Cobalt-based electrode materials for sodium-ion batteries

The demand for grid-scale energy storage systems has rapidly grown over recent years, to meet the requirements of structural innovation within the energy industry. Due to their inexpensive manufacturing and operating costs, and the similar electrochemical mechanism with the well-established lithium-ion batteries (LIBs), sodium ion batteries (SIBs) have been considered as an attractive candidate for grid-scale energy storage systems. A variety of cobalt-based cathode and anode materials, including cobalt oxides, cobalt chalcogenides and layered sodium cobaltates, have been synthesized and evaluated for sodium storage within the academic literature. In this article, we present a comprehensive review of the recent progress with cobalt-based electrodes (both as an anode and cathode material) used in SIBs. In detail, the electrochemical mechanisms, advantages and disadvantages, the relationship between crystalline structure and electrochemical performance and strategies to enhance the overall electrochemical performance of cobalt-based cathode and anode materials are discussed. Up to now, some cathode materials have already reached a high energy density, which is comparable to commercial LIBs. Furthermore, some cobalt-based materials can maintain a high Coulombic efficiency of over 99% with high reversible capacity during long cycling life. These encouraging results, allow such cobalt-based electrode materials to be a potential solution for grid-scale SIB systems

Promoted CO2 electroreduction over indium-doped SnP3: A computational study

2020 It is generally considered that the hydrogenation of CO2 is the critical bottleneck of the CO2 electroreduction. In this work, with the aid of density functional theory (DFT) calculations, the catalytic hydrogenation of CO2 molecules over Indium-doped SnP3 catalyst were systematically studied. Through doping with indium (In) atom, the energy barrier of CO2 protonation is reduced and OCHO* species could easily be generated. This is mainly due to the p orbital of In exhibits strong hybridization with the p orbital of O, indicating that there is a strong interaction between OCHO* and In-doped SnP3 catalyst. As a result, In-doped SnP3 possesses high-efficiency and high-selectivity for converting CO2 into HCOOH with a low limiting potential of −0.17 V. Our findings will offer theoretical guidance to CO2 electroreduction

Necklace-like carbon nanofibers encapsulating V3S4 microspheres for ultrafast and stable potassium-ion storage

2020 The Royal Society of Chemistry. Potassium-ion batteries (PIBs) are promising candidates for scalable energy storage devices due to their low cost, high operating voltage and fast ionic conductivity in electrolyte. However, the research progress of PIBs still faces great challenges due to the lack of suitable hosts for reversible depotassiation/potassiation of large size K+, thus leading to low reversible capacity and poor cycling stability and rate capability. Herein, we have rationally designed a new necklace-like V3S4/carbon composite composed of V3S4 microspheres encapsulated in N-doped carbon nanofibers (V3S4@NCNFs) as an advanced anode for PIBs. Benefiting from the remarkable ion/electronic conductivity, fast electron transport, structural integrity upon cycling, and significant pseudocapacitance contributions, the V3S4@NCNF electrodes exhibit a high reversible capacity of 445 mA h g-1 after 300 cycles at 0.2 A g-1, a prolonged cycling stability of 245 mA h g-1 capacity retention over 1000 cycles at 2 A g-1, and an excellent rate performance of 249/202 mA h g-1 at 5/10 A g-1, which are superior to those of most reported anode materials for PIBs

Metal Chalcogenides: Paving the Way for High-Performance Sodium/Potassium-Ion Batteries

The research of sodium/potassium-ion batteries (SIBs/KIBs) still has some way to go but its success could possibly radically alter the way electricity is stored and used. As the key part of battery technology, advances in electrode materials are instrumental in accelerating the uptake of these renewable and innovative storage solutions. This is where metal chalcogenides (MCs) that tick all the right boxes can fit in to fill the gap. In this review, an overview is provided on the recent progress of MCs, with an emphasis on nanostructured metal sulfides and selenides, and the impact that metal chalcogenides may have on the future of SIBs and KIBs technology is discussed by taking a glimpse at the diverse set of properties inherent in them. In addition, several promising strategies are highlighted to address the imminent challenges faced by MCs in SIBs and KIBs, hoping to cast an insightful outlook for possible future direction in this field

