Halogen-bond chemistry-rectified hypervalent tellurium redox kinetics towards high-energy Zn batteries

Hypervalent Te redox (Te0/Te4+) in ionic liquid electrolytes (ILEs) is promising for energetic Zn batteries. However, the energy contribution of Te0/Te4+ is only one-third of the total redox-amphoteric conversion, so the contribution should be maximized for energy upgradation. The underlying kinetics-limited factor is vital but usually overlooked in previous explorations. Herein, we unlock a halogen-bond chemistry-rectified Te0/Te4+ redox with an almost maximized contribution for 700 W h kgTe-1 Zn batteries. The Zn-X bond barriers in ZnX42- (X = Cl, Br) species from ILEs play crucial roles in rectifying the Te0/Te4+ redox kinetics, especially in localized concentrated ILEs, resulting in sharply different redox conversion depths. When ZnBr42- with a weak Zn-Br bond (34.96 kcal mol-1) is used as the activator, the Te0/Te4+ redox contribution can be maximized to similar to 90.0% over 5000 cycles at 5 A g-1, 1.8-fold higher than that with the ZnCl42- activator via the strong Zn-Cl bond (102.81 kcal mol-1), and surpassing those in most aqueous systems (ca. 33.0%). This work decodes the halogen-bond chemistry-rectified kinetics to maximize the hypervalent redox contribution towards high-energy Zn batteries, which could apply to other chalcogen conversion batteries.