Co-doped P3 type K0.5Mn1-xCoxO2 (x≤0.5) cathodes for long cycle life potassium ion battery

Potassium-ion batteries (PIBs) are a promising alternative to lithium-ion batteries for large energy storage systems due to their abundant potassium resources and low cost. However, the electrochemical properties of cathode materials, specifically the layered transition-metal oxides, hinder the practical application and development of PIBs. To overcome this challenge, further research is needed to improve the performance of cathode materials. This work presents the preparation of a series of K0.5Mn1-xCoxO2 (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) materials by doping with Co ions. As cathode materials, P3–K0.5Mn0.8Co0.2O2 shows better rate capacity and cycle performance, delivering a higher initial discharge capacity of 108.4 and 44 mAh g−1 at current rate of 20 and 200 mA g−1, respectively, compared to K0·5MnO2. Furthermore, the as-obtained P3–K0.5Mn0.8Co0.2O2 delivers a capacity of 62 mAh g−1 even at 400 mA g−1 and maintains the discharge capacity of 34.2 mAh g−1 after 200 cycles. The addition of suitable cobalt content enhances structural stability and ion transportation kinetics, ultimately improving the rate performance and cyclic stability during K+ insertion/extraction. These results could provide a new idea for the design and development of cathode materials for potassium ion batteries.