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 K x Na 5-x V 12 O 32 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 K x Na 5-x V 12 O 32 is elucidated: K substitution strengthens V 3 d –O 2 p hybridization and V 3 d –orbital electron delocalization in the K 0.147 Na 4.853 V 12 O 32 structure, enriching charge distribution and reinforcing the V 3 O 8 structure. This promots electron transfer kinetics, suppresses irreversible phase transition, and lowers the Na + diffusion energy barrier. Moreover, the reversible redox reaction of V 5+ /V 4+ 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 K 0.147 Na 4.853 V 12 O 32 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 | | K 0.147 Na 4.853 V 12 O 32 pouch cell. This strategy of electronic structure modulation offers avenues for developing high energy density stable vanadium-based cathode materials for sodium-ion batteries.