EV Batteries Lasting Longer Than Expected, Stanford says

A commonly held perception about lithium-ion batteries used in electric vehicles and hybrids may not be true according to a Stanford University study that shows the batteries lasting longer than earlier lab tests had shown.

In a paper published on December 9th, researchers from the SLAC-Stanford Battery Center and the SLAC National Accelerator Laboratory monitored differences in battery health when the batteries were subjected to two types of battery charge and discharge cycled. 

The most commonly used method of lab testing batteries involves charging and discharging the batteries using a constant current. Another more involved test, called Dynamic Cycling, mimics real-world activity more closely with surges in use followed by rest and regeneration cycles. 

The researchers found that the batteries subjected to the dynamic cycle test fared better in in health metrics such as the degradation of electrodes and lithium.

The team tested four charge-discharge patterns to 92 sample batteries over two years and found that the closer to real world use the pattern was, the better the health results of the battery at the end of the test with up to a 40 percent improvement over the standard test.

The results were unexpected because the researchers thought rapid changes in charge-discharge in the dynamic cycling test would cause faster degradation of the battery components. 

Fear of expensive battery replacement costs had impacted the adoption of electric vehicles despite the likelihood that they will last 12 years or more.