Morphology-dependent performance of CuO anodes via facile and controllable synthesis for lithium-ion batteries

Carbon Nanotubes Connecting and Encapsulating MoS2-Doped SnO2 Nanoparticles as an Excellent Lithium Storage Performance Anode Material

Doping and carbon encapsulation modifications have been proven to be effective methods for enhancing the lithium storage performance of batteries. The hydrothermal method and ball milling are commonly used methods for material synthesis. In this study, a composite anode material rich in carbon nanotubes (CNTs) conductive tubular network connection and encapsulation of SnO2-MoS2@CNTs (SMC) was synthesized by combining these two methods. In this highly conductive network, nano-SnO2 particles are uniformly dispersed and embedded in MoS2 with a layered structure, and the obtained SnO2-MoS2 composite material is tightly connected and encapsulated by the tubular network of CNTs. It is worth noting that the incorporation of layered MoS2 not only effectively anchors the SnO2 nanoparticles, but also provides a broader space for lithium-ion movement due to the larger interlayer spacing. The conductive network of CNTs shortens the diffusion path of electrons and Li+ and provides more diffusion channels. The reversible capacity of the SnO2-MoS2@CNTs nanocomposite material remains at 1069.3 mA h g-1 after 320 cycles at 0.2 A g-1, and it exhibits excellent long-term cycling stability, maintaining 904.5 mA h g-1 after 1000 cycles at 1.0 A g-1. The composite material demonstrates excellent pseudocapacitive contribution rate performance, with a contribution rate of 87% at 2.0 mV s-1. The results indicate that SnO2-MoS2@CNTs has excellent electrochemical lithium storage performance and is a promising anode material for lithium-ion batteries.

Fabrication of binary metal-organic frameworks of Ni-Mn@ZIFs(Cox·Zn1-xO) decorated on CF/CuO nanowire for high-performance electrochemical pseudocapacitors

Herein, metal-organic frameworks (MOFs) derived nanoflower-like based binary transition metal (Ni-Mn) are successfully fabricated by a simple synthesis method. The fabricated nanoflower-like structure displays a unique nanoflower-like architecture and internal porous channels constructed by MOF coated on CuO/CF/ZIFs (Cox·Zn1-xO) substrate, which is beneficial for the penetration of electrolyte and electron/ion transportation. The as-prepared CF/CuO/ZIFs (Cox·Zn1-xO)@BMOF(Ni-Mn) electrode materials present significant synergy among transition metal ions, contributing to enhanced electrochemical performances. The as-prepared CF/CuO/ZIFs (Cox·Zn1-xO)@BMOF(Ni-Mn) hybrid nanoflower-like display a high specific capacity of 1249.99 C g-1 at 1 A g-1 and the specific capacitance retention is about 91.74% after 5000 cycles. In addition, the as-assembled CF/CuO/ZIFs (Cox·Zn1-xO)@BMOF(Ni-Mn)//AC asymmetric supercapacitor (ASC) device exhibited a maximum energy density of 21.77 Wh·kg-1 at a power density of 799 W kg-1, and the capacity retention rate after 5000 charge and discharge cycles was 88.52%.

Fabrication of nano-hammer shaped CuO@HApNWs for catalytic degradation of tetracycline

With widespread and excessive use of antibiotics in medicine, poultry farming, and aquaculture, antibiotic residues have become a significant threat to both eco-environment and human health. In this paper, using hydroxyapatite nanowires (HApNWs) as an ecologically compatible carrier, a novel nano-hammer shaped conjunction with HApNW conjugating CuO microspheres (CuO@HApNWs) was successfully synthesized by in-situ agglomeration method. The catalytic degradation performance of the nano-hammer shaped CuO@HApNWs with Fenton-like activation was investigated by using tetracycline (TC) as a representative antibiotic pollutant. Remarkably, it exhibited excellent catalytic activity, which the removal rate of TC got to 92.0% within 40 min, and the pseudo-second-order reaction kinetic constant was 18.33 × 10-3 L mg-1·min-1, which was 26 times and 5 times than that of HApNWs and CuO, respectively. Furthermore, after recycling 6 times, the degradation efficiency of TC still remained above 85 %. Based on radical scavenger tests and electron paramagnetic resonance (EPR) spectroscopy, it demonstrated that the excellent activity of CuO@HApNWs was mainly attributed to the fact that Fenton-like activation promotes the circulation of Cu2+ and Cu+, the generated main active oxygen species (•OH and O2-•) achieve efficient degradation of TC. In summary, the nano-hammer shaped CuO@HApNWs could be in-situ synthesed, and used as an eco-friendly Fenton-like catalyst for effectively catalytic degradation of organic pollutants, which has great potential for wastewater treatment.

