Enhanced Structural Stability of Boron-Doped Layered@Spinel@Carbon Heterostructured Lithium-Rich Manganese-Based Cathode Materials

Abstract

Layered Li-rich 3d-transition-metal cathode materials, xLi2MnO3·(1–x)LiMO2, have increasingly triggered immense interest for their use in Li-ion batteries due to their advantages in terms of energy density. Nevertheless, poor cycle and rate performances cause limitations in practical commercial applications. We modified the material with boron bulk doping and carbon surface modification to form a B-doped layered@spinel@carbon heterostructure. Herein, B-doping can increase the lattice spacing favorable for Li+ insertion/extraction and inhibit oxygen loss successfully. The spinel layer and carbon on the surface can protect the material from corrosion due to electrolyte decomposition, which can accelerate Li+ and electron conduction and lessen the phase transition. The co-modified material reveals outstanding cycle and rate capability. Especially, it not only shows superior thermal stability at the high temperature of 45 °C, with a capacity retention rate of 83.3%, but also shows a higher discharge capacity of 108.9 mAh g–1 at the low temperature of −20 °C. Furthermore, the mechanism of the Li-rich cathode material with improved performance was also detected systematically. The proposed facile synthesis and co-modification of the boron-doped layered@spinel@carbon heterostructure can shed light on the design direction for cathode materials of lithium-ion batteries to solve the problem of electrochemical performance degradation caused by structural instability.