LiMn2O4 as a cathode material: challenges and opportunities for lithium-ion batteries

Abstract

In the search for suitable cathodes for lithium-ion batteries (LIBs), cathode materials with high upper cut-off voltages are promising candidates. Further, charging to a higher voltage (>4.3 V) introduces various challenges and negatively impacts battery performance, including surface damage, unwanted reactions, and stress-induced cracking. These factors often cause rapid capacity loss and reduce battery cycle life. Among the various cathode materials, LiMn₂O₄ is considered a good option owing to its cost-effectiveness, environmental benefits, and better capacity. However, decreased stability limits its capacity to function effectively at higher voltages. The failure mechanisms of LiMn₂O₄ under high voltage stress are reviewed in this study, with particular attention paid to how voltage stress impacts the functionality of the material and other associated issues, such as phase changes, manganese dissolution, and side reactions, that worsen the material's condition using in situ/operando techniques. Numerous modification techniques have been emphasized to increase high-voltage stability to address these problems. These include surface coatings and doping with additional elements that protect the structure and minimize unintended reactions. This study also explores cutting-edge methods for enhancing electrode–electrolyte interactions, including solid-state electrolytes, concentration-gradient designs, and electrolyte additives. Thus, the present review offers insights into how LiMn₂O₄ can be tailored to satisfy high-voltage application requirements, eventually opening the door to more potent and long-lasting LIBs.