Aqueous zinc-ion batteries (AZIBs) are considered promising alternatives to lithium-ion batteries (LIBs) owing to their cost efficiency and eco-friendliness. However, the instability of the electrode materials poses a significant obstacle to broader applications. Herein, the synthesis, characterization, and zinc-ion storage properties of a vanadium coordination structure (V-INA) that uses VO2+ as the coordination center and isonicotinic acid (INA) as the organic ligand have been reported. Characterization techniques confirmed that the spacious lattice spacing and larger pore structure of V-INA create an efficient and stable pathway for zinc-ion migration. Note that within the V-INA structure, both the -COO- and C=N groups act in tandem as redox-active centers as well as zinc-ion hosts, and the valence change of vanadium (V4+/V5+) in VO2+ boosts the capacity of the battery. Benefiting from unique advantages of materials, V-INA achieves an unprecedented stability with a capacity retention of 97.25% after 1500 cycles at 5 A g(-1) as well as still delivers 123 mAh g(-1) reversible capacity after 2000 cycles at 10 A g(-1) with a Coulombic efficiency of similar to 100%. This work can inspire the design of coordination structures containing multiple redox-active centers as cathode materials for high-performance rechargeable AZIBs.

Aqueous zinc-ion batteries (AZIBs) utilizing Mn-based cathodes have garnered considerable attention owing to their safe and cut-price nature. However, MnO2 cathodes face capacity degradation from MnO2 dissolution during cycling. Herein, 2-picolinic acid (2-PA) serves as the ligand to grow an Mn coordination supramolecular network (Mn-CSN) on the R-MnO2 (Ramsdellite MnO2) particles via a one-pot hydrothermal method. The obtained material is denoted as R-MnO2@Mn-CSN and used as cathode material. Systematic study shows Mn-CSN can suppress R-MnO2 dissolution in Mn2+-free electrolyte, enhancing R-MnO2@Mn-CSN cycle stability (64.23 % capacity retention after 100 cycles at 0.1 A g-1 and 5000 cycles at 5 A g-1 with almost 100 % coulombic efficiency). Simultaneously, the H+-dominated Zn2+/H+ co-insertion/extraction mechanism is verified in R-MnO2@Mn-CSN cathode. Moreover, coin cells with R-MnO2@Mn-CSN and 3 M ZnSO4 electrolyte achieve a max energy density of 413.7 Wh kg-1 and max power density of 6.40 kW kg-1. This work can inspire MnO2 cathode protection via CSNs for high-performance AZIBs, paving the way for their large-scale applications.

As a promising technology, aqueous zinc-ion batteries (ZIBs) represent a sustainable direction for future electrochemical energy storage systems. However, ZIBs have encountered a series of practical application problems, including the dissolution of the cathode material and sluggish kinetics, which eventuate rapid capacity decline and poor performance. In this study, we designed a novel cellulose separator modified by a hydrogen-bonded organic framework, which is called the FP/mHOF. FP/mHOF shows great performance, including suppressing capacity decay, boosting charge transfer kinetics, and mass transfer kinetics. FP/mHOF achieved stable cycling performance for 2000 cycles at the current density of 5 A g-1 and 850 cycles at 2 A g-1, whose capacity retention was up to 90.2 and 77.2%, respectively. As verified, HOF@FP shows great potential of being a next-generation separator for ZIBs.

Lithium‐sulfur (Li‐S) batteries are limited in practical application due to the dissolution and shuttle effect of lithium polysulfides (LiPSs) intermediates. Herein, a multifunctional Janus separator is designed that integrates the zirconium‐based coordination supramolecular network (Zr‐CSN) with the polypropylene (PP) membrane to fabricate Zr‐CSN@PP. The Zr‐CSN@PP constructs a barrier on the side of the sulfur cathode to block the passage of polysulfides, and the nanoporous structure of Zr‐CSN transfers lithium ions quickly. The active zirconium sites and abundant oxygen‐containing groups of Zr‐CSN adsorb and catalyze the polysulfides effectively, which has been proved by experiments and theoretical calculations. Zr‐CSN@PP promotes the migration of Li + (the lithium‐ion transference number is 0.63) and improves the kinetics of sulfur evolution reactions, enhancing the electrochemical performance of Li‐S batteries. The Li‐S battery with Zr‐CSN@PP separator has a capacity of 650.63 mAh g −1 after 280 cycles at 0.5 C (average decay of 0.2% per cycle), and a capacity of 422.48 mAh g −1 after 400 cycles at 2 C. This concept of porous coordination supramolecular networks Janus separator provides a broad prospect for advanced Li‐S batteries.

