Nissan and Ecotricity put 13 more rapid chargers on UK motorways
DOE issues RFI for next-gen photovoltaic technology

Monash University team develops graphene-based supercapacitor with energy density of 60 Wh/L

A research team at Monash University (Australia) led by Professor Dan Li of the Department of Materials Engineering has developed a new strategy to engineer graphene-based supercapacitors (SC), resulting in an energy density of 60 Wh/liter—comparable to lead-acid batteries and around 12 times higher than commercially available SCs.

The approach could make SCs more viable for widespread use in renewable energy storage, portable electronics and electric vehicles. A paper on the work is published in Science.

SCs are generally made of highly porous carbon impregnated with a liquid electrolyte to transport the electrical charge. Known for their almost indefinite lifespan and the ability to re-charge in seconds, the drawback of existing SCs is their low energy density. With a low energy density of 5-8 Wh/liter, SCs are unfeasibly large or must be re-charged frequently.

It has long been a challenge to make SCs smaller, lighter and compact to meet the increasingly demanding needs of many commercial uses.

—Professor Li

Graphene, which is formed when graphite is broken down into layers one atom thick, is very strong, chemically stable and an excellent conductor of electricity.

To make the compact electrode, Professor Li’s team exploited an adaptive graphene gel film they had developed previously. They used liquid electrolytes—generally the conductor in traditional SCs—to control the spacing between graphene sheets on the sub-nanometer scale. In this way the liquid electrolyte played a dual role: maintaining the minute space between the graphene sheets and conducting electricity. Unlike in traditional hard porous carbon, where space is wasted with unnecessarily large pores, density is maximized without compromising porosity.

Porous yet densely packed carbon electrodes with high ion-accessible surface area and low ion transport resistance are crucial to the realization of high-density electrochemical capacitive energy storage but have proved to be very challenging to produce. Taking advantage of chemically converted graphene’s intrinsic micro-corrugated two-dimensional configuration and self-assembly behavior, we show that such materials can be readily formed by capillary compression of adaptive graphene gel films in the presence of a nonvolatile liquid electrolyte. This simple soft approach enables sub-nanometer scale integration of graphene sheets with electrolytes to form highly compact carbon electrodes with a continuous ion transport network. Electrochemical capacitors based on the resulting films can obtain volumetric energy densities approaching 60 watt-hours per liter.

—Yang et al.

To create their material, the research team used a method similar to that used in traditional paper making, meaning the process could be easily and cost-effectively scaled up for industrial use.

We have created a macroscopic graphene material that is a step beyond what has been achieved previously. It is almost at the stage of moving from the lab to commercial development.

—Professor Li

The work was supported by the Australian Research Council.


  • Xiaowei Yang, Chi Cheng, Yufei Wang, Ling Qiu, and Dan Li (2013) Liquid-Mediated Dense Integration of Graphene Materials for Compact Capacitive Energy Storage. Science 341 (6145), 534-537 doi: 10.1126/science.1239089



A liter could contain the energy of a 1200 kg car doing 45 mph, and so would be a good candidate for a regenerative braking system.


In 2010 the highest available EDLC specific energy was 30 W⋅h/kg (approximately 0.01 MJ/kg).


Not just regenerative braking, but an all-around energy buffer for acceleration, active suspension, you-name-it.

If the supercap can be tapped for several hundred horsepower at any time, the car's engine can be cut to just the power required for cruise.  Say, climbing a 5% grade at 65 MPH at gross weight (in the neighborhood of 50 HP).  When Fiat is getting twice that out of a 990cc 2-banger, that's just not going to be a challenge.  Everything else cycles in and out of the supercap, with the engine operated for best thermal efficiency.  That would make just about every car get Prius-level economy.


You name it - exactly

Given that the electronics people have devices to extract and utilise the decreasing voltage outputs (not just smoothing.)

Was it GCCongress report? descibed energy (voltage)boosting in Direct Acting Wave Generators whereby the voltage tension is increased when capacitive plates are pulled apart by mechanical forces (wave action.)

I am led to believe that self discharge is a substantial issue for SC's.
Exactly how serious and comparison to various battery chemistry discharge which could then be compared with
Liquid H2 and LNG storage losses.
We are practically knowledgeable re fossil fuels.

Also missing is the important Wh/Kg estimate. Presumably better than or at least similar to 12 times the 30 mentioned by SJC.


Supercap leakage times are on the order of an hour or more to drop to 90% of charge.  Figuring 20%/hour energy loss, that is losses of about 200 watts in a 1 kWh unit.  It would need cooling, but not much.

Kinetic energy of a 2000 kg vehicle moving at 120 kph is about 300 Wh.


You shouldn't expect to use supercaps for long/medium term storage, transfer the energy to a battery for that.

Use the supercaps for bursts of energy (such as braking and taking off 60 seconds later).


This has possibilities for V2G in combination with total system energy management.  The supercaps can be used as very short-term energy buffers for the grid.  The grid may be able to supply energy to top them off just before driving, and a "heat battery" in the engine cooling system could be used as a dump load by the V2G system and to pre-heat the engine to reduce cold-start efficiency losses and pollution.

The comments to this entry are closed.