Relieving strain accumulation in ultra-high Ni cathode to achieve long cycle stability

Ni-rich cathodes with nickel content exceeding 90 % are regarded as highly promising for lithium-ion batteries (LIBs). However, the chemical-mechanical degradation caused by strain, side reactions and irreversible phase transitions will accelerate capacity fading. Especially, the mechanical degradation (cracks) caused by anisotropic strain can also accelerate chemical degradation. Herein, we effectively alleviate the anisotropic strain and the resulting cracks by Ti doping, which successfully improved the electrochemical performance of ultra-high Ni cathode. The results demonstrated that Ti doping can effectively refine the primary particles and form a tightly packed structure. Moreover, the stronger Ti-O bond incorporation into bulk efficiently stabilize lattice structure. The unique microstructure and stable lattice structure can effectively alleviate strain accumulation and chemical-mechanical degradation. Therefore, the Ti-modified cathode has the excellent electrochemical performance.