The 30-year battery: New chemistry holds promise

For bulk storage on the grid, Stanford research develop a new chemistry that could lead to durable, fast-charging batteries for storing wind and solar energy.

Wind power, but still no storage. GE

While consumers may simply crave longer-lasting batteries for electronic gadgets, the holy grail for many material scientists is batteries that can pump power into the grid for hours.

Stanford University researchers today detailed a new electrode material they claim holds promise for grid storage batteries that can work 30 years without a dramatic decline in performance.

In the lab, the copper and iron-based nano-engineered material was able to take 40,000 charge/discharge cycles while still maintaining an 80 percent capacity. By contrast, the lithium ion batteries used in consumer electronics degrade noticeably after only a few hundred cycles.

The batteries used for grid storage today are usually a sodium sulfur or lithium ion chemistry. But Stanford researchers found that sending smaller hydrated potassium ions, the electrically charged atoms that carry charge between the two ends of a battery, works well with its electrode material.

"Potassium will just zoom in and zoom out, so you can have an extremely high-power battery," Yi Cui, an associate professor of materials science and engineering, and one of the co-authors of a paper published today in Nature Communications, said in a statement.

It's all about the atomic structure. Stanford researchers have developed an electrode material made from copper and iron that it says can perform 40,000 charge/discharge cycles with a relatively low dip in capacity.
It's all about the atomic structure. Stanford researchers have developed an electrode material that it says can perform 40,000 charge/discharge cycles with a relatively low dip in capacity. Nature Communications

The anode material, which is called copper hexacyanoferrate, promises to be durable over time and be able to dispatch large amounts of power, which is needed for grid applications, according to Cui.

The researchers chose to make a water-based electrolyte, which should be less expensive than the materials used in lithium ion batteries. Other components require iron, copper, carbon and nitrogen, which are cheaper than lithium, said Colin Wessels, another co-author of the paper and graduate student in materials science and engineering.

Finding electrode materials that don't degrade over time and can handle megawatts of power flow is one of the biggest challenges in battery engineering now. For grid storage applications, price is one of the biggest challenges since batteries are often competing with fossil fuel power generators.

The Stanford research is a step toward finding the components needed for bulk energy storage, but the team is not prepared to make a commercial product. Using a copper hexacyanoferrate would require development of an opposite electrode that would create sufficient voltage to produce a flow of electricity.

Batteries are not the only way to store energy on the grid. Pumped hydro facilities, where water is pumped at off peak times and stored in a reservoir, remain the lowest cost approach. Underground caverns for storing compressed air is another bulk storage option, although both options have limits in terms of where they can be done.

 

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