Influences of lanthanum doping on electrochemical performances of Co-free high voltage LiNi0.5Mn1.5O4 cathode materials for Li-ion batteries

Abstract

LiNi_0.5Mn_1.5O₄ (LNMO) stands out as a highly promising cathode material for next-generation lithium-ion batteries, offering notable benefits such as a high operational voltage, cobalt-free composition, and a high theoretical specific capacity. However, LNMO cathode materials still have several drawbacks, particularly concerning structural stability and transition metal dissolution which result in poor capacity retention. In this work, we introduced a small amount of La as dopant in LNMO cathode materials. The incorporation of La³⁺ can reduce the formation of Mn³⁺ within the structure, thereby mitigating transition metal dissolution. Furthermore, La³⁺ doping influences the crystal properties, offering two advantages. Firstly, the presence of La³⁺ in the 16d sites enhances structural stability. Secondly, it facilitates easier Li⁺ ion diffusion, thereby ensuring high cycle stability and rate capability. The optimized La-doped LNMO sample demonstrated excellent performance, retaining 90.54% of its capacity after 200 cycles at 0.5C within a voltage range of 3–4.8 V and achieving a high-rate capability of 78.3% at 5C. The optimum La doping provided a minimum capacity loss and voltage fading, indicating the beneficial effect of La dopant for providing a stable structure and preventing transition metal dissolution. This strategy offers a promising route toward the development of high-performance, cobalt-free, high-voltage cathodes for next-generation lithium-ion batteries.

Graphical Abstract