An energy storage principle using bipolar porous polymeric frameworks

Packed with energy: Amorphous covalent triazine-based frameworks were used as a cathode material, with the aim of developing an energy storage principle that can deliver a 2-3 times higher specific energy than current batteries with a high rate capability. The material undergoes a unique Faradaic reaction, as it can be present in both a p-doped and an n-doped state (see picture).     

Architected porous metals in electrochemical energy storage

Porous metallic structures are regularly used in electrochemical energy storage (EES) devices as supports, current collectors, or active electrode materials. Bulk metal porosification, dealloying, welding, or chemical synthesis routes involving crystal growth or self-assembly, for example, can sometimes provide limited control of porous length scale, ordering, periodicity, reproducibility, porosity, and surface area. Additive manufacturing has shown the potential to revolutionize the fabrication of architected metals, allowing complex geometries not usually possible by traditional methods, by enabling complete design freedom of a porous metal based on the required physical or chemical property to be exploited. We discuss properties of porous metal structures in EES devices and provide some opinions on how architected metals may alleviate issues with electrochemically active porous metal current collectors, and provide opportunities for optimum design based on electrochemical characteristics required by batteries, supercapacitors or other electrochemical devices.     

A hierarchical porous carbon membrane from polyacrylonitrile/polyvinylpyrrolidone blending membranes: Preparation,characterization and electrochemical capacitive performance

Novel hierarchical porous carbon membranes were fabricated through a simple carbonization procedure of well-defined blending polymer membrane precursors containing the source of carbon polyacrylonitrile (PAN) and an additive of polyvinylpyrrolidone (PVP), which was prepared using phase inversion method. The as-fabricated materials were further used as the active electrode materials for supercapacitors. The effects of PVP concentration in the casting solution on structure feature and electrochemical capacitive performance of the as-prepared carbon membranes were also studied in detail. As the electrode material for supercapacitor, a high specific capacitance of 278.0 F/g could be attained at a current of 5 mA/cm² and about 92.90% capacity retention could be maintained after 2000 charge/discharge cycles in 2 mol/L KOH solution with a PVP concentration of 0.3 wt% in the casting solution. The facile hierarchical pore structure preparation method and the good electrochemical capacitive performance make the prepared carbon membrane particularly promising for use in supercapacitor.     

A hierarchical porous carbon membrane from polyacrylonitrile/polyvinylpyrrolidone blending membranes:Preparation,characterization and electrochemical capacitive performance

Novel hierarchical porous carbon membranes were fabricated through a simple carbonization procedure of well-defined blending polymer membrane precursors containing the source of carbon polyacrylonitrile （PAN） and an additive of polyvinylpyrrolidone （PVP）, which was prepared using phase inversion method. The as-fabricated materials were further used as the active electrode materials for supercapacitors. The effects of PVP concentration in the casting solution on structure feature and electrochemical capacitive performance of the as-prepared carbon membranes were also studied in detail. As the electrode material for supercapacitor, a high specific capacitance of 278.0 F/g could be attained at a current of 5 mA/cm2 and about 92.90% capacity retention could be maintained after 2000 charge/discharge cycles in 2 mol/L KOH solution with a PVP concentration of 0.3 wt% in the casting solution. The facile hierarchical pore structure preparation method and the good electrochemical capacitive performance make the prepared carbon membrane particularly promising for use in supercapacitor.     

Ti3C2Tx MXene compounds for electrochemical energy storage

Since their discovery in 2011, MXene compounds, and in particular the Ti₃C₂-based phases, have gained increasing interest from researchers leading to over 2000 scientific works in 2020. The peculiar morphological, charge transport, and surface properties make the MXenes ideal materials for energy storage applications such as active material in alkaline ion batteries and supercapacitors, as conductive or buffer agent in composite electrodes for high energy applications, and as electrocatalytic materials for oxygen evolution or redox flow batteries. Among this almost endless literature, this work focuses on 5 recent articles (2019/2020) that summarize the potential of MXenes in different energy storage applications, also resuming the most promising preparatory routes regarding industrial scalability.     

