Electrocatalytic Selenium Redox Reaction for High?Mass?Loading Zinc?Selenium Batteries with Improved Kinetics and Selenium Utilization

Batteries usually deliver mass loading-dependent electrochemical performance. Taking the selenium cathode as an example, Se reaction kinetics, utilization, and cycling lifespan seriously deteriorate with increased loading. Here, electrocatalytic reduction/oxidation strategy to realize high-Se-loading Zn||Se batteries fast kinetics high utilization is proposed. Specifically, synergetic effects of Cu Co transition-metal species inside channel structure host can effectively immobilize catalytically convert Sen during cycling, which thus facilitates 6-electron (Se4+ ? Se2–) conversion kinetics. In particular, Cu[Co(CN)6] exhibits a remarkably low energy barrier (1.63 kJ mol–1) Tafel slope (95.23 mV dec–1) for reduction, highest current response oxidation. Accordingly, Zn battery employing Se-in-Cu[Co(CN)6] delivers capacity 664.7 mAh g–1 at 0.2 A g–1, excellent rate capability 430.6 achieved even 10 long-cyclic life over 6000 cycles 90.6% retention. Furthermore, A-h-level (?1350 mAh) pouch-type loading (?12.3 mg(Se) cm–2) shows 83.3% outstanding cyclic stability 89.4% initial retained after 400 exceeding 98% Coulombic efficiency.