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Traditional energy resource, i.e. coal, is converted to value-added electrode materials in electrochemical energy conversion systems. [Display omitted] • Traditional coal energy resource is converted to value-added electrode material for electrochemical energy conversion system. • The intrinsic N- and S-heteroatoms in coal effectively enhance the ORR performance. • The electrode exhibited excellent performance in Zn-air batteries with both liquid and solid electrolytes. Coal-based oxygen electrocatalysts hold immense promise for cost-effective applications in rechargeable Zn-air batteries (ZABs) and the value-added, clean utilization of traditional coal resources. Herein, an electrospun membrane electrode comprising coal-derived carbon nanosheets and directly grown carbon nanotubes (CNS/CMF@CNT) was successfully synthesized. The hierarchical porous structure of the electrode, composed of multiple components, significantly facilitates mass and ion transportation, resulting in exceptional electrochemical performance. Employing Fe as the catalyst for CNT growth, the CNS/CMF@CNT electrode exhibits a remarkable onset potential of 0.96 V and a half-wave potential of 0.87 V in the oxygen reduction reaction (ORR). In-situ surface-enhanced Raman spectroscopy reveals that hydroxyl radical desorption on the surface of CNS/CMF@CNT(Fe) is the rate-determining step of the ORR. Notably, the aqueous ZAB featuring the CNS/CMF@CNT(Fe) electrode achieved a peak power density of 216.0 mW cm−2 at a current density of 414 mA cm−2 and maintained a voltage efficiency of 65.1 % after 2000 charge/discharge cycles at 5 mA cm−2. Furthermore, the all-solid-state ZAB incorporating this electrode displayed an open-circuit voltage of 1.43 V, a peak power density of 70.1 mW cm−2 at a current density of 110 mA cm−2, and a voltage efficiency of 66.5 % after 150 charge/discharge cycles. The utilization of abundant coal as the raw material for electrode fabrication not only brings conceivable economic benefits in ZAB construction, but also commendably advances the effective application of traditional coal resources in a more sustainable manner. [ABSTRACT FROM AUTHOR]

A biomass-derived "zincophilic-hydrophobic" SEI layer is constructed on the Zn anode for dendrite-free, side reaction-free, and fast Zn electrodeposition. [Display omitted] Aqueous zinc ion batteries (AZIBs) face significant challenges stemming from Zn dendrite growth and water-contact attack, primarily due to the lack of a well-designed solid electrolyte interphase (SEI) to safeguard the Zn anode. Herein, we report a bio-mass derived polymer of chitin on Zn anode (Zn@chitin) as a novel and robust artificial SEI layer to boost the Zn anode rechargeability. The polymeric chitin SEI layer features both zincophilic and hydrophobic characteristics to target the suppressed dendritic Zn formation as well as the water-induced side reactions, thus harvesting a dendrite-free and corrosion-resistant Zn anode. More importantly, this polymeric interphase layer is strong and flexible accommodating the volume changes during repeated cycling. Based on these benefits, the Zn@chitin anode demonstrates prolonged cycling performance surpassing 1300 h under an ultra-large current density of 20 mA cm−2, and a long cycle life of 680 h with a record-high zinc utilization rate of 80 %. Besides, the assembled Zn@chitin/V 2 O 5 full batteries reveal excellent capacity retention and rate performance under practical conditions, proving the reliability of our proposed strategy for industrial AZIBs. Our research offers valuable insights for constructing high-performance AZIBs, and simultaneously realizes the high-efficient use of cheap biomass from a "waste-to-wealth" concept. [ABSTRACT FROM AUTHOR]

[Display omitted] • A scalable method is developed to fabricate free-standing and integrated electrodes. • The synergistic effect within the electrode enables a series of superior properties. • The developed electrode offers significantly improved electrochemical performance. • Commercial level of areal capacity can be readily achieved with ultralow N/P ratio. • The electrode owns impressive tolerance to low temperatures and bending deformations. Aqueous zinc-ion batteries (AZIBs) present a highly promising avenue for the deployment of grid-scale energy storage systems. However, the electrodes fabricated through conventional methodologies not only suffer from insufficient mass loadings, but also are susceptible to exfoliation under deformations. Herein, a scalable and cost-effective freezing-thawing method is developed to construct free-standing and integrated electrode, comprising H 11 Al 2 V 6 O 23.2 , carboxymethyl cellulose, and carbon nanotubes. Benefiting from the synergistic effect of these components, the resultant electrode exhibits superior flexibility and robustness, large tensile strength, exceptional electrical conductivity, and favorable electrolyte wettability. Under a large mass loading of 8 mg cm−2 (corresponding to a negative/positive electrode capacity ratio of 2.09), the electrode achieves remarkable capacity of 345.2 mAh/g (2.76 mAh cm−2) at 0.2 A/g and maintains 235.2 mAh/g (1.88 mAh cm−2) at 4 A/g, while sustaining an impressive capacity retention of 97.7 % over 5000 cycles. These considerably outperform conventional electrodes employing traditional binders. Even at an elevated mass loading of 14 mg cm−2 or when operated at a low temperature of − 30 °C, the electrode continues to deliver excellent electrochemical performance (e.g. , extraordinary areal capacity of 4.32 mAh cm−2). In addition, the electrode owns outstanding tolerance to external forces. This research contributes to our understanding of the pivotal challenges within the realm of AZIB technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • An operando crystal-amorphous transformation of VOOH is demonstrated via in-situ / ex-situ structural analyses. • The unique crystal-amorphous transformation allows the obtained amorphous V 2 O 5 to achieve the high capacity, superior rate performance, and high energy and power densities. • The potentiality of cathode materials via operando crystal-amorphous transformation to achieve the enhanced zinc storage is confirmed. Aqueous zinc-ion batteries have obtained broad attention due to their high safety, eco-friendliness, and low cost. However, they are still in the developing stage considering the limited candidate of high-performance cathode materials. Furthermore, the intrinsic storage zinc mechanism is also needed to uncover. Here, we propose an operando crystal-amorphous transformation of tunnel-type VOOH and the obtained amorphous V 2 O 5 serves as a high-performance zinc-ion battery cathode. In-situ X-ray diffraction corroborates the unique operando crystal-amorphous transformation of VOOH during the initial charging process. X-ray photoelectron spectroscopy and transmission electron microscopy further demonstrate the element valence evolution and the lattice structure change, respectively. The operando electrochemical crystal-amorphous transformation allows the obtained amorphous V 2 O 5 to achieve the high capacity of ∼ 350.7 mAh g−1, rate performance (151.2 mAh g−1 at 6.4 A g−1), energy and power densities (137 Wh kg−1 at 6831 W kg−1), unveiling a promising approach of cathode materials via operando crystal-amorphous transformation to achieve the enhanced zinc storage. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile "chemical blowing" strategy is developed to expand the dense and micron-scale thickness walls into interconnected carbon nanosheets. • Zn(NO 3) 2 is proved to functioned as blowing agent, precursor of template, activator, and nitrogen dopant. • The optimized thick carbon monolith with high-mass loading (∼30 mg cm−2) delivers encouraging capacitive performance in low-temperature. Biomass-derived carbon materials are promising electrode materials for capacitive energy storage. Herein, inspired by the hierarchical structure of natural wood, carbon monoliths built up by interconnected porous carbon nanosheets with enriched vertical channels were obtained via zinc nitrate (Zn(NO 3) 2)-assisted synthesis and served as thick electrodes for capacitive energy storage. Zn(NO 3) 2 is proved to function as expansion agent, activator, dopant, and precursor of the template. The dense and micron-scale thickness walls of wood were expanded by Zn(NO 3) 2 into porous and interconnected nanosheets. The pore volume and specific surface area were increased by more than 430 %. The initial specific capacitance and rate performance of the optimized carbon monolith was approximately three times that of the pristine dense carbon framework. The assembled symmetric supercapacitor possessed a high initial specific capacitance of 4564 mF cm−2 (0–1.7 V) at −40 °C. Impressively, the robust device could be cycled more than 100,000 times with little capacitance attenuation. The assembled zinc-ion hybrid capacitor (0.2–2 V) delivered a large specific capacitance of 4500 mF cm−2 at −40 °C, approximately 74 % of its specific capacitance at 25 °C. Our research paves a new avenue to design thick carbon electrodes with high capacitive performance by multifunctional Zn(NO 3) 2 for low-temperature applications. [ABSTRACT FROM AUTHOR]

