Hexagonal d-MnO2 nanoplates as efficient cathode material for potassium-ion batteries

Searching appropriate cathode electrode materials for potential energy storage applications with relatively big sized potassium (K) ions is particularly difficult. Herein, delta-MnO2 with hierarchical hexagonal nanoplate structure has been synthesized to combine together to form the material with vast space for large ions to transport and store. The battery performance as cathode material associated with K-ions, investigated by constant charge -discharge studies, reveals that the MnO2 electrode exhibits an initial discharge capacity of 154 mAh/g at cur-rent rate of C/20 (15.4 mA/g) versus potassium in 1 M KPF6 in EC:DEC electrolyte. As expected, the rate per-formances of MnO2 in 1 M KPF6 in EC:DEC electrolyte (108 mAh/g) are better than that of 1 M KPF6 in PC electrolyte (93 mAh/g) at same rate of C/20. Not only delta-MnO2 delivers stable capacity up to 200 cycles at C/10 rate (30.8 mA/g) but coulombic efficiency of nearly 100% is sustained for repetitive cycling in 1 M KPF6 in EC: DEC electrolyte. Overall, MnO2 exhibits improved electrochemical properties for K-ion batteries by improving charge storage mechanism associated with structural integrity, establishing MnO2 as a potential candidate for commercialization in future.

Automated summary

The hierarchical hexagonal nanoplate structure of delta-MnO2 provides ample space for large ions transport and storage. The MnO2 electrode exhibits good battery performance as a cathode material for potassium ions, with higher rate performance in EC:DEC electrolyte than in PC electrolyte. The stability and high coulombic efficiency of MnO2 make it a potential candidate for commercialization in future K-ion batteries.