Flexible Zn Research Articles

Structural design of FeCo alloy implanted into N,S co-doped carbon nanotubes via self-catalyzed growth for advanced liquid and flexible all-state-state Zn-air battery.

The introduction of transition bimetallic alloys can effectively improve oxygen reduction reaction (ORR) activity. However, the alloy particles are inclined to dissolve under harsher conditions, resulting in a serious decrease in catalytic activity and stability. Herein, an efficient ORR catalyst, FeCo alloy nanoparticles (NPs) encapsulated in N,S co-doped carbon nanotubes (FeCo10-NSCNTs), was developed through a self-catalyzed growth strategy. Due to the delicate structural design, the N,S co-doped structure can effectively improve the ORR performance by modulating the electronic properties and surface polarity of the carbon substrate, and the randomly connected carbon nanotube structure with large specific surface area can further enhance the adsorption and dissociation of gas molecules, accelerating the kinetics of gas participation in the reaction. Carbon-encapsulated FeCo alloys are beneficial for improving catalytic activity and durability. The FeCo10-NSCNTs displayed excellent ORR activity with a half-wave potential of E1/2 = 0.84 V and robust stability of 13 k cycles. More impressively, the assembled liquid-state Zn-air battery (ZAB) with FeCo10-NSCNTs as the air-electrode delivers an output power density of 146.68 mW cm-2 along with excellent operation durability. The assembled all-solid ZAB has good cyclic stability under 0-180° bending conditions. The synthesized N,S co-doping, carbon nanotubes and FeCo alloys provide important guidance for the construction of cheap non-noble metal-carbon hybrid nanomaterials.

Boosting oxygen reduction of well-dispersed CoP/V(PO3)3 sites via geometric and electronic engineering for flexible Zn–air batteries

A well-dispersed CoP/V(PO3)3 on hollow carbon spheres was fabricated using bi-surfactant tactics and phosphating treatment, and it exhibited a prominent ORR activity for aqueous/flexible Zn–air batteries with a high power density and extremely long life.

MXene-Boosted Imine Cathodes with Extended Conjugated Structure for Aqueous Zinc-Ion Batteries.

Organic molecules have been considered promising energy-storage materials in aqueous zinc-ion batteries (ZIBs), but are plagued by poor conductivity and structural instability because of the short-range conjugated structure and low molecular weight. Herein, an imine-based tris(aza)pentacene (TAP) with extended conjugated effects along the CN backbones is proposed, which is in situ injected into layered MXene to form a TAP/Ti3 C2 Tx cathode. Theoretical and electrochemical analyses reveal a selective H+ /Zn2+ co-insertion/extraction mechanism in TAP, which is ascribed to the steric effect on the availability of active CN sites. Moreover, Ti3 C2 Tx , as a conductive scaffold, favors fast Zn2+ diffusion to boost the electrode kinetics of TAP. Close electronic interactions between TAP and Ti3 C2 Tx preserve the structural integrity of TAP/Ti3 C2 Tx during the repeated charge/discharge. Accordingly, the TAP/Ti3 C2 Tx cathode delivers a high reversible capacity of 303 mAh g-1 at 0.04 A g-1 in aqueous ZIBs, which also realizes an ultralong lifetime over 10000 cycles with a capacity retention of 81.6%. Furthermore, flexible Zn||TAP/Ti3 C2 Tx batteries with a quasi-solid-state electrolyte demonstrate potential application in wearable electronic devices. This work offers pivotal guidance to create highly stable organic electrodes for advanced ZIBs.

Direct 3D printing of stress-released Zn powder anodes toward flexible dendrite-free Zn batteries

