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Wenhao Ren

Bio: Wenhao Ren is an academic researcher from University of New South Wales. The author has contributed to research in topics: Anode & Electrolyte. The author has an hindex of 23, co-authored 59 publications receiving 2286 citations. Previous affiliations of Wenhao Ren include Southwest Petroleum University & Wuhan University of Technology.

Papers published on a yearly basis

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Journal ArticleDOI
TL;DR: Density functional theory studies reveal that the neighboring Ni-Fe centers not only function in synergy to decrease the reaction barrier for the formation of COOH* and desorption of CO, but also undergo distinct structural evolution into a CO-adsorbed moiety upon CO2 uptake.
Abstract: Polynary single-atom structures can combine the advantages of homogeneous and heterogeneous catalysts while providing synergistic functions based on different molecules and their interfaces. However, the fabrication and identification of such an active-site prototype remain elusive. Here we report isolated diatomic Ni-Fe sites anchored on nitrogenated carbon as an efficient electrocatalyst for CO2 reduction. The catalyst exhibits high selectivity with CO Faradaic efficiency above 90 % over a wide potential range from -0.5 to -0.9 V (98 % at -0.7 V), and robust durability, retaining 99 % of its initial selectivity after 30 hours of electrolysis. Density functional theory studies reveal that the neighboring Ni-Fe centers not only function in synergy to decrease the reaction barrier for the formation of COOH* and desorption of CO, but also undergo distinct structural evolution into a CO-adsorbed moiety upon CO2 uptake.

592 citations

Journal ArticleDOI
TL;DR: A gradient electrospinning and controlled pyrolysis method to synthesize various controllable 1D nanostructures, including mesoporous nanotubes, pea-like nanot tubes and continuous nanowires, is designed.
Abstract: Nanowires and nanotubes have been the focus of considerable efforts in energy storage and solar energy conversion because of their unique properties. However, owing to the limitations of synthetic methods, most inorganic nanotubes, especially for multi-element oxides and binary-metal oxides, have been rarely fabricated. Here we design a gradient electrospinning and controlled pyrolysis method to synthesize various controllable 1D nanostructures, including mesoporous nanotubes, pea-like nanotubes and continuous nanowires. The key point of this method is the gradient distribution of low-/middle-/high-molecular-weight poly(vinyl alcohol) during the electrospinning process. This simple technique is extended to various inorganic multi-element oxides, binary-metal oxides and single-metal oxides. Among them, Li3V2(PO4)3, Na0.7Fe0.7Mn0.3O2 and Co3O4 mesoporous nanotubes exhibit ultrastable electrochemical performance when used in lithium-ion batteries, sodium-ion batteries and supercapacitors, respectively. We believe that a wide range of new materials available from our composition gradient electrospinning and pyrolysis methodology may lead to further developments in research on 1D systems.

