You’ve heard of thin film wearable solar cells, and now a thin film, flexible battery is in the works. A team of researchers at Rice University has come up with a new lightweight battery that combines the flexibility of graphene with the high storage capacity of inorganic metal compounds. You don’t usually find that high flexibility – high storage combo in battery technology, but Rice managed to cook one up by taking the supercapacitor approach.
A New Flexible Battery: Look Mom, No Lithium!
The problem that Rice set out to solve is this one: the inorganic metal compounds which provide the most efficient storage capacity are typically brittle, but the carbon based storage systems that provide flexibility can’t approach the theoretical storage capacity of inorganic systems.
The Rice flexible battery solution is a supercapacitor that acts like a battery. Supercapacitor is batteryspeak for an energy storage device that discharges speedily, so in other words the Rice team figured out how to get a supercapacitor to discharge at a more useful rate.
The heart of the new Rice battery/supercapacitor is a layer of nickel fluoride 900 nanometers thick, etched with pores only 5 nanometers across (about 5 billionths of a meter), sandwiched in between layers of an electrolyte (potassium hydroxide in polyvinyl alcohol, for those of you keeping score at home).
The nanostructured pores provide more storage area for higher capacity. Although this approach would appear to be exceptionally delicate, the Rice team found that it stood up to 10,000 charge/recharge cycles without any significant degradation of the electrode-electrolyte interface, and it still had 76 percent of its capacity.
The new battery also took 1,000 bending cycles during the test.
We Built This Flexible Battery!
Another problem that the Rice battery solves is the lithium supply problem. Right now, lithium-ion is the gold standard for energy storage with renewable energy applications spanning electric vehicle batteries as well as wind and solar arrays, but the global lithium market is subject to price spikes and supply issues, so diversifying the energy storage supply chain is a significant Obama Administration goal.
So, we took a look at the funders behind the research and who do we find but our old friends over at the Air Force Office of Scientific Research (along with the Peter M. and Ruth L. Nicholas Postodoctoral Fellowship).
AFOSR has been right on top of cutting edge clean tech, so the new thin film energy storage concept goes right along with other recent AFOSR projects, including solar cells enhanced with quantum dots and a cutting edge energy management system combined with solar power.
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