The notorious dendrite growth and poor deformation endurance of Zn metal anode impede the on-going rapid development of flexible Zn-ion batteries (ZIBs). Herein, a direct 3D printing approach architecting a novel Ag-anchored hierarchical porous flexible Zn anode (3DP-ZA) is for the first time proposed for flexible dendrite-free ZIBs. The 3DP-ZA anode demonstrates excellent inherent mechanical flexibility and structural stability: (1) the interaction between the components in the formulated ink (CNT, graphene and cellulose) drives an assembly of a robust intertwined flexible network where Zn powder is homogeneously embedded; (2) the 3D-printing customized macro holes guarantee sufficient buffer space for stress relief to accommodate volume change and maintain structural integrity upon plating/striping. Moreover, the introduced zincophilic Ag source and hierarchical porous structure of the anode endow uniform electronic/ionic fluxes and homogeneous Zn growth. Consequently, the 3DP-ZA//3DP-ZA symmetrical cell delivers a superior lifespan of over 330 h at 1 mA cm−2 and 1 mAh cm−2 with a low voltage hysteresis of 35 mV. Furthermore, a flexible full cell adopting 3DP-ZA anode and PANI coated carbon cloth (PANI@CC) cathode exhibits stable electrochemical performance under continuous deformation. This work points to a new mindset that elaborate 3D structural electrode design for high-performance flexible Zn batteries could be readily realized by 3D printing, which caters to a broad range of flexible energy storage applications.

Flexible zinc ion hybrid supercapacitors enabled by N/S co-doped porous carbon and bacterial cellulose/ZnSO4 electrolyte

Zinc-ion hybrid capacitors (ZHSCs), as a novel energy storage devices with battery type anode, capacitive type cathode, have attached widely attention. Herein, N, S co-doping porous carbon (NSC) is synthesized by a salt template assisted freeze drying method. Bacterial cellulose (BC)/ZnSO4 electrolyte is prepared by impregnating BC membrane into ZnSO4 solution. Thanks to significant cathode material, favorable flexible electrolyte system, and rational device design, the flexible Zn//BC/ZnSO4//NSC ZHSC device presents excellent electrochemical performance, including an excellent specific capacity of 113 mA h g−1 and a high energy density of 90.8 W h kg−1 at 0.5 A g−1, a superior cycling stability with excellent capacity retention of 93.9% over 10000 cycles at 5 A g−1. Impressively, NSC-6 based ZHSC device shows similar capacitive behavior under various bending states, demonstrating its excellent flexibility and stability. Overall, the ZHSC devices based on NSC cathode and BC/ZnSO4 flexible electrolyte are promising to be applied in portable, flexible, and wearable electronics.

Supramolecular Polymer Intertwined Free-Standing Bifunctional Membrane Catalysts for All-Temperature Flexible Zn–Air Batteries

HighlightsRational design of 3D flexible free-standing membrane catalysts with protonation between supramolecular polymers and nitrogen-deficient carbon nitride nanotubes frameworks via facile bottom-up self-conversion approach.PEMAC@NDCN demonstrates the lowest reversible oxygen bifunctional activity of 0.61 V with exceptional long-lasting durability, surpassing the commercial and reported champion oxygen catalysts.Engineering catalytically active cathode materials enabled all-temperature flexible Zn–air batteries with high electrochemical and mechanical performances (temperature of − 40 to 70 °C) under harsh operations.

Double-Faced Atomic-Level Engineering of Hollow Carbon Nanofibers as Free-Standing Bifunctional Oxygen Electrocatalysts for Flexible Zn-Air Battery.

Flexible solid-state zinc-air batteries (ZABs) with low cost, excellent safety, and high energy density has been considered as one of ideal power sources for portable and wearable electronic devices, while their practical applications are still hindered by the kinetically sluggish cathodic oxygen reduction and oxygen evolution reactions (ORR/OER). Herein, a Janus-structured flexible free-standing bifunctional oxygen electrocatalyst, with OER-active O, N co-coordinated Ni single atoms and ORR-active Co3O4@Co1-xS nanosheet arrays being separately integrated at the inner and outer walls of flexible hollow carbon nanofibers (Ni-SAs/HCNFs/Co-NAs), is reported. Benefiting from the sophisticated topological structure and atomic-level-designed chemical compositions, Ni-SAs/HCNFs/Co-NAs exhibits outstanding bifunctional catalytic activity with the ΔE index of 0.65 V, representing the current state-of-the-art flexible free-standing bifunctional ORR/OER electrocatalyst. Impressively, the Ni-SAs/HCNFs/Co-NAs-based liquid ZAB show a high open-circuit potential (1.45 V), high capacity (808 mAh g-1 Zn), and extremely long life (over 200 h at 10 mA cm-2), and the assembled flexible all-solid-state ZABs have excellent cycle stability (over 80 h). This work provides an efficient strategy for developing high-performance bifunctional ORR/OER electrocatalysts for commercial applications.

