Investigation of Moisture Content, Structural and Electrochemical Properties of Nickel-Rich NCM Based Cathodes Processed at Ambient Atmosphere

Abstract

For batteries with high energy density and good fast-charge capability, NCM cathode active materials with ≥80 mol% nickel are promising due to their high specific capacities. Unfortunately, the increase in nickel content is accompanied by a high susceptibility to moisture. Therefore, nickel-rich NCM is coated or doped by the manufacturers to increase its stability. However, it is unclear if special requirements regarding ambient humidity must still be met during the whole production chain, or only after post-drying and during cell assembly. Therefore, the structure and properties of three different nickel-rich NCM active materials (one doped monocrystalline, two coated polycrystalline materials) processed at ambient atmosphere were investigated. At every process step, moisture content and microstructure were examined. Prior to cell assembly, two different post-drying procedures were applied and investigated. As validation, electrochemical tests were performed. Both polycrystalline cathodes demonstrated good physical and electrochemical properties, despite the ambient process atmosphere. Higher moisture reduction led to improved electrochemical performances at higher C-rates. Finally, a comparison between dry and normal atmosphere of the best performing material indicates that a production of high-quality nickel-rich electrodes at ambient atmosphere is possible if their exposure to moisture is short and well-designed post-drying techniques are applied.

Production of Nickel‐Rich Cathodes for Lithium‐Ion Batteries from Lab to Pilot Scale under Investigation of the Process Atmosphere

“…Furthermore, the calculation of the porosities of the conductive network, ε CN , shows that Ni‐rich_polyA (22.5%) has lower values than Ni‐rich_polyB (27.7%). This trend agrees with the results of Mayer and Huttner et al, [ 21 ] according to which a certain amount of the increased water uptake after calendering was attributed to an increased amount of pores in the electrode microstructure. After calendering, both cathodes show the expected water uptake.…”

“…A schematic illustration of this is presented in Figure 2b,c. Mayer and Huttner et al [ 21 ] observed the same phenomenon for cathodes containing different polycrystalline Ni‐rich NCM active materials. Hence, a higher moisture uptake of the cathodes after calendering was expected in the current study as well.…”

“…However, they confirm results obtained in a former study. [ 21 ] As a next step, the polycrystalline Ni‐rich NCM materials were processed within ambient atmosphere at pilot scale to verify good performance at a higher scale. Moreover, cathode properties were analyzed to obtain a deeper understanding of Ni‐rich cathode production.…”

Influence of Different Alginate and Carboxymethyl Cellulose Binders on Moisture Content, Electrode Structure, and Electrochemical Properties of Graphite‐Based Anodes for Lithium‐Ion Batteries

“…Increased capillary condensation and the different polymeric structures could have caused a higher moisture uptake of the ALG anodes before postdrying and an impeded moisture removal during postdrying. [21,48] As a consequence, the ALG anodes also showed higher moisture contents after postdrying. Furthermore, when comparing the CMC anodes, it can be observed that the anode with the CMC of highest molecular mass, namely CMC-A, contains more moisture.…”

A Perspective on Innovative Drying Methods for Energy‐Efficient Solvent‐Based Production of Lithium‐Ion Battery Electrodes

“…Therefore, Joule heating offers a possibility for the upscaling of lab-scale conductive electrode drying, which is commonly used during material development. [70][71][72][73][74][75] In contrast to conventional convective drying, the heat is mainly introduced from the current collector foil into the coating from below, possibly impacting the drying mechanisms that take place in the electrode coating. A hurdle for this approach is the challenge of maintaining continuous electrical contact between the current collector foil and the electrical wiring of the drier, which is necessary to enable coil-to-coil processes while ensuring an even current distribution in the current collector foil for homogeneous drying.…”