Supercapacitors vs. batteries.

The lead author has followed the subject for 20 years and is a globally acknowledged authority on the subject; he published the book ‘Dielectrics’ in 1973. 

The Executive Summary and Conclusions is insightful, detailed yet easily assimilated. An introduction focuses on lessons of the past and the objectives and challenges with the key components. Chapters follow respectively on separators and on electrolytes then one on active electrode materials and other important materials. Finally, there is an extensive chapter on developers.

In a balanced appraisal, ‘Supercapacitor Materials 2017-2027’ accepts that supercapacitors are only a few percent of the booming lithium-ion battery market but they have had less than one percent of the investment. Despite that, in many of the last 20 years they have improved their power density and energy density faster than lithium-ion batteries have done thanks to better hierarchical active electrodes and sometimes exohedral ones plus new electrolytes and so on.

Primarily, it has been due to new pairings of active electrode and electrolyte materials. Markets of billions of dollars remained elusive, however, due to high price caused by complex processing of basically low cost materials and limited energy density even after all that improvement but now help is at hand.

‘Supercapacitor Materials 2017-2027’, explains how, out of the spotlight, very important advances are occurring even beyond market leader Maxwell’s superlative opening up of new applications with tailored products. In the desert for supercapacitor manufacture – Europe – Skeleton Technologies has started to make supercapacitors partially based on graphene that set the record for power density and Yunasko in the Ukraine set the record for production hybrid supercapacitor energy density – up near lead acid and NiCd batteries and something Nippon Chemical says it will match next year.

Recognising the distaste of the Japanese motor industry for highly toxic electrolytes, Nippon Chemical in Japan jumped from nowhere to number two in supercapacitors in the world by making supercapacitors for cars that had benign electrolytes. ‘Supercapacitor Materials 2017-2027’ expresses the view that, partly because its supercapacitor suppliers have become more capable, China has recently reversed its policy on traditional hybrid vehicles, declaring that in 2030, 30% of cars made would be hybrids that do not plug in – candidates for supercapacitors. With GM now adopting them, supercapacitors are rapidly taking market share of stop-start systems for conventional vehicles.

‘Supercapacitor Materials 2017-2027’ finds that electrolytes with totally new chemistry are pairing well with new exohedral active electrodes. Hybrid capacitors are benefitting from totally new electrolyte-electrode pairings in the laboratory at least. Are the old rules of extremely hydrophobic assembly following complex high temperature processes really necessary for best performance?  Everything is being questioned now.

Learn how, in 2016-7, researchers at MIT and elsewhere developed a supercapacitor using no conductive carbon. Mircea Dinca, MIT associate professor of chemistry said: "We've found an entirely new class of materials for supercapacitors."

These metal-organic frameworks, MOF, are extremely porous, sponge-like structures with extraordinarily large surface area for their size, much greater than carbon materials, he claims, implying very high energy density on the way if these materials can be made more conductive. Virtually all double-layer supercapacitors today are made from carbon. They use carbon nanotubes, graphene, activated carbon, all shapes and forms, but nothing else besides carbon. So this is the first non-carbon, electrical double-layer supercapacitor.

Learn how the British have entered the fray, announcing new large molecule electrolytes based on large organic molecules composed of many repeated sub-units and bonded together to form a 3-dimensional network. Appraise the opportunity to match lithium-ion battery energy density without the short cycle life, poor power density and safety issues.

Are we going to have ‘batteries’ that can be fully discharged for safe transit and safe retrieval in a car crash unlike real Li-ion batteries? The Li-ion battery makers see no threat: the supercapacitor materials innovators intend otherwise. In three countries researchers are making supercapacitors that are load-bearing structures and others demonstrate stretchable supercapacitor fibres being woven, things batteries cannot do even when solid state because they swell and shrink on cycling.

Other old certainties are being questioned as well, each advance potentially opening up large new applications. A multibillion dollar market for the materials is in prospect but not overnight.