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.