Scientists have developed new technologies that could reduce the cost of recycling lithium iron phosphate batteries by 80% to 90%

Most lithium batteries now use a rare and expensive metal called cobalt as part of the cathode, but mining the material comes at a huge environmental cost, foreign media reported.One of the greener alternatives is called lithium phosphate, and a new breakthrough could further improve the environmentally friendly properties of the cathode material, which can be returned to its original state once used up, using only a fraction of the energy used in current methods.

The research, carried out by nanoengineers at the University of California, San Diego, focused on recycling cathode batteries made from lithium iron phosphate.By ditching heavy metals such as nickel and cobalt, these types of batteries can help avoid the degradation of landscapes and water sources where these materials are mined, as well as the exposure of workers to dangerous conditions.

Growing awareness of cobalt-related issues has helped transform the industry, with many looking for alternative battery designs, including big companies like IBM and Tesla, which started selling the Model 3 this year with lithium iron phosphate batteries.These batteries are safer, last longer and cost less to produce, but have the downside of being expensive to recycle once used up.

"It's not cost-effective to recycle them," said Chen Zheng, a professor of nanoengineering at the University of California, San Diego."It's the same dilemma as plastic -- the materials are cheap, but the way to recycle them is not."

The recovery breakthrough focuses on several mechanisms behind the degradation of lithium iron phosphate batteries.As they are recycled, this process drives structural changes, creating gaps in the cathode as lithium ions are lost, and iron and lithium ions exchange places in the crystal structure.This traps lithium ions and prevents them from circulating in the battery.

The team took the commercially available lithium iron phosphate cell and depleted it to half its storage capacity.They then took the batteries apart and soaked the resulting powder in a solution of lithium and citric acid, then washed it clean, dried it and heated it to about 60 to 80 degrees Celsius.The powder was then made into new cathodes and tested in button and pouch batteries, and the team found that its performance was restored to its original state.

This is because the recycling technology not only replenishes the battery's lithium ion stock, but also allows lithium and iron ions to return to their original positions in the cathode structure.This is due to the addition of citric acid, which provides electrons to the iron ion, reducing the positive charge that would normally repel the iron ion from moving to its original position.The result of all this is that the lithium ions can be released and recycled back into the battery.

According to the team's research, its technology uses 80 to 90 percent less energy and emits about 75 percent less greenhouse gases than current methods for recovering lithium-ion phosphate batteries.While this is a good start, the team says further research is needed to determine the overall environmental footprint of collecting and transporting large amounts of these batteries.

"Figuring out how to optimize these processes is the next challenge," Mr. Zheng said."This will bring the recycling process closer to industry adoption."

The study was published in the journal Joule.