摘要
Searching appropriate cathode electrode materials for potential energy storage applications with relatively big sized potassium (K) ions is particularly difficult. Herein, δ-MnO 2 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 MnO 2 electrode exhibits an initial discharge capacity of 154 mAh/g at current rate of C/20 (15.4 mA/g) versus potassium in 1 M KPF 6 in EC:DEC electrolyte. As expected, the rate performances of MnO 2 in 1 M KPF 6 in EC:DEC electrolyte (108 mAh/g) are better than that of 1 M KPF 6 in PC electrolyte (93 mAh/g) at same rate of C/20. Not only δ-MnO 2 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 KPF 6 in EC:DEC electrolyte. Overall, MnO 2 exhibits improved electrochemical properties for K-ion batteries by improving charge storage mechanism associated with structural integrity, establishing MnO 2 as a potential candidate for commercialization in future.