CuO/Cu/rGO nanocomposite anodic titania nanotubes for boosted non-enzymatic glucose biosensors

Highly arranged porous anodic titania (TiO2) nanotube arrays (ATNT) were fruitfully fabricated by the anodization of Ti foil in an ammonium fluoride electrolyte.

A phase transition-induced photocathodic p-CuFeO2 nanocolumnar film by reactive ballistic deposition

Vertical nanocolumnar Cu–Fe–O electrodes synthesized by the reactive ballistic deposition technique followed by heat treatment in an Ar atmosphere undergo a switch for conductivity at elevated temperatures.

The Synergetic Effect Induced High Electrochemical Performance of CuO/Cu2O/Cu Nanocomposites as Lithium-Ion Battery Anodes

Due to the high theoretical capability, copper-based oxides were widely investigated. A facile water bath method was used to synthesis CuO nanowires and CuO/Cu₂O/Cu nanocomposites. Owing to the synergetic effect, the CuO/Cu₂O/Cu nanocomposites exhibit superior electrochemical performance compared to the CuO nanowires. The initial discharge and charge capacities are 2,660.4 mAh/g and 2,107.8 mAh/g, and the reversible capacity is 1,265.7 mAh/g after 200 cycles at 200 mA/g. Moreover, the reversible capacity is 1,180 mAh/g at 800 mA/g and 1,750 mAh/g when back to 100 mA/g, indicating the excellent rate capability. The CuO/Cu₂O/Cu nanocomposites also exhibit relatively high electric conductivity and lithium-ion diffusion coefficient, especially after cycling. For the energy storage mechanism, the capacitive controlled mechanism is predominance at the high scan rates, which is consistent with the excellent rate capability. The outstanding electrochemical performance of the CuO/Cu₂O/Cu nanocomposites indicates the potential application of copper-based oxides nanomaterials in future lithium-ion batteries.

Complementary Effects of Mg and Cu Incorporation in Stabilizing the Cobalt-Free LiNiO2 Cathode for Lithium-Ion Batteries

Since the discovery of LiNiO₂ several decades ago, a new era of electric vehicles demanding high-energy-density lithium-ion batteries (LIBs) has recently rebooted the interest in this cathode material to eliminate the dependence on expensive and scarcely available cobalt. However, LiNiO₂ has been plagued by cycle instability, thermal instability, and air instability. We present here an exploration of the mutual interaction of magnesium and copper in stabilizing the cobalt-free LiNiO₂ cathode. Although Mg doping is beneficial for the robustness of the bulk structure of LiNiO₂, surface characterization results of Mg-doped LiNiO₂ implies the need for further surface protection. To that end, we have incorporated Cu in addition to Mg in that Cu stabilizes the surface of Mg-doped LiNiO₂ by forming a protective stable surface layer without harming the bulk. Notable variations of the surface residual lithium composition (Li_Li2CO3/Li_LiOH) along with the incorporation of stabilizers are also discussed. The harmony between Mg and Cu with as little as 0.5 atom % Mg and 0.3 atom % Cu significantly enhances the specific energy and cycle life of LiNiO₂. This study demonstrates how the co-incorporation of optimal dopants can help stabilize both the bulk and surface and provides new insights toward developing cobalt-free layered oxide cathodes for high-energy-density LIBs.

