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Background and Objectives: Rechargeable zinc-air batteries present a compelling alternative to lithium-ion batteries due to their safety features, affordability, and high theoretical energy density, primarily attributed to non-flammable electrolytes. However, the practical performance of zinc-air batteries is limited by slow air cathode reaction kinetics. This research aims to evaluate the performance of monolithic carbon electrodes derived from spruce wood as air cathodes in zinc-air batteries. Materials and Methods: Air-dried sapwood of spruce (Picea orientalis) was utilized as the starting material for fabricating carbon electrodes. The wood pieces were initially cut into cross-sectional, radial, and tangential blocks with dimensions of 3 × 50 × 50 mm. Monolithic carbon electrodes were then produced by subjecting the wood blocks to slow pyrolysis under an inert atmosphere at specific temperature programs. All pyrolyzed samples were sanded to a thickness of approximately 1 mm. The study investigated and analyzed the effect of the maximum pyrolysis temperature (800 and 1000 °C) and the type of wood cutting on the morphological and physicochemical properties of the carbon electrodes, as well as their electrochemical performance in zinc-air batteries. Results: The results demonstrated a significant influence of the maximum pyrolysis temperature and the type of wood cutting, relative to the fiber direction, on the electrochemical performance of the fabricated carbon electrodes used as air cathodes. Increasing the maximum pyrolysis temperature from 800 to 1000 °C led to an improvement in the electrochemical performance of the carbon electrodes. Furthermore, monolithic carbon electrodes derived from spruce wood with large crosssectional surface areas exhibited superior electrochemical characteristics compared to their counterparts with large tangential and radial surface areas. Overall, zinc-air batteries assembled with carbon cathode electrodes of large cross-sectional area, fabricated at a pyrolysis temperature of 1000 °C, demonstrated significantly enhanced electrochemical performance in impedance spectroscopy and linear sweep voltammetry tests. Conclusion: In summary, the improved electrochemical performance of the air cathodes with an increased maximum pyrolysis temperature was attributed to the development of structural porosity and specific surface area in the fabricated electrodes. For spruce wood-derived electrodes, the presence of longitudinally oriented tracheids, along with the smaller thickness of the monolithic carbon electrodes compared to tracheid length, likely facilitated efficient electrolyte and electron transport within the cathode electrodes' large cross-sectional area. This efficient transport mechanism is believed to contribute to the overall improved electrochemical performance of the cell. [ABSTRACT FROM AUTHOR]

This article presents a new energy management strategy (EMS) for optimal power allocation in the battery/supercapacitor hybrid energy storage (HESS) in DC microgrid applications. The proposed system is composed of a semiactive structure where the supercapacitor is directly connected to DC bus. In this structure, since the main purpose of the HESS is to maintain the DC bus voltage at the desired value, controlling the supercapacitor becomes more important. While, in the semi-active structure, there is no control on the supercapacitor. In this paper, by considering the supercapacitor current as a cost function in the optimization problem, this challenge has been solved. Also, in the case of microgrid excess power mode, a new cost function has been considered to charge the battery with a constant current to reduce the charging time and improve its lifespan. Another objective is to increase battery life by responding the supercapacitor to the sudden power changes and drawing a smooth current from the battery. In order to online determination of the optimal global solution, this multi-objective problem has been converted into a single-objective problem by use of the weighted method and then solved using KKT conditions. Therefore, real-time implementation is the main advantage of the proposed method. Finally, using simulation, the performance of the proposed method is compared with an adaptive cutoff frequency filter-based method and fuzzy logic method, in three 24 seconds different scenarios, in terms of the DC bus voltage regulation, the battery peak current, and the battery state of charge (SoC).

The global problem of air pollution and its consequences, as well as the reduction of fossil fuel reserves, have created the need to use alternative energy sources. Therefore, it is necessary to create and develop the required infrastructure of renewable resources in the production of clean energy. In addition, the use of renewable energy sources is essential at all times to replace non-renewable sources continuously The storage of renewable energy, especially on a large scale, is the requirement of this goal. Batteries are one of the most potential technologies for this purpose Currently, lithium ion and flow batteries are the focus of studies for development and commercialization compared to other types of batteries. Flow batteries, especially vanadium type, are more capable of improving components and commercialization for large scale due to the availability of vanadium elements in nature, elimination of the ignition, and cost reduction compared to lithium batteries. One of the main challenges in this type of battery is the development of a high-performance membrane with low cost. Therefore, the description of performance and components of this type of battery, including the role of polymer membrane and characteristics, can create a perspective for its development and commercialization. To this end, in the present paper, the overall structure, performance, and constituent components of this type of battery have been introduced, focusing on the role of polymer membrane and its characteristics as the key component of its technology. Additionally, in each section recent results reported by the researchers have been presented in brief. Finally according to the literature survey, the future perspective, and remaining challenges for the development of this technology are mentioned.