Cross-linked Gel Polymer Electrolyte Research Articles

Three-dimensional cross-linked network deep eutectic gel polymer electrolyte with the self-healing ability enable by hydrogen bonds and dynamic disulfide bonds

Solid polymer electrolytes (SPEs) are effective solutions for the development of high-performance and flexible lithium metal batteries (LMBs). However, the key problems of SPEs including low ionic conductivity and inability to repair damage have hindered their industrialization process. In this work, a three-dimensional (3D) cross-linked network gel polymer electrolyte (CNGPE) is designed. The addition of deep eutectic solvent (DES) improves the ionic conductivity of CNGPE. The hydrogen bonds and dynamic disulfide bonds in the 3D cross-linked network endow CNGPE rapid self-healing ability at ambient temperature. In addition, the addition of lithium difluoro(oxalato)borate (LiDFOB) and lithium nitrate (LiNO3) helps to form a stable solid electrolyte interface (SEI). Due to the ingenious design, the Li/CNGPE/Li symmetrical cell exhibits excellent interface stability and no short circuit occurs for more than 800 h. The assembled LiFePO4/CNGPE/Li cell exhibits a discharge specific capacity of 126 mAh g−1 after 960 cycles at 0.5C. This work has shown that the self-healing gel polymer electrolyte containing DES provides an effective and feasible method for the development of high-performance LMBs.

A Cross-Linked Gel Polymer Electrolyte Composed of PEGDA and Acrylonitrile for High-Voltage Lithium Metal Batteries

A Cross-Linked Gel Polymer Electrolyte Composed of PEGDA and Acrylonitrile for High-Voltage Lithium Metal Batteries

In-Situ Cross-linked F- and P-Containing Solid Polymer Electrolyte for Long-Cycling and High-Safety Lithium Metal Batteries with Various Cathode Materials.

The practical application of lithium metal batteries (LMBs) has been hindered by limited cycle-life and safety concerns. To solve these problems, we develop a novel fluorinated phosphate cross-linker for gel polymer electrolyte in high-voltage LMBs, achieving superior electrochemical performance and high safety simultaneously. The fluorinated phosphate cross-linked gel polymer electrolyte (FP-GPE) by in-situ polymerization method not only demonstrates high oxidation stability but also exhibits excellent compatibility with lithium metal anode. LMBs utilizing FP-GPE realize stable cycling even at a high cut-off voltage of 4.6 V (vs Li/Li+) with various high-voltage cathode materials. The LiNi0.6Co0.2Mn0.2O2|FP-GPE|Li battery exhibits an ultralong cycle-life of 1200 cycles with an impressive capacity retention of 80.1 %. Furthermore, the FP-GPE-based batteries display excellent electrochemical performance even at practical conditions, such as high cathode mass loading (20.84 mg cm-2), ultrathin Li (20 μm), and a wide temperature range of -25 to 80 °C. Moreover, the first reported solid-state 18650 cylindrical LMBs have been successfully fabricated and demonstrate exceptional safety under mechanical abuse. Additionally, the industry-level 18650 cylindrical LiMn2O4|FP-GPE|Li4Ti5O12 cells demonstrate a remarkable cycle-life of 1400 cycles. Therefore, the impressive electrochemical performance and high safety in practical batteries demonstrate a substantial potential of well-designed FP-GPE for large-scale industrial applications.

An in-situ cross-linked network PMMA-based gel polymer electrolyte with excellent lithium storage performance

Gel polymer electrolytes (GPEs) effectively combine the advantages of high ionic conductivity and reduce the risk of leakage associated with liquid. In this study, a chemically cross-linked gel polymer electrolyte was prepared by in-situ polymerization using polymethyl methacrylate (PMMA) as a matrix and neopentyl glycol diacrylate (NPGDA) as cross-linking agent. The cross-linked structure of the GPE was preliminarily investigated, as well as the influence of the degree of cross-linking on its physical properties. The GPE exhibited a superior conductivity of 1.391 mS cm−1 at 25 °C. Herein, the Li|GPE|LiNi0.8Co0.1Mn0.1O2 cell has an excellent capacity retention rate of 80.7% after 150 cycles at 0.5 C in addition to a high discharge specific capacity of 203 mAh g−1. The structure of the cathode material is shielded from the production of byproducts during the charging and discharging of lithium-ion batteries by the cross-linked PMMA GPE.

