In-situ growth of co-intercalated MnO2 on 3D lignin-based carbon nanoflowers endows high-performance aqueous zinc-ion batteries cathode.

The electrochemical kinetics, conductivity, and lifespan of MnO2 are significant challenges that impede its commercialization as a cathode material for aqueous zinc-ion batteries (AZIBs). In this study, carbon nanoflowers (NFCs) were prepared from lignin as a carbon source, and the dissolution behaviour of MnO2 during cycling was inhibited by uniformly loading nanoflower-like δ-MnO2 (MnO2@NFC) on NFCs in situ. Additionally, Co-intercalated δ-MnO2/lignin-based carbon nanoflowers (Co-MnO2@NFC) were prepared and used as the cathode for rechargeable AZIBs. The initial discharge capacity of the AZIBs using Co-MnO2@NFC as the cathode material is as high as 340 mAh·g-1 at a specific current density of 0.1 A·g-1, and the capacity retention rate reaches 88.1 % after 1000 cycles at 1.0 A·g-1. Co-MnO2@NFC exhibits excellent conductivity compared to δ-MnO2 and MnO2@NFC. Through electrochemical analysis and ex-situ characterization, the energy storage mechanism of Co-MnO2@NFC is identified as H+/Zn2+ co-insertion/extraction. This work enhances the stability of MnO2 by loading it onto NFC carriers. It improves the specific capacity of the material by intercalating Co ion, providing a new approach for the controllable design of cathodes for AZIBs.