Improvement of the high-temperature, high-voltage cycling performance of LiNi0.5Co0.2Mn0.3O2 cathode with TiO2 coating

Abstract The high-temperature cycling stability at a high cutoff voltage of LiNi 0.5 Co 0.2 Mn 0.3 O 2 was improved by TiO 2 coating. The mechanism of enhancement was elucidated by electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analyses. TiO 2 coating formed a uniform layer on the surface of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles without changing the crystal structure. Electrochemical tests indicated that TiO 2 coating can improve the lithium ion intercalation stability at 328 K and at a high cutoff voltage of 4.4 V. The 1.0% TiO 2 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 discharged 149.2 mAh g −1 after 100 cycles at 0.5 C , and maintained 92.1% of the initial discharge capacity. By contrast, the bare sample discharged only 87.7 mAh g −1 with 48.2% capacity retention. ICP-AES results proved that the TiO 2 coating layer can reduce the dissolution of transition metal ions from LiNi 0.5 Co 0.2 Mn 0.3 O 2 . EIS and XPS confirmed that the improved cycling stability can be attributed to the suppression of the reaction between cathode and electrolyte in lithium-ion batteries.