Interconnected MnCO3 nanostructures anchored on carbon fibers with enhanced potassium storage performance

Potassium-ion batteries (PIBs) have gained considerable attention in the past decade because of the rich potassium reserves in our planet. However, the development of anode materials is still a major challenge because of the hard reaction kinetics and poor cycling stability in the insertion/extraction process. Herein, we report interconnected MnCO₃ nanostructures anchored on carbon fibers (MnCO₃/CF) composites as anode for PIBs. The MnCO₃/CF can be directly used as anode on PIBs, avoiding the addition of polyvinylidene fluoride (PVDF) binders and the complicated slurry coating onto copper process. The nanosized MnCO₃ nanostructures are interconnected with each other, which can provide short ions diffusion length during the charge/discharge process. The MnCO₃ nanostructures are firmly anchored on the surface of CF through C–Mn bonds, ensuring cycling stability. Also, the CF with good electronic conductivity guarantees fast electrons transportation in MnCO₃/CF system. Benefiting from the advantageous features mentioned earlier, the MnCO₃/CF anode behaves enhanced potassium storage performance compared with that of pure MnCO₃ anode. The MnCO₃/CF anode delivers a high capacity of 462 mAh/g at 50 mA/g after 100 cycles, whereas the capacity of pure MnCO₃ anode is only 134 mAh/g at 50 mA/g after 80 cycles. This work demonstrates the prospect of metal carbonate as anode materials for PIBs and provides a useful strategy to design advanced anode materials for PIBs.