Structure and electrochemical performance of TiO2-coated LiNi0.80Co0.15Al0.05O2 cathode material

• TiO2 is coated on surface of LiNi0.8Co0.15Al0.05O2 via chemical deposition.
• TiO2-coated LiNi0.80Co0.15Al0.05O2 exhibits enhanced electrochemical performance.
• EIS is used to elucidate the effect of the TiO2 coating layer.

Layered Ni-rich LiNi0.8Co0.15Al0.05O2 cathode material is successfully modified by TiO2 coating. X-ray diffraction (XRD) results show that the crystal structure of LiNi0.80Co0.15Al0.05O2 is not changed by TiO2 coating, and no impurity phase is observed. The morphologies of the samples are characterized by scanning electron microscope (SEM) analysis. Compared with pristine sample, the TiO2-coated sample shows no change on morphology. However, a thin TiO2 coating layer can be observed through transmission electron microscope (TEM) analysis. Besides, energy dispersive spectrometer (EDS) elemental mappings results confirm that the TiO2 is uniformly coated on the host material. The electrochemical characterizations demonstrate the capacity retention and stability of the TiO2-coated sample are much improved than that of pristine one. At 25 °C, the discharge capacity loss of TiO2-coated sample after 100 cycles at 1 C is 36.3%. However, the pristine sample only delivers 80.7 mA h g−1, or only 47.5% retention. The capacity improvement is related to the fact that the highly distributed TiO2 near the surface diminishes the side reactions between the cathode and electrolyte.