Abstract
High-voltage LiNi0.5Mn1.5O4 (LNMO) cathodes offer high energy density but suffer from rapid degradation, particularly at elevated temperature, driven by electrolyte decomposition, hydrofluoric acid (HF) formation, and transition metal dissolution. While extensive efforts have focused on stabilizing cathode materials, strategies capable of directly regulating these reactive species within the electrode environment remain limited.
Here, we introduce the concept of binders designed to function as an active interfacial regulator that suppresses key degradation pathways in high-voltage lithium-ion batteries. Using water-processable binders, we demonstrate that lithiated poly(acrylic acid) (LiPAA) simultaneously scavenges dissolved transition metals and neutralizes HF, thereby mitigating electrode cross-talk. Chemical uptake experiments confirm strong Mn2+ binding and HF removal, while electrochemical analysis in LNMO‖graphite cells with LiPAA exhibit improved cycling stability at room temperature and 50 °C, reduced impedance growth, as well as significantly lower transition metal deposition on the anode. These results establish binder chemistry as a powerful and scalable approach to control interfacial degradation processes, highlighting the potential of functional binders as active components for stabilizing high-voltage lithium-ion batteries.