Highly Conductive Solid-State Hybrid Electrolytes Operating at

Article

Highly Conductive Solid-State Hybrid Electrolytes Operating at Sub-zero Temperatures Taeyoung Kwon, Ilyoung Choi, and Moon Jeong Park ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b07159 • Publication Date (Web): 28 Jun 2017 Downloaded from http://pubs.acs.org on June 29, 2017

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 free 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 accessible to all readers and 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.

ACS Applied Materials & Interfaces 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 29

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

Highly Conductive Solid-State Hybrid Electrolytes Operating at Sub-zero Temperatures

Taeyoung Kwon1, Ilyoung Choi1, and Moon Jeong Park1,2* 1

Division of Advanced Materials Science, 2Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, Korea 790-784

* Corresponding author ([email protected])

KEYWORDS: Lithium batteries, Solid-state polymer electrolytes, Surface chemistry, Porous nanoparticles, Succinonitrile

1 ACS Paragon Plus Environment


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

ABSTRACT We report a unique, highly conductive, dendrite-inhibited, solid-state polymer electrolyte platform that demonstrates excellent battery performance at sub-zero temperatures. A design based on functionalized inorganic nanoparticles with interconnected mesopores that contain surface nitrile groups is the key to this development. Solid-state hybrid polymer electrolytes based on succinonitrile (SN) electrolytes and porous nanoparticles were fabricated via a simple UV-curing process. SN electrolytes were effectively confined within the mesopores. This stimulated favorable interactions with lithium ions, reduced leakage of SN electrolytes over time, and improved membrane mechanical strength. Inhibition of lithium dendrite growth and improved electrochemical stability up to 5.2 V were also demonstrated. The hybrid electrolytes exhibited high ionic conductivities of 2 × 10−3 S cm−1 at room temperature and > 10−4 S cm−1 at sub-zero temperatures, leading to stable and improved battery performance at sub-zero temperatures. Li cells made with lithium titanate anodes exhibited stable discharge capacities of 151 mAh g-1 at temperatures below −10 °C. This corresponds to 92% of the capacity achieved at room temperature (164 mAh g-1). Our work represents a significant advance in solid-state polymer electrolyte technology, and far exceeds the performance available with conventional polymeric battery separators.


Page 2 of 29

Page 3 of 29

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 Recently, lithium-ion batteries (LIBs) have been faced with crucial safety issues. This has been driven by a significant number of failing smartphone batteries.1 Possible causes of battery explosions include exothermic reactions involving electrolytes inside the cell2 and the mechanical/thermal instability of the separator causing an internal short circuit.3,4 The need for non-flammable, mechanically robust electrolytes to replace existing commercial, liquid variants is thus rapidly emerging. Solid-state polymer electrolytes (SPEs) are promising candidates in this regard. However, their low ionic conductivities and high electrode/electrolyte interfacial resistances represent significant problems.5 This has generated significant interest in gel polymer electrolytes (GPEs) comprised of liquid electrolytes inside cross-linked polymer frameworks. GPEs offer the best features of solids (elasticity) and liquids (fast ion transport).6,7 Drawbacks of widely studied GPEs that typically contain carbonate compounds6 or poly(ethylene glycol) (PEG)6-8 include their flammability,9,10 liquid leakage from the polymer matrix (key to conductivity loss over time),11 and insufficient mechanical strength for suppression of dendrite growth.12 Development of advanced GPEs thus essentially requires the discovery of nonflammable, highly conductive liquid constituents. Succinonitrile (SN) is fascinating in this regard because of its unique features such as a high dielectric constant, good solvation capabilities, superior thermal stability, negligible flammability, and great electrochemical stability.13-17 Perhaps the most salient characteristic of SN is its inherent trans-gauche isomerism, which enables efficient ion transport in quasi-solid states.13,18 For example, lithium salt-doped SN electrolytes exhibited high ionic conductivities of over 10−3 S cm−1 at room temperature,14,15,19 substantially surpassing those of PEG electrolytes.20 3 ACS Paragon Plus Environment


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

Nevertheless, pressing challenges for SN-based GPEs include their poor mechanical properties21-24 and leakage issues,24,25 which are ascribed to the tendency of SN electrolytes to behave more like liquids as the amount of lithium salt increases.15,16 These are long-lasting shortcomings of nearly all GPEs reported thus far, and occur because the GPE structures are based on non-covalent embedding of liquid electrolytes into polymer frameworks.11,26 Moreover, almost all GPEs developed to date have not shown the possibility of operating at sub-zero temperatures. This limits their use to portable electronics. In order to improve mechanical properties of the GPE, a variety of hybrid electrolyte designs that include embedded inorganic nanofillers, i.e., SiO2,27-30 Al2O3,31,32 and TiO2 nanoparticles,33 have been proposed. These are often referred to as composite polymer electrolytes (CPEs). Due to the insulating nature of inorganic nanoparticles, the development of mechanically robust CPEs without any loss of ion transport properties is of paramount importance. Recent syntheses of functional inorganic nanoparticles that bear chemical moieties on their surfaces indicate significant potential in this area.34,35 Their surface chemistries offer the opportunity to facilitate lithium salt dissociation and revitalize the intermolecular interactions between polymeric and ionic species. 36,37 These are intimately related to ionic conductivity improvements. Unfortunately, existing research on GPEs and CPEs has neither explained how to impede the leakage of mechanically entrained liquid constituents nor demonstrated operation across a wide range of temperatures. Herein, we report a radical approach to highly conductive, mechanically robust, leakinhibited CPEs made from SN electrolytes and SiO2 nanoparticles. Our approach involves the synthesis of nitrile-functionalized SiO2 nanoparticles in order to benefit from a combination of high polarity, good chemical stability, and favorable interactions with lithium ions. The nanoparticles are designed to possess interconnected mesopores with −C≡N groups on their surfaces so that SN electrolytes can be retained via thermodynamic compatibility, thereby 4 ACS Paragon Plus Environment

