Secreted away in an industrial park in Lane Cove, Sydney, a team of materials scientists and engineers coat an aluminium substrate with a special sauce of activated carbon.
Down the corridor, technicians disassemble a Kindle ebook reader, and replace its internal battery with a flat prismatic supercapacitor in a flat silver packet, allowing it to run off the power generated by a solar panel.
And soon, the same supercapacitors made by CAP-XX (pronounced with one “X”), scaled up and connected in parallel, may be found in micro-hybrid and hybrid electrical vehicles from major international automotive makers.
We talked to Pierre Mars, Vice President for Quality and Applications Engineering at CAP-XX, to find out how Australian innovation could soon make drivers’ lives a whole lot easier.
CAP-XX’s core IP was first developed by the CSIRO in the mid-to-late 90s. Anthony Kongats, who was then involved in electrolytic manufacturing at Plessey Ducon in Meadowbank, started working with CSIRO to integrate their activated carbon technology into supercapacitors.
“CSIRO was being asked to get external funding for some of their research work, as their budget was being tightened,” explained Mars.
“So Anthony funded some of that work, and got the rights to the IP for the carbon coating in return for that funding, and that was the start of what was then energy storage systems.”
Early supercapacitors from CAP-XX retained the cylindrical form factor of regular capacitors, but were much larger, and could deliver a few thousand farads of capacitance.
“The party trick was that you could charge it up, go into a meeting, whack a paper clip across and you’d melt it,” Mars said.
After raising some seed funding for the startup, CAP-XX surveyed the market to find the prime focus for its technology, and decided to start making small and slim supercapacitors in a prismatic form factor for consumer electronics such as wireless modems and LED camera flashes.
“Back in 2000…as a startup company we recognised that the automotive industry would be too slow moving for us to succeed,” Mars explained.
“It has only been in the last couple of years as global warming, reduce emissions, improved fuel economy, price of gas, all that sort of stuff, has now driven people into looking at what we would call micro-hybrid, and to hybrid solutions.”
This prompted a decision in late 2011 to enter the automotive market.
“Market acceptance has just come now. People now have a genuine need because they are being pushed on fuel economy and emissions reduction.”
Cranking it up
Micro-hybrid vehicles use the start-stop system, which automatically shuts down and restarts the engine during stops. By reducing idling time, the system helps cut fuel consumption and emissions.
However, the start-stop system places a lot of strain on the battery, and current implementations require the use of expensive heavy duty batteries such as absorbed glass material (AGM) variants in order to cater for the required load.
“Instead of starting your car three or four times a day, you are now starting it forty, fifty, hundred times a day,” Mars pointed out. “Particularly in city traffic.”
The solution is to pair up a supercapacitor system with a smaller battery, and use the supercapacitor to provide the repeated high power cranking current required to start the engine.
Since the battery no longer experiences the cranking current, it can be smaller and lighter, which, together with the light weight of supercapacitors, would provide further fuel efficiencies.
Additionally, since supercapacitors can accept extremely high currents, such a system could also be connected to regenerative braking in order to recover even more power.
“Stop-start systems started with higher end cars and are coming along in the last two or three years. So we started looking at it, and we also started getting interest in it,” Mars said.
“People were making enquiries, and we could see the opportunities, so we made some prototype large cells. We now have a low volume production line here to make those, to meet sample needs for evaluation.”
While the current coating allows an impressive power density of around 90kW per kg, to cater for the automotive systems, CAP-XX looked to alter its proprietary coated foil technology to be higher energy.
In May 2013, CAP-XX announced its GC1 EDLC supercapacitor cells which provide 1400 Farads and Equivalent Series Resistance (ESR) of around 0.26 milliohms. The low ESR means it is possible to draw amperes out of the supercapacitor, and only experience a low voltage drop.
How to make supercapacitors
To make supercapacitors, create the coated electrode foil, and cut it out. The positive foil layers are joined together to construct the positive and negative terminals, then ultrasonically weld them together.
