The global demand for electrochemical energy storage has been drastically growing and the projections are a challenge for the entire value-chain of lithium ionlithium-ion batteries.^[1] The related challenges in feedstock supply and cost fluctuations waswere driving the research and development on sodium-ion batteries, a drop-in technology using much more abundant raw materials.^[2] First commercial SIB cells from HAKADI® Shenzhen Zhonghuajia Technology Co.,Ltd. were available in September 2023 for private users in Europe. The objective of this study is to safely disassemble commercially available sodium-ion batteries (SIBs) and analyse the cell components—cathode, anode, separator, and electrolyte—in terms of their material composition. In this work, two types of SIB cells from different manufacturers were disassembled, examined, and compared. Similar approaches have been pursued by Waldman et al. and Sauer et al.^[3,4] However, different cell types are investigated in the current study.

Given the varied nature of the cell components, a comprehensive characterisation requires multiple analytical techniques. After successfully opening the cells, the electrodes were initially measured for dimensions, weight, and thickness. Scanning Electron Microscopy (SEM) was employed to investigate the particle morphology and size of both the cathode and anode. Additionally, Energy Dispersive X-Ray Spectroscopy (EDX) was used to determine the elemental composition of the active materials of anode and cathode. The specific surface area of the active material powders was also analysed.

Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) enabled the determination of the thermal properties of the components. TGA allows for the assignment of characteristic weight losses to specific components, thereby enabling quantitative statements on material composition. DSC, in turn, allows for the identification of characteristic phase transitions associated with specific materials.

The analysis revealed very similar compositions at the material level for both cell types. Only in the electrolyte a difference was observed: one cell type contained three organic carbonates, while the other contained four organic carbonates. Intriguingly, the SEM data for the cathode demonstrated notable differences in particle size and morphology, despite both cathode active materials being composed of the same transition metal oxide, i.e., NaNi_0.33Fe_0.33Mn_0.33O₂.

The two cell types (SIB_A and SIB_B) displayed significant differences in cycling stability. SIB_B could be charged and discharged stably over several hundred cycles, while SIB_A lost nearly 10% of its initial capacity after approximately 20 cycles. These differences may stem from cell design, such as insufficient electrode contact or uneven coatings. Alternatively, the discrepancies in cycle stability could arise from material-level differences, such as electrolyte composition. The data obtained so far suggest that the differing cell performance observed may be linked to variations in particle size and morphology of the cathode active materials. These findings provide important insights into which material compositions, particle sizes, and morphologies may be advantageous for the further development of specific SIB cell components.