Application of Inelastic Neutron Scattering to Understand Lignosulfonate Stability and Lead Battery Failure Mechanisms

The purpose of this research was to leverage inelastic neutron scattering to evaluate the stability and persistence of lignosulfonates in lead battery negative electrodes, and establish the technique for enabling the rational, hypothesis-driven approach to designing next-generation battery organics.
2V flooded lead batteries were prepared and tested per SAE J537 followed by the Dynamic Charge acceptance test of ILNAS 50342-6 and 17.5% DoD endurance in cycle test. Negative electrodes were harvested following formation, prior to the 17.5% DoD endurance test, and at end of life. Grids were analyzed on inelastic neutron spectrometers VISION (Spallation Neutron Source, Oak Ridge National Laboratory, USA) and MAPS (ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, UK). Peak intensity was used to quantify the lignosulfonate retained in the negative electrode, while concentrations in the electrolyte were determined through UV-vis spectroscopy.
Low-energy spectra (VISION) displayed dramatic changes in peak intensity as the electrodes evolved during testing. Initially interpreted as indicating dynamic lignosulfonate migration between negative electrode and electrolyte, this was disproven UV-vis studies. These features are putatively due to formation of lead hydroxide moieties either in situ or during harvesting.
High-energy spectra (MAPS) revealed a definitive feature attributable to the C-H bonds of the organic expander. Surprisingly, we measured no meaningful differences in the C-H feature intensity between the electrode samples, indicating the lignosulfonate concentration remains unchanged in the electrode throughout the life of the battery.
This finding thus contests a historical assumption about lead battery failure and suggests lignosulfonate decomposition is not a root cause of negative electrode sulfation.
Future work includes evaluating stability of additional organics, as well as electrodes that have failed under conditions known to accelerate sulfate formation. Additional experiments should also be performed to understand the interfacial behavior of the organic and its stability.
Keywords: Lignosulfonate, Vanisperse, Sulfation, Negative, NAM

Presenters

Dr Carter Abney

Technical Application Manager, Borregaard

Carter W. Abney earned B.S. degrees in chemistry and theoretical mathematics from the University of Wisconsin in 2005, and a M.S. degree in chemistry from the University of North Carolina in 2007. In 2015 he earned a Ph. D. in Inorganic Chemistry from the University of Chicago. From 2015 – 2018 he worked at Oak Ridge National Laboratory as the Eugene P. Wigner Fellow, using synchrotron x-rays and neutron scattering techniques to research the effects of metal coordination on polymer morphology and physicochemical properties. From 2018 – 2021 he worked at ExxonMobil Research & Engineering Company, developing new materials for CO2 capture and chemical separations. In 2021 he joined Borregaard USA as a Research Associate in their Biopolymers Division, researching lignosulfonate additives for lead and lithium batteries. He now serves as the global technical application manager over battery programs.
Carter has published 48 peer-reviewed journal articles, 15 patents and applications, and has received awards and recognitions including the ExxonMobil Global Technology Award, the ACS Industrial & Engineering Chemistry Division Early Career Fellow, the I&EC Research 2017 Class of Influential Researchers, a UT-Battelle Research Accomplishment award, and recognition from the US Department of Nuclear Energy for Innovations in Fuel Cycle Research.