Layered lithium-rich transition-metal oxides (LRMs) have been considered as the most promising next-generation cathode materials for lithium-ion batteries. However, capacity fading, poor rate performance, and large voltage decays during cycles hinder their commercial application. Herein, a spinel membrane (SM) was first in situ constructed on the surface of the octahedral single crystal Li1.22Mn0.55Ni0.115Co0.115O2 (O-LRM) to form the O-LRM@SM composite with superior structural stability. The synergetic effects between the single crystal and spinel membrane are the origins of the enhancement of performance. On the one hand, the single crystal avoids the generation of inactive Li2MnO3-like phase domains, which is the main reason for capacity fading. On the other hand, the spinel membrane not only prevents the side reactions between the electrolyte and cathode materials but also increases the diffusion kinetics of lithium ions and inhibits the phase transformation on the electrode surface. Based on the beneficial structure, the O-LRM@SM electrode delivers a high discharge specific capacity and energy density (245.6 mA h g-1 and 852.1 W h kg-1 at 0.5 C), low voltage decay (0.38 V for 200 cycle), excellent rate performance, and cycle stability.
Keywords: Li-ion battery; in situ spinel coating; lithium-rich manganese cathode materials; single crystal; voltage fade.