金属改性与碳包覆的多孔硅微球复合材料的制备及其电化学储锂性能

以工业级SiAl合金微球为前驱物,采用多步刻蚀-热处理策略,制备了金属(Sb-Sn)改性与碳包覆的多孔硅微球复合材料(pSi/Sb-Sn@C)。pSi/Sb-Sn@C具有以 Sb-Sn改性的多孔硅微球(pSi/Sb-Sn)为核、碳包覆层为壳的三维结构。碳外壳可以提高多孔硅微球的电子导电性和机械稳定性,有利于获得稳定的固体电解质界面(SEI)膜;而三维多孔核可以促进锂离子的扩散,增加嵌/脱锂活性位,缓冲嵌锂过程中的体积膨胀。此外,活性金属(Sb-Sn)的引入能够提高复合材料的导电性,并可以贡献一定的储锂容量。由于其特殊的组成和独特的微观结构,pSi/Sb-Sn@C复合材料在1.0 A·g^-1电流密度下充放电300次后的可逆容量为1 247.4 mAh·g^-1,显示了良好的高速率储锂性能和优异的电化学嵌/脱锂循环稳定性。     

Sodium‐Doped Mesoporous Ni2P2O7 Hexagonal Tablets for High‐Performance Flexible All‐Solid‐State Hybrid Supercapacitors

A simple hydrothermal method has been developed to prepare hexagonal tablet precursors, which are then transformed into porous sodium‐doped Ni₂P₂O₇ hexagonal tablets by a simple calcination method. The obtained samples were evaluated as electrode materials for supercapacitors. Electrochemical measurements show that the electrode based on the porous sodium‐doped Ni₂P₂O₇ hexagonal tablets exhibits a specific capacitance of 557.7 F g^?1 at a current density of 1.2 A g^?1. Furthermore, the porous sodium‐doped Ni₂P₂O₇ hexagonal tablets were successfully used to construct flexible solid‐state hybrid supercapacitors. The device is highly flexible and achieves a maximum energy density of 23.4 Wh kg^?1 and a good cycling stability after 5000 cycles, which confirms that the porous sodium‐doped Ni₂P₂O₇ hexagonal tablets are promising active materials for flexible supercapacitors.     

Facile Synthesis of A 3D Flower‐Like Mesoporous Ni@C Composite Material for High‐Energy Aqueous Asymmetric Supercapacitors

A 3D flower‐like mesoporous Ni@C composite material has been synthesized by using a facile and economical one‐pot hydrothermal method. This unique 3D flower‐like Ni@C composite, which exhibited a high surface area (522.4 m² g^?1), consisted of highly dispersed Ni nanoparticles on mesoporous carbon flakes. The effect of calcination temperature on the electrochemical performance of the Ni@C composite was systematically investigated. The optimized material (Ni@C 700) displayed high specific capacity (1306 F g^?1 at 2 A g^?1) and excellent cycling performance (96.7 % retention after 5000 cycles). Furthermore, an asymmetric supercapacitor (ASC) that contained Ni@C 700 as cathode and mesoporous carbon (MC) as anode demonstrated high energy density (60.4 W h kg^?1 at a power density of 750 W kg^?1).     

Activated carbon derived from marine Posidonia Oceanica for electric energy storage

In this paper, the synthesis and characterization of activated carbon from marine Posidonia Oceanica were studied. The activated carbon was prepared by a simple process namely pyrolysis under inert atmosphere. The activated carbon can be used as electrodes for supercapacitor devices. X-ray diffraction result revealed a polycrystalline graphitic structure. While scanning electron microscope investigation showed a layered structure with micropores. The EDS analysis showed that the activated carbon contains the carbon element in high atomic percentage. Electrochemical impedance spectroscopy revealed a capacitive behavior (electrostatic phenomena). The specific capacity per unit area of the electrochemical double layer of activated carbon electrode in sulfuric acid electrolyte was 3.16 F cm⁻². Cyclic voltammetry and galvanostatic chronopotentiometry demonstrated that the electrode has excellent electrochemical reversibility. It has been found that the surface capacitance was strongly related to the specific surface area and pore size.     

