One-step mild synthesis of δ-MnO2/Ti3C2T cathode for aqueous zinc-ion batteries

Manganese-based oxides are deemed to be prospective cathode materials for aqueous zinc-ion batteries (ZIBs). Nevertheless, their practical application was hampered by the slow zinc-ion diffusion dynamics and the instability of MnO2 structure. The δ-MnO2/MXene cathodes have been investigated to overcome the inherent defects of δ-MnO2 and significantly improve the performance of ZIBs. However, these δ-MnO2/MXene cathodes suffer from high-temperature, high-pressure, time-consuming or complicated production processes. To address these issues, δ-MnO2/Ti3C2Tx cathode was synthesized by a one-step in-situ growth strategy under mild conditions. The δ-MnO2/Ti3C2Tx cathode can take advantages of the large specific capacity of δ-MnO2 and the high conductivity of Ti3C2Tx nanosheets. Besides, the highly conductive Ti3C2Tx scaffolds efficaciously suppress the irreversible structural damage of δ-MnO2. Therefore, the ZIB assembled with the δ-MnO2/Ti3C2Tx cathode demonstrates significantly improved electrochemical behavior with a large specific capacity of 320.6 mAh g−1 at 0.1 A g−1, excellent rate capability of 153.0 mAh g−1 at 3.0 A g−1, high energy density of 440.0 Wh kg−1 at 136.6 W kg−1, and good cyclability with a capacity retention of 70.2 % after 1500 cycles, significantly outperforming the δ-MnO2 cathode. The findings of this study suggest that the δ-MnO2/Ti3C2Tx composite holds promise as a potential cathode for high-performance aqueous ZIBs.