Investigating the Impact of Various Binder Contents and Compression on Graphite Single-Electrode Dilatometry Measurements

Knowledge about how particle volume changes impact the electrode thickness and microstructural properties like porosity, especially as a function of binder types and contents, is crucial to improving battery design. Single-electrode electrochemical dilatometry provides insights into electrode thickness change during operation. However, commercially available setups have yet to be able to apply sufficient pressure on electrodes to replicate conditions in commercial batteries. This work aims to incorporate a wave spring washer into a commercially available single-electrode electrochemical dilatometer to apply additional force onto the working electrode. Using this setup, the impact of the binder composition on electrode thickness change was investigated using graphite electrodes with different amounts and ratios of styrene-butadiene rubber and carboxymethyl cellulose. It was shown that the electrode volume change is consistently lower than that of the crystallites as obtained by X-ray diffraction in the literature. It is further demonstrated that irreversible thickness change decreases with increasing binder content, indicating that a higher binder content helps prevent particle restructuring during cycling. Lastly, the modified setup exhibits significantly higher reliability than the commercial setup with low pressure, which we relate to electrode bending during lithiation.