Scientists Tout Alternatives to Lithium Batteries

Matthew Boebinger, a graduate student at Georgia Tech, and Matthew McDowell, an assistant professor in the George W. Woodruff School of Mechanical Engineering and the School of Materials Science and Engineering, used an electron microscope to observe chemical reactions in a battery-simulated environment. (Rob Felt/Georgia Tech)

(CN) — The mineral resources needed to make batteries could become strained as global demand rises, but researchers at Georgia Tech say they may have found viable alternatives to traditional lithium battery construction.

The Georgia Institute of Technology scientists say new research shows that batteries made with potassium and sodium show promise — and could even be better than lithium — for battery power storage.

The team released a study Tuesday in the journal Joule that outlined its research on potassium and sodium batteries. It said that one of the reasons potassium and sodium have not been the ion of choice for battery construction is their tendency to decay faster than other ions like lithium.

“But we’ve found that’s not always the case,” Matthew McDowell, an assistant professor in the George W. Woodruff School of Mechanical Engineering, said in a statement.

The scientists studied how three ions – lithium, sodium and potassium – reacted with particles of the mineral pyrite. They found that pyrite was more stable during reaction with sodium and potassium, perhaps suggesting that a battery based on sodium or potassium ions could have a much longer life than previously thought.

As batteries charge and discharge, ions react with and penetrate the particles that make up the battery’s electrodes. This process causes large volume changes in the electrode’s particles, often breaking them up into small pieces, the study said. Because sodium and potassium ions are larger than lithium, it had been thought that these ions cause more degradation to battery electrodes.

Lithium-ion batteries have a high power density and relatively low cost that makes them optimal for energy storage in portable electronic devices, the electrical power grid, and the growing fleet of hybrid and electric vehicles.

According to the U.S. Geological Survey, batteries make up 39 percent of global lithium consumption.

The Georgia Tech scientists observed the chemical reactions through an electron microscope, using potassium, lithium and sodium and an iron sulfide battery electrode. According to the study, they found that iron sulfide was more stable during reaction with sodium and potassium than with lithium.

“We saw a very robust reaction with no fracture — something that suggests that this material and other materials like it could be used in these novel batteries with greater stability over time,” Matthew Boebinger, a graduate student at Georgia Tech, said.

Batteries have three main components — a cathode, an anode and electrolyte solution. When the cathode and anode are connected, electrons flow from the anode to the cathode, creating an electric current.

Lithium is typically found in the cathode of the battery, while the electrolyte is usually in the form of a lithium salt. The anode material is often carbon-based, usually graphite. A lithium- ion battery is able to produce more than twice as much power as an alkaline battery.

“Lithium batteries are still the most attractive right now because they have the most energy density. You can pack a lot of energy in that space,” McDowell said. “Sodium and potassium batteries at this point don’t have more density, but they are based on elements a thousand times more abundant in the earth’s crust than lithium. So they could be much cheaper in the future, which is important for large-scale energy storage — backup power for homes or the energy grid of the future.”

Worldwide lithium production increased by about 12 percent in 2016 in response to increased demand for battery applications, according to the USGS.

Lithium reserves exist on five continents — North America, South America, Africa, Asia and Australia. South America has the highest concentration, with about 66 percent of the world’s lithium reserves.

There are two main ways to produce lithium: brines and hard rock ore. With brines, the mineral has become concentrated in water solutions and is extractable. Hard rock supplies of lithium come in the form of pegmatites, which are found throughout the world, but lithium-rich granite pegmatites are much less common, making up less than 1 percent of pegmatite deposits.

Chile is the second largest producer of lithium in the world and number one in lithium reserves. Its reserves are held in brine deposits, with the main one being the Salar de Atacama. The area is about 3,000 square kilometers and has an estimated 6.8 million tons of lithium reserves.

Last fall, Stanford University scientists released research showing that additional lithium reserves may be present in volcanoes around North America, which could help decrease the United States’ dependence on international lithium supplies.

Although current annual consumption of lithium is small compared to the estimated global extractable lithium reserve, the Stanford researchers said lithium demand could become critical by 2030. The presence of lithium-ion batteries in mobile electronics and hybrid and electric vehicles necessitates discovery of new lithium resources to meet rising demand and to diversify the global lithium supply chain.

The Stanford study set out to demonstrate that supervolcanic lake deposits preserved within volcanic calderas have the potential for large lithium clay deposits.

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