Polymer electrolytes
To manufacture solid state batteries, ion-conducting polymers are used instead of liquid electrolytes. This avoids flammable solvents in liquid electrolyte cells and improves stability at high temperatures. We are researching polymer electrolytes to improve the materials' ionic conductivity while maintaining stability.
Ion-conducting polymers may be used in place of traditional liquid electrolytes to make solid-state batteries. The solid-state construct effectively eliminates the safety hazard posed by the flammable organic solvents used in liquid-electrolyte cells and offers better high-temperature stability. The biggest challenge with polymer electrolytes is to improve the ionic conductivity of the materials while retaining a high mechanical stability.
New host materials
We work with developing new materials based on ion coordination by carbonyl groups, such as polycarbonates, polyesters and polyethers, to use as host materials in polymer electrolytes. The carbonyl groups offer weaker coordination that, e.g., the commonly utilized oxyethylene coordinating motif, leading to faster Li+movement in the material.
Transport mechanisms
In order to design better host polymers, we need to understand the ion transport mechanisms in detail. We use a combination of experimental (impedance spectroscopy, NMR spectroscopy, IR spectroscopy) and computational (molecular dynamics, DFT) techniques to gain insight into the molecular details of ion coordination and transport. With proper understanding of the phenomena that govern ion movement in the materials, we can also devise strategies to move towards more efficient transport mechanisms.
Figure: Movement of a Li+ cation (purple) through a poly(trimethylene carbonate) (PTMC) matrix simulated by molecular dynamics.
Solid-state batteries
The materials we developed are ultimately tested in prototype solid-state battery cells. We test both Li+- and Na+-conducting polymers in Li and Na cells. While one of the aims is to produce materials that allow for battery operation at room temperature, we also try to implement the polymer electrolytes in niches where they have a clear edge over their liquid counterparts, such as in batteries that operate at high temperatures or other extreme conditions.
Figure: Cycling of a polycarbonate material in a Na metal cell at 60 °C.
References
- Beyond PEO-Alternative host materials for Li+-conducting solid polymer electrolytes. https://uu.diva-portal.org/smash/record.jsf?pid=diva2:1262653
- High-performance solid polymer electrolytes for lithium batteries operational at ambient temperature. https://uu.diva-portal.org/smash/record.jsf?pid=diva2:867615
- Ion transport in polycarbonate based solid polymer electrolytes: experimental and computational investigations. https://uu.diva-portal.org/smash/record.jsf?pid=diva2:798456
- Restricted Ion Transport by Plasticizing Side Chains in Polycarbonate-Based Solid Electrolytes. https://pubs.acs.org/doi/10.1021/acs.macromol.9b01912
- Stable Cycling of Sodium Metal All-Solid-State Batteries with Polycarbonate-Based Polymer Electrolytes. https://uu.diva-portal.org/smash/record.jsf?pid=diva2:1354042
Cooperation partners
More information to come.
Contact
- If you have any questions regarding our research you are welcome to contact professor Daniel Brandell.
- Daniel Brandell