Regulation Roles of p-Block Elements in Lithium Layered Oxide Cathodes: Recent Progress and Perspectives

Layered oxides derived from Li_xTM_yO₂ (TM: Ni, Co, Mn and etc.), based on the de/intercalation mechanism, have long served as the backbone of lithium-ion batteries (LIBs) for portable electronics, electric vehicles, and energy storage. However, the unstable structural evolution, sluggish diffusion kinetics, and detrimental interface parasitic reaction deteriorate their electrochemical performance. Due to p-block elements with unique electronic structures, the substitution in Li_xTM_yO₂ with p-block elements has become one of the mainstream practices. Therefore, clarifying the relationship among substitution, structure and performance is critical for rational design of high-performance LIBs. However, a systematic review focusing on regulation roles of p-block elements in Li_xTM_yO₂ cathodes is lacking. Seeking to systematically understand the interaction between p-block elements with the matrix of Li_xTM_yO₂ cathodes, herein, we firstly outline the structure and mechanisms of Li_xTM_yO₂ cathodes, then highlight the internal structural degradation and external interface instability. And the performance enhancement mechanisms are emphasized in detail. Secondly, according to the order of the main group, a comprehensive review on the progress of p-block element substitution in Li_xTM_yO₂ are provided. Finally, the challenges and future perspectives are figured out, which can shed light on the design guideline of Li_xTM_yO₂ cathodes in the future.