Self-healable chitosan-based polymer binder for anode in lithium-ion batteries

To enhance the performance and durability of lithium-ion batteries, the development of effective binder materials in the anode is crucial, with eco-friendliness being an additional consideration. This study presents a bio-based and self-healable polymeric binder designed for use in graphite-based anodes to achieve enhanced battery performance. The binder was synthesized via a Schiff base reaction between chitosan and a vanillin-derived linker, forming imine bonds that establish a self-healable 3D network. The bio-based binder effectively holds the graphite particles together while also providing excellent mechanical strength, thermal stability, and strong adhesion to the copper foil. Notably, it demonstrated self-healing behavior, with mechanical recovery exceeding 90 % after damage. Thermogravimetric analysis confirmed high thermal stability up to 300 °C, while the binder exhibited excellent tensile adhesion strength (ca. 21 kPa). Both coin and pouch cells fabricated with the bio-based binder achieved a specific capacity of 161.2 mAh g −1 and retained 81 % of their capacity after 250 cycles. Coulombic efficiency remained consistent at above 92 % even after 250 cycles, indicating no side reactions. Even at a high current density of 1.0C, the cells maintained approximately 50 % of their original capacity measured at 0.3C, showcasing excellent rate capability. Electrochemical impedance spectroscopy revealed low interfacial resistance, further validating the stability of the chitosan-based binder. We anticipate that this class of bio-based binders will not only extend the service life of lithium-ion batteries but also make a significant contribution to greener, safer energy storage technologies. • Chitosan-based binder for lithium-ion batteries: Developed a sustainable, bio-derived polymer binder as an alternative to conventional PVDF. • Enhanced electrochemical performance: Achieved improved capacity retention and cycling stability in graphite and/or anode electrodes. • Mechanical robustness: Demonstrated strong adhesion and flexibility, accommodating electrode volume changes during cycling. • Functional properties: Binder exhibited self-healing behavior, contributing to battery durability. • Environmentally friendly approach: Utilizes a biodegradable, renewable material, supporting greener battery manufacturing.