Elkem silicon in lithium-ion batteries

Li-ion batteries with silicon-based anodes are expected to be the winning technology for electric vehicles. Many companies, including raw material suppliers, fight for a position in this value chain. Elkem has a unique background for developing a high-quality silicon solution at competitive cost. 

Today, the challenge of using lithium ion batteries (LIB) is that they cannot fulfil the future capacity needed for, for example, electric vehicles. They are limited by the material properties of graphite, which restricts how many times the batteries can be charged. But by replacing the graphite with silicon we could solve this problem.

Elkem has carried out research on developing the optimal silicon material for batteries since 2010, and in 2015 we made good progress in increasing the numbers of charging cycles. The reason why introduction of silicon in lithium ion batteries is challenging and takes years of research and development is the expansion that occurs when silicon reacts with lithium during charging, and the corresponding contraction during dis-charging. To the extent these movements cause crack formation or destroy contact between anode material and current collector, capacity is lost, and the number of charging cycles is reduced. But if successful, using silicon in significantly increase the energy density and reduce the charging time, and results show that a battery with a silicon/graphite anode could do more than 1000 charge cycles.

On-going studies
On-going studies at research institutes and universities support Elkem in solving the expansion problems by modifying binders, electrolytes, cathodes, additives etc. The research activities done by researchers in Elkem are focused on micronization and chemistry. This means to establish a process for size reduction, to create a silicon quality with desired structure and purity, which produces repeatable particle sizes and size distributions in the low micron and sub-micron range both in bench- and industrial scale equipment.

“Green” feedstock
So far, the battery project has resulted in one patent and two patent applications. Elkem currently produces and supplies commercial amounts of speciality silicon, Silgrain®e-Si, at Elkem Bremanger to the first customers on a regular basis. Elkem’s unique production process gives Silgrain®e-Si a considerably lower environmental footprint than comparable silicon materials. The Dutch company “Smart Green Scans” reported in March 2017 results of the LCA analysis carried out at Bremanger and documented Silgrain®e-Si as a “green” feedstock to the LIB industry compared to competing raw materials.

This article was first published in Elkem's sustainability report in 2015.