Cycling stability of 5 V spinel LiMn1.5Ni0.5O4 (LMNO) is improved by surface modification with FePO4 through a chemical deposition method. The pristine, 0.5 wt.%, 1 wt.% and 3 wt.% FePO4-coated LMNO are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and field emission scanning electron microscopy. It is found that the coating process is in favor of the disorder–order phase transition. The investigation on their cycling performance demonstrates that 1 wt.% FePO4-modified LMNO cathode exhibits the best cycling performance, with the capacity retention ratio of 99.3% after 50 cycles, much better than that of the pristine LMNO (only 79%). Electrochemical impedance spectroscopy is applied to explain the galvanostatic results. The enhanced cycling performance of the surface-modified samples can be attributed to the decreasing contact area between the electrode and electrolyte and the suppression of undesirable thick SEI (solid electrolyte interfacial) layer.