Page 4 of 29

Page 5 of 29

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


impeding their leakage over time. The effective confinement of SN electrolytes within the porous morphology also leads to enhancement of the mechanical strength of the CPE towards inhibited lithium dendrite growth. The new CPE-enabled stable battery operation with lithium metal oxide electrodes across a wide temperature window, and offers good rate performance. Improved electrochemical stability were further demonstrated using the CPEs, attributed to the large nitrile-containing surface area inside the porous nanoparticles.

RESULTS and DISCUSSION Synthesis and Characterization of Functional Nanoparticles. We report a unique, solidstate hybrid electrolyte platform that uses functional SiO2 nanoparticles. The nanoparticle surfaces were functionalized with -C≡N groups that help to uniformly disperse them in the SN electrolytes and promote salt dissociation via their strong electron withdrawing nature. With particle aggregation excluded and lithium ion dissociation enhanced, one can expect improved ionic conductivities from the hybrid electrolytes. As shown in Figure 1, synthesis of nitrile-functionalized SiO2 nanoparticles was performed via hydrolysis and condensation of 3-cyanopropyl triethoxysilane. C≡N groups may exist both on the surfaces and inside the particles. However, only those at the surfaces can contribute to lithium ion transport. The number density of C≡N groups at the surface of SiO2 nanoparticles is estimated to be about 2.5 / nm2. Porous SiO2 nanoparticles that contain C≡N functional groups were synthesized by using cetyltrimethylammonium bromide (CTAB) as a directing agent. Inter-connected pores with -C≡N surfaces inside the SiO2 nanoparticles were formed after extracting the CTAB. The complete removal of CTAB is confirmed by combining thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) 5 ACS Paragon Plus Environment


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

spectroscopy (see Figure S1 in the Supporting Information). TGA thermograms indicate similar nitrile group contents of 26% and 28% for porous and non-porous CN-functionalized SiO2 nanoparticles, respectively. Hereafter, nitrile-functionalized SiO2 nanoparticles with and without pores are referred to as p-CN-SiO2 and CN-SiO2, respectively.

Figure 1. Schematic drawings describing the syntheses of CN-SiO2 and p-CN-SiO2 nanoparticles via hydrolysis and condensation of 3-cyanopropyl triethoxysilane. Mesopores were formed in p-CN-SiO2 via the micellization of CTAB. The morphologies and sizes of CN-SiO2 and p-CN-SiO2 were investigated via transmission electron microscopy (TEM). Spherical CN-SiO2 nanoparticles with an average diameter of 150 nm are shown in Figure 2a. In contrast, the bright- and dark-field TEM images of p-CN-SiO2 given in Figure 2b indicate an intriguing rough spherical shape (average diameter ca. 200 nm). Energy-filtered TEM (EFTEM) further reveals the porous morphology of p-CN-SiO2. Si atoms are mapped in green in Figure 2c. The p-CN-SiO2 sample was soaked with ionic liquid (1-hexyl-3-methylimidazolium tetrafluoroborate). The inset of Figure 2c shows an energy dispersive spectroscopy (EDS) map of the post-soaking p6 ACS Paragon Plus Environment

Page 6 of 29

Page 7 of 29

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


CN-SiO2 with Si (green) and F (red) atoms marked. The image indicates that the ionic liquid penetrates the nanoparticles, suggesting the presence of interconnected pores in p-CN-SiO2.

Figure 2. (a) Bright-field TEM image of CN-SiO2 and (b) bright- and dark-field TEM images of p-CN-SiO2. (c) EFTEM elemental map of Si (green) within p-CN-SiO2. The inset image of ionic liquid-soaked p-CN-SiO2 uses EDS to map Si (green) and F (red) atoms. (d) BET curves for CN-SiO2 and p-CN-SiO2. The inset shows the pore size distribution of p-CN-SiO2.



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 porous characteristics of p-CN-SiO2 were further investigated via N2 adsorptiondesorption and Brunauer-Emmett-Teller (BET) analysis. As shown in Figure 2d, despite the small surface area of 1.1 m2g-1 associated with CN-SiO2, p-CN-SiO2 exhibits a type IV BET isotherm38 with a large surface area of 522.8 m2g-1. This indicates the presence of mesopores with average diameter of 13 nm. Electrochemical Properties of Hybrid Electrolytes. The CN-SiO2 and p-CN-SiO2 nanoparticles were used to fabricate CPEs. Figure 3a describes CPE fabrication via rapid UVcuring. Mixing p-CN-SiO2 (or CN-SiO2), SN electrolytes, and UV-curable poly(ethylene glycol) diacrylate (PEGDA) yields homogeneous, transparent gels; subsequent UV curing results in flexible membranes. The membrane dimension is 2 cm × 2 cm × 100 µm. p-CN-SiO2 nanoparticles aid ion transport in CPEs significantly. Conventional SiO2 nanoparticles with hydroxyl surfaces (hereafter OH-SiO2) were synthesized as control samples. They are spherical with an analogous average diameter of ca. 150 nm. As shown in Figure 3b, attaching -C≡N groups to their surfaces enhances the ionic conductivities of the CPEs fourfold across the entire temperature window of interest. The benefit of mesopores in the CN-functionalized SiO2 nanoparticles with regard to further improving the ionic conductivities of hybrid membranes is evident in Figure 3b. The highest ionic conductivity achieved with CPEs that contain p-CN-SiO2 is over 2 × 10-3 S/cm at 25 °C. This is triple the conductivity observed with non-porous analogues. It should be noted here that we reach the same conclusion upon replacing the SN electrolytes by other common liquid electrolytes, i.e., tetraglyme doped with lithium salts. Dissimilar degrees of salt dissociation in CPEs represent one plausible reason for this. FT-IR was used to investigate the interactions between Li+ ions and -C≡N groups (from both SN and CN-functionalized SiO2 nanoparticles). Figure 3c shows the IR spectra of three 8 ACS Paragon Plus Environment

