A quasi-solid-state self-healing flexible zinc-ion battery using dual-crosslinked hybrid hydrogel as electrolyte and Prussian blue analogue as cathode material


Due to the excellent safety and less cost, aqueous Zn-ion batteries (AZIBs) have triggered extensive interest among various energy-storage systems. Here we report a quasi-solid-state self-healing AZIB by using a hybrid hydrogen which consists of dual-crosslinked polyacrylamide and polyvinyl alcohol as flexible electrolyte and cobalt hexacyanoferrate (K3.24Co3[Fe(CN)6]2·12.6H2O) Prussian Blue Analogue as cathode material. The obtained hybrid hydrogel showed a superhigh fracture strain up to 1490%, which was almost 15 times longer than the original size. Due to the fast formation of hydrogen bonds, the self-healed hydrogel from two pieces still displayed 1165% strain upon failure. As a result, the self-healed battery delivered stable capacities of 119.1, 108.6 and 103.0 mAh g‒1 even after completely cutting into 2, 3 and 4 pieces, respectively. The battery capacity recovery rates for each bending cycle exceeded 99.5%, 99.8%, 98.6% and 98.9% during four continuous bending cycles (30 times bending at 90° for each cycle), which indicates an outstanding flexibility and self-healing capability. In parallel, the hydrogel electrolyte displayed broader electrochemically stable window of 3.37 V due to the suppression of water splitting and low overvoltage during the 500 h cycling in symmetric cell. The zinc dendrite was also suppressed as evidenced in symmetric cell measurements. The assembled AZIB exhibited an initial capacity of 176 mAh g-1 upon vertical bending. The battery showed a reliable capacity of 140.7 mAh g‒1 at 0.2 A g‒1 after 100 cycles along with the Coulombic efficiency of >99%. A reliable capacity of near 100 mAh g‒1 was remained after 300 cycles at 1.0 A g‒1. The highly flexible and self-healing AZIB demonstrates great potential in various wearable electronic devices.

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