Durable lithium-ion insertion/extraction and migration behavior of LiF-encapsulated cobalt-free lithium-rich manganese-based layered oxide cathode.

Lithium-rich manganese-based cathode has made a subject of intense scrutiny for scientists and application researchers due to their exceptional thermal stability, high specific capacity, high operating voltage, and cost-effectiveness. However, the inclusion of cobalt, as a crucial component in lithium-rich manganese-based cathode materials, has become a cause for concern due to its limited availability and non-renewable nature, which eventually limits the growth of the battery industry and increase costs. Considering the poor stability of cobalt-free cathode, this work proposes a coating strategy of LiF through a simple high-temperature melting method. Directly coating LiF on LiNiMnO surface is found to be an effective way to protect the cathode material, decrease metal solubility, and inhibit irreversible phase transition processes, thus leading to an improved electrochemical performance. As a result, the battery employing LiF coated LiNiMnO cathode can be stabilized over 280 cycles and maintain a capacity of 110 mAh g at 1C. What's more, the mechanisms of ion insertion/extraction behavior and ion migration process are also studied systematically. This study will open the avenue to develop a high-energy battery system with cobalt-free cathode.