Challenges and prospects of in situ nuclear magnetic resonance for electrochemistry devices

Understanding the electrochemical mechanisms in supercapacitors is key in the attempt to improve their performance to meet the current needs of energy storage devices. Electrochemical processes of interest are charge storage mechanisms and electrochemical reactions in electrodes, electrolytes, and at their interfaces. In situ characterization methods for electrochemical cells under operating conditions of charge and discharge have been advanced. Conventional in situ nuclear magnetic resonance (NMR) can be used to monitor the charge diffusion, transfer, or storage process; ions and solvent molecules can be separately observed and counted within nanopores. However, the technique has currently some draw-backs in identifying and measuring in-pore ions, and surface electrode morphologies as the NMR signal becomes weaker when the ions are stored during charging. Increased sensitivity and resolution in detecting ions in pores could be a relevant improvement for in-situ NMR. Here, we have put in perspective the possible role in improving the sensitivity of in-situ NMR by using diamond quantum sensors based on the nitrogen-vacancy centers and highlight foreseeable prospects and challenges in its application to monitoring local electric field changes in electrochemical devices in situ and during operations.(c) 2022 Elsevier Ltd. All rights reserved.