Even when a device is turned off, its battery gradually loses its charge and eventually some of its capacity for storing energy. Scientists have now documented this aging process in next-gen lithium-metal electrodes.
Now scientists at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory have taken the first atomic-scale look at how this process, called «calendar aging,» attacks lithium-metal anodes, or negative electrodes. They discovered that the nature of the battery electrolyte, which carries charge between the electrodes, has a big impact on aging — a factor that needs to be taken into account when developing electrolytes that maximize a battery’s performance.
The study also revealed that calendar aging can drain 2-3% of a lithium-metal battery’s charge in just 24 hours — a loss that would take three years in a lithium-ion battery. Although this charge seepage slows over time, it quickly adds up and can reduce the battery’s lifetime by 25%.
«Our work suggests that the electrolyte can make a big difference in the stability of stored batteries,» said SLAC and Stanford Professor Yi Cui, who led the study with Stanford Professor Zhenan Bao. «This is something people haven’t really spent time looking at or using as a way to understand what’s going on.»
The research team described their results in Nature Energy today.
Lighter batteries for far-ranging cars
Like today’s lithium-ion batteries, lithium-metal batteries use lithium ions to ferry charge back and forth between the electrodes. But where lithium-ion batteries have anodes made of graphite, lithium-metal batteries have anodes made of lithium metal, which is much lighter and has the potential to store a lot more energy for a given volume and weight. This is especially important for electric vehicles, which spend a significant amount of energy lugging their heavy batteries around. Lightening their load could drop their cost and increase their driving range, making them more appealing to consumers.
Story Source: Materials provided by DOE/SLAC National Accelerator Laboratory. Original written by Glennda Chui. Note: Content may be edited for style and length.