[Display omitted] As an important potential candidate for large-scale energy storage, rechargeable zinc metal batteries have become a research hotspot. Zn metal anodes are an extremely crucial component of rechargeable Zn metal batteries. However, the Zn dendrites, the evolution of hydrogen and side reactions on the surface of the Zn metal anodes severely hinder its commercial use. Here, we report a modified Zn metal anode with a layer of nitrogen-defective graphitic carbon nitride (NDCN) nanosheets coated onto a commercial Zn foil by a simple spraying method. The NDCN coating on the anode's surface not only provides zincophilic sites, but also drives the deposition of zinc with a particular crystallographic orientation. At the same time, the formation of zinc dendrites and the evolution of hydrogen were suppressed, which enhanced the reversibility of the anode. Thus, the symmetric cells with the NDCN-protected zinc foil (NDCN@Zn) electrodes remained stable for 2000 h at a current density of 5 mA cm−2. More importantly, the long-term cycling performance of the full cell tested at 1 A g−1 retained approximately 88 % of its capacity even after 2300 cycles. This simple but effective method will provide a reference for future studies on protecting the anodes of zinc metal batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Aqueous zinc ion batteries (AZIBs) are receiving broad attention owing to their high safety and low cost. However, the high mechanical strength and irreversible growth of zinc dendrites limit the practical application of AZIBs. Herein, regular mesh-like gullies are built on the surface of zinc foil (M150 Zn) by using simple model pressing method and stainless steel mesh as a mold. Due to the charge-enrichment effect, zinc ion deposition and stripping will be preferentially carried out in the grooves to keep the outer surface flat. In addition, zinc is exposed to 002 crystal surface in the gully after being pressed, and the deposited zinc is more inclined to grow at a small angle, so that it has a sedimentary morphology parallel to the basement. Consequently, at a current density of 0.5 mA cm−2, the M150 zinc anode has a voltage hysteresis of only 35 mV and a cycle life of up to 400 h (relative to a zinc foil of 96 mV and 160 h). Even more imposing is that the full cell has a capacity retention of approximately 100% after 1000 cycles at 2 A g−1 and a specific capacity of almost 60 mAh g−1 when activated carbon is used as the cathode. It is a promising method to improve the stable cycle performance of AZIBs by using a simple method to realize the non-prominent dendrites on the surface of zinc electrode. [ABSTRACT FROM AUTHOR]

The 1,3,6-Hexanetricarbonitrile (HTCN) as an efficient additive to Zn(OTF) 2 electrolyte is favorable for the quick Zn2+ transportation, as well as the formation of strong and stable SEI film to prevent the irregular growth of zinc dendrites and the electrode corrosion from the electrolyte. [Display omitted] The growth of Zn dendrites and parasitic side reactions between electrode and electrolyte are major obstacles to the development of rechargeable aqueous zinc-ion batteries. To address these critical issues, the use of nitrile organic compounds as electrolyte additives holds great promise. Herein, for the first time, we prepared a small volume concentration (x) of 1,3,6-Hexanetricarbonitrile (HTCN- x) as additives into zinc trifluoromethanesulphonate (Zn(OTF) 2) electrolyte and studied their electrochemical properties in Zn || Zn x V 2 O 5 ·nH 2 O (Zn || ZVO) cells. It was found that the strong interaction between H 2 O and HTCN could significantly reduce the population of solvated H 2 O outside the solvation sheath, leading to reduced side reactions in the aqueous Zn(OTF) 2 electrolyte. Moreover, the HTCN additive also facilitates the formation of strong and stable solid electrolyte interphase (SEI) film on the surface of the Zn anode, which effectively prevents the growth of Zn dendrites and the anode corrosion caused by the electrolyte. As a result, the HTCN- x (x = 0.3) electrolyte enabled the symmetrical Zn || Zn cell to cycle over 950 h at a current of 1 mA cm−2 with a limited capacity of 1 mAh cm−2. When the HTCN-0.3 electrolyte was used in Zn || ZVO cell, the cell delivered a high initial capacity of 355.6 mAh g−1 at 0.1 A g−1 and maintained a high capacity of 330.0 mAh g−1 at 1 A g−1 after 465 cycles. [ABSTRACT FROM AUTHOR]

The well-regulated Co-doping Ni(OH) 2 @NF charge mediator was designed and developed for highly-efficient two-step decoupled hydrogen/oxygen evolution. [Display omitted] • Well-regulated Co-doping Ni(OH) 2 @NF electrode as a charge mediator. • Highly-efficient two-step decoupled hydrogen/oxygen evolution. • Electrochemical decoupled hydrogen evolution without external energy supply. The realization of the membrane-free two-step water electrolysis is particularly important yet challenging for the low-cost and large-scale supply of hydrogen energy. In this effort, Co-doped Ni(OH) 2 nanosheets were successfully anchored onto the nickel foam (NF) substrate through the in-situ growth of metal-organic frame material and the subsequent alkali-etching technique. Using the well-regulated Co-doping Ni(OH) 2 @NF electrodes as a charge mediator, electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were decoupled on time scales, thus affording a membrane-free two-step route for H 2 and O 2 productions. In this architecture, the first HER process on the cathode could be maintained for 1300 s at a current of 100 mA, while the corresponding Ni(OH) 2 charge mediator was simultaneously oxidized to NiOOH, with a decent cell voltage of 1.542 V. The subsequent OER process involved a reduction/regeneration of Ni(OH) 2 (from NiOOH to Ni(OH) 2) and an anodic O 2 -production, with an operating voltage of 0.291 V. Moreover, the Ni-Zn battery assembled through the combination of NiOOH and Zn sheet could replace the second step of OER to achieve the coupling of continuous H 2 -production and battery discharge, thus also providing a new way for hydrogen production without an external power supply. Experiment and theoretical calculations have shown that the cobalt-doping not only improved the conductivity of the charge-buffer electrode, but also shifted its redox potential cathodically and boosted the adsorption affinity of the buffer medium to OH– ions, both contributing to promoted HER and OER activity. Therefore, this decoupled water electrolysis device affords a promising pathway to support the efficient conversion of renewables to hydrogen. [ABSTRACT FROM AUTHOR]

