In Situ Polymerization of Self-Healing Polyacrylamide-Based Eutectogel as Electrolyte for Zinc-Ion Batteries

Gel electrolyte has attracted extensive attentions in flexible batteries. However, the traditional hydrogel electrolyte is not enough to solve the fundamental problems of zinc anode, such as dendrite growth and side reactions, and freezing failure at temperatures below zero, which seriously restricts the development of zinc ion batteries. As a flexible energy storage device, it inevitably undergoes multiple stretches, bends, folds, or twists in daily use. Here, a self-healing and stretchable eutectogel (DA-ETG) as a solid-state electrolyte for Zinc-ion batteries was prepared by immobilizing a high-concentration ZnCl2 eutectic electrolyte into a polyacrylamide matrix through in situ polymerization under ultraviolet light. The eutectogel electrolyte showed exceptional mechanical properties with a maximum fracture strength of 0.6 MPa and high ion conductivity of 6.4×10−3 S cm−1. The in situ polymerization of the DA-ETG electrolyte in the assembly of a full solid-state zinc-ion battery increased the electrode/electrolyte interface area contact, reduced the ion transport distance between the electrode and electrolyte, minimized internal resistance, and enhanced the battery's long-term cycling stability. Using the eutectogel electrolyte, a remarkable high capacity of 580 mAh g−1 at 0.1 A g−1 was achieved by the zinc-ion battery, and a considerable capacity of 234 mAh g−1 was maintained even at 5 A g−1, showing exceptional rate performance. After 2000 cycles at 2 A g−1, the cell with the eutectogel retained a capacity of 68% with a cycling efficiency close to 98%, which demonstrated excellent cycling stability. The self-healing function enabled the prepared soft battery to be reused multiple times, with full contact between the electrode and electrolyte interface, and without device failures.