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Highlights: Recent advances in electrochemical energy storage based on nano- and micro-structured (NMS) scaffolds are summarized and discussed. The fundamentals, superiorities, and design principle of NMS scaffolds are outlined. Given the present progress, the ongoing challenges and promising perspectives are highlighted. Adopting a nano- and micro-structuring approach to fully unleashing the genuine potential of electrode active material benefits in-depth understandings and research progress toward higher energy density electrochemical energy storage devices at all technology readiness levels. Due to various challenging issues, especially limited stability, nano- and micro-structured (NMS) electrodes undergo fast electrochemical performance degradation. The emerging NMS scaffold design is a pivotal aspect of many electrodes as it endows them with both robustness and electrochemical performance enhancement, even though it only occupies complementary and facilitating components for the main mechanism. However, extensive efforts are urgently needed toward optimizing the stereoscopic geometrical design of NMS scaffolds to minimize the volume ratio and maximize their functionality to fulfill the ever-increasing dependency and desire for energy power source supplies. This review will aim at highlighting these NMS scaffold design strategies, summarizing their corresponding strengths and challenges, and thereby outlining the potential solutions to resolve these challenges, design principles, and key perspectives for future research in this field. Therefore, this review will be one of the earliest reviews from this viewpoint. [ABSTRACT FROM AUTHOR]

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Layered double hydroxides (LDHs), as a class of typical two‐dimensional materials, have sparked increasing interest in the field of energy storage and conversion. In the last few years, the research about LDHs as electrode active materials has seen much progress in terms of structure designing, material synthesis, properties tailoring, and applications. In this review, we focus on the integrated nanostructural electrodes (INEs) construction using LDH materials, including pristine LDH‐INEs, hybrid LDH‐INEs, and LDH derivative‐INEs, as well as the performance advantages and applications of LDH‐INEs. Moreover, in the final section, the insights about challenges and prospective in this promising research field were concluded, especially in regulation of intrinsic activity and uncovering of structure–activity relationship, which would push forward the development of this fast‐growing field. [ABSTRACT FROM AUTHOR]

As a promising large-scale energy storage device, the vanadium redox flow battery (VRFB) has attracted attention due to its excellent safety, the independence between energy capacity and power capacity, the suitable polarization potential, and the ability to avoid cross-contamination. In this work, a 3D model of VRFB is developed based on the open-source computational fluid dynamics (CFD) platform OpenFOAM, which is well-validated. Then, the effect of operating conditions is studied, which shows that a higher electrolyte concentration can reduce the overpotential and increase the discharge voltage. Reducing the current density can increase the deepness of charge and discharge, reduce the electrolyte concentration gradient, the mass transfer loss and the activation loss. In addition, the effect of electrode porosity is studied that the overpotential decreases near the membrane and increases near the current collector with increasing porosity. Finally, the effect of porosity changes in different directions is studied, and an attempt is made to utilize this overpotential distribution by introducing the gradient-porosity electrode to reduce the non-uniformity of overpotential. The gradient-porosity electrode design using higher porosity near the membrane and lower porosity near the current collector can effectively improve the distribution of overpotential and increase battery performance by 1.67 mV. [Display omitted] • A VRFB model is developed under open-source environment OpenFOAM. • The effect of electrolyte concentration and current density is studied. • The overpotential distribution pattern caused by different porosity is summarized. • The performance with the gradient-porosity electrode is increased by 1.67 mV. [ABSTRACT FROM AUTHOR]

Taking advantage of a high theoretical energy density of 2567 Wh kg -1 , lithium sulfur batteries (LSBs) have been considered promising candidates for next-generation energy storage systems. Nevertheless, challenging issues involving both sulfur cathode and lithium anode hinder their practical applications, which are followed by the extensive research efforts to resolve them. A wide variety of carbon nanomaterials with different characteristics has played an important role in enhancing the performance of LSBs via immobilizing sulfur in cathodes, accommodating the volume expansion of sulfur, enhancing the reaction kinetics and stabilizing lithium anodes. This report overviews the state-of-the-art progress in designing and fabricating nanocarbon for advanced LSBs with particular focuses on the correlations among porosity, electrical conductivity and surface chemistry as some of the most critical factors. More importantly, statistical analysis of electrochemical performance of batteries collected from literatures allows us to identify substantial disparities between the current achievements and the requirements for real-world applications. In an effort to bridge this gap, we highlight recent advances in the design of LSBs with improved sulfur loading, enhanced charge transfer and minimized electrolyte/sulfur ratio. Conclusions and perspectives for future development of nanocarbon in LSBs are proposed. [ABSTRACT FROM AUTHOR]

