10.1021/acsaem.8b00608.s001 F. Jeschull F. Jeschull J. Maibach J. Maibach R. Félix R. Félix M. Wohlfahrt-Mehrens M. Wohlfahrt-Mehrens K. Edström K. Edström M. Memm M. Memm D. Brandell D. Brandell Solid Electrolyte Interphase (SEI) of Water-Processed Graphite Electrodes Examined in a 65 mAh Full Cell Configuration American Chemical Society 2018 SEI layer components binder materials polymer depletion counter electrode sodium carboxymethyl cellulose Solid Electrolyte Interphase CMC-Na electrolyte salt degradation ion migration SEI composition Water-Processed Graphite Electrodes Examined water-processed graphite electrodes PES 11 nm photoelectron spectroscopy Cell Configuration Electrode binders binder impact 65 mAh surface concentration surface layer SBR NMP SEI layer thickness SEI thickness correlates pilot scale sodium salt deposits LiFePO 4 PAA-Na component production costs 2018-09-05 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Solid_Electrolyte_Interphase_SEI_of_Water-Processed_Graphite_Electrodes_Examined_in_a_65_mAh_Full_Cell_Configuration/7098770 Electrode binders, such as sodium carboxymethyl cellulose (CMC-Na), styrene–butadiene rubber (SBR) and poly­(sodium acrylate) (PAA-Na) are commonly applied binder materials for the manufacture of electrodes from aqueous slurries. Their processability in water has considerable advantages over slurries based on <i>N</i>-methylpyrrolidone (NMP) considering toxicity, environment and production costs. In this study, water-processed graphite electrodes containing either CMC-Na:SBR, PAA-Na, or CMC-Na:PAA-Na as binders have been prepared on a pilot scale, cycled in graphite||LiFePO<sub>4</sub> Li-ion battery cells and analyzed post-mortem with respect to the binder impact on the SEI composition, using in-house (1486.6 eV) and synchrotron-based (2300 eV) photoelectron spectroscopy (PES). The estimated SEI layer thickness was smaller than 11 nm for all samples and decreased in the order: PAA-Na > CMC-Na:SBR > CMC-Na:PAA-Na. The SEI thickness correlates with the surface concentration of CMC-Na, for example, the CMC-Na:PAA-Na mixture showed signs of polymer depletion of the PAA-Na component. The SEI layer components are largely comparable to those formed on a conventional graphite:poly­(vinylidene difluoride) (PVdF) electrode. However, the SEI is complemented, by notable amounts of carboxylates and alkoxides, whose formation is favored in water-based negative electrodes. Additionally, more electrolyte salt degradation is observed in formulations comprising PAA-Na. The choice of the binder for the negative electrode had little impact on the surface layer formed on the LiFePO<sub>4</sub> positive electrode, except for different contents of sodium salt deposits, as a result of ion migration from the counter electrode.