Electrochemical Double-Layer Capacitors for Applications in Efficient Energy Storage and High Power Demand

摘要

Battery packs are required to absorb and deliver energy and power quickly, especially for heavy-duty missions. The burden and thermal stress have significant negative impacts on the battery operating lifetime. Ultracapacitors have been shown to absorb and deliver power rapidly. The capacitors can polarize an electrolyte solution and store energy via charge separation at the electrode-electrolyte interface, i.e. the formation of an electrochemical double-layer capacitance. This non-faradic process has no chemical reaction and the energy is stored electrostatically. The structure of ultracapacitor combines the features (i.e. long cycle life and high charge/discharge rate) of a conventional capacitor with an enhanced energy storage capability due to high electrode surface area and low internal resistance. This unique feature reveals a solution to overcome the limited lifecycle concerns of current onboard energy storage using advanced battery technologies. To better understand these unique features, a NiOOH/C ultracapacitor power module with 300 F capacitance at an operating window from 4.0 volts to 14.5 volts, using 10 asymmetrical electrochemical capacitors connected in series, was tested and evaluated through electrical characterization. The ultracapacitor module was applied to form a hybrid power system with an advanced Pb-acid battery, and was then tested & evaluated for high power demands. The hybrid power system potentially provides efficient energy storage needs for fuel saving in various mission fields.