Lithium-sulfur batteries (LSBs) have attracted considerable attention due to their high capacity and energy density, however, the electrochemical performance of LSBs was limited by the difficult conversion of lithium polysulfides (LiPSs). Coordination supramolecular networks (CSNs) have flexible structures, abundant active sites, and intermolecular interactions, which can facilitate the transformation of LiPSs and ion/charge transport. Herein, we combined a zinc coordination supramolecular network (Zn-CSN) with MnO2 to synthesize Zn-CSN@MnO2via a one-pot method. Zn-CSN@MnO2 accelerates the evolution of LiPSs and promotes the migration of lithium ions. Zn-CSN@MnO2 as a sulfur host in LSBs displays outstanding rate performance (406.55 mAh g-1 at 4C). It has a high initial specific capacity of 1027.89 mAh g-1 at 0.5C, cycling 150 cycles with a capacity loss of 0.2% per cycle. Surprisingly, it runs 400 cycles at a high current density of 5C with a capacity retention of 80.5%. This synergistic strategy for CSNs and oxides has brightened the prospects of the practical applications of LSBs. Zinc coordination supramolecular network (Zn-CSN) combined with MnO2 to obtained the Zn-CSN@MnO2, Zn-CSN@MnO2 as a sulfur host achieves high-rate performance of lithium-sulfur batteries.

Prussian blue analogs (PBAs) have been considered as a kind of promising cathode materials, but its poor cycle performance severely hinders their industrialization. Herein, by combining a zinc ferrocyanide (ZnHCF) cathode with aqueous ZnSO4/LiTFSI electrolyte and zinc metal anode, we achieved a stable anion insertion-type aqueous dual-ion battery (DIB) which displays a discharge specific capacity of 75.9 mAh g–1, an energy density of 124 Wh kg–1, and a discharge plateau of 1.8 V at 5 A g–1. Its specific capacity can still reach 57.4 mAh g–1 after 1200 cycles with a Coulombic efficiency of 97 %. A reversible anion insertion mechanism of ZnHCF cathode based on the changes of the valency of iron and the insertion of TFSI– ion on crystal surface caused by electrostatic interaction is proposed and confirmed with a series of characterizations and density functional theory calculations (DFT). This work proposes the study of anion energy storage mechanism of PBAs and brings more opportunities for their large-scale applications in the future.

Aqueous zinc metal batteries (ZMBs) are a promising sustainable technology for large-scale energy storage applications. However, the water is often associated with problematic parasitic reactions on both anode and cathode, leading to the low durability and reliability of ZMBs. Here, a multifunctional separator for the Zn-V2 O5 batteries by growing the coordination supramolecular network (CSN:Zn-MBA, MBA = 2-mercaptobenzoic acid) on the conventional non-woven fabrics (NWF) is developed. CSN tends to form a stronger coordination bond as a softer cation, enabling a thermodynamically preferred Zn2+ to VO2+ substitution in the network, leading to the formation of VO2 -MBA interface, that strongly obstructs the VO2 (OH)2- penetration but simultaneously allows Zn2+ transfer. Moreover, Zn-MBA molecules can adsorb the OTF- and distribute the interfacial Zn2+ homogeneous, which facilitate a dendrite-free Zn deposition. The Zn-V2 O5 cells with Zn-MBA@NWF separator realize high capacity of 567 mAh g-1 at 0.2 A g-1 , and excellent cyclability over 2000 cycles with capacity retention of 82.2% at 5 A g-1 . This work combines the original advantages of the template and new function of metals via cation metathesis within a CSN, provides a new strategy for inhibiting vanadium oxide dissolution.