A strong nucleophilic fluorination agent to achieve highly stable in-situ 3D cross-linked gel polymer electrolyte for lithium-ion batteries

The Gel Polymer Electrolyte (GPE) is recognized as a promising alternative to conventional electrolytes, aiming to enhance the longevity and energy density of lithium-ion batteries (LIBs). However, several challenges persist, particularly concerning the conductivity and voltage window of GPE in battery systems. In this study, we introduce an in-situ 3D crosslinked GPE, using polymethyl methacrylate (PMMA) as the monomer and polyethylene glycol dimethacrylate (PEGDMA) as the crosslinking agent, to ensure structural stability and optimized ion conductivity. We also incorporate a potent nucleophilic fluorination agent, Tetrabutylammonium fluoride (TBAF), to augment the compatibility and oxidation resistance of the formulated FGPPE. The recurring (–CH2CH2O-) units of PEGDMA, coupled with in-situ lithium fluoride (LiF) and C-F groups introduced by TBAF, endow the FGPPE with a remarkable ionic conductivity of 7.8 mS cm−1 and a distinctly electrochemical stability of 4.65 V. Notably, the Li metal anode, featuring an F-rich solid-state interface (SEI), demonstrates uniform Li+ deposition, sustaining a cycling life of 1000 h and maintaining a commendable average coulomb efficiency of 98.5 % over 300 cycles. Additionally, the NCM811/SiC pouch cell integrated with FGPPE showcases superior cycling stability, retaining 99.4 % of its capacity after 600 cycles at an elevated voltage of 4.45 V. Such advancements in gel polymer electrolyte design can significantly expedite the commercial deployment of gel polymer Li-ion batteries.

Crosslinked Gel Polymer Electrolyte from Trimethylolpropane Triglycidyl Ether by In Situ Polymerization for Lithium-Ion Batteries.

Electrolytes play a critical role in battery performance. They are associated with an increased risk of safety issues. The main challenge faced by many researchers is how to balance the physical and electrical properties of electrolytes. Gel polymer electrolytes (GPEs) have received increasing attention due to their satisfactory properties of ionic conductivity, mechanical stability, and safety. Herein, we develop a gel network polymer electrolyte (GNPE) to address the challenge mentioned earlier. This GNPE was formed by tri-epoxide monomer and bis(fluorosulfonyl)imide lithium salt (LiFSI) via an in situ cationic polymerization under mild thermal conditions. The obtained GNPE exhibited a relatively high ionic conductivity (σ) of 2.63 × 10-4 S cm-1, lithium transference number (tLi+, 0.58) at room temperature (RT), and intimate electrode compatibility with LiFePO4 and graphite. The LiFePO4/GNPE/graphite battery also showed a promising cyclic performance at RT, e.g., a suitable discharge specific capacity of 127 mAh g-1 and a high Coulombic efficiency (>97%) after 100 cycles at 0.2 C. Moreover, electrolyte films showed good mechanical stability and formed the SEI layer on the graphite anode. This study provides a facile method for preparing epoxy-based electrolytes for high-performance lithium-ion batteries (LIBs).

Constructing Stable Solid Electrolyte Interphase Using Gel Polymer Electrolytes for Anode-Free Lithium Metal Batteries with Enhanced Cycle Life

