Multi-Doped (Ga,B) Li[Ni0.885Co0.100Al0.015]O2Cathode

Abstract

A Ni-rich layered cathode, Li[Ni0.885Co0.100Al0.015]O2 (NCA89), was compositionally modified to demonstrate that multiple doping can effectively stabilize the delithiated structure. Incorporation of B and Ga into the cathode substantially improved the cycling stability of the NCA89 cathode. The 0.25 mol% B- and 0.75- mol% Ga- doped NCA89 cathode retained 91.7% of its initial capacity after 100 cycles while delivering a discharge capacity of 222.2 mAh g-1 at 0.1 C, whereas the pristine NCA89 cathode retained only 79.4% of its initial capacity. The multi-doped cathode exhibited excellent long-term cycling stability; it retained 83.4% of the initial capacity after 500 cycles compared to the P-NCA89 cathode that retained only 62.4%. We attributed the improved cycling stability to the incorporation of B, which modified the surface energy to produce a highly aligned microstructure conducive to relieving anisotropic internal strain, and Ga, which provided structural and chemical stability to the O-TM-O slab. Co-doping with Ga and B is an effective strategy to improve the cycling stability of Ni-rich layered cathodes, which are projected to be the power source for next-generation electric vehicles.