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The demand for newer, lighter, and smaller batteries with longer lifespans, higher energy densities, and generally improved overall battery performance has gone up along with the need for electric vehicles. Alternatives must be found because lithium sources are limited and the metal is expensive. Aligned with this, efforts are being carried out to enhance the battery performance of electric vehicles and have shown promise in allaying consumer concerns about range anxiety and safety. This demonstrates that the electric car market will remain very dynamic in the coming decades, with costs continuing to fall. However, developing advanced energy storage technologies from more abundant resources that are cheaper and safer than lithium-ion batteries is a viable option for future mobility and product sustainability. This paper recapitulates the current state of multivalent particularly zinc and iron metal-air battery applications for electric mobility. The cycle capability, range, costs, service life, safety, discharge, and charging rate are all investigated. Factors hampering the further development and marketing of these technologies in connection with possible solutions are also conferred.

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In this paper, we present a new model and design of a MEMS Stirling machine. The concept could be used to provide electricity to low level power systems. A modified adiabatic model including losses of a Stirling engine such as regenerator thermal efficiency, wall conduction, pressure drop, hysteresis, membrane finite speed and squeeze film damping losses is presented. A base design machine is proposed. A parametric study is conducted and used to derive guidelines for miniature design. Compared to macro-scale design, the same trend was observed for the influence of the thermal performance regenerator. However, different trends from macroscopic engines were observed: conduction losses are of major importance due to the low power of the miniature engines, hysteresis losses in the bounce space are also of high amplitude due to the small size if this volume, the choice of the working gas leads to hydrogen or air and not helium. We computed that membrane finite speed losses and squeeze film damping losses can be neglected in the investigated machine size. The first part of the paper presents the micromachine specific features, the second part describes the model, the last part presents the base design results and design guidelines.

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