Polysulfide-mediated solid-state wetting for low-pressure all-solid-state lithium metal batteries

Abstract

The quest for practical all-solid-state lithium metal batteries (ASSLMBs) has focused on achieving reliable operation at room temperature and low stack pressure. However, attempts to lower this pressure have proved challenging due to interfacial instabilities and unwanted lithium (Li) dendritic growth. Here, we introduce a solid-state wetting approach of the Li metal anode by utilizing a polysulfide derived from α-lipoic acid (LA) and lithiophilic tin (Sn) seeds. The polymeric network constructs strong interfacial bridges between the Li metal and solid electrolyte, while simultaneously driving the depth-wise redistribution of the pulverized Sn seeds throughout the bulk Li metal, thereby achieving comprehensive solid-state wetting that extends across the anode structure. This architecture, by concurrently mitigating the interfacial and bulk instabilities in Li_0.97Mg_0.03 metal anodes, enables stable operation at room temperature and low stack pressure (2.5 MPa), along with exceptional capacity retention of 86.7 % over 160 cycles at 0.5C with a high areal capacity of 3.5 mAh cm⁻². This study establishes foundational guidelines for the design of Li metal anodes toward high-performance ASSLMBs under practical operating conditions.