Abstract: In order to investigate the effect of Ni doping on the performance of the cathode material, a K_0.5Ni_0.33Mn_0.67O₂ cathode material for potassium K-ion batteries was prepared by a two-step method of coprecipitation and solid-phase sintering. The phase and morphology of the material were analyzed by XRD and SEM. The electrochemical characteristics and kinetics of K_0.5Ni_0.33Mn_0.67O₂ were investigated by galvanostatic charge-discharge test and cyclic voltammetry (CV) performance. The results show that the high crystallized K_0.5Ni_0.33Mn_0.67O₂ delivers good cycle stability and the maximum discharge capacity at 10, 20, 50, 100, 200, 500 mA/g are 81.20, 64.18, 59.68, 48.42, 37.64 mA·h/g, respectively, indicating good rate capability.