Graphene Extends Batteries Life And Efficiency

Since Lithium-ion batteries have witnessed a growing application in portable electronics and electric vehicles, researchers are keen to improve their performance and cost further. In those efforts, researchers have made a promising discovery to enhance the life and performance of these batteries.

With its cheap and energy-efficient performance, Lithium-ion batteries have revolutionized the use of electricity. Any battery works by creating chemical energy between the cathode and the anode, and converting it into electricity.

As the chemicals in the two ends of the battery are utilized over time, it may not completely recover to its original state. The more times we charge the batteries, the less batteries we have left.

The foremost challenge in battery use is the dissolution of transition metals from the cathode material. Such dissolution results in unwanted side reactions, which eventually stick to the anode, thereby reducing anode performance.

Therefore, cobalt-bearing cathodes are preferred instead of manganese cathodes. However, cobalt is a relatively expensive and scarce metal. In between the search for better alternatives, Graphene enters into play.

In a collaboration, Caltech and Jet Propulsion Laboratory have proposed a novel method to coat lithium-ion battery cathodes with graphene. This not only improved battery performance, but also reduces its reliance on scarce metals like Cobalt.

Since graphene is an allotrope of carbon, it offers better capacity, cycling stability, and capacity retention. Additionally, it’s readily available and more effective than metals like Silicon.

The widespread use of graphene wasn’t possible until Caltech senior research scientist David Boyd discovered that graphene could be produced at room temperature. Before this discovery, graphene production required temperatures up to 1,000 degrees.

Following this breakthrough, the collaborated work successfully demonstrated the improved performance and suppression of transition-metal dissolution.

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“Demonstrating a reliable trend in battery-cell performance requires consistent materials, consistent cell assembly, and careful testing under a range of conditions,” says the lead authors.

“It is fortunate that the team was able to do this work so reproducibly, although it took some time to be sure.“

While researchers already knew the use of graphene in reducing transition metal dissolution, its thin coating was challenging. Graphene’s direct deposition of batteries proved devastating for cathodes.

Therefore, Boyd and colleagues came up with a dry coating approach. Using a phenomenon called ‘ordered mixing,’ the guest particle was successfully coated on the host.

“This is a good idea we might be able to use with graphene! We can first manufacture graphene guest particles—graphene encapsulated nanoparticles (GEN)—using our room-temperature method, and then dry coat a very small amount of it (1 percent in weight) onto the host cathode material so that graphene effectively covers and protects the cathode,” said Boyd.

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Journal Reference

1. David A. Boyd, Cullen M. Quine, Jasmina Pasalic, Channing Ahn, William C. West and Brent Fultz. Suppression of Transition Metal Dissolution in Mn-Rich Layered Oxide Cathodes with Graphene Nanocomposite Dry Coatings. 2024. Journal of the Electrochemical Society 171 100532 DOI 10.1149/1945-7111/ad867f