Research Progress in Lithium-Excess Disordered Rock-Salt Oxides Cathode

Abstract

The increasing demand for new energy sources has promoted the improvement of the energy storage capacity of lithium-ion batteries (LIBs) that urged the development of higher energy density cathode materials. The enhancement of the classical cathode in the last 30 years has reached a bottleneck, and then the discovery of the lithium-excess disordered materials has greatly expanded the research space of the cathode materials. Compared with the conventional layered oxides, the lithium-excess disordered rock-salt oxides (LEDRXs) with a more stable structure has higher extractable Li+ content, even though the inactive high-valent transition metals (TMs) were needed to compensate for the excess Li, which would reduce the total TM redox content. In addition, oxygen redox provides additional electron capacity for the materials, which also causes O loss and results in the subsequent poor cycle performance. Herein, a series of studies about LEDRXs and their targeted modification measures are summarized, including the prospect of the materials, in order to provide ideas for the design of high-performance LEDRXs. Finally, the new discoveries and outlook on future research directions of LEDRX cathode materials for LIBs with higher energy density are given.