註釋 Lithium (Li) metal-based rechargeable batteries hold significant promise to meet the ever-increasing demands for portable electronic devices, electric vehicles and grid-scale energy storage, making them the optimal alternatives for next-generation secondary batteries. Nevertheless, Li metal anodes currently suffer from major drawbacks, including safety concerns, capacity decay and lifespan degradation, which arise from uncontrollable dendrite growth, notorious side reactions and infinite volume variation, thereby limiting their current practical application. Numerous critical endeavors from different perspectives have been dedicated to developing highly stable Li metal anodes. Herein, a comprehensive overview of Li metal anodes regarding fundamental mechanisms, scientific challenges, characterization techniques, theoretical investigations and advanced strategies is systematically presented. First, the basic working principles of Li metal-based batteries are introduced. Specific attention is then paid to the fundamental understanding of and challenges facing Li metal anodes. Accordingly, advanced characterization approaches and theoretical computations are introduced to understand the fundamental mechanisms of dendrite growth and parasitic reactions. Recent key progress in Li anode protection is then comprehensively summarized and categorized to generate an overview of the respective superiorities and limitations of the various strategies. Furthermore, this review concludes the remaining obstacles and potential research directions for inspiring the innovation of Li metal anodes and endeavors to accomplish the practical application of next-generation Li-based batteries. 