Anion-induced morphological regulation of cupric oxide nanostructures and their application as co-catalysts for solar water splitting

Morphological control of nanomaterials is essential for their properties and potential applications, and many strategies have been developed. In this work, a new strategy for simultaneously preparing and modulating the morphological structure evolution of copper layered hydroxyl salts and oxides is introduced. By changing the nature of the anions in the electroplating solution, significant variations in the size and porosity of nanosheets are achieved. Porous CuO nanosheets with a higher surface area were obtained by the use of copper nitrate as a copper source, while CuO nanoflakes were produced from copper sulfate. Photoanodes combining these porous CuO nanomaterials and a typical light absorber (BiVO₄) exhibited good morphology-dependent activities for photoelectrochemical water splitting. The composite electrode displays a negative shift of 180 mV for the onset potential and an approximately 2-fold enhancement in the photocurrent compared to the bare BiVO₄. The charge recombination rate in the photoelectrode with the porous CuO nanosheets was significantly lower than the bare photoanode due to the favorable electron diffusion path and effective charge collection. This research offers an effective method for constructing a highly active photoelectrocatalytic system for overall water splitting.

In Situ Precipitation-Induced Growth of Leaf-like CuO Nanostructures on Cu-Ni Alloys for Binder-Free Anodes in Li-Ion Batteries

CuC₂ O₄ ⋅x H₂ O was facilely prepared on a Cu-Ni alloy substrate by in situ precipitation-induced growth by using a mixture of sodium persulfate, hydrogen peroxide, and oxalic acid. Thermal annealing allowed the conversion of CuC₂ O₄ ⋅x H₂ O to leaf-like CuO nanostructures with a thickness of a few tens of micrometers of sub-sized nanoparticles, which were applied for fabricating binder-free anodes for lithium-ion batteries. Ni was a nucleation site for CuC₂ O₄ ⋅x H₂ O, which was uniformly formed on the entire substrate. The concentration of each component in the mixture solution caused significant morphological changes because of the different elution of copper ions. CuO nanostructures annealed at 550 °C showed large areal and gravimetric capacity with excellent capacity retention of 95.5 % after 200 cycles at a high current density because of their appropriate structural morphology, which not only allowed the formation of a stable solid electrolyte interphase layer but also enabled a reversible reaction during the charge/discharge process.

In-Situ Growing Mesoporous CuO/O-Doped g-C3N4 Nanospheres for Highly Enhanced Lithium Storage

The development of lithium-ion batteries using transition metal oxides has recently become more attractive, due to their higher specific capacities, better rate capability, and high energy densities. Herein, the in situ growth of advanced mesoporous CuO/O-doped g-C₃N₄ nanospheres is carried out in a two step hydrothermal process at 180 °C and annealing in air at 300 °C. When used as an anode material, the CuO/O-doped g-C₃N₄ nanospheres achieve a high reversible discharge specific capacity of 738 mAhg^-1 and a capacity retention of ∼75.3% after 100 cycles at a current density 100 mAg^-1 compared with the pure CuO (412 mAhg^-1, 47%) and O-doped g-C₃N₄ (66 mAhg^-1, 53%). Even at high current density 1 Ag^-1, they exhibit a reversible discharge specific capacity of 503 mAhg^-1 and capacity retention ∼80% over 500 cycles. The excellent electrochemical performance of the CuO/O-doped g-C₃N₄ nanocomposite is attributed to the following factors: (I) the in situ growing CuO/O-doped g-C₃N₄ avoids CuO nanoparticle aggregation, leading to the improved lithium ion transfer and electrolyte penetration inside the CuO/O-doped g-C₃N₄ anode, thus promoting the utilization of CuO; (II) the porous structure provides efficient space for Li⁺ transfer during the insertion/extraction process to avoid large volume changes; (III) the O-doping g-C₃N₄ decreases its band gap, ensuring the increased electrical conductivity of CuO/O-doped g-C₃N₄; and (IV) the strong interaction between CuO and O-doped g-C₃N₄ ensures the stability of the structure during cycling.

