Improving Ca-Ion Storage Dynamic and Stability by Interlayer Engineering and Mn-Dissolution Limitation Based on Robust MnO_2@PANI Hybrid Cathode

摘要

Rechargeable Ca-ion batteries (CIBs) have attracted great interest due topotentially high output voltage and abundant calcium resources. Amongvarious cathode materials, manganese oxides with high theoretical capacityand low cost are suitable as strong candidates for rechargeable CIBs.However, the dissolution of manganese and the strong electrostaticinteractions between Ca~(2+) and host materials result in inferior cycle stabilityand poor rate performance. Herein, a MnO_2-polyaniline (PANI) hybrid cathodewith both PANI intercalation and coating is developed to solve the aboveproblems. The intercalation of PANI can expand the interlayer spacing andeffectively buffer the local electrostatic interaction for facile Ca~(2+) diffusion.Meanwhile, the density functional theory (DFT) calculations prove that thePANI coating inhibits manganese dissolution by forming strong Mn-N bondsto enhance the structural integrity of MnO2. Benefitting from the above, theMnO_2-PANI (MnO2-P) cathode delivers high capacity (150 mAh g~(?1) at 0.1 Ag~(?1)), excellent rate performance (120 mAh g~(?1) at 1 A g~(?1)) and long-termcycling stability (5000 cycles). The organic-inorganic hybrid desig provides anew strategy for developing high performance CIBs cathode materials.