Page 8 of 29

Page 9 of 29

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


different CPEs based on OH-SiO2, CN-SiO2, and p-CN-SiO2 nanoparticles. It shows the spectral characteristics within the C≡N stretching region. The absorption band at 2255 cm-1 indicates free nitrile groups, while the blue-shifted peak at 2280 cm-1 is attributed to the vibrational frequency of the C≡N bound to Li+, as confirmed by theoretical calculations in literature.39 The degree of salt dissociation of a CPE based on OH-SiO2 nanoparticles is as low as 30.7%. This increases to 39.3% upon attaching nitrile groups to the nanoparticle surfaces. This effect is made more pronounced when the C≡N surface area is increased via the introduction of mesopores. This increases the salt dissociation to 56.5% for the CPE with p-CN-SiO2, and may be responsible for its improved ionic conductivity. In addition to enhanced ion transport, p-CN-SiO2 mesopores offer improved electrochemical stability of CPEs, as measured via linear sweep voltammetry using stainless steel as the working electrode and lithium foil for the counter and reference electrodes. The stability range of a CPE made from CN-SiO2 is 0.30−4.8 V (vs. Li/Li+) at a sweep rate of 1 mV s-1 and at 25 °C. Figure 4a shows electrochemical stability up to 5.2 V and no oxidative or reductive reaction as low as 0.15 V with the CPE based on p-CN-SiO2. This suggests potential uses of the new CPE for high-voltage cathode materials in LIBs. We further performed galvanostatic lithium plating and stripping tests on the CPEs in symmetrical lithium cells at a current density of 0.1 mA cm-2 and 25 °C. As shown in Figure 4b, the cell consisted of CPE with CN-SiO2 exhibits an unstable high voltage profile. In contrast, the over-potential decreases significantly with p-CN-SiO2. This may be ascribed to the enhanced ionic conductivity and favorable interfacial properties of the CPE with a large C≡N surface area. It can be inferred that the design of hybrid electrolyte membranes should include porous functional inorganic fillers in order to inhibit the growth of lithium dendrites and ensure the safe operation of lithium metal-based batteries. In Figure S2 of Supporting 9 ACS Paragon Plus Environment


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

Information, we show scanning electron microscope images of Li metals and impedance data of the symmetric lithium cells with CN-SiO2 and p-CN-SiO2 as a result of galvanostatic lithium plating/stripping tests. A smooth surface of Li metal and non-significant changes in impedance profiles were evident for the cells with the CPE based on p-CN-SiO2.

Figure 3. (a) Schematic illustration of CPE fabrication using p-CN-SiO2 nanoparticles and UV-curing. (b) Ionic conductivities and (c) FT-IR spectra of three different SN-based CPEs composed of OH-SiO2, CN-SiO2, p-CN-SiO2 nanoparticles.


Page 10 of 29

Page 11 of 29

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 4. (a) Linear sweep voltammograms of CPEs that contain CN-SiO2 and p-CN-SiO2 at 1 mV s-1 and 25 °C. (b) Time-dependent voltage profiles of Li/CPE/Li cells that contain CNSiO2 and p-CN-SiO2 at a current density of 0.1 mA cm-2 and 25 °C. (c) Time-dependent ionic conductivities of CPEs with CN-SiO2 and p-CN-SiO2 at 70 °C. The conductivity is normalized by the value obtained after 0.5 h of stabilization. 11 ACS Paragon Plus Environment


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 mesopores in p-CN-SiO2 enable effective confinement of liquid-like SN electrolytes by combining significant free volumes with good CN surface thermodynamic compatibility. This should help to prevent the leakage of SN electrolytes from the CPEs. Figure 4c shows the ionic conductivities of the CPEs as functions of time. The results are normalized by the values obtained after 0.5 h of stabilization. The conductivities of CPEs that contain p-CN-SiO2 remain stable for 16 d at 70 °C above melting point of SN. These results are in sharp contrast to those from the CPE with CN-SiO2, where the conductivity rapidly decreases by about 25% over 1 d. Thermal and Mechanical Stabilities of Hybrid Electrolytes. Since battery safety is of paramount importance, it is important that CPEs exhibit mechanical and thermal stability. While both CPEs based on CN-SiO2 and p-CN-SiO2 are flexible and self-supporting, Figure 5a shows that CPEs made from p-CN-SiO2 exhibit better tensile strengths and strains than non-porous analogues. This may stem from the ability of free volumes in the p-CN-SiO2 to absorb SN electrolytes and highlights the toughness of cross-linked PEG frameworks. Note that both CPEs display flame retardant characteristics (shown in inset photograph and movie clip is provided in Supporting Information). The CPEs based on p-CN-SiO2 also exhibit excellent thermal stabilities at high temperatures. Figure 5b shows photographs of CPEs made from p-CN-SiO2 at various temperatures. No significant changes in their sizes and shapes are noted at 150 °C. This is attributed to the large surface area of p-CN-SiO2, which reduced thermal resistance and helped heat dissipation. In contrast, commercial separator Celgard 2400 cannot maintain its original shape at temperatures above 100 °C. These new hybrid electrolytes would open up the possibility of replacing LIB separators in order to reduce cost and increase stability.


