LiNi0.5Co0.2Mn0.3O2 lithium-ion battery cathode material is considered to be one of the most promising cathode materials for development. The co-precipitation-freeze-drying method was used to add K+ to the materials to investigate the changes in the microstructure as well as the electrochemical properties of the materials. Specifically, K+-doped LiNi0.5Co0.2Mn0.3O2 cathode materials were successfully synthesized by the co-precipitation-freeze-drying method, and the prepared Li\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$_{{1 - x}}$$\end{document}KxNi0.5Co0.2Mn0.3O2 materials were well-distributed and exhibited excellent electrochemical properties. Providing an initial discharge capacity of 189.26 mA h g–1 capacity retention of 66.66%, 100 cycles of 2.5–4.8 V and a current density of 0.1 C. The good electrochemical performance of the material may be attributed to the increased lattice spacing of the material with the addition of K+, which enlarges the channels for lithium ion insertion and detachment, further accelerating its diffusion rate.