Electric Vehicles Go Further... Domestic Researchers Develop 'High-Capacity Long-Life' Battery Anode Material to Extend Driving Range

UNIST Specially Appointed Professor Jaepil Cho Develops New Concept 'Silicon Carbide-based' Mass Production Technology

Enables Suppression of Lifespan Degradation Due to Volume Expansion ‥ Published in Nature Energy

Schematic diagram of the synthesis process of the developed lithium-ion battery anode material.

[Asia Economy Yeongnam Reporting Headquarters Reporter Kim Yong-woo] A technology that significantly increases the driving range of electric vehicles is emerging, stirring the global next-generation automotive industry.

As domestic researchers have solved the durability issue, which has been a major obstacle to the commercialization of high-capacity anode materials, the world’s attention is focused on this technology.

The maximum distance driven on a single charge is proportional to the battery capacity installed. The anode material applied with this technology has a capacity up to three times larger than commercial graphite materials.

It also boasts excellent durability, as the material does not get damaged even after hundreds of charge-discharge cycles.

The research results were published on December 13 (4 p.m. London time) in Nature Energy, a world-renowned academic journal in the energy field.

The research team led by Distinguished Professor Cho Jae-pil of the Department of Energy Chemical Engineering at Ulsan National Institute of Science and Technology (UNIST) developed a synthesis technology that dramatically improves the durability of silicon-based high-capacity anode materials.

The anode material synthesized with this technology has silicon particle sizes that are small, and the silicon carbide surrounding the silicon protects it, enhancing durability.

Silicon has a theoretical capacity ten times greater than graphite, which is widely used in lithium-ion batteries, but the problem was durability.

Each time charging and discharging occur, the volume of silicon swells up to 360%. Repeated expansion and contraction easily cause structural damage.

There is also a risk of explosion due to gas generated during expansion, so the current limit for silicon-based materials mixed with graphite is known to be about 5% (around 400mAh/g).

To prevent rapid volume changes, silicon anode particles must be made as small as possible, but methods such as crushing bulk silicon have reached their limits.

Comparison by Anode Material.

Professor Cho’s team’s synthesis method can reduce particle size to less than 1 nm (one billionth of a meter).

The secret lies in suppressing nucleation growth during the vapor deposition process. The particles that make up the anode material grow from nuclei, which are seed stages where atoms attach and gradually enlarge to form a single crystal. By producing many nuclei while suppressing their growth, smaller particles can be made.

The co-corresponding author, Professor Kwak Sang-gyu’s team from the Department of Energy Chemical Engineering, theoretically verified this nucleation growth suppression effect through quantum mechanical calculations.

The silicon carbide surrounding the silicon particles not only improves durability but also increases battery capacity by preventing silicon from reacting with the battery electrolyte.

UNIST Professor Jae-Pil Cho.

When anode materials react with the electrolyte, battery capacity decreases, and a separate process to coat protective structures is required to prevent this.

When measuring the volume expansion rate of the synthesized anode material, it was only about 15%, similar to commercial graphite materials. Commercial graphite materials expand about 13% during charging.

Also, in commercial-level prismatic cell evaluations, after 2,800 charge-discharge cycles, 91% of the initial capacity was maintained. Until now, there have been no meaningful experimental results reporting battery cells with silicon-based anode materials having a charge-discharge lifespan exceeding 500 cycles.

Anode materials with such excellent properties are expected to be applied not only to electric vehicles (EVs) but also to high-capacity energy storage systems (ESS).

Co-first author Dr. Sung Jae-kyung explained, “Based on an in-depth understanding of the silicon particle (crystal) growth process, we were able to develop a new synthesis method that effectively solves the chronic problems of silicon anode materials.”

Dr. Seong Jaekyung, the first author.

Dr. Namhyung Kim, the first author.

Additionally, the method developed by the research team allows direct synthesis of silicon carbide on graphite, eliminating the need for a separate process to mix graphite and silicon carbide.

Generally, silicon-based materials are not used alone but mixed with graphite considering battery design, but silicon carbide (SiCx) can also be used independently.

Distinguished Professor Cho Jae-pil said, “Wet processes or mechanical crushing processes have been commonly used to produce silicon anode nanoparticles, but they have limitations in performance improvement as well as cost increase. The synthesis technology developed this time is a dry process for all steps, making mass production easy and expected to reduce production costs.”

This content was produced with the assistance of AI translation services.