Page 12 of 29

Page 13 of 29

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 5. (a) Stress-strain responses of CPEs made from CN-SiO2 and p-CN-SiO2 at a strain rate of 2.7 × 10-3 s-1, and at 25 °C. Inset photograph in (a) displays the flame retardant characteristics of the CPEs. (b) Photographs of the CPE with p-CN-SiO2 exhibiting dimensional stability up to 150 °C. The results produced by commercial separator Celgard 2400 are shown as a control.



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

Battery Performance. These positive attributes of p-CN-SiO2 CPEs aid significantly in improving battery performance. Lithium cells containing Li-metal foil, the CPE, and lithium titanate (LTO) (or lithium cobalt(III) oxide (LCO)) in carbon black were prepared and their galvanostatic discharge/charge cycle properties were investigated. Figure 6a shows the cell voltage profiles during the first discharge/charge cycle. The cells were cycled between 1.0 and 2.6 V at 0.4 C (for LTO, 1C = 175 mA g-1) and at 3.0 − 4.2 V at 0.4 C (for LCO, 1C = 150 mA g-1) at 25 °C. The results from cells containing CN-SiO2–based CPEs are shown for comparison. Plateaus at 1.55 V (vs. Li/Li+) and 1.59 V during discharging and charging, respectively, were identified for Li/CPE/LTO cells. Plateaus of 3.90 V and 3.95 V can be discerned from the discharge and charge curves of Li/CPE/LCO cells. Remarkably, Li cells based on p-CN-SiO2 CPEs exhibit significantly less polarized voltage profiles and high initial discharge capacities of 164 mAh g-1 and 140 mAh g-1 for the LTO and the LCO, respectively. This contrasts with 155 mAh g-1 and 109 mAh g-1 for the CN-SiO2-based cells. Such differences become more discernible upon cycling the cells at various C-rates. Representative data from Li/CPE/LTO cells is plotted in Figure 6b. The discharge capacities of Li cells with p-CN-SiO2 decrease with increasing C-rate. The discharge capacities are 164 mAh g-1, 163 mAh g-1, 162 mAh g-1, 161 mAh g-1, and 158 mAh g-1 at 0.4 C, 0.6 C, 0.8 C, 1C, and 2C, respectively, with > 99% Columbic efficiency. This is in sharp contrast to the considerable reductions in discharge capacities seen with CN-SiO2–based CPE under the same cycling conditions, i.e., 155 mAh g-1 (0.4C), 147 mAh g-1 (0.6C), 145 mAh g-1 (0.8C), 143 mAh g-1 (1C), and 140 mAh g-1 (2C). As shown in Figure 6c, LTO/LCO full cell with p-CN-SiO2 CPEs also exhibit good cyclability. The cell delivers a reversible discharge capacity of 132 mAh g-1 after 150 cycles (capacity fade ratio per cycle of 0.05%) with Columbic efficiency of over 99% throughout.


Page 14 of 29

Page 15 of 29

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 6. (a) Representative galvanostatic charge/discharge voltage profiles of Li/LCO and Li/LTO half-cells with CPEs composed of CN-SiO2 and p-CN-SiO2, cycled at 0.4C and at 25 °C. (b) Rate performance of the cell made from Li/CPE with p-CN-SiO2/LTO, compared to that of Li/CPE with CN-SiO2/LTO. (c) Discharge/charge capacities and Coulombic efficiencies of the LTO/ CPE with p-CN-SiO2/LCO full cell at 0.4 C for 150 cycles.



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

Another urgent requirement for future LIB electrolytes is low-temperature (sub-zero temperature) viability. As shown in Figure 7a, the CN-SiO2 CPE exhibits a significant reduction in ionic conductivity when cooled below room temperature. This is ascribed to crystallization of SN. This decline is less prominent with the p-CN-SiO2, which exhibits high ionic conductivities of 3.5 × 10-4 S cm-1 at 0 °C, 1.7 × 10-4 S cm-1 at −10 °C, and 0.9 × 10-4 S cm-1 at −20 °C. This is in sharp contrast to the low ionic conductivity of the CPE with CNSiO2 (4.5 × 10-5 S cm-1 at 0 °C and 1.6 × 10-5 S cm-1 at −10 °C). At −20 °C, the resistance of the CPE comprising CN-SiO2 increases to such an extent that the ionic conductivity measurement cannot be performed. This implies that the p-CN-SiO2 mesopores with nitrile surfaces undergo attractive intermolecular interactions with SN and lithium salts. This is a means of suppressing the crystallization of SN electrolytes (see Figure S3 of Supporting Information) and concurrently promoting Li+ ion transport in CPEs. It is noted here that the electrochemical stability of CPEs at sub-zero temperatures was confirmed by linear sweep voltammograms (Figure S4 of Supporting Information). The wide electrochemical stability window of 0.05 − 5.47 V (vs. Li/Li+) was determined for the CPE based on p-CN-SiO2 at 1 mV s-1 and at -10 °C, compared with 0.10 − 5.04 V of the CNSiO2-based CPE. It is also worthwhile to note that the CPEs with p-CN-SiO2 demonstrated good mechanical stability at sub-zero temperatures (Figure S5 of Supporting Information). The CPE with p-CN-SiO2 remained intact after repeated bending and stretching tests at -10 °C. This is in sharp contrast to the results of the CN-SiO2-based CPE, which was broken into two pieces within a few cycles, attributed to the crystallization of SN electrolytes. The CPEs based on p-CN-SiO2 thus offer notable Li cell cycling performance at subzero temperatures. Representative results obtained using Li/CPE/LTO half-cells are shown in 16 ACS Paragon Plus Environment

