A review of aqueous-based binders used for cathode fabrication in lithium-ion batteries

Abstract

Lithium-ion batteries have emerged as the leading energy storage technology for electric vehicles and devices due to their high energy density and rechargeability. Although binders constitute less than 5 wt% of the electrode composition and contribute minimally to the overall LIB cost (<2%), they have a significant impact on battery performance, particularly on cycling stability. Poly(vinylidene fluoride) remains the most widely used binder in LIB cathodes, but it is typically processed using N-methyl-2-pyrrolidone, a flammable and harmful solvent. Consequently, these limitations have stimulated the research and development of environmentally sustainable and economically viable alternatives, referred to as aqueous binders. While aqueous binders have been extensively investigated for anode fabrication, their use in cathode materials is more challenging due to the higher reactivity of the cathode materials with water than that of anodes. This review presents an overview of commonly employed aqueous binders for LIB cathodes, with particular focus on carboxymethyl cellulose, poly(acrylic acid), and chitosan. Their electrochemical performances are critically evaluated in comparison with the conventional PVDF binder. The aqueous binders enhance cathode performance through improved dispersion, adhesion, and interfacial stability. They also exhibit reduced charge-transfer resistance and better Li⁺ transport due to strong ionic interactions and compact electrode formation. In addition, the challenges inherent in aqueous binder systems such as crack formation, lithium leaching and Al current collectors are examined. pH control using weak acids such as phosphoric acid and carbon-coated aluminum collectors mitigates Al corrosion and crack formation during aqueous processing. The industrial perspective of aqueous binder implementation in LIB cathode fabrication is also discussed.