[Display omitted] ZnIn 2 S 4 (ZIS) is one of the widely studied photocatalyst for photocatalytic hydrogen evolution applications due to its prominent visible light response and strong reduction ability. However, its photocatalytic glycerol reforming performance for hydrogen evolution has never been reported. Herein, the visible light driven BiOCl@ZnIn 2 S 4 (BiOCl@ZIS) composite was synthesized by growth of ZIS nanosheets on a template-like hydrothermally pre-prepared wide-band-gap BiOCl microplates using simple oil-bath method to be used for the first time for photocatalytic glycerol reforming for photocatalytic hydrogen evolution (PHE) under visible light irradiation (λ > 420 nm). The optimum amount of BiOCl microplates in the composite was found 4 wt% (4% BiOCl@ZIS) in the presence of in-situ 1 wt% Pt deposition. Then, the in-situ Pt photodeposition optimization studies over 4% BiOCl@ZIS composite showed the highest PHE rate of 674 μmol g-1h−1 with the ultra-low platinum amount (0.0625 wt%). The possible mechanisms behind this improvement can be ascribed to the formation of Bi 2 S 3 low-band-gap semiconductor during BiOCl@ZIS composite synthesis resulting in Z-scheme charge transfer mechanism between ZIS and Bi 2 S 3 upon visible light irradiation. This work expresses not only the photocatalytic glycerol reforming over ZIS photocatalyst but also a solid proof of the contribution of wide-band-gap BiOCl photocatalysts to enhancement of ZIS PHE performance under visible light. [ABSTRACT FROM AUTHOR]

Multicomponent catalysts Co/BN-CNT/VN were synthesized using Co-modified boron-rich POMs as the precursor. The Co/BN-CNT/VN assembled Zn-air battery exhibit a high power density of 156.3 mW cm−2 and an ultrastable cycling capability of up to 1000 cycles. [Display omitted] • Multicomponent catalysts Co/BN-CNT/VN were successfully synthesized using Co-modified boron-rich POMs as the precursor. • The concept of superior bifunctional Co/BN-CNT/VN catalytic sites for oxygen reduction reactions and oxygen evolution reactions was experimentally validated. • The assembled Zn-air battery exhibit a high power density of 156.3 mW cm−2 and an ultrastable cycling capability of up to 1000 cycles. Rational design of high-performance bifunctional electrocatalysts to accelerate the sluggish oxygen reduction reactions (ORR) and oxygen evolution reactions (OER) in rechargeable Zn–air batteries remain an enduring challenge. The construction of multicomponent catalysts is a promising solution to achieve this goal. Herein, B and N co-doped interconnecting graphite carbon and carbon nanotube with the decoration of Co and vanadium nitride (VN) nanoparticles (Co/BN-CNT/VN) are synthesized using Co-modified polyoxovanadoborates as precursors. The optimized composite achieves superior bifunctional oxygen electrocatalytic activity and stability, which is comparable to noble metal catalysts and reported bifunctional electrocatalysts. Specifically, the half-potential of ORR reaches 0.85 V, and the overpotential of OER is low to 296 mV at a current density of 10 mA cm−2. Strikingly, zinc–air batteries assembled based on Co/BN-CNT/VN demonstrate a small charge–discharge voltage gap of 0.873 V, a remarkable peak-power density of 156.3 mW cm−2, and outstanding cycling durability (∼1000 cycles at 10 mA cm−2). This work affords a new alternative strategy to create cost-effective and high-potency bifunctional oxygen electrocatalysts for advanced air batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Flexible aqueous zinc-ion batteries (AZIBs) require high conductive and adhesive hydrogel electrolytes. However, high adhesion tends to hinder ion conduction rate. Herein, we designed a water/glycerol binary solvent coordinating the hydrophilic polymers to reconstruct the water molecules' environment in the hydrogel. As a consequence, the interface adhesion strength between Zn and the hydrogel reached 3.0 kPa and the ionic conductivity was up to 16.8 mS cm−1. In addition, inspired by the slurry electrode preparation method, we developed a simple blade coating technique using a non-Newtonian polysaccharide liquid solution to construct an ultra-thin hydrogel electrolyte in situ on the cathode. The thickness of the obtained hydrogel reached 70 μm, and the ultrathin flexible AZIBs were easily constructed by pasting a Zn anode directly on the adhesive hydrogel, showing the potential of flexible AZIBs scalable assembly. In addition, the Zn//Zn symmetrical cells with the hydrogel electrolyte provided stable cycling performance for over 400 h at 0.1 mA cm−2 with suppressed dendrite growth. The assembled Zn//Polyaniline battery and Zn//V 2 O 5 battery also exhibited excellent capacity retention after cycles. This work has realized the hydrogel electrolyte with high adhesion and conductivity, which has good adaptability to metal electrodes and opened up a new practical way for large-scale assembly of flexible energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] Na 5 V 12 O 32 (NVO) is a potential cathode for aqueous zinc ion batteries (AZIBs). However, it suffers severe capacity decay due to the dissolution of the active material. The structural design may be an effective solution to the problem. Herein, we construct a typical two-dimensional hierarchical structure of Na 5 V 12 O 32 @graphene (NVO@G) via a facile molten salt method. The capacity fading problem is solved by the in-situ conversion of NVO@G to a more stable hierarchical system during cycling. The in-situ formed zinc pyrovanadate (Zn 3 V 2 O 7 (OH) 2 ·2H 2 O, ZVO) nanosheets on the surface of graphene exhibits excellent zinc-ion storage stability. The presence of graphene induces the growth of NVO nanobelts to construct the typical two-dimensional hierarchical structure. Additionally, the in-situ conversion makes the formed ZVO nanosheets contact with graphene better. Benefitting from the hierarchical nanostructure and in-situ phase conversion, the NVO@G electrode shows excellent long-term stability (96.4% retention after 340 cycles at 0.3 A g−1, 85.7% retention after 4400 cycles at 5 A g−1) and high zinc ion storage capacity (220 mAh g−1 at 0.3 A g−1), which is superior to those of most electrode materials previously reported. [ABSTRACT FROM AUTHOR]

A CeO 2 /MnO x @C hollow cathode derived from the self-assembly of Ce-Mn-MOFs was synthesized, which could possess high reversible capacity and excellent cycling stability for aqueous zinc-ion batteries. [Display omitted] The construction of composite materials is an effective strategy to solve the problems of poor conductivity, manganese dissolution, and volume expansion of manganese-based materials. Herein, a CeO 2 /MnO x @C hollow composite cathode derived from the self-assembly of Ce-Mn-metal-organic frameworks (Ce-Mn-MOFs) was synthesized. The abundant oxygen vacancies and good electronic/ionic conductivity of CeO 2 improve the electrical conductivity of composite, enhancing the rate performance. The unique hollow structure could inhibit manganese dissolution and alleviate volume expansion. The results indicate that the 1 % CeO 2 /MnO x @C composite cathode possesses a high reversible capacity and excellent cycling stability. Specifically, the 1 % CeO 2 /MnO x @C composite cathode shows a remarkable reversible specific capacity of 130 mAh/g at a current density of 500 mA g−1, 6.5 times more than the pure MnO x (20 mAh/g). The capacity retention is up to 99.5 % relative to the initial capacity after 800 cycles. This study provides a new strategy for designing rare-earth composite electrodes to improve electrochemical performance. [ABSTRACT FROM AUTHOR]

The absorbed gelatin molecules impede the H 2 O reaching Zn surface by desolvation to enhance the anticorrosion behavior, and adjust the local pH value based on their –CN 3 H 4 and –COOH to stabilize the electrode/electrolyte interphase and reduce dendrite growth sites. Because the gelatin molecule is too large to enter the defect, and the gelatin molecule is adsorbed on the outside of the defect, which has strong confined effect on the Zn2+, "electrostatic shield" formed from positively charged –CN 3 H 5 + in the mild acid condition suppress 2D diffusion and accumulation of Zn2+, guiding Zn ions to repair the damaged electrode surface. [Display omitted] • Two stages of dendrite growth were analyzed: the formation of initial sites and the 2D growth of dendrites. • The amphiphilic macromolecules adsorbed on the electrode sheet can isolate the water to avoid the corrosion of zinc. • Amphiphilic macromolecules can act as buffers to adjust pH for the stability of the electrode/electrolyte interface. • The molecule regulates zinc to continuously fill the defect during the electrochemical cycle to complete the self-healing. The reversibility and stability of aqueous zinc-ion batteries are largely limited by inevitable parasitic reactions at the interface and uncontrollable dendrite growth. Inspired by self-healing smart electronic materials, we propose a confinement strategy with gelatin, an amphiphilic macromolecule, as additive to regulate the deposition behavior of Zn ions and utilize the dendrites to fill the surface defects formed by inevitable interfacial parasitic reactions. Absorbed gelatin molecules impede H 2 O reaching Zn electrode surface to enhance the anticorrosion behavior and adjust the local pH value, which is a "smart" way to stabilize the electrode/electrolyte interphase. Additionally, the confined effect of absorbed gelatin molecules on Zn2+ and "electrostatic shield" formed from positive charged –CN 3 H 5 + suppress 2D diffusion and accumulation of Zn2+, guiding Zn continuously depositing inside the defect during electrochemical cycling, then self-healing of electrode surface defects is achieved. Under the synergetic effects of these merits, Zn electrode demonstrates almost unchangeable surface after soaking in the electrolyte for 10 days, and stably cycle more than 1100 h at 0.5 mA cm−2 and 1300 h at 3.0 mA cm−2 in symmetric cell. In addition, the full batteries using the base electrolyte with 0.5 and 1.0 g/L gelatin can stably cycle for 3000 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZIF-8-derived N -doped porous carbon wrapped in porous carbon films is prepared. • The obtained N -PC@CF exhibits the excellent ORR performance and stability. • The battery performances of N -PC@CF are equivalent to that of commercial Pt/C. • The excellent ZAB performance is due to the coupling of double-layer porous carbon. Metal-organic frameworks are a new type of catalyst precursor with high specific surface area and controllable composition, which can be modified by post-treatment and are suitable for use as cathode catalysts for Zn-air batteries (ZABs). Here, a self-doped nitrogen nanocatalyst (N -PC@CF) with a double-layered porous structure is rationally designed for flexible solid-state ZABs. The outer porous carbon shell of the N -PC@CF is highly hydrophilic and O 2 permeable, while the layered porous structure exposes sufficient active sites to shorten the mass transfer distance, which would promote electrocatalytic performance and increase flexibility efficiently. The obtained N -PC@CF has an onset potential of 0.926 V and a half-wave potential of 0.843 V in the oxygen reduction reaction test, which is equivalent to commercial Pt/C. Most importantly, the maximum power density of the assembled ZAB is 134.7 mW cm−2 and it exhibits a specific capacity of 776.8 mA h g−1 at 10 mA cm−2, which is better than the 99.9 mW cm−2 of the Pt/C-based battery. An obvious improvement in the constant current discharge–charge cycle durability of the ZAB is found when compared with Pt/C. The specific capacities of ZAB with N -PC@CF as the air cathode at 5, 10 and 15 mA cm−2 are 842.7, 776.8 and 715.0 mAh g−1 (calculated by the mass of zinc consumed), respectively, corresponding to high energy densities of 1089.7, 977.3 and 842.2 Wh kg−1. A flexible solid-state battery is assembled with excellent flexibility and stability, even if the battery is folded into a large angle (160°). This work provides a new strategy for the design and synthesis of metal-free air cathodes. [ABSTRACT FROM AUTHOR]

