A bubble-template approach for assembling Ni–Co oxide hollow microspheres with an enhanced electrochemical performance as an anode for lithium ion batteries

A bubble-template approach was developed to assemble Ni–Co oxide hollow microspheres with an enhanced electrochemical performance as an anode for lithium ion batteries.

Graphene-coated mesoporous Co3O4 fibers as an efficient anode material for Li-ion batteries

The graphene-coating porous cobalt oxide fibers (Co₃O₄@G) were synthesized using coordination polymers as precursors through calcination and subsequent self-assembly process. The obtained materials exhibit good electrochemical performances.

Cobalt oxide nanoparticle embedded N-CNTs: lithium ion battery applications

ZIF-12 is converted to Co/N-CNTs at 950 °C under an argon atmosphere. The obtained hybrid nanocomposite is used for LIBs application as an anode material with superior charge storage performance.

Carbon-Encapsulated Co3O4 Nanoparticles as Anode Materials with Super Lithium Storage Performance

A high-performance anode material for lithium storage was successfully synthesized by glucose as carbon source and cobalt nitrate as Co₃O₄ precursor with the assistance of sodium chloride surface as a template to reduce the carbon sheet thickness. Ultrafine Co₃O₄ nanoparticles were homogeneously embedded in ultrathin porous graphitic carbon in this material. The carbon sheets, which have large specific surface area, high electronic conductivity, and outstanding mechanical flexibility, are very effective to keep the stability of Co₃O₄ nanoparticales which has a large capacity. As a consequence, a very high reversible capacity of up to 1413 mA h g⁻¹ at a current density of 0.1 A g⁻¹ after 100 cycles, a high rate capability (845, 560, 461 and 345 mA h g⁻¹ at 5, 10, 15 and 20 C, respectively, 1 C = 1 A g⁻¹), and a superior cycling performance at an ultrahigh rate (760 mA h g⁻¹ at 5 C after 1000 cycles) are achieved by this lithium-ion-battery anode material.

Layer matching epitaxy of NiO thin films on atomically stepped sapphire (0001) substrates

Thin-film epitaxy is critical for investigating the original properties of materials. To obtain epitaxial films, careful consideration of the external conditions, i.e. single-crystal substrate, temperature, deposition pressure and fabrication method, is significantly important. In particular, selection of the single-crystal substrate is the first step towards fabrication of a high-quality film. Sapphire (single-crystalline α-Al₂O₃) is commonly used in industry as a thin-film crystal-growth substrate, and functional thin-film materials deposited on sapphire substrates have found industrial applications. However, while sapphire is a single crystal, two types of atomic planes exist in accordance with step height. Here we discuss the need to consider the lattice mismatch for each of the sapphire atomic layers. Furthermore, through cross-sectional transmission electron microscopy analysis, we demonstrate the uniepitaxial growth of cubic crystalline thin films on bistepped sapphire (0001) substrates.

Brannerite-Type Vanadium-Molybdenum Oxide LiVMoO₆ as a Promising Anode Material for Lithium-Ion Batteries with High Capacity and Rate Capability

Brannerite-type vanadium-molybdenum oxide LiVMoO6 is prepared by a facile liquid-phase method, and its electrochemical properties as anode of lithium-ion batteries are comprehensively studied by means of galvanostatic charge-discharge profiles, rate performance, and cyclic voltammetry. In the working voltage between 3.0 and 0.01 V, LiVMoO6 delivers a high reversible capacity of more than 900 mAh g(-1) at the current density of 100 mA g(-1) and a superior rate capability with discharge capacity of ca. 584 and 285 mAh g(-1) under the high current densities of 2 and 5 A g(-1), respectively. Moreover, ex situ X-ray diffraction and X-ray photoelectron spectroscopy are utilized to examine the phase evolution and valence changes during the first lithiated process. A small amount of inserted Li(+) induces a decomposition of LiVMoO6 into Li2Mo2O7 and V2O5, which play the host during further lithiated processes. When being discharged to 0.01 V, most V(5+) change into V(3+)/V(2+), suggesting intercalation/deintercalation processes, whereas Mo(6+) are reduced into a metallic state on the basis of the conversion reaction. The insights obtained from this study will benefit the design of novel anode materials for lithium-ion batteries.

