We expect all of our electronic gadgets from personal music players and laptops to tablets and smartphones to offer cutting-edge quality, including the longest run-time, brightest screens and highest-definition audio and visuals. While most consumers realize that energy storage plays a part in providing optimal device performance, many overlook the power component of devices’ energy consumption. Most electronic applications require both energy and power to meet all of the functional requirements of the application.

Power can be described as the rate at which energy is transferred. Energy storage devices can store a lot or a little energy, and can be capable of either charging and discharging quickly or slowly, indicative of the power capability of the device. The holy grail of energy storage, therefore, is a device that would deliver high levels of energy at a high transfer rate, which, despite many recent reports to the contrary, does not yet seem feasible.

Two common types of energy storage devices receiving attention today—from researchers, investors and engineers—as possible answers to the consumer gadget energy challenges are supercapacitors and batteries. Supercapacitors, also known as ultracapacitors, are known for their high power capability and possess relatively low energy density. Compared to other energy storage technologies, supercapacitors store less energy but deliver what energy they do store at a very high rate. Further the ultracapacitors also accept charge at a high rate as well, which is a very important characteristic. Conversely, batteries store much more energy, but have lower power capability than supercapacitors. So in the energy storage and electronic device world, we presently don’t need just one technology or the other—we need the best of both, which supercapacitor and battery manufacturers are hard at work trying to do. However, today, this is not reality.

While the recent news about a particular high school student’s invention of advanced supercapacitor technology that would eliminate slow cellphone charging appeared promising at first, upon deeper examination of the development, it can be shown that while the invented device can charge rapidly, it will not have enough energy to provide meaningful run-times for the phone. The student’s proposed technology would be incorporated into a cellphone to charge the phone to maximum capacity in mere seconds instead of hours.

This capability is in fact a characteristic commercially available in supercapacitors today, but to imply that this new invention can power a cellphone in a meaningful way is misleading: The device lacks the energy necessary to run the cell phone for any reasonable period of time. While the public has lauded the development of this supercharging technology, what was not described in the reports about this device is the low energy density, which is not nearly high enough to expand energy availability from the supercapacitor into the realm of a battery. While this and other reports like it may indicate that this technology could soon replace batteries, it simply cannot, due to the low energy availability — which will only provide a fraction of the run-time consumers require. The supercapacitor can provide great power, but it will not be enough for days, or even hours, of actual use.

Further, from a practical perspective, if a device has high energy density along with a high energy content, then to charge such a device in seconds would require a charging circuit that can supply and handle high levels of current. In the case of a cellphone battery, it would require currents in excess of 100 amps continually while charging for those seconds. This is not a consumer-friendly manner of charging devices at home for everyday use.

I look forward to the day when a mass-produced device can provide quick cellphone charging with the run-time we expect. But when that technology comes, it will not be a supercapacitor or a battery, but an entirely new technology that has not yet been named — possessing all the best of both. There are many scientists and engineers devoting their careers to the discovery and commercialization of such a technology and it is making for exciting times in the energy storage industry now and in the future.

Mike Everett is Vice President of Advanced Power/Energy Development and Chief Technical Officer at Maxwell Technologies.