Constructing Nano Spinel Phase and Li+ Conductive Network to Enhance the Electrochemical Stability of Ultrahigh-Ni Cathode

The tungsten with high oxidation states (W6+) had been proved to effectively improve the electrochemical performance of ultrahigh-nickel (Ni ≥ 90 %) cathode materials due to the unique microstructures. However, the exat location and underlying action mechanism of tungsten are still not well-understood, and there have been no reports on in-situ modification from bulk to surface simultaneously for these novel cathode materials. Here, a novel integrated strategy is proposed for in-situ modification of LiNi0.9Co0.09W0.01O2 (NCW). Innovatively, the introduction of nano spinel phase and titanium pinned into the lattice further suppresses the anisotropic variation of unit cell and promotes the lithium-ion migration kinetics within the bulk. Additionally, the Li2TiO3 conductive network enhances migration kinetics across interface and protects the active material against electrolyte erosion. Furthermore, the combination of in-situ analysis and DFT calculation reveals the ordered distribution of tungsten and the suppression effects of titanium on phase transition and cobalt redox. Consequently, the titanium-modified NCW exhibits significantly improved electrochemical performance, such as capacity retention of 93.0 % at 1C after 500 cycles in pouch-type full-cell, along with stable lattice oxygen during operation.