A one-pot surface coating process employing a bifunctional hybrid solution for high-Ni cathode materials for lithium ion batteries

A uniform surface coating and control over residual Li on the surface of high-Ni layered transition metal oxides is crucial for development of highly reliable and high-performance cathode materials for lithium ion batteries (LIBs). To suppress undesirable side reactions at the surface of high-Ni layered transition metal oxides, we propose a one-pot TiO2 surface coating process using a bifunctional hybrid solution. We demonstrate that the uniformity and thickness of a TiO2 coating layer can be controlled, and residual Li can be simultaneously reduced during the surface coating process. Structural and electrochemical characterizations support the utilization of an essential bifunctional hybrid solution composed of titanium (IV) isopropoxide (TTIP) in isopropyl alcohol (IPA) and tetrabutyl-ammonium hydroxide (TBAOH) in water for introducing a uniform TiO2 coating layer and eliminating undesirable Li residues on the surface without yielding significant structural degradation. Our approach provides a practical guide to develop advanced cathode materials and simplify the synthetic process for mass production. A one-pot TiO2 surface coating process using a bifunctional hybrid solution composed of titanium (IV) isopropoxide (TTIP) in isopropyl alcohol (IPA) and tetrabutyl-ammonium hydroxide (TBAOH) in water for introducing a uniform TiO2 coating layer and eliminating undesirable Li residues on the surface without yielding significant structural degradation. [Display omitted] •A one-pot TiO2 surface coating process using a bifunctional hybrid solution is proposed.•A bifunctional hybrid solution is essential for introducing a uniform TiO2 coating and eliminating undesirable Li residues.•TiO2 coated NCM811 exhibits a high reversible capacity of more than 200 mAh g−1 and stable cycle performance.