Anode-free lithium metal batteries (AFLMBs) have recently emerged as next-generation batteries due to high energy density, reduced cost, and simplified manufacturing process due to the absence of reactive metallic lithium. However, developing high-performance AFLMBs faces several challenges for practical applications, such as low coulombic efficiency and poor cyclability, due to the dendrite growth of lithium and side reactions of lithium with liquid electrolytes. To develop the AFLMBs with long cycle life, it is necessary to attain high coulombic efficiency since there is no excessive lithium to compensate for irreversible Li inventory losses in the AFLMB. Three-dimensional cross-linked gel polymer electrolyte (GPE) can be a good candidate for stabilizing the lithium metal by encapsulating organic solvents in the polymer matrix, leading to reduction of the parasitic reactions between lithium metal and liquid electrolyte, which results in high coulombic efficiency of AFLMBs. In this work, we prepared a cross-linked GPE using a multi-functional cross-linking agent to realize high coulombic efficiency and long cycle life of AFLMBs with LiNixCoyAl1-x-yO2(NCA) cathode (areal capacity of 4.76 mAh cm-2). Moreover, the GPE capable of coordinating with lithium ions could construct stable solid electrolyte interphase by regulating lithium ion solvation structures. Cycling performance was investigated in the voltage range of 3.6 – 4.3 V at 0.5 C rate. The Cu/GPE/NCA cell exhibited a capacity retention of 80% after 150 cycles, which was higher than that of AFLMB with liquid electrolyte. Electrochemical characterization and spectrometry were performed to investigate how the GPE could improve the cycling performance of AFLMBs.

Nonflammable Gel Polymer Electrolyte for Lithium-Ion Batteries with Enhanced Safety and High-Temperature Performance

Lithium-ion batteries (LIBs) have become dominant power sources for various applications such as mobile electronics, electric vehicles and energy storage systems. However, liquid electrolytes currently used in LIBs have critical drawbacks such as flammability and leakage problem. In this regard, various electrolyte systems have been developed to enhance the battery safety while maintaining cycling performance. Among them, the chemically cross-linked gel polymer electrolytes (GPEs) can enhance the thermal safety of LIBs by effectively encapsulating organic solvents in the polymer matrix. However, they usually contain large amounts of organic solvents to achieve high ionic conductivity, making GPE be still flammable. To solve these problems, we designed and synthesized a novel phosphorus-based cross-linking agent with excellent flame retardancy. GPE was prepared by in-situ thermal curing of gel precursor containing liquid electrolyte and phosphorus-based cross-linking agent. The obtained GPE exhibited high ionic conductivity and nonflammability. The GPE was applied to lithium-ion cells composed of graphite anode and LiNi0.6Co0.2Mn0.2O2 cathode. Our results revealed that the lithium-ion cell employing GPE exhibited enhanced safety and improved high-temperature cycling performance compared to the cell with the liquid electrolyte.

Dual-type gel polymer electrolyte for high-voltage lithium metal batteries with excellent cycle life

The most attractive approach for maximizing the energy density of rechargeable lithium batteries is to combine a lithium metal anode with a high-voltage cathode. However, the dendritic formation of lithium at the anode and the highly oxidizing conditions that cause electrolyte decomposition at the cathode have hindered the practical development of lithium metal batteries (LMBs). In this study, we report a dual-type gel polymer electrolyte (GPE) composed of an anolyte and a catholyte that can address the drawbacks of both the anode and cathode sides. The anolyte is a poly(ethylene oxide)-based composite solid polymer electrolyte that is chemically stable with lithium metal and has a high mechanical strength for suppressing lithium dendrite growth. A cross-linked gel polymer electrolyte with high lithium-ion conductivity and oxidative stability was used as the catholyte. The Li/LiCoO2 cell assembled with a dual-type GPE exhibited a high discharge capacity of 181.1 mAh g−1 (areal capacity: 3.15 mAh cm−2) in the voltage range of 3.0–4.5 V and excellent cycle life, with a capacity retention of 74 % after 700 cycles at 25 °C and 0.5 C rate. Our study proposes a promising electrolyte system for LMBs with high energy density and good cycle life.

