Not Sexy But Useful
Some of the most important scientific and technological breakthroughs are the invention of tools that allow you to make better tools, or to do research faster. The general public never sees these things, but it still reaps the benefits. A new technique to test electric car and hybrid car batteries more quickly might just be such a breakthrough, because it could allow engineers to know within weeks how a new battery chemistry performs instead of having to wait months or even years. A faster EV development cycle should drive down costs and increase the pace of innovation, and mean that fewer promising batteries will gather dust. Read on for more details on how this works.
The new testing equipment is based on very accurate measurements of the coulombic efficiency of the batteries being tested. By measuring the difference between the amount of charge that goes in and the amount that goes out, small unwanted reactions within the battery that would pose problems over time can be detected early.
Jeff Dahn of Dalhousie University] has built a battery-charging system that can detect very small losses of charge, identifying in a few weeks the presence of life-shortening reactions that otherwise wouldn’t show up until after months or years of testing. Dahn has used the technique to identify subtle changes in chemistry that can increase the cycle life of one type of battery up to sixfold.
Such accurate testing wasn’t necessary for lithium-ion batteries when they were used almost entirely for portable electronics that have to last only a few years. But now batteries are being designed to power electric vehicles or to store energy from solar panels, and they must last 10, 15, 20 years or longer. Over such spans, even a tiny inefficiency can lead to big problems. […]
With conventional measuring techniques, he says, “It’s hard to know whether a change you’ve made is good or bad without doing a test that’s longer than your career.” By accurately measuring coulombic efficiency, he says, “in a few weeks, you’ve got everything.
Of course, this technique isn’t without faults. It doesn’t tell you everything about what is going wrong in a battery, and we don’t know yet how effective it will be at predicting the “calendar life” of batteries (how long a battery will last on the shelf, which is different form the number of cycles it can handle), but it is a great new tool to have in the toolbox.