Cobalt-free battery leans on nickel for extra energy storage
As a relatively rare and expensive heavy metal, cobalt serves as a vital but costly part of today’s lithium batteries, not just in terms of dollars but also for the environment and well-being of those tasked with mining it. A new battery design from the University of Texas at Austin may help address these issues, with the team demonstrating a new type of battery architecture that performs on par with conventional devices, while being entirely free of cobalt.
Due to its excellent conductivity and durability throughout charging cycles, cobalt has served as a key material in the cathode of lithium batteries since their inception, but it has come under fire lately due to the harmful effects of the related mining operations. These include exposing workers to dangerous levels of toxic metals, but also the degradation of natural landscapes and water supplies.
So there is considerable interest in sourcing alternatives, with some promising possibilities to emerge of late, including an experimental battery developed at IBM that uses materials sourced from saltwater instead.
The University of Texas at Austin team is throwing another candidate into the mix, having developed a new class of cathodes that don’t involve cobalt at all. Generally speaking, the cathode of a lithium battery is made from a mix of metal ions including cobalt, nickel and aluminum. Cobalt is the most expensive of these elements and can account for around half the materials cost of the entire battery.
“Cobalt is the least abundant and most expensive component in battery cathodes,” says study author Arumugam Manthiram. “And we are completely eliminating it.”
The team achieved this by tweaking the recipe to produce a cathode made of 89 percent nickel, with the rest formed from manganese and aluminum. The key, the researchers say, is that during the synthesis the ions of these different metals are distributed evenly across the cathode. This overcomes a key shortcoming with other designs, where the ions bunch up in places and degrade the performance of the battery.
In addition to overcoming this fatal flaw, the team says the new battery has some other advantages. The higher nickel content enables the battery to store more energy, which would mean greater range for electric vehicles or longer battery life for mobile devices per charge. The team has created a new startup to try and bring the new technology to market.
“We are increasing the energy density and lowering the cost without sacrificing cycle life,” Manthiram said. “This means longer driving distances for electric vehicles and better battery life for laptops and cellphones.”
The research was published in the journal Advanced Materials.
Source: University of Texas at Austin