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Sodium‐ion batteries are becoming an increasingly important complement to lithium‐ion batteries. However, while extensive knowledge on the preparation of Li‐ion batteries with excellent cycling behavior exists, studies on applicable long‐lasting sodium‐ion batteries are still limited. Therefore, this study focuses on the cycling stability of batteries composed of Na3V2(PO4)3/C based cathodes and hard carbon anodes. It is shown that full‐cells with a decent stability are obtained for ethylene carbonate/propylene carbonate electrolyte and the conducting salt NaPF6. With cathode loadings of 1.2 mAh/cm2, after cell formation discharge capacities up to 92.6 mAh/g are obtained, and capacity retentions >90 % over 1000 charge/discharge cycles at 0.5 C/0.5 C are observed. It is shown that both, the additive fluoroethylene carbonate and impurities in the electrolyte, negatively affect the overall discharge capacity and cycling stability and should therefore be avoided. Remarkably, the internal resistances of well‐balanced and well‐built cells did not increase over 1500 cycles and 5 months of testing, which is a very promising result regarding the possible lifespan of the cells. The initial loss of active sodium ions in hard carbon remains a major problem, which can only be partially reduced by proper balancing. [ABSTRACT FROM AUTHOR]

For the development of a full‐cell battery system, typically appropriate cathodes and anodes are characterized within a half‐cell setup where a metal counter electrode is installed to gather data about the employed electrodes. Ultimately, the individual capacity loadings allow for suitable balancing of the anode to cathode capacity in the full‐cell. This approach seems rather unproblematic for lithium‐ion batteries. For sodium‐ion batteries, however, we show that the high reactivity of sodium metal strongly influences hard carbon‐based electrode measurements within sodium‐ion half‐cells. As hard carbon is considered state‐of‐the‐art anode material, the presented results have high impact on the development of sodium ion batteries. Specifically, we show that the type of electrolyte, as well as cell‐ and measurement‐setup are key factors for reliable sodium half‐cell measurements of hard carbon. The investigated hard carbon electrodes have a high active material loading of 7.2 mg/cm2 (with 93 % active material content) resulting in an areal capacity of 2.4 mAh/cm2, which represent application‐relevant conditions. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries are considered to be one of the most promising postlithium batteries on the verge of commercialization. The electrode processing is expected to be similar to lithium‐ion batteries. However, the producibility and material processing challenges of potential electrode materials for anodes and cathodes are poorly understood. For industrial electrode production, a deep understanding of the processing of electrode materials with different particle morphologies is of great importance. In particular, the correlation between the process conditions and the electrode properties needs to be investigated further to understand the complex interactions between the battery slurry materials, the binder system, the drying process, and the microstructure formation. One promising anode material is hard carbon. The water‐based processing of hard carbon slurries presented in this article shows that the drying behavior is strongly interconnected with the particle size and particle interactions in the drying electrode. This study shows that all the hard carbons investigated do not exhibit binder migration at moderate drying rates. Even at very high drying rates (9 g m−2 s−1, 12 s drying time), an increase in adhesion force of up to 39% is observed for comparatively smaller particles compared to the adhesion force at lower drying rate. [ABSTRACT FROM AUTHOR]

Understanding and reducing edge elevations at the lateral edges are crucial aspects to reduce reject rates during electrode production for lithium‐ion batteries (LIB). Herein, different process conditions to reduce edge elevations at the lateral edges of water‐based, shear‐thinning coatings in the production of LIB electrodes are presented. The reduction of edge elevations is transferred from state‐of‐the‐art electrodes to high‐capacity electrodes. The developed process configuration greatly reduces reject caused by cutting off the edge areas in the industrial roll‐to‐roll process for electrode production. Compared with state‐of‐the art electrodes, the reject rate for high‐capacity electrode production is significantly higher because the edge geometry in crossweb direction of the electrodes is wider. An optimization can be achieved by a combined adjustment of the coating gap and the slot‐die angle to the substrate (angle of attack) to affect the pressure field in the coating bead. Therefore, a systematic investigation and optimization of these process parameters are presented. In addition, the investigation of the process stability of the coating is required. Based on this optimization, a reduction of edge elevations for high‐capacity electrode coatings (5 mAh cm−2) of 69% and ultrathick high‐capacity electrode coatings (7 mAh cm−2) of 48% is possible. [ABSTRACT FROM AUTHOR]