Cell design and chemistry of commercial sodium-ion battery cells

Commercially available 18650-type cylindrical sodium-ion battery (SIB) cells with a nominal capacity of 1.5 Ah are comprehensively investigated, yielding in-depth insights into the cell design, the chemical composition of the electrodes and the electrolyte composition. In addition, the performance of single electrodes as well as the complete cell as such – under both standard and harsher conditions – are investigated. The results reveal superior charge storage kinetics at the Na$_x$Ni$_y$FezMn$_{1-y-z}$O$_2$-based cathode and rather sluggish kinetics at the hard carbon negative electrode, while the analysis of the already formed interphase indicates the presence of functional additives in the organic carbonate-based electrolyte. As such, this study reports a multi-disciplinary approach to assess the most relevant characteristics of commercial(-type) cells from the macro-scale to the micro-scale.