Rechargeable silicon redox battery for renewable energy storage

Israeli researchers have developed a device that combines a reversible Si anode with halide cathodes and uses hybrid electrolytes to enable cell recharging. In the proposed system configuration, silicon is dissolved during the battery discharge process, and upon charging, elemental silicon is deposited.

August 4, 2022 Emiliano Bellini

A conceptual illustration of a rechargeable silicon battery

Image: Technion – Israel Institute of Technology

From pv magazine Global

Researchers from the Technion – Israel Institute of Technology have designed a rechargeable silicon (Si) battery for stationary storage applications that can be reversibly discharged at 1.1 V and charged at 1.5 V.

The device combines a reversible Si anode with halide cathodes and uses hybrid electrolytes to enable cell recharging. In the proposed system configuration, silicon is dissolved during the battery discharge process, and upon charging, elemental Si is deposited. The hybrid electrolytes, which were tailored with halides such as bromine and iodine, reversibly support the Si electro-dissolution and electrodeposition processes in the same cell formation.

“During the discharge process, Si electrodissolution occurs at the anode and, dissolved halides are reduced at the cathode,” the scientists said. “The charging process entails Si species electrodeposition and halide oxidation.”

They assembled all cell components in an Ar-filled glovebox and prepared the silicon electrodes from n-type 4′′ silicon wafers. They also left the cells to rest for three hours to detect possible leakage and used platinum foils as counter electrodes.

After several cycles, the battery achieved a coulombic efficiency of approximately 80%, while showing gradual cell degradation. The cell showed limited power capabilities of 0.1 mA cm^–2,” the scientists said. “The presence of appreciable fluoride species is crucial in both establishing surface activation and battery operation, and their depletion is directly linked to cell performance degradation.”

The academics presented the novel battery concept in “Rechargeable Silicon Redox Batteries,” which was recently published in Advanced Energy Materials.

“The feasibility of the new design paves the way for higher specific energy devices aiming towards the segments of low power applications. These findings undoubtedly warrant further investigation and electrolyte optimisation,” they said.

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