Novel Organic Cathode with Conjugated N-Heteroaromatic Structures for High-Performance Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) are being considered new choices of batteries not only because of their inherent safety but also because of their low price advantage. Nevertheless, it is still an important task to develop organic cathode materials with green sustainability and high performance. Hexaazatriphenylene (HAT)-based organic materials have shown great potential for use in AZIBs. Herein, 5,6,11,12,17,18-hexaazatrinaphthylene-2,8,14-tricarboxylic acid (HATTA) is designed and prepared as the AZIB cathode. Benefiting from the conjugative effect of -COOH, extended π-conjugated structure, and abundant active sites, the HATTA electrode exhibits a high capacity (225.8 mA h g-1 at 0.05 A g-1), an outstanding rate performance (136.1 mA h g-1 at 25 A g-1), and a long-term cycling lifespan (84.07% of the initial capacity after 10,000 cycles at 25 A g-1). Meanwhile, the characterization results of ex situ spectroscopic tests prove that the unsaturated bond (C═N) is the redox-active moiety of HATTA. In addition, the flexible Zn//HATTA battery also exhibits impressive long-term cycling stability and good flexibility, showing its promising application in wearable electronics. This work provides a strategy with rational designing for constructing high-performance AZIBs with organics.

3D Co3O4‐RuO2 Hollow Spheres with Abundant Interfaces as Advanced Trifunctional Electrocatalyst for Water‐Splitting and Flexible Zn–Air Battery

AbstractExploiting efficient and stable electrocatalysts with trifunctional catalytic activity toward hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) act has a crucial role with sustainable energy development. Therefore, this study fabricates Co3O4‐RuO2 hollow spheres using a facile and eco‐friendly solvothermal and low temperature oxidation procedure followed by ice water treatment (IW‐Co3O4‐RuO2‐HS). The specific hollow nanostructure could provide sufficient active sites and channels in the electrocatalytic procedure. Then, the IW‐Co3O4‐RuO2‐HS presents small overpotentials toward HER (40 mV@ 10 mA cm−2) and OER (250 mV@ 10 mA cm−2), and high half‐wave potential for ORR (E1/2@ 0.79 V). Remarkably, the IW‐Co3O4‐RuO2‐HS also presents superior catalytic performances toward water‐splitting and flexible rechargeable Zn–air batteries. Furthermore, the water electrolysis can be driven by sustainable energy, including solar, wind, thermal energy, and the assembled flexible rechargeable Zn–air battery. This study provides a valid path to synthesize multifunctional electrocatalysts on energy‐related devices.

Cobalt phosphosulfide nanoparticles encapsulated into heteroatom-doped carbon as bifunctional electrocatalyst for Zn−air battery

CoPS nanoparticles encapsulated with S, P, N tri-doped carbon material (SPNC) were proposed as bifunctional electrocatalyst of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) derived from zeolitic imidazolate framework-67. Density functional theory calculations consistently revealed that P element in CoPS@SPNC improves the electrical conductivity and reduces OH∗ hydrogenation energy barrier on Co sites, thereby facilitating the overall ORR/OER activities. A flexible Zn–air battery with CoPS@SPNC delivered an overpotential of 0.49 ​V, an energy efficiency above 80%, and a discharge voltage of 1.29 ​V at 2 ​mA ​cm −2 for 80 ​h. Cobalt phosphosulfide (CoPS) nanoparticles encapsulated with S, P, N tri-doped carbon (SPNC) is proposed as bifunctional electrocatalyst of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) derived from zeolitic imidazolate framework-67. A flexible Zn–air battery with CoPS@SPNC delivers a low overpotential of 0.49 ​V, a high energy efficiency above 80%, and a stable discharge voltage of 1.29 ​V at 2 ​mA ​cm −2 for 80 ​h.

