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With the rapid development of renewable energy harvesting technologies, there is a significant demand for long-duration energy storage technologies that can be deployed at grid scale. In this regard, polysulfide-air redox flow batteries demonstrated great potential. However, the crossover of polysulfide is one significant challenge. Here, we report a stable and cost-effective alkaline-based hybrid polysulfide-air redox flow battery where a dual-membrane-structured flow cell design mitigates the sulfur crossover issue. Moreover, combining manganese/carbon catalysed air electrodes with sulfidised Ni foam polysulfide electrodes, the redox flow battery achieves a maximum power density of 5.8 mW cm−2 at 50% state of charge and 55 °C. An average round-trip energy efficiency of 40% is also achieved over 80 cycles at 1 mA cm−2. Based on the performance reported, techno-economic analyses suggested that energy and power costs of about 2.5 US$/kWh and 1600 US$/kW, respectively, has be achieved for this type of alkaline polysulfide-air redox flow battery, with significant scope for further reduction.

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Experiments and numerical results are presented to demonstrate the adverse effects of a zone melting method in (Bi2Te3)0.25(Sb2Te3)0.75 thermoelectric crystallization, on mass transport. The zone melting method shows a considerable effect from the deflection of the solid–liquid interface, and the Bi2Te3 stoichiometry changes significantly. Electrical conductivity measurements of the crystallized ingot were carried out at stepped intervals of length (each step is 7 mm). A considerable gradient was observed in the readings from the tip to the end of the ingot. To understand this variation taking into account all empirical aspects of crystal growth, we conducted a numerical study because it gives vast information on the crystal growth process. Simulating the crystallization process and characterization of the ingot reveals a variation in the measured values of the thermoelectric parameters, which was attributed to the deviation of Bi2Te3 concentration along the ingot.

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