Lithium intercalation in the surface region of an LiNi1/3Mn1/3Co1/3O2 cathode through different crystal planes

Abstract

Epitaxial LiNi_1/3Co_1/3Mn_1/3O₂ film electrodes with orientations of (104), (1−18) and (003) were fabricated on SrRuO₃/SrTiO₃ by pulsed laser deposition. The films have a thickness of 23.8 to 25.0 nm and a flat surface with a roughness of approximately 2 nm, which offered a model system for clarifying the reaction plane dependencies of lithium intercalation at the LiNi_1/3Co_1/3Mn_1/3O₂ surface. All reaction planes delivered reversible lithium intercalation for electrochemical charging–discharging between 3.0 V and 4.3 V (vs. Li/Li⁺). The (104) surface exhibited reversible behavior at a higher operation voltage between 3.0 V and 4.5 V, but the (1−18) and (003) planes showed fading of the discharge capacity and average discharge voltage. The anisotropic stability of the surface region indicates the importance of crystallographic facet control for the development of an LiNi_1/3Co_1/3Mn_1/3O₂ cathode with high cycle stability.