Amphiphilic ionic liquid hydrogel electrolytes with high ionic conductivity towards dendrite-free ultra-stable aqueous zinc ion batteries

Abstract

Aqueous zinc ion batteries (AZIBs) are highly promising as large-scale energy storage devices with high capacity, safety, and low cost. However, the parasitic reaction on the of Zn anode and the growth of Zn dendrites greatly prevent the practical application of AZIBs. Here, we propose an effective strategy with hydrogel electrolytes by adding dual amphiphilic ionic liquids into acrylamide, allowing for the occurrence of the following phenomena related to the Zn anode: 1) Zn2+ preferential adsorption by the amphiphilic ionic groups to regulate the electrodeposition behavior of Zn2+ on the Zn(002) crystal surface and inhibit the growth of Zn dendrites; 2) water removal from the Zn2+ solvation sheath, reducing water activity and inhibiting side reactions; 3) improved environmental adaptability of the hydrogel electrolyte through enhancing its mechanical properties and adhesion. The obtained hydrogel electrolyte has a high ionic conductivity of 41.47 mS/cm, a highly reversible Zn plating/stripping cycle of 1400 h in Zn||Zn symmetric batteries and an enhanced electrochemical performance in Zn||NVO full batteries (94 % capacity retention at 5.0 A g−1/3000 cycles). Even under harsh conditions (10 mA cm−2/10 mAh cm−2), these cells maintained excellent cycling stability. This study provides new ideas for the practical applications of AZIBs.