Magnetic Cu/Fe3O4@FeOOH with intrinsic HRP-like activity at nearly neutral pH for one-step biosensing

The convenience of colorimetric sensors is useful for practical applications. In this work, we constructed a novel colorimetric sensor with magnetic separation ability that can be operated in nearly neutral conditions and achieve one-step detection of metabolites. Magnetic Cu doped Fe₃O₄@FeOOH magnetic nanocomposite (Cu/Fe₃O₄@FeOOH) with an oxygen vacancy was prepared by a one-step self-assembly hydrothermal method, and fully characterized by different methods. The oxygen vacancy generated by the incorporation of Cu²⁺ cations into the Fe₃O₄@FeOOH structure was confirmed to be a vital reactive site for enhancing the catalytic activity, which opens up a new way of designing highly efficient enzyme mimics. Benefiting from its inherent horseradish-peroxidase-like activity, a simple and selective enzyme-based colorimetric sensor was developed for one-step detection of H₂O₂ and cholesterol, and 3,3',5,5'-tetramethylbenzidine was catalyzed by H₂O₂ to generate a colored product of oxidized 3,3',5,5'-tetramethylbenzidine for signaling. H₂O₂ and cholesterol can be linearly detected in the same range from 0.01 to 0.4 mmol L^-1 with detection limits of 0.0075 mmol L^-1 and 0.0082 mmol L^-1, respectively. The proposed colorimetric sensor has satisfactory reusability, accuracy, and practicability in human serum samples, indicating its potential application for the detection of different metabolites in the fields of life science and analytical science. Graphical abstract.

Electrospun Carbon/Cu x O Nanocomposite material as Sustainable and High Performance Anode for Lithium-Ion Batteries

The increase in energy density of the next generation of battery materials to meet the new challenges of the electrical vehicles era calls for innovative and easily scalable materials with sustainable processes. An innovative Cu x O/C nanocomposite material, characterized by a highly conductive 3D-framework, with Cu x O/Cu-metal contiguous nanodomains is prepared by electrospinning. The electrode processing is made using a polyacrylic acid binder. The nanocomposite has been fully characterized and the electrochemical performance shows high specific capacity values over 450 galvanostatic cycles at 500 mAg-1 specific current with capacity retention values over 80 %. In addition, the composite shows remarkable high rate performance and highly stable interface, which has been studied by impedance spectroscopy.

Nanostructural and Electrochemical Evolution of the Solid-Electrolyte Interphase on CuO Nanowires Revealed by Cryogenic-Electron Microscopy and Impedance Spectroscopy

Battery performance is critically dependent on the nanostructure and electrochemical properties of the solid-electrolyte interphase (SEI)-a passivation film that exists on most lithium-battery anodes. However, knowledge of how the SEI nanostructure forms and its impact on ionic transport remains limited due to its sensitivity to transmission electron microscopy and difficulty in accurately probing the SEI impedance. Here, we track the voltage-dependent, stepwise evolution of the nanostructure and impedance of the SEI on CuO nanowires using cryogenic-electron microscopy (cryo-EM) and electrochemical impedance spectroscopy (EIS). In carbonate electrolyte, the SEI forms at 1.0 V vs Li/Li⁺ as a 3 nm thick amorphous SEI and grows to 4 nm at 0.5 V; as the potential approaches 0.0 V vs Li/Li⁺, the SEI on the CuO nanowires forms an 8 nm thick inverted multilayered nanostructure in ethylene carbonate/diethyl carbonate (EC/DEC) electrolyte with 10 vol % fluoroethylene carbonate (FEC) and a mosaic nanostructure in EC/DEC electrolyte. Upon Li deposition, the total SEI thickness grows to 16 nm, and significant growth of the inner amorphous layer takes place in the inverted multilayered nanostructure, indicating that electrolyte permeates the SEI. Using a refined EIS methodology, we isolate the SEI impedance on Cu and find that the SEI nanostructure directly correlates to macroscopic Li-ion transport through the SEI. The inverted layered nanostructure decreases the interfacial impedance upon formation, whereas the mosaic nanostructure continually increases the interfacial impedance during growth. These structural and electrochemical findings illustrate a more complete portrait of SEI formation and guide further improvements in engineered SEI.

Co3Sn2/SnO2 nanocomposite loaded on Cu foam as high-performance three-dimensional anode for lithium-ion batteries

It is a challenge to commercialize tin dioxide-based anodes for lithium-ion batteries due to their low rate capability and poor cycling performance of the electrodes.

