Microstructure Engineered Ni-Rich Layered Cathode for Electric Vehicle Batteries

Abstract

The Nb doping of Li[Ni0.855Co0.13Al0.015]O-2 (NCA85) modifies its primary particle morphology to allow precise tailoring of its microstructure. The Nb dopant (1 mol%) elongates the primary particles and aligns them in the radial direction, creating a configuration that effectively dissipates the abrupt internal strain caused by H2 <-> H3 phase transitions near the charge end. The negation of the internal strain substantially improves the long-term cycling stability achieved by the Nb-doped NCA85 cathode; it retains 90% of its initial capacity after 1000 cycles while an undoped cathode retains 57.3%. Moreover, the enhanced mechano-chemical stability of the Nb-doped NCA85 cathode enables fast charging; accordingly, the Nb-doped NCA85 cathode cycles stably for 500 cycles even when charged at 3 C (full charge is achieved in 20 min). The Nb-doped cathode also demonstrates enhanced chemical and structural stability during calendar aging and under thermal load. The simple strategy of introducing Nb ions during the lithiation of NCA85, proposed in this paper, represents an effective solution that guarantees sufficient battery life, fast charging, and safety without compromising battery capacity for next-generation electric vehicles.