A team of Grainger Engineering researchers have received a $3 million grant from the US Army Corps of Engineers Construction Engineering Research Laboratory (CERL). Under this grant, the team aims to create the underpinning science and technology required to enable solid-state rechargeable lithium batteries. Solid-state batteries (SSBs) are an emerging and promising battery type, but significant research and development is still needed before they can be adopted widespread.
The project, titled “Solid-State Rechargeable Lithium Batteries,” is being led by materials science & engineering professor and Materials Research Laboratory Director Paul Braun. It also includes David Cahill (MatSE), Elif Ertekin (MechSE), Jessica Krogstad (MatSE), Nicola Perry (MatSE), Daniel Shoemaker (MatSE) and Beniamin Zahiri (MRL).
Conventional rechargeable batteries have four main components: the anode (negative side), the cathode (positive side), a separator (preventing contact between the anode and cathode) and the electrolyte (a liquid solution that allows ions to move within the cell). SSBs work just like regular batteries but with a solid electrolyte which replaces the liquid electrolyte and the separator. The rechargeable batteries we use everyday store energy in a very efficient manner, in addition to having relatively long lifetimes and the capability to be recharged many times. SSBs, however, have the potential to offer considerable advantages.
“One of the motivations for working on solid-state batteries is that they may have a much longer cycle life, meaning that they’ll have less fade over time,” says Braun. “Another motivation is they can potentially be significantly higher in energy density. The combination of these advantages has motivated the considerable research in this space.”
Zahiri explains that much of the research into SSBs has focused on new solid electrolytes and less attention has been paid to how the cathode and the solid electrolyte interact within the cell. Understanding and controlling this interaction is one of the main goals of the proposal. The team has planned a set of tightly integrated research and development activities focused on the synthesis of solid electrolyte, the interface between solid electrolyte and electrode and the overall cell fabrication.
Further, one of the key outcomes of this program will be learning how to make SSBs in a way that researchers can better understand how and why their properties change over time. Braun says, “In a conventional battery today, you can look at the voltage and the voltage profile, and you can get a pretty good idea of the state of health of the battery. In SSBs, we can’t yet make such a correlation. It’s not easy to determine what’s happening inside the battery from a conventional electrical measurement.”
Having such a large team of diverse researchers will allow them to apply an all-inclusive design strategy since all aspects of battery design are coupled together. “In an SSB, there are ceramic elements and metals, changing crystal structures and corrosion-like side reactions. There are at least five or six different kinds of material classes and phenomena that are all interacting and changing in a single SSB,” Braun says. “It’s something that is difficult for any one group to properly investigate.”
Braun also highlights the unique collaboration between Illinois and CERL. He says, “CERL is in our backyard. That really sets this program apart from a typical federal grant because we can interact real-time with the CERL team and get their feedback. By doing this, we can understand their needs better and they can get to know all members of the research team, including the students.”