Surface titanium enrichment engineering improves the structural stability and cycle life of Ni-rich Co-free cathode materials for lithium-ion batteries

Increasing nickel content and eliminating cobalt are important development directions for layered cathode materials, as they can enhance energy density and reduce costs. However, cobalt plays a crucial role in improving the structural stability of materials during lithiation/de-lithiation, and higher nickel content also reduces the structural stability. This study employs a facile surface titanium enrichment process to mitigate the negative effects brought by high nickel content and cobalt removal. In situ XRD characterization reveals that surface titanium enrichment reduces the extent of structural changes during lithiation/de-lithiation while increasing the reversibility of phase transitions. As a result, the cycling stability of the modified material is improved, with its capacity retention after 300 cycles at 2 C increasing from 66.2% to 77.4%. Furthermore, the rate capability of the modified material is also enhanced, delivering a capacity of 150.6 mAh g -1 at 5 C. This strategy provides a feasible technical reference for the practical application of nickel-rich, cobalt-free cathode materials. • A facile surface titanium enrichment method for modifying LiNi 0.9 Mn 0.1 O 2 . • In situ XRD reveals the enhanced structural stability after modification. • The surface Ti enrichment enhances the cycle life of LiNi 0.9 Mn 0.1 O 2 . • The electrode reaction kinetics is improved by surface Ti enrichment.