Rechargeable silicon battery for renewable energy storage

Rechargeable Silicon Battery - conceptual illustration.
Rechargeable Silicon Battery - conceptual illustration. Credit: Technion – Israel Institute of Technology

The increased demand for sustainable energy sources prompted research groups to focus on battery research in order to store large-scale grid energy in a manageable and reliable manner. In addition, the rising demand of the electric vehicle industry, which mainly relies on current Li-ion battery technology, is expected to strain the current lithium production and divert it from more widespread use as portable consumer electronics. Currently, no technology has proven to be competitive enough to displace Li-ion Batteries.

Now, a team of researchers from the Technion – Israel Institute of Technology has developed a proof-of-concept for a novel rechargeable silicon (Si) battery, as well as its design and architecture that enables Si to be reversibly discharged and charged.

The research was led by Professor Yair Ein-Eli of the Faculty of Materials Science and Engineering. The team proved via systematic experimental works of the graduate student Alon Epstein and theoretical studies of Dr. Igor Baskin that silicon is dissolved during the battery discharge process, and elemental silicon is deposited upon charging. Several discharge-charge cycles were achieved, utilizing heavy doped n-type Si wafer anodes and specially designed hybrid-based ionic liquid electrolytes, tailored with halides (Bromine and Iodine), functioning as conversion cathodes.

This breakthrough could pave the way towards the enrichment of the battery technologies available in the energy storage market, with the technology potentially easing stress on the ever-growing market and serving the increasing demand for rechargeable batteries.

Silicon, as the second most abundant element on earth’s crust, was left relatively unexplored despite a high energy density of 8.4 kWh kg-1 on par with metallic Li 11.2 kWh kg-1. Silicon possesses stable surface passivation and low conductivity (dependent on the doping levels). Until now, no established rechargeable cell chemistry comprising elemental Si as an active anode has been reported outside LIB alloying anode.

In the past decade, several publications reported the incorporation of active silicon anodes in primary, non-rechargeable air-battery designs. Thus despite its high abundance and ease of production, the possibility of using Si as an active multivalent rechargeable anode was never explored until the team’s recent breakthrough.