ABSTRACT
Femtosecond ultrafast-laser micro-patterning was employed to prepare a three-dimensional (3D) structure for the tape-casting Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode. The influences of laser structuring on the electrochemical performance of NMC811 were investigated. The 3D-NMC811 cathode retained capacities of 77.8% at 2 C of initial capacity at 0.1 C, which was thrice that of 2D-NMC811 with an initial capacity of 27.8%. Cyclic voltammetry (CV) and impedance spectroscopy demonstrated that the 3D electrode improved the Li+ ion transportation at the electrode-electrolyte interface, resulting in a higher rate capability. The diffusivity coefficient DLi+, calculated by both CV and electrochemical impedance spectroscopy, revealed that 3D-NMC811 delivered faster Li+ ion transportation with higher DLi+ than that of 2D-NMC811. The laser ablation of the active material also led to a lower charge-transfer resistance, which represented lower polarization and improved Li+ ion diffusivity.
ABSTRACT
The success of labs- and organs-on-chips as transformative technologies in the biomedical arena relies on our capacity of solving some current challenges related to their design, modeling, manufacturability, and usability. Among present needs for the industrial scalability and impact promotion of these bio-devices, their sustainable mass production constitutes a breakthrough for reaching the desired level of repeatability in systematic testing procedures based on labs- and organs-on-chips. The use of adequate biomaterials for cell-culture processes and the achievement of the multi-scale features required, for in vitro modeling the physiological interactions among cells, tissues, and organoids, which prove to be demanding requirements in terms of production. This study presents an innovative synergistic combination of technologies, including: laser stereolithography, laser material processing on micro-scale, electroforming, and micro-injection molding, which enables the rapid creation of multi-scale mold cavities for the industrial production of labs- and organs-on-chips using thermoplastics apt for in vitro testing. The procedure is validated by the design, rapid prototyping, mass production, and preliminary testing with human mesenchymal stem cells of a conceptual multi-organ-on-chip platform, which is conceived for future studies linked to modeling cell-to-cell communication, understanding cell-material interactions, and studying metastatic processes.
ABSTRACT
Thermal behaviour and thermophysical properties of two typical cathodes for lithium-ion batteries were studied in dependence of temperature. The cathode materials are composite thick films containing a mixture of 90 wt% LiMeO2 active material (with Me = Co or Me = Ni + Mn + Co, respectively) and additives (binder and carbon black), deposited on aluminium current collector foils. The thermal conductivity of each cathode type and their corresponding composite layers were determined up to 573 K from the measured thermal diffusivity, the specific heat capacity and the estimated density based on metallographic methods and structural investigations. In addition, the impact of lithiation degree x in LixMeO2 on the transport properties of cathode samples was also investigated. The quantitative determination and the homogeneity of Li content on the surface and within the bulk of the samples were validated by laser induced breakdown spectrometry. The results presented here explain at cell component level, i.e. cathode material, the thermal runaway behaviour of lithium-ion batteries in a combined approach of application oriented and fundamental research. Therefore, these data are significant for improving the simulation studies of their thermal management, in which the bulk properties are assumed, as a common approach, temperature and lithiation degree independent.
