Using Recycled Materials in a Novel Dual Binder System for Hard Carbon Anodes: Closing the Loop Toward Sustainable Li-/Na-ion Batteries

Abstract

Hard carbon (HC) has significant potential as anode material for both Li-ion and Na-ion batteries; however, its commercialization is hindered by challenges such as poor rate capability and low initial Coulombic efficiency (ICE). Although polymeric binders constitute a small fraction of the overall electrode composition, they play a crucial role in influencing the electrochemical performance. Here, this study introduces a novel dual composite binder, combining polyacrylic acid (PAA) and polyvinyl butyral (PVB). The interaction between the COOH groups in PAA and the OH groups in PVB via hydrogen bonding prompts a cohesive polymer network resulting in electrodes exhibiting superior rate capability and high ICE in both Li-ion and Na-ion laboratory-scale cells, surpassing the performance of those with other binders tested. After optimizing the formulations by using commercial PVB, we demonstrate for the first time the use of recycled PVB, sourced from laminated glass waste, to address the lack of end-of-life programs for this material, which often ends up in landfills. Repurposing PVB waste for battery applications tackles waste management issues and contributes to innovative development of advanced, green battery materials in a circular economy approach, thus paving the way for novel waste-to-energy solutions combining high-performance with socio-economical and environmental benefits.