The assembly is then put into a silver pouch package, filled with electrolyte, sealed, and tested.
Since the key intellectual property for CAP-XX is in the coating of the electrodes, it manufactures its coated foils in Australia, and sends them to Malaysia for volume assembly into supercapacitors.
It's Malaysian manufacturers utilise production equipment from CAP-XX, which was shipped over along with work instructions. A data acquisition management system allows the Australian company to have oversight over the manufacturing process and test results.
In the case of the automotive supercapacitors, as they are currently being provided in sample quantities, they require small runs, which can be done in Australia.
Showing off one of the sample units, Mars said the form factor, similar to that of a large prismatic lithium-ion battery, allows for easier system designs, and is easier to pack into a smaller space compared to cylindrical cans.
“This has been made by off-the-shelf production equipment that was designed to make lithium-ion batteries,” Mars said.
“That is why we can set up a low-volume line here cost-effectively, because we can buy some of the key equipment at reasonable prices from China. That’s what makes the automotive market attractive. The capital cost to set it up is reasonable considering the potential returns.”
When asked about the potential for competitors to reverse engineer their products, Mars said the ultrasonic welding made it impossible to do so with the coated foil.
“Assembly-wise, anyone can cut it up and see how it’s put together, but making the production equipment to do it effectively is non-trivial,” he said.
“It’s quite a high barrier to entry. You have to have the right coated foil that will work with the electrolyte, the right separator…it’s a system. If you don’t get all the bits right, then you will have short life, or other problems.”
A powerful future
Much of CAP-XX’s business is in export – while there are a few small-scale design houses in Australia who buy supercapacitors, most of the volume comes from overseas.
“Often we would work with the design team, help the distributor win the design by giving application support to the customer, and then the customer will get the unit made in China or Singapore or Malaysia themselves, and we drop-ship our parts to the manufacturing location,” Mars explained.
CAP-XX is still supplying supercapacitors for electronic systems, and is working on a surface-mountable supercapacitor.
At the moment, all supercapacitors have to be mounted on a circuit board as a secondary operation in production, after the reflow process.
Standard supercapacitors cannot pass through a reflow oven, because they have liquid electrolyte absorbed into the pores of the activated carbon. The vapour pressure inside can cause the package to rupture when the unit is subjected to the temperatures (260°C) inside a reflow oven.
To make a surface mountable supercapacitor, CAP-XX will need to develop fundamentally different materials that do not exert vapour pressure.
By making a surface-mountable supercapacitor, CAP-XX hopes to make the creation of products bearing supercapacitors more cost-effective and better suited for high-volume applications.
On the automotive front, CAP-XX has already had a number of top tier suppliers sampling its supercapacitors, and is hopeful of a mass-market breakthrough within the next two to four years.
The company is also speaking to racing companies, for possible inclusion of supercapacitors in Kinetic Energy Recovery Systems (KERS), a variant of regenerative braking used by racing cars.
“When the racers go around the corner, they capture that energy, then push that energy out when they accelerate out of the corner. They get an extra one or two hundred horse power on top of what their engine gives them, in a short burst,” said Mars
The light-weight nature of supercapacitors is a point of special interest for racers looking to minimise their vehicle weight.
In the manufacturing process itself, CAP-XX continues to work on streamlining production, reducing costs by 25 to 50 percent, and improve materials utilisation and yield.
With the company also looking to explore applications in energy harvesting and wireless sensors, CAP-XX is also hoping to improve its supercapacitors’ life, allowing them to last longer in set-and-forget type applications.
CAP-XX has licensed its technology to Murata, a Japanese manufacturer, and will be looking for more licensing agreements with large players who can effectively scale up the production and distribution of the supercapacitors.
And while it is possible that CAP-XX will eventually become a pure IP company, Mars is keen to keep manufacturing its own parts, and be directly in the market, since it allows the company to engage directly with its user-customers, explore new applications, and get feedback.