ADVANCING LITHIUM BATTERIES

BY DICK MORTON

The lithium-ion (Li-ION) battery is probably the most important technology today as it powers everything from phones to cars. Although, the lithium-ion battery has been around for decades, it’s taken research just as long to reach the capabilities we now have with it. Argonne National Laboratory is largely to thank for a majority of that research.

-Arturo Gutierrez, Assistant Materials Scientist

Argonne Labs started working on lithium-ion battery research back the mid 90’s. The research done here has been so impactful on Li-ION technology that three of their scientist, John B. Goodenough, M. Stanley Whittingham and Akira Yoshino, just won the 2019 Nobel Peace Prize in Chemistry. One of the most significant experiments was the one in which they used the APS (Advanced Photon Source) X-Ray Microscope to peer into a lithium battery at the molecular scale to visually see lithium move from the cathode to the anode. This gave researchers even greater knowledge to engineer processes and materials to better facilitate the action that once was considered only a theory.

While at Argonne Labs, Arturo Gutierrez, Assistant Materials Scientist of the Chemistry Department, took us through just how the Li-ION battery works, and how they are made.

“When it takes the lithium over to the graphite, it’s like ‘I don’t want to be a higher energy,” said Arturo, "I’m going to naturally go through the liquid, and get to a lower energy state.’ And that’s the spontaneous reaction that gives us power.”

A Li-ION battery may seem complicated, but it’s actually quite simple in design. The battery is made up of seven different materials. There is the metal casing that it is housed and sealed in, the cathode, anode, a plastic separator, a metal spacer, electrolytic solution, and a curved washer that serves as a spring.

The process of creating the cathode is the essential part of the research. It starts with mixing lithium-rich nickel, magnesium, and cobalt in powder form. The mixed powder is then baked in order to get the chemical structure just right. It is then mixed with a binding agent and conductive carbon to make a laminate. The cathode laminate, which is made into sheets, is then cut into tiny circles to fit into coin cell batteries.

In the lab, they make batteries inside of a large ‘glove-box’. Because moisture and oxygen have a negative effect on the process, a vacuum is pulled on the glovebox, and then filled with inert argon gas. The cathode is first placed into the metal housing of the battery. A plastic spacer, which is porous to allow the lithium ion to pass through, is then placed to separate the cathode from the anode. The spacer prevents the cathode and anode from touching which would short out the battery.

The anode is then placed on top followed by some electrolytic solution. A metal spacer and a spring-washer then are placed in to add pressure and prevent any shifting. Finally, the cap (which would be your negative side of the battery) is placed on top, the battery is placed into a special press, and sealed up for use.

Inside the battery, a very unique and special dance is performed. (See graphic below.) During charging, lithium ions leave the cathode structure and move to the anode. Lithium doesn’t like being at a higher energy state, but the anode keeps it there until power is discharged. At that point, the lithium gladly gives up it’s extra electrons and then moves back into the cathode where it waits until you plug your phone back in.

The issue is when the lithium leaves the cathode it also leaves an empty space. If the structure of the cathode breaks due to this empty space, the battery cannot hold the same charge it once used to, thus shortening the lifespan of the battery. Argonne is working to make a longer lasting , stronger Li-ION battery that will carry us into the future. ■

Parts listed in render from Top to Bottom: Cap (negative side); Spring Washer; Metal Spacer; Anode; Porous Plastic Spacer; Cathode; Battery Housing (Positive Side)