Lithium ion batteries (LIB) have become a cornerstone of the shift to electric transportation. In an attempt to decrease the production load and prolong battery life, understanding different degradation mechanisms in state-of-the-art LIBs is essential. Here, we analyze how operational temperature and state-of-charge (SoC) range in cycling influence the ageing of automotive grade 21700 batteries, extracted from a Tesla 3 Long Range 2018 battery pack with positive electrode containing LiNixCoyAlzO2 (NCA) and negative electrode containing SiOx-C. We used a combination of electrochemical and material analysis to understand degradation sources in the cell. Herein we show that loss of lithium inventory is the main degradation mode in the cells, with loss of material on the negative electrode as there is a significant contributor when cycled in the low SoC range. Degradation of NCA dominates at elevated temperatures with combination of cycling to high SoC (beyond 50%).

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In order to lower the energy consumption of the fibrillation stage for the pulp and paper industry, a new technology need to be innovated and developed. This paper presents an innovative new design of a venturi nozzle as a concept for refining pulp using hydrodynamic cavitation. The conditions created by cavitation bubbles collapsing near paper fibres are similar to the conditions in conventional refiners used in the pulp and paper industry. The cavitation created in the venturi implodes on the surface of the cellulose fibres, increasing the fibrillation and processing the fibres further. Cavitation is hard to control and can cause high mechanical wear, therefore an optimization study of the venturi nozzle is performed using Computational Fluid Dynamics (CFD) and state-of-the-art optimization techniques. Finally, the optimal venturi shape is investigated in a series of detailed numerical simulations, using a Bingham fibre model to include the effect pulp fibres has on the flow. The investigation shows that cavitation bubbles start to form at an outlet pressure of 1.87 bar, for an inlet pressure of 3.00 bar. The intensity of the bubble collapse depends on the surrounding pressure and this outlet pressure therefore enables a powerful treatment of the pulp fibres. In conclusion, the venturi concept is plausible and seems promising at this stage. More research, in particular physical experiments, is however required before a conclusive verdict can be given.

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