Optimization of LiMnFePO4 cathode materials via dual metal coating: A comparative study of copper and nickel surface modification

Abstract

With the rapid development of the global new energy vehicle market, there is an urgent demand for battery materials with high performance, enhanced safety, and low cost. Lithium manganese iron phosphate (LMFP), as an upgraded version of lithium iron phosphate (LFP), combines the safety and cost-effectiveness of LFP while significantly improving energy density and low-temperature performance, making it a strong contender for next-generation power battery materials. This study focuses on the development of double coating of copper and nickel is carried out on the commercial lithium iron manganese phosphate cathode material through an optimized chemical co-precipitation method, and its surface modification was systematically investigated through a combination of XRD, SEM, and electrochemical performance tests. A comprehensive analysis was conducted to evaluate the effects of varying coating concentrations and mono/dual metal coating configurations on the electrochemical performance. The experimental results demonstrated that the LMFP/CuNi composite with a Cu/Ni ratio of 6:4 exhibited optimal electrochemical performance. The synthesized sample exhibited a discharge capacity of 153.9 mAh·g⁻¹ at 0.2C rate, with remarkable capacity retention rates of 95.5 %, 94.0 %, and 89.2 % after 100 cycles at 0.5 C, 1 C, and 2 C rates, respectively. Comparative studies between single-coated and dual-coated LMFP materials revealed superior performance in dual-coated systems. The LMFP/CN1 dual-coated sample maintained 88.1 % capacity retention after 200 cycles at 1 C rate. The exchange current density for this optimized material reached 4.58 × 10⁻⁴ A cm⁻², indicating enhanced electrochemical kinetics. These findings suggest that the Cu/Ni ratio optimization combined with dual-coating strategy significantly improves both the cycling stability and rate capability of LMFP-based cathode materials, demonstrating promising potential for high-performance lithium-ion battery applications.