Cross-Linked Gel Polymer Electrolyte Based on Multiple Epoxy Groups Enabling Conductivity and High Performance of Li-Ion Batteries

The low ionic conductivity and unstable interface of electrolytes/electrodes are the key issues hindering the application progress of lithium-ion batteries (LiBs). In this work, a cross-linked gel polymer electrolyte (C-GPE) based on epoxidized soybean oil (ESO) was synthesized by in situ thermal polymerization using lithium bis(fluorosulfonyl)imide (LiFSI) as an initiator. Ethylene carbonate/diethylene carbonate (EC/DEC) was beneficial for the distribution of the as-prepared C-GPE on the anode surface and the dissociation ability of LiFSI. The resulting C-GPE-2 exhibited a wide electrochemical window (of up to 5.19 V vs. Li+/Li), an ionic conductivity (σ) of 0.23 × 10-3 S/cm at 30 °C, a super-low glass transition temperature (Tg), and good interfacial stability between the electrodes and electrolyte. The battery performance of the as-prepared C-GPE-2 based on a graphite/LiFePO4 cell showed a high specific capacity of ca. 161.3 mAh/g (an initial Coulombic efficiency (CE) of ca. 98.4%) with a capacity retention rate of ca. 98.5% after 50 cycles at 0.1 C and an average CE of about ca. 98.04% at an operating voltage range of 2.0~4.2 V. This work provides a reference for designing cross-linking gel polymer electrolytes with high ionic conductivity, facilitating the practical application of high-performance LiBs.

Single-Ion Gel Polymer Electrolyte based on In-Situ UV Irradiation Cross-Linked Polyimide Complexed with PEO for Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) have become the research focus of energy storage products. Due to the combination of Li+ and the Lewis basic sites of polymer chains, anions move more than five times faster, which do not participate in the electrode reaction during the discharge cycles, leading to concentration polarization, voltage losses, and high internal resistance. To solve this phenomenon, in this work, a polymer network structure of single-ion polymer electrolyte-based polyimide (DPI-SIGPE) with plasticizer ethylene carbonate (EC)/dimethyl carbonate (DMC) is formed by in-situ cross-linking double bond polyimide, 4-styrene sulfonyl (benzenesulfonyl) imide, and cross-linking agent pentaerythritol tetra(2-thiol acetate) under UV irradiation. By incorporating the anion as a part of the polymer chain, DPI-SIGPE exhibits high lithium-ion conductivity of 2.7 × 10-4 S cm-1 at 30 °C and transference number of 0.87. Typical lithium stripping/plating cycling of 900h demonstrates uniform lithium deposition impacted by DPI-SIGPE. Meanwhile, it has good dimensional thermal stability with no obvious shrinkage at 200 °C for 0.5h and wide electrochemical window of 4.6V. Thus, the polyimide-based cross-linked single-ion gel polymer electrolyte has the promising potential for application in LIBs.

In situ 3D crosslinked gel polymer electrolyte for ultra-long cycling, high-voltage, and high-safety lithium metal batteries

In situ 3D crosslinked gel polymer electrolyte for ultra-long cycling, high-voltage, and high-safety lithium metal batteries

A UV cross-linked gel polymer electrolyte enabling high-rate and high voltage window for quasi-solid-state supercapacitors

Serving as a promising alternative to liquid electrolyte in the application of portable and wearable devices, gel polymer electrolytes (GPEs) are expected to obtain more preferable properties rather than just be satisfied with the merits of high safety and deformability. Here, an easy-operated method is employed to fabricate cross-linked composite polymer membranes used for GPEs assisted by UV irradiation, in which N-doped carbon quantum dots (N-CQDs) and TiO2 are introduced as photocatalysts and additives to improve the performances of GPEs. Specifically, N-CQDs participate as a cross-linker to construct the inner porous structure, and TiO2 nanoparticles serve as a stabilizer to improve the electrochemical stability of GPEs under high voltage (3.5 V). The excellent thermal and mechanical stability of the membrane fabricated in this work guarantee the safety of the supercapacitors (SCs). This GPE based SC not only exhibits prominent rate performance (105% capacitance retention at the current density of 40 A g−1) and cyclic stability (85% at 1 A g−1 under 3.5 V after 20,000 cycles), but also displays remarkable energy density (42.88 Wh kg−1) with high power density (19.3 kW kg−1). Moreover, the superior rate and cycling performances of the as-prepared GPE based flexible SCs under flat and bending state confirm the feasibility of its application in flexible energy storage devices.