Antifreezing Zwitterionic-Based Hydrogel Electrolyte for Aqueous Zn Ion Batteries

Hydrogel electrolytes have attracted great attention because the properties of integrated conductivity and mechanical flexibility endow them with potential applications in flexible solid-state batteries. However, hydrogels are easy to freeze when the temperature drops below zero, resulting in the reduction of ionic conductivity and mechanical strength of hydrogels. Herein, an antifreezing polymer hydrogel electrolyte was developed by introducing a zwitterionic group and salt into the double-network polymer. The polymer hydrogel electrolyte possessed a perfect ionic conductivity of 10.38 mS cm–1 at −20 °C and could remain unfrozen until −50 °C. A flexible solid-state Zn//LiFePO4 battery assembled with the prepared hydrogel electrolyte exhibited a discharge capacity of 126.1 and 75.1 mAh g–1 at 20 and −20 °C at 1 C, respectively. In addition, it showed quite perfect cycling performance and maintained a capacity retention of 72.6% after 1000 cycles with a favorable Coulombic efficiency (∼100%) at −20 °C at 1 C. The hydrogel electrolyte with perfect antifreezing performance is supposed to broaden the range of working temperature and practical applications of the zinc ion battery.

Reversible and homogenous zinc deposition enabled by in-situ grown Cu particles on expanded graphite for dendrite-free and flexible zinc metal anodes

The rapid development of wearable electronics has boosted the exploration of flexible and safe energy storage devices, such as zinc ion batteries or capacitors; and suppressing the dendrite growth for Zn anode is essential for enhancing their performance. Addressing this, we report a dendrite-free and flexible Zn metal anode (Zn@Cu-Ps/EG) that is based on expanded graphite (EG) decorated with in-situ formed copper particles (Cu-Ps). In this material, the Cu-Ps act as zincophilic seeds that reduce zinc nucleation overpotential, while the EG substrate induces epitaxial electrodeposition of zinc for suppressing dendrite growth. Moreover, the Cu-Ps nail the graphite nanosheets tightly and enhance the mechanical strength and flexibility of the Cu-Ps/EG composite. Consequently, the Zn@Cu-Ps/EG anode exhibits a low Zn deposition overpotential of 142.8 mV and superior cycling performance over 3000 h upon cycling at 10.0 mA cm−2 and 10.0 mAh cm−2. A flexible Zn-ion capacitor equipped with this anode delivers excellent cycling performance for over 1600 cycles at 1.0 A g−1 and stable power output at various bending statuses. This work provides a new approach for designing advanced flexible and dendrite-free Zn metal anodes for energy storage applications.

Sorbitol-modified cellulose hydrogel electrolyte derived from wheat straws towards high-performance environmentally adaptive flexible zinc-ion batteries

Thanks to low manufacturing cost, high safety level, and competitive energy density, flexible aqueous zinc-ion batteries (AZIBs) are very promising for the emerging wearable electronics. However, AZIBs suffer from low zinc stripping/plating reversibility and poor tolerance to sub-zero temperatures. Herein, food-grade sorbitol with abundant hydroxyl groups and longer molecular chain than common cryoprotectants is used to modify cellulose hydrogel electrolyte derived from wheat straws. And concentrated ZnCl2 is utilized in this hydrogel electrolyte to realize “water-in-salt” effect. The obtained hydrogel electrolyte owns superior mechanical properties, strong adhesion, high transparency, good moldability, rich porosity, ultralow freezing point (−101.5 ℃), and large ionic conductivity (35.4 and 19.7 mS cm−1 at 20 and − 40 °C, respectively). Benefiting from excellent anti-freezing ability, tuned solvation sheath, and facilitated desolvation process within this hydrogel electrolyte, high zinc stripping/plating reversibility can be achieved from 20 to − 40 °C. And the assembled flexible Zn–polyaniline (PANI) battery delivers superior electrochemical performances even under extreme conditions. This work offers new opportunities for the development of environmentally adaptive batteries and the efficient utilization of crop straws.