Iodine has great potential in the energy storage, but high solubility of I 3 − has seriously delayed its promotion. Benefited from abundant active sites and the open channel, two-dimensional coordination supramolecular networks (2D CSNs) is considered to be a candidate for the energy storage. Herein, a 2D porphyrin-CSN cathode named Zn-TCPP for aqueous iodine dual-ion battery (DIB) shows an excellent specific capacity of 278 mAh g −1 , and a high energy density of 340 Wh kg −1 at 5 A g −1 , as well as a durable cycle performance of 5000 cycles and a high Coulombic efficiency of 98 %. Molecular orbital theory, UV/VIS, Raman spectroscopy and density functional theory (DFT) calculations reveal charge-transfer interaction between the donor of porphyrin nitrogen and the acceptor of I 3 − , and computational fluid dynamics (CFD) simulations demonstrate the contribution of 2D layered network structure of Zn-TCPP to the penetration of I 3 − .

The search for high-energy and fast Li-ion transportation of lithium-ion battery (LIB) anode materials instead of graphite has aroused the wide attention of scientists. Coordination supramolecular networks (CSNs) are a class of active materials that can be used in energy storage devices because of their adjustable structural characteristics and various intermolecular forces. In this work, 1D-CoCSN {[Co3(stp)2(bpy)5(H2O)6]n} and 3D-CoCSN {[Co3(stp)2(bpy)(H2O)4]n} were synthesized by regulating the coordination reaction of 2-sulfoterephthalic acid monosodium salt (NaH2stp), 4,4 '- bipyridine (bpy), and cobalt ions. The X-ray photoelectron spectroscopy (XPS), ex situ Fourier transform infrared spectroscopy (FTIR), and density functional theory (DFT) analyses show that the carboxylic, sulfonic, and pyridine active groups of 1D-CoCSN are synergically involved in the storage process of lithium ions, and electrons could be transferred in the Z-shaped chain structure through the pi-d-pi conjugation effect. Hence, 1D-CoCSN exhibits a high capacity of 567 mAh g-1 after 200 cycles at 0.5 A g-1 and even runs 1000 cycles at 2 A g-1 with a capacity of 233 mAh g-1. Structural regulation of CSNs provides a new approach to designing LIB anodes with high capacity and stable cycling performance.

Rapid advances in mild aqueous zinc metal batteries (AZMBs) have provided broader prospects for energy storage. However, practical application of AZMBs is hampered by issues such as formation of dendrites, by-products and hydrogen evolution. Herein, we report a new type of zinc anodes coated with Coordination Supramolecular Networks (CSNs) of zinc dithiosalicylate (Zn-DTA) prepared by in-situ chemical growth. The Zn-DTA layer acts as a natural barrier to inhibit the two-dimensional diffusion of zinc ions on the surface, leading to the uniform deposition. Abundant active sites provided by the coordination network also effectively facilitates the rapid transport of zinc ions inside and improves the electrochemical kinetics. As a result, symmetrical cells assembled with Zn-DTA@Zn electrode exhibit prominent performance of working stably for 2000 h at 1 mA cm −2 . The zinc-copper cells operated for 2000 h while Coulombic efficiency closing to 100%. In addition, the Zn//V 2 O 5 full batteries reveal excellent rate performance and cycled for 1500 h at 2 A g −1 . We believe that introduction of the multifunctional CSNs can irritate new ideas for the design of anodes. The facile and efficient in-situ growth Zn-DTA coating also makes the scale application of AZMBs step forward.

Aqueous zinc-metal batteries (ZMBs) have stood out from other rechargeable metal batteries due to their high safety, low cost, and stability in neutral electrolytes. However, the capacity decay and sluggish kinetics of the cathode hinder further commercial application of ZMBs. Herein, we construct a novel vanadium coordination supramolecular network (V-CSN) via a facile one-step hydrothermal synthesis, as a cathode for aqueous ZMBs. The multiple active sites and dual energy storage mechanism originate from the redox of the vanadium oxygen center (V5+/V4+) and the donors on the ligand (carboxyl group and S atoms), which are synergistically involved in the storage of zinc ions, effectively enhancing the reversible cycle performance. Meanwhile, the large interplanar spacing, small band gap, and flexible CSN structure of V-CSN endowed it with fast kinetics and effectively hinder the dissolution of active materials. Consequently, the V-CSN cathode exhibits an outstanding rate capacity of 177.1 mA h g-1 at 0.2 A g-1 and ultra-long cycle lifespan of over 20 000 cycles at 5 A g-1 with a coulombic efficiency of & SIM;100 %. Moreover, density functional theory calculations reveal that the cathode has remarkable electrical conductivity and strong adsorption effect with zinc ions (& UDelta;Eads = -2.9 eV). This work offers a new insight into the construction of a CSN host with abundant active sites, providing a new strategy for the design of high-performance rechargeable aqueous ZMBs. A novel vanadium coordination supramolecular network was synthesized, and employed as the cathode for zinc metal batteries, and exhibit excellent rate performance and ultra-long cycle life.

