Materials scientists seek to develop better lithium (Li) metal batteries by improving structural stability and reducing dendrite formation that causes battery failure. It is well-known that instability at the metal electrode-electrolyte interface causes lithium dendrite growth, leading to short-circuiting and formation of inactive lithium. New electrolyte designs that control lithium deposition during cycling may solve these issues. Researchers are investigating liquid crystalline (LC) electrolytes under different conditions at MAX IV’s ForMAX beamline to determine whether these electrolytic materials are possible to align on demand. Successful results hold promise to propel the development of Li metal batteries as a next-generation power solution for electric vehicles and energy storage systems.
The study examines a foundational idea that the organised molecular structure and chemistry of LC electrolytes allow for ‘self-healing’ of the battery interfaces whereas conventional solvent-based liquid electrolytes fail. “LC electrolytes introduce an additional energy contribution for dendrite nucleation due to their strong anchoring energy and are therefore expected to supress the growth of dendrites from the electrode-electrolyte interface,” explained Owies Wani, study author and postdoctoral fellow at Aalto University. “Besides, due to their fluid nature, they can potentially flow into the crack formed in the interface upon cycling of the battery and thereby form a new healed interface.”
The experimental phase included structural measurements of sample LC electrolytes with small- and wide-angle X-ray scattering (SWAXS) at ForMAX beamline to look at colloidal and molecular processes with applied stimuli of shear force at different temperatures. A rheometer supplies the force to align the material structure from a polydomain to a monodomain, which potentially creates straight, directed channels for efficient Li ion transport in the battery, thereby boosting ionic conductivity.
The group carried out three simultaneous measurements: rheology, SWAXS and polarized light imaging. “This was instrumental to understand the dynamic shear induced alignment in our LC electrolytes at different length scales,” explained Wani.
Read more on the MAX IV website
Image: From left) Bin Zhao, Xiaodan Hong, Mario Bello Piedrahita, Maximilian Hagemann, Owies Wani, Patrice Rannou and Zhongpeng Lyu.
Credit: Owies Wani