Tailoring porous three-dimensional (Co,Mn)(Co,Mn)₂O₄/PPy architecture towards high-performance cathode for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have gained extensive interest due to their cost-effective and safe nature. Nonetheless, the long-term performance of AZIBs is restricted by the conductivity and structural stability of cathode materials. Herein, the porous (Co,Mn)(Co,Mn)₂O₄/PPy (CMO@PPy) core–shell microspheres have been favorably synthesized using a facile solvothermal method followed by a self-polymerization process. The porous structure endows CMO@PPy with more active sites which can facilitate ion and electrolyte diffusion. And PPy as coating layers not only improve the conductivity but also buffer the structural strain of cathode material, as well as inhibit the dissolution of Mn²⁺. Additionally, the core–shell nanostructure can effectively release the volume expansion of cathode during the cycling process. Benefitting from the unique structure, the CMO@PPy cathode delivers a high capacity of 305.2 mAh g⁻¹ at 0.1 A g⁻¹ and superior long-term cycling stability (90.8 mAh g⁻¹ at 1 A g⁻¹ after 1000 cycles with a decay of only 0.037% per cycle). Also, the enhanced electrochemical kinetic of CMO@PPy is evaluated by Galvanostatic intermittent titration technique. Additionally, the assembled flexible ZIBs demonstrate stable electrochemical properties at different bending states, indicating their potential practical applications.