Amping up Li-ion battery performance with black glass

A group of researchers from the Japan Advanced Institute of Science and Technology (JAIST), led by Professor Noriyoshi Matsumi, have developed an electrode material inspired by the properties of silicon grafted with black glasses.

Silicon-based negative electrode materials have excellent energy capacity, making them suitable for use in lithium-ion batteries. However, their practical application faces challenges including the lack of mechanical strength and rapid capacity fading. The researchers from JAIST aim to alleviate this problem through the use of anodes prepared from this silicon microparticle-based material, which were highly resilient with excellent capacity retention.

Silicon is reportedly the most abundant element on earth, making up 27.7% of the earth’s crust. Apart from its ability to create sandy beaches and clear glasses, silicon also holds the potential to make highly efficient metal-ion batteries. In a world where alternative energy storage devices like lithium-ion batteries are gaining momentum, there is a need to harness the specific energy capacity of silicon as an electrode material. The commercial application of silicon-based electrode materials is often hindered due to two reasons: the lack of mechanical stability arising from uncontrolled volume expansion upon lithiation (the process of combining with a lithium-ion) and the rapid energy fading caused by the formation of unstable solid-electrode interface (SEI) formation.

Over the years, scientists have developed various advanced silicon-based negative electrodes or anode materials to overcome the aforementioned problems. Among the most prominent are silicon nanomaterials. However, silicon nanomaterials come with certain demerits, such as a large demand and supply gap, difficult and expensive synthesis process, and a threat of fast battery dry-up. Now, the researchers from JAIST, led by Professor Noriyoshi Matsumi, have proposed a solution to these issues plaguing silicon micronparticles (SiMP).

In the study published in the Journal of Materials Chemistry A, the researchers reported a holistic approach to synthesising novel highly resilient SiMPs consisting of black glasses (silicon oxycarbide) grafted silicon as anode material for lithium-ion batteries. The research team included Ravi Nandan, a research fellow, Noriyuki Takamori, a doctoral course student, Koichi Higashimine, a technical Specialist, and Dr Rajashekar Badam, a former Senior Lecturer at JAIST.

“Silicon nanoparticles might provide increased effective surface area but that comes with its own drawbacks like increased consumption of electrolyte as well as poor initial coulombic efficiency after a few cycles of charging and discharging. SiMPs are the most appropriate, low-cost and easily available alternatives, especially when combined with materials that have exceptional structural properties, such as silicon oxycarbide black glasses. Our material is not only high performing but also conducive to scale opportunities,” Matsumi said.

The researchers designed a core-shell type material where the core was made up of SiMP coated in a layer of carbon. The silicon oxycarbide black glasses were then grafted on as the shell layer. The prepared materials were then used in an anodic half-cell configuration to test their ability to reversibly store lithium under different potential windows. This screening showed that the material has great lithium diffusion ability, reduced internal resistance and overall volumetric expansion. The superior electrochemical properties of this new material were established by the 99.4% retention of energy capacity after 775 cycles of charging and discharging. In addition to the superlative energy storage abilities, the material also exhibited great mechanical stability throughout the testing process.

The results indicated the superiority of the new SiMP-based active anode materials. These materials have now opened up pathways for the application of silicon in next-generation secondary lithium-ion batteries. The upscaling ability of this synthesis process can help bridge the gap between laboratory research and industrial applications in the field of energy storage. This is particularly important for producing low-cost electric vehicles, which can appreciably reduce carbon emissions.

“Our methodology offers an effective avenue for the development of high-performance anode materials for energy-efficient lithium-ion batteries, which is an essential building block towards creating a sustainable and low-carbon tomorrow,” said Matsumi, when asked about the significant application of the study.

Image credit: iStock.com/Just_Super