Development of a solid-state battery model to predict the macroscale behavior for automotive applications

As the vehicle industry grows increasingly devoted to sustainable mobility, hybrid-electric propulsion systems with batteries with enhanced gravimetric energy density and cyclability qualities have drawn a lot of attention. In this setting, the widely established lithium-ion battery technology, despite providing decent performance, has partially attained a certain limit. The battery market is thus exploring new technologies capable of strengthening battery electric vehicle safety and overall life cycle assessment. Under such circumstances, the all-solid-state battery (ASSB) appears to be a valid answer. The current research, with the purpose of establishing the cycle capabilities of ASSB in practical applications, places emphasis on the development of a numerical ageing model based on the open-source coding language, Python. The model, combining a detailed diffusion mechanism with two significantly simplified temperature-dependent fitting parameters, is targeted at forecasting the development of the solid electrolyte interface (SEI), which is largely assessed as the major cause of battery capacity fading. Initially, the model is created and verified on a commercial LiFePO4 battery with a 98% regression index. Thenceforth, the model is tweaked on prototype solid-state batteries until a 99% fidelity is reached. Even if delivering an extended sequence of benefits, ASSB could suffer from low cyclability performance, substantially issued by the lack of contact between the electrodes and the solid-state electrolyte. Proceeding with the dissertation, the SEI growth for ASSBs implementing different anode materials is investigated as a function of temperature, concentration, and time. The enhanced ageing model is then validated over dynamic conditions, showing excellent residual capacity predictability. Therefore, it was possible to examine ASSBs at a cell level across the Class 3b Worldwide Harmonized Light vehicle Test Procedure (WLTP) test, revealing encouraging results in terms of durability. All the ASSB configurations under scrutiny were able to offer more than 76% capacity retention over 4184 WLTP cycles. Even if they still require elevated operating temperatures, the findings from the enhanced model offer substantial reasons to further explore solid-state batteries in order to apply them at a commercial level. Undoubtedly, this task would demand a lot of work to match the actual manufacturing level of lithium-ion batteries with liquid electrolyte, but it may lead to a solid and long-term transition towards electric mobility.