The hierarchical nickel oxalate (Ni-OA) superstructure composed of 1D nanorods was synthesized by a solution precipitation method and applied to aqueous Ni-Zn batteries. [Display omitted] Hierarchical superstructures in nano/microsize can provide improved transport of ions, large surface area, and highly robust structure for electrochemical applications. Herein, a facile solution precipitation method is presented for synthesizing a hierarchical nickel oxalate (Ni-OA) superstructure composed of 1D nanorods under the control of mixed solvent and surfactant of sodium dodecyl sulfate (SDS). The growth process of the hierarchical Ni-OA superstructure was studied and indicated that the product had good stability in mixed solvent. Owing to smaller size, shorter pathway of ion diffusion, and abundant interfacial contact with electrolytes, hierarchical Ni-OA superstructure (Ni-OA-3) showed higher specific capacity than aggregated micro-cuboids (Ni-OA-1) and self-assembled micro/nanorods (Ni-OA-2). Moreover, the assembled Ni-OA-3//Zn battery showed good cyclic stability in aqueous electrolytes, and achieved a maximum energy density of 0.42 mWh cm−2 (138.75 Wh kg−1), and a peak power density of 5.36 mW cm−2 (1.79 kW kg−1). This work may provide a new idea for the investigation of hierarchical nickel oxalate-based materials for electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Cationic surfactant type additive TMA 2 SO 4 is used to suppress zinc dendrites and improve the life time of zinc ion batteries. [Display omitted] Recently, zinc metal has been considered as a promising metal anode for aqueous rechargeable metal ion batteries due to its low electrochemical potential and high theoretical capacity. However, zinc metal suffers from hydrogen evolution reaction (HER) and dendrite growth during plating/stripping. Here, we propose a low-cost, effective and non-toxic electrolyte additive, tetramethylammonium sulfate hydrate (TMA 2 SO 4), as a simple cationic surfactant additive for zinc-ion batteries, to trigger the smooth Zn deposition during charging and discharging process. It is found that TMA 2 SO 4 enable the realization of the deposition of Zn ions along the surface of zinc foil laterally without stacking and thus dendrite growth and side reactions are greatly mitigated by the electrolyte additive of TMA 2 SO 4 even when the amount of the additive is as low as 0.25 mM. As a result, the TMA 2 SO 4 additive induces excellent cycling stability over 1800 h at the current density of 0.5 mA cm−2 with the limited capacity of 0.5 mAh cm−2 for the Zn-Zn symmetrical cell. Moreover, the electrolyte with TMA 2 SO 4 can well match with MnO 2 cathode, which achieves the high initial capacity of 181.3 mAh g−1 at 0.2 A g−1 and long-term cycling stability with the capacity retention of 98.72 % after 200 cycles for the Zn/MnO 2 full cell. This work provides a general electrolyte design strategy to suppress zinc dendrite growth and side reactions to achieve long-lifespan zinc metal anodes for aqueous zinc ion batteries by electrostatic shielding effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • FeNi-NCNT was prepared by carbonizing Ni2+/Zn2+-PAT-[Fe(CN) 6 ]3− complex precursor. • FeNi-NCNT offered high ORR/OER activities with E 1/2 = 0.835 V and E j = 10 = 1.560 V. • FeNi-NCNT-based aqueous RZAB showed ultralong cycle life (400 h at 25 mA cm−2). • FeNi-NCNT-based solid RZAB exhibited excellent stability and flexibility. In this work, we present an efficient bifunctional electrocatalyst comprising iron-nickel (FeNi) alloy nanoparticles confined in nitrogen-doped carbon nanotubes (denoted FeNi-NCNT) for zinc-air batteries. The FeNi-NCNT electrocatalyst is fabricated by anion-exchange of nickel(II) ion/zinc(II) ion-2,4,6-tris-(di(pyridin-2-yl)amino)-1,3,5-triazine complex with ferricyanide anion followed by mixing with melamine and then carbonization. The resultant FeNi-NCNT electrocatalyst displays excellent bifunctional activity with a low reversible oxygen electrode index of 0.725 V. The rechargeable aqueous zinc-air battery fabricated with FeNi-NCNT air cathode manifests both high specific capacity (819 mAh g−1 Zn at 5.0 mA cm−2) and long cycle life (1500 cycles/1000 h at 10 mA cm−2, 600 cycles/400 h at 25 mA cm−2, and 165 cycles/110 h at 50 mA cm−2). Moreover, flexible solid-state zinc-air battery assembled with FeNi-NCNT air cathode can deliver a specific capacity of 765 mAh g−1 Zn at 5.0 mA cm−2, a power density of 84.8 mW cm−2, and a cycle life of 110 h (330 cycles) at 2.0 mA cm−2. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple method for synthesizing multifunctional N -CNTs@MOF FeCo@CC nanoarrays catalysts. • Electrode materials perform efficiently for ORR, OER, and HER in alkaline solutions. • The N -CNTs@MOF FeCo@CC nanoarrays catalyst was developed as a free-standing air-electrode for zinc-air batteries. • The zinc-air batteries exhibit outstanding battery performance and cyclic stability. The development of multicomponent materials is the most efficient and successful way for creating advanced multifunctional catalysts. Herein, the bimetal FeCo nanoarrays enclosed N -CNTs have a high surface on carbon cloth support, which promotes efficient electron transport and prevents nanoparticle aggregation. Taking advantage of the high-level use of active material and fast charge transfer, the developed electrocatalyst exhibits excellent multifunctional electrocatalyst such as oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The N -CNTs@MOF FeCo nanoarrays @CC exhibit higher activity than reference catalysts including MOF FeCo nanoarrays@CC, FeCo nanoarrays@CC, and CC. Interestingly, the synthesized multifunctional catalyst, which serves as the air electrode in zinc-air batteries with liquid electrolytes as well as solid-state gel electrolytes possesses outstanding charging-discharge performance and long service life. This study provides enormous potential for the real implementation of portable, even wearable, and efficient rechargeable batteries in the future. [ABSTRACT FROM AUTHOR]

A novel flexible electrode of 3D interconnected ultrathin MnO 2 nanosheets grown on carbon cloth coupled with Mxene was prepared and applied to zinc-ion batteries. Because Mxene is coated on the surface of MnO 2 nanosheets, the capacitance contribution and charge storage capacity are effectively improved, which makes CC@MnO 2 @Mxene composites have high specific capacity and other electrochemical properties. [Display omitted] • A novel flexible electrode of CC@MnO 2 @MXene was prepared and applied to zinc-ion batteries. • The 3D interconnected ultrathin MnO 2 nanosheets structure facilitates the penetration of electrolyte. • Mxene is coated on the surface of MnO 2 effectively improve capacitance contribution and the charge storage capacity. • CC@MnO 2 @Mxene-10//Zn quasi-solid-state flexible batteries show good application prospects in the flexible device. Aqueous zinc-ion batteries (ZIBs) are receiving a continuously increasing attention for the flexible and wearable electronics, due to their non-toxicity, non-flammability, and low-cost features. The development of high-performance flexible cathodes is of great significance to the development of flexible ZIBs. In this work, the flexible electrode of three-dimensional (3D) interconnected ultrathin MnO 2 nanosheets on carbon cloth (CC@MnO 2) coated with Ti 3 C 2 T x MXene (CC@MnO 2 @MXene) is prepared by electrodeposition and dipping methods, in which CC@MnO 2 is put into MXene dispersion for impregnation treatment to make the CC@MnO 2 fibers wrapped with MXene completely. The results show that the coating of MXene improves the conductivity of the composite, and the interface between MXene and MnO 2 provides more active sites. Therefore, CC@MnO 2 @MXene-10 electrode as the cathode of zinc ion battery provides high charge storage performance (517.0 mAh g−1 at 0.1 A g−1), excellent cycling stability (80.6 mAh g−1 after 800 cycles at 1 A g−1) and excellent energy density (701.3 Wh kg−1 at 133.8 W kg−1). Finally, flexible quasi-solid battery based on CC@MnO 2 @MXene composite as cathode was assembled, and the flexible electrodes show potential for application. [ABSTRACT FROM AUTHOR]

Sandwich-like V 2 O 5 /graphene composites with adjustable graphene content (denoted as V 2 O 5 /xG) were designed to demonstrate the effects of electrode structure and wetting characteristics on zinc storage properties. The V 2 O 5 /5G with 10.4% graphene content exhibits effective inhibition of vanadium dissolution, high capacity and excellent cycling stability. [Display omitted] Improving the stability of the layered structure and suppressing vanadium dissolution during repeated Zn2+ insertion/extraction processes are considered to be the key to promote the electrochemical stability of vanadium-based cathodes for ZIBs. In this work, a group of sandwich-like V 2 O 5 /graphene composites (V 2 O 5 /xG) were controllably fabricated by tuning the amount of hydrophobic graphene. With the increase of graphene content, the corresponding electrochemical properties show a parabolic trend that increase first and then decrease. A maximum capacity of 270 mAh g−1 after 100 cycles at 0.1 A g−1 and a superior cycle stability with 82.4% capacitance retention after 6000 cycles at 10 A g−1 are achieved when the amount of graphene is about 10.4% (that is V 2 O 5 /5G). The addition of graphene has been proven not only to act as an effective conductive network to promote charge transfer and enhance the pseudocapacitance effect on the electrode surface; but also to increase the electrode hydrophobicity, effectively inhibiting the dissolution of vanadium, and promoting the desolvation and diffusion kinetics of hydrated zinc ions. Moreover, the graphene layer, as a structural stabilizer, effectively prevents the structure of the active component V 2 O 5 from collapsing during cycling, contributing to the long-term cycle life. [ABSTRACT FROM AUTHOR]

