Fig. 2: Physicochemical and electrochemical characterizations of ZnCl₂-based aqueous electrolyte solutions at various concentrations.

a CV curves of the I-containing electrode in ZnCl₂ electrolytes with different concentrations at a scanning rate of 1 mV s^–1. b Cycling stability of ClRR in 10, 20, 30 m ZnCl₂ electrolytes at 0.5 A g_I2⁻¹, respectively, and the specific capacity was calculated based on the mass of I₂ in ZnǁCl-I pouch cells at 25 °C. c Ex situ Raman profiles revealing the different hydrogen-bond networks of water in different electrolytes after 100 cycles corresponding to b. d Raman results of uncycled electrolytes with different concentrations, in which the deconvolution peaks of strong hydrogen bonds (H-bonds), weak H-bonds and non-H-bonds are centred at 3228 cm⁻¹, 3432 cm⁻¹, and 3594 cm⁻¹, respectively, for the 1 m ZnCl₂ electrolyte. e Rate performance of Zn | |Cl-I cells from 0.5 to 0.5 A g_I2^-1 and the corresponding GCD curves f. g Cycling stability of the Cl-redox reaction after 300 cycles at 0.5 A g_I2^-1.