356 citations

Journal ArticleDOI
TL;DR: In this article, a microwave induced exfoliation strategy was used to extract hard carbon from a conventional soft carbon compound obtained by pyrolysis of 3,4,9,10-perylene tetracarboxylic dianhydride.
Abstract: DOI: 10.1002/aenm.201803260 lithium-ion batteries (LIBs) cannot meet the increasing requirement of large-scale energy storage due to the limited and high cost of lithium resources.[4,5] Other alkali metals (especially sodium and potassium) are recognized as alternatives to lithium owing to abundance of elemental source and geographical distribution.[6–8] While the lithium and sodium share common properties as alkali metals, the assumption of adapting the same electrode materials from LIBs to sodium-ion batteries (SIBs) is not always efficacious.[9–11] The intrinsically higher redox potential of Na+/Na compared with Li+/Li (−2.71 > −3.04 V vs standard hydrogen electrode) and the sluggish Na+ transport resulting from the larger radius of Na+ compared with Li+ (1.02 > 0.76 Å) directly affect the electrochemical performance.[10] As the most common anode for commercial LIBs, graphite exhibits superior reversible capacity (close to its theoretical capacity of 372 mAh g−1) as a result of consecutive migration of Li+ between layered structures to forming LiC6. Nevertheless, as demonstrated by previous reports, both the experiment carried out by Doeff et al.[14] and the theoretical calculation performed via Density Functional Theory studies by Wang et al.[15] in 2014 prove that it is hard to form sodium intercalated graphite compounds.[16,17] Only a small amount of Na+ can be stored in graphite, leading to the suppressed reversible capacity of ≈30 mAh g−1.[11,18,19] In contrast to the graphite, the nongraphitizable hard carbon and graphitizable nongraphitic soft carbon have attracted most attentions as anodes for SIBs on account of their high capacity.[20,21] The sodiation of hard carbon at room temperature has been first reported by Stevens and Dahn,[22] achieving a capacity of ≈300 mAh g−1. A insertion–absorption process named as “house of cards” has been introduced at the same time and further proved by in situ small angle X-ray scattering study, which ascribes the sodiation to insertion of Na-ions and metallic adsorption (deposition) into the pores.[23,24] After that, other sodium storage mechanisms of hard carbon called “absorption-insertion” and “absorptionfilling” have been introduced by Cao et al.[25] and Tarascon and co-workers,[26] respectively.[27] Considering the safety concern Soft carbon has attracted tremendous attention as an anode in rocking-chair batteries owing to its exceptional properties including low-cost, tunable interlayer distance, and favorable electronic conductivity. However, it fails to exhibit decent performance for sodium-ion storage owing to difficulties in the formation of sodium intercalation compounds. Here, microporous soft carbon nanosheets are developed via a microwave induced exfoliation strategy from a conventional soft carbon compound obtained by pyrolysis of 3,4,9,10-perylene tetracarboxylic dianhydride. The micropores and defects at the edges synergistically leads to enhanced kinetics and extra sodiumion storage sites, which contribute to the capacity increase from 134 to 232 mAh g−1 and a superior rate capability of 103 mAh g−1 at 1000 mA g−1 for sodium-ion storage. In addition, the capacitance-dominated sodium-ion storage mechanism is identified through the kinetics analysis. The in situ X-ray diffraction analyses are used to reveal that sodium ions intercalate into graphitic layers for the first time. Furthermore, the as-prepared nanosheets can also function as an outstanding anode for potassium-ion storage (reversible capacity of 291 mAh g−1) and dual-ion full cell (cell-level capacity of 61 mAh g−1 and average working voltage of 4.2 V). These properties represent the potential of soft carbon for achieving high-energy, high-rate, and low-cost energy storage systems.

231 citations

Journal ArticleDOI
TL;DR: A controllable selective etching approach is developed for the synthesis of Prussian blue analogue (PBA) with enhanced sodium storage activity and a defect-induced morphological evolution mechanism from nanocube to nanoflower structure is proposed to provide higher Na+ diffusion dynamics and negligible volume change during the sodiation/desodiation processes.
Abstract: Sodium-ion battery technologies are known to suffer from kinetic problems associated with the solid-state diffusion of Na+ in intercalation electrodes, which results in suppressed specific capacity and degraded rate performance. Here, a controllable selective etching approach is developed for the synthesis of Prussian blue analogue (PBA) with enhanced sodium storage activity. On the basis of time-dependent experiments, a defect-induced morphological evolution mechanism from nanocube to nanoflower structure is proposed. Through in situ X-ray diffraction measurement and computational analysis, this unique structure is revealed to provide higher Na+ diffusion dynamics and negligible volume change during the sodiation/desodiation processes. As a sodium ion battery cathode, the PBA exhibits a discharge capacity of 90 mA h g-1, which is in good agreement with the complete low spin FeLS(C) redox reaction. It also demonstrates an outstanding rate capability of 71.0 mA h g-1 at 44.4 C, as well as an unprecedented cycling reversibility over 5000 times.

