Using XRS to probe speciation of lithium cations for battery electrolytes

Lithium-ion batteries already play a crucial role in energy storage, but there is still plenty of room for improvement in performance. There is a lack of knowledge about the structure of the solvent/anions around the Li+ in solution, mainly due to a lack of available techniques to study Li+ speciation. We propose to overcome this challenge by using X-ray Raman scattering (XRS) at the Li K edge at ID20 to validate our calculations, from which we will then be able to identify the coordination number around Li+ in solution. We will study a wide variety of electrolytes, allowing us to demonstrate that our approach is viable for both already commonly used electrolytes (e.g. Li[PF6] in carbonate solvents) and novel electrolytes that have the potential to overcome some traditional problems with commonly used electrolytes (e.g. ionic liquids).