Fast-Charging and High Volumetric Capacity Anode Based on Co3 O4 /CuO@TiO2 Composites for Lithium-Ion Batteries

This paper presents an investigation of anodic TiO₂ nanotube arrays (TNAs), with a Co₃ O₄ /CuO coating, for lithium-ion batteries (LIBs). The coated TNAs are investigated using various analytical techniques, with the results clearly suggesting that the molar ratio of Co₃ O₄ /CuO in the TiO₂ nanotubes substantially influences its battery performance. In particular, a cobalt/copper molar ratio of 2:1 on the TNAs (Co₂ Cu₁ @TNAs) features the best LIBs anode performance, exhibiting high reversible capacity and enhanced cycling stability. Noticeably, Co₂ Cu₁ @TNAs achieve excellent rate capability even after quite a high current density of 20.0 A g^-1 (≈25 C, where C corresponds to complete discharge in 1 h) and superior volumetric reversible capacity of ≈3330 mA h^-1  cm^-3 . This value is approximately seven times higher than those of a graphite-based anode. This outstanding performance is attributed to the synergistic effects of Co₂ Cu₁ @TNAs: 1) the structural advantage of TNAs, with their large amount of free space to accommodate the large volume expansion during Li⁺ insertion/extraction and 2) the optimized ratio of Co₃ O₄ and CuO in the composite for improved capacity. In addition, no binder or conductive agent is used, which is partly responsible for the overall improved volumetric capacity and electrochemical performance.

Alkyldimethylbetaine-Assisted Development of Hollow Urchinlike CuO Microspheres and Application for High-Performance Battery Anodes

A new approach to develop novel hollow urchinlike copper oxide (CuO) microspheres by the hydrothermal method was reported, and zwitterionic alkyldimethylbetaine (BS) surfactants were employed as templates in the classic copper-ammonia complex systems. Effects of numerous environmental factors on the morphology of CuO particles were studied systematically, in which the concentration and structure of BS predominantly affected the developed CuO materials. It was noticed that hollow urchinlike CuO microspheres were generally formed in the presence of BS regardless of the reaction temperature and time and the source of copper ions. Generally speaking, high concentrations of BS and BS with longer chain length strongly favored the formation of hollow urchinlike CuO microspheres. The microstructures of synthesized CuO particles were studied in detail, and the corresponding formation mechanism of hollow urchinlike CuO microspheres was also proposed based on the selective adsorption of BS on the particular crystal facets of CuO crystals. Moreover, hollow urchinlike CuO microspheres showed excellent performance in the lithium-ion batteries as anode materials with a reversible capability of 511 mA h·g^-1 at 0.1 C after 40 charge-discharge cycles, which was one of the best values of CuO materials reported in this field.

High entropy oxides for reversible energy storage

In recent years, the concept of entropy stabilization of crystal structures in oxide systems has led to an increased research activity in the field of “high entropy oxides”. These compounds comprise the incorporation of multiple metal cations into single-phase crystal structures and interactions among the various metal cations leading to interesting novel and unexpected properties. Here, we report on the reversible lithium storage properties of the high entropy oxides, the underlying mechanisms governing these properties, and the influence of entropy stabilization on the electrochemical behavior. It is found that the stabilization effect of entropy brings significant benefits for the storage capacity retention of high entropy oxides and greatly improves the cycling stability. Additionally, it is observed that the electrochemical behavior of the high entropy oxides depends on each of the metal cations present, thus providing the opportunity to tailor the electrochemical properties by simply changing the elemental composition.

High entropy oxides provide a new strategy toward materials design by stabilizing single-phase crystal structures composed of multiple cations. Here, the authors apply this concept to the development of conversion-type electrode materials for lithium-ion storage and show the underlying mechanism.

