El Houcine El Maataouy¹, Nassima Jaghar¹, Rachid Oubaki¹, Majid El Kassaoui², Ghizlane El Omari¹, Abdlewahed Chari¹, Mohamed Makha¹, Mohamed Aqil¹, Catalin Negrirac, Jones Alami¹, Omar Mounkachi^1,2, Mouad Dahbi^1
1Mohammed VI Polytechnic University, Benguerir, Morocco
²Mohammed V University, Rabat, Morocco
³National Institute of Materials Physics, Bucharest-Magurele, Romania
This study investigates TiOx-coated LiNiO_₂ (LNO) electrodes prepared via high-impulse-power magnetron sputtering (HiPIMS) as a strategy to stabilize the cathode interface and mitigate Ni-ion dissolution. A thin TiO_x layer, sputtered with a thickness of ~10 nm, was found to enhance the electrochemical performance of LNO electrodes. Half-cell electrochemical characterization demonstrated significant improvements in capacity retention over 120 cycles at 25°C. Moreover, the rate capability of the coated electrodes was markedly improved, with a 79% higher capacity at 5 C compared to pristine electrodes. These enhancements are attributed to the high Li^⁺ diffusivity of the anatase TiO_₂ surface layer, as well as the preservation of bulk electronic conductivity in the LNO cathode. The cycling stability benefits are further linked to reduced impedance growth during cycling. Additionally, glow discharge optical emission spectroscopy (GD-OES) analysis indicated that TiO₂ coating effectively retards Ni-ion dissolution. The uniformity of the TiO_x coating was evaluated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), revealing a quantitative correlation between Ti content and sputtering time. The interface, LiNiO_₂/TiO_₂ particle was investigated using high-resolution electron microscopy (HTEM) and density functional theory (DFT) calculations, which confirmed improved structural integrity and stability.