Synergistic Function between Phosphorus-Containing Flame Retardant and Multi-Walled Carbon Nanotubes towards Fire Safe Polystyrene Composites with Enhanced Electromagnetic Interference Shielding

As a universal polymer material, polystyrene (PS) is widely applied in electrical devices and construction. Thus, it is necessary to improve the flame retardancy and electromagnetic shielding properties of PS material. In this work, PS/silicon-wrapped ammonium polyphosphate/Inorganic acid-treated multi-walled carbon nanotubes composites (PS/SiAPP/aMWCNT, abbreviated as PAC) were prepared via methods of filtration-induced assembly and hot-pressing. Morphology and structure characterization demonstrated that SiAPP and aMWCNT had good dispersion in PS and excellent compatibility with the PS matrix. Thermogravimetric analysis revealed that the addition of aMWCNT to PS improved its thermal stability and carbon-forming characteristics. The peak heat release rate, the peak carbon monoxide production rate, and the peak smoke production rate of the PAC10 composite decreased by 53.7%, 41.9%, and 45.5%, respectively, while its electromagnetic shielding effectiveness reached 12 dB. These enhancements were attributed to the reason that SiAPP and aMWCNT synergistically catalyzed the char generation and SiAPP produced free radical scavengers and numbers of incombustible gases, which could decrease the oxygen concentration and retard the combustion reaction. Therefore, the assembled PS/SiAPP/aMWCNT system provides a new pathway to improve the flame retardant and electromagnetic shielding properties of PS

VOPO4⋅2H2O nanosheet cathode for enhanced sodium storage

Na-ion batteries (SIBs) are anticipated to capture a broad development space in the field of large-scale energy storage due to the abundant sodium resources. High-performance cathode materials are very critical. VOPO4⋅2H2O with a two-dimensional (2D) layered structure is a very promising candidate for SIBs because of its high working voltage and theoretical specific capacity. Herein, a simple one-step reflux method is designed to fabricate a cathode of VOPO4⋅2H2O nanosheets. It exhibits a high average operating potential of ∼3.5 V, remarkable specific capacity (e.g., 135 mAh g–1 at 0.05 C), favorable high current charge-discharge ability (e.g., 58 mAh g–1 even at 20 C) as well as extralong cyclability (e.g., 0.026% capacity fading rate for per cycle at 20 C during 1000 cycles). The kinetic analysis implies that the superior sodium storage performance is mainly benefiting from the advantages of unique nanosheet structure, accelerating the rapid Na-ion diffusion.Published versio

Interlaminar repairing and thermoforming properties of carbon fiber reinforced Vitrimer epoxy resin composites

The interlaminar repairing behavior and thermoforming capacity of new carbon fiber reinforced Vitrimer epoxy resin (V-CFRP) composite and corresponding mechanisms were studied. The results reveal that the glass transition temperature (Tg) of the new Vitrimer epoxy resin is 92.8 ℃, and it exhibits significant stress relaxation behavior at temperatures higher than Tg. The stress relaxation time exhibits a linear relationship with temperature; The hot-press repair behavior and thermoplastic molding ability of V-CFRP composites were studied using a three-point bending experiment. The hot-press repair study shows that hot pressing at 180-220 ℃ for 1.5-2.0 h and 5 MPa can achieve nearly 100% repair of interlaminar damage in the composite; The bending modulus and bending strength of V-CFRP composites is decreased by more than 80% after pre-heating at 180-220 ℃ for 5-30 min. The significant decrease of bending modulus means that V-CFRP composite is suitable for thermoforming process. Moreover, a V-CFRP part with three-dimensional structure is successfully prepared by thermoforming process under the conditions of 200 ℃, 5 MPa and 2 h, which confirms the thermoforming capacity of V-CFRP composites

Direct and indirect communicative styles : a study in sociopragmatics and intercultural communication based on interview discourse with Norwegian and Japanese business executives

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