A Porous Li–Al Alloy Anode toward High‐Performance Sulfide‐Based All‐Solid‐State Lithium Batteries

Abstract Compared to lithium (Li) anode, the alloy/Li‐alloy anodes show more compatible with sulfide solid electrolytes (SSEs), and are promising candidates for practical SSE‐based all‐solid‐state Li batteries (ASSLBs). In this work, a porous Li–Al alloy (LiAl‐p) anode is crafted using a straightforward mechanical pressing method. Various characterizations confirm the porous nature of such anode, as well as rich oxygen species on its surface. To the best knowledge, such LiAl‐p anode demonstrates the best room temperature cell performance in comparison with reported Li and alloy/Li‐alloy anodes in SSE‐based ASSLBs. For example, the LiAl‐p symmetric cells deliver a record critical current density of 6.0 mA cm⁻² and an ultralong cycling of 5000 h; the LiAl‐p|LiNi_0.8Co_0.1Mn_0.1O₂ full cells achieve a high areal capacity of 11.9 mAh cm⁻² and excellent durability of 1800 cycles. Further in situ and ex situ experiments reveal that the porous structure can accommodate volume changes of LiAl‐p and ensure its integrity during cycling; and moreover, a robust Li inorganics‐rich solid electrolyte interphase can be formed originated from the reaction between SSE and surface oxygen species of LiAl‐p. This study offers inspiration for designing high‐performance alloy anodes by focusing on designing special architecture to alleviate volume change and constructing stable interphase.