Charged Up on Supercapacitors

The use of electrochemistry to study and optimise alternative energy storage is the focus of the Andreas research group.  Their research concentrates on supercapacitors, an energy storage system that is similar to batteries, but uses a different storage mechanism.  By using supercapacitors, up to a million times more charge can be stored than in a conventional capacitor. Supercapacitors also drastically improve the cycle life of the energy storage system (up to a million cycles with a supercapacitor, compared to batteries which only provide thousands of cycles).

Recently there has been significant interest in the use of supercapacitors in vehicle applications (cold starting assistance and hybrid fuel cell-capacitor cars), and power line backup. Such supercapacitor systems can be composed of environmentally friendly materials, and are also ideal for storing the energy produced by alternative energy systems such as solar- or wind-power. However, one very poorly understood aspect of supercapacitor behaviour which limits their practical application is self-discharge: the loss of voltage exhibited by a supercapacitor as it sits in a charged state for long periods of time.  If a supercapacitor is charged but not used immediately it will spontaneously lose charge over time until, eventually, the supercapacitor is dead.

The Andreas lab is researching the causes of supercapacitor self-discharge and will examine the factors which change the rate of self-discharge.  Electrochemical methods are used to investigate possible mechanisms of discharge and to determine what is happening at the interfaces and in the materials of the supercapacitor.   A more complete understanding of self-discharge processes will help the researchers in the Andreas lab minimise or even prevent self-discharge altogether, extending the life and applicability of supercapacitors worldwide.

This research is supported by a Natural Science and Engineering Research Council (NSERC) Discovery Grant.  Additionally, Dr. Andreas was recently awarded an NSERC Strategic Grant which will provide funds to support the recruitment of additional high-quality researchers in her laboratory.  Dr. Andreas has also received a Canadian Foundation for Innovation (CFI) Leader Opportunity Fund Award.  This award will provide the financial means for the installation of a state-of-the-art electrochemical laboratory that will incorporate vital electrochemical instrumentation.

Among these instruments will be an electrochemical quartz crystal microbalance, which allows the researcher to measure microgram (a millionth of a gram) or nanogram (a billionth of a gram) mass changes while the system is under potential control.  This means the mass of a supercapacitor electrode can be measured while it is being charged, discharged or when it is undergoing self-discharge.  In this way, the gain or loss of oxygen or carbon (or some other species) can be tracked.

Additionally, the award will provide a Multipotentiostat, a very powerful instrument that allows eight experiments to run simultaneously.  Since each self-discharge experiment may take several hours to several weeks to run, the ability to run many of these experiments simultaneously will significantly enhance this research.