Development of High-Capacity, Long-Life Silicon Anode Material... "Improving Lithium-Ion Battery Performance"

A silicon anode material that increases the energy density of lithium-ion batteries with high capacity and long lifespan has been developed.

Battery materials are divided into four types: cathode materials, anode materials, separators, and electrolytes. Anode materials, a type of battery material, store lithium through a reduction reaction during charging and release lithium through an oxidation reaction during discharging. Among these, silicon anode materials are attracting attention as a material that can overcome and replace the limitations of conventional graphite-based anode materials.

Schematic diagram comparing the structure and electrochemical performance of silicon-based medium-entropy and high-entropy alloys, and the structural changes of high-entropy alloys during lithium-ion storage. Provided by the National Research Foundation of Korea.

The National Research Foundation of Korea announced on the 27th that Professor Ho-Seok Park’s research team at Sungkyunkwan University succeeded in developing a silicon-based high-entropy alloy material as a high-capacity, long-life lithium-ion battery anode material.

High-entropy alloys differ from conventional alloys, which add auxiliary elements to a main element, by mixing multiple elements at 5% or more (relatively equal ratios) without a main element, resulting in a material with a mixing entropy of 1.5R or higher. This alloy combination offers unique advantages and characteristics that enable the realization of various physical properties.

Recently, with the growth of the electric vehicle market, competition in battery technology has intensified. In this context, research to replace the capacity limit of graphite anodes (theoretical capacity 372mAh/g) with high-capacity silicon (theoretical capacity 4200mAh/g) has been actively conducted.

However, silicon materials have shown problems such as low electrical conductivity and volume expansion during repeated charge-discharge cycles, leading to long-term instability.

To address these issues, the research team developed a silicon-based high-entropy alloy material composed of various elemental compositions, imparting physical properties that are difficult to achieve with a single material, successfully preventing the performance degradation of silicon.

In particular, using a high-energy ball milling synthesis method, they minimized the synthesis process while incorporating the advantages of high-capacity silicon (Si), highly reactive phosphorus (P), germanium (Ge) with fast lithium-ion conductivity, and gallium (Ga), a liquid metal with self-healing properties, to develop the GaGeSiP3 material.

Ball milling is a grinding device consisting of a metal cylinder and balls; when the cylinder rotates, friction between the balls and the material, combined with centrifugal force, grinds or mixes the material into fine powder.

The developed GaGeSiP3 material showed a high rate capacity of 949mAh/g even at high current densities (a characteristic indicating how well capacity is maintained or deteriorates when charge-discharge speed is increased), and maintained a high capacity of 1121mAh/g even after 2000 charge-discharge cycles.

Professor Ho-Seok Park stated, “This research presents a solution to the silicon problem, a key material needed to increase the energy density of lithium-ion batteries, and it is significant in that it is the first time a high-entropy alloy material was realized with highly reactive phosphorus (P) atoms.”

Meanwhile, the research was conducted with support from the Leader Research Project promoted by the Ministry of Science and ICT and the National Research Foundation of Korea. The research results were also published in the April 16 issue of the international energy journal Energy & Environmental Science.

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