Borax-crosslinked hydrogel electrolyte membranes for quasi-solid state aqueous energy storage devices

A novel borax-crosslinked hydrogel electrolyte membrane is synthesized using radical polymerization to achieve superior electrochemical performances and outstanding mechanical properties. The as-synthesized electrolyte membrane displays high ionic conductivity (1.72 × 10−2 S cm−1), wide electrochemical stable window (∼2.21 V), large fracture stress (42.17 kPa) and fracture strain (205.10%). The membrane enables highly uniform Zn plating/stripping with lower overpotential and longer lifespan from the symmetric Zn cells compared with that using the liquid electrolyte. To demonstrate the applicability of the electrolyte membrane, they are used in quasi-solid state Zn metal batteries (Zn||MnO2) and Zn-ion hybrid supercapacitors (Zn||AC), respectively. The resultant Zn||MnO2 cell delivers a high discharge specific capacity retention of 95% after 1000 cycles at 0.5 A g−1, and the Zn||AC supercapacitor exhibits satisfactory specific capacitance of 290 F g−1 at 1.0 A g−1 and good rate performance. Furthermore, the flexible Zn||MnO2 and Zn||AC devices are also assembled, which can still work even at the bent and compressed states. This work provides a promising route to design the hydrogel electrolytes for the quasi-solid state aqueous energy storage devices.

Engineering iron-group bimetallic nanotubes as efficient bifunctional oxygen electrocatalysts for flexible Zn–air batteries

Air cathode performance is essential for rechargeable zinc–air batteries (ZABs). In this study, we develop a self-templated synthesis technique for fabricating bimetallic alloys (FeNi3), bimetallic nitrides (FeNi3N) and heterostructured FeNi3/FeNi3N hollow nanotubes. Owing to its structural and compositional advantages, FeNi3/FeNi3N exhibits remarkable bifunctional oxygen electrocatalytic performance with an extremely small potential gap of 0.68 ​V between the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Theoretical calculations reveal reduced Gibbs free energy for the rate-limiting O–O bond formation during OER due to the self-adaptive surface reconfiguration, which induces a synergistic effect between Fe(Ni)OOH developed in situ on the surface and the inner FeNi3/FeNi3N. ZAB fabricated using the FeNi3/FeNi3N catalyst shows high power density, small charge/discharge voltage gap and excellent cycling stability. In addition to its excellent battery performance, the corresponding quasi-solid-state ZAB shows robust flexibility and integrability. The synthesis method is extended to prepare a CoFe/CoFeN oxygen electrocatalyst, demonstrating its applicability to other iron-group elements.

A Kinetically Superior Rechargeable Zinc-Air Battery Derived from Efficient Electroseparation of Zinc, Lead, and Copper in Concentrated Solutions.

Zinc electrodeposition is currently a hot topic because of its widespread use in rechargeable zinc‐air batteries. However, Zn deposition has received little attention in organic solvents with much higher ionic conductivity and current efficiency. In this study, a Zn‐betaine complex is synthesized by using ZnO and betainium bis[(trifluoromethyl)sulfonyl]imide and its electrochemical behavior for six organic solvents and electrodeposited morphology are studied. Acetonitrile allowed dendrite‐free Zn electrodeposition at room temperature with current efficiencies of up to 86 %. From acetonitrile solutions in which Zn, Pb, and Cu complexes are dissolved in high concentrations, Zn and Pb/Cu are efficiently separated electrolytically under potentiostatic control, allowing the purification of solutions prepared directly from natural ores. Additionally, a highly flexible Zn anode with excellent kinetics is obtained by using a carbon fabric substrate. A rechargeable zinc‐air battery with these electrodes shows an open‐circuit voltage of 1.63 V, is stable for at least 75 cycles at 0.5 mA cm−2 or 33 cycles at 20 mA cm−2, and allows intermediate cycling at 100 mA cm−2.

Construction of Mixed Ionic-Electronic Conducting Scaffolds in Zn Powder: A Scalable Route to Dendrite-Free and Flexible Zn Anodes.

