New cathode design promises battery sustainability

Energy storage has a vital role to play in the transition to clean, renewable energy sources. And while other battery types, and other forms of storage entirely, are out there, lithium-ion will likely represent the largest share of storage projects connecting to the world’s electricity grids, as well as powering electric vehicles and other important technologies.

This has led many to highlight concerns around materials commonly used in today’s lithium-ion batteries, and the search for alternatives is a focus for scientists and research and development teams the world over.

One group of scientists led by Lawrence Berkeley National Laboratory in the United States worked with a type of material called a disordered rocksalt with excess lithium (DRX). They developed a cathode design that relies on a different type of reaction to lithium-ion batteries produced today, and could potentially hold more lithium ions, and open a range of potential materials to reduce reliance on cobalt, nickel and other more expensive materials.

“DRX materials have enormous compositional flexibility – and this is very powerful because not only can you use all kinds of abundant metals in a DRX cathode,” explained Berkeley Lab scientist Gerbrand Ceder. “But you can also use any type of metal to fix any problem that might come up during the early stages of designing new batteries. That’s why we’re so excited.”

The group’s work with DRX materials is described in the paper Non-topotactic reactions enable high rate capability in Li-rich cathode materials, published in Nature Energy. “We demonstrated significantly improved rate performance in cation-disordered rocksalt cathodes due to a non-topotactic reaction, which stands in contrast to the conventional view that fast Li transport is favored by perfectly topotactic systems,” the group explains. “We believe that well-engineered non-topotacticity provides a new opportunity to design high capacity cathode materials.”

A topotactic reaction is one that alters the crystalline structure of a material, and is the type of reaction that allows today's lithium-ion batteries to charge and discharge.

Accelerated development

And though they acknowledge that new battery materials can take 20 years or more to commercialize, the group hopes to accelerate this timeframe with DRX materials, noting that other groups in Europe and Asia have also begun research projects on similar materials. “Advances in battery technologies and energy storage will require continued breakthroughs in the fundamental science of materials,” said Jeff Neaton, Berkeley Lab’s Associate Lab Director for Energy Sciences. “Berkeley Lab’s expertise, unique facilities, and capabilities in advanced imaging, computation, and synthesis allow us to study materials at the scale of atoms and electrons. We are well poised to accelerate the development of promising materials like DRX for clean energy.”