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New plastic material could solve energy storage challenge, researchers report
In the race to lighter, safer and more efficient electronics — from electric vehicles to transcontinental energy grids — one component literally holds the power: the polymer capacitor. Seen in such applications as medical defibrillators, #polymercapacitors are responsible for quick bursts of #energy and stabilizing power rather than holding large amounts of energy, as opposed to the slower, steadier energy of a battery. However, current state-of-the-art polymer capacitors cannot survive beyond 212 degrees Fahrenheit (F), which the air around a typical car engine can hit during summer months and an overworked data center can surpass on any given day.
“Advances in the full systems for electric vehicles, data centers, space exploration and more can all hindered by the polymer capacitor,” said co-first author Li Li, postdoctoral scholar in Penn State’s Department of Electrical Engineering. “Conventional polymer capacitors need to be kept cool to operate. Our approach solves that issue while enabling four times the power — or the same amount of power in a device four times smaller,
Capacitors store less energy than batteries, but they charge and discharge their power much quicker. A mobile phone, for example, has a battery that charges from a power source. The energy it stores comes from many internal chemical-electrical reactions over a period of time that keep the phone working. Extra functions, like the flash on the phone’s camera, require a burst of energy. A capacitor is responsible for discharging that extra bang of power.
Most polymer capacitors fail at high temperatures because they are made of polymers with long chains of molecules that have low glass-transition temperatures, meaning the molecules turn from rubbery and malleable to brittle and fragile like glass at relatively low temperatures. Polymers can be found in natural materials, but are also synthetically produced to make thin, flexible films, thick, rigid plastics and everything in between. When the polymers and other material mix, their nanostructures — at the atomic level — form interfaces to varying degrees. They can leak electric charges, the researchers said, and the problem worsens at high temperatures.
“Normally, you can’t have both high energy density and high temperature tolerance in one dielectric polymer — we achieved both by mixing two commercially available high-temperature polymers.
The researchers combined #PEI, originally produced by General Electric and often used in pharmaceutical production, and #PBPDA, a polymer with high heat resistance and electric insulation. When mixed together at suitable temperatures, the molecular components of the polymers self-assembled into #3Dstructures, which the researchers used to make #thinfilms.
source : Penn State College of Engineering
