Researchers Solve Mystery Behind Lithium Ion Batteries
Researchers have finally discovered how energy moves within a certain types of electrodes in cells, overturning the conventional school of thoughts that has reigned for more than 80 years.
Until recently, scientists grappled with the fundamental physics behind batteries and in some instances they found it to be all wrong.
Researchers based their models on the the Butler-Volmer equation which described how electrical currents respond to electrical potentials. The relationship was described in 1930 and around that time it confirmed the results. However, as new types of batteries started evolving, the relationship started turning out to be an obsolete.
The lead researchers of the study said the idea piqued when they came across a Japanese experiment on lithium iron phosphate cells. "The traditional Butler-Volmer equation did not fit [those] data," said Peng Bai, a postdoctoral associate at the Massachusetts Institute of Technology and the author of the study, according to Scientific American.
Although, lithium ion batteries have prevailed widely, it came as surprising that scientists didn't fully understand its behavior. "It's widely used in commercial batteries," Bai said. "This material has been investigated by more than 2,000 papers."
In their analysis, researchers found that Butler-Volmer equation did not fit the results well. However an another model, the Marcus-Hush-Chidsey theory matched the output. The Marcus-Hush-Chidsey theory explained how fast electrons moved between the porous electrodes.
"The difference is really at the high-voltage regime," Bai said. "In my paper, the difference kicks in at voltages larger than 100 millivolts."
The findings open up new paths for optimizing battery performance like using nano particle structures.
Rudolph Marcus, a chemistry professor at the California Institute of Technology who was not involved in this research, described the research as "a big step forward, especially for nanotechnology," as quoted by Scientific American.
"When it comes down to details for individual steps, individual processes, there is always room for improvement," Marcus added.
Researchers have outlined the understandings in the journal Nature Communications.