Background: Super-capacitors provide other significant advantages over large batteries. They are capable of delivering higher peak currents to facilitate large dynamic electric load swings are essentially maintenance free and operate across a wider range of temperature and charging life cycle. They are also more environmentally friendly. However unlike batteries super-capacitors provide a less stable voltage output over time as the stored charge depletes.

Solar photovoltaic (PV) power generation systems require electrical inverters to convert direct current (DC) into alternating current (AC) the standard type of electricity supplied by utilities. Inverters make up a large portion of capital costs because they must be replaced periodically over the lifetime of a solar system. The mean time before failures (MTBF) is about 3 -5 years for most PV inverters while the expected lifetime of PV cells is 20 years or more. Reductions in inverter costs as well as extended lifetimes would significantly reduce overall system costs.

Three phase PWM converters are widely used in numerous applications including adjustable speed motor drives uninterruptible power supplies and grid integration of renewable and distributed resources such as solar photovoltaics. Some of the important metrics of performance for these converters are related to the amount of total harmonic distortion (THD) in the line current switching losses in the power devices and dynamic performance.

UC San Diego researchers have developed the methods materials and designs for producing electrochemical capacitors based on carbon nanotube electrodes with enhanced capacitance due to the addition of charged defects. Specifically exposure to argon is used to controllably incorporate extrinsic defects into CNTs and increase the magnitude of both the pseudo-capacitance and double-layer capacitance by as much as 50% and 200% respectively compared to untreated electrodes.

Background: Testing and characterization of electrochemical energy cells such as microbatteries is critical in the development of battery-powered microelectronics. Discharge and cycle testing of microbatteries may require days or weeks of continuous monitoring and often must be conducted in a closed environment such as a glovebox. Galvanostatic studies are at present the preferred method for characterizing the performance of energy cells but characterization of microbattery performance requires galvanostats with microamp or better resolution.

Background: Currently MnO2 is commonly coated onto current collectors to form very thin films with a thickness of ten to one-thousand nanometers in order to minimize the limitation of poor conductivity. Therefore the relative amount of MnO2 on current collector is always low and does not provide sufficient energy and power density.

Background: Although a battery can store significant amounts of energy it cannot deliver it quickly. But a battery can be used to charge a capacitor which then can provide much power all at once. Supercapacitors consist of electrodes collectors a separator that keeps the electrodes out of electrical contact and an electrolyte which allows ions to move freely through the separator. Typically supercapacitors use aqueous electrolytes which can be unstable at high voltages or organic liquid electrolytes like acetonitrile which are highly toxic and flammable.

Supercapacitors are divided into three families, based on electrode design: