Magnetic Resonance Imaging of Batteries

The design and development of improved batteries and energy storage devices requires understanding of the electrochemical reactions, transport and concentration gradients within these devices during operation. However, there are few methods that are able to visualise and quantify these spatially, in situ and in real time. Magnetic resonance imaging (MRI), a technique typically associated with medical research and diagnosis, has proven to be an excellent tool for non-invasively studying complex, spatially heterogeneous chemical systems in materials, engineering and chemical research1. While MRI has enormous potential for in situ investigation of the spatial distribution, speciation, and mobility of molecules and ions in electrochemical devices, there are currently very few examples of MRI being used to probe such systems. This is largely due to the experimental challenges associated with setting up an electrochemical cell inside a strong magnetic field and the imaging artefacts caused by the presence of metals that lead to undesirable variations in the radiofrequency (RF) and magnetic fields across the sample2. However, recent work3 has shown that such issues can be overcome and that it is possible to collect viable, quantitative, in situ data for the electrolyte near metal electrodes. Using MRI, the molecular transport and zinc and oxygen electrochemistry in an alkaline electrolyte have been investigated in a model Zn-air battery. Magnetic resonance relaxation maps of the electrolyte are used to visualise the chemical composition and electrochemical processes occurring during discharge. This paper will also review the challenges and opportunities MRI offers for the investigation of batteries and other energy storage devices. References [1]       M. M. Britton, Chem. Soc. Rev. 2010, 39, 4036-4043. [2]       M. M. Britton, Chemphyschem 2015, 15, 1731-36. [3]       M. M. Britton, P. M. Bayley, P. C. Howlett, A. J. Davenport, M. Forsyth, J. Phys. Chem. Lett. 2013, 4, 3019–3023.; A. J. Davenport, M. Forsyth, M. M. Britton, Electrochem. Comm. 2010, 12, 44-47. . Figure 1