Porous Co3O4 column as a high-performance Lithium anode material

Journal of Porous Materials - Co3O4 has been widely investigated as a promising candidate anode material for lithium-ion batteries. We report on the porous Co3O4 column synthesized via a simple...     

Layer-by-layer assembled MoO₂-graphene thin film as a high-capacity and binder-free anode for lithium-ion batteries

Thin films of MoO(2) nanoparticles and graphene sheets are created by layer-by-layer (LBL) assembly as binder-free anodes for lithium-ion batteries. Both anionic polyoxometalate clusters and graphene oxide nanosheets with oxygen functional groups on both basal planes and edges are assembled into LBL films with the aid of a cationic polyelectrolyte. After a subsequent thermal treatment in an Ar-H(2) atmosphere, hybrid MoO(2)-graphene films with three-dimensionally interconnected nanopores are formed, which comprise ultrafine MoO(2) nanoparticles homogeneously embedded in the porous network of graphene nanosheets. When used as an anode for lithium-ion batteries, the MoO(2)-graphene thin-film electrode shows superior electrochemical performance with high specific capacity and excellent cyclability. A high specific capacity of 675.9 mA h g(-1) after 100 discharge-charge cycles is achieved, indicating a promising anode candidate for lithium-storage applications.     

Porous graphene networks as high performance anode materials for lithium ion batteries

Porous graphene obtained by chemical vapor deposition (CVD) using porous MgO sheets as template is demonstrated to exhibit a high reversible capacity (1723 mAh g^-1), excellent high-rate capability and cycling stability for Li-ion batteries. The simple CVD approach offers a new way for large-scale production of porous graphene materials for energy storage.     

A facile approach toward transition metal oxide hierarchical structures and their lithium storage properties

A simple, non-template, non-surfactant and environmentally friendly hydrothermal method is presented based on the controlled release of the reactants into the reaction solvents to induce slow nucleation and growth of three-dimensional hierarchical nanostructures of transition metal oxides. This method is a general approach, which can be used to prepare Co(3)O(4), CuO, and Ni(OH)(2)/NiO. These metal oxides with hierarchical nanostructures can be used as anode materials for lithium-ion batteries with good Li storage performance, e.g. high specific capacities and stable cyclability.     

Reduced graphene oxide supported highly porous V2O5 spheres as a high-power cathode material for lithium ion batteries

Reduced graphene oxide (rGO) supported highly porous polycrystalline V(2)O(5) spheres (V(2)O(5)/rGO) were prepared by using a solvothermal approach followed by an annealing process. Initially, reduced vanadium oxide (rVO) nanoparticles with sizes in the range of 10-50 nm were formed through heterogeneous nucleation on rGO sheets during the solvothermal process. These rVO nanoparticles were oxidized to V(2)O(5) after the annealing process in air at 350 °C and assembled into polycrystalline porous spheres with sizes of 200-800 nm. The weight ratio between the rGO and V(2)O(5) is tunable by changing the weight ratio of the precursors, which in turn affects the morphology of V(2)O(5)/rGO composites. The V(2)O(5)/rGO composites display superior cathode performances with highly reversible specific capacities, good cycling stabilities and excellent rate capabilities (e.g. 102 mA h g(-1) at 19 C).     

Aqueous solution synthesis of reduced graphene oxide-germanium nanoparticles and their electrical property testing

Aqueous solution synthesis of reduced graphene oxide-germanium nanoparticles (RGO-GeNPs) was developed using graphene oxide (GO) as stabilizer, which could be conducive to obtain better excellent electrical properties. The information about morphology and chemical composition of the nanomaterials were obtained by TEM, FTIR, EDS, and XRD measurements. Stable aqueous dispersibility of RGO-GeNPs was further improved by poly(sodium 4-styrenesulfonate) (PSS) to obtain amphiphilic polymer-coated RGO-GeNPs (PSS-RGO-GeNPs). A possible mechanism to interpret the formation of RGO-GeNPs was proposed. The as-synthesized RGO-GeNPs showed excellent battery performance when used as an anode material for Li ion batteries. The resulting nanocomposites exhibited high specific capacity and good cycling stability after 80 cycles. This study showed a facile strategy to synthetize graphene and Ge nanocomposites which can be a hopeful anode material with excellent electrical properties for lithium ion batteries.     

Preparation of graphene supported porous Si@C ternary composites and their electrochemical performance as high capacity anode materials for Li-ion batteries

Graphene supported porous Si@C ternary composites had been synthesized by various routes and their structural, morphological and electrochemical properties were investigated. Porous Si spheres coated with carbon layer and supported by graphene have been designed to form a 3D carbon conductive network. Used as anode materials for lithium ion batteries, graphene supported porous Si@C ternary composites demonstrate excellent electrochemical performance and cycling stability. The first discharge capacity is 2184.7 mA h/g at a high current density of 300 mA/g. After 50 cycles, the reversible capacity is 652.4 mA h/g at a current density of 300 mA/g and the coulomb efficiency reaches at 98.7%. Due to their excellent electrochemical properties, graphene supported porous Si@C ternary composites can be a kind of promising anode materials for lithium ion batteries.     

Facile solvothermal synthesis of mesoporous Cu₂SnS₃ spheres and their application in lithium-ion batteries

Three dimensional (3D) mesoporous Cu(2)SnS(3) spheres composed of nanoparticles were synthesized by a simple solvothermal route. As anode materials for lithium-ion batteries, they delivered remarkably enhanced cycling performances. This could be attributed to the 3D mesoporous structure which may be propitious to the accommodation of volume expansion. Besides, a possible electrochemical reaction mechanism was proposed based on cyclic voltammetry (CV) testing results and confirmed by subsequent ex situ XRD studies. In addition, the influence of testing temperature on cycling performance has also been investigated.     

Preparation of Three-Dimensional Co3O4/graphene Composite for High-Performance Supercapacitors

Here, we developed a simple and efficient route for the preparation of three-dimensional (3D) Co₃O₄-anchored graphene composites using the sacrificial template-assisted method and the subsequent deposition process of Co₃O₄ nanoparticles. As structural guiding materials, polystyrene (PS) spheres provide 3D porous architectures with a high surface area. 3D porous graphene materials serve as conductive supporters for the deposition of Co₃O₄ nanoparticles through precipitation growth. The 3D porous composite structures of Co₃O₄/graphene composites were intensively investigated using scanning electron microscope, transmission electron microscope, and X-ray diffraction. The 3D Co₃O₄/graphene composites show a high specