Aqueous Na-ion batteries and Zn-ion have attracted tremendous research interest in recent years, due to its potential for high output performance with low cost. To combine their advantages, aqueous Na-Zn hybrid ion batteries are proposed recently, targeting at high-voltage and high-capacity output. However, lack of appropriate electrolyte greatly restricted the hybrid battery performance since large electrochemical window is required by the intercalation of Na ion.
Recently the HKU Department of Mechanical Engineering team led by Professor Dennis Leung and their collaborators from Imperial College London, Loughborough University and Beihang University reported a high-performance Na-Zn hybrid ion battery boosted by a “water-in-gel” NaCl/ZnSO4/Sodium Alginate electrolyte with large-electrochemical-window. Besides high-efficiency transport of cation due to carboxylate groups, the water-in-gel electrolyte achieves an interesting multi-ion (Na+, Zn2+ and ZnCl42-) intercalation chemistry. The hybrid battery exhibits a high discharge plateau of 2.1V together with a high discharge capacity of 260 mAh g-1, outperforming most state-of-art aqueous Na-ion batteries and aqueous Zn-ion batteries. Furthermore, an ultra-high capacity of 1250 mAh g-1 can be obtained by taking advantage of the Zn/O2 reaction. The paper was recently published in Advanced Functional Materials under the title “High-performance aqueous Na-Zn hybrid ion battery boosted by “water-in-gel” electrolyte”.