Abstract：
Low ionic conductivity and poor interface stability of poly(ethylene oxide) (PEO) restrict the practical application as polymeric electrolyte films to prepare solid-state lithium (Li) metal batteries. In this work, biomass-based carboxymethyl chitosan (CMCS) is designed and developed as organic fillers into PEO matrix to form composite electrolytes (PEO@CMCS). Carboxymethyl groups of CMCS fillers can promote the decomposition of Lithium bis(trifluoromethane sulfonimide) (LiTFSI) to generate more lithium fluoride (LiF) at CMCS/PEO interface, which not only forms ionic conductive network to promote the rapid transfer of Li+ but also effectively enhances the interface stability between polymeric electrolyte and Li metal. The enrichment of carboxyl, hydroxyl, and amidogen functional groups within CMCS fillers can form hydrogen bonds with ethylene oxide (EO) chains to improve the tensile properties of PEO-based electrolyte. In addition, the high hardness of CMCS additives can also strengthen mechanical properties of PEO-based electrolyte to resist penetration of Li dendrites. LiLi symmetric batteries can achieve stable cycle for 2500 h and lithium iron phosphate full batteries can maintain 135.5 mAh g-1 after 400 cycles. This work provides a strategy for the enhancement of ion conductivity and interface stability of PEO-based electrolyte, as well as realizes the resource utilization of biomass-based CMCS.
摘要：
聚（环氧乙烷）（PEO）的低离子电导率和差的界面稳定性限制了其作为聚合物电解质膜制备固态锂（Li）金属电池的实际应用。在这项工作中,基于生物质的羧甲基壳聚糖（CMCS）被设计和开发为PEO基质中的有机填料，以形成复合电解质（PEO@CMCS）。CMCS填料的羧甲基可以促进双(三氟甲烷磺酰亚胺)锂(LiTFSI)的分解，在CMCS/PEO界面生成更多的氟化锂(LiF)，不仅形成离子导电网络促进Li+的快速转移,而且有效增强了聚合物电解质与Li金属之间的界面稳定性。羧基的富集，羟基，CMCS填料内的酰胺基官能团可以与环氧乙烷(EO)链形成氢键以改善基于PEO的电解质的拉伸性能。此外,高硬度的CMCS添加剂还可以增强PEO基电解质的机械性能，以抵抗Li枝晶的渗透。LiLi对称电池可实现2500h的稳定循环，磷酸铁锂全电池在400次循环后可保持135.5mAhg-1。这项工作为增强PEO基电解质的离子电导率和界面稳定性提供了一种策略，以及实现生物质基CMCS的资源化利用。