TiC/NiO Core/Shell Nanoarchitecture with Battery-Capacitive Synchronous Lithium Storage for High-Performance Lithium-Ion Battery

The further development of electrode materials with high capacity and excellent rate capability presents a great challenge for advanced lithium-ion batteries. Herein, we demonstrate a battery-capacitive synchronous lithium storage mechanism based on a scrupulous design of TiC/NiO core/shell nanoarchitecture, in which the TiC nanowire core exhibits a typical double-layer capacitive behavior, and the NiO nanosheet shell acts as active materials for Li(+) storage. The as-constructed TiC/NiO (32 wt % NiO) core/shell nanoarchitecture offers high overall capacity and excellent cycling ability, retaining above 507.5 mAh g(-1) throughout 60 cycles at a current density of 200 mA g(-1) (much higher than theoretical value of the TiC/NiO composite). Most importantly, the high rate capability is far superior to that of NiO or other metal oxide electrode materials, owing to its double-layer capacitive characteristics of TiC nanowire and intrinsic high electrical conductivity for facile electron transport during Li(+) storage process. Our work offers a promising approach via a rational hybridization of two electrochemical energy storage materials for harvesting high capacity and good rate performance.

Three dimensional metal oxides–graphene composites and their applications in lithium ion batteries

The review focuses on the effects of morphology, composition and interaction of 3d metal oxide–graphene composites on the performances of libs.

Chemically anchored NiOx–carbon composite fibers for Li-ion batteries with long cycle-life and enhanced capacity

NiO_x nanoparticles are chemically anchored on carbon fiber networks to obtain binder-free anodes with high properties for Li⁺ storage.

High performance NiO microsphere anode assembled from porous nanosheets for lithium-ion batteries

3D NiO microspheres assembled from porous nanosheets were fabricated, showing an excellent electrochemical performance in a lithium ion battery (reversible discharge capacity: up to 820 mA h g⁻¹ after 100 cycles at 100 mA g⁻¹; rate capacity: 634 mA h g⁻¹ at 1 A g⁻¹).

Excellent electrochemical performance of NiV3O8/natural graphite anodes via novel in situ electrochemical reconstruction

NiV₃O₈/natural graphite anodes show excellent electrochemical performance via a novel in situ electrochemical reconstruction.

Theoretical simulation of the reduction of graphene oxide by lithium naphthalenide

Based on density functional theory, we investigated the mechanism of graphene oxide reduction by lithium naphthalenide. CO₂ plays an important role in deoxidation of GO.

Improving the anode performances of TiO2–carbon–rGO composites in lithium ion batteries by UV irradiation

A three-dimensional TiO₂–carbon–rGO (TCG) composite was fabricated and post-treated with UV irradiation (254 nm) for 0.5 h to improve the anode performances in LIBs.

Growth of hierarchal mesoporous NiO nanosheets on carbon cloth as binder-free anodes for high-performance flexible lithium-ion batteries

Mesoporous NiO nanosheets were directly grown on three-dimensional (3D) carbon cloth substrate, which can be used as binder-free anode for lithium-ion batteries (LIBs). These mesoporous nanosheets were interconnected with each other and forming a network with interval voids, which give rise to large surface area and efficient buffering of the volume change. The integrated hierarchical electrode maintains all the advantageous features of directly building two-dimensional (2D) nanostructues on 3D conductive substrate, such as short diffusion length, strain relaxation and fast electron transport. As the LIB anode, it presents a high reversible capacity of 892.6 mAh g⁻¹ after 120 cycles at a current density of 100 mA g⁻¹ and 758.1 mAh g⁻¹ at a high charging rate of 700 mA g⁻¹ after 150 cycles. As demonstrated in this work, the hierarchical NiO nanosheets/carbon cloth also shows high flexibility, which can be directly used as the anode to build flexible LIBs. The introduced facile and low-cost method to prepare NiO nanosheets on flexible and conductive carbon cloth substrate is promising for the fabrication of high performance energy storage devices, especially for next-generation wearable electronic devices.