Stable Cycling of Room‐Temperature Sodium‐Sulfur Batteries Based on an In Situ Crosslinked Gel Polymer Electrolyte

AbstractHigh‐temperature sodium‐sulfur battery (HT Na–S) technology has attracted substantial interest in the stationary energy storage sector due to its low cost and high energy density. However, the currently used solid electrolyte (ß‐alumina) is expensive and can only be operated at high temperatures, which compromises safety. On the other hand, liquid electrolytes in room temperature sodium‐sulfur batteries (RT Na–S) are susceptible to dendrite formation and polysulfide shuttle. Consequently, an electrolyte with both solid (shuttle blocking) and liquid (ionic conductivity) properties to overcome the above‐mentioned issues is highly desired. Herein, a high‐performance quasi‐solid state crosslinked gel polymer electrolyte (GPE) prepared in situ using pentaerythritol triacrylate (PETA) exhibiting high ionic conductivity of 2.33 mS cm−1 at 25 °C is presented. The GPE‐based electrolyte shows high stability resulting in a high discharge capacity of >600 mAh gs−1 after 2500 cycles with an average Coulombic efficiency of 99.91%. Density functional theory calculations reveal a weak interaction between the Na+ ions and the oxygen molecules of the PETA moiety, which leads to a facile cation movement. The crosslinked polymer network is tightly connected to the cathode and can confine sulfides, thereby facilitating the conversion process.

Tough and redox-mediated alkaline gel polymer electrolyte membrane for flexible supercapacitor with high energy density and low temperature resistance

To meet the practical application requirements of the flexible supercapacitors, the improvements of the toughness and energy density attract more and more attention. Herein, a physically cross-linked double network alkaline gel polymer electrolyte (AGPE) membrane based on PVA and kappa-carrageenan is developed. In this AGPE membrane, KOH plays a dual role including carrier donator and ion cross-linker, which makes the AGPE membrane show the unique improvement of ionic conductivity (0.31 S/cm) and mechanical properties (tensile strength of 1.62 MPa and tensile elongation of 670%) at the same time. In order to improve energy density, the redox-active mediator p-phenylene diamine has been introduced in the AGPE membrane, endowing the fabricated supercapacitor with high electrode specific capacitance (741 F/g) and energy density (18.3 Wh/kg) with a maximum power density of 800 W/kg. Meanwhile, the supercapacitor can exhibit great flexibility and toughness, and maintain stable capacitance performance under bending and stretching state. Moreover, the supercapacitor shows an excellent low temperature resistance and it is able to maintain 82% of its room-temperature capacitance even at -40 °C. This investigation offers a strategy to prepare gel polymer electrolyte membrane with high adaptive ability of deformation and low temperature, which has potential application in various flexible, portable and wearable electronics. • Dual role KOH can improve conductivity and mechanical properties simultaneously. • PPD can signally increase the capacitance and energy density of EDLC supercapacitor. • Supercapacitor shows ideal electrochemical properties under deformation and coldness.

Facile In Situ Chemical Cross-Linking Gel Polymer Electrolyte, which Confines the Shuttle Effect with High Ionic Conductivity and Li-Ion Transference Number for Quasi-Solid-State Lithium-Sulfur Battery.

As a secondary Li-ion battery with high energy density, lithium-sulfur (Li-S) batteries possess high potential development prospects. One of the important ingredients to improve the safety and energy density in Li-S batteries is the solid-state electrolyte. However, the poor ionic conductivity largely limits its application for the commercial market. At present, the gel electrolyte prepared by combining the electrolyte or ionic liquid with the all-solid electrolyte is an effective method to solve the low ion conductivity of the solid electrolyte. We present a cross-linked gel polymer electrolyte with fluoroethylene carbonate (FEC) as a solid electrolyte interface (SEI) film formed for Li-S quasi-solid-state batteries, which can be simply synthesized without initiators. This gel polymer electrolyte with FEC as an additive (GPE@FEC) possesses high ionic conductivity (0.830 × 10-3 S/cm at 25 °C and 1.577 × 10-3 S/cm at 85 °C) and extremely high Li-ion transference number (tLi+ = 0.674). In addition, the strong ability toward anchoring polysulfides resulting in the high electrochemical performance of Li-S batteries was confirmed in GPE@FEC by the diffusion experiment, X-ray photoelectron spectroscopy analysis (XPS), and scanning electron microscopy (SEM) mapping of the S element. Such a high ion conductivity (IC) gel polymer electrolyte enables a competitive specific capacity of 940 mAh/g at 0.2C and supreme cycling performance for 180 cycles at 0.5C, which is far beyond that of conventional poly(ethylene oxide)-based quasi-solid-state Li-S batteries.

