As the world strives to reduce its reliance on fossil fuels, next-generation batteries will play a key role. With the right batteries, we’ll be able to store renewable power generated by the sun and wind, evening out the peaks and valleys of energy production and consumption. We’ll be able to equip electric cars with safer, longer-lasting batteries to enable motorists to drive long distances on a single charge, and then recharge these batteries more quickly. And we’ll be able to operate portable consumer electronics equipment from phones to computers to watches for longer periods of time without having to stop and recharge them.
Accomplishing these goals requires innovations in materials science, and many universities and businesses around the globe are leading the way. One of the centers focusing on cutting-edge battery research is the University of California at San Diego, where researchers at the Sustainable Power and Energy Center are exploring using new materials to achieve battery breakthroughs. As their scientists conduct research, they’re turning to electron microscopy to explore the interactions between materials at the nanometer level to obtain a better understanding for why batteries degrade over time.
The way lithium-ion batteries work is simple: a lattice of graphite filled with lithium ions forms the anode, and an oxide forms the cathode that’s connected to the opposite terminal. The anode and cathode are separated by a liquid electrolyte that allows ions to flow from the anode to the cathode as the battery discharges, and back again from the cathode to the anode as the battery is being recharged.
In a lithium-ion battery, ions flow from the anode to the cathode separated by a liquid electrolyte as the battery discharges energy.
The quest for longer-lasting, higher energy density batteries
Researchers at UC San Diego are changing up the materials used in different parts of the battery with the goal of producing safe batteries that hold more energy, last longer, and continue to perform under severe weather conditions.
One area of research involves improving the energy density of the lithium-ion battery by adding silicon to the anode. The capacity of silicon is an order of magnitude larger than that of graphite, which could increase overall battery energy density increase of approximately 10 percent to 15 percent. Unfortunately, silicon anodes aren’t ready for commercialization because designing reversible silicon electrode structures has presented researchers with difficult engineering challenges. By examining how silicon particles degrade during cycling at the nanoscale level, researchers are working to design electric vehicle batteries that can store more energy per volume.
Building a battery that operates at sub-zero temperatures
Another area of research involves the development of a battery that continues to function at sub-zero temperatures. By replacing the liquid electrolyte with the liquified gas, fluoromethane, researchers were able to create a battery that operates in temperatures as cold as -76° F, compared to -4° F for lithium-ion batteries. The researchers used several methods for materials characterization including a scanning electron microscope and FTIR. The new battery, which led the creation of the business, South 8 Technologies, makes it possible to operate electric cars in extreme cold conditions. It is also expected to lead to advances in ocean and space exploration.
These are just a few ways in which electron microscopy is helping to advance battery research.
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Herman Lemmens, PhD, is a Business Development Manager, Industry at Thermo Fisher Scientific.