Quantum sensing of electric field distributions of liquid electrolytes with NV-centers in nanodiamonds

To understand the degradation of batteries with increasing cell age, it is necessary to understand the irreversible processes happening inside the liquid electrolyte in-situ and in-operando.

We propose to use nanodiamonds containing single NV-centers as label-free sensors [1] inside the liquid electrolyte of a battery [2]. From theoretical considerations we found out that variants of the Free-Induction-Decay (FID) allow to determine the mean electric field components, where we took into account how the electric field components act on the NV-centers ground state spin states. This allows us to derive three FID variations which have the ability to measure the mean electric field vector in the reference frame of the NV-center, if our pulse sequences are performed sequentially. In addition, we show that a specially designed pulse sequence based on three polarized π pulses enables to also measure the electric field fluctuations. Our proposed scheme therefore has the ability to fully reconstruct the electric field distribution inside the liquid electrolyte via nanodiamonds with a single NV-center. This not only allows to deduce local ionic concentrations but will also help to understand molecular processes inside the liquid electrolyte while the battery is being operated.

[1] R. P. Friedrich, M. Kappes, I. Cicha, R. Tietze, C. Braun, R. Schneider-Stock, R. Nagy, C. Alexiou, C. Janko, Optical Microscopy Systems for the Detection of Unlabeled Nanoparticles, International Journal of Nanomedicine 17, 2139-2163 (2022)

[2] M. Hollendonner. S. Sharma, S. K. Parthasarathy, D. B. R. Dasari, A. Finkler, S. V. Kusminskiy and R. Nagy, Quantum sensing of electric field distributions of liquid electrolytes with NV-centers in nanodiamonds, New J. Phys. 25 093008 (2023)