LiNi0.8Mn0.1Co0. 1O2 Cathode Materials with High Physicochemical Stability By Addition of Binding Oxides

Abstract

Lithium-ion batteries are expanding beyond the power sources of conventional small-sized appliances, and as power sources for electric vehicles and hybrid electric vehicles. However, in order to expand them to the power source of medium and large-sized devices, it needs more improved energy density and stability than existing lithium ion batteries. As a cathode with high energy density, nickel-rich layered oxide in lithium nickel cobalt manganese trivalent oxide (LiNi1-2xMnxCoxO2, NMC) has attracted great attention. In particular, nickel-rich NMC material showed excellent initial discharge capacity compared with Ni low NMC, but the secondary particle intergranular fracture of aggregation occurs during the charging/discharging process, resulting in mechanical deterioration of the material. As a result, capacity decreased due to the increase of charge and mass transfer resistance of battery. In this study, the metal hydroxide is synthesized by co-precipitation with the addition of oxide materials, which acts as a binding agent in the primary particles. The addition of binding oxides improves the physical and chemical bonding of LiNi0.8Mn0.1Co0.1O2 (NMC811) Particles particles through the control at the precursor stage and it aims at securing the stability of the structure by preventing the crack formation, which is attributed to the mechanical stress of the primary particle phases during repeated cyclings. SEM and XRD analysis were performed to confirm the morphology, size and crystallinity of the powder and spherical particles with a layered structure (space group R-3m) were identified. In order to quantitatively analyze the local position and metal composition ratio of the binding oxide material and lithium in the particles, we studied the NMC811 and the binding oxide through EDS and ICP analysis. The electrochemical analysis was aimed to maintain the capacity over 90% at the lifetime characteristics (0.2 C, 100 times charge/discharge) and the energy density of the cathode material with the binding oxide. In addition, electrochemical characteristics and physical stability were evaluated by observing changes in real time surface characteristics by charging/discharging process using surface analysis such as in-line XPS.