Hierarchical ZnO-Ag-C composite porous microspheres with superior electrochemical properties as anode materials for lithium ion batteries

Hierarchical ZnO-Ag-C composite porous microspheres are successfully synthesized by calcination of the preproduced zinc-silver citrate porous microspheres in argon. The carbon derives from the in situ carbonization of carboxylic acid groups in zinc-silver citrate during annealing treatment. The average particle size of ZnO-Ag-C composite porous microspheres is approximate 1.5 μm. When adopted as the electrode materials in lithium ion batteries, the obtained composite porous microspheres display high specific capacity, excellent cyclability, and good rate capability. A discharge capacity as high as 729 mA h g(-1) can be retained after 200 cycles at 100 mA g(-1). The excellent electrochemical properties of ZnO-Ag-C are ascribed to its unique hierarchical porous configuration as well as the modification of silver and carbon.

Graphene-based nanocomposite anodes for lithium-ion batteries

Graphene-based nanocomposites have been demonstrated to be promising high-capacity anodes for lithium ion batteries to satisfy the ever-growing demands for higher capacity, longer cycle life and better high-rate performance. Synergetic effects between graphene and the introduced second-phase component are generally observed. In this feature review article, we will focus on the recent work on four different categories of graphene-based nanocomposite anodes by us and others: graphene-transitional metal oxide, graphene-Sn/Si/Ge, graphene-metal sulfide, and graphene-carbon nanotubes. For the supported materials on graphene, we will emphasize the non-zero dimensional (non-particle) morphologies such as two dimensional nanosheet/nanoplate and one dimensional nanorod/nanofibre/nanotube morphologies. The synthesis strategies and lithium-ion storage properties of these highlighted electrode morphologies are distinct from those of the commonly obtained zero dimensional nanoparticles. We aim to stress the importance of structure matching in the composites and their morphology-dependent lithium-storage properties and mechanisms.

Rapid continuous synthesis of spherical reduced graphene ball-nickel oxide composite for lithium ion batteries

In this study, we synthesized a powder consisting of core-shell-structured Ni/NiO nanocluster-decorated graphene (Ni/NiO-graphene) by a simple process for use as an anodic material for lithium-ion batteries. First, a crumpled graphene powder consisting of uniformly distributed Ni nanoclusters was prepared by one-pot spray pyrolysis. This powder was subsequently transformed into the Ni/NiO-graphene composite by annealing at 300°C in air. The Ni/NiO-graphene composite powder exhibited better electrochemical properties than those of the hollow-structured NiO-Ni composite and pure NiO powders. The initial discharge and charge capacities of the Ni/NiO-graphene composite powder were 1156 and 845 mA h g⁻¹, respectively, and the corresponding initial coulombic efficiency was 73%. The discharge capacities of the Ni/NiO-graphene, NiO-Ni, and pure NiO powders after 300 cycles were 863, 647, and 439 mA h g⁻¹, respectively. The high stability of the Ni/NiO-graphene composite powder, attributable to the unique structure of its particles, resulted in it exhibiting long-term cycling stability even at a current density of 1500 mA g⁻¹, as well as good rate performance. The structural stability of the Ni/NiO-graphene composite powder particles during cycling lowered the charge transfer resistance and improved the Li-ion diffusion rate.

Engineering single crystalline Mn3O4 nano-octahedra with exposed highly active {011} facets for high performance lithium ion batteries

