When it comes to lithium-ion batteries, you can have fast charging speeds or high capacities -- take your pick. Now, Samsung researchers, working with Seoul National University, have figured out how to give batteries both qualities thanks to our old friend, graphene. By coating the electrodes with a thin, popcorn-shaped layer known as a "graphene ball," they were able to produce a battery that could fully charge in just 12 minutes with up to 45 percent more capacity. The research, if it pans out, could lead to lighter and faster-charging electric vehicles.

The problem with current lithium-ion tech is the dreaded "side reactions" that can wear away the electrodes, especially if the battery is charged too quickly. Researchers have found that nanomaterials like graphene can reduce the wear and tear on them, while simultaneously increasing their conductivity. The problem is that coating electrodes uniformly has proven to be a challenge, and many efforts have resulted in an undesirable tradeoff by increasing charging speeds but decreasing capacity.

Samsung's approach is to use a material assembly called a graphene ball to coat nickel-rich cathodes and lithium-based anode materials. The thin, popcorn-like substance can be coated onto the cathode evenly, making it more effective, while also giving the anode a capacity boost.

That technique increased both the stability of the battery and its conductivity, "improving the cyclability and fast charging capability of the cathode substantially," the researchers note. What's more, they hit energy densities of nearly 800 Wh/L, around the same as Li-ion batteries today used by Tesla (below) and others.

This isn't just a laboratory effort, as Samsung knows a thing or two about production. Its researchers figured out how to coat the electrodes using "Nobilta" milling in a way that's reasonably fast and accurate. The process, they say "would not require a substantial change" to current manufacturing techniques for advanced lithium-ion batteries like the ones used in EVs.

Batteries that can fully charge in 12 minutes would make EVs a hell of a lot more practical, even if capacities remain unchanged. It's hard not to believe that our hopes won't be dashed again, but maybe, just maybe, Samsung's manufacturing expertise could actually turn the research into something useful.

Source:
courtesy of ENGADGET

by Steve Dent

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