Cross-Linked Composite Gel Polymer Electrolyte Based on an H-Shaped Poly(ethylene oxide)-Poly(propylene oxide) Tetrablock Copolymer with SiO2 Nanoparticles for Solid-State Supercapacitor Applications.

Achieving high ionic conductivity, wide voltage window, and good mechanical strength in a single material remains a key challenge for polymer-based electrolytes for use in solid-state supercapacitors (SCs). Herein, we report cross-linked composite gel polymer electrolytes (CGPEs) based on multi-cross-linkable H-shaped poly(ethylene oxide)–poly(propylene oxide) (PEO-PPO) tetrablock copolymer precursors, SiO2 nanoparticles, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, an ionic liquid (IL). Self-standing CGPE membranes with a high IL content were prepared using in situ cross-linking reactions between the silane groups present in the precursor and the SiO2 surface. The incorporation of an optimal amount of SiO2 increased the cross-linking density of the resulting CGPE while reducing polymer-chain ordering and, consequently, increasing both ionic conductivity and mechanical strength. As a result, the CGPE with 0.1 wt % SiO2 exhibited a high ionic conductivity (2.22 × 10–3 S cm–1 at 25 °C), good tensile strength (453 kPa), and high thermal stability up to 330 °C. Finally, an all-solid-state SC assembled with the prepared CGPE showed a high operating voltage (3 V), a large specific capacitance (103.9 F g–1 at 1 A g–1), and excellent durability (94% capacitance retention over 10,000 charge/discharge cycles), which highlights its strong potential as a solid-state electrolyte for SCs.

Novel Cross-Linked Gel Polymer Electrolyte (GPE) with Long-Term Cycle Life for Li-Metal Batteries

Lithium metal batteries (LMBs) are considered among the most promising energy storage technologies due to their very high energy density and lightweight. While liquid electrolytes (LEs) offer high ionic conductivities (10−3−10−2 S cm−1) and low interfacial resistance with electrodes, yet the risks of leakage and combustion of organic solvents, lithium (Li) dendrite formation, thermal runaway, and environmental concerns regarding using organic solvents hinder their full potential applications. Li dendrites are mainly induced by nonuniform distribution of charge or ions and formation of a fragile, unstable solid electrolyte interphase (SEI) layer on Li metal anode during electrochemical Li deposition. The dendritic morphology of electrochemically deposited Li results in inefficient lithiation/delithiation and the formation of inactive or dead Li and constant degradation of organic solvents during Li plating/stripping, leading to capacity decade and decline in cycle life. Furthermore, lithium dendrites can pose a safety issue by penetrating through a porous or mechanically soft separator and making a short-circuit. High voltage instability of conventional electrolytes is another issue restricting application of high potential cathodes to enhance the energy density of LMBs. Gel polymer electrolytes (GPEs) are considered a promising alternative for LEs because of their high ionic conductivities (10−3−10−2 S cm−1), prevention of liquid leakage, low flammability, chemical and electrochemical stability, high flexibility for portable and wearable electronics, suppression of dendrite formation, and ample chemistry and design [1-4].In this work, we have developed a novel, highly efficient PEO-based GPE by a simple, facile chemical method and using UV light-induced cross-linking. Cross-linking is essential to retain the structure of the polymer electrolyte and it is also shown to suppress Li dendrite growth by offering a high stiffness and rigidity (high shear modulus) toward Li dendrites. The designed GPE owns a very high ionic conductivity similar to commercial LEs, electrochemical stability up to 5 V, long-term cycle life and stability. While Li|Li symmetric cells made with 1 M LiPF6 in EC/DEC and 1 M LiTFSI in DOL/DME LEs showed an increase in overpotential during cycling (mainly due to the formation of dead Li and evolution of SEI) followed by a short-circuit (probably due to penetration of Li dendrites through Celgard separator), Li|Li cells made with GPE exhibit a long-term stability with a low voltage polarization of less than 0.1 V at a high current density of 0.5 mAh cm−2 for 500 cycles. Furthermore, Li|LFP full cells made with GPE display a long-term cycle life with discharge capacity of ~120 mAh g−1 at 0.5 C in ambient temperature with around 80% capacity retention after 500 cycles.In situ light microscopy which is a simple, versatile technique to study the nucleation and growth of Li particles during electrochemical platting/stripping was also used to further illustrate uniform deposition of Li by the developed GPEs. Hence, we have also performed light microscopy analysis to investigate Li deposition in Li|Li cells made of LEs and GPEs during electrochemical deposition process. It was observed that unlike LEs made of 1 M LiPF6 in EC/DEC and 1 M LiTFSI in DOL/DME which results in non-uniform, dendritic growth of Li, a uniform and non-dendritic deposition of Li was observed in case of GPE, which can be due to uniform regulation of Li through complexation with oxygen atoms of the PEO-based GPE.

