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Published on February 19th, 2015 | by Tina Casey


EV Batteries Good, “Paper” EV Batteries 10x Better

February 19th, 2015 by  

No matter how fast the cost of oil drops, it just can’t keep up with the pace of improvements in electric vehicle batteries. In the latest development, a team of researchers at the University of California, Riverside, has come up with a paper-like material that could bring in a new generation of high-range batteries.

Now consider that legendary investor and noted wind energy fan Warren Buffett reportedly just ditched his interest in ExxonMobil to the tune of 41 million shares, and you can see why the prospects for future petroleum dependency are dimming with every advance in EV battery technology.

Paper EV battery 1

(a) SiO2 [silicon] nanofibers after drying, (b) SiO2 nanofibers under high magnification.

The New Paper EV Battery

The new EV battery announcement, from the school’s Bourns College of Engineering, involves a new paper-like material made from silicon in the form of spongy silicon nanofibers.

For those of you new to nanos, a nanometer is one billionth — not one millionth — of a meter, so when you get down to the nanoscale, you’re talking small.

To put it another way, each silicon nanofiber is more than 100 times thinner than your hair.

That’s why, although each fiber is spongelike, as a mass, they together form a somewhat crisper, paper-like material.

So Paper EV Batteries, So What?

The silicon “paper” could replace graphite in conventional lithium-ion EV batteries, and that’s where things start to get really exciting.

In a conventional battery, the anode (along with the cathode, the anode is responsible for charging and discharging) is coated with a material based on graphite. Researchers appear to have reached the performance limits of graphite, so the hunt has been on for better-performing materials.

Silicon is a good candidate because, according to the folks at Bourns, its electrical charger per unit weight of the battery is almost 10 times more than graphite.

However — and there’s always a however — silicon tends to degrade the battery when it expands.

The Bourns team resolved that problem by upcycling silicon into a mass of nanofibers, enabling the battery to cycle hundreds of times without degrading.

In the illustration below, you can see the upcycling process at work:

paper EV battery 2

(a) Schematic representation of the electrospinning process and subsequent reduction process. Digital photographs of (b) as-spun SiO2 nanofibers paper, (c) etched silicon nanofiber paper, and (d) carbon-coated silicon nanofiber paper as used in the lithium-ion half-cell configuration.

To ice the cake, based on the lab work so far, it appears the material could be manufactured at a commercial scale more easily than other graphite replacement materials, which would help shave down the cost of EV batteries.

You can get all the details from the research team’s article, “Towards Scalable Binderless Electrodes: Carbon Coated Silicon Nanofiber Paper via Mg Reduction of Electrospun SiO2 Nanofibers,” published in Nature Scientific Reports.

While you wade through that, the team will be working on scaling up the technology into a larger format for EV batteries.

Meanwhile, keep your eye on another up-and-coming EV battery material, nanocellulose.

What Now, Petroleum?

The advantages of EV technology are becoming more and more apparent practically by the minute, but we’re not saying that petroleum will disappear completely off the personal mobility map any time soon.

So, before you start cheering about the ExxonMobil divestment, keep in mind that Buffett’s Berkshire Hathaway firm reportedly upped its shares in SunCor at the same time.

We’re guessing that SunCor’s wind energy and biofuel operations attracted some of the interest, but the company is also a longtime oil sands developer in Canada, so… baby steps.

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Image Credits: Courtesy of UC Riverside. 

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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

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