Well shaped single crystalline Mn3O4 nano-octahedra with exposed highly active {011} facets at different particle sizes have been synthesized and used as anode materials for lithium ion batteries. The electrochemical results show that the smallest sized Mn3O4 nano-octahedra show the best cycling performance with a high initial charge capacity of 907 mA h g(-1) and a 50th charge capacity of 500 mA h g(-1) at a current density of 50 mA g(-1) and the best rate capability with a charge capacity of 350 mA h g(-1) when cycled at 500 mA g(-1). In particular, the nano-octahedra samples demonstrate a much better electrochemical performance in comparison with irregular shaped Mn3O4 nanoparticles. The best electrochemical properties of the smallest Mn3O4 nano-octahedra are ascribed to the lower charge transfer resistance due to the exposed highly active {011} facets, which can facilitate the conversion reaction of Mn3O4 and Li owing to the alternating Mn and O atom layers, resulting in easy formation and decomposition of the amorphous Li2O and the multi-electron reaction. On the other hand, the best electrochemical properties of the smallest Mn3O4 nano-octahedra can also be attributed to the smallest size resulting in the highest specific surface area, which provides maximum contact with the electrolyte and facilitates the rapid Li-ion diffusion at the electrode/electrolyte interface and fast lithium-ion transportation within the particles. The synergy of the exposed {011} facets and the smallest size (and/or the highest surface area) led to the best performance for the Mn3O4 nano-octahedra. Furthermore, HRTEM observations verify the oxidation of MnO to Mn3O4 during the charging process and confirm that the Mn3O4 octahedral structure can still be partly maintained after 50 discharge-charge cycles. The high Li-ion storage capacity and excellent cycling performance suggest that Mn3O4 nano-octahedra with exposed highly active {011} facets could be excellent anode materials for high-performance lithium-ion batteries.

Hierarchical 3D TiO2@Fe2O3 nanoframework arrays as high-performance anode materials

Hierarchical 3D TiO2@Fe2O3 nanoframework arrays grown on a Ti substrate are synthesized via a facile hydrothermal reaction. As the synergetic effect of this hybrid material, the TiO2@Fe2O3 electrode shows superior rate capability and cycling performance to bare TiO2 and Fe2O3 electrodes.

Ideal three-dimensional electrode structures for electrochemical energy storage

Three-dimensional electrodes offer great advantages, such as enhanced ion and electron transport, increased material loading per unit substrate area, and improved mechanical stability upon repeated charge-discharge. The origin of these advantages is discussed and the criteria for ideal 3D electrode structure are outlined. One of the common features of ideal 3D electrodes is the use of a 3D carbon- or metal-based porous framework as the structural backbone and current collector. The synthesis methods of these 3D frameworks and their composites with redox-active materials are summarized, including transition metal oxides and conducting polymers. The structural characteristics and electrochemical performances are also reviewed. Synthesis of composite 3D electrodes is divided into two types - template-assisted and template-free methods - depending on whether a pre-made template is required. The advantages and drawbacks of both strategies are discussed.

Porous graphene materials for advanced electrochemical energy storage and conversion devices

Combining the advantages from both porous materials and graphene, porous graphene materials have attracted vast interests due to their large surface areas, unique porous structures, diversified compositions and excellent electronic conductivity. These unordinary features enable porous graphene materials to serve as key components in high-performance electrochemical energy storage and conversion devices such as lithium ion batteries, supercapacitors, and fuel cells. This progress report summarizes the typical fabrication methods for porous graphene materials with micro-, meso-, and macro-porous structures. The structure-property relationships of these materials and their application in advanced electrochemical devices are also discussed.

Facile synthesis of Co3O4 porous nanosheets/reduced graphene oxide composites and their excellent supercapacitor performance

Porous Co₃O₄ nanosheets/RGO composite with excellent capacitive performance was prepared through a facile two-step strategy.

The binder effect on an oxide-based anode in lithium and sodium-ion battery applications: the fastest way to ultrahigh performance

A positive effect of the polyacrylic acid–carboxymethyl cellulose binder to enhance the performance of an oxide-based anode was reported in batteries.

CoFe2O4-Graphene Nanocomposites Synthesized through An Ultrasonic Method with Enhanced Performances as Anode Materials for Li-ion Batteries

CoFe₂O₄-graphene nanocomposites (CoFe₂O₄-GNSs) have been synthesized through an ultrasonic method combined with calcination process. The nanocomposite calcinated at 350 °C shows better rate capabilities, e.g., 696, 495, 308, and 254 mAh g^-1 at 1, 2, 5, and 10 A g^-1, respectively.