Chemically Cross-Linked Gel Polymer Electrolytes for Highly Safe Lithium-Ion Batteries with Good Cycling Stability

Liquid electrolytes used in lithium-ion batteries have many drawbacks such as high flammability, high reactivity toward electrode materials and solvent leakage. To overcome these problems, most recent research has focused on synthesis and characterization of highly conductive gel polymer electrolytes containing large number of organic solvents in the polymer matrix. However, there are still many hurdles to overcome before they can be applied to lithium-ion batteries. Since a large amount of organic solvent is required to achieve high ionic conductivity, battery safety is not significantly enhanced. In this study, we synthesized chemically cross-linked gel polymer electrolyte containing small amounts of organic solvents. The chemically cross-linked gel polymer electrolyte enhanced thermal safety of battery due to the effective trapping ability of organic solvents in the polymer matrix. The resulting gel polymer electrolyte was applied to lithium-ion cells composed of graphite anode and LiNi0.6Co0.2Mn0.2O2 cathode. We investigated their electrochemical performance, thermal stability, and solvent leakage behavior.

Safety Enhanced Quasi-Solid-State Electrolyte Based on Thiol-Ene Click Chemistry for Rechargeable Lithium Ion Batteries

Lithium-ion batteries(LIBs) are considered the most effective power source for various applications such as mobile electronics, electric vehicles and energy storage systems due to their favorable energy density and long cycle life. However, liquid electrolyte currently used in LIBs has critical drawbacks such as flammability and leakage problem. To make a breakthrough of these problems, intensive efforts have been devoted to replace liquid electrolyte to safer electrolytes. Among various electrolyte systems, the chemically cross-linked gel polymer electrolytes can enhance the thermal safety of LIBs by encapsulating organic solvent in the polymer matrix. However, they usually contain a large amount of organic solvents to achieve high ionic conductivity, and side reactions may occur during the cross-linking reaction. However, they usually contain a large amount of organic solvents to achieve high ionic conductivity, and side reactions may occur during the cross-linking reaction, causing cell degradation due to impurities affecting electrochemical performance. In this work, we report the synthesis and electrochemical characteristics of quasi-solid-state electrolytes using thiol-ene click chemistry. During cell assembly, the cathode was coated with electrolyte precursor and thermally cured using thiol-ene click chemistry, since the click reaction can avoid side reactions and drive fast cross-linking under mild reaction conditions. The obtained cathode with quasi-solid-state electrolyte was applied to the lithium-ion cell composed of graphite anode and LiNi0.6Co0.2Mn0.2O2 cathode, and their electrochemical performance was investigated. Our result demonstrates that the quasi-solid-state polymer electrolyte can be a promising electrolyte for achieving high performance and enhancing battery safety.