Graphene Batteries Could Soon Be Inside Solar Drones
Graphene has become well known as a very promising carbon derivative, with applications ranging from water filters to solar panels. Recently, research into graphene’s electrical properties has lead scientists towards developing “super capacitors”, or high capacity quick charging batteries. Graphene’s surface area is made up of a single layer of graphite, making it ideal as a medium for storing electricity.
A basic look into capacitors
Similar to electrochemical batteries, capacitors act as an energy storage medium for electricity. While electrochemical batteries can store large amounts of electricity, they take a long time to charge and often lose energy via heat. Electric vehicles are a perfect example of the usefulness/inconvenience ratio between electrochemical batteries, their charge rate and their energy capacity. Tesla’s model S can take you 250 miles on a single charge, but could take over 40 hours to recharge from a standard 120 volt outlet. Capacitors can charge much faster but currently cannot hold as much energy as an electrochemical battery can (at least, not currently…).
(Fig.1) A conventional capacitor is made up of two layers of conductive materials that eventually become positively and negatively charged. Between these layers is an insulator that prevents loss of energy internally. The amount of charge a capacitor can hold depends on the surface area of the two conductors, the distance between them, and the dielectric constant of the insulator.
Supercapacitors (the concept graphine batteries are based on), on the other hand, differ from conventional capacitors because they do not contain a solid insulator. Instead, the two conductive plates in the cell are coated with a porous material, generally “activated carbon”. The two conductors are then immersed in an electrolyte solution. These capacitors can hold more electrons, and therefor more power. In the image to the right (Fig.2), the separator represents the porous material separating the graphene-coated conductors (labeled “carbon”).
Powering Solar Drones
One of the biggest challenges with any unmanned mobile vehicle is storage of energy. A drone can have all the latest technology providing it with state-of-the-art data input and worldwide communication mobility, but still be limited to a mere 50 kilometer flying distance due to limited energy storage. The addition of solar panels can sometimes increase range and flight time by tenfold, but is still limited by energy storage technology currently available. Some of the best batteries out there today (Lithium based) can charge reasonably quickly and provide sufficient energy to power the drone during the night, but tend to lose energy in the form of heat and internal resistance as mentioned above. A supercapacitor could solve both of these energy losses, as they lose substantially less heat energy and have a negligible internal resistance when compared to a lithium based battery.
Graphene batteries are still a long way from being available, but there are several research projects being conducted on graphene and its electrical applications and potential (Fig.3). The current struggles lie in reliable manufacturing methods, but substantial progress is being made. Newly discovered applications for graphene are constantly being realized, inspiring more interest and in turn more funding. The potential for graphene in a world of technology and electricity is huge, and the drone community is itching for progress!
Take a look at this video on graphene’s potential: