727-734. [41].

Zhang, N.; Cheng, F. Y.; Liu, J. X.; Wang, L. B.; Long, X. H.; Liu, X. S.; Li, F. J.; Chen,

J., Rechargeable aqueous zinc-manganese dioxide batteries with high energy and power densities. Nat Commun 2017, 8. [42].

Wang, K.; Zhang, X.; Li, C.; Sun, X. Z.; Meng, Q. H.; Ma, Y. W.; Wei, Z. X.,

Chemically Crosslinked Hydrogel Film Leads to Integrated Flexible Supercapacitors with Superior Performance. Adv Mater 2015, 27, 7451-7457. [43].

Wang, K.; Wu, H. P.; Meng, Y. N.; Zhang, Y. J.; Wei, Z. X., Integrated energy storage

and electrochromic function in one flexible device: an energy storage smart window. Energy Environ Sci 2012, 5, 8384-8389. [44].

Qiu, W. D.; Li, Y.; You, A.; Zhang, Z. M.; Li, G. F.; Lu, X. H.; Tong, Y. X., High-

performance flexible quasi-solid-state Zn-MnO2 battery based on MnO2 nanorod arrays coated 3D porous nitrogen-doped carbon cloth. J Mater Chem A 2017, 5, 14838-14846. [45].

Zeng, Y. X.; Zhang, X. Y.; Meng, Y.; Yu, M. H.; Yi, J. N.; Wu, Y. Q.; Lu, X. H.; Tong,

Y. X., Achieving Ultrahigh Energy Density and Long Durability in a Flexible Rechargeable Quasi-Solid-State Zn-MnO2 Battery. Adv Mater 2017, 29. [46].

Ramanujapuram, A.; Gordon, D.; Magasinski, A.; Ward, B.; Nitta, N.; Huang, C.;

Yushin, G., Degradation and stabilization of lithium cobalt oxide in aqueous electrolytes. Energy Environ Sci 2016, 9, 1841-1848.


21


[47].

Page 22 of 30

Zhang, N.; Cheng, F. Y.; Liu, Y. C.; Zhao, Q.; Lei, K. X.; Chen, C. C.; Liu, X. S.; Chen,

J., Cation-Deficient Spinel ZnMn2O4 Cathode in Zn(CF3SO3)(2) Electrolyte for Rechargeable Aqueous Zn-Ion Battery. J Am Chem Soc 2016, 138, 12894-12901. [48].

Trocoli, R.; La Mantia, F., An Aqueous Zinc-Ion Battery Based on Copper

Hexacyanoferrate. ChemSusChem 2015, 8, 481-485. [49].

Wang, G. M.; Lu, X. H.; Ling, Y. C.; Zhai, T.; Wang, H. Y.; Tong, Y. X.; Li, Y.,

LiCl/PVA gel electrolyte stabilizes vanadium oxide nanowire electrodes for pseudocapacitors. ACS nano 2012, 6, 10296-10302. [50].

Sun, W.; Wang, F.; Hou, S. Y.; Yang, C. Y.; Fan, X. L.; Ma, Z. H.; Gao, T.; Han, F. D.;

Hu, R. Z.; Zhu, M.; Wang, C. S., Zn/MnO2 Battery Chemistry With H+ and Zn2+ Coinsertion. J Am Chem Soc 2017, 139, 9775-9778. [51].

Kundu, D.; Adams, B. D.; Ort, V. D.; Vajargah, S. H.; Nazar, L. F., A high-capacity and

long-life aqueous rechargeable zinc battery using a metal oxide intercalation cathode. Nat. Energy 2016, 1. [52].

Xu, C.; Liao, J.; Yang, C.; Wang, R. Z.; Wu, D.; Zou, P. C.; Lin, Z. Y.; Li, B. H.; Kang,

F. Y.; Wong, C. P., An ultrafast, high capacity and superior longevity Ni/Zn battery constructed on nickel nanowire array film. Nano Energy 2016, 30, 900-908. [53].

Wei, C.; Feng, Z. X.; Scherer, G. G.; Barber, J.; Shao-Horn, Y.; Xu, Z. C. J., Cations in

Octahedral Sites: A Descriptor for Oxygen Electrocatalysis on Transition-Metal Spinels. Adv Mater 2017, 29. [54].

Zhao, Y.; Wang, L. P.; Xi, S. B.; Du, Y. H.; Yao, Q. Q.; Guan, L. H.; Xu, Z. C. J.,

Encapsulating porous SnO2 into a hybrid nanocarbon matrix for long lifetime Li storage. J Mater Chem A 2017, 5, 25609-25617. [55].

Alfaruqi, M. H.; Mathew, V.; Gim, J.; Kim, S.; Song, J.; Baboo, J. P.; Choi, S. H.; Kim,

J., Electrochemically Induced Structural Transformation in a gamma-MnO2 Cathode of a High Capacity Zinc-Ion Battery System. Chem Mater 2015, 27, 3609-3620. [56].