Metal-organic framework-derived mesoporous octahedral copper oxide/titania composites for high-performance lithium-ion batteries

A mesoporous octahedral copper oxide@titania (CuO/TiO₂) composites with core-shelled structure have been successfully fabricated via a facile and cost-effective approach, which involves two main steps: the creation of homogeneous TiO₂ shell onto the octahedral Cu-based metal-organic frameworks (MOFs) template and thermal decomposition of the template at controlled temperature in the air. The design of combining CuO with the TiO₂ layer within a porous octahedra structure is beneficial to integrate the advantages of different components and address the severe volume change associated with pulverization issue that exists in most metal oxides-based electrodes. When assembled as an anode material for lithium-ion batteries, the as-fabricated mesoporous CuO/TiO₂ octahedra can achieve outstanding electrochemical performance in terms of a high reversible capacity (692 mAh g^-1 at 100 mA g^-1 for over 200 cycles) and exceptional rate capability (441 and 387 mA h g^-1 at 1600 and 3200 mA g^-1, respectively).

Yucca fern shaped CuO nanowires on Cu foam for remitting capacity fading of Li-ion battery anodes

To remit capacity fading of lithium ion battery (LIB) anodes, freestanding yucca fern shaped CuO nanowires (NWs) on Cu foams are fabricated as anodes by combining facile and scalable anodization of copper foams followed by calcination. The porous and radial configuration of the hierarchical CuO NWs on the Cu foam substrate guarantees the remarkably improved electrochemical performance with durable cycle stability and excellent rate capability compared with CuO NWs on Cu foils. The reversible capacity remains 461.5 mAh/g after 100 repeated cycles at a current density of 100 mA/g, and a capacity of 150.6 mAh/g even at a high rate of 1000 mA/g. By examining the surface morphology of the cycled samples, possible performance fading route is proposed. The 3D CuO NWs network with a porous architecture simutaneously reduces the ion diffusion distances, promotes the electrolyte permeation and electronic conductivity. This novel strategy might open a new window to develop durable CuO based composite anodes for LIBs.

A Single-Step Hydrothermal Route to 3D Hierarchical Cu2 O/CuO/rGO Nanosheets as High-Performance Anode of Lithium-Ion Batteries

As anodes of Li-ion batteries, copper oxides (CuO) have a high theoretical specific capacity (674 mA h g^-1 ) but own poor cyclic stability owing to the large volume expansion and low conductivity in charges/discharges. Incorporating reduced graphene oxide (rGO) into CuO anodes with conventional methods fails to build robust interaction between rGO and CuO to efficiently improve the overall anode performance. Here, Cu₂ O/CuO/reduced graphene oxides (Cu₂ O/CuO/rGO) with a 3D hierarchical nanostructure are synthesized with a facile, single-step hydrothermal method. The Cu₂ O/CuO/rGO anode exhibits remarkable cyclic and high-rate performances, and particularly the anode with 25 wt% rGO owns the best performance among all samples, delivering a record capacity of 550 mA h g^-1 at 0.5 C after 100 cycles. The pronounced performances are attributed to the highly efficient charge transfer in CuO nanosheets encapsulated in rGO network and the mitigated volume expansion of the anode owing to its robust 3D hierarchical nanostructure.

Synthesis of carbon nanotube (CNT)-entangled CuO nanotube networks via CNT-catalytic growth and in situ thermal oxidation as additive-free anodes for lithium ion batteries

We demonstrated the utility of carbon nanotubes (CNTs) as a catalyst and conductive agent to synthesize CNT-entangled copper nanowire (CuNW-CNT) networks within a melted mixture of hexadecylamine and cetyltrimethy ammounium bromide. The CuNW-CNT networks were further in situ thermally oxidized into CuO nanotube-CNT (CuONT-CNT) with the high retention of network structure. The binder- and conducting-additive-free anodes constructed using the CuONT-CNT networks exhibited high performance, such as high capability (557.7 mAh g^-1 at 0.2 °C after 200 cycles), high Coulombic efficiency (near 100%), good rate performance (385.5 mAh g^-1 at 5 °C and 310.3 mAh g^-1 at 10 °C), and long cycling life.

Ion exchange for synthesis of porous CuxO/SnO2/ZnSnO3 microboxes as a high-performance lithium-ion battery anode

Integrating other oxides and ZnSnO₃ with porous structures can accommodate volume expansion and enhance the electrochemical performance.

