Search

LiNixMnyCozO2 (x+y+z=1) is one of the most present and versatile positive active materials for lithium ion batteries due to comparatively high specific capacity and high operating potential. However, NMC materials are prone to various degradation effects including moisture uptake, formation of impurities at the particle surface and transition metal dissolution during charge/discharge cycling and/or at elevated temperatures. Beyond that, cation mixing can lead to phase transformation, oxygen evolution, particle cracking and particle disintegration. Therefore, an alumina coating was applied and optimized as protective interphase on LiNi0.6Mn0.2Co0.2O2 (NMC622) powders, using a specifically in‐house developed RF‐magnetron sputtering technique. The alumina coated NMC622 showed a 13 % improvement in capacity retention after 200 charge/discharge cycles in lab‐scale cells, compared to pristine uncoated NMC622. Using electrochemical impedance spectroscopy, the interfacial/interphasial resistance of pristine and alumina coated NCM622 based electrodes were explored to study the impact of the coating on lithium ion transport. Furthermore, the structural and thermal stability of cyclic aged NMC622 were analyzed via TEM, EELS and TGA. Therein, alumina coated samples demonstrated enhanced thermal stability, less structural degradation, and reduced particle cracking. [ABSTRACT FROM AUTHOR]

The drying of electrodes for lithium-ion batteries is one of the most energy- and cost-intensive process steps in battery production. Laser-based drying processes have emerged as promising candidates for electrode manufacturing due to their direct energy input, spatial homogeneity within the laser spot, and rapid controllability. However, it is unclear to what extent electrode and cell quality are affected by higher heating and drying rates. Hybrid systems as a combination of laser- and convection-based drying were investigated in an experimental study with water-processed LFP cathodes. The manufactured electrodes were compared with purely laser-dried and purely convection-dried samples in terms of drying times and quality characteristics. The electrodes were characterized with regard to physical properties like adhesion and electronic conductivity, as well as electrochemical performance using the rate capability. Regarding adhesion and electronic conductivity, the LFP-based cathodes dried in the hybrid-drying process by laser and convection showed similar quality characteristics compared to conventionally dried cathodes, while, at the same time, significantly reducing the overall drying time. In terms of electrochemical performance, measured by the rate capability, no significant differences were found between the drying technologies used. These findings demonstrate the great potential of laser- and convection-based hybrid drying of LFP cathodes to enhance the electrode-drying process in terms of energy efficiency and operational costs. [ABSTRACT FROM AUTHOR]

In modern electrode manufacturing for lithium-ion batteries, the drying of the electrode pastes consumes a considerable amount of space and energy. To increase the efficiency of the drying process and reduce the footprint of the drying equipment, a laser-based drying process is investigated. Evaporation rates of up to 318 g m−2 s−1 can be measured, which is orders of magnitude higher than the evaporation rates in conventional furnace drying processes. Optical measurements of the slurry components in the visible and near-infrared spectrum are conducted. Thermal analyses the of laser-dried samples reveal that the commonly used binders carboxymethyl-cellulose (CMC) and styrene–butadiene rubber (SBR) are not affected by the laser drying process within the investigated process window. The results indicated that with the combination of a fast laser drying step and a subsequent convection drying step, high evaporation rates can be achieved while maintaining the integrity and adhesion of the anode. [ABSTRACT FROM AUTHOR]

Drying electrodes is very cost-intensive as it is characterized by high energy and space consumption. Laser drying is considered a promising alternative process due to direct energy input and lower operating costs. However, it is unclear whether the same product and process quality can be achieved with laser drying. Silicon–graphite anodes with different silicon contents were processed using either a high-power diode laser or a convection oven. The laser-drying process was investigated using thermography, and the effect of laser drying on the electrode quality was examined using adhesion and residual moisture measurements. Furthermore, thermogravimetric analysis, SEM images and electrical conductivity were used to analyse the laser- and convection-dried anodes. It was shown that silicon–graphite anodes can also be manufactured using laser drying, with a significant reduction in drying time of over 80%. [ABSTRACT FROM AUTHOR]