Findings at Supercapacitors USA 2013



The third edition of IDTechEx's Supercapacitors event was held in Santa Clara, California on 20-21 November. The event was co-located with other IDTechEx events such as Printed Electronics, Graphene Live and Energy Harvesting & Storage, which along with Supercapacitors USA 2013 achieved the presence of 2,200 delegates.

Maxwell Technologies, market leader in the industry, opened the conference with a presentation by Dr Priya Bendale. An interesting point of the presentation were the results she presented from Rochester Institute of Technology and Argonne National Laboratory about how much lithium ion battery lifetime can be extended with the use of supercapacitors. Based on a model with Plug in Hybrid Electric Vehicle, which was tested at lab level to confirm the impact of using supercapacitors on battery performance - the study revealed that cycle battery capacity degradation was decreased by a factor of 2 and the impedance degradation reduced by a factor of 6. Why is this relevant? As you know lithium batteries account for half the cost of an electric vehicle, and price is still one of the barriers for their mass uptake. If you manage to extend the lifetime of a battery you reduce the total cost of ownership of the car. Therefore by extending the lifetime of lithium ion batteries, supercapacitors can effectively reduce the total cost of ownership of electric vehicles and contribute to their mass scale adoption.

Mr Anthony Kongats, from Cap-XX the Australian supercapacitor leader, spoke about the use of supercapacitors with energy harvesting. He presented an interesting case study about the use of supercapacitors and energy harvesting to support devices with e-Ink Displays such as Electrophoretic Paper Displays, which are low average power devices. Many autonomous powered devices could benefit from a lower power display. Some examples of this are: Time, temperature, status, etc in WSNs/M2M devices; e-Book readers; Electronic Shelf Labels; RFID tags; Electronic forms; Signature pads; PDAs & POS terminals; and Medical devices. The key lesson was that many electronics applications have low average power, but need bursst of high power. The environment has abundant energy, but delivered at low power and often in bursts, so energy harvesting source needs an efficient energy storage system. Batteries have limitations in harvesting that can effectively be addressed by supercapacitors: maintenance, temperature and high energy/high power/long lifetime balance.

Mr Lars Stegmann from VISEDO, a Finnish hybrid electric powertrain developer leader, did a presentation about how they have successfully integrated the use of WIMA's supercapacitors in high power hybrid industrial machines (300 HP) and based on power train optimisations assisted by the use of supercapacitors. This was based on their product Visedo® CMS (Capacitor Management System) and WIMA® Supercapacitors. The additional benefits are in cost, weight, life time, size, safety, and of course fuel efficiency. They have achieved payback periods of just 1 year, based on fuel efficiency, plus reducing carbon emissions and noise levels.

Mr Oliver Gross from Chrysler, presented SAE's work (the largest producer of consensus based mobility standards in the world) for the development of supercapacitor standards for the automotive industry. This is the capacitive energy storage standard - J3051, in which companies like Caterpillar, Chrysler, EnerDel, FastCap Systems, Ioxus, Johnson Controls, JSR Micro, Maxwell Technologies, Saft, Tardec, United Chemi-con and Toyota are participating. Mr Gross stressed the importance of more supercapacitor companies to take part in the process.

Other relevant presentations were the ones from UC Davis, on which there was a call for standardised methods to measure power density in the industry and Robert Bosch about their activities in energy storage and JSR Micro. As in Supercapacitors Europe 2013, this show presented a strong track on graphene use in supercapacitors.

Graphenea opened discussions on Graphene in Energy Storage applications through making an overview of the industry, in which relevant points were raised. There are different graphene synthesis technologies in the market that produce different levels of homogeneity, area and have different susceptibilities for industrial scalability. There is a market oversupply situation and graphene oxide prices are declining sharply due to production efficiency and economies of scale. Graphene is at the beginning of the hype cycle of technology expectations.

Graphene Frontiers presented microsupercapacitor with hybrid material structure composed of both graphene and carbon nanotubes. The micron scale size of these devices was meant to integrate into modern electronics for AC line filtering and discrete power sources with reduced size and weight, and with a planar geometry to accommodate the trend for thinner products and incorporate into existing production techniques. Graphene Frontiers had licensed this hybrid technology from Rice University with plans of commercialization. However after significant market analysis they decided against this business model and did not renew their license. One of the main reasons of this decision was that manufacturing of the graphene/CNT hybrid requires CVD growth processes that are not yet at commercial scale. To be competitive with traditional technologies such as the Aluminum Electrolytic Capacitor which costs less than a dollar, manufacturing costs need to be driven down significantly. Due to these challenges Graphene Frontiers is now aggressively entering the sensors market with a graphene hybrid device; the extreme conductivity, high sensitivity and consistency of graphene makes it the ideal sensor material.
Angstron Materials, was perhaps the company that presented the most promising results on graphene implementation in energy storage devices. Their latest research has been focused in using graphene as an additive in multiple composites for supercapacitor electrodes, interestingly the company is using ionic liquids as electrolyte, achieving at lab level energy densities of about 80 Wh/kg and power densities of 1kW/kg. This means the same energy density as a lithium ion battery but with higher power. At product level the company presented respectable results of a 350 F cell with 14 Wh/kg, which is higher than most commercially available supercapacitors. The company is still working on an optimal configuration to offer higher energy density than current supercapacitors while maintaining the prized power density stability and lifespan.
In relation to manufacturing techniques, the Stevens Institute of Technology, presented an interesting method consisting of Inkjet-printed graphene for microsupercapacitors. Graphene oxide water ink droplets are applied through print head nozzles. An infrared heat lamp reduces the graphene oxide to graphene. This technique allows the manufacturing of graphene layers by controlling the spacing and diameter between graphene oxide droplets. The results showcased present higher capacitance and energy density than powder graphene electrode manufacturing techniques reported in the literature.