Researchers Resolve Misunderstanding About How Some Lithium Batteries Function

In the push for batteries that store more energy and cost less, many researchers are chasing diminishing performance returns with exotic materials and chemistries, including lithium air, liquid metal and molten salt.  One of the problems is that scientists are still grappling with the fundamental physics behind batteries and are finding out that in some instances, they've been going about it all wrong.

The study found that the Butler-Volmer (BV) equation, usually used to describe reaction rates in electrodes, is inaccurate, especially at higher voltage levels.  Instead, a different approach, called Marcus-Hush-Chidsey charge-transfer theory, provides more realistic results — revealing that the limiting step of these reactions is not what had been thought.

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.  The findings also open up new paths for optimizing battery performance such as using nanoparticle structures.

Rudolph Marcus, a chemistry professor at the California Institute of Technology who was not involved in this research, described the report as "a big step forward, especially for nanotechnology."

Marcus' work on electron transfer reactions, which earned him the 1992 Nobel Prize in chemistry, formed the basis for the mechanisms outlined in Bai's study.  Understanding the fundamentals better could one day unlock major performance gains in batteries, according to Marcus.  This 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.

Researchers Resolve Misunderstanding About How Some Lithium Batteries Function