Design of Stretchable and Self-Healing Gel Electrolytes via Fully Zwitterionic Polymer Networks in Solvate Ionic Liquids for Li-Based Batteries
Design of Stretchable and Self-Healing Gel Electrolytes via Fully Zwitterionic Polymer Networks in Solvate Ionic Liquids for Li-Based Batteries
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DOI：
10.1021/acs.chemmater.9b00172
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发表时间：
2019-04-23
影响因子：
8.6
通讯作者：
Panzer, Matthew J.
中科院分区：
文献类型：
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作者：
D'Angelo, Anthony J.;Panzer, Matthew J.
溶剂型离子液体是一类由络合锂离子和弱碱性阴离子组成的离子密集型电解质，具有许多理想的锂基电化学储能性能。在本研究中，两种两性离子单体2-甲基丙烯酰氧乙基磷酰胆碱(MPC)和磺基甜菜碱乙烯基咪唑(SBVI)在溶剂离子液体[Li(G4)][TFSI]中紫外光引发自由基(Co)聚合，合成了一系列全两性离子(f-Zi)聚合物支架支撑的溶剂型离子凝胶。系统地改变f-Zi聚合物网络中MPC：SBVI的摩尔比，使人们能够广泛地调节聚(MPC-co-SBVI)支撑的溶剂型离子凝胶复合材料的力学性能。当聚合物含量为20%时，凝胶压缩弹性模量值为2个数量级，范围为23~7.3 Mpa，而室温离子电导率基本保持不变(在0.48~0.70ms cm(-1)之间)。富含MPC的共聚物配方导致溶剂化离子凝胶表现出显著的塑性变形，在失效前超过200%的拉伸应变，锂离子迁移数高达0.60，与整洁的溶剂化离子液体电解质相比，锂离子迁移数增加了5倍。20mol%聚(MPC-co-SBVI)负载的溶剂型离子凝胶的摩尔比为3：1MPC：SBVI，成功地实现了锂离子电池样机以C/2的速率恒流循环100次，证明了这些更安全的凝胶电解质用于锂基储能设备的可行性。
An emerging class of ion-dense electrolytes consisting of complexed lithium cations and weakly basic anions, known as solvate ionic liquids, possess many desirable attributes for lithium-based electrochemical energy storage. In this study, a series of fully zwitterionic (f-ZI) polymer scaffold-supported solvate ionogels are synthesized via UV-initiated free-radical (co)polymerization of two zwitterionic monomers, 2-methacryloyloxyethyl phosphorylcholine (MPC) and sulfobetaine vinylimidazole (SBVI), in situ within the solvate ionic liquid [Li(G4)][TFSI], which is prepared from an equimolar mixture of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and tetraglyme (G4). Systematically varying the MPC:SBVI molar ratio within the f-ZI polymer network enables one to widely tune the mechanical properties of the poly(MPC-co-SBVI)-supported solvate ionogel composites. For a fixed polymer content of 20 mol %, gel compressive elastic modulus values are observed to span 2 orders of magnitude, from 23 kPa to 7.3 MPa, while the room temperature ionic conductivity values remain fairly unchanged (between 0.48 and 0.70 mS cm(-1)). MPC-rich copolymer formulations lead to solvate ionogels that exhibit substantial plastic deformation, exceeding 200% tensile strain prior to failure, and Li-ion transference numbers as high as 0.60, which represents a 5-fold increase compared to the neat solvate ionic liquid electrolyte. A 20 mol % poly(MPC-co-SBVI)supported solvate ionogel having a 3:1 MPC:SBVI molar ratio successfully enables the galvanostatic cycling of a lithium-ion battery prototype for 100 cycles at a rate of C/2, demonstrating the viability of these safer gel electrolytes for lithium-based energy storage devices.