In-situ Construction of Spinel Coating on the Surface of Lithium-Rich Manganese Based Single Crystal for Inhibiting Voltage Fade.

Layered lithium-rich transition metal oxides (LRM) have been considered as the most promising next generation cathode material for lithium ion battery. However, the 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 O-LRM@SM composite with a 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 phases domains, which is the most reason for capacity fading. On the other hand, the spinel membrane not only prevents the side reactions between 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, O-LRM@SM electrode deliver a high discharge specific capacity and energy density (245.6 mAh g-1 and 852.1 Wh kg-1 at 0.5 C), low voltage decay (0.38 V for 200 cycle), excellent rate performance and cycle stability.