Abstract
All-solid-state lithium metal batteries (ASSLMBs) represent a pivotal advancement in energy storage, merging high energy density with enhanced safety. Among various solid-state electrolytes, oxide solid-state electrolytes (OSSEs) are particularly promising due to their superior thermal and electrochemical stability. However, their practical viability is constrained by low ionic conductivity, poor interfacial contact, and complexities in fabrication. Rational doping has emerged as a critical strategy to overcome these barriers. Rather than simple compositional adjustment, doping acts as a multiscale regulator, simultaneously optimizing bulk transport, grain boundary resistance, and interfacial compatibility. Despite its potential, doping efficacy is highly system-dependent, often presenting trade-offs between conductivity and stability, necessitating mechanism-guided design over empirical screening. This review synthesizes recent advances in rational doping, emphasizing the correlation between dopant chemistry, crystal structure, and electrochemical performance. Additionally, we emphasize the integration of computational and data-driven approaches as transformative tools for accelerating material discovery and multi-objective optimization. By bridging mechanistic understanding with computational design, this work outlines a paradigm shift from trial-and-error experimentation to predictive, application-oriented development of oxide electrolytes for practical ASSLMBs.