Sodium metal batteries (SMBs) with gel polymer electrolytes (GPEs) are considered promising candidates for high energy-density batteries due to their high theoretical capacity and cost effectiveness. However, the intrinsic flammability of GPE poses challenges for their widespread application. Inspired by the concept of the capsules, a triethyl phosphate (TEP)-based GPE with co-sustained-release effect has been designed. This structure features an insoluble ethoxylated trimethylopropane triacrylate (ETPTA) polymer matrix combined with carbonate co-solvents, effectively reducing the corrosion of TEP on sodium metal anodes while maintaining a continuous flame-retardant effect. In this distinctive structure, the abundant carbonyl group on ETPTA promotes the uniform migration of sodium ions, while the carbonate co-solvent facilitates the formation of a NaF-rich solid electrolyte interphase (SEI) layer, effectively suppressing the growth of sodium dendrite. Low content of TEP guide the preferential orientation of the (100) crystal plane of sodium anode, enhancing the long-term cycling stability. Na/GPE/Na cells can achieve stable cycling for over 1600 hours, and the NVP/GPE/Na full cells exhibit 86.6% capacity retention after 4000 cycles. Moreover, the engineered GPE enables the operation of a 4.5 V high-voltage cathode for 500 cycles. This strategy paves a new way for designing high-safety GPE tailored for high-performance SMBs.

中文翻译：

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不易燃凝胶聚合物电解质的共缓释策略可实现长寿命钠金属电池

采用凝胶聚合物电解质 （GPE） 的钠金属电池 （SMB） 因其高理论容量和成本效益而被认为是高能量密度电池的有前途的候选者。然而，GPE 固有的可燃性对其广泛应用提出了挑战。受胶囊概念的启发，设计了一种基于磷酸三乙酯 （TEP） 的 GPE，具有共缓释作用。这种结构的特点是不溶性乙氧基化三甲基丙烷三丙烯酸酯 （ETPTA） 聚合物基质与碳酸盐助溶剂相结合，有效减少了 TEP 对钠金属负极的腐蚀，同时保持了持续的阻燃效果。在这种独特的结构中，ETPTA 上丰富的羰基促进了钠离子的均匀迁移，而碳酸盐助溶剂促进了富含 NaF 的固体电解质界面 （SEI） 层的形成，有效抑制了钠枝晶的生长。低含量的 TEP 引导钠阳极 （100） 晶面的优先取向，增强长期循环稳定性。Na/GPE/Na 细胞可实现超过 1600 小时的稳定循环，NVP/GPE/Na 全细胞在 4000 次循环后表现出 86.6% 的容量保持率。此外，设计的 GPE 能够让 4.5 V 高压阴极运行 500 次循环。此策略为设计专为高性能 SMB 定制的高安全性 GPE 铺平了一条新道路。