Flexible batteries with high energy storage and stretching/bending capabilities have attracted great research interest in recent years to support the development of flexible electronics such as wearable sensors for health monitoring and flexible displays. Compared to Li-ion batteries (LIBs), zinc-ion batteries (ZIBs) have a lower cost and are safer to use while still have a good energy density. Among various flexible electrolytes, hydrogels are very promising for flexible ZIBs due to their high ionic conductivity, good flexibility, and intimate contact with the battery electrodes. Current generation of hydrogel electrolytes show the drawbacks of poor low-temperature performance and loss of flexibility due to the presence of water in the hydrogels. The polymers used to make the hydrogels are also derived from petroleum. The goal of this project is to develop robust, flexible, ionic conductive, and freeze-resistant electrolyte gels based on soy protein isolate (SPI) and polyvinyl alcohol via a novel chemistry. The breakage and recovery of the bonds render the hydrogel network desired flexibility and reversibility. Chemicals will be introduced in the gels to: 1) depress the freezing temperature of SPI based hydrogel electrolytes and preserve their flexibility in low temperatures (i.e. -30 °C), 2) increase ionic conductivity, and 3) improve the mechanical properties of the SPI based hydrogel electrolytes. The mechanical, electrical and thermal properties of the electrolytes will be studied and the optimum formulations/processing conditions will be determined. Prototype ZIBs will be made and tested using the optimized hydrogel electrolytes.

To develop a soy protein isolate (SPI)-based gel that is freeze-resistant, robust, highly
deformable, and ionic conductive. The gel will be a suitable electrolyte material for flexible
ZIBs.

• SPI-based electrolyte gels that have the desirable mechanical and electrical properties under
normal and extreme conditions, e.g., sub-zero temperatures and under stretching, bending, and
rolling.
• Fabrication and user guidelines of gels that are used as an electrolyte in production of flexible
ZIBs.

Update:
Report sent to PM

Update:
Report was submitted to PM on 6/30/2023

The global market for flexible batteries is estimated at US$294.2 Million in 2020, and is projected to reach US$2.4 Billion by 2026, growing at a CAGR of 40.8%. An array of high-value synthetic polymers are used in production of flexible electronics and batteries. There are limited studies but with very promising results revealing the capability of natural polymers including soybean derivatives in flexible electronics. By conducting this project, soy-based materials as a cost-effective and efficient feedstock will be introduced to the fast-growing and very high value-added electronic market. This could enable large-scale and high-value use of soy protein in the near future and bring additional income to ND soybean farmers.