With the blooming of energy storage systems in e-mobility applications, the research activities of rechargeable lithium metal (Li°) batteries (LMBs) using solid-state electrolytes have been rekindled in recent years in light of stringent demands in terms of safety and energy density which are far beyond the capability of the contemporary lithium-ion batteries (LIBs). Lithium metal polymer (LMP) batteries utilizing solid polymer electrolytes (SPEs) are inherently safe and easy to process, thus becoming in the spotlights of solid-state lithium metal batteries (SSLMBs) technologies. However, the widely used electrolyte salts generally contain the trifluoromethyl (—CF₃) group which has very low chemical and biochemical degradability, despite its strong electron-withdrawing ability which is essential for the dissolution and transport of ions in SPEs. In this work, a trifluoromethyl-free anion, bis(difluoromethanesulfonyl)imide {[N(SO₂CF₂H)₂]⁻, DFSI⁻}, as an environmentally benign and interfacially favourable anion for high-performance SSLMB is reported. In contrast to the popular bis(trifluoromethanesulfonyl)imide anion {[N(SO₂CF₃)₂]⁻, TFSI⁻}, the DFSI-based salt shows more rapid chemical degradation and its SPEs possess higher Li-only conductivity, significantly enhanced stability against Li° electrode, and better cell performance of LMP batteries. The results conveyed in this work may inspire the design of better SPEs, thus enabling a wider practical deployment of SSLMBs.

随着电动汽车应用中能量存储系统的兴起，鉴于对安全性和能源的严格要求，近年来重新点燃了使用固态电解质的可充电锂金属（Li°）电池（LMB）的研究活动。密度远远超出了现代锂离子电池（LIB）的能力。利用固态聚合物电解质（SPE）的锂金属聚合物（LMP）电池本质上安全且易于加工，因此成为固态锂金属电池（SSLMBs）技术的关注焦点。然而，广泛使用的电解质盐通常包含三氟甲基（-CF ₃）具有极低的化学和生化降解性的基团，尽管它具有很强的吸电子能力，这对于SPE中离子的溶解和运输至关重要。在这项工作中，自由三氟甲基阴离子，双（二氟甲磺酰）亚胺{[N（SO ₂ CF ₂ 2H）₂ ] ^-，DFSI ^- }，作为用于高性能SSLMB环境友好并且界面有利阴离子报道。与此相反的流行的双（三氟甲烷磺酰）亚胺阴离子{[N（SO ₂ CF ₃）₂ ] ^-，TFSI ^-}，基于DFSI的盐显示出更快的化学降解，其SPE具有更高的纯锂电导率，对Li°电极的稳定性显着增强以及LMP电池的更好电池性能。这项工作中传达的结果可能会启发设计更好的SPE，从而实现SSLMB的更广泛的实际部署。