Lithium metal batteries have achieved large-scale application, but still have limitations such as poor safety performance and high cost, and limited lithium resources limit the production of lithium batteries. The construction of these devices is also hampered by limited lithium supplies. Therefore, it is particularly important to find alternative metals for lithium replacement. Sodium has the properties of rich in content, low cost and ability to provide high voltage, which makes it an ideal substitute for lithium. Sulfur-based materials have attributes of high energy density, high theoretical specific capacity and are easily oxidized. They may be used as cathodes matched with sodium anodes to form a sodium-sulfur battery. Traditional sodium-sulfur batteries are used at a temperature of about 300 °C. In order to solve problems associated with flammability, explosiveness and energy loss caused by high-temperature use conditions, most research is now focused on the development of room temperature sodium-sulfur batteries. Regardless of safety performance or energy storage performance, room temperature sodium-sulfur batteries have great potential as next-generation secondary batteries. This article summarizes the working principle and existing problems for room temperature sodium-sulfur battery, and summarizes the methods necessary to solve key scientific problems to improve the comprehensive energy storage performance of sodium-sulfur battery from four aspects: cathode, anode, electrolyte and separator. [ABSTRACT FROM AUTHOR]

The chemistry and electrochemistry basic fields have been active for the last two decades of the past century studying how the modification of the electrodes' surface by coating with conductive thin films enhances their electrocatalytic activity and sensitivity. In light of the development of alternative sustainable ways of energy storage and carbon dioxide conversion by electrochemical reduction, these research studies are starting to jump into the 21st century to more applied fields such as chemical engineering, energy and environmental science, and engineering. The huge amount of literature on experimental works dealing with the development of CO2 electroreduction processes addresses electrocatalyst development and reactor configurations. Membranes can help with understanding and controlling the mass transport limitations of current electrodes as well as leading to novel reactor designs. The present work makes use of a bibliometric analysis directed to the papers published in the 21st century on membrane-coated electrodes and electrocatalysts to enhance the electrochemical reactor performance and their potential in the urgent issue of carbon dioxide capture and utilization. [ABSTRACT FROM AUTHOR]

Developing effective energy storage systems is crucial for the successful implementation of solar energy. Recently, incorporating suitable photocatalysts into the electrodes to form photo-assisted non-aqueous lithium-oxygen batteries significantly decreases the overpotentials and improves energy efficiency, providing a striking way of utilizing solar light. Focusing on this design, this work provides a timely summary of the latest progress and the remaining challenges of photo-assisted non-aqueous lithium-oxygen batteries. The working mechanisms and battery configurations are first introduced. Then, the advances in the photocatalyst materials are detailedly summarized, and the influence of illumination on the electrolyte is also reviewed. Moreover, the optimization of the operating protocols for extending the cycle life is also discussed. Future research should focus on the photocatalyst explorations, battery structure design, and operating management. The insights obtained from these investigations also benefit the development of other energy storage systems for the wide application of solar energy. • This work provides a timely summary of photo-assisted non-aqueous Li–O 2 batteries. • The mechanisms, configurations, materials, and operating protocols are reviewed. • Material stability, structure design, and operating management worth attention. [ABSTRACT FROM AUTHOR]

The electrochemical performance of vanadium redox flow batteries (VRFBs) was enhanced via laser-patterned graphite felt (GF) electrodes. The laser-structured GF electrodes engineered via preparing a series of well-ordered microscopic channel structures with an average width of 200 μm, creating a three-dimensional carbon framework. The ultrafast laser patterning increased the porosity by 10%, as compared to pristine electrode. The analysis of the overpotential distribution using electrochemical impedance spectroscopy revealed that the electrode polarization involving charge transfer and diffusion resistance is strongly alleviated with the aid of carbon micro-perforation. The advanced design of laser-structured GF electrode also exhibits high rate capability, low internal resistance, and excellent cyclability. The improved performance was attributed to the synergistic effect involving (i) high electrochemically active surface area for rapid electrochemical reactions (i.e., V(II)/V(III) and V(IV)/V(V) redox couples) and (ii) excellent transport properties for facile electron/ion/species transport. The micro-scale channels created with the laser-ablation technique act as capillary structures and enabled homogeneous and rapid wetting of GF electrodes as formulated with the classical Washburn equation. The VRFB equipped with the laser-structured GF electrodes delivered a high discharge capacity with exceptional capacity retention upon extended cycling (>84.9%). Accordingly, the design of laser-structured electrode paves the pathway towards finely tuning the electrode internal microstructure for improved cyclability, durability, and capacity retention in various electrochemical energy storage/conversion devices (e.g. all-vanadium redox flow batteries). Image 1 • Vanadium redox flow battery was assembled by laser-patterned graphite felt. • The laser patterning increased the porosity by 10%, as compared to pristine one. • The electrode polarization is strongly alleviated due to carbon micro-perforation. • High rate capability, low resistance, and excellent cyclability are achievable. • The enhancement was attributed to high surface area improved transport properties. [ABSTRACT FROM AUTHOR]