Some weeks ago, I wrote an article about Lithium Sulphur battery development. Now I have read another article (in the Economist magazine) about a new idea to improve battery power and charging times.
I am always fascinated with the way humans can build on a technology. I remember watching a TV programme about the evolution of the steam locomotive and how people worked on the efficiency of the engine by adding new pieces or redesigning the flow of the machine’s “process”. Battery development is a classic modern example of how humans can take an idea and figure out a better design – and I am fascinated at the experiments that take place and why they were performed (and in the order that ultimately provides the step forward).
One of the current “problems” with an electric car is the range and the perceived “range anxiety” that some drivers have, which stops them from buying a car. There is an assumption that most people drive long distances and that electric cars cannot match that need. I don’t believe that is true – most people I know drive less than 50 kms (30 miles) a day, ample for any electric car to deal with. The problem associated with long distances is that it takes a long time to charge up a battery, so this gives the industry some challenges.
One option is to have superchargers, high speed charging stations dotted on the highways – the Tesla approach. Another is to improve the battery so that it charges much faster.
It is this second approach that I am fascinated by. A researcher in South Korea has been experimenting with supercapacitors as a way of replacing the battery. A battery uses changes in chemical states of the electrolyte against plates of lithium, lead or another metal. A supercapacitor uses the electrolyte to work against static electricity on the surface plates of the capacitor.
The researcher has been using graphene as the material because each sheet is an atom thick! The result being a huge surface area to store static electricity. Apparently graphene has a surface area of 2,675 square metres per gram and comes from graphite. The problem to solve was how to make the graphene split into its natural sheets bearing in mind the thickness of each sheet. The answer was to blow up the graphite in a controlled way and this is where my curiosity was raised. The researcher used a two stage process and I wonder how he arrived at these steps:
1. He mixed powdered graphite with oxygen to make an oxide compound.
2. He then heated the mixture (high in oxygen atoms) at 160C in a device with a pressure one tenth of atmosphere (again I’d love to know the path that he followed to do this!) This caused steam and CO2 which increased the pressure splitting the graphite into graphene! He then removed some of the remaining oxygen and bingo, had a material that was ready to hold static electricity!
The prototype supercapacitor was able to hold as much energy/kilogram as a current lithium-ion battery but was fully charged in four minutes, a significant reduction in time. This is an important step forward in battery research.
The plan now is to figure out the life of the supercapacitor, upsize it to be suitable for wider usage and figure out how to make it cheaply. Combining this with a current supercharger could lead to the next evolution of the electric car industry and make the petrol powered range extender redundant. We are on the road to a new source of power.
great spotting – thanks for letting us know about this one – I look forward to the day when they truly crack it. Or don’t crack it as the case needs to be as robustness of the capacitor is a really important element and a 1 atom thick graphene capacitor surely won’t withstand the potholes so endemic in our minor road systems….