Page 16 of 29

Page 17 of 29

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


Figures 7b and 7c. There were no significant changes in the lithiation/de-lithiation plateaus. Cycling at -10 °C causes a discharge capacity reduction, but the value remains high at 151 mAh g-1 after 50 cycles. The electrochemical impedance spectroscopy data of Li/CPE/LTO cell at different temperatures are provided in Figure S6 of Supporting Information. Based on the results obtained thus far, we have reached the conclusion that introducing porous inorganic nanoparticles with functional surfaces into polymer electrolytes produces a variety of positive effects in lithium batteries. It facilitates lithium salt dissociation, improves mechanical/thermal/electrochemical stability, and enhances ionic conductivity across a wide temperature window. The results presented above represent significant advances in solid-state polymer electrolytes.



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

Page 18 of 29

Figure 7. (a) Ionic conductivities of CPEs with CN-SiO2 and p-CN-SiO2 across a wide temperature window. (b) Representative galvanostatic discharge/charge voltage profiles of Li/CPE with p-CN-SiO2/LTO, cycled at 1.0−2.6 V at 0.4C and 25 °C. (c) The discharge capacities and Columbic efficiencies of Li/CPE with p-CN-SiO2/LTO after 50 cycles at 25 °C and −10 °

18

ACS Paragon Plus Environment

Page 19 of 29

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


CONCLUSIONS We demonstrated that introducing porous, nitrile-functionalized SiO2 nanoparticles into SN-based electrolytes leads to (1) facilitation of lithium salt dissociation (56.5%) via favorable interactions between –C≡N groups and Li+ ions, (2) improved ionic conductivity in the broad temperature window of interest (2 × 10-3 S cm-1 at room temperature and > 10-4 S cm-1 at sub-zero temperatures), (3) confinement of SN electrolytes within the nanoparticle pores, thus increasing the mechanical properties of the material (tensile strength ~ 4 MPa) and

preventing

leakage

even

over the melting point

of

SN,

(4)

enhanced

thermal/electrochemical stability (up to 150 °C and 5.2 V), (5) inhibition of lithium dendrite growth, and (6) improved charge/discharge capacities and noteworthy rate performance. The aforementioned positive characteristics of CPEs will ultimately lead to breakthroughs in solid-state polymer electrolytes. For example, battery tests using Li/CPE/LTO half cells revealed stable discharge capacities of 164 mAh g-1 (0.4 C) and 158 mAh g-1 (2 C) at 25 °C. These discharge capacities are considerably higher than those of cells based on non-porous CN-SiO2. LTO/CPE/LCO full cell also exhibited good cyclability with capacity fade ratio per cycle of 0.05% for 150 cycles. In particular, p-CN-SiO2 inhibited crystallization of SN electrolytes, thus enabling stable battery operation with lithium metal oxide electrodes at sub-zero temperatures.

EXPERIMENTAL SECTION Synthesis of Nitrile-functionalized Silica Nanoparticles (CN-SiO2). CN-SiO2 was synthesized by the hydrolysis and condensation of 3-cyanopropyl triethoxysilane (3CP-TES). 5 mL (0.02 mol) of 3CP-TES was dissolved in ethanol (HPLC grade, J.T. Baker, 75 mL), followed by dropwise addition of 7.5 mL (0.06 mol) of ammonia hydroxide (28~30%, 19 ACS Paragon Plus Environment


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 20 of 29

Samchun Co.). The reaction mixtures were stirred overnight at room temperature and the resultant turbid solution was centrifuged at 4500 rpm. CN-SiO2 was obtained after rinsing with deionized water/ethanol and vacuum drying at 80 °C. Synthesis of Porous Nitrile-functionalized Silica Nanoparticles (p-CN-SiO2). In order to synthesize p-CN-SiO2, 1 mL (0.004 mol) of 3CP-TES, 0.9 g (0.0025 mol) of cetyltrimethylammonium bromide (CTAB, Sigma Aldrich), and 2 mL (0.005 mol) of 1,2bis(triethoxysilyl)ethane (Sigma Aldrich) were dissolved in 150 mL of ethanol. 6 mL (0.05 mol) of ammonia hydroxide was dropped into the reaction mixtures under stirring at 60 °C. The product was centrifuged at 4500 rpm and the CTAB was extracted by stirring in the mixtures of hydrochloric acid (36%, Alfa Aesar, 5 mL) and ethanol (150 mL) overnight at 60 °C. The resultant white powder was rinsed with deionized water/ethanol and vacuum-dried at 80 °C. The complete removal of organic moieties in p-CN-SiO2 was confirmed by thermogravimetric analysis (TGA, Q50, TA instruments). Characterization of CN-SiO2 and p-CN-SiO2 Nanoparticles. The determination of nitrile groups in CN-SiO2 and p-CN-SiO2 was performed by combining Fourier transform infrared spectroscopy (FT-IR, Spectrum twoTM, PerkinElmer) and TGA (Q50, TA instruments). The morphologies of CN-SiO2 and p-CN-SiO2 were elucidated by using scanning transmission electron microscopy (STEM, JEOL JEM-2100F) and high-resolution transmission electron microscopy (HR-TEM, JEOL JEM-2200FS), equipped with electron energy loss spectroscopy (EELS). The interconnected mesopores in p-CN-SiO2 were further confirmed by

energy

dispersive

spectroscopy

(EDS)

mapping

after

infiltrating

1-hexyl-3-

methylimidazolium tetrafluoroborate, Sigma Aldrich). Specific surface areas and porous structures of p-CN-SiO2 were investigated by Brunauer-Emmit-Teller (BET) method. Preparation of Composite Polymer Electrolyte Membranes (CPEs). 3.4 M of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI, 98%, TCI) was dissolved in succinonitrile (SN, 20 ACS Paragon Plus Environment

Page 21 of 29

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


99%, Sigma Aldrich). The SN electrolytes, CN-SiO2 (or p-CN-SiO2), and polyethylene glycol diacrylate (PEGDA, Mn = 700, Sigma Aldrich) were mixed at a weight ratio of 20:60:20. Two photoinitiators, 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP, Sigma Aldrich) and Lucirin® TPO (BASF), were added to the mixtures where the amount of HMPP/TPO was approximately 1 wt% of PEGDA. The mixtures were ball-milled for 1 h and cast on a polyethylene terephthalate substrate. Upon exposure to UV lamp (Phoseon, 2000 mW cm-2) for 3 min, free-standing CPEs with thickness of ca. 100 µm were obtained. To avoid the issues of water contamination on hygroscopic samples, all fabrication procedures were performed in argon-filled glove box. Characterization of CPEs. Tensile strength of the CPEs were measured using nano universal testing machine (Nano UTM, MTS Nano Instruments, USA) at a strain rate of 2.7 × 10-3 s-1. Dimensional stability of the CPEs (3 cm × 3 cm × 100 µm) was investigated by heating the samples up to 150 °C on a hot-plate. Commercially available polyolefin separator (Celgard 2400) was used as a control. Through-plane ionic conductivities of the CPEs were measured using AC impedance spectroscopy (VersaSTAT3, Princeton Applied Research, AMETEK Inc.). Two-probe cell used consists of stainless steel blocking electrodes and Pt working/counter electrodes. Electrochemical stability of the CPEs were examined by linear sweep voltammetry (LSV) upon sandwiching them between lithium metal and stainless steel electrodes at a scan rate of 1 mV s-1 and at 25 °C. All characterizations were performed in argon-filled glove box. Fabrication of Half Cells and Full Cells. For the preparation of LTO anode, 80 wt% of lithium titanate, spinel (Sigma Aldrich), 10 wt% of Super P carbon (Alfa Aesar) and 10 wt% of PVDF (Solef) binder in N-methyl-2-pyrrolidone (Sigma Aldrich) were ball-milled and casted onto a Cu-foil current collector by a doctor-blade method. LCO cathode was prepared 21 ACS Paragon Plus Environment


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

by the same method using lithium cobalt (III) oxide (Alfa Aesar), Super P carbon, and PVDF in weight ratio of 80:15:5 and an Al-foil current collector. Both LTO and LCO electrodes were dried at 50 °C for 24 h under Ar-blanket, followed by vacuum drying for 48 h. LTO loading of 1.65 mg cm-2 and LCO loading of 1.60 mg cm-2 were determined. The dried electrodes were cut to a diameter of 15 mm and coin type cells (CR2032, MTI) were fabricated in a high-purity Ar-filled glove box. Galvanostatic discharge/charge tests of half cells and full cells were performed using a battery cycler (WBCS3000, Wonatech).

Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Characterization of materials by FT-IR, SEM, DSC, bending/stretching tests, and EIS experiments, including Figures S1−S6 and movie clip showing flame retardant characteristics.

Author Information Corresponding Authors [email protected] ORCID Moon Jeong Park: 0000-0003-3280-6714

Notes The authors declare no competing financial interest.

Acknowledgements This work was financially supported by This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. NRF2017R1A2B3004763) and the Global Frontier R&D program on Center for Multiscale


Page 22 of 29

Page 23 of 29

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 System through the National Research Foundation of Korea, funded by the Ministry of Education, Science and Technology.



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

REFERENCES (1) Consumer Reports. Samsung Investigation Reveals New Details About Note7 Battery Failures,

