There's a near endless list of things in automotive drivetrain technology that have changed since 1930. Oddly, the way scientists think about at how lithium-ion movement affects the performance of batteries is not one of them. Of course, not a lot of people were thinking about battery-electric drivetrains 80 years ago (the original battery-electric car era was long gone and gas-powered vehicles were the standard), but there is a lesson here.

Since the days of Herbert Hoover, scientists have essentially tied the performance of lithium iron phosphate batteries to how fast lithium ions can move from the liquid electrolyte to the solid electrode. The belief was based on what's called the Butler-Volmer equation and the details are a bit obtuse for chemistry-challenged reporters. More recently, however, a Japanese researcher using what's called the Marcus-Hush-Chidsey theory tied battery performance to how fast electrons move between the porous electrode and its carbon coating, Scientific American says, citing the journal Nature Communications. The key lines in the Scientific American report are the following:
  • "Researchers will therefore have to include electron transfer rates in their models for batteries or else real-world performance won't line up with simulations."
  • "Understanding the fundamentals better could one day unlock major performance gains in batteries" that "would enable a suite of clean technologies from grid batteries to smooth out power variations from wind turbines and solar panels to zero-emissions vehicles."
The research was spearheaded by Peng Bai, a postdoctoral associate at MIT, who found that the greater the battery voltage, the more important the electron-transfer rate becomes, meaning that this applies all the more to larger batteries. So while it remains to be seen how such a discovery will effect battery-electric drivetrain technology moving forward, the discovery may be a substantial one. It's unlikely we'll have to wait 80 years to find out.

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