Morphological enhancement to CuO nanostructures by electron beam irradiation for biocompatibility and electrochemical performance

This paper reports the effect of electron beam irradiation on CuO thin films synthesized by the successive ionic layer adsorption and reaction (SILAR) method on copper foil for supercapacitor and biocompatibility application. Pristine and irradiated samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and electrochemical study. Pristine and irradiated CuO films were pure monoclinic phase, with uniform nanostructures over the whole copper foil. After irradiation, CuO samples had formed innovative nanostructures. Biocompatibility of pristine and irradiated CuO samples suggest that CuO sample is non-toxic and ecofriendly. The specific capacitance of pristine and irradiated CuO strongly depends on surface morphology, and CuO electrodes after irradiation showed superior performance than pristine CuO. The highest specific capacitance of the 20kGy irradiated CuO nanoflowers exceeded 511Fg^-1 at 10mVs^-1 in 1M KOH electrolyte. Irradiated CuO samples also showed lower ESR, and were superior to other report electrical energy storage materials.

Helical carbon tubes derived from epitaxial Cu-MOF coating on textile for enhanced supercapacitor performance

A new helical carbon tube material has been prepared from epitaxial Cu-MOF coating on textile by calcination treatment.

Self-assembled Mn-doped MoS2 hollow nanotubes with significantly enhanced sodium storage for high-performance sodium-ion batteries

Mn-Doped MoS₂ hollow nanotubes as an anode exhibit an enhanced fast sodium ion transport capability and superb electrochemical properties in sodium-ion batteries.

Morphology Control of Carbon-Free Spinel NiCo2O4 Catalysts for Enhanced Bifunctional Oxygen Reduction and Evolution in Alkaline Media

Spinel NiCo₂O₄ is considered a promising precious metal-free catalyst that is also carbon-free for oxygen electrocatalysis. Current efforts mainly focus on optimal chemical doping and substituent to tune its electronic structures for enhanced activity. Here, we study its morphology control and elucidate the morphology-dependent catalyst performance for bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Three types of NiCo₂O₄ catalysts with significantly distinct morphologies were prepared using temple-free, Pluronic-123 (P-123) soft, and SiO₂ hard templates, respectively, via hydrothermal methods followed by calcination. Whereas the hard-template yields spherelike dense structures, soft-template assists the formation of a unique nanoneedle cluster assembly containing abundant meso- and macropores. Furthermore, the effect of morphology of NiCo₂O₄ on their corresponding bifunctional catalytic performance was systematically investigated. The flowerlike nanoneedle assembly NiCo₂O₄ catalyst via the soft-template method exhibited the highest catalytic activity and stability for both ORR and OER. In particular, it exhibited an onset and half-wave potentials of 0.94 and 0.82 V versus reversible hydrogen electrode, respectively, for the ORR in alkaline media. Although it is still inferior to Pt, the NiCo₂O₄ represents one of the best ORR catalyst compared to other reported carbon-free oxides. Meanwhile, remarkable OER activity and stability were achieved with an onset potential of 1.48 V and a current density of 15 mA/cm² at 1.6 V, showing no activity loss after 20 000 potential cycles (0-1.9 V). The demonstrated stability is even superior to Ir for the OER. The morphology-controlled approach provides an effective solution to create a robust three-dimensional architecture with increased surface areas and enhanced mass transfer. Importantly, the soft template can yield a high degree of spinel crystallinity with ideal stoichiometric ratios between Ni and Co, thus promoting structural integrity with enhanced electrical conductivity and catalytic properties.

Tuning the morphologies of fluorine-doped tin oxides in the three-dimensional architecture of graphene for high-performance lithium-ion batteries

