Composite\nLithium Protective Layer Formed In Situ\nfor Stable Lithium Metal Batteries

Abstract

Lithium metal is considered as the\nideal anode for next-generation\nrechargeable batteries due to its highest theoretical specific capacity\nand lowest electrochemical potential. However, lithium dendrite growth\nduring lithium deposition could lead to a short circuit and even cause\nsevere safety issues. Here, we use solid-state electrolyte Li₃InCl₆ as an additive in nonaqueous electrolytes\nbecause of its high ionic conductivity (10^–3 to\n10^–4 S cm^–1) and good electrochemical\nstability. It is found that Li₃InCl₆ can in\nsitu react with metallic lithium to form a ternary composite solid\nelectrolyte interphase (SEI) consisting of a Li–In alloy, LiCl,\nand codeposited Li₃InCl₆. The composite SEI\ncan effectively suppress Li dendrite growth and thereby maintain stable\nlong-term cycling performance in lithium metal batteries. The protected\nlithium electrode exhibits stable cycling performance in a symmetric\nLi|Li battery for nearly 1000 h at a current density of 1 mA cm^–2. Besides, the full battery with a LiFePO₄ cathode and a metallic lithium anode delivers a stable capacity\nof 140.6 mA h g^–1 for 500 cycles with a capacity\nretention of 95%. The Li|S battery with Li₃InCl₆-added LiTFSI in 1,3-dioxolane/1,2-dimethoxyethane electrolyte also\nshows significant improvement in capacity retention at 0.5 C. This\nwork demonstrates an effective approach to design dendrite-free metal\nanodes.