The most critical and costly components of a supercapacitor are the active electrodes, electrolyte and then separator. Indeed, solid state supercapacitors in the laboratory have no separator. The structure and chemistry of electrodes/electrolytes are critical.
New forms must be optimised as an electrode-electrolyte
pair. Opportunities for developers of the necessary fine chemicals and new fabrication technologies are considerable. Most commercial electrodes are bulk carbon with macropores leading to micropores ie “hierarchical”. Best laboratory results for improved energy density for battery replacement and time constant for electrolytic
capacitor replacement are “exohedral”. This means nano structures - carbon allotropes such as graphene
, carbon nanotubes
and nano-onions (spheres within spheres). In addition there are aerogels with particles of a few nanometers. Graphene
often wins in the laboratory but it is uncertain when or even whether it will win commercially.
Structure and materials
The structure of a supercapacitor and supercabattery is introduced together with the materials and parameters needed for the applications with the greatest business potential. Particularly focussed on the primary market need for the future - lower cost with higher energy density - the candidate families of material are assessed and progress reported and predicted. Notably, that means electrode and then electrolyte
materials, with separators third in importance. For electrodes, that includes many types of graphene
, carbon nanotubes
, nano-onions, aerogels and chemically-derived carbons. Important for future electrolyte
needs are new neutral aqueous electrolytes
permitting low cost current collectors now with higher voltage, new ionic liquids that work at low temperatures and new organic solvents - less toxic and non-flammable.
For electrodes, the various hierarchical (wide to narrow pores in bulk), exohedral (large area allotropes) and thin film options are compared. They are related to various end points from micro-supercapacitors to structural ones forming part of a building, smart skin on ships or e-fibers in textiles. Emerging, there is a wealth of different needs for high added value functional materials
Best performers and key players
The material needs of large supercapacitors appearing in electric vehicles, grid, railway and other electrical engineering applications are considered. In electric vehicles, for example, they will partly or wholly replace traction batteries. In addition they will replace inverter capacitors and be even more useful in many other EV locations including regenerative braking backup and bus door opening.
We forecast the best energy density that will be achieved in volume production in the next ten years and in 15 years from now, the best candidate materials, capacitor structures and electrolytes
for achieving this and the value market resulting. We show which electrode functional materials
best leverage the next-generation electrolytes
Many key players in the industry are identified and their business/research plans revealed based on a host of ongoing interviews.