An ultracapacitor, also known as a supercapacitor or an electric double layer capacitor, is a long-lasting energy storage device that can store and release electrical energy faster than a battery.
While batteries store energy through chemical reactions, standard capacitors store energy in an electric field between two electrodes — similar to the static charge that accumulates when a balloon is rubbed against someone’s hair. However, capacitors have a very low storage capacity because they store energy in the form of electrons, which repel each other.
Ultracapacitors, on the other hand, do not store electrons directly. Instead, they store positively and negatively charged ions and use a liquid electrolyte to facilitate the flow of energy; unlike in batteries, no chemical reactions are involved. This results in much faster charge and discharge times and makes ultracapacitors ideal for automotive applications that require quick bursts of power or quick storage, such as when energy is recaptured through regenerative braking.
Ultracapacitors also have a much longer life cycle than batteries because there are no physical or chemical changes speeding up degradation. A typical battery can handle 2,000 to 3,000 charge cycles, whereas an ultracapacitor can withstand more than 1 million cycles. Ultracapacitors are more stable than batteries, do not contain heavy metals, and have an operating temperature range between -40° C and 65° C.
Replacing the 12V battery
Ultracapacitors lack the storage capacity to serve as the propulsion battery in electric vehicles (EVs), but they are an attractive alternative to the 12V lead-acid battery that powers low-voltage systems such as instrumentation panels, entertainment systems, LED lighting and sensors.
While EVs typically use DC-to-DC converters to step down the power from the primary vehicle battery to supply low-voltage components, traditional 12V lead-acid batteries are still commonly used to provide a redundant power supply. Some EV models use 12V or 14V lithium-ion batteries instead of lead-acid batteries, since the higher energy density of lithium-ion technology allows them to achieve a smaller size while providing the same power. However, they are more expensive and cannot provide the same surge current that lead-acid batteries provide.
Enter ultracapacitors. Weighing about 60 percent less than their lead-acid battery counterparts, 12V ultracapacitors offer a solution to help OEMs optimize mass and provide the required surge current – while lowering costs, thanks to their long life spans. They also help address vehicle reliability; battery trouble is often listed as a top cause of roadside breakdowns.
In 2022, Aptiv was awarded a new commercial program with a major OEM for our ultracapacitor module, Aptiv’s Rapid Power Reserve. Part of our ASIL-D-rated 12V power delivery network, the ultracapacitor provides instantaneous backup power to safety-critical systems such as steering and braking.
Aptiv’s solution combines battery management control software with power electronics to deliver maximum performance at an optimized cost and power density. As the only supplier of both the brain and the nervous system of the vehicle, Aptiv is uniquely positioned to provide solutions that optimize the entire vehicle architecture.