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‐Na 0.93 Ni 0.23 Mn 0.38 Fe 0.31 Zn 0.08 O 2 (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.