Metal-free batteries raise hope for even more sustainable and also economical grids

Jan 13, 2023 12:15 PM ET
  • Rechargeable batteries that utilize ammonium cations as charge carriers could provide ecofriendly and sustainable substitutes to metal-ion-based batteries, researchers at KAUST show.
Metal-free batteries raise hope for even more sustainable and also economical grids
Image: KAUST

Metal-ion batteries, such as lithium-ion batteries, are the go-to power storage remedy. They dominate the marketplace for portable customer electronics and also electric vehicles because of their high power density as well as versatility. Nevertheless, metal ions used in the electrolytes originate from minimal as well as decreasing sources, which intimidates long-lasting availability. Their toxicity and also flammability can be unsafe as well as harmful to the environment.

There have been numerous attempts to generate ammonium-ion-based batteries to solve sustainability as well as environmental issues due to the fact that these cations are lightweight and also easy to synthesize as well as recycle. Nonetheless, ammonium cations are prone to reduction into hydrogen and also ammonia at low operation potential, preventing the batteries from accomplishing their full capacity. They also dissolve readily in electrolytes, making them challenging to integrate into electrode products.

Husam Alshareef, postdoc Zhiming Zhao as well as coworkers established a high-efficiency metal-free battery by combining an ammonium-cation-containing electrolyte with carbon-based electrodes. The graphite cathode as well as the organic semiconductor anode are cheap, environmentally friendly and eco-friendly, Zhao says.

With the ammonium cations, the researchers chose hexafluorophosphate ions as adverse charge carriers and also made use of the capacity of graphite to reversibly accommodate these anions within its layers to develop a "dual-ion" battery. In the battery, cations and anions all at once insert right into their corresponding electrode throughout charge cycles as well as are launched into the electrolyte throughout discharge cycles.

This differentiates their work from other studies, Zhao says.

"We created an electrolyte that is both antioxidative and also antireductive by screening a series of solvents resistant to high voltage and likewise taking into account its reduction stability," Zhao says.

The antioxidative solvent primarily solvated anions taking part in the cathode response, while its antireductive equivalent developed a solvation ball around cations involved in the anode reaction. "This arrangement is important for battery stability," Zhao clarifies.

The battery outperformed existing ammonium-ion-based analogs with a record procedure voltage of 2.75 volts. "It is currently possible to create high-energy nonmetallic ion batteries that can take on metal-ion batteries," Zhao says.

The team is currently functioning to enhance the performance to get closer to large-scale applications. "We are discovering anode products with a higher capacity, which is important for boosting the power density," Zhao says.

Alshareef's group is developing cheap choices to lithium-ion batteries, particularly for grid-scale storage space. "To ultimately completely decarbonize the grid, the battery costs should considerably come down," says Alshareef. Replacing lithium with nonmetallic charge carriers, such as ammonium ions, can aid lower these prices.

The study is released in the journal Angewandte Chemie International Edition.

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