Measuring Electrolyte Salt Concentration Gradients in Lithium-Ion Batteries using Benchtop μ-XRF

The electrolyte salt’s concentration gradients formed during fast (dis)charging limit Li-ion battery power performance. As such, studying them is highly desirable for battery development. In this study, a benchtop μ-X-ray fluorescence (μ-XRF) instrument was used to track electrolyte salt concentrations during charge–discharge cycling of a Li-ion half-cell. We show that time-dependent mapping of the cell using the benchtop instrument can yield temporal and spatial resolution reaching an analytical quality comparable to the state-of-the-art synchrotron-based μ-XRF measurements. As such, this proof-of-concept shows the possibility of obtaining critical electrolyte concentrations without the need for synchrotron radiation.