The world is expected to experience a surge in battery demand as it moves to renewable energy sources. And, with the development of sustainable energy technologies, there will be a subsequent increase in the demand for precious metals used in batteries. Many of the materials used in such batteries, like lithium-ion batteries, are not available in abundance, and the best way to meet this need is to recycle old batteries.
To aid in this mission, a team of researchers at Rice University in the United States of America has developed a new recycling process that helps salvage more than 98 percent of the metal used in such batteries. The new approach not only drastically reduces secondary waste streams from the polluted, acidic leaching solutions but also drastically shortens the time required for recycling.
The details regarding their study are published in the journal Science Advances.
Joule-heating process
The team subjected the combined cathode and anode waste of batteries to heat or "flash" using the company's patented joule-heating method to temperatures beyond 2100 degrees Kelvin, achieved in seconds.
The method can remove the inert layer from battery metals, reduce their oxidation state, and make them soluble in low-concentration acid. According to researchers, no matter the chemistries of the batteries, all of the metals can be recovered with excellent yields using even weak acids like 0.01 M HCl, which reduces the amount of secondary waste. The process can achieve 98 percent efficiency in retrieving metals present in the recycled materials.
Compared to conventional methods, the new process takes less than 20 minutes to dissolve the same quantity. This process can potentially lessen the cost of recycling battery trash by using less energy, water, and acid and emitting less carbon dioxide.
“We developed a high-yield, low-cost method of reclaiming metals directly from ‘black mass’ ⎯ the combined cathode and anode waste the industry traditionally tries to recycle ⎯ that significantly reduces the environmental footprint of spent battery processing,” said Jinhang Chen, a chemistry graduate student at the University and co-lead author of the study, in a statement.
Role of recycling
The team suggests that battery recycling gains prominence as we have been driving electric vehicles for approximately ten years, and many of their batteries are approaching their end of life now. Recycling used batteries not only helps lessen the adverse effects of mining on the environment but is also a wise financial decision because many varieties of lithium-ion batteries contain higher concentrations of cobalt and nickel than natural ores.
Researchers say that even though the amount of electronic trash is growing at a 9 percent yearly pace, 95 percent of batteries are now not recycled because we cannot do so. “A lot of current battery recycling processes involve the use of powerful acids, and these tend to be messy, cumbersome processes," said James Tour, Rice’s T.T. and W.F. Chao Professor of Chemistry and Materials Science and nanoengineering.
The team using the new process can now easily filter out the required metals using low-concentration hydrochloric acid, which is utilized at a much lower quantity when compared to other recycling processes. This immensely helps to better the economics of the whole process.
“This study has the capacity to motivate the growth of battery waste management and contribute to the mass production of electrical vehicles at a more competitive cost by lowering the cost of battery production, said Chen.
Abstract
The staggering accumulation of end-of-life lithium-ion batteries (LIBs) and the growing scarcity of battery metal sources have triggered an urgent call for an effective recycling strategy. However, it is challenging to reclaim these metals with both high efficiency and low environmental footprint. We use here a pulsed dc flash Joule heating (FJH) strategy that heats the black mass, the combined anode and cathode, to >2100 kelvin within seconds, leading to ~1000-fold increase in subsequent leaching kinetics. There are high recovery yields of all the battery metals, regardless of their chemistries, using even diluted acids like 0.01 M HCl, thereby lessening the secondary waste stream. The ultrafast high temperature achieves thermal decomposition of the passivated solid electrolyte interphase and valence state reduction of the hard-to-dissolve metal compounds while mitigating the diffusional loss of volatile metals. Life cycle analysis versus present recycling methods shows that FJH significantly reduces the environmental footprint of spent LIB processing while turning it into an economically attractive process.
Originally published on Interesting Engineering : Original article