Gel polymer electrolyte (GPE) is one of the promising candidates to overcome the defects of liquid and solid electrolyte for lithium metal batteries (LMBs). The obstacle for the practical application of GPEs lies in achieving a balance between ion transport, mechanical properties and interface stability. In this work, a star shaped polymer matrix polyhedral oligomeric silsesquioxane-polymethyl methacrylate (POSS-PMMA) is successfully synthesized with POSS as the core via atom transfer radical polymerization (ATRP) method. 1-ethyl-3-methylimidazole bis(trifluoromethanesulfon)imide ([EMIM][TFSI]) and bistrifluoromethanesulfonimide lithium salt (LiTFSI) are blended with the matrix to increase ionic conductivity. Attributed to the star structure and the lithium ion migration channel provided by POSS, the synthesized GPE possesses excellent balanced mechanical and electrochemical properties. To further stabilize the Li/GPE interface, a polymer and plastic crystalline electrolyte (PPCE) is coated as interface modification layer on both sides of GPE. Benefitting from the design, the synthesized GPE reaches a highly stable Li striping/plating cycling for 1000 h at 0.1 mA cm⁻² with ionic conductivity of 3.5×10⁻⁴ S cm⁻¹, Li⁺ transference number of 0.35, and electrochemical stability window of 4.9 V. Furthermore, the Li||POSS-PMMA-PPCE||LiFePO₄ (LFP) full cell shows a high capacity retention of 99.5% after 100 cycles at 0.2 C under room temperature (RT), and the high voltage Li||POSS-PMMA-PPCE||LiNi_1-x-yMnxCo_yO₂ (NCM811) cell shows a high capacity retention of 88.3% after 50 cycles at 0.1 C under RT. This work opens up a new frontier to stabilize the Li/GPE interface and enables safe operation of room temperature lithium metal batteries.

中文翻译：

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一种用于锂金属电池的电化学和机械性能平衡的明星聚合物 POSS-PMMA 基凝胶电解质


凝胶聚合物电解质 （GPE） 是克服锂金属电池 （LMB） 中液体和固体电解质缺陷的有前途的候选者之一。GPE 实际应用的障碍在于实现离子传输、机械性能和界面稳定性之间的平衡。本工作通过原子转移自由基聚合 （ATRP） 方法成功合成了以 POSS 为核心的星形聚合物基多面体寡聚体倍半硅氧烷-聚甲基丙烯酸甲酯 （POSS-PMMA）。将 1-乙基-3-甲基咪唑双（三氟甲磺酰亚胺）酰亚胺 （[EMIM][TFSI]） 和双三氟甲磺酰亚胺锂盐 （LiTFSI） 与基质混合，以提高离子电导率。得益于 POSS 提供的星形结构和锂离子迁移通道，合成的 GPE 具有优异的平衡机械和电化学性能。为了进一步稳定 Li/GPE 界面，在 GPE 的两侧涂覆了聚合物和塑料结晶电解质 （PPCE） 作为界面修饰层。得益于该设计，合成的 GPE 在 0.1 mA ^cm-2 下达到了高度稳定的 Li 条带/电镀循环 1000 小时，离子电导率为 3.5×^10-4 S ^cm-1，Li+ 转移数为 0.35，电化学稳定性窗口为 4.9 V。此外，Li||POSS-PMMA-PPCE||LiFePO₄ （LFP） 全电池在室温 （RT） 下在 0.2 C 下循环 100 次后显示出 99.5% 的高容量保持率，并且高压 Li||POSS-PMMA-PPCE||LiNi_1-x-yMnxCo_yO₂ （NCM811） 电池在 RT 下在 0.1 C 下循环 50 次后显示出 88.3% 的高容量保留率。 这项工作为稳定 Li/GPE 界面并实现室温锂金属电池的安全运行开辟了新的领域。