Preparation and Potassium Ions Storage Properties of P3-Type K0.5MnO2 as an Advanced Layered Cathode Material for Potassium-Ion Batteries

Purposes K-ion batteries (KIBs) have attracted considerable attention as a potential alternative to Li-ion batteries because of their low cost and high energy density. However, the development of KIBs has been severely limited by the lack of cathodes with high specific capacity and good cycle performance. Methods In this research, P3-type K0.5MnO2 as a new cathode material for KIBs was prepared through hydrothermal method, sol-gel method, and oxalate co-precipitation method, separately. Conclustions It is shown that K0.5MnO2 synthesized through the hydrothermal precursor method (denoted as H-K0.5MnO2) has a rough surface and more internal pores, which are beneficial to electron transfer and can provide more active sites. At a specific current of 20 mA/g, H-K0.5MnO2 electrode can achieve the highest first discharge specific capacity of 85 mAh/g. XRD and EIS results of the H-K0.5MnO2 electrodes after 60 cycles demonstrate that H-K0.5MnO2 still maintains the most stable structure and has the smallest charge transfer resistance, leading to a desirable capacity retention. The potassium-ions storage properties indicate that the pseudo-capacitance accounts for the highest proportion in H-K0.5MnO2 at a high rate, enabling fast reversible charge-discharge.