Improving Ca‐Ion Storage Dynamic and Stability by Interlayer Engineering and Mn‐Dissolution Limitation Based on Robust MnO₂@PANI Hybrid Cathode

Abstract Rechargeable Ca‐ion batteries (CIBs) have attracted great interest due to potentially high output voltage and abundant calcium resources. Among various cathode materials, manganese oxides with high theoretical capacity and low cost are suitable as strong candidates for rechargeable CIBs. However, the dissolution of manganese and the strong electrostatic interactions between Ca²⁺ and host materials result in inferior cycle stability and poor rate performance. Herein, a MnO₂‐polyaniline (PANI) hybrid cathode with both PANI intercalation and coating is developed to solve the above problems. The intercalation of PANI can expand the interlayer spacing and effectively buffer the local electrostatic interaction for facile Ca²⁺ diffusion. Meanwhile, the density functional theory (DFT) calculations prove that the PANI coating inhibits manganese dissolution by forming strong Mn‐N bonds to enhance the structural integrity of MnO₂. Benefitting from the above, the MnO₂‐PANI (MnO₂‐P) cathode delivers high capacity (150 mAh g⁻¹ at 0.1 A g⁻¹), excellent rate performance (120 mAh g⁻¹ at 1 A g⁻¹) and long‐term cycling stability (5000 cycles). The organic‐inorganic hybrid desig provides a new strategy for developing high performance CIBs cathode materials.