An engineer from Kansas State University has developed a paper-like battery electrode made out of silicon oxycarbide-glass and graphene.
Gurpreet Singh, associate professor of mechanical and nuclear engineering, and his research team developed the battery electrode to be 10% lighter than ordinary battery electrodes. It also has almost 100% cycling efficiency for more than 1,000 charge-discharge cycles and is made of low-cost materials that are byproducts of the silicone industry.
The electrode functions at temperatures as low as -15° C, which means it could potentially be used in a plethora of unmanned aerial vehicle and aerospace applications.
Singh's team has been exploring new material combinations for batteries and electrode design for some time, but it has been difficult to incorporate graphene and silicon into practical batteries because of challenges such as low capacity per volume, poor cycling efficiency and chemical-mechanical instability.
To overcome these challenges, the team developed the self-supporting electrode comprised of a glassy ceramic called silicon oxycarbide, which is sandwiched between large platelets of chemically modified graphene, or CMG. The electrode has a high capacity of approximately 600 miliampere-hours per gram that is derived from silicon oxycarbide.
"The paper-like design is markedly different from the electrodes used in present-day batteries because it eliminates the metal foil support and polymeric glue—both of which do not contribute toward capacity of the battery," said Singh.
The design, made of 20% chemically modified graphene platelets, saved approximately 10% in total weight of the cell, creating a lightweight electrode that can store lithium-ion and electrons at practical performance levels.
Even when the electrode cells are kept at very low temperatures, they can deliver a capacity of 200 miliampere-hour per gram, which is different from most batteries, which fail to perform at such low temperatures.
"This suggests that rechargeable batteries from silicon-glass and graphene electrodes may also be suitable for unmanned aerial vehicles flying at high altitudes, or maybe even space applications," said Singh.
How it’s made
The silicon oxycarbide material is prepared by heating a liquid resin until it breaks down and transforms into sharp glass-like particles. The silicon, carbon and oxygen atoms get rearranged into a 3-D structure and any excess carbon seeps into cellular regions. This creates large sites for reversible lithium storage and smooth channels for lithium-ion transportation.
Singh’s goal is to produce the electrode material at larger dimensions, and he would like to work with industry partners to explore production of lithium-ion battery fuel cells. He even alludes to the possibility of 3-D-printing silicon oxycarbide one day.