214 citations

Journal ArticleDOI
TL;DR: In this article, an outside-in morphological evolution mechanism from microsphere to 3D nanofiber network is proposed based on time-dependent experiments, and the as-synthesized material exhibits excellent cyclability (95.9% capacity retention over 1000 cycles at 10C) and enhanced high-rate performance (94.1% at 100C) for sodium half cell.

206 citations


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TL;DR: This work aims to provide a comprehensive overview of electrospun nanofibers, including the principle, methods, materials, and applications, and highlights the most relevant and recent advances related to the applications by focusing on the most representative examples.
Abstract: Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

2,289 citations

Journal ArticleDOI
TL;DR: The results suggest that the H2 O-solvated Zn2+ possesses largely reduced effective charge and thus reduced electrostatic interactions with the V2 O5 framework, effectively promoting its diffusion.
Abstract: Low-cost, environment-friendly aqueous Zn batteries have great potential for large-scale energy storage, but the intercalation of zinc ions in the cathode materials is challenging and complex. Herein, the critical role of structural H2O on Zn2+ intercalation into bilayer V2O5·nH2O is demonstrated. The results suggest that the H2O-solvated Zn2+ possesses largely reduced effective charge and thus reduced electrostatic interactions with the V2O5 framework, effectively promoting its diffusion. Benefited from the “lubricating” effect, the aqueous Zn battery shows a specific energy of ≈144 Wh kg−1 at 0.3 A g−1. Meanwhile, it can maintain an energy density of 90 Wh kg−1 at a high power density of 6.4 kW kg−1 (based on the cathode and 200% Zn anode), making it a promising candidate for high-performance, low-cost, safe, and environment-friendly energy-storage devices.

987 citations

08 Jul 2010
TL;DR: Layer-by-layer techniques are used to assemble an electrode that consists of additive-free, densely packed and functionalized multiwalled carbon nanotubes, which had a gravimetric energy approximately 5 times higher than conventional electrochemical capacitors and power delivery approximately 10 timesHigher than conventional lithium-ion batteries.
Abstract: Energy storage devices that can deliver high powers have many applications, including hybrid vehicles and renewable energy. Much research has focused on increasing the power output of lithium batteries by reducing lithium-ion diffusion distances, but outputs remain far below those of electrochemical capacitors and below the levels required for many applications. Here, we report an alternative approach based on the redox reactions of functional groups on the surfaces of carbon nanotubes. Layer-by-layer techniques are used to assemble an electrode that consists of additive-free, densely packed and functionalized multiwalled carbon nanotubes. The electrode, which is several micrometres thick, can store lithium up to a reversible gravimetric capacity of approximately 200 mA h g(-1)(electrode) while also delivering 100 kW kg(electrode)(-1) of power and providing lifetimes in excess of thousands of cycles, both of which are comparable to electrochemical capacitor electrodes. A device using the nanotube electrode as the positive electrode and lithium titanium oxide as a negative electrode had a gravimetric energy approximately 5 times higher than conventional electrochemical capacitors and power delivery approximately 10 times higher than conventional lithium-ion batteries.

953 citations

Journal ArticleDOI
TL;DR: The strategies and perspectives summarized in this review aim to provide practical guidance for an increasing number of researchers to explore next-generation and high-performance PIBs, and the methodology may also be applicable to developing other energy storage systems.
Abstract: Potassium-ion batteries (PIBs) have attracted tremendous attention due to their low cost, fast ionic conductivity in electrolyte, and high operating voltage. Research on PIBs is still in its infancy, however, and achieving a general understanding of the drawbacks of each component and proposing research strategies for overcoming these problems are crucial for the exploration of suitable electrode materials/electrolytes and the establishment of electrode/cell assembly technologies for further development of PIBs. In this review, we summarize our current understanding in this field, classify and highlight the design strategies for addressing the key issues in the research on PIBs, and propose possible pathways for the future development of PIBs toward practical applications. The strategies and perspectives summarized in this review aim to provide practical guidance for an increasing number of researchers to explore next-generation and high-performance PIBs, and the methodology may also be applicable to developing other energy storage systems.

744 citations