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

Efficient photocatalysis through conductive polymer coated FTO counter electrode in platinum free dye sensitized solar cells

This is the final version. Available on open access from Elsevier via the DOI in this recordPlatinum-free counter electrodes are crucial for developing cost effective solar energy harvesting technology. We describe here the fabrication of efficient platinum free FTO counter electrodes for dye sensitized solar cells based on pristine polyaniline, polyaniline doped with sulfuric acid, ammonuim lauryl sulfate, as well as binary doped with sulfuric acid and ammonium lauryl sulphate. The characteristics of these counter electrodes were analyzed using cyclic voltammetry, photocurrent density–voltage and electrochemical impedance spectroscopy measurements. At optimized fabrication conditions, the counter electrode shows significantly high photoelectric conversion efficiency of 4.54% compared to 4.03% for reference platinum counter electrode. Charge transfer resistance at the interface between electrolyte and counter-electrode is also decreased for the optimized polyaniline based counter electrode. Furthermore, the device presented characteristics of multiple start/stop ability and fast activity. The simple preparation procedure, low cost and improved photoelectric properties permit fabricated counter electrode to be a reliable alternative for dye sensitized solar cells.Engineering and Physical Sciences Research Council (EPSRC)Alexander von Humboldt Foundation, GermanyHigher Education Commission Pakista

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

3d polyaniline nanofibers anchored on carbon paper for high-performance and light-weight supercapacitors

In the field of advanced energy storage, nanostructured Polyaniline (PANI) based materials hold a special place. Extensive studies have been done on the application of PANI in supercapacitors, however, the structure–property relationship of these materials is still not understood. This paper presents a detailed characterization of the novel sodium phytate doped 3D PANI nanofibers anchored on different types of carbon paper for application in supercapacitors. An excellent relationship between the structures and properties of the synthesized samples was found. Remarkable energy storage characteristics with low values of solution, charge transfer and polarization resistance and a specific capacitance of 1106.9 ± 1.5 F g$^{−1}$ and 779 ± 2.6 F g$^{−1}$ at current density 0.5 and 10 Ag$^{−1}$, respectively, was achieved at optimized conditions. The symmetric supercapacitor assembly showed significant enhancement in both energy density and power density. It delivered an energy density of 95 Wh kg$^{−1}$ at a power of 846 W kg$^{−1}$. At a high-power density of 16.9 kW kg$^{−1}$, the energy density can still be kept at 13 Wh kg$^{−1}$. Cyclic stability was also checked for 1000 cycles at a current density of 10 Ag$^{−1}$ having excellent retention, i.e., 96%