Fe3O4/carbon nanofibres with necklace architecture for enhanced electrochemical energy storage

Fe3O4 spherulites on carbon nanofibres (CNFs) to form novel necklace structures have been synthesised using a facile and scalable hydrothermal method, and their morphology and structure have been characterized using a range of electron microscopy and other techniques. The formation mechanism for the necklace structure has been proposed. The Fe3O4/CNF necklaces were sprayed onto large area current collectors to form electrodes with no binder and then investigated for their potential in supercapacitor and Li-ion battery applications. Supercapacitor electrodes in an aqueous KOH electrolyte delivered a high capacitance of 225 F g-1 at 1 A g-1 and Li-ion battery electrodes delivered a reversible capacity of over 900 mA h g-1 at 0.05 C, and there was good cycling stability and rate capability in both configurations. When compared with the reduced performance of mixtures of the same materials without the necklace morphology, the enhanced performance can be ascribed to the robust, high mechanical stability and open scaffold structure in the necklace electrode that provides high ion mobility, while the percolating CNFs ensure low resistance electrical connection pathways to every electroactive Fe3O4 spherulite to maximize storage behavior

Dimensional Upgrade Induced Enriched Active Sites and Intensified Intramolecular Electron Donor–Acceptor Interaction to Boost Oxygen Reduction Electrocatalysis

Conjugated 2D covalent organic frameworks (2D‐COFs) have garnered interest as potential cost‐efficient noble‐metal‐free electrocatalysts, owing to their structural flexibility, well‐defined molecular architecture, high compatibility, and environmental sustainability. However, their suboptimal activity, primarily attributed to their low active site utilization and limited electron transfer ability, considerably impedes their implementation in real‐world electrocatalytic systems. Herein, the molecular dimensionality of a 2D‐COF containing tris‐triazine ring (2D‐Tr‐COF) is upgraded to generate its 3D counterpart (3D‐Tr‐COF), enabling a direct comparison between 2D‐ and 3D‐ COFs. These findings reveal that slightly altering the spatial structure in plane (from 2D to 3D) by substituting amine building blocks leads to significant variations in molecular architecture and performance for oxygen reduction reaction. The results indicate that 3D‐Tr‐COF with enlarged lattice spacing, more active species, and reduced conjugated degree, possesses enriched active sites. Moreover, the intensified intramolecular electron donor–acceptor interaction between the tris‐triazine ring and its neighboring imino linkage of 3D‐Tr‐COF optimizes the electronic/band structure and facilitates the charge transfer, resulting in enhanced intrinsic activity compared to 2D‐Tr‐COF. The extensively optimized 3D‐Tr‐COF demonstrates a half‐wave potential of 0.833 V, on par with the state‐of‐the‐art Pt/C. These findings offer valuable insights into dimension modulation strategies for COF‐based electrocatalyst designing

High‐Entropy Oxides for Rechargeable Batteries

High‐entropy oxides (HEOs) have garnered significant attention within the realm of rechargeable batteries owing to their distinctive advantages, which encompass diverse structural attributes, customizable compositions, entropy‐driven stabilization effects, and remarkable superionic conductivity. Despite the brilliance of HEOs in energy conversion and storage applications, there is still lacking a comprehensive review for both entry‐level and experienced researchers, which succinctly encapsulates the present status and the challenges inherent to HEOs, spanning structural features, intrinsic properties, prevalent synthetic methodologies, and diversified applications in rechargeable batteries. Within this review, the endeavor is to distill the structural characteristics, ionic conductivity, and entropy stabilization effects, explore the practical applications of HEOs in the realm of rechargeable batteries (lithium‐ion, sodium‐ion, and lithium‐sulfur batteries), including anode and cathode materials, electrolytes, and electrocatalysts. The review seeks to furnish an overview of the evolving landscape of HEOs‐based cell component materials, shedding light on the progress made and the hurdles encountered, as well as serving as the guidance for HEOs compositions design and optimization strategy to enhance the reversible structural stability, electrical properties, and electrochemical performance of rechargeable batteries in the realm of energy storage and conversion

Rational Design of Organic Electrocatalysts for Hydrogen and Oxygen Electrocatalytic Applications

Efficient electrocatalysts are pivotal for advancing green energy conversion technologies. Organic electrocatalysts, as cost-effective alternatives to noble-metal benchmarks, have garnered attention. However, the understanding of the relationships between their properties and electrocatalytic activities remains ambiguous. Plenty of research articles regarding low-cost organic electrocatalysts started to gain momentum in 2010 and have been flourishing recently though, a review article for both entry-level and experienced researchers in this field is still lacking. This review underscores the urgent need to elucidate the structure–activity relationship and design suitable electrode structures, leveraging the unique features of organic electrocatalysts like controllability and compatibility for real-world applications. Organic electrocatalysts are classified into four groups: small molecules, oligomers, polymers, and frameworks, with specific structural and physicochemical properties serving as activity indicators. To unlock the full potential of organic electrocatalysts, five strategies are discussed: integrated structures, surface property modulation, membrane technologies, electrolyte affinity regulation, and addition of anticorrosion species, all aimed at enhancing charge efficiency, mass transfer, and long-term stability during electrocatalytic reactions. The review offers a comprehensive overview of the current state of organic electrocatalysts and their practical applications, bridging the understanding gap and paving the way for future developments of more efficient green energy conversion technologies