Alfaruqi, M. H.; Gim, J.; Kim, S.; Song, J.; Jo, J.; Mathew, V.; Kim, J., Enhanced

reversible divalent zinc storage in a structurally stable alpha-MnO2 nanorod electrode. J Power Sources 2015, 288, 320-327.


22

Page 23 of 30 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


1. CNT fiber MnO2 deposition 2. MnO2@CNT fiber

Zn wire

Electrolyte soaked separator

3. Battery Assembling Heat shrink tubing

4. Cable-like battery

Figure 1. Schematic of the preparation process of a Zn-MnO2 cable battery based on MnO2@CNT fiber cathode and Zn wire anode.


23


a

d

g

Page 24 of 30

c

b

e

h Mn

f

i O

Figure 2. Morphologies of CNT fiber and MnO2@CNT composite fiber. (a) A photography of CNT fibers that are twined onto a mandrel. (b, c) SEM images of CNT fiber with low and high magnification. (d-f) SEM images of MnO2@CNT composite fiber with various magnification. (g-i) EDS-mapping images of MnO2@CNT composite fiber with distributed Mn and O elements.


24

Page 25 of 30 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


a

b

c

d

Figure 3. (a) X-ray diffraction (XRD) patterns of CNT fiber and MnO2@CNT fiber. (b) Raman spectroscopies of CNT fiber and MnO2@CNT fiber. (c) XPS survey spectrum of MnO2@CNT composite fiber. (d) Mn2p XPS spectrum of MnO2@CNT composite fiber.


25


a

b

c

d

e

f

Page 26 of 30

Figure 4. (a) CV curves at 1 mV/s of Zn-MnO2 cable batteries based on MnO2@CNT fiber electrodes with various MnO2 deposition time (MnO2-15, MnO2-30 and MnO2-60, respectively) in aqueous ZnCl2 electrolyte. (b) Galvanostatic charge-discharge plots at 0.1A/g of MnO2@CNT fiber electrodes with various MnO2 deposition time in aqueous ZnCl2 solution electrolyte. (c) Specific capacity plots and coulombic efficiency of MnO2-30@CNT fiber electrodes at various current densities in aqueous ZnCl2 solution electrolyte. (d) Galvanostatic charge-discharge plots of MnO2-30@CNT fiber electrodes at various current densities in ZnCl2 gel polymer electrolyte. (e) Ragone plots of Zn-MnO2 batteries based on various electrolytes and Zn-MnO2 batteries with other reported cathode materials. (f) Cycling performance and coulombic efficiency of ZnCl2 gel polymer electrolyte based Zn-MnO2 cable battery.


26

Page 27 of 30 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


a

c

b

d

State 1

e

State 2

f

Figure 5. The flexibility of the Zn-MnO2 cable battery: (a) The photography of Zn-MnO2 cable battery that can be twined around a roller pen, demonstrating the excellent twist performance. (b) Two cable batteries can drive a LED light work very well. (c-d) Zn-MnO2 cable battery exhibits excellent flexibility that can be bended to any degree. State 1 is the normal state of the Zn-MnO2 cable battery, while State 2 represents the bending state as shown as in the picture. (e) GCD curves of Zn-MnO2 cable battery under different bending states. (f) GCD curves of Zn-MnO2 cable battery before and after 100 bending cycles. The cable battery was bent from State 1 to State 2, meaning one bending cycles.


27


a

b Rs

c

d

e

f

Page 28 of 30

CPE

CPE

Ri

Rct

Zw

Figure 6. (a) Galvanostatic charge-discharge plots of MnO2-30@CNT fiber electrodes based ZnMnO2 cable batteries with different electrolytes. (b) Nyquist plots of electrochemical impedance spectroscopies (EIS) of Zn-MnO2 batteries with ZnTFS-PVA and ZnTFS-MnCl2-PVA gel electrolyte, respectively. The inset shows the equivalent circuit to fit the EIS data, where Rs, Ri, Rct, CPE, and Zw represent solution resistance, interface resistance between electrolyte and


28

Page 29 of 30 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


MnO2, charge-transfer resistance, constant-phase element, and Warburg diffusion process, respectively. (c) Differential capacity versus voltage (dQ/dV-V) curves of ZnTFS-PVA and ZnTFS-MnCl2-PVA electrolyte based cable batteries. (d) CV curves of MnO2-30@CNT fiber electrodes based Zn-MnO2 cable batteries at a sweeping rate of 0.1 mV/s with different electrolytes. (e) Galvanostatic charge-discharge plots of MnO2-30@CNT fiber electrode based Zn-MnO2 cable battery at various current densities in ZnTFS-PVA gel electrolyte. (f) Cycling performance of Zn-MnO2 batteries with ZnTFS aqueous electrolyte, ZnTFS-PVA gel polymer and ZnTFS-MnCl2-PVA gel polymer electrolyte, respectively.


29


Page 30 of 30

TOC graphic


30

High-Performance Cable-Type Flexible Rechargeable Zn Battery

Recommend Documents