‘Hibernating’ batteries for seasonal storage can release energy when heated

‘Hibernating’ batteries for seasonal storage can release energy when heated

‘Hibernating’ batteries for seasonal storage can release energy when heated

Scientists continue to explore advanced battery technologies to help us unlock the full potential of renewable energy in an effort to solve the intermittent problem of electricity from the sun and wind.

A team at Pacific Northwest National Laboratory (PNNL) has come up with a new design that meets some important requirements in the field, and researchers have demonstrated a “hibernating” battery that can preserve its energy for months at a time.

The type of energy storage technology at the research center is called a molten salt battery. These batteries have been around in various forms for over 50 years and are considered grid-scale renewable energy storage solutions due to their low cost and use of common materials.

These devices use molten salt as the electrolyte, which is a solution that carries an electric charge between the battery’s two electrodes (cathode and anode).

Keeping the electrolyte at high temperature keeps the salt molten and sees it flow like a liquid, but at room temperature it turns solid.

The PNNL team has used these properties to produce what it calls a temperature-based hibernation battery.

The device consists of an aluminum anode and nickel cathode, which are soaked in a molten salt electrolyte doped with sulfur for additional capacity.

The battery is charged by heating to 180°C (356°F), as ions flow through the liquid electrolyte to generate chemical energy.

Cooling the battery to room temperature solidifies the electrolyte and freezes the ions in place, locking in the energy until the battery is reheated, allowing the energy to flow again.

For this reason, the scientists, who also call the device a “freeze-thaw battery,” are optimistic about its potential to scale up, despite the prototype being the size of an ice puck.

Its theoretical density is 260Wh per kilogram, which is higher than today’s lead-acid and flow batteries, and the material cost of its energy storage is about $23 per kilowatt-hour. kWh is about $6. In testing, the battery maintained 92 percent of its capacity for 12 weeks.

“It’s a lot like growing food in your garden in the spring, putting the excess in a container in the refrigerator , and then thawing it out for dinner in the winter,” said lead author Minyuan “Miller” Li.

We have recently seen some promising innovations in molten salt battery technology.

Typically, molten salt batteries use a ceramic separator between the anode and cathode to control which molecules can pass through.

In 2018, an MIT team showed how to use a more durable steel mesh instead.

Last year, a team at Sandia also demonstrated a cheaper version that could operate at temperatures far lower than traditional designs.

The PNNL team also opted for an alternative to the ceramic separator used in typical molten salt batteries, replacing it with fiberglass, which they say is cheaper and more durable.

Ultimately, scientists hope the technology could provide a seasonal energy store, where energy is harvested at one time of year and used at another.

And, because the battery can sit idle while maintaining most of its stored energy, it will only need to be charged and discharged a few times a year.

“You can start envisioning something like a large battery on a 40-foot tractor trailer parked in a wind farm,” said co-author Vince Sprenkle. “The battery is charged in the spring and the truck is driven to a substation on the road where it can be used if needed in the summer heat.”

The scientists have patented the technology and published their research in the journal Cell Reports Physical Science.