A Self-Healing PVA-Linked Phytic Acid Hydrogel-Based Electrolyte for High-Performance Flexible Supercapacitors

Flexible supercapacitors can be ideal flexible power sources for wearable electronics due to their ultra-high power density and high cycle life. In daily applications, wearable devices will inevitably cause damage or short circuit during bending, stretching, and compression. Therefore, it is necessary to develop proper energy storage devices to meet the requirements of various wearable electronic devices. Herein, Poly(vinyl alcohol) linked various content of phytic acid (PVA-PAx) hydrogels are synthesized with high transparency and high toughness by a one-step freeze-thaw method. The effects of different raw material ratios and agents on the ionic conductivity and mechanical properties of the hydrogel electrolyte are investigated. The PVA-PA21% with 2 M H2SO4 solution (PVA-PA21%-2 M H2SO4) shows a high ionic conductivity of 62.75 mS cm−1. Based on this, flexible supercapacitors fabricated with PVA-PA21%-2 M H2SO4 hydrogel present a high specific capacitance at 1 A g−1 after bending at 90° (64.8 F g−1) and for 30 times (67.3 F g−1), respectively. Moreover, the device shows energy densities of 13.5 Wh kg−1 and 14.0 Wh kg−1 at a power density of 300 W kg−1 after bending at 90° and for 30 times during 10,000 cycles. It provides inspiration for the design and development of electrolytes for related energy electrochemical devices.