Scientists at UCLA have developed hybrid supercapacitors that can store as much charge as a lead acid battery, yet can be recharged in seconds compared with hours for conventional batteries.
Current supercapacitors can charge in seconds and can be used for a million recharge cycles but, unlike batteries, they do not store enough power to run computers and smartphones. Now, the UCLA researchers have combined two nanomaterials to create a new energy storage medium that combines the best qualities of batteries and supercapacitors.
The new device combines manganese dioxide, which is used in alkaline batteries because it holds a lot of charge and is cheap and plentiful, and laser-scribed graphene. Laser-scribed graphene is a material that can hold an electrical charge, is very conductive and charges and recharges very quickly. The researchers have specifically designed the graphene structure for porosity and surface area – allowing the device to pack much more energy per unit volume and mass.
Like other supercapacitors, the device charges and discharges very quickly and lasts for more than 10,000 recharge cycles. But it stores six times more energy than a conventional supercapacitor and holds more than twice as much charge as a typical thin-film lithium battery. Yet it is only one fifth the thickness of a sheet of paper.
Supercapacitors are usually stacked on top of each other and packaged into a single unit to provide a sufficiently high voltage. But this device is so thin that the researchers have been able to integrate it inside a solar cell array. The supercapacitor can quickly store electrical charge generated by the solar cell during the day, hold the charge until evening and then power an LED overnight.
The research team is now exploring how to build hybrid supercapacitors on a large scale. They believe that fabricating the hybrid supercapacitcors will be readily scalable because it does not require extreme temperatures or expensive “dry rooms” needed to produce most supercapacitors.