Eco-Friendly Binders for High-Capacity Silicon Anodes and Sustainable Metal-Ion Batteries: A Focus on Water-Based and Bio-Based Alternatives

The rapid growth of electric vehicles (EVs) and electronic devices has significantly increased the demand for high-performance and sustainable battery technologies. Among the key components of metal-ion batteries, including lithium-ion batteries (LIBs), binders play a crucial role in ensuring electrode stability and reliable performance. However, conventional binders, often derived from synthetic polymers and organic solvents, fall short of meeting the sustainability requirements for next-generation energy storage systems (ESSs). To address these challenges, eco-friendly binders have emerged as innovative solutions for advancing sustainable battery technologies. This review explores the evolution of eco-friendly binders, focusing on their dual role in enhancing battery performance and promoting environmental sustainability. Key design parameters for eco-friendly binders are discussed, alongside recent advancements in water-soluble binders that eliminate the need for hazardous solvents. Additionally, nature-derived binders sourced from renewable resources, such as plants, milk, seaweed, and corn are highlighted for their unique properties, benefits, and performance metrics. While prior reviews have provided valuable insights into the mechanical and/or chemical aspects of binder development, this work aims to complement those efforts by offering a broader perspective that incorporates sustainability-driven classification, solid-state compatibility, and high-mass-loading electrode applications. Challenges related to scalability and performance consistency are thoroughly analyzed, while future directions emphasize the development of biodegradable synthetic binders and their integration into next-generation batteries, including all-solid-state and wearable systems. Beyond improving battery performance, these eco-friendly and biodegradable binders have the potential to reduce the environmental impact of spent batteries. This review offers valuable insights into the development of sustainable binders and aims to inspire advancements that will revolutionize the battery industry, supporting a circular economy in energy storages.