Hydrogen-Bond Regulated Water Confinement Strategy Enables High-Temperature-Resistant Hydrogel Film for Flexible Rechargeable Batteries

The poor high-temperature adaptability of the hydrogel electrolyte film limits the performance of hydrogel-based rechargeable batteries. Especially, the deterioration of electrochemical windows at high temperatures leads to a fast decay of cyclic stability. Herein, a hydrogel film containing 6.42 wt % water is successfully prepared, which exhibits room temperature conductivity of 1.38 mS cm^-1 and a broad electrochemical window up to 2.53 V. These features are beneficial for the cycling performance of the hydrogel-based batteries, which demonstrate 76.9% capacity retention after 1000 cycles at 2 C. Additionally, this hydrogel film has a low thickness swelling ability of 4.8%, making it suitable for use in the multiple-coating method to construct an all-in-one structure for flexible rechargeable batteries. This cell exhibits satisfying electrochemical performance, even during bending, after soaking, or at -20 °C. Furthermore, the hydrogel-based full cell maintains 85.0% of its initial capacity after 100 cycles at 60 °C, and can even work normally at 80 °C. This improved high-temperature tolerance can be attributed to the reconstructed H-bond network within the hydrogel film. This study provides great potential for developing flexible rechargeable batteries with a high temperature tolerance for wearable energy devices.