Decoupling of Mechanical Strength and Ionic Conductivity in Zwitterionic Elastomer Gel Electrolyte toward Safe Batteries
Decoupling of Mechanical Strength and Ionic Conductivity in Zwitterionic Elastomer Gel Electrolyte toward Safe Batteries
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两性离子弹性体凝胶电解质中机械强度和离子电导率的解耦以实现安全电池
DOI：
10.1021/acsami.1c01064
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发表时间：
2021
影响因子：
9.5
通讯作者：
Wu Peiyi
中科院分区：
文献类型：
--
作者：
Liu Yan;Hou Lei;Jiao Yucong;Wu Peiyi
准固态电解质由于其在安全性和电化学性能方面的优越性，是下一代电池有前途的选择之一。然而，准固态电解质的电解质溶胀率和机械性能之间的权衡显着影响电池性能。在此，我们设计了一种由疏油两性离子聚(3-(1-乙烯基-3-咪唑啉)-丙烷磺酸盐)和亲油弹性体聚(丙烯酸2-甲氧基乙酯)链段组成的不溶胀、溶剂适应性聚合物凝胶，以在不牺牲锂电池机械性能的情况下保持高电池性能。所设计的凝胶不仅可以吸收足够的电解质以获得1.78 mS cm-1的高离子电导率，而且由于其在酯电解质中的不溶胀特性，在长时间浸泡后也能实现优异的机械强度，90%应变下的压缩应力（σ0.9）达到5.8 MPa，以确保电池安全。此外，所制备的两性离子凝胶有利于电解质盐解离，进一步提高电池的离子电导率和迁移数。因此，凝胶电解质可以在3 mA cm-2的高电流密度下循环超过500 h，具有抑制枝晶的性能，并且当与LiFePO4作为正极组装时，电池在5 C的高电流密度下经过300次循环后表现出高达70 mAh g-1的可逆比容量。合理设计的亲溶剂/疏溶剂两性离子弹性体为设计不同溶剂的准固态电解质提供了指导，在柔性器件上具有广泛的应用。
Quasi-solid state electrolyte is one of the promising options for next generation batteries due to its superiority on safety and electrochemistry performance. However, the trade-off between the electrolyte swelling ratio and mechanical property of the quasi-solid state electrolyte significantly influences the battery performance. Herein, we design a nonswelling, solvent-adaptive polymer gel composed of oleophobic zwitterion poly(3-(1-vinyl-3-imidazolio)-propanesulfonate) and oleophilic elastomer poly(2-methoxyethyl acrylate) segments to retain high battery performance without sacrificing the mechanical property in lithium batteries. The as-designed gel can not only uptake enough electrolyte for a high ionic conductivity of 1.78 mS cm–1but also achieve excellent mechanical strength with compression stress at 90% strain (σ0.9) reaching 5.8 MPa after long time soaking for battery safety due to its nonswelling property in ester electrolyte. Moreover, the as-prepared zwitterionic gel is beneficial to electrolyte salt dissociation, which further enhances the ionic conductivity and transference number of batteries. Consequently, the gel electrolyte can cycle for more than 500 h under a high current density of 3 mA cm–2on dendrite inhibition performance, and when assembled with LiFePO4as a cathode, the battery demonstrates a reversible specific capacity as high as 70 mAh g–1under a high current density of 5 C after 300 cycles. The rational designed solvophilic/solvophobic zwitterionic elastomers provide a guidance for engineering quasi-solid state electrolytes of different solvents with broad applications on flexible devices.