Review-Recent advances & remaining challenges for lithium ion battery cathodes II. Lithium-Rich, xLi₂MnO₃·(1-x)LiNi_aCo_bMn_cO₂

Electrodes prepared from lithium-rich (Li-rich) xLi₂MnO₃·(1-x)LiNi_aCo_bMn_cO₂materials (a + b + c = 1) show extremely high discharge capacities, arising from excess Li⁺ present in their Li₂MnO₃ component, and the ability to reversibly store charge with O^2-anions. These electrodes suffer serious voltage and capacity fading however, due to the migration of transition metals to the Li-layer at advanced states of charging, partial structural layered-To-spinel transformation and other reasons. In this focus paper, the current understanding of the above materials is summarized, briefly concluding with attempts by our groups to mitigate the voltage and capacity fade of these electrodes.