The detailed investigation of advanced battery electrolyte solution structure and dynamics is critical to the ongoing development and capability expansion of alternative battery technologies for grid storage. Fundamental studies inform the design of performance-enhancing electrolyte additives and optimal solvent composition. Herein, we propose research coupling multinuclear solution-state NMR and computational chemistry methods with the aim of working towards a thorough elucidation of the electrolyte solution structure in Pb-acid, vanadium redox-flow, and aqueous Zn-MnO2 battery systems. The results will contribute towards the resolution of key scientific questions regarding the efficacy of deep cycling, the thermal stability, and the intercalation mechanism, respectively, for these systems, which are candidates for inexpensive energy storage and grid applications. The Pb-acid results will be directly used to benchmark extracted electrolyte samples from commercial batteries, in order to probe the degradation over high-stress cycling. In addition to bulk electrolyte properties, the research will also explore the electrolyte-electrode interface for the Zn-MnO2 system by combining solid-state NMR and EPR measurements for cycled electrodes. The obtained results will have a significant impact in persistent scientific debate for this system regarding its commercial viability and future development.
The success of both the bulk and electrode interface approaches hinges on the availability of magnetic resonance resources capable of interrogating a wide range of nuclei (1H, 17O, 33S, 51V, 55Mn, and 67Zn), for spectral measurements (both in solution, and by solid-state NMR for 1H and 67Zn), relaxation (17O), and diffusivity (1H) studies over a wide range of temperatures. The complementary computational chemistry calculations of 17O NMR parameters, which serve as a versatile indirect probe of solution structure across the systems, will be performed using DFT on frames extracted from DFTB MD trajectories which mimic the solution distribution. In this way, a picture can be formed of the underlying molecular changes which yield evolution in the measured NMR spectra with changing solution conditions, particularly concentration. The necessary computational resources, in conjunction with the wide array of magnetic resonance tools required for these characterizations, are only available in the EMSL user facility, and studies of this scope are the most effective way to holistically examine the key scientific questions surrounding these battery systems.