Lithium nickel oxide (LiNiO2) is a promising next-generation cathode material for lithium-ion batteries (LIBs), offering exceptionally high specific capacity and reduced material cost. However, the poor structural, surface, and electrochemical stabilities of LiNiO2 result in rapid loss of capacity during prolonged cycling, making it unsuitable for application in commercial LIBs. Herein, we demonstrate that incorporation of a small amount of niobium effectively suppresses the structural and surface degradation of LiNiO2. The niobium-treated LiNiO2 retains 82% of its initial capacity after 500 cycles in full cells with a graphite anode compared to 73% for untreated LiNiO2. We utilize a facile method for incorporating niobium, which yields LixNbOy phase formation as a surface coating on the primary particles. Through a combination of X-ray diffraction, electron microscopy, and electrochemical analyses, we show that the resulting niobium coating reduces active material loss over long-term cycling and enhances lithium-ion diffusion kinetics. The enhanced structural integrity and electrochemical performance of the niobium-treated LiNiO2 are correlated to a reduction in the formation of nanopore defects during cycling compared to the untreated LiNiO2.
Keywords: electrochemistry; high-nickel layered oxide; lithium niobate coating; lithium-ion batteries; niobium doping.