High-rate LiNi_0.5Mn_1.5O₄ cathode materials for Li-ion batteries by the strategy of multi-ion co-doping

LiNi_0.5Mn_1.5O₄ (LNMO) is a high-profile cathode material for lithium-ion batteries with high voltage and high specific energy. However, its practical application is severely hindered by the dissolution of Mn, primarily induced by the Jahn-Teller effect, which leads to significant capacity degradation, especially under high current densities. In this research, LiNi_0.5-7/3xCu_xAl_xMn_1.5-7/3xTi_xV_xO₄(x = 0, 0.5 %, 1 %, 3 %) was synthesized via a sol–gel method employing a multivalent ion co-doping strategy, denoted as CATV. X-ray diffraction analyses that the increase in the (311)/(400) peak ratio of CATV-1 % indicates a higher concentration of Mn³⁺, which enhances the structural disorder of the material, thereby improving its electronic conductivity. By improving the ratio of the (110) plane, which is perpendicular to the lithium-ion diffusion pathway, the lithium-ion diffusion coefficient was enhanced by three orders of magnitude. Furthermore, the Mn dissolution issue originating from the (111) plane was mitigated which shows in XRF that the Mn content deposited on the negative lithium sheet was reduced by 50 %. Specifically, it delivered specific capacity of 136.2 mAh·g⁻¹ at 0.1C and maintained 81.74 % of its capacity after 300 cycles at 1C. Under 20C charge–discharge condition, it reached 108 mAh·g⁻¹, doubling that of the undoped sample. These findings provide new possibilities for the commercial application of CATV materials.