Japanese research institute develops all-solid-state battery electrode material with excellent performance

A new study led by researchers at the National Institute for Materials Science and Engineering in Japan shows that in a solid electrolyte, a silicon anode consisting only of industrial silicon nanoparticles prepared by a spray deposition method has excellent electrode performance. This method is a cost-effective and atmospheric technology, so the researchers' results suggest that low-cost and large-scale production of high-capacity anodes for all-solid-state lithium batteries will be possible in the near future .

The theoretical capacity of silicon can reach 4200 mAh/g, which is 10 times greater than the capacity of graphite, which is commonly used as an active negative electrode material in commercial lithium batteries . Replacing traditional graphite with silicon can greatly extend the driving range of electric vehicles per charge, but silicon undergoes huge capacity changes during lithiation and delithiation, that is, during the charging and discharging process, which hinders its practical application in batteries.

In conventional liquid electrolytes, polymer binders are needed to hold the active material particles in the electrode together and maintain their adhesion to the metal surface. The continuous capacity change of silicon leads to particle separation, loss of active material, and finally continuous capacity loss. In solid-state batteries, the active material is placed between two solid-state components, namely the solid electrolyte separator and the metal current collector. The actual areal capacity of sputter-deposited pure silicon films exceeds 2.2 mAh/cm2, showing good cycle stability and high-rate discharge capability in solid electrolytes. Despite this, the cost-effectiveness and industrial scalability of all-solid-state lithium battery anodes remain a huge challenge.

Image source: National Institute for Materials Science and Engineering, Japan

Researchers from the National Institute for Materials Research team in Japan have adopted an alternative synthesis approach to obtain high-performance anodes for all-solid-state lithium batteries from commercial silicon nanoparticles. They found that the nanoparticles exhibit a unique phenomenon in solid-state batteries: upon lithiation, they undergo volume expansion, structural compaction, and pronounced coalescence to form a continuous film in the confined space between the solid electrolyte separator layer and the metal current collector, similar to films prepared by evaporation. As a result, the anode composed of nanoparticles prepared by vapor deposition exhibits excellent electrode performance, which was previously only observed for thin-film electrodes deposited by sputtering. Spray deposition is a cost-effective atmospheric technique that can be used for large-scale production.

Therefore, these findings will pave the way for low-cost and large-scale production of high-capacity anodes for all-solid-state lithium batteries.