High-performance nitrogen and sulfur co-doped nanotube-like carbon anodes for sodium ion hybrid capacitors

Sodium ion hybrid capacitors are of great concern in large-scale and cost-effective electrical energy storage owing to their high energy and power densities, as well as natural abundance and wide distribution of sodium. However, it is difficult to find a well-pleasing anode material that matches the high-performance cathode materials to achieve good energy and power output for sodium ion hybrid capacitors. In this paper, nitrogen and sulfur co-doped nanotube-like carbon prepared by a simple carbonization process of high sulfur-loaded polyaniline nanotubes is introduced as the anode. The assembled sodium ion half cell based on the optimal nanotube-like carbon delivers a high reversible capacity of ∼304.8 mAh/g at 0.2 A/g and an excellent rate performance of ∼124.8 mAh/g at 10 A/g in a voltage window of 0.01–2.5 V (versus sodium/sodium ion). For the hybrid capacitors assembled using the optimal nanotube-like carbon as the anode and high-capacity activated carbon as the cathode, high energy densities of ∼100.2 Wh/kg at 250 W/kg and ∼50.69 Wh/kg at 12,500 W/kg are achieved.     

Synthesis of 2D/2D Structured Mesoporous Co3O4 Nanosheet/N‐Doped Reduced Graphene Oxide Composites as a Highly Stable Negative Electrode for Lithium Battery Applications

Mesoporous Co₃O₄ nanosheets (Co₃O₄‐NS) and nitrogen‐doped reduced graphene oxide (N‐rGO) are synthesized by a facile hydrothermal approach, and the N‐rGO/Co₃O₄‐NS composite is formulated through an infiltration procedure. Eventually, the obtained composites are subjected to various characterization techniques, such as XRD, Raman spectroscopy, surface area analysis, X‐ray photoelectron spectroscopy (XPS), and TEM. The lithium‐storage properties of N‐rGO/Co₃O₄‐NS composites are evaluated in a half‐cell assembly to ascertain their suitability as a negative electrode for lithium‐ion battery applications. The 2D/2D nanostructured mesoporous N‐rGO/Co₃O₄‐NS composite delivered a reversible capacity of about 1305 and 1501 mAh g^?1 at a current density of 80 mA g^?1 for the 1st and 50th cycles, respectively. Furthermore, excellent cyclability, rate capability, and capacity retention characteristics are noted for the N‐rGO/Co₃O₄‐NS composite. This improved performance is mainly related to the existence of mesoporosity and a sheet‐like 2D hierarchical morphology, which translates into extra space for lithium storage and a reduced electron pathway. Also, the presence of N‐rGO and carbon shells in Co₃O₄‐NS should not be excluded from such exceptional performance, which serves as a reliable conductive channel for electrons and act as synergistically to accommodate volume expansion upon redox reactions. Ex‐situ TEM, impedance spectroscopy, and XPS, are also conducted to corroborate the significance of the 2D morphology towards sustained lithium storage.     

The loading of polyoxometalates compound on a biomass derived N-doped mesoporous carbon matrix,a composite material for electrical energy storage

Abstract

A polyoxometalate (POM)-based composite material (NiPW₁₂NP/NMC) was synthesized, in which the nanoparticle of a POM compound (NiPW₁₂NP) distributes on orange juice derived nitrogen doped mesoporous carbon matrix (NMC) homogenously. When employed as a cathode material, NiPW₁₂NP/NMC exhibits high specific capacitance, remarkable rate capability and long-term stability. When the current density is 4?A·g^?1, a specific capacitance as high as 547 F·g^?1 is achieved by NiPW₁₂NP/NMC. With NiPW₁₂NP/NMC serving as cathode and MnO₂ acting as anode, a high performance asymmetric supercapacitor is assembled, which possesses a high energy density of 10.88?Wh·kg^?1 at 0.64?kW·kg^?1. It also shows a good rate capability, when the current density increases from 4 to 12?A·g^?1, its specific capacitance decreases from 113 to 88 F·g^?1, with 77.9% capacitance retention. After 5000 cycles charge-discharge experiments, 92.8% of its capacitance can be maintained, which exhibits good stability.     

Large-scale Ni-MOF derived Ni_3S_2 nanocrystals embedded in N-doped porous carbon nanoparticles for high-rate Na~+ storage

Metal organic framework(MOF) has been confirmed as the promising precursor to develop the conve rsion-typed anode mate rials of sodium-ion batteries(SIBs) because of the tunable structure design and simple functional modification.Here,we prepare the ultrasmall Ni_3S_2 nanocrystals embedded into N-doped porous carbon nanoparticles using the scalable Ni-MOF as precursor(denoted as Ni_3S_2@NPC).The ultrasmall size of Ni_3S_2 can work for accelerated electro n/ion transfer to facilitate the electrochemical reaction kinetics.Moreover,the robust conductivity network originated from N-doped porous carbon nanoparticles can not only improve the electron conductivity,but also enhance the electrode integrity and stability of the electrode/electrolyte interface.In addition,the N heteroatoms provide extra Na storage sites.Accordingly,the electrode delivers the obviously competitive capacities and high-power output with respect to the currently reported Ni_3S_2/C composites.This study provides a scalable and universal strategy to develop the advanced transition metal sulfides for practically feasible SIBs.     