[Display omitted] Organic materials are attracting extensive attention as promising cathodes for rechargeable aqueous zinc-ion batteries (ZIBs). However, most of them fail to implement the requirement of batteries with combined high-rate and long-cycle performance. Herein, we report a flexible organic molecule 2,3-diaminophenazine (DAP) which exhibits ultrahigh rate performance up to 500C and high capacity retention of 80% after 10,000 cycles at 100C (25.5 A g−1). Moreover, the Zn2+ storage mechanism in the DAP electrode is revealed by ex-situ characterization technologies and theoretical calculation, and the redox active centers C N participate in the reversible electrochemical reaction process. Furthermore, electrochemical analyses show that surface-controlled electrochemical behavior contributes to the high-rate performance of DAP cathodes. Besides, its excellent long-cycle performance can be ascribed to the suppressed DAP dissolubility by using a modified glass fiber separator with carbon nanotubes (CNT) film. Our work provides useful insight into the design of high-rate and long-life ZIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] The rigorous fabrication of electrode materials using upper-ranked porous precursor especially metal organic frameworks (MOFs) are challenging but appealing task to procure electrochemical energy storage and conversion system with altitudinous performance. Herein, we replenish the rational construction of atypical electrode of hollow Zn-Ni-Co-oxide (ZNCO) nanosheet arrays onto rGO garnished Ni foam (rGO/NF) via two step solution based method. Firstly, 2D Zn-Co-MOFs derived nanoleave arrays are prepared by co-precipitation method. Next, hollow and porous ZNCO nanostructure from 2D solid nanoleave arrays are achieved by ion-exchange and etching process conjoined with post annealing treatment. The as-fabricated hierarchical ZNCO nanosheet arrays offer large numbers of electroactive sites with short ion-diffusion pathways, reflecting the outstanding electrochemical performance in-terms of excellent specific capacity (267 mAh g−1) ultra-high rate capability (83.82% at 50 A/g) and long-term cycling life (~90.16%) in three electrode configuration for supercapacitor (SCs). Moreover, the hollow and porous ZNCO nanostructure responds as immensely active and substantial electrocatalyst for methanol oxidation with lowest onset potential of 0.27 V. To demonstrate the practicability, hybrid supercapacitor (HSC) device is constructed using ZNCO@rGO-NF nanostructure as positive and rGO decorated MOF derived porous carbon (rGO-MDPC) as negative electrode. The as-assembled ZNCO//rGO-MDPC ASC device delivers higher energy density of 61.25 Wh kg−1 at the power density of 750 W kg−1 with long-term cyclic stability (<6% to its initial specific capacity value) after 6000 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sodium lignosulfonate is used as the electrolyte additive of zinc-ion batteries. • The performances of Zn//MnO 2 battery are significantly improved by the additive. • The Zn//Zn cell with the modified electrolyte realizes excellent reversibility. • The Zn//Cu cell with the modified electrolyte exhibits uniform zinc striping/plating. • The additive can effectively suppress dendrite growth and byproduct formation. Thanks to high safety and low cost, rechargeable zinc-ion batteries (RZIBs) have become a promising candidate for grid-scale energy storage systems. However, zinc anodes suffer from severe dendrite growth and irreversible side reactions, leading to poor cyclability of RZIBs. In this work, low-cost sodium lignosulfonate (SL) is utilized as the electrolyte additive to solve this problem. The added amount of SL is optimized to be 0.02%, which enables the Zn//α-MnO 2 battery to deliver a large capacity of 146 mAh g−1 after 1000 cycles at 1 A g−1, corresponding to a high capacity retention of 83.5%. The Zn//Zn symmetric cell with the modified electrolyte also shows excellent cyclability even under a commercial level of areal specific capacity (4 mAh cm−2). Overall, the results of this study confirm that the SL additive can improve the ionic conductivity of electrolyte, restrict the two-dimensional planar diffusion of Zn2+ ions at the electrode/electrolyte interface, lower the nucleation overpotential of Zn2+ ions, prevent side reactions, and inhibit the corrosion of Zn metal. Therefore, the dendrite growth and byproduct formation can be effectively suppressed. This study provides new insights into protecting metal electrodes of electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

The CoC x /(Co 0.55 Fe 1.945) 2 P@C electrocatalyst developed through a phosphating strategy from covalent porphyrin polymer absorbed with Co 3 [Co(CN) 6 ] 2 and NaH 2 PO 2 precursors that displays superior electrocatalytic activity for ORR, OER and rechargeable zinc-air battery. • A phosphating strategy was developed for bimetallic phosphides modified carbon catalyst. • CoC x /(Co 0.55 Fe 1.945) 2 P@C displays improved ORR and OER bifunctional performances. • The introducing of P leading to a decreased energy gap of CoC x /(Co 0.55 Fe 1.945) 2 P@C. • Good stability and higher power density than Pt/C are revealed in zinc-air battery. It is very important, but also challenging to produce high-activity, high durability and affordable non-noble-metal-bifunctional-electrocatalysts for sustainable energy application. Here, one-pot synthesized iron covalent porphyrin polymers (FePor-CPP), with carefully placed Fe, N atoms, a regular porous structure, Co 3 [Co(CN) 6 ] 2 and NaH 2 PO 2 precursors were carbonized into N,P-doped carbon nanospheres with the active species of both bimetallic CoFe phosphides and CoC x nanoparticles (denoted as CoC x /(Co 0.55 Fe 1.945) 2 P@C). By employing the CoC x /(Co 0.55 Fe 1.945) 2 P@C as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrode catalysts, superior catalytic activity is achieved with E 1/2 of 0.84 V for ORR, and overpotential of 0.39 V at 10 mA cm−2 for OER in an alkaline medium, respectively. Furthermore, CoC x /(Co 0.55 Fe 1.945) 2 P@C as air electrode for rechargeable Zn-air battery shows power density as high as 131 mW cm−2 and charge-discharge cycle stability, and this suggests the potential application of CoC x /(Co 0.55 Fe 1.945) 2 P@C in energy transformation systems. The high electrocatalytic performances are revealed to originate from the change of electronic structure of bimetallic (Co 0.55 Fe 1.945) 2 P via introducing P into the Co 0.55 Fe 1.945 alloy, resulting in a decreased energy gap of CoC x /(Co 0.55 Fe 1.945) 2 P@C relative to that of CoC x /Co 0.55 Fe 1.945 @C. This work proposes a versatile strategy to develop multifunctional non-precious catalysts for this kind of energy-related electrocatalytic reactions. [ABSTRACT FROM AUTHOR]