Structurally tailored graphene nanosheets as lithium ion battery anodes: an insight to yield exceptionally high lithium storage performance

How to tune graphene nanosheets (GNSs) with various morphologies has been a significant challenge for lithium ion batteries (LIBs). In this study, three types of GNSs with varying size, edge sites, defects and layer numbers have been successfully achieved. It was demonstrated that controlling GNS morphology and microstructure has important effects on its cyclic performance and rate capability in LIBs. Diminished GNS layer number, decreased size, increased edge sites and increased defects in the GNS anode can be highly beneficial to lithium storage and result in increased electrochemical performance. Interestingly, GNSs treated with a hydrothermal approach delivered a high reversible discharge capacity of 1348 mA h g(-1). This study demonstrates that the controlled design of high performance GNS anodes is an important concept in LIB applications.

Preparation via an electrochemical method of graphene films coated on both sides with NiO nanoparticles for use as high-performance lithium ion anodes

We report on a simple strategy for the direct synthesis of a thin film comprising interconnected NiO nanoparticles deposited on both sides of a graphene sheet via cathodic deposition. For the co-electrodeposition, graphene oxide (GO) is treated with water-soluble cationic poly(ethyleneimine) (PEI) which acts as a stabilizer and trapping agent to form complexes of GO and Ni2+. The positively charged complexes migrate toward the stainless steel substrate, resulting in the electrochemical deposition of PEI-modified GO/Ni(OH)2 at the electrode surface under an applied electric field. The as-synthesized film is then converted to graphene/NiO after annealing at 350 ° C. The interconnected NiO nanoparticles are uniformly deposited on both sides of the graphene surface, as evidenced by field emission scanning electron microscopy, transmission electron microscopy and energy dispersive spectrometry. This graphene/NiO structure shows enhanced electrochemical performance with a large reversible capacity, good cyclic performance and improved electronic conductivity as an anode material for lithium ion batteries. A reversible capacity is retained above 586 mA h g−1 after 50 cycles. The findings reported herein suggest that this strategy can be effectively used to overcome a bottleneck problem associated with the electrochemical production of graphene/metal oxide films for lithium ion battery anodes.

Ultrathin calcium silicate hydrate nanosheets with large specific surface areas: synthesis, crystallization, layered self-assembly and applications as excellent adsorbents for drug, protein, and metal ions

A simple and low-cost solution synthesis is reported for low-crystalline 1.4 nm tobermorite-like calcium silicate hydrate (CSH) ultrathin nanosheets with a thickness of ~2.8 nm and with a large specific surface area (SSA), via a reaction-rate-controlled precipitation process. The BET SSA of the CSH ultrathin nanosheets can reach as high as 505 m(2) g(-1) . The CSH ultrathin nanosheets have little cytotoxicity and can be converted to anhydrous calcium silicate (ACS) ultrathin nanosheets with a well preserved morphology via a heat treatment process. The crystallinity of CSH ultrathin nanosheets can be improved by solvothermal treatment in water/ethanol binary solvents or a single solvent of water, producing well-crystalline 1.1 nm tobermorite-like CSH nanobelts or nanosheets. CSH ultrathin nanosheets acting as building blocks can self-assemble into layered nanostructures via three different routes. The CSH ultrathin nanosheets are investigated as promising adsorbents for protein (hemoglobin, Hb), drug (ibuprofen, IBU), and metal ions (Cr(3+) , Ni(2+) , Cu(2+) , Zn(2+) , Cd(2+) , Pb(2+) ). The highest adsorbed percentages of Hb and IBU are found to be 83% and 94%, respectively. The highest adsorption capacities of Hb and IBU are found to be as high as 878 milligram Hb per gram CSH and 2.2 gram IBU per gram CSH, respectively. The ppm level metal ions can be totally adsorbed from aqueous solution in just a few minutes. Thus, the CSH ultrathin nanosheets are a promising candidate as excellent adsorbents in the biomedical field and for waste water treatment. Several empirical laws are summarized based on the adsorption profiles of Hb and IBU using CSH ultrathin nanosheets as the adsorbent. Furthermore, the ACS ultrathin nanosheets as adsorbents for Hb protein and IBU drug are investigated.

