K-ion preintercalated MnO₂ nanorods as a high-rate cathode material for aqueous zinc-ion batteries

The integration of Zn/α-MnO₂ in aqueous zinc-ion batteries (ZIBs) has emerged as a promising avenue owing to their eco-friendliness, facile manufacturability, cost-effectiveness, low flammability, and commendable electrochemical performance. However, the intrinsic limitation in the rate capability of α-MnO₂ constitutes a significant impediment to its practical application. In this study, we introduce K-ion preintercalated nanorods (K-MnO₂-NR) with a diameter of approximately 10 nm as a cathode material for ZIBs. The synthesis of K-MnO₂-NR entails a facile one-step electrochemical participation method, whereby K-ion are electrochemically intercalated into the tunnel-structured α-MnO₂. The incorporation of K-ion serves a dual purpose of enhancing the electrical conductivity of manganese oxides and stabilizing the tunnel structure. Consequently, K-MnO₂-NR manifests exceptional rate capability, exhibiting a specific capacity of 222 mAh g⁻¹ at 2 A g⁻¹, coupled with outstanding cycling stability (with negligible capacity decay observed over 1450 cycles at 2 A g⁻¹). The facile and scalable synthesis process underscores its potential for large-scale production and eventual commercialization in pouch cells for energy storage applications.