The surface of LiNi 1/3 Co 1/3 Mn 1/3 O 2 particles were modified by AlPO 4 . Influences of heat-treatment on coating were studied by X-ray diffraction (XRD) and thermal analysis. Electrochemical tests and electrochemical impedance spectroscopy (EIS) were conducted. The results show that AlPO 4 can react with LiNi 1/3 Co 1/3 Mn 1/3 O 2 and an aluminum-containing-spinel phase of M 0 1 M 2 O 4 (M ¼ Ni, Co, Mn, M 0 ¼ Al) is formed at above 700 C. The high surface content of aluminum is in favor of forming a stable solid electrolyte film (SEI) on the surface of LiNi 1/3 Co 1/3 Mn 1/3 O 2 during the first-two-charge-discharge processes. NO 3 À from the coating process may have reacted with LiNi 1/3 Co 1/3 Mn 1/3 O 2 . The resultant decompose at the temperature of above 400 C. Existence of NO 3 À in the cathode is harmful to its electrochemical properties. The LiNi 1/3 Co 1/3 Mn 1/3 O 2 coated with 1 wt% AlPO 4 delivers a high discharge capacity and shows excellent capacity retention at 55 C/0.5 C.

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