Bio-Sourced Alternatives for Lithium-Silicon Anodes (BALSA)

Li-ion batteries are growing in demand to support the green shift to a sustainable economy. This means that important materials can become limited in supply, meaning they are called critical raw materials. Some of these critical raw materials can come from politically unstable countries or from places using unethical labor practices. One potential solution to this problem is to develop a battery which is mostly made of materials that come from biological sources, like plants. The BALSA project aims to achieve this for several major parts of common Li-ion batteries. First, it will examine how to obtain silicon, a next-generation battery anode, from barley husks instead of using graphite which is mined in China. The silicon will also have small pores in it so the silicon has space to expand when we put lithium in it. Second, the porous silicon will be combined with carbon nanofiber aerogel. The aerogel is like a woven pattern of very thin fibers made of carbon. The aerogel helps the silicon conduct electricity instead of using copper, and the carbon fibers can also be made from plant fibers. Lastly, the BALSA battery project will use an electrolyte made with an ionic liquid, which is safer than normal battery electrolytes that can burn. Other materials also derived from plants like silicon dioxide and cellulose fibers will be added to the electrolyte to help with stability. Thus, the BALSA battery can become much environmentally friendly but perform as a good, safe battery with lower cost, lower carbon footprint, and better recyclability. To know exactly how environmentally friendly the BALSA battery will be, the project will also do a life cycle analysis which looks at the carbon footprint of every step of making the BALSA battery. It will support the European Green Deal, a more circular economy, and support job creation in rural, agricultural areas by making high value materials from plants and plant waste, like barley husks.

The BALSA project aims to develop a fully bio-based Li-ion battery (LIB) anode and quasi-solid-state electrolyte, in which all the active and supporting materials are derived from biological sources, i.e., from plants. To achieve this goal, the project proposes combining mesoporous Si derived from barley husks, a cellulose-based carbon nanofiber aerogel as a free-standing support, and a bio-derived quasi-solid-state composite electrolyte containing a poly(ionic liquid) scaffold, bio-based fillers, and ionic liquid additives. The developed battery anode is combined with environmentally friendly cathode to create a lab-scale prototype, reducing the dependence of battery chemicals on the critical raw materials like Co and Cu. The developed LIB is expected to have comparable performance compared to the state-of-the-art, but with significantly lower cost and carbon footprint and the potential for recyclability. In order to properly compare and evaluate the project’s result, a holistic life cycle assessment (LCA) incorporating circular economy pathways will be conducted to benchmark the reductions in carbon footprint from the production of the BALSA battery. The performance can be contextualized by the carbon footprint, thereby meeting the goals of the European Green Deal, circular economy, and supporting skilled job creation in rural, agricultural regions. The technology at the beginning of the project is at TRL 2, as individual components have already been demonstrated in the laboratory. The target by the end of the project is TRL 4, with a lab-scale pouch cell prototype to be assembled showing some individual components of the BALSA battery to have industrial relevance. The industrial participation of Talga for anode manufacturing, testing, and materials benchmarking and of Performance Biofilaments Inc. for cellulose-based carbon nanofibre production, offer insight and perspective on commercial exploitation of the project’s results in the aftermath of the project.