Room-temperature sodium-ion batteries (SIBs) are regarded as promising candidates for smart grids and large-scale energy storage systems (EESs) due to their significant benefits of abundant and ...low-cost sodium resource. Among the previously reported cathode materials for SIBs, layered transition-metal oxides and polyanion-type materials are considered to be the most attractive options. Although many layered transition-metal oxides can provide high capacity due to their small molecular weight, their further application is hindered by low output voltage (mostly lower than 3.5 V), irreversible phase transition as well as storage instability. Comparatively, polyanion-type materials exhibit higher operating potentials due to the inductive effect of polyanion groups. Their robust 3D framework significantly decreases the structural variations during sodium ion de/intercalation. Moreover, the effect of strong X-O (X = S, P, Si,
etc.
) covalent bonds can effectively inhibit oxygen evolution. These advantages contribute to the superior cycle stability and high safety of polyanion-type materials. However, low electronic conductivity and limited capacity still restrict their further application. This review summarizes the recent progress of polyanion-type materials for SIBs, which include phosphates, fluorophosphates, pyrophosphates, mixed phosphates, sulfates, and silicates. We also discuss the remaining challenges and corresponding strategies for polyanion-type materials. We hope this review can provide some insights into the development of polyanionic materials.
This review summarizes the recent progress and remaining challenges of polyanion-type cathodes, providing guidelines towards high-performance cathodes for sodium ion batteries.
The oxygen reduction reaction (ORR) is one of the most important reactions in life processes and energy conversion systems. To alleviate global warming and the energy crisis, the development of ...high‐performance electrocatalysts for the ORR for application in energy conversion and storage devices such as metal–air batteries and fuel cells is highly desirable. Inspired by the biological oxygen activation/reduction process associated with heme‐ and multicopper‐containing metalloenzymes, iron and copper‐based transition‐metal complexes have been extensively explored as ORR electrocatalysts. Herein, an outline into recent progress on non‐precious‐metal electrocatalysts for the ORR is provided; these electrocatalysts do not require pyrolysis treatment, which is regarded as desirable from the viewpoint of bioinspired molecular catalyst design, focusing on iron/cobalt macrocycles (porphyrins, phthalocyanines, and corroles) and copper complexes in which the ORR activity is tuned by ligand variation/substitution, the method of catalyst immobilization, and the underlying supporting materials. Current challenges and exciting imminent developments in bioinspired ORR electrocatalysts are summarized and proposed.
An outline of recent progress on non‐precious‐metal electrocatalysts for the oxygen reduction reaction (ORR) is presented from the viewpoint of bioinspired molecular catalyst design, with a focus on iron/cobalt macrocycles and copper complexes in which the ORR activity is tuned by ligand modification, the method of catalyst immobilization, and the underlying supporting materials (see scheme).
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This paper introduces series work of common-mode (CM) voltage reduction for the paralleled inverters. The paralleled inverters' phase-legs are connected through coupling inductors and the combined ...three-phase currents are provided to the load. Interleaving is an approach to reduce the CM voltage for the paralleled inverters but it cannot eliminate CM voltage. A novel pulse-width-modulation (PWM) method for paralleled inverters which can theoretically achieve zero CM voltage is developed. Considering the basic voltage vectors in each inverter, novel paralleled voltage vectors which have zero CM voltage are proposed to combine the reference voltage vector. The action time's distribution and voltage vectors' sending sequence for each inverter are also introduced. The proposed PWM method can make sure the voltage of the two inverters are balanced in each switching cycle and limits the circulating current through small coupling inductors. Similar to interleaving space vector PWM, the proposed zero CM PWM also has the ability to reduce the output current ripple and electromagnetic interference (EMI). Simulation and experimental results are provided to show the advantage of paralleled inverters in CM voltage reduction and validate the proposed method has good performance to reduce CM current and CM EMI noise.
Parallel control and management have been proposed as a new mechanism for conducting operations of complex systems, especially those that involved complexity issues of both engineering and social ...dimensions, such as transportation systems. This paper presents an overview of the background, concepts, basic methods, major issues, and current applications of Parallel transportation Management Systems (PtMS). In essence, parallel control and management is a data-driven approach for modeling, analysis, and decision-making that considers both the engineering and social complexity in its processes. The developments and applications described here clearly indicate that PtMS is effective for use in networked complex traffic systems and is closely related to emerging technologies in cloud computing, social computing, and cyberphysical-social systems. A description of PtMS system architectures, processes, and components, including OTSt, Dyna CAS, aDAPTS, iTOP, and TransWorld is presented and discussed. Finally, the experiments and examples of real-world applications are illustrated and analyzed.
Compared with the widely used constant switching frequency pulse-width-modulation (PWM) method, variable switching frequency PWM can benefit more because of the extra freedom. Based on the analytical ...expression of current ripple of three-phase converters, variable switching frequency control methods are proposed to satisfy different ripple requirements. Switching cycle T_{s} is updated in DSP in every interruption period based on the ripple requirement. Two methods are discussed in this paper. The first method is designed to arrange the current ripple peak value within a certain value and can reduce the equivalent switching frequency and electromagnetic interference (EMI) noise; the second method is designed to keep ripple current RMS value constant and reduce the EMI noise. Simulation and experimental results show that variable switching frequency control could improve the performance of EMI and efficiency without impairing the power quality.
