Bipolar technology firm EEStor Corp. and FWG have revealed independent test results demonstrating the energy density of its doped-carbon supercapacitors is on average 53.31Wh/kg.
A report by inspection, verification, testing and certification company SGS-CSTC was prepared after tests on five single cell devices weighing around 36 grams each at its electrical safety laboratory in Shenzhen, China.
Results on the component layers of a ‘phase one device’ included the packaging and connections in the calculation but excluded case material and intercell partitions on the basis the completed device was in a bipolar arrangement and only one cell per device was tested.
The report concluded that further testing and certifications were needed. It added: “These results were looked for as a first important milestone and were dictated by economic considerations. More expansive characterisation is needed.”
Ian Clifford, founder and chief executive officer of the Canadian company believes the technology needs to deliver around 50Wh/kg to replace the Group 27 lead-acid battery.
Clifford told BEST the assumptions from the results were open to interpretation with regard to not being complete devices.
He said: “To contextualise, this set of single-cell tests validate the internal results of multi-cell bipolar devices that have been built and tested by FWG, but not yet third-party certified.”
When asked about energy density of a business-as-usual battery and timeframes on commerciality, Clifford was more cautious.
He said: “The target of the Phase-1 technology is to disrupt lead-acid storage at commercially viable levels: cost, performance, longevity, sustainability, environmental impact.
“The manufacturing process, which is built around standard paper-manufacturing modalities and utilising doped-carbon as the “ink”, is elegantly straightforward cut and collate type assembly without clean-room requirements. Much effort has gone in to the design and planning of scalable commercial production. Given this, time to market should occur within timeframes that are exceedingly quick in the world of traditional battery manufacturing.”
A battery expert told BEST: “In their words ‘the individual cells would form part of a bipolar battery’. And this is one of the bugbears of bipolar technology. Anyone can make an individual cell and get good Wh/kg if you leave out a large part of the construction. If ever a full size practical bipolar battery is made then it would be of interest.”
Third party certification of full-scale devices is planned with Intertek and the National Physical Laboratory of Great Britain, with SGS continuing as an independent third party certification partner.
Last month, BEST reported how EEStor had entered into a letter of intent (LoI) to acquire and merge with UK research firm FWG.
The LoI paves the way for the integration of EEStor’s composition modified barium titanate (CMBT) powder and the UK firm’s graphene and carbon-based materials.
FWG’s battery uses doped carbon structures in a bipolar arrangement in order to produce a compact device with energy density in the region of lead-acid, around 50-60Wh/kg depending on size and physical structure.