Electrochemical Performance of MoB/Si3N4 Heterojunction as a Potential Anode Material for Li Ion Batteries.

Abstract

In response to the current policy of high storage capacity, two-dimensional (2D) materials have revealed promising prospects as high-performance electrode materials. MoB, as a type of such material, is widely regarded as an anode candidate for Li-ion batteries due to its large specific surface area and abundant ion diffusion channels; the long-term cycling stability, however, is poor owing to material pulverization during the cycle. Therefore, MoB/Si₃N₄ heterojunction in this work is proposed as an anode material, with Si₃N₄ acting as a skeleton, maintaining the stability of the structure, while retaining the high energy storage properties of MoB as well. In addition, a certain built-in electric field is formed between them, which can play a role in regulating charge transfer, improving the ion transport channel, and accelerating the migration rate. Herein, the structural, electronic, and electrochemical properties are systematically investigated by first-principles calculations; the final results indicate that the heterojunction anode material does indeed have built-in electric fields, which promote the anode material to possess excellent electrical conductivity and outstanding electrochemical property. Meanwhile, the introduction of vacancy defects can bolster the diffusion kinetic performance of ion transport and greatly reduce the diffusion energy barrier of Li ions, which is conducive to the realization of rapid charge and discharge for the Li ion battery. Based on the synergistic effect of two single-component materials, the synthesized anode material displays a high theoretical capacity of 461 mAh/g, and the calculated open-circuit voltage is 0.66 V, within the range of the negative electrode criterion of 0-1 V, which can effectively play a role in preventing the formation of Li dendrites; these properties are comparable to other 2D anode materials as well. Given these intriguing properties, the MoB/Si₃N₄ heterojunction is an exceptional candidate for advanced LIB high-performance anode materials.