MnFe2O4-graphene nanocomposites with enhanced performances as anode materials for Li-ion batteries

MnFe(2)O(4)-graphene nanocomposites (MnFe(2)O(4)-GNSs) with enhanced electrochemical performances have been successfully prepared through an ultrasonic method, e.g., approximate 1017 mA h g(-1) and 767 mA h g(-1) reversible capacities are retained even after 90 cycles at a current density of 0.1 A g(-1) and 1 A g(-1), respectively. The remarkable improvement in the reversible capacity, cyclic stability and rate capability of the obtained MnFe(2)O(4)-GNSs nanocomposites can be attributed to the good electrical conductivity and special structure of the graphene nanosheets. On the other hand, MnFe(2)O(4) also plays an important role because it transforms into a nanosized hybrid of Fe(3)O(4)-MnO with a particle size of about 20 nm during discharge-charge process, and the in situ formed hybrid of Fe(3)O(4)-MnO can be combined with GNSs to form a spongy porous structure. Furthermore, the formed hybrid can also act as the matrix of MnO or Fe(3)O(4) to prevent the aggregation of Fe(3)O(4) or MnO, and accommodate the volume change of the active materials during the discharge-charge processes, which is also beneficial to improve the electrochemical performances of the MnFe(2)O(4)-GNSs nanocomposites.

Trace amounts of water-induced distinct growth behaviors of NiO nanostructures on graphene in CO2-expanded ethanol and their applications in lithium-ion batteries

In this work, we have developed a new method to grow NiO nanomaterials on the surface of graphene nanosheets (GNSs). The morphologies of NiO nanomaterials grown on GNSs could be tailored by trace amounts of water introduced into the mixed solvents of CO2-expanded ethanol (CE). Small and uniform Ni-salt nanoparticles (Ni-salt-NPs) were grown on the surface of graphene oxide (GO) through the decomposition of nickel nitrate directly in CE. However, when trace amounts of water were introduced into the mixed solvents, Ni-salt nanoflakes arrays (Ni-salt-NFAs) were grown on the surface of GO with almost perpendicular direction. After thermal treatment in N2 atmosphere, these Ni-salt @GO composites were converted to NiO@GNSs composites. The forming mechanisms of the NiO-NPs@GNSs and NiO-NFAs@GNSs were discussed by series comparative experiments. The presence of the trace amounts of water affected the chemical composition and structure of the precursors formed in CE and the growth behaviors on the surface of GNSs. When used as anode materials for lithium-ion batteries, the NiO-NPs@GNSs composite exhibited better cycle and rate performance compared with the NiO-NFAs@GNSs.

Scalable synthesis of urchin- and flowerlike hierarchical NiO microspheres and their electrochemical property for lithium storage

A nickel salt-urea-H2O ternary system has been developed for the large-scale synthesis of hierarchical α-Ni(OH)2 microspheres, the solid precursor for the subsequent topotactic transition to NiO upon calcination. In this facile synthetic system, hierarchical structure is self-assembled under the cooperative direction of urea and anions in nickel salts. Thus, simply tuning the Ni salts leads to the selective construction of urchin and flowerlike hierarchical α-Ni(OH)2 and NiO microspheres consisting of radial 1D nanowires and 2D nanoplates, respectively. The obtained NiO microspheres possessing accessible nanopores, excellent structural stability and large surface area up to 130 m(2)/g show promising electrochemical performance in anodic lithium storage for lithium-ion battery.

Reduced graphene oxide wrapped FeS nanocomposite for lithium-ion battery anode with improved performance

A new nanocomposite formulation of the FeS-based anode for lithium-ion batteries is proposed, where FeS nanoparticles wrapped in reduced graphene oxide (RGO) are produced via a facile direct-precipitation approach. The resulting nanocomposite FeS@RGO structure has better lithium ion storage properties, exceeding those of FeS prepared without RGO sheets. The enhanced electrochemical performance is attributed to the robust sheet-wrapped structure with smaller FeS nanoparticles and synergetic effects between FeS and RGO sheets, such as increased conductivity, shortened lithium ion diffusion path, and the effective prevention of polysulfide dissolution.