Boosting aqueous Zn-ion battery performance with Co2+-doped δ-MnO2/Ti3C2Tx cathode through enhanced ion transport and structural stabilization

Introduced Co 2+ increases the structural stability of δ-MnO 2 and enlarges the interlayer spacing, promoting ion diffusion. • δ-MnO 2 @Co/TCT further improves the electrical conductivity, ameliorates the agglomeration problem and increases the electrochemical reaction active area. • Synergistic improvement of electrochemical performance through the strategy of ion doping and introduction of conductive materials, Zn//δ-MnO 2 @Co/TCT full cell with 1000 stable cycles at 1.5 A g -1 . δ-MnO 2 is considered a highly promising cathode material for aqueous zinc-ion batteries (AZIBs). However, its practical application is hindered by two critical issues: delayed transport kinetics and insufficient structural stability. Therefore, a synergistic strategy involving Co 2+ doping and composite coating with Ti 3 C 2 T x MXene (TCT) nanosheets was designed and implemented to achieve effective doping of the δ-MnO 2 lattice with Co and to ensure uniform loading of the active component onto the TCT substrate surface, ultimately leading to the successful fabrication of the δ-MnO 2 @Co/TCT composite material. First, the incorporation of Co 2+ as interlayer pillars effectively widens the interlayer spacing of δ-MnO 2 , thereby enhancing its structural stability and enabling faster ion embedding/de-embedding. Second, the TCT conductive substrate effectively mitigates the agglomeration of δ-MnO₂@Co, significantly increasing the electrochemical reaction area. Benefiting from the unique composite structure design, the Zn//δ-MnO 2 @Co/TCT full cell exhibits significantly optimized electrochemical performance. The assembled cell delivers a high specific capacity of 239.5 mAh g −1 at 0.5 A g −1 , and maintains outstanding cycling stability over 1000 cycles at 1.5 A g −1 . Result indicates that comprehensive performance of cathode materials can be effectively enhanced by multilevel structural synergistic design, providing a feasible technological pathway for development of high-performance AZIBs.