Rechargeable magnesium and calcium metal batteries (RMBs and RCBs) are promising alternatives to lithium-ion batteries because of the high crustal abundance and capacity of magnesium and calcium. ...Yet, they are plagued by sluggish kinetics and parasitic reactions. We found a family of methoxyethyl-amine chelants that greatly promote interfacial charge transfer kinetics and suppress side reactions on both the cathode and metal anode through solvation sheath reorganization, thus enabling stable and highly reversible cycling of the RMB and RCB full cells with energy densities of 412 and 471 watt-hours per kilogram, respectively. This work provides a versatile electrolyte design strategy for divalent metal batteries.
The hierarchical aggregation of molecular nanostructures from multiple components is a grand synthetic challenge, which requires highly selective linkage control. We demonstrate how two orthogonal ...linkage groups, that is, organotin and lanthanide cations, can be used to drive the aggregation of a giant molecular metal oxide superstructure. The title compound {(Sn(CH3)2)2O4{CeW5O18 TeW4O16CeSn(CH3)24TeW8O314}2}46− (1 a) features dimensions of ca. 2.2×2.3×3.4 nm3 and a molecular weight of ca. 25 kDa. Structural analysis shows the hierarchical aggregation from several independent subunits. Initial biomedical tests show that 1 features an inhibitory effect on the proliferation of HeLa cells based on an apoptosis pathway. In vivo experiments in mice reveal the antiproliferative activity of 1 and open new paths for further development of this new compound class.
Hierarchical assembly of a giant heterometallic polyoxotungstate supercluster with a molecular weight of ca. 25 kDa is reported. Geometrically unrestricted cerium(III) and geometrically restricted dimethyl tin cation linkers are used to gain access to a giant molecular species featuring three different polyoxometalate building units. The compound demonstrates in vitro and in vivo antiproliferative activity against HeLa cervical cancer cell lines.
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The increasing demand for replacing conventional fossil fuels with clean energy or economical and sustainable energy storage drives better battery research today. Sodium‐ion batteries (SIBs) are ...considered as a promising alternative for grid‐scale storage applications due to their similar “rocking‐chair” sodium storage mechanism to lithium‐ion batteries, the natural abundance, and the low cost of Na resources. Searching for appropriate electrode materials with acceptable electrochemical performance is the key point for development of SIBs. Layered transition metal oxides represent one of the most fascinating electrode materials owing to their superior specific capacity, environmental benignity, and facile synthesis. However, three major challenges (irreversible phase transition, storage instability, and insufficient battery performance) are known for cathodes in SIBs. Herein, a comprehensive review on the latest advances and progresses in the exploration of layered oxides for SIBs is presented, and a detailed and deep understanding of the relationship of phase transition, air stability, and electrochemical performance in layered oxide cathodes is provided in terms of refining the structure–function–property relationship to design improved battery materials. Layered oxides will be a competitive and attractive choice as cathodes for SIBs in next‐generation energy storage devices.
The recent progress in layered oxide cathodes for sodium‐ion batteries is comprehensively reviewed. Some new perspectives concentrating on phase transition, air stability, and electrochemical performance in layered cathodes are provided, in terms of refining the structure–function–property relationship to rationally design better electrode materials.
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Single‐crystalline cathode materials have attracted intensive interest in offering greater capacity retention than their polycrystalline counterparts by reducing material surfaces and phase ...boundaries. However, the single‐crystalline LiCoO2 suffers severe structural instability and capacity fading when charged to high voltages (4.6 V) due to Co element dissolution and O loss, crack formation, and subsequent electrolyte penetration. Herein, by forming a robust cathode electrolyte interphase (CEI) in an all‐fluorinated electrolyte, reversible planar gliding along the (003) plane in a single‐crystalline LiCoO2 cathode is protected due to the prevention of element dissolution and electrolyte penetration. The robust CEI effectively controls the performance fading issue of the single‐crystalline cathode at a high operating voltage of 4.6 V, providing new insights for improved electrolyte design of high‐energy‐density battery cathode materials.
Single‐crystalline cathode materials have attracted intensive interest. However, the single‐crystalline LiCoO2 suffers severe structural instability and capacity fading when charged to high voltages (4.6 V vs Li/Li+) due to Co and O element dissolution, crack formation, and electrolyte penetration. In this work, the above problems are inhibited by forming a robust cathode electrolyte interphase (CEI) on the surface of LiCoO2.
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In order to solve the problem that most of the existing mine-used smart phones only have the functions of voice calls, video photos, data transmission and so on, and do not have the functions of ...precise positioning, position coordinate display, message linkage, an identification card based on UWB technology is designed. The identification card realizes two-way data communication with the smart phone through low-power bluetooth. The identification card completes the precise positioning with the UWB station using the TOF positioning algorithm, obtains the position coordinate information, sends it to the smart phone through the low-power bluetooth (BLE), and displays the current specific position coordinates through the mine GIS roadway map on the smart phone APP. This paper introduces the key technologies of the identification card in detail, including mine roadway position coordinate model, precise positioning algorithm, message linkage reliable transmission mechanism, low power consumption sleep technology. T
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