Local electronic regulation of Na5V12O32 cathode suppressing structural distortion toward enhanced sodium storage.

High-voltage layered oxide cathodes have received extensive attention for sodium-ion batteries owing to their potential high energy and power densities, but their stabilization remains a universal challenge. Herein, a stable high-voltage KxNa5-xV12O32 cathode is designed by synergistically tuning the irreversible phase and oxygen vacancies through the substitution of Na with K. The functional mechanism regulating the electronic structure of KxNa5-xV12O32 is elucidated: K substitution strengthens V 3d-O 2p hybridization and V 3d-orbital electron delocalization in the K0.147Na4.853V12O32 structure, enriching charge distribution and reinforcing the V3O8 structure. This promots electron transfer kinetics, suppresses irreversible phase transition, and lowers the Na+ diffusion energy barrier. Moreover, the reversible redox reaction of V5+/V4+ is significantly enhanced, delivering 250.1 mA h g-1 (1.5-4.3 V vs. Na/Na+), which increases the average operating voltage from 4.0 to 4.3 V and boosts the overall energy density. Consequently, the K0.147Na4.853V12O32 electrode significantly enhances cycling performance, retaining 98.2% of the capacity after 1000 cycles at 1300 mA g-1 and enabling stable cycling with 98.7% retention after 300 cycles in a hard carbon | | K0.147Na4.853V12O32 pouch cell. This strategy of electronic structure modulation offers avenues for developing high energy density stable vanadium-based cathode materials for sodium-ion batteries.