Japan JAIST develops new β-SiC nanoparticle-based negative electrode material for lithium-ion batteries

Lithium-ion batteries (LIBs) have become the cornerstone of portable electronics, electric vehicles , and the alternative energy economy due to their long life, good energy storage performance, high energy density, and high operating voltage . Improving electrode materials is the most critical and feasible method to improve the electrochemical performance of LIBs. At present, electrode material research has gone beyond the traditional carbon-based graphite anode and has developed towards alternative materials such as transition metal oxides, tin, and silicon-based materials.

(Image source: JAIST)

Silicon is second only to oxygen in abundance in the Earth's crust. This promising negative electrode material has attracted widespread attention due to its electronic properties, especially its high capacity. However, the material undergoes large volume changes during operation, which affects its stability, structural integrity and electrical performance, leading to problems such as particle breakage or current collector peeling during charge and discharge. These problems have hindered the entry of silicon-based materials into the commercial lithium-ion battery industry.

According to foreign media reports, in order to solve these problems, researchers Ravi Nandan, doctoral student Noriyuki Takamori, technical expert Koichi Higashimine, senior lecturer Rajashekar Badam and Professor Noriyoshi Matsumi from the Japan Advanced Institute of Science and Technology in Hokuriku, Japan, sought inspiration from sphalerite. The team proposed a complex, instrument-free, and novel strategy to create unique sphalerite silicon carbide nanoparticles at relatively low temperatures.

The three-dimensional intermetallic compound structure in the zinc blende system can easily accommodate lithium ions in its interstitial positions. When lithium ions shuttle between the host materials, the volume of this structure changes very little, thus achieving better life and reversibility. The silicon-based counterpart of zinc blende-type materials is β-silicon carbide (SiC). Some previous studies have reported the technology of synthesizing β-SiC composites as negative electrode materials, but most of them involve complicated procedures and instruments.

The team designed a two-step synthesis process to prepare β-SiC-based anode materials for lithium-ion batteries. The first step is to form silicon nanoparticles in a polydopamine matrix; the second step is to convert them into a special variant of β-SiC nanoparticles in a nitrogen-doped carbon matrix. Interestingly, this conversion process requires lower temperatures than traditional methods, as low as 600 degrees Celsius.

The obtained material was then used in a negative electrode half-cell configuration and electrochemical screening was performed. The results showed that the battery had a high current density, rated capacity, and good reversible lithium-ion storage compatibility. In addition, it also showed a high capacity retention rate, maintaining about 94% of the capacity after 300 charge and discharge cycles, and the discharge capacity remained at 1195 mAhg-1.

This synthesized material can be successfully used as a negative electrode, and when combined with a commercial LiCoO2 positive electrode, the full cell formed in this way demonstrates the great application potential of β-SiC in commercial LiB systems. The simple preparation technology proposed in this study opens the door to numerous studies on β-SiC and LiB. Professor Matsumi concluded: "Global carbon emissions are increasing due to the use of fossil fuels in transportation. This low-cost manufacturing method of β-SiC negative electrode material can be used to develop high-energy density batteries to promote the development of a cleaner and greener electric vehicle industry. In fact, its application is expected to expand to other means of transportation such as trains, airplanes and ships."