Conceptual Design of Solid-State Li-Battery for Urban Air Mobility

The negative impact of internal combustion engines on the environment is a major concern in metropolitan areas due to the continued rapid growth and high overall level in the number of vehicles, population, and traffic congestion. Electric vertical take-off and landing (eVTOL) aircraft promises a new era for urban regional transportation and air mobility to address the challenges mentioned above. Nonetheless, providing electrical energy storage systems, like batteries, is one of the key issues with such aircraft. Here, the non-flammable technology of all-solid-state Li batteries with high theoretical gravimetric energy is an attractive option. Modelling allows for a knowledge-driven assessment of the potential of this technology. We here used a combination of a pseudo-2-dimensional cell model with a microstructure surrogate model approach to acquire a better understanding of the effect of the cathode microstructure on the internal process limitations. This model is incorporated into a global optimisation algorithm to predict optimum battery size with respect to the dynamic load demand of eVTOL. When carbon black and active materials are premixed, the battery performs better than when solid electrolyte and active materials are premixed, particularly for low amounts of carbon black in the cathode combination, i.e., 5%. Further, results indicate that future electrification of transportation powertrains would necessitate optimising the composition and distribution of electrode components to fulfil the high demands for power and energy density. By enhancing transport through the microstructure and improving the material\u27s intrinsic conductivity, it is possible to significantly increase the effective diffusivity and conductivity of ASSB, and hence the mission range

Unveiling the interaction of reactions and phase transition during thermal abuse of Li-ion batteries

Safety considerations have always accompanied the development of new battery chemistries; this holds especially for the Li-ion battery with its highly reactive components. An overall assessment and decrease of risks of catastrophic failures such as during thermal runaway, requires an in-depth and quantitative understanding of the ongoing processes and their interaction. This can be provided by predictive mathematical models. Thus, we developed a thermal runaway model that focuses on rigorous modelling of thermodynamic properties and reactions of each component within a Li-ion battery. Moreover, the presented model considers vapour–liquid equilibria of a binary solvent mixture for the first time. Simulations show a fragile equilibrium between endothermic and exothermic reactions, such as LiPF$_{6}$ and LEDC decomposition, in the early phases of self-heating. Further, an autocatalytic cycle involving the production of HF and the SEI component Li$_{2}$CO$_{3}$ could be revealed. Additionally, the unpredictability of the thermal runaway could be directly correlated to availability of LEDC or contaminants such as water. Also, solvent boiling can have a significant influence on the self-heating phase of a Li-ion battery, due to its endothermic nature. Further analysis revealed that the rising pressure, stemming from gassing reactions, can suppress solvent boiling until the thermal runaway occurs

Strategies towards enabling lithium metal in batteries: Interphases and electrodes

Despite the continuous increase in capacity, lithium-ion intercalation batteries are approaching their performance limits. As a result, research is intensifying on next-generation battery technologies. The use of a lithium metal anode promises the highest theoretical energy density and enables use of lithium-free or novel high-energy cathodes. However, the lithium metal anode suffers from poor morphological stability and Coulombic efficiency during cycling, especially in liquid electrolytes. In contrast to solid electrolytes, liquid electrolytes have the advantage of high ionic conductivity and good wetting of the anode, despite the lithium metal volume change during cycling. Rapid capacity fade due to inhomogeneous deposition and dissolution of lithium is the main hindrance to the successful utilization of the lithium metal anode in combination with liquid electrolytes. In this perspective, we discuss how experimental and theoretical insights can provide possible pathways for reversible cycling of two-dimensional lithium metal. Therefore, we discuss improvements in the understanding of lithium metal nucleation, deposition, and stripping on the nanoscale. As the solid-electrolyte interphase (SEI) plays a key role in the lithium morphology, we discuss how the proper SEI design might allow stable cycling. We highlight recent advances in conventional and (localized) highly concentrated electrolytes in view of their respective SEIs. We also discuss artificial interphases and three-dimensional host frameworks, which show prospects of mitigating morphological instabilities and suppressing large shape change on the electrode level