Anion Engineering of LiVPO ₄ F _(1‐x) O _x Enables Fast‐Charge and Wide‐Temperature Lithium‐Ion Batteries

Abstract The Tavorite‐structured polyanionic lithium‐ion batteries (LIBs) cathode material LiVPO 4 F (LVPF) shows great promise for high‐power applications due to its excellent safety and rapid charge–discharge capabilities. This study introduces a novel oxygen‐substituted variant LiVPO 4 F (1‐x) O x , synthesized through a one‐step hydrothermal method, producing a nanosheet structure. Advanced characterization confirms the formula of LiVPO 4 F 0.69 O 0.31 (LVPFO). Electrochemical evaluations indicate that replacing part of F with O lowers charge–discharge plateau voltage and polarization at high current densities. The material exhibits discharge capacities of 156.6–86.4 mAh g −1 at various rates (0.1–15 C). It retains 90.1% of its capacity after 1000 cycles at 15 C. LVPFO further demonstrates fast ion/electron transport and excellent structural stability across an extensive temperature range (−40–50 °C). An experimental full‐cell with carbon‐coated TiNb 2 O 7 (TNO@C) anode and LVPFO cathode achieves a capacity of 127.5 mAh g −1 and an energy density of 319 Wh kg −1 at 0.5 C, and a good capacity retention of 73.7% over 1000 cycles at 10 C. Density Functional Theory (DFT) calculations indicate that the partial substitution of F with O endows LVPFO with a lower Li + diffusion energy barrier and improves electronic conductivity. This study offers valuable insights for the advancement of high‐energy and power‐density cathode materials in LIBs.