Researchers at Kansas State University (KSU), USA, have developed a technique using silicon oxycarbide, enabling the use of a silicon and graphene combination as an electrode material.

Silicon electrodes have been known to become brittle after so many charge/discharge cycles, and graphene has thus far been unable to provide enough volumetric capacitance for a sustainable utility. Associate professor of mechanical and nuclear engineering Gurpreet Singh and his team overcame these issues by developing a self-standing anode material that consists of ‘silicon oxycarbide glass particles embedded into a chemically modified graphene oxide matrix’.

Singh said: “Silicon combined with graphene is better than a bulk silicon electrode. However, nano-silicon/graphene electrodes fail to satisfy key requirements for any practical applications. [T]he constituent silicon, carbon and oxygen atoms are arranged in a random 3D structure, and any excess carbon precipitates out into string-like or cellular regions. Such an open 3D structure renders large sites for reversible lithium storage and smooth channels for solvated lithium-ion transportation from the electrolyte.”

The KSU team of researchers claims that the electrode capacity can reach 600 miliampere-hours per gram, or 400 miliampere-hours per cubic centimetre after 1,020 cycles. They expect that the power density, which is the maximum power output per unit mass, is expected to be three times greater than current Li-ion batteries.

The new concept for battery electrodes can be up to 10% lighter than others, has a near perfect cycling efficiency, and can operate in temperatures as low as -15^oC, offering potential space and aerial applications.

The research of Singh and his team can be viewed in the online journal Nature Communications.

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