Rational structure of rod-like single crystal LiNi0.9Co0.05Mn0.04Al0.01O2 cathode for superior-stable lithium-ion battery

Abstract

Ultra-high nickel layered LiNixCoyMn1-x-yO2 (U-NCMs, x≥0.9) materials are promised to be the ideal cathode materials for lithium-ion batteries. Conventional polycrystalline U-NCMs suffers from rapid capacity degradation and structural instability during cycling. As an attractive alternative, single-crystal (SC) U-NCMs materials exhibit better structure stability and stable cyclic ability due to the eliminated intergranular cracking and improved Li+ transportation. However, it's difficult to prepare SC U-NCMs with good electrochemical properties using conventional spherical hydroxide precursors. Herein, rod-like SC LiNi0.9Co0.05Mn0.04Al0.01O2 (R-SC NCMAs) materials with good-layered structure, smooth surface and uniform element distribution are synthesized by a simple solvothermal method. Disordered phase transition and interface side reactions are effectively prevented in R-SC NCMAs due to the exposed a large area of (010) crystal planes and stronger structure of rod-like single crystal morphology, intergranular cracks, surface pulverization. Thus, the R-SC NCMAs delivers superior structure stability and Li+ diffusion kinetics. Consequently, the R-SC NCMAs material exhibits an excellent rate performance (reaching discharge capacity of 156 mAh g−1 at 5 C) and cycling stability (achieving discharge capacity retention of 95.1% at 0.2 C after 100 cycles). This study provides a facile and effective way to achieve superior-stable SC NCMAs for high-energy density LIBs.