KxCu1−xO1−γ (0 ≤ x ≤ 0.12) and K0.08Cu0.92O1−γ anode materials are synthesized via a simple ethylene glycol assisted sol-gel method and characterized by X-ray diffraction, Scanning Electron Microscopy, High-resolution/Transmission Electron Microscopy, Energy Dispersive Spectroscopy and Select Area Electron Diffraction. The introduction of potassium element improves the electro-chemical performance of CuO greatly, especially for x = 0.08. After Ag coating, K0.08Cu0.92O1−γ@Ag anode displays superior electro-chemical performance with excellent reversible capacity, cyclic performance and rate capability. It delivers a capacity of 804.3 mA h g−1 even at the 50th cycle. The role played by the K element doping and Ag coating are fully discussed.