Probing Lithium Metals in Batteries by Advanced Characterization and Analysis Tools

Abstract Lithium metal batteries (LMBs) are one of the most promising next‐generation batteries in achieving the high energy density because of their low reduction potential and large theoretical capacity. However, since the birth of the first rechargeable lithium batteries, the uncontrolled lithium growth and the accompanying side‐reactions have seriously hampered the development of LMBs. Decades of research efforts have extensively studied the mechanisms governing these issues; however, the practical adoption of lithium metal in batteries is still yet to come. Recent advancements of the characterization tools offer unprecedentedly detailed views of the behavior of lithium metals in the electrochemical cells, which have been considered challenging due to the intrinsic instability of lithium metal. This new capability elucidates the stripping and deposition nature of lithium metal more closely, thus revealing what had been overlooked or remained unseen. Herein, recent advances in characterization and analysis tools for studies of LMBs are summarized, and what new findings and insights have been obtained in the understanding of LMBs are discussed. It is believed that this report will aid in addressing the opportunities and remaining challenges in the research of lithium metal by giving a comprehensive perspective on the current advanced suits of characterization tools, therefore expediting the development of practical LMBs.