A mesoporous 3D hybrid material with dual functionality for Hg2+ detection and adsorption

Dual-function hybrid material U1 was designed for simultaneous chromofluorogenic detection and removal of Hg(2+) in an aqueous environment. Mesoporous material UVM-7 (MCM41 type) with homogeneously distributed pores of about 2-3 nm in size, a large specific surface area exceeding 1000 m(2) g(-1), and nanoscale particles was used as an inorganic support. The mesoporous solid is decorated with thiol groups that were treated with squaraine dye III to give a 2,4-bis(4-dialkylaminophenyl)-3-hydroxy-4-alkylsulfanylcyclobut-2-enone (APC) derivative that is covalently anchored to the inorganic silica matrix. The solid was characterised by various techniques including X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and nitrogen adsorption. This hybrid solid is the chemodosimeter for Hg(2+) detection. Hg(2+) reacts with the APC fragment in U1 with release of the squaraine dye into the solution, which turns deep blue and fluoresces strongly. Naked-eye Hg(2+) detection is thus accomplished in an easy-to-use procedure. In contrast, U1 remains silent in the presence of other thiophilic transition metal ions, alkali and alkaline earth metal ions, or anions ubiquitously present in water such as chloride, carbonate, sulfate, and phosphate. Material U1 acts not only as chemodosimeter that signals the presence of Hg(2+) down to parts-per-billion concentrations, but at the same time is also an excellent adsorbent for the removal of mercury cations from aqueous solutions. The amount of adsorbed mercury ranges from 0.7 to 1.7 mmol g(-1), depending on the degree of functionalisation. In addition, hybrid material U1 can be regenerated for both sensing and removal purposes. As far as we know, U1 is the first example of a promising new class of polyfunctional hybrid supports that can be used as both remediation and alarm systems by selective signalling and removal of target species of environmental importance. Model compounds based on silica gel (G1), fumed silica (F1), and micrometre-sized MCM-41 scaffolds (M1) were also prepared and studied for comparative purposes.     

Recent advances of transition metal oxalate-based micro- and nanomaterials for electrochemical energy storage: a review

A key challenge in the development of electrochemical energy storage (EES) is the design and engineering of electrode materials for electrochemical reactions. Transition metal oxalates (TMOxs) have been widely used in various EES applications due to their low cost, simple synthesis, and excellent electrochemical performance. In this review, the recent advances in the design and engineering of transition metal oxalate-based micro- and nanomaterials for EES are summarized. Specifically, the survey will focus on three types of micro- and nano-scale TMOxs (monometallic, bimetallic, and trimetallic TMOxs), their composites (TMOx-metal oxide, TMOx-hydroxide, TMOx-GO, and TMOx-MOFs composites), and derivatives, including transition metal oxides (TiO₂, V₂O₅, Mn_xO_y, Co₃O₄, NiO, CuO, and Nb₂O₅), multi-transition metal oxides (MCo₂O₄ (M = Ni, Cu, and Zn), NiMn₂O₄, and N_xO_y-M_xO_y), transition metal sulfide (NiS₂), and carbon materials (ordinary carbon, GO and their composites), within the context of their intrinsic structure and corresponding electrochemical performance. A range of experimental variables will be carefully analyzed, such as sample synthesis, crystal structure, and electrochemical reaction mechanism. The applications of these materials as EES electrodes are then featured for supercapacitors (SCs) and lithium-ion batteries (LIBs). We conclude the review with a perspective of future research prospects and challenges.     

Natural nanomaterial as hard template for scalable synthesizing holey carbon naonsheet/nanotube with in-plane and out-of-plane pores for electrochemical energy storage

By tuning the structure of hard template kaolinite, we have achieved a template directed synthesis of holey carbon nanosheet/nanotube material. This carbon nanomaterial with in-plane and out-of-plane pores has shown promising electrochemical energy storage capacity.