Solid polymer electrolytes (SPEs) that offer superior safety, mechanical strength and flexibility are crucial for advancing next-generation sodium-ion batteries (SIBs). Conventional SPEs often display temperature sensitivity, leading to relatively low ionic conductivity at room temperature (RT). Herein, lignin-based SPEs (LG-SPEs) are created by solvation and desolvation of lignin and sodium bis(fluorosulfonyl)imide (NaFSI). Theoretical calculations reveal that lignin (containing rich functional groups) and FSI− molecules facilitate the movement of Na-ions within the electrolyte by minimizing steric hindrance and offering migration sites. Consequently, LG-SPEs demonstrate an enhanced ionic conductivity of 3.4 × 10−4 S cm−1 at RT, with a Na-ion transfer number as high as 0.53. The assembled all-solid-state SIB comprising Na3V2(PO4)3/LG-SPE/NaTi2(PO4)3 exhibits excellent electrochemical performance at RT, achieving a specific capacity of 95 mA h g−1 and retaining 82 % of its capacity after 200 cycles at 0.1 C. This work presents an environmentally friendly and straightforward methodology for developing high-performance SPEs at RT, while also opening up new avenues for the valorization of lignin.

中文翻译：

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用于室温下全固态钠离子电池的大分子木质素天然超离子聚合物电解质


具有卓越安全性、机械强度和柔韧性的固体聚合物电解质 （SPE） 对于推进下一代钠离子电池 （SIB） 至关重要。常规 SPE 通常表现出温度敏感性，导致室温 （RT） 下的离子电导率相对较低。在本文中，基于木质素的 SPE （LG-SPE） 是通过木质素和双（氟磺酰基）酰亚胺钠 （NaFSI） 的溶剂化和脱溶剂化而生成的。理论计算表明，木质素（包含丰富的官能团）和 FSI-分子通过最大限度地减少空间位阻和提供迁移位点来促进 Na 离子在电解质内的移动。因此，LG-SPE 在 RT 下表现出 3.4 × 10−4 S cm−1 的增强离子电导率，Na 离子转移数高达 0.53。由 Na3V2（PO4）3/LG-SPE/NaTi2（PO4）3 组成的组装全固态 SIB 在 RT 下表现出优异的电化学性能，达到 95 mA h g-1 的比容量，并在 0.1 C 下循环 200 次后仍保留 82% 的容量。这项工作提出了一种在 RT 下开发高性能 SPE 的环保且简单的方法，同时也为木质素的价值化开辟了新的途径。