A Universal Strategy for Optimizing Surface Residual Alkali via Binders to Enhance the Electrochemical Performance of Sodium-Ion Batteries.

Layered transition metal oxides (LTMOs) cathodes have attracted widespread attention in sodium-ion batteries (SIBs) owing to high capacity, low-cost. However, the surface residual alkali species on cathode materials lead to severe capacity attenuation and sluggish kinetics. Herein, we propose a facile one-step binder modification strategy, utilizing binder of polyacrylic acid (PAA) with rich -COOH group to convert surface residual alkali on the P2-Na0.93Ni0.23Mn0.38Fe0.31Zn0.08O2 (P2-NFMZ) cathode. Results reveal that PAA-modified P2-NFMZ delivers excellent electronic conductivity and outstanding cycling stability. More importantly, the PAA modification strategy exhibits broad generalizability toward O3-NFM111 cathodes suffering from surface residual alkali issues. Furthermore, we report a universal optimization strategy. Benefiting from its broad compatibility with P2/O3 layered cathodes and remarkable full-cell electrochemical behaviors, this strategy provides an effective approach to mitigate residual alkali accumulation and interfacial instability of LTMOs toward practical battery deployment.