Scientists from Worcester Polytechnic Institute in the US have developed a method for recycling lithium-ion batteries, in which the new cells withstand approximately twice as many charge and discharge cycles as cells made with commercial materials.
The research was led by Professor Yan Wang and is published in the scientific journal Advanced Energy Materials. Unlike many existing technologies that focus primarily on the cathode, the team reprocessed both of the battery's main electrodes.
Both the cathode and anode were recycled
The researchers converted low-nickel cathode materials from used batteries into NMC622 - a higher-performance material. In parallel, they purified and upgraded graphite extracted from old batteries to use as an anode material.
They then fabricated full-stack cells in which both the cathode and anode were made from recycled materials. In tests, these cells showed fewer side chemical reactions and approximately twice as long cycle life.
After 2,590 charge and discharge cycles, the cells retained 70% of their original capacity. The team says the improved structure makes it easier for lithium ions to move around and limits the processes that gradually degrade battery performance.
What the technology could change
The results are important because of the growing amount of waste batteries from phones, computers, electric vehicles and energy storage systems. Instead of old cells being dismantled just to extract individual metals, the materials from them can be turned into components for new batteries with better performance.
“The general impression is that recycled material is not as good as virgin material“, Yang Wang told IEEE Spectrum in an earlier conversation about the team's work. The new study challenges that notion, although the results were obtained in laboratory tests.
The researchers' analysis shows that the process could allow for the reuse of more than 95 percent of the waste materials. The calculations also indicate a potential increase in profitability by 22.9%, a reduction in greenhouse gas emissions by 27% and a decrease in energy consumption by 29.4% compared to the comparison process.
These indicators are the result of analyses, not from industrial line operation. Before the technology can be widely applied, it must be tested on a larger scale and confirmed that the quality and long life of the cells are maintained in real production.
Sources: bgnes.com, spectrum.ieee.org