ABSTRACT Aqueous zinc ion batteries with high safety, high abundance and low cost of Zn have gained great attention in the field of energy storage. However, their cycling stability is mainly limited by severe side reactions and large amounts of dendrites. Lots of work have been done on electrolyte additive and construction of artificial SEI to modified zinc anode, but the electrolyte concentration regulation on the zinc anode have been overlooked. In this study, the effects of varied electrolyte concentrations from 0.1 to 5 M on the zinc anodes are studied by COMSOL simulation and electrochemical characterization. The corrosion of the zinc anode and the growth of zinc dendrites were effectively inhibited by high concentration electrolyte. The activation energy of the Zn deposition process was reduced. And, the reversibility of zinc electroplating/stripping was improved, and the symmetrical cells with moderate concentrations electrolyte (2 and 3 M) performed 1000 h with slight polarization at 1 and 5 mA cm −2 , respectively. However, the CuVO//Zn full batteries with high concentration electrolyte (5 M) achieved high specific capacity of 100 mAh g −1 over 5000 cycles at the low current density of 0.3 A g −1 and high current density of 5 A g −1 , respectively, which is slightly superior to the conditions of moderate electrolyte concentrations. And, the flexible fiber zinc ion batteries with high concentration hydrogel electrolyte showed outstanding reversibility. Regrettably, the full batteries with high concentration electrolyte showed low initial capacity. Therefore, high concentration of 5 M may be the promising solution to the full batteries regarding to the cycling stability. This indicates that gradient electrolyte concentration regulation can effectively improve the cycling stability of zinc ion batteries, and accelerate their practical applications.
Guo et al. (Wed,) studied this question.