By Colton Poore
From laptops to electric vehicles, lithium-ion batteries power everyday life. However, as demand for longer-lasting devices threatens to outstrip the energy that lithium-ion supplies, researchers are on the hunt for more powerful batteries.
A team led by Kelsey Hatzell, an associate professor of mechanical and aerospace engineering and the Andlinger Center for Energy and the Environment, have uncovered insights that could help power a new type of battery, called an anode-free solid-state battery, past lithium-ion’s limitations.
By understanding how these advanced solid-state batteries operate and fail under different conditions, Hatzell’s research is informing efforts to improve their performance and manufacturability, helping them to move from the lab to the real world to support the clean energy transition.
“If we can successfully introduce these up-and-coming batteries, we can access energy densities that are impossible with conventional batteries,” said Hatzell. “It would mean that your laptop and your phone would last longer on a charge. It could allow electric vehicles to hit over 500 miles on a charge. It could even move us toward feats that seem impossible today, like electrified aviation.”
The papers stem from Hatzell’s involvement as the manufacturing leader for Mechano-Chemical Understanding of Solid Ion Conductors (MUSIC), an Energy Research Frontier Center supported by the U.S. Department of Energy whose members are unlocking fundamental insight to advance electrochemical energy storage systems. MUSIC is led by the University of Michigan at Ann Arbor and encompasses 16 faculty members from across nine institutions, including Princeton University.
“Solid-state batteries can revolutionize energy storage technology, but a significant challenge is developing a process for manufacturing them at scale,” said energy storage expert Jeff Sakamoto, director of MUSIC and a professor of materials and mechanical engineering at the University of California, Santa Barbara. “Hatzell’s work is playing an important role in improving the solid-state manufacturing process, and her work with MUSIC is an example of how integrated research approaches can help overcome complex, multidisciplinary challenges.”
Batteries: A look under the hood
Conventionally, batteries feature two electrodes — one positive (commonly called the cathode) and one negative (the anode). Each electrode is paired with a thin metal foil called a current collector that connects the battery to the external circuit, and the two electrodes are separated from one another by an electrolyte.
The movement of ions between the two electrodes powers the battery. When the battery charges, ions flow from the positive electrode, through the electrolyte, and to the negative electrode. When the battery is discharged, the flow of ions reverses directions.
Compared to the familiar lithium-ion battery, the batteries that Hatzell and her group study are different at two fundamental levels.
First, while the electrolyte in lithium-ion batteries is a liquid, the electrolyte in a solid-state battery is — as their name implies — a solid.
The difference is significant. Solid-state batteries can store more energy in less space than lithium-ion batteries, opening the door to longer driving ranges for electric vehicles. They can also operate with high performance at a wider range of temperatures and promise greater durability than their lithium-ion counterparts.
Second, the batteries that Hatzell studies are ‘anode-free,’ meaning that the negative electrode has been removed. Instead, ions flow from the positive cathode directly to the current collector at the opposite end of the battery. The ions then plate onto the current collector itself, forming a thin metal layer as the battery charges.
Removing the anode makes the battery cheaper and even more compact than standard solid-state batteries. At the same time, anode-free solid-state b