The environmental benefit and cheapness of aqueous zinc metal batteries enable them to top scrutiny. But so far, their engagement for practical scenarios is subjected to chronic dendrite growth and water-induced parasitic reactions that can terribly impair the system. Herein, innocent polyvinylpyrrolidone (PVP) additive with well-suited qualitative filter paper separator to promote the electrochemical stability of zinc anode in Zn(CF 3 SO 3 ) 2 electrolyte. PVP regulates the zinc deposition behavior and mitigates the corrosion of Zn from the electrolyte by adsorption to the anode, leading to a dendrite-free and reversible (average Coulombic efficiency of 95.2%) zinc electrode. It is found that the C=O of PVP affords the zinc anode with excellent tolerance to high current density. Benefit from the protection of PVP, Zn||Zn symmetric cell realized highly reversible stripping/plating performance of over 500 h at 5 mA cm −2 . In addition, the feasibility is also verified by the high capacity-retention of Zn//V 2 O 5 (74.2% over 1000 cycles) and Zn//activated carbon cells (99.9% over 10000 cycles). The Zn protection strategy of combining cabbage-priced surfactant with low-cost qualitative filter paper provides a cost-effective solution for the commercial application of zinc electrode.

Iodine is considered to have broad application prospects in the field of electrochemical energy storage. However, the high solubility of I3- severely hampers its practical application, and the lack of research on the anchoring mechanism of I3- has seriously hindered the development of advanced cathode materials for iodine batteries. Herein, based on the molecular orbital theory, we studied the charge-transfer interaction between the acceptor of I3- with a σ* empty antibonding orbital and the donor of pyrimidine nitrogen with lone-pair electrons, which is proved by the results of UV-vis absorption spectroscopy, Raman spectroscopy, and density functional theory (DFT) calculations. The prepared dual-ion battery (DIB) exhibits a high voltage platform of 1.2 V, a remarkable discharge-specific capacity of up to 207 mAh g-1, and an energy density of 233 Wh kg-1 at a current density of 5 A g-1, as well as outstanding cycle stability (operating stably for 5000 cycles) with a high Coulombic efficiency of 97%, demonstrating excellent electrochemical performance and a promising prospect in stationary energy storage.

MOF materials offer highly eye-catching performance in supercapacitor applications, but the traditional ligands are relatively crude and limited in diversity, which fails to realize the full potential of MOFs. In order to probe the electrochemical possibilities of MOFs, we synthesize MOF materials based on N-containing melamine (MA) ligand and S-containing 2,5-thiophene dicarboxylic acid (TDA) ligand, and use a bimetal strategy to optimize materials properties. It is observed that the crystallinity and morphology of the materials have greatly improved after partially replacing the DMF with MeOH in the solvothermal reaction. The obtained Zn1Ni3-M electrode delivers a specific capacitance of 466.5 F g(-1 )at 0.5 A g(-1). Moreover, the assembled Zn1Ni3-M//activated carbon asymmetric supercapacitor (ASC) realizes a specific energy density of 9.55 Wh kg(- 1) and an excellent power density of 3600.0 W kg(-1). It is demonstrated that the prepared Zn1Ni3-M bimetallic MOF has considerable potential as ultrafast electrode material for supercapacitors.