http://www.consumerreports.org/smartphones/samsung-investigation-new-

details-note7-battery-failures, 2017. (2) Inoue, T.; Mukai, K. Are All-Solid-State Lithium-Ion Batteries Really Safe?Verification by Differential Scanning Calorimetry with an All-Inclusive Microcell. ACS Appl. Mater. Interfaces 2017, 9, 1507-1515. (3) Orendorff, C. J.; Lambert, T. N.; Chavez, C. A.; Bencomo, M.; Fenton, K. R. Polyester Separators for Lithium-Ion Cells: Improving Thermal Stability and Abuse Tolerance. Adv. Energy Mater. 2013, 3, 314-320. (4) Cannarella, J.; Liu, X.; Leng, C. Z.; Sinko, P. D.; Gor, G. Y.; Arnold, C. B. Mechanical Properties of a Battery Separator under Compression and Tension. J. Electrochem. Soc. 2014, 161, F3117-F3122. (5) Bhattacharyya, A. J.; Fleig, J.; Guo, Y.-G.; Maier, J. Local Conductivity Effects in Polymer Electrolytes. Adv. Mater. 2005, 17, 2630-2634. (6) Song, J. Y.; Wang, Y. Y.; Wan, C. C. Review of Gel-Type Polymer Electrolytes for Lithium-Ion Batteries. J. Power Sources 1999, 77, 183-197. (7) Huang, W.; Zhu, Z.; Wang, L.; Wang, S.; Li, H.; Tao, Z.; Shi, J.; Guan, L.; Chen, J. Quasi-Solid-State Rechargeable Lithium-Ion Batteries with a Calix[4]quinone Cathode and Gel Polymer Electrolyte. Angew. Chem. 2013, 125, 9332-9336. (8) Lu, Q.; Fang, J.; Yang, J.; Miao, R.; Wang, J.; Nuli, Y. Novel Cross-Linked Copolymer Gel Electrolyte Supported by Hydrophilic Polytetrafluoroethylene for Rechargeable Lithium Batteries. J. Membr. Sci. 2014, 449, 176-183. (9) Akashi, H.; Sekai, K.; Tanaka, K.-I. A Novel Fire-Retardant Polyacrylonitrile-Based Gel Electrolyte for Lithium Batteries. Electrochim. Acta 1998, 43, 1193-1197. (10) Morford, R. V.; Kellam, E. C.; Hofmann, M. A.; Baldwin, R.; Allcock, H. R. A FireResistant Organophosphorus Gel Polymer Electrolyte Additive for Use in Rechargeable Lithium Batteries. Solid State Ionics 2000, 133, 171-177. 24 ACS Paragon Plus Environment

Page 24 of 29

Page 25 of 29

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


(11) Tong, Y.; Xu, Y.; Chen, D.; Xie, Y.; Chen, L.; Que, M.; Hou, Y. Deformable and Flexible Electrospun Nanofiber-Supported Cross-Linked Gel Polymer Electrolyte Membranes for High Safety Lithium-Ion Batteries. RSC Adv. 2017, 7, 22728-22734. (12) Lu, Q.; He, Y.-B.; Yu, Q.; Li, B.; Kaneti, Y. V.; Yao, Y.; Kang, F.; Yang, Q.-H. Dendrite-Free, High-Rate, Long-Life Lithium Metal Batteries with a 3D Cross-Linked Network Polymer Electrolyte. Adv. Mater. 2017, 29, 1604460. (13) Long, S.; MacFarlane, D. R.; Forsyth, M. Fast Ion Conduction in Molecular Plastic Crystals. Solid State Ionics 2003, 161, 105-112. (14) Alarco, P.-J.; Abu-Lebdeh, Y.; Abouimrane, A.; Armand, M. The Plastic-Crystalline Phase of Succinonitrile as a Universal Matrix for Solid-State Ionic Conductors. Nat. Mater. 2004, 3, 476-481. (15) Echeverri, M.; Kim, N.; Kyu, T. Ionic Conductivity in Relation to Ternary Phase Diagram

of

Poly(ethylene

oxide),

Succinonitrile,

and

Lithium

Bis(trifluoromethane)sulfonamide Blends. Macromolecules, 2012, 45, 6068-6077. (16) Das, S.; Prathapa, S. J.; Menezes, P. V.; Guru Row, T. N.; Bhattacharyya, A. J. Study of Ion Transport in Lithium Perchlorate-Succinonitrile Plastic Crystalline Electrolyte via Ionic Conductivity and in Situ Cryo-Crystallography. J. Phys. Chem. B 2009, 113, 50255031. (17) Hu, P.; Chai, J.; Duan, Y.; Liu, Z.; Cui, G.; Chen, L. Progress in Nitrile-Based Polymer Electrolytes for High Performance Lithium Batteries. J. Mater. Chem. A 2016, 4, 1007010083. (18) Fan, L.-Z.; Hu, Y.-S.; Bhattacharyya, A. J.; Maier, J. Succinonitrile as a Versatile Additive for Polymer Electrolytes. Adv. Funct. Mater. 2007, 17, 2800-2807. (19) Ha, H.-J.; Kwon, Y. H.; Kim, J. Y.; Lee, S.-Y. A Self-Standing, UV-Cured Polymer Networks-Reinforced Plastic Crystal Composite Electrolyte for a Lithium-Ion Battery. Electrochim. Acta 2011, 57, 40-45. (20) Echeverri, M.; Hamad, C.; Kyu, T. Highly Conductive, Completely Amorphous Polymer Electrolyte Membranes Fabricated through Photo-Polymerization of Poly(ethylene 25 ACS Paragon Plus Environment


