The activation of four-electron transfer behavior through I-/I0/I+ conversion reactions is crucial for the development of high-energy-density zinc-iodine batteries (ZIBs) but is hindered by the rapid hydrolysis of I+ in protic solvents. Theoretically, the directionality and modifiability of halogen bonds (XBs) can be used to regulate the hydrolytic disproportionation of I+. Given that the conventional coordination configuration is not applicable because of the locking of the XB donor (I+), the inversion of the coordination configuration to establish a charge distribution preanisotropy (σ-holes) and thus realize XB-stabilizing electron-scale coordination is vital for breaking down the barriers existing in protic solvents. To counteract external environmental disturbances, the cohesive energy differentiation based on the Hansen parameter creates the non-identical-frequency molecular vibrations of additives with water. Herein, an electrolyte additive (chloroacetonitrile, ClAN) with these advantages enabled the redox coupling of I-/I0/I+ at a very low salt concentration (4 molar kg-1). The corresponding ZIB exhibited a specific discharge capacity of 175.7 mA h g-1 after 4000 cycles at 2 A g-1 and showed an extremely high specific capacity at high rates (133.1 mA h g-1 at 50 A g-1). This work establishes a generalized framework and new horizons for halogen batteries with multiple electron transfers.
Qiu et al. (2025) studied this question.