Ultra-thin Fe₃C nanosheets promote the adsorption and conversion of polysulfides in lithium-sulfur batteries

Rational design of hierarchical porous materials with comprehensive properties, e.g. good conductivity, fine dispersibility for sulfur, strong adsorption and catalytic abilities to polysulfides (LiPSs), is urgently needed for the practical application of lithium-sulfur batteries (Li-S batteries). Here, based on density functional theory (DFT) computational results and the design concept of efficient, low-cost and environmental friendliness, we report an ultra-thin (~ 1 nm) Fe3C nanosheets growing on mesoporous carbon (Fe3C-MC) with large specific surface area of 686.9 m2 g-1 and pore volume of 6.52 cm3 g-1. Meanwhile, the formation mechanism of two-dimensional Fe3C is revealed according to DFT results. In the Fe3C-MC composite, the mesoporous carbon constructs a conductive network for dispersion of sulfur species, while Fe3C nanosheets play a key role in electronic transmission, LiPSs adsorption and conversion in Li-S batteries. As a result, the Fe3C-MC composite delivers a high initial capacity of 1530 mA h g-1 at 0.1 C, and a capacity of 699 mA h g-1 after 100 cycles at 0.5 C at a super-high sulfur loading of 9.0 mg cm-2, meaning a specific area capacity of 6.291 mA h cm-2. Such sulfur host is expected to accelerate the practical applications of Li-S batteries benefiting from the low-cost and large-scale process

UK research needs in grid scale energy storage technologies

This white paper provides a concise guide to key technology options for grid scale energy storage, with the aim of informing stakeholders in industry, government and the funding agencies of the opportunities and need for underpinning research into both current and emerging technologies for grid scale storage applications. The paper has been produced in recognition of both the need for cost effective, durable and safe grid scale energy storage solutions (across a wide range of power and energy levels) to support future low carbon energy systems and the need for underpinning research into new ideas and concepts to support the development and subsequent deployment of both emerging and new energy storage options

The 2021 battery technology roadmap

Sun, wind and tides have huge potential in providing us electricity in an environmental-friendly way. However, its intermittency and non-dispatchability are major reasons preventing full-scale adoption of renewable energy generation. Energy storage will enable this adoption by enabling a constant and high-quality electricity supply from these systems. But which storage technology should be considered is one of important issues. Nowadays, great effort has been focused on various kinds of batteries to store energy, lithium-related batteries, sodium-related batteries, zinc-related batteries, aluminum-related batteries and so on. Some cathodes can be used for these batteries, such as sulfur, oxygen, layered compounds. In addition, the construction of these batteries can be changed into flexible, flow or solid-state types. There are many challenges in electrode materials, electrolytes and construction of these batteries and research related to the battery systems for energy storage is extremely active. With the myriad of technologies and their associated technological challenges, we were motivated to assemble this 2020 battery technology roadmap

Toward low cost grid scale energy storage: supercapacitors based on up-cycled industrial mill scale waste

The data was created in word and excell files by Chaopeng in 2014. Mill scale is a waste product from the steel industry available cheaply in tonne quantities and consisting of various iron oxides. The supercapacitive behaviour of mill scale directly from the steel plant, and after various cheap and scalable physical and chemical treatments, has been studied in electrodes formed by spraying mill-scale containing suspensions onto large area current collectors. Half-cell and full cell supercapacitors in cheap, non-toxic aqueous sodium sulphite electrolyte were investigated by cyclic voltammetry, charge-discharge and electrochemical impedance spectroscopy, and delivered a capacitance of up to 92 F g-1 at a scan rate of 5 mV s-1, which was maintained at more than 80% after 5,000 cycles. The approximate costs of commercial and mill scale-based supercapacitors were compared, and showed that while mill scale absolute capacitances were lower than more expensive laboratory synthesised metal oxides, the cost per kilo-watt performance was competitive, especially for very large grid scale storage applications

Production of hollow and porous Fe2O3 from industrial mill scale and its potential for large-scale electrochemical energy storage applications

The data containing SEM images, XRD, XPS and electrochemical measurements was created in 2015. Mill scale, which is a waste product from the steel industry, abundantly available and comprising a mixture of iron oxides has been converted into hollow and porous Fe2O3 micro-rods using a faclie and scalable chemical treatment. The Fe2O3 morphology and structure was characterized by a range of electron microscopy and other techniques, and then sprayed into large area electrodes that were investigated for electrochemical supercapacitor and lithium ion battery applications. The Fe2O3 supercapacitor electrode delivered a specific capacitance of 346 F g-1 at 2 mV s-1 with 88% capacitance retention after 5,000 cycles, while the battery electrode delivered an initial reversible specific capacity of 953 mAh g-1 at 0.1 C, reducing to 933 mAh g-1 after 100 cycles and to 673 mAh g-1 at 5 C. The Fe2O3 electrodes had similar or superior performance to more costly, small batches of laboratory synthesised Fe2O3 in both supercapacitor and battery applications, which was ascribed to the hollow and porous structure that facilitated ion mobility throughout the electrodes, a high surface area and excellent strain accommodation during lithiation and de-lithiaiton