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

glycol diacrylate) in Mixtures of Solid Plasticizer and Lithium salt. Solid State Ionics 2014, 254, 92-100. (21) Patel, M.; Chandrappa, K. G.; Bhattacharyya, A. J. Increasing Ionic Conductivity and Mechanical Strength of a Plastic Electrolyte by Inclusion of a Polymer. Electrochim. Acta 2008, 54, 209-215. (22) Ha, H.-J.; Kil, E.-H.; Kwon, Y. H.; Kim, J. Y.; Lee, C. K.; Lee, S.-Y. UV-Curable SemiInterpenetrating Polymer Network-Integrated, Highly, Bendable Plastic Crystal Composite Electrolyte for Shape-Conformable All-Solid-State Lithium Ion Batteries. Energy Environ. Sci. 2012, 5, 6491-6499. (23) He, R.; Echeverri, M.; Ward, D.; Zhu, Y.; Kyu, T. Highly Conductive Solvent-Free Polymer Electrolyte Membrane for Lithium-Ion Batteries: Effect of Prepolymer Molecular Weight. J. Membr. Sci. 2016, 498, 208-217. (24) Choi, K.-H.; Cho, S.-J.; Kim, S.-H.; Kwon, Y. H.; Kim, J. Y.; Lee, S.-Y. Thin, Deformable, and Safety-Reinforced Plastic Crystal Polymer Electrolytes for HighPerformance Flexible Lithium-Ion Batteries. Adv. Funct. Mater. 2014, 24, 44-52. (25) Suleman, M.; Kumar, Y.; Hashmi, S. A. Structural and Electrochemical Properties of Succinonitrile-Based Gel Polymer Electrolytes: Role of Ionic Liquid Addition. J. Phys. Chem. B 2013, 117, 7436-7443. (26) Kuo, P.-L.; Wu, C.-A.; Lu, C.-Y.; Tsao, C.-H.; Hsu, C.-H.; Hou, S.-S. High Performance of Transferring Lithium Ion for Polyacrylonitrile-Interpenetrating Crosslinked Polyoxyethylene Network as Gel Polymer Electrolyte. ACS Appl. Mater. Interfaces 2014, 6, 3156-3162. (27) Choi, I. Y.; Kim, H.; Park, M. J. Making a Better Organic-Inorganic Composite Electrolyte to Enhancer the Cycle Life of Lithium-Sulfur Batteries. RSC. Adv. 2014, 4, 61333-61336. (28) Liu, K.; Ding, F.; Liu, J.; Zhang, Q.; Liu, X.; Zhang, J.; Xu, Q. A Cross-Linking Succinonitrile-Based Composite Polymer Electrolyte with Uniformly Dispersed Vinyl-


Page 26 of 29

Page 27 of 29

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


Functionalized SiO2 Particles for Li-Ion Batteries. ACS Appl. Mater. Interfaces 2016, 8, 23668-23675. (29) Zhou, D.; Liu, R.; He, Y.-B.; Li, F.; Liu, M.; Li, B.; Yang, Q.-H.; Cai, Q.; Kang, F. SiO2 Hollow Nanosphere-Based Composite Solid Electrolyte for Lithium Metal Batteries to Suppress Lithium Dendrite Growth and Enhance Cycle Life. Adv. Energy Mater. 2016, 6, 1502214. (30) Li, X.; Zhang, Z.; Yin, K.; Yang, L.; Tachibana, K.; Hirano, S.-I. Mesoporous Silica/Ionic Liquid Quasi-Solid-State Electrolytes and their Application in Lithium Metal Batteries. J. Power Sources 2015, 278, 128-132. (31) Tan, R.; Gao, R.; Zhao, Y.; Zhang, M.; Xu, J.; Yang, J.; Pan, F. Novel OrganicInorganic Hybrid Electrolyte to Enable LiFePO4 Quasi-Solid-State Li-Ion Batteries Performed Highly around Room Temperature. ACS Appl. Mater. Interfaces 2016, 8, 31273-31280. (32) Klongkan, S.; Pumchusak, J. Effects of Nano Alumina and Plasticizers on Morphology, Ionic Conductivity, Thermal and Mechanical Properties of PEO-LiCF3SO3 Solid Polymer Electrolyte. Electrochim. Acta 2015, 161, 171-176. (33) Croce, F.; Curini, R.; Martinelli, A.; Persi, L.; Ronci, F.; Scrosati, B. Physical and Chemical Properties of Nanocomposite Polymer Electrolyte. J. Phys. Chem. B 1999, 103, 10632-10638. (34) Shin, W.-K.; Yoo, J. H.; Choi, W.; Chung, K. Y.; Jang, S. S.; Kim, D.-W. Cycling Performance of Lithium-Ion Polymer Cells Assembled with a Cross-Linked Composite Polymer Electrolyte Using a Fibrous Polyacrylonitrile Membrane and VinylFunctionalized SiO2 Nanoparticles. J. Mater. Chem. A 2015, 3, 12163-12170. (35) Cho, J.; Jung, Y.-C.; Lee, Y. S.; Kim, D.-W. High Performance Separator Coated with Amino-Functionalized SiO2 Particles for Safety Enhanced Lithium-Ion Batteries. J. Membr. Sci. 2017, 535, 151-157. (36) Sun, J.; Bayley, P.; MacFarlane, D. R.; Forsyth, M. Gel Electrolytes Based on Lithium Modified Silica Nano-Particles. Electrochim. Acta 2007, 52, 7083-7090. 27 ACS Paragon Plus Environment


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

(37) Lee, Y.-S.; Lee, J. H.; Choi, J.-A.; Yoon, W. Y.; Kim, D.-W. Cycling Characteristics of Lithium Powder Polymer Batteries Assembled with Composite Gel Polymer Electrolytes and Lithium Powder Anode. Adv. Funct. Mater. 2012, 23, 1019-1027. (38) Khalfaoui, M.; Knani, S.; Hachicha, M. A.; Ben Lamine, A. New Theoretical Expressions for the Five Adsorption Type Isotherms Classified by BET Based on Statistical Physics treatment. J. Colloid Interface Sci. 2003, 263, 350-356. (39) Yuan, K.; Bian, H.; Shen, Y.; Jiang, B.; Li, J.; Zhang, Y.; Chen, H.; Zheng, J. A. Coordination Number of Li+ in Nonaqueous Electrolyte Solutions Determined by Molecular Rotational Measurements. J. Phys. Chem. B 2014, 118, 3689-3695.


Page 28 of 29

Page 29 of 29

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


Table of Contents use only

Highly Conductive Solid-State Hybrid Electrolytes Operating at Sub-zero Temperatures

Taeyoung Kwon1, Ilyoung Choi1, and Moon Jeong Park1,2*


Highly Conductive Solid-State Hybrid Electrolytes Operating at

Recommend Documents