Commercialization of aqueous zinc-metal batteries remains unrealistic due to the substantial dendrite growth and side reaction issues on the zinc anodes. It is highly demanded to develop easy-to-handle approaches for constructing stable, dense, as well as homogeneous solid anode/electrolyte interfaces. Herein, the authors construct the zinc anode interface with a close-packed Zn-TSA (TSA = thiosalicylate) coordination supramolecular network through the facile and up-scalable wet-chemical method. The hydrophobic Zn-TSA network can block solvated water and establish a solid-state diffusion barrier to well-distribute the interfacial Zn2+ , thus inhibiting hydrogen evolution and zinc dendrite growth on the anode. Meanwhile, the Zn-TSA network induces the formation of a uniform and stable solid electrolyte interphase composed of multiple inorganic-organic compounds. This denser structure can accommodate and self-heal the crack/degradation of the anode interphase associated with the repeated volume changes, and suppress the generation of detrimental by-product, Znx (OTF- )y (OH)2x-y ·nH2 O. Such a rationally fabricated anode/electrolyte interface further endows the assembled symmetric cells with superior plating/stripping stability for over 2000 h without dendrite formation (at 1 mA cm-2 and 1 mAh cm-2 ). Furthermore, this zinc anode has practical application in the Zn-MoS2 and Zn-V2 O5 full cells. This study provides a new train of thought for constructing the dense interface of zinc-metal anode.

Aqueous Zn-ion batteries (ZIBs) are considered very promising alternatives to lithium-ion batteries. However, the low reversibility and slow diffusion of zinc ions in the positive electrode limit their commercial applications. Herein, we successfully prepared the metallic 1T phase of MoS2 (1T-MoS2) with a nano interlayer spacing of 1.025 nm through a simple one-step hydrothermal method, and used it as a cathode in ZIBs. By adjusting the hydrothermal temperature, the crystallinity and Zn2+ storage capacity of MoS2 as a cathode for ZIBs are effectively improved. MoS2 had the most favorable structure when the hydrothermal temperature was 200 °C, such as larger layer spacing and more lattice distortion. When employed as a cathode, 200-MoS2 exhibited a considerable specific capacity of 125 mA h g-1 at the current density of 2 A g-1 and high capacity retention of 100% after 500 cycles. This strategy provides a new option for improving the performance of the layered structure as an aqueous zinc ion battery.

The carbon nanotube (CNT) cold cathode can provide a high current and current density for microwave devices, which normally work under pulse mode. In this work, we studied the electron emission characteristics and strucutre stability of a CNT cold cathode in millisecond pulse mode. Peak current and average current are both key parameters for the performance of cold cathode. Increasing the duty ratio proved an effective way to increase the average current and average power of the cold cathode. The pulsing field emission characteristics of CNT cold cathode was optimized by modulating the pulse width, pulse interval time, and duty ratio. The average current in millisecond pulse mode was three orders of magnitude greater than that when using microsecond pulses. The average current also linearly increased with the duty ratio. The morphology of CNT films after pulsing and DC field emission was investigated to reveal the stability and the vacuum breakdown mechanism. The thermal equilibrium of the CNT was analyzed to reveal its underlying mechanism. This work provides a practical strategy for the application of CNT cold cathodes in high-power microwave devices.

The epitaxial growth of carbon nanotubes (CNTs) is an important subject of research. Recent attention has been paid to finding new strategies for the controlled growth of single-wall CNTs with a defined chirality. In addition, many potential applications require multiwall CNTs (MWCNTs) to grow vertically from the substrate and the interface property is crucial. Here, we report for the first time that MWCNTs can grow directly from the surface of a substrate by epitaxy, based on the experimental study of individual multiwall carbon nanotubes on a largearea stainless steel substrate, which is a very useful system for electrical and mechanical applications. In particular, evidence is given of the lattice matching between the MWCNT and the lattice of a hexagonal Cr2O3: (Fe, Mn) film formed on the surface of the substrate. Furthermore, a method is developed to increase the density of the MWCNTs; a mechanism of simultaneous top and bottom growth is proposed. The resultant significantly improved electrical transport and field emission properties are also presented, showing the Ohmic contact for electrical conduction and high performance in resisting the catastrophic cold-cathode vacuum breakdown of the CNTs.

Most of applications based on cold cathode work in pulse driving mode. It is reported here that the field electron emission characteristics from carbon nanotube cold cathode by driving millisecond width pulse voltage is investigated. A peak emission current of 5.06 mA with the current density of 253 mA/cm2 is obtained from 0.02 cm2 carbon nanotubes film by driving 1 ms width with 10 Hz frequency pulse voltage, and it is about twice larger than the maximum current (~2.5 mA) in continuous voltage. The relation between the emission current and pulsed width is also studied, showing that the peak emission current vary hardly with changing the pulse width with a constant frequency.