Investigating the effect of different environments on NMC811 positive electrode precursors using ESEM and TGA-DSC

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Kemian tekniikan korkeakoulu | Master's thesis
Major Studies in Energy Storage
Degree programme
Master's Programme in Energy Storage
Lithium-ion batteries have been a focal point of extensive research and development for various applications, including stationary energy storage, portable electronics, and electric vehicles. Two central challenges addressed by research are mitigating capacity losses and enhancing safety features to ensure the reliability and performance of these batteries. Over the years, numerous battery chemistries have been explored, both theoretically and in industrial settings, aiming to meet these challenges. Notably, novel chemistries, such as Lithium-iron-phosphate (LFP), Lithium-rich manganese oxide (LMO) and Lithium Nickel Manganese Cobalt Oxide (NMC) batteries, have garnered attention. Among the different NMC ratios tested, LiNi0.8Mn0.1Co0.1O2 (NMC811) has emerged as a promising candidate, celebrated for its remarkable energy density resulting from increased capacity and a wider operating voltage range. However, recent research has uncovered that the presence of oxygen and excess moisture during the production process has been found to induce non-uniform morphologies in these materials which can potentially disrupt mass transport and influence the thermal behaviour of the battery components. Furthermore, it is essential to emphasize the role of unlithiated precursors in the quality and performance of the final lithiated battery materials. These precursors significantly impact various properties, including morphology, thermal stability, energy density, capacity, and cycle life. This investigation encompasses an extensive analysis of varying moisture content, temperature conditions, and gaseous environments. Thermal stability is assessed through Thermogravimetric Analysis (TGA) coupled with Differential Scanning Calorimetry (DSC), while morphological features are examined using Environmental Scanning Electron Microscopy (ESEM). These findings pave the way for innovative precursor studies, focusing on enhanced structural design to mitigate risks associated with high nickel content. Therefore, in this context, the present thesis successfully achieves its objectives by investigating the influence of diverse environmental conditions on unlithiated NMC811 positive electrode precursors.
Kallio, Tanja
Thesis advisor
Llanos, Princess Stephanie
lithium-Ion baltteries, ESEM, TGA-DSC, NMC811 precursors
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