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Sun04202014

Technology

Making it stick, adding boron improves graphene’s ability to absorb lithium

Making it stick, adding boron improves graphene’s ability to absorb lithium
A theory developed at Rice University determined that a graphene/boron compound would excel as an ultrathin anode for lithium-ion batteries. The compound would store far more energy than graphite electrodes used in current batteries. (Credit: Vasilii Artyukhov/Rice University)

Rice University scientists have developed a battery anode made up of a mix of graphene and boron for use in high-capacity lithium ion batteries.

Graphene is considered a promising material with many applications. Despite being only one-atom material, it has a massive surface area. Counting both sides, one gram would cover around 2,630 square meters or nearly half a football field.

Battery manufacturers hope to take advantage of this massive surface area to store lithium ions. However, ions do not stick to graphene very well. That is where the boron comes in.

Graphene is carbon-based and replacing some of the carbon atoms making up graphene with boron gives it a better ability to store lithium.

According to theoretical physicist Boris Yakobson, the graphene/boron anode should be able to hold a lot of lithium and perform at a proper voltage for use in lithium-ion batteries.

“Having boron in the lattice gives very nice binding, so the capacity is good enough, two times larger than graphite,” he said. Graphite is the most commonly used electrode in commercial lithium-ion batteries.

A fully lithium infused sheet of graphene/boron would have a theoretical capacity of 714 milliamp hours per gram. This translates into an energy density of 2,120 watt-hours per kilogram. The material also displayed the ability to retain it structure – not radically expand or contract – during the charge cycle which could lead to longer material and battery life.

The researchers will be working on a way to synthesize the material in larger quantities. As of now, the techniques used by Rice are not commercially available.

The Honda Research Institute and the Department of Energy supported the research. Computations were performed on the Rice DAVinCI system and the National Institute for Computational Sciences Kraken, both funded by the National Science Foundation, and the National Energy Research Scientific Computing Center Hopper, supported by the D.O.E. – EcoSeed Staff



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