Bifunctional Hydrated Gel Electrolyte for Long-Cycling Zn-Ion Battery with NASICON-Type Cathode

Abstract

Aqueous Zn-ion batteries are promising and safe energy storage technologies. However, current aqueous electrolyte Zn-ion battery technology is hindered by undesirable reactions between the electrolyte and electrodes, which can lead to Zn dendrite growth, gas evolution, and cathode degradation. In this study, a hydrated gel electrolyte (HGE) that combines adiponitrile (ADN) and Zn(ClO4)2·6H2O in a polymeric framework is created. ADN is found to stabilize the interface between the electrolyte and anode/cathode, enabling smooth Zn stripping/plating and reducing parasitic reactions. The HGE is simple to fabricate, inexpensive, safe, and flexible. Zn/HGE/Zn symmetrical cells can cycle more than 1000 h at 0.5 mA cm−2 and 2000 h at 0.2 mA cm−2 without short-circuiting, indicating effective suppression of Zn dendrites. Moreover, with a NASICON-type Sr-doped Na3V2(PO4)3 (SNVP) cathode, a Zn/HGE/SNVP full cell can be cycled over 8000 times at 10 C while retaining a high capacity of 90 mAh g−1.