Li x Mn2O4 (LMO) and Li x Mn2O4–0.5ZrO2 (LMZO) thin films have been fabricated by radio-frequency (rf) sputtering deposition combined with conventional annealing method. The structures and surface morphology of thin films are characterized by X-ray diffraction, transmission electron microscopy, selected area electron diffraction and scanning electron microscopy techniques. It is shown that the addition of mass quantity of ZrO2 in LMZO can control the grain growth of nano-crystalline LMO. The electrochemical performances of all-solid-state thin film lithium batteries (TFBs) based on these thin films as cathodes are examined by cyclic voltammetry (CV), galvanostatic mode and alternate-current impedance measurements. Our results demonstrated that the addition of electrochemically inactive ZrO2 could significantly overcome the disadvantage of two distinct plateaus in 3 and 4V regions. LMZO is expected to become a promising cathode material for future TFBs.