Researchers at Oak Ridge National Laboratory (ORNL) and Lawrence Berkeley National Laboratory (Berkeley Lab) focused on a key battery component, the anode, where electricity comes out. Most current commercial lithium batteries have anodes made of graphite, a form of carbon. However, scientists at ORNL incorporated a special form of the compound titanium dioxide into the anode instead, and they found significant improvements. At the same level of current, it takes the new ORNL battery just six minutes to be 50 percent charged, while a graphite-based lithium-ion battery would see a mere 10 percent increase in the same timeframe. The new ORNL battery also outperforms faster-charging lithium titanate batteries (which use tiny particles of lithium titanate in the anode in place of graphite to speed charging) and, unlike such batteries, has a sloping discharge voltage that is good for controlling the state of charge.
ORNL’s new battery has the potential to be used in a wide range of heavy-duty applications, especially places where increased strength and safety are at a premium such as hybrid electric vehicles, power grids and the energy storage systems of wind and solar power generators. Additional research needs to be performed, but scientists at ORNL believe that if titanium dioxide proves scalable in batteries, they could be on the market within five years.
Berkeley Lab researchers are taking a different approach. They designed a new anode made from a tailored polymer – a material made of millions of repeating units – that conducts electricity. It also embeds silicon particles, which in turn bind to a lot of lithium ions (much more than graphite anodes can). These improvements give the battery a much greater capacity – the ability to store much more energy – than current designs. Even better, they maintain that increased capacity after hundreds of charge-discharge cycles.
The better anode built by Berkeley Lab could contribute to lowering the cost and extending the range of electric cars. Researchers say the anode can be built at a comparatively low cost, and in a way that’s already compatible with established manufacturing technologies. And they offer that the tailored polymer that makes the battery better could see use in a wide range of other products too.