The morphology of electrode materials plays an important role in determining the performance of lithium-ion batteries (LIBs). However, studies on determining the most favorable morphology for high-performance LIBs have rarely been reported. In this study, a series of F-doped SnO _x (F-SnO₂ and F-SnO) materials with various morphologies was synthesized using ethylenediamine as a structure-directing agent in a facile hydrothermal process. During the hydrothermal process, the F-SnO _x was embedded in situ into the three-dimensional (3D) architecture of reduced graphene oxide (RGO) to form F-SnO _x @RGO composites. The morphologies and nanostructures of F-SnO _x , i.e., F-SnO₂ nanocrystals, F-SnO nanosheets, and F-SnO₂ aggregated particles, were fully characterized using electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. Electrochemical characterization indicated that the F-SnO₂ nanocrystals uniformly distributed in the 3D RGO architecture exhibited higher specific capacity, better rate performance, and longer cycling stability than the F-SnO _x with other morphologies. These excellent electrochemical performances were attributed to the uniform distribution of the F-SnO₂ nanocrystals, which significantly alleviated the volume changes of the electrode material and shortened the Li ion diffusion path during lithiation/delithiation processes. The F-SnO₂@RGO composite composed of uniformly distributed F-SnO₂ nanocrystals also exhibited excellent rate performance, as the specific capacities were measured to be 1158 and 648 mA h g^-1 at current densities of 0.1 and 5 A g^-1, respectively.

Supramolecular hydrogel directed self-assembly of C- and N-doped hollow CuO as high-performance anode materials for Li-ion batteries

In situreduction of Cu²⁺and hydrogel-directed self-assembly into a hollow Cu/Cu₂O nanocomposites with homogeneous C, N doping.

Role of compensating Li/Fe incorporation in Cu0.945Fe0.055−xLixO: structural, vibrational and magnetic properties

Monoclinic single phase Cu_0.945Fe_0.055−xLi_xO, with Cu²⁺ properly substituted by Fe³⁺ and Li¹⁺, shows enhanced magnetic moment with stronger FM coupling due to Li¹⁺ doping.

Freestanding three-dimensional core-shell nanoarrays for lithium-ion battery anodes

Structural degradation and low conductivity of transition-metal oxides lead to severe capacity fading in lithium-ion batteries. Recent efforts to solve this issue have mainly focused on using nanocomposites or hybrids by integrating nanosized metal oxides with conducting additives. Here we design specific hierarchical structures and demonstrate their use in flexible, large-area anode assemblies. Fabrication of these anodes is achieved via oxidative growth of copper oxide nanowires onto copper substrates followed by radio-frequency sputtering of carbon-nitride films, forming freestanding three-dimensional arrays with core–shell nano-architecture. Cable-like copper oxide/carbon-nitride core–shell nanostructures accommodate the volume change during lithiation−delithiation processes, the three-dimensional arrays provide abundant electroactive zones and electron/ion transport paths, and the monolithic sandwich-type configuration without additional binders or conductive agents improves energy/power densities of the whole electrode.

Degradation and low conductivity of transition metal oxide anodes cause capacity fading in lithium ion batteries. Here the authors make freestanding 3D copper oxide/carbon nitride core-shell nanoarrays which accommodate volume change, provide electro-active zones and facilitate rapid charge transport.

Advanced Mesoporous Spinel Li4Ti5O12/rGO Composites with Increased Surface Lithium Storage Capability for High-Power Lithium-Ion Batteries

Spinel Li4Ti5O12 (LTO) and reduced graphene oxide (rGO) are attractive anode materials for lithium-ion batteries (LIBs) because of their unique electrochemical properties. Herein, we report a facile one-step hydrothermal method in preparation of a nanocomposite anode consisting of well-dispersed mesoporous LTO particles onto rGO. An important reaction step involves glucose as a novel linker agent and reducing agent during the synthesis. It was found to prevent the aggregation of LTO particles, and to yield mesoporous structures in nanocomposites. Moreover, GO is reduced to rGO by the hydroxyl groups on glucose during the hydrothermal process. When compared to previously reported LTO/graphene electrodes, the newly prepared LTO/rGO nanocomposite has mesoporous characteristics and provides additional surface lithium storage capability, superior to traditional LTO-based materials for LIBs. These unique properties lead to markedly improved electrochemical performance. In particular, the nanocomposite anode delivers an ultrahigh reversible capacity of 193 mA h g(-1) at 0.5 C and superior rate performance capable of retaining a capacity of 168 mA h g(-1) at 30 C between 1.0 and 2.5 V. Therefore, the newly prepared mesoporous LTO/rGO nanocomposite with increased surface lithium storage capability will provide a new opportunity to develop high-power anode materials for LIBs.