November 2nd news, Researchers at Tsinghua University have developed a renewable material made from soy protein, which is expected to provide an efficient and long-lasting power source for the next generation of solid-state batteries.
Lithium-ion batteries, widely used in smartphones and electric vehicles, are set to be succeeded by solid-state batteries. The core innovation of solid-state batteries lies in the electrolyte — a crucial component that acts as a bridge between electrodes, allowing metal ions to pass through and generate electricity. As the name implies, solid-state batteries replace traditional liquid electrolytes with solid materials, enabling faster charging speeds and potentially doubling energy storage capacity.
Although solid-state batteries still require further optimization in terms of performance and cost to gain market competitiveness, a highly-anticipated solution in recent years has been the use of renewable materials to manufacture solid electrolytes. This approach not only helps reduce the environmental impact of battery production but also enhances both the performance and safety of the batteries.
Our research has propelled the application of green, sustainable biomass materials in the field of battery science and technology, contributing to the building of a cleaner, more efficient, and sustainable future. Professor Yang Shen, one of the authors of the research paper from Tsinghua University, stated, "Compared to traditional solid electrolytes, the high-performance electrolytes developed using renewable soy protein can reduce waste generation and significantly decrease the environmental impact."
Soy protein is a renewable, cost-effective material that is easy to mass-produce, making it an ideal candidate for manufacturing eco-friendly batteries. Its natural structure allows ions to pass through, and it is also convenient for scientists to chemically modify, enabling flexible performance adjustments for various applications.
Shen Yang pointed out, "Soy protein is currently mainly used in the food and healthcare industries. Its ease of access, non-toxicity, and biodegradability make it a promising candidate for other fields as well."
The Shenyang team chemically modified soybean protein to make it suitable for batteries, enhancing its intrinsic conductivity and facilitating smoother lithium ion migration. The resulting material forms a three-dimensional network structure with alternating hard and soft layers, combining high strength with flexibility, making the electrolyte both robust and elastic.
Solid-state lithium batteries assembled with this soy-based electrolyte have successfully completed over 2000 charge-discharge cycles at 60°C. When the temperature rises to 120°C, the battery retains nearly 75% of its initial capacity after more than 800 charge-discharge cycles, demonstrating promising applications for reliable operation in high-temperature environments. In contrast, traditional lithium-ion batteries typically become unstable and experience significant performance degradation above 60°C, posing safety risks such as the leakage of toxic and highly flammable substances.
Moreover, this soy-based material is poised to address a critical challenge in current electrolyte research: during the battery charging and discharging process, a chemical reaction may occur between the electrolyte and the electrode, forming an interface layer. If this interface layer cannot maintain stability, it will continue to thicken with each cycle, gradually diminishing the battery's performance.
Batteries made from soy-based materials form a thin and even interface layer between the electrolyte and the electrode, maintaining stability over the long term. More importantly, this interface layer boasts excellent flexibility, allowing it to expand and contract with the volume changes during the battery's charging and discharging process, effectively preventing cracks from forming.
Life cycle assessments reveal that the production process of soy-based materials, compared to other organic electrolyte materials that perform well in solid-state batteries, has a lower environmental impact in terms of acidification effects, carcinogen release, and fossil fuel consumption. Additionally, the soy protein electrolyte significantly reduces the release of toxic or volatile compounds during use.
Shen Yang stated, "These results indicate that materials based on soybeans have great potential in the field of energy storage, offering a highly promising technical path for the development of solid electrolytes from biomass sources."
Despite the material requiring further optimization and facing challenges in mass production, soy protein could one day become a key foundational material for long-lasting, environmentally friendly batteries. Especially in the fields of electric vehicles and electronic devices, Shen Yang and his team believe its application prospects are vast, particularly in scenarios where batteries need to operate stably under extreme temperature conditions.
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