Sustainable lithium-ion battery separators based on cellulose and soy protein membranes

The food industry produces millions of tons of natural by-products. Through this study, we followed an environmentally friendly strategy using discards, such as soy protein isolate (SPI) from soya oil production and marine cellulose (Cell) from the agar industry, in order to achieve added-value applications. In particular, this work focuses on the development of membranes based on soy protein and cellulose, and their validation as battery separator membranes toward sustainable energy storage systems. SPI membranes with Cell show excellent compatibility with the electrolyte based on physical interactions. These physical interactions favor the swelling of the membranes, reaching swelling values of 1000% after three days in the liquid electrolyte. The membranes are thermally stable up to 180 degrees C. After being subjected to the liquid electrolyte, it is observed that the microstructure of the membranes change, but the porous structure is maintained, while the materials remain easy to handle. The ionic conductivity value, lithium transference number and battery performance in cathodic half-cells are similar to 5.8 mS.cm(-1), 0.77, and 112 mAh.g(-1) at 1C-rate, respectively. Overall, considering environmental issues and circular economy, it is proven that it is possible to obtain more sustainable high-performance lithium-ion batteries based on waste materials.

Automated summary

This study develops membranes based on soy protein and cellulose from waste materials, which are used as battery separator membranes for sustainable energy storage systems. The membranes show excellent compatibility with the electrolyte, good swelling properties, and thermal stability. They also demonstrate high ionic conductivity, lithium transference number, and battery performance.