The Effect of Ionic Chaotropic/Kosmotropic Characters on Polymer Electrodes for Aqueous Dual-Ion Batteries
Abstract
Aqueous dual-ion batteries represent an emerging class of energy storage technology, characterized by their strong designability and diverse combinations due to distinct charge storage. The type of ions in the electrolytes plays a crucial role in affecting the electrochemical performance of batteries. However, such a systematic investigation into the effects of electrolyte salts has yet to be reported. This work prepares nine electrolytes to study the differences in electrochemical performance of all-organic aqueous dual-ion batteries by meticulously selecting cations/anions with varying charges and sizes. The results indicate that the chaotropic and kosmotropic characteristics of the ions, determining the polymer-water-ion interaction modes, are the primary considerations required in electrolyte design. Following a thorough comparison, 1M Zn(OTf)2 was identified as the optimal electrolyte for all-organic aqueous dual-ion batteries, demonstrating a capacity retention of 68.4% after 5000 cycles. This work provides intuitive experimental data illustrating the roles of electrolytes in aqueous dual-ion batteries and highlights the importance of electrolyte design in related research fields.