Surface Stabilization of Cobalt-Free LiNiO 2 with Niobium for Lithium-Ion Batteries.

Lithium nickel oxide (LiNiO 2 ) 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 LiNiO 2 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 LiNiO 2 . The niobium-treated LiNiO 2 retains 82% of its initial capacity after 500 cycles in full cells with a graphite anode compared to 73% for untreated LiNiO 2 . We utilize a facile method for incorporating niobium, which yields Li x NbO y 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 LiNiO 2 are correlated to a reduction in the formation of nanopore defects during cycling compared to the untreated LiNiO 2 .