Zn powder (Zn-P)-based anodes are considered ideal candidates for Zn-based batteries because they enable a positive synergistic integration of safety and energy density. However, Zn-P-based anodes still experience easy corrosion, uncontrolled dendrite growth, and poor mechanical strength, which restrict their further application. Herein, a mixed ionic-electronic conducting scaffold is introduced into Zn-P to successfully fabricate anti-corrosive, flexible, and dendrite-free Zn anodes using a scalable tape-casting strategy. The as-established scaffold is characterized by robust flexibility, facile scale-up synthesis methodology, and exceptional anti-corrosive characteristics, and it can effectively homogenize the Zn2+ flux during Zn plating/stripping, thus allowing stable Zn cycling. Benefiting from these comprehensive attributes, the as-prepared Zn-P-based anode provides superior electrochemical performance, including long-life cycling stability and high rate capability in practical coin and flexible pouch cells; thus, it holds great potential for developing advanced Zn-ion batteries. The findings of this study provide insights for a promising scalable pathway to fabricate highly efficient and reliable Zn-based anodes and will aid in the realization of advanced flexible energy-storage devices.

Application value of a new Zn(II)-coordination polymer in enteral nutrition rehabilitation by enhancing intestinal villi transport function

In the present study, a novel coordination polymer (CP) based on Zn(II), that is [Zn3(H3TTHA)(μ3-O)(μ3-OH)(μ2-H2O)2(H2O)]·2H2O (1), has been generated in success with a reaction between 1,3,5-triazine-2,4,6-triamine hexaacetic acid (H3TTHA), flexible triazine polycarboxylic acid ligand and Zn(NO3)2·6H2O. Its application value on the enteral nutrition rehabilitation was assessed and the specific mechanism was also analyzed. Firstly, the recombinant Sodium/Glucose Cotransporter 1 (SGLT1) and Glucose Carrier Protein SGLT1 relative expression on the small intestinal villi epithelial cells was determined via carrying out real time reverse transcription-polymerase chain reaction (RT-PCR). In addition to this, the recovery of gastrointestinal function was determined after compound treatment.

Zn–Co-MOF on solution-free CuO nanowires for flexible hybrid energy storage devices

Pouch-type supercapacitor was developed by employing flexible Zn–Co-metal organic framework (MOF)@CuO and porous reduced graphene oxide as active electrodes. The flexible Zn–Co-MOF@CuO was fabricated by a facile two-step strategy. In the first step, Cu mesh was oxidized to cupric oxide (CuO) by a solution-free treatment. In the second step, Zn–Co-MOF was deposited on CuO scaffold through a solvothermal treatment. The as-prepared integrated Zn–Co-MOF@CuO exhibited excellent flexibility at different bending angles. The flexible Zn–Co-MOF@CuO displayed excellent electrochemical activity during three-electrode testing due to the merits of high electrical conductivity and an existence of p-n heterojunction between CuO and Zn–Co-MOF. The as-fabricated pouch supercapacitor yielded a high energy density of 41 W h kg−1 at a current density of 1 A g−1 and an excellent cycling stability of 97% after 20,000 cycles. Structural and superior electronic properties of Zn–Co-MOF@CuO were further verified through first principles calculations based on density functional theory (DFT), which perfectly supported the experimental results. The excellent electrochemical attributes of the flexible pouch supercapacitor show immense promise for next-generation electrochemical energy storage devices.

Aqueous zinc batteries using N-containing organic cathodes with Zn2+ and H+ Co-uptake

Aqueous zinc batteries are considered as one of the most promising energy storage systems for large-scale energy storage and wearable electronics, owing to their low cost and intrinsic safety. However, developing high-performance cathode materials with environmentally friendly is still an important task. Here, we demonstrate that two N-containing organic compounds, hexamethoxy hexaazatrinaphthylene (HMHATN) and hexaazatrinaphthylene (HATN), used as cathodes can exhibit high capacity with fast kinetics. Thus, the Zn//HMHATN and Zn//HATN full batteries display the high energy density of 160 and 221.6 W h Kg−1, respectively, and long-term cycling stability. Electrochemical analysis, density functional theory calculation and ex situ analysis identify that the organic cathodes involve uptake and removal of Zn2+ and H+ in the discharging-charging process. Furthermore, the flexible aqueous Zn//HMHATN and Zn//HATN batteries fabricated also have high capacity, long-term cycling life and impressive energy density, displaying its application prospect in wearable electronics.