Sun Siyu, Zeng Huipeng, Cui Baichuan, Zhi Mingjia, Zheng Jing, Hong Zhanglian, Xu Jijian
State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China.
Department of Chemistry, City University of Hong Kong, Hong Kong 999077, P. R. China.
ACS Appl Mater Interfaces. 2025 Oct 1;17(39):54623-54632. doi: 10.1021/acsami.5c07417. Epub 2025 Sep 18.
Lithium metal batteries (LMBs) face severe interfacial degradation due to uncontrolled lithium dendrite growth and electrolyte decomposition. Conventional electrolytes fail to concurrently stabilize lithium metal anodes and high-voltage cathodes owing to competing parasitic reactions. Here, we report a softly solvating electrolyte composed of 1,3-dioxane (1,3-DX) and dual salts─lithium bis(fluorosulfonyl)imide/lithium hexafluorophosphate (LiFSI/LiPF)─that leverages anion-complementary coordination to decouple interfacial requirements. The solvent's steric hindrance softens Li-solvent interactions, enabling FSI and PF to spatially separate their interfacial functions: FSI drives LiF-rich solid-electrolyte interphase (SEI) formation on Li metal, while PF constructs a thin (<10 nm) cathode-electrolyte interphase (CEI) on LiNiCoMnO (NCM523) cathodes. Raman and O NMR spectra confirm suppressed solvent coordination and anion-aggregate dominance. Li||NCM523 cells utilizing this electrolyte achieve over 80% capacity retention after 100 cycles at 4.3 V, with a high average Coulombic efficiency (CE) above 99.0%. Cross-sectional scanning electron microscopy/transmission electron microscopy (SEM/TEM) reveals crack-free cathodes and robust, homogeneous SEI and CEI layers. Remarkably, the Li||NCM523 cells maintain 36.9% capacity retention of their room-temperature performance (54.7 vs 148.3 mAh g) at 0.2 C and -30 °C, highlighting the electrolyte's low-temperature compatibility. This work establishes an anion-synergistic design strategy to reconcile bulk ion transport with dual electrodes.
锂金属电池（LMBs）由于锂枝晶生长失控和电解质分解而面临严重的界面降解问题。传统电解质由于存在竞争性寄生反应，无法同时稳定锂金属负极和高压正极。在此，我们报道了一种由1,3 - 二氧六环（1,3 - DX）和双盐——双（氟磺酰）亚胺锂/六氟磷酸锂（LiFSI/LiPF）组成的软溶剂化电解质，该电解质利用阴离子互补配位来解耦界面需求。溶剂的空间位阻软化了锂 - 溶剂相互作用，使FSI和PF能够在空间上分离它们的界面功能：FSI促使在锂金属上形成富含LiF的固体电解质界面（SEI），而PF在LiNiCoMnO（NCM523）正极上构建薄（<10 nm）的正极 - 电解质界面（CEI）。拉曼光谱和O核磁共振光谱证实了溶剂配位受到抑制以及阴离子聚集体占主导地位。使用这种电解质的Li||NCM523电池在4.3 V下循环100次后容量保持率超过80%，平均库仑效率（CE）高于99.0%。横截面扫描电子显微镜/透射电子显微镜（SEM/TEM）显示正极无裂纹，SEI和CEI层坚固且均匀。值得注意的是，Li||NCM523电池在0.2 C和 - 30°C下保持其室温性能（54.7对148.3 mAh g）的36.9%容量保持率，突出了该电解质的低温兼容性。这项工作建立了一种阴离子协同设计策略，以协调双电极的体相离子传输。
