Application Notes - Magnetic Resonance

Using in-situ EPR Imaging to Analyse Metallic Deposits in Lithium-ion Batteries

To meet the growing demand for energy storage, advanced measurement techniques are used to improve secondary battery performance.

As global demand for more efficient batteries increases, lithium (Li) ion batteries (LIBs) are being ever more widely used, thanks to lithium’s high energy density and electrochemical potential.

LIBs and other rechargeable batteries are however limited by the phenomenon of dendrite growth – the accumulation of metallic Li deposits in a process known as ‘plating’. Li dendrites can build up over the battery’s lifetime, not only impacting its performance, but potentially causing it to short-circuit if the dendrite pierces the electrical separator.

Researchers developing the next generation of LIBs need to better understand the microstructural characteristics of dendrites, growth mechanisms, and the plating/stripping process. To do this, they are turning to advanced in-situ measurement techniques, including nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) spectroscopy, and imaging techniques such as magnetic resonance imaging (MRI).

In this app note, we summarise work by researchers from the Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, China, in which they recorded the semiquantitative distribution of Li deposits on the electrode plane at different plating and stripping stages via in situ spatial−spatial EPR imaging (EPRI). Spectral-spatial EPRI was also carried out, to estimate the Li microstructural dimensions at different deposition sites and operando EPR spectra were obtained to characterize plating/stripping behaviour. This study demonstrates an effective strategy, using an anode-free LIB, for investigating the plating and stripping behavior of metallic Li using in-situ EPRI.

Bruker’s solution portfolio for battery research, product innovation and quality control incorporate EPR and NMR instruments ranging from easy-to-use benchtop devices to highly sophisticated floor-standing systems.