The ultrafine Ni nanoparticles supported on carbon nanofiber are prepared via adsorption-pyrolyzation strategy and used as air electrodes to assemble flexible solid-state Zn-air battery. Development of well-designed bifunctional electrocatalysts with high activity for OER (oxygen evolution reaction) and ORR (oxygen reduction reaction) are a crucial topic owing to their promising applications in rechargeable Zinc (Zn)-air battery. Herein, a facile adsorption-pyrolyzation strategy is proposed for preparing ultrafine Ni nanoparticles anchored on carbon nanofiber (Ni/CNF), which derives from pyrolyzation of bacterial cellulose (BC) (with pre-adsorbed of Ni2+) via a two-step heat-treatment procedure (firstly 360 ℃, and then 750 ℃) (Ni/CNF-750) and used as an excellent oxygen electrocatalyst for flexible all solid-state Zn-air cell. The resultant ultrafine Ni/CNF-750 with plentiful pore structure and relatively high specific surface area of 449.0 m2 g−1, delivering overpotential of 293 mV at current density of 10 mA cm−2 for OER, obtaining an onset potential of 0.93 V vs. RHE and half-wave potential of 0.76 V vs. RHE for ORR. Moreover, a home-made flexible all solid-state battery is constructed by using Ni/CNF-750 as air electrodes, which provides a power density of 56.8 mW cm−2 and wonderful cycling durability with maintaining 50 cycles, and can drive a light-emitting-diode (LED) device. Our work may provides a reliable approach for fabricating ultrafine metal nanoparticles anchored on carbon based substrate with high activity for next-generation energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

Clean energy conversion/storage techniques have become increasingly significant because of the increasing energy consumption. Regarding practical applications like zinc-air batteries and supercapacitors, electrode materials are essential and often require both porous networks and active species to enhance their electrochemical performance. Nitrogen-doped porous carbon (NPC) is a kind of promising material, which provides efficient active sites and large surface areas for energy conversion/storage applications. However, rational modulation of properties for maximizing NPC performance is still a challenge. Herein, a promising NPC material derived from natural biomass is successfully synthesized by following a stepwise preparation method. Physisorption and X-ray photoelectron spectroscopy (XPS) analyses demonstrate both pore structures and nitrogen species of the NPC have been delicately tuned. The optimized sample NPC-800-m exhibits excellent performance in both oxygen reduction reaction (ORR) and three-electrode supercapacitor measurement. Moreover, the homemade zinc-air battery and symmetric supercapacitor assembled with NPC-800-m also display outstanding energy and power density as well as durable stability. Density functional theory (DFT) calculations further confirm the synergistic effects among graphitic, pyridinic and pyrrolic nitrogen. The existence of multispecies of nitrogen combined with the optimized pore structure is the key to the high electrochemical performance for NPC-800-m. This work not only provides feasible and green synthetic methodology but also offers original insights into the effective pores and the synergistic effects of different nitrogen species in the NPC materials. [ABSTRACT FROM AUTHOR]

• Cu-supported Ag Nanowires (Cu@AgNAs 1-5) are prepared under green solution. • Ag loading of Cu@AgNAs 1-5 is above 81 mg cm−2. • Cu@AgNAs 1-5 -Zn battery demonstrates an areal capacity of 36.8 mAh cm−2 at 10 mA cm−2. As one of the most mature battery systems, the silver-zinc battery holds huge promise in the field of aqueous rechargeable batteries due to superior performance, high safety and environmental friendliness. It is urgent to improve the areal capacity of silver-zinc batteries so far. This study reports a novel Cu-supported Ag Nanowires (Cu@AgNAs 1-5: abbreviation of Cu@AgNAs 1 , Cu@AgNAs 2 , Cu@AgNAs 3 , Cu@AgNAs 4 and Cu@AgNAs 5) as binder-free cathodes for high performance rechargeable aqueous silver-zinc batteries. Cu@AgNAs 1-5 are successfully prepared by two steps of electrochemical nanoengineering and mild galvanic replacement between Cu and [Ag(NH 3) 2 ]+ chelate ions under green solution. With ultrahigh Ag loading of above 81 mg cm−2, the Cu@AgNAs 5 cathode achieves ultrahigh areal capacity of above 36 mAh cm−2 at current density of 10 mA cm−2. Benefiting from synergistic effect of Ag and Cu, multiply twinned structure accompanied by lattice defections (such as lattice distortion, mismatch and dislocation) and heterostructures, the Cu@AgNAs 1-5 cathodes achieve excellent Ag utilization and cycling stability. Furthermore, the aqueous rechargeable Cu@AgNAs 5 -Zn battery demonstrates an excellent areal capacity of 36.80 mAh cm−2 at 10 mA cm−2. This work offers a promising pathway to greatly enhance areal capacity of bimetallic nanostructure-based electrodes and the Cu@AgNAs 1-5 -Zn batteries are attractive for large-scale energy-storage application. [ABSTRACT FROM AUTHOR]

Hollow electrode materials with structural advantages of large contact interface and sufficient cavity structures are significant for electrochemical energy storage. Herein, ultra-long one-dimensional zinc–manganese oxide (ZnMn 2 O 4) hollow nanofibers were successfully prepared by electrospinning at an appropriate temperature (500 °C). The optimal electrode of ZnMn 2 O 4 exhibited a larger specific capacitance (1026 F g−1) as compared to ZnMn 2 O 4 powder (125 F g−1) at a current density of 2 A g−1 in three-electrode configuration. Moreover, the optimal electrode of the ZnMn 2 O 4 hollow nanofibers also possessed long-term cycling stability with a slight upward capacitance (100.8%) after 5000 cycles. Their higher specific capacitance and the outstanding cycle stability may be attributed to the unique 1D hollow nanostructure, which enhanced the charge transfer and improved the diffusion of the electrolyte ions at the surface. Thus, this work designed a high-performance electrode with unique hollow nanostructure that can be applied to the field of energy storage. [ABSTRACT FROM AUTHOR]

A novel egg waffle–like architecture consisting of double–shell ZnMn 2 O 4 hollow microspheres embedded in 2D carbon networks is designed and exhibits excellent electrochemical properties when used as a cathode electrode material in aqueous zinc ion batteries. Currently, aqueous zinc–ion batteries are receiving extraordinary attention because of their cheap price, superior energy density and great security. However, the inferior specific capacity and low rate capability significantly hamper their further widespread application. Herein, a novel egg waffle–like architecture consisting of double–shell ZnMn 2 O 4 hollow microspheres embedded in 2D carbon networks (ZnMn 2 O 4 @C) is designed and employed as a cathode material for aqueous zinc–ion batteries. Specifically, the ZnMn 2 O 4 @C electrode displays a capacity of 481 mAh g−1 at 0.2 A g−1 after 110 cycles with excellent cycling stability. The superior cycling stability of the ZnMn 2 O 4 @C electrode is ascribed to the synergistic effect of the double–shell ZnMn 2 O 4 hollow microspheres, which offer sufficient space to withstand volume expansion during Zn2+ intercalation/deintercalation process, as well as the 2D continuous conductive and interconnected carbon network, which facilitates rapid electronic transmission and guarantees good structural mechanical stability. This study offers a fascinating cathode material and extends the available choices for manganate based–materials in rechargeable aqueous zinc–ion batteries. [ABSTRACT FROM AUTHOR]

Advanced aqueous batteries with abundant global reserves, large discharge capacity and long life span are crucial research objectives. Herein, a kind of aqueous Zn-ion battery was fabricated with ultra-thin Ni-Mn nanosheet electrode and zinc foil. A simple H 2 -annealing process was employed to handle the NiMn x O y nanosheets to form oxygen vacancy. Based on the formation of fast ion diffusion channels and the increase of active sites, the fabricated H-NiMn x O y nanosheet electrode displays an areal capacity of 0.68 mA h cm−2 at a current density of 2 mA cm−2 and an excellent cycling performance (almost no reduction after 6000 cycles). The fabricated H-NiMn x O y //Zn battery obtains a high areal capacity, up to 0.66 mA h cm−2 at a current density of 4 mA cm−2, and shows a long cycling stability (88.5% capacity retention after 5500 cycles). In particular, it has a high energy density, up to 1.13 mW cm−2 at a power density of 3.34 mW cm−2, more than many other similar devices. Thus, this research provides a new idea for the wide application of aqueous Zn-ion battery in intelligent equipment and electric vehicles. [ABSTRACT FROM AUTHOR]

• The Zn foil is coated by carbon black to enlarge the electroactive surface area. • Nanofibrillated cellulose is used as an effective binder to adhere carbon black. • The modified anode can eliminate the dendritic growth and side reactions. • Excellent interface stability between the anode and electrolyte is achieved. • The Zn-MnO 2 battery with modified anode shows significantly improved cyclability. Aqueous zinc-ion batteries have received significant attention due to their low cost and high safety. However, the unsatisfactory cycling performances caused by the dendritic growth on the Zn anode limit their practical applications. Herein, we propose to modify the conventional Zn foil anode by using carbon black coating and nanofibrillated cellulose binder. The carbon black can form an electrically conductive network, thus greatly enlarging the electroactive surface area, while the nanofibrillated cellulose can act as an electrolyte reservoir to facilitate charge transports. Thanks to that, the modified anode can significantly eliminate the dendritic growth and side reactions, therefore ensuring excellent interface stability with the electrolyte even at a commercial-level areal capacity of 5 mAh g−1. With the modified anode, the Zn-MnO 2 battery gives a high capacity retention of 87.4% after 1000 cycles, much higher than that with the unmodified Zn foil (42.6%). This study discloses a facile, scalable, and cost-effective strategy to achieve dendrite-free metal electrodes towards great cyclability. [ABSTRACT FROM AUTHOR]

• A new ceramic gas diffusion layer has been prepared via polymer derived ceramics. • 390 μm thick and 55% porous GDL is developed with the help of freeze tape casting. • GDL shows a bilayer with a thin denser layer followed by sponge-like backing layer. • The ceramic electrode shows the excellent performance in ZAB by breathing open air. • Sponge-like GDL facilitates the oxygen exchange rate and offers better kinetics. Rational material designs play a vital role in the gas diffusion layer (GDL) by increasing the oxygen diffusion rate and, consequently, facilitating a longer cycle life for metal-air batteries. In this work, a new porous conductive ceramic membrane has been developed as a cathodic GDL for zinc-air battery (ZAB). The bilayered structure with a thickness of 390 μm and an open porosity of 55% is derived from a preceramic precursor with the help of the freeze tape casting technique. The hydrophobic behaviour of the GDL is proved by the water contact angle of 137.5° after the coating of polytetrafluoroethylene (PTFE). The electrical conductivity of 5.59 * 10−3 S/cm is reached using graphite and MWCNT as filler materials. Tested in a ZAB system, the as-prepared GDL coated with commercial Pt-Ru/C catalyst shows an excellent cycle life over 200 cycles and complete discharge over 48 h by consuming oxygen from the atmosphere, which is comparable to commercial electrodes. The as-prepared electrode exhibits excellent ZAB performance due to the symmetric sponge-like structure, which facilitates the oxygen exchange rate and offers a short path for the oxygen ion/-electron kinetics. Thus, this work highlights the importance of a simple manufacturing process that significantly influences advanced ZAB enhancement. [ABSTRACT FROM AUTHOR]

Cost-effective electrocatalysts with excellent oxygen reduction reaction (ORR) activity are requisite for the commercial application fuel cells and zinc-air batteries. Herein, we prepare a series of carbon-based non-precious metal catalysts by simply carbonizing the mixture of FeCo-ZIF, melamine and soya-bean oil. The microstructure and electrochemical activity of the prepared catalysts highly depend on the adding amount of FeCo-ZIF. With proper addition, the FeCo-ZIF are transformed into Co 5.47 N and Co 0.72 Fe 0.28 alloy nanoparticles, which are embedded in the in situ formed carbon network consisted of nitrogen-doped graphene-like carbon nanosheets and interwoven carbon nanotubes. The resulted catalyst (FeCo@NCs-0.15) with considerable specific surface area and high pore volume demonstrates a superior ORR catalytic activity than commercial Pt/C with a half-wave potential (E 1/2) of 0.83 V (vs. RHE), onset potential (E onset) of 0.97 V (vs. RHE) and 4-electron dominated reaction path. The durability and methanol resistance are also better than that of commercial Pt/C in alkaline solution. This study provides an inexpensive, facile and scalable strategy to simultaneously realize non-precious metal-based active sites, nitrogen-doping, porosity and highly conductive carbon matrix in one electrocatalyst by one step. [ABSTRACT FROM AUTHOR]

Rechargeable nickel-zinc battery is regarded as a prospective choice for next-generation energy storage device due to its good safety, environmental friendliness and high energy density. However, zinc anode inevitably suffers from uncontrollable growth of zinc dendrites and the dissolution of zinc metal in high-concentration alkaline electrolytes, resulting in poor cycle stability and severely hampering the widespread applications of nickel-zinc batteries. Herein, a unique zinc anode with artificial solid electrolyte interface (ASEI) is facilely constructed via the rolling-tearing of tin and zinc foils and subsequent surface-based chemical reaction in a lead salt solution. The as-prepared ASEI composed of lead film has an efficient protective effect on preventing the dissolution of zinc anode. Meanwhile, the lead element and residual tin can not only enhance hydrogen evolution over-potential of zinc anode but affect the zinc growth mechanism. As a consequence, an excellent cyclic performances upto 100 cycles (capacity retention: 90%) with high reversible capacities are achieved for the zinc anode with AESI. [ABSTRACT FROM AUTHOR]

The resistive switching effect is a great physical phenomenon that the resistance of a material can be reversibly changed by applying an electric pulse, which is useful to constructing the nonvolatile resistance random access memory (RRAM) in the next generation of memory system. In this work, a sandwich structure (ITO/WO 3 /AZO) was prepared by using WO 3 film (∼300 nm) as the dielectric layer meanwhile indium tin oxide (ITO) as the top electrode and aluminium-doped zinc oxide (AZO) as the bottom electrode. An enhanced resistive switching memory behavior was observed in the sample processed by light-illumination. Furthermore, the set voltage (V set) and reset voltage (V reset) are increased but the HRS/LRS resistance ratio is decreased with the increasing of illumination time for 600 °C annealed sample. Through further analysis, a physical model on the tunneling of photon-generated carrier in the Schottky barrier layer driven by electric pulse is proposed to explain the enhanced resistive switching memory behavior. The suggested mechanism is highly pivotal for the resistive switching phenomenon to be properly applied in the nonvolatile RRAM device. [ABSTRACT FROM AUTHOR]