This atom-thin coating can supercharge battery performance

 

Researchers from the University of Queensland have developed a super-thin cathode coating that can help high-voltage lithium-ion batteries last longer.

Rechargeable lithium-ion batteries power much of modern life, including our smartphones, computers, and electric vehicles, as well as renewable energy storage.

However, they are not without flaws. Li-ion batteries can have safety hazards depending on their chemistry, and they may contain cobalt, a pricey and poisonous metal that has been utilized in batteries for decades.

A group of nanotech experts led by the University of Queensland (UQ) has published research describing a new super-thin protective covering that could solve some major li-ion battery problems.

The study, which was published in Nature Communications, shows how this layer can“more than double” the life expectancy of high-voltage li-ion batteries, from a typical average of several hundred charge/discharge cycles to over 1000.

The researchers chose to focus on enhancing the cathode, the positive side of the battery, according to senior author Professor Lianzhou Wang of UQ's Australian Institute for Bioengineering and Nanotechnology and School of Chemical Engineering.

“If you look at a battery, there are two key components: a cathode and an anode, and in between there’s a membrane and also there are some electrolytes,” Wang told create.

“The cathode is about 40% of all the costs in the battery system — and it’s also the bottleneck".

“If you look at the current state-of-the-art cathode material in commercial products, the specific capacity that cathode can deliver is about 150 to 200 milliampere hour per gram (mA h g), but the very common anode materials — like graphite, for example — can deliver more than 300 to 370 mA h g,” he said. “So, one side’s capacity is much higher than the other side.”  

The UQ team set out to create a new cathode layer that might withstand corrosion while also extending battery life.

Atomic-thin crystal coating 

Despite the lithium-ion battery's importance (the researchers who invented it got the Nobel Prize in Chemistry in 2019), finding a cathode material that has a high energy density, is cost-effective, and does not harm the environment has been difficult.

Early-generation lithium-ion batteries, which were initially commercialized by Sony in the early 1990s, use lithium cobalt oxide as a cathode material, which is highly efficient but has other drawbacks, according to Wang.

“The lithium cobalt material is good, but the cobalt itself is toxic, and the cost is quite expensive, so this is a problem — and also it’s got some safety problems,” he continued.

Alternatives such as nickel and manganese can be stable, but they can dissolve into the electrolyte and damage the battery system over time.

Wang and his team used the epitaxy technique to build a coating for a lithium, nickel, and manganese-based cathode material. The cathode particles are coated with a one-atom thick layer of lanthanum, nickel, manganese, and oxygen crystal.

This protective layer allows for a high-voltage battery (about 4.5V) while also reducing cathode erosion.

“This is the key innovation of work, with this mono-layer protection, the dissolution of the nickel and manganese become more difficult,” Wang explained.

When tested using a graphitic carbon anode and a non-aqueous electrolyte solution at a testing facility, the team discovered a capacity retention of about 77 percent after 1000 cycles.

Scaling up and commercialising  

The protective material could be commercialized in two to three years, according to Wang, although there is still work to be done. The next step is to scale up, moving from coin-sized batteries to medium- and large-scale testing, in collaboration with industry and the CSIRO.

Trailblazer, a newly formed $242.7 million federal government program, aims to speed up the commercialization of research like this.

Curtin University, in collaboration with UQ and James Cook University, will lead the Resources and Critical Minerals stream of the program, which was announced in April.

Curtin's Director of Commercialisation, Rohan McDougall, told create that 33 industry partners are on board.

“They range from companies that are looking at how to process and value-add to minerals, [such as] Linus, who are looking at collaborating on optimisation of processing rare earths in Australia and their processing facilities internationally,” he said. 

“There are others that are looking at products ranging from processing of lithium, improving efficiency and extraction and processing of elements like nickel and cobalt, and then even looking at production of cathodes and anodes and battery cells.”

As part of Trailblazer, Wang said UQ is collaborating with industry to enhance battery materials.

One aspect of Curtin's Trailblazer approach, according to McDougall, will be incentivizing academics to collaborate more closely with industry — for example, through promotional schemes or revenue-sharing initiatives — to“make sure that they can share an upside if there’s any benefit that results from practical implementation of technology developed in those areas”. 

Another aspect will include “working with industry on delivery of course content to give a more applied experience for students, so they understand what the career pathway looks like and can move more seamlessly into those career pathways”. 

While the program will provide a considerable financial boost to commercialization efforts, McDougall believes that human resources are also needed.

“We certainly have high hopes that it will provide the resources that we need but one of the challenges we’re going to have will be recruitment of skilled people that are needed to provide a flow through of people from the university into industry,” he added.

He suggested people who are interested in the program should “get in touch with us, because we’re going to be looking for people”.