Abstract
Supercapacitors are a very active research topic. However, liquid electrolytes present several drawbacks on security and packaging. Herein, a gel polymer electrolyte was prepared based on crosslinked renewable and environmentally friendly soybean protein isolate (SPI) and hydroxyethyl cellulose (HEC) with 1.0 mol L−1 Li2SO4. Highly hydrophilic SPI and HEC guaranteed a high ionic conductivity of 8.40 × 10−3 S cm−1. The fabricated solid-state supercapacitor with prepared gel polymer electrolyte exhibited a good electrochemical performance, that is, a high single electrode gravimetric capacitance of 91.79 F g−1 and an energy density of 7.17 W h kg−1 at a current density of 5.0 A g−1. The fabricated supercapacitor exhibited a flexible performance under bending condition superior to liquid supercapacitor and similar electrochemical performance at various bending angles. In addition, it was proved by an almost 100% cycling retention and a coulombic efficiency over 5000 charge–discharge cycles. For comparison, supercapacitors assembled with commercial aqueous PP/PE separator, pure SPI membrane, and crosslinked SPI membrane were also characterized. The obtained gel polymer electrolyte based on crosslinked SPI and HEC may be useful for the design of advanced polymer electrolytes for energy devices.
Highlights
Supercapacitor (SC) is considered as an electrochemical energy storage device with a great potential due to its high-power, long cycle life, low environmental impact, and high safety at present [1].Recently, the development of flexible solid-state supercapacitors fabricated with polymer electrolytes that can be used in wearable electronic devices has attracted more attention.It is well known that the energy density of a supercapacitor is determined by the specific capacitance and squared operating voltage window [2,3]
The absorption peaks of characteristic group of protein were observed at 1626 cm−1, 1537 cm−1, and 1223 cm−1 and correspond to amide
A transparent, flexible, biodegradable membrane based on crosslinked soybean protein isolate (SPI) and hydrophilic
Summary
The development of flexible solid-state supercapacitors fabricated with polymer electrolytes that can be used in wearable electronic devices has attracted more attention. It is well known that the energy density of a supercapacitor is determined by the specific capacitance and squared operating voltage window [2,3]. To improve the energy density, tremendous efforts have been devoted to developing novel electrode materials to elevate the specific capacitance [4,5,6,7,8,9,10]. Apart from the electrodes, electrolyte is one of the key components of a supercapacitor, that can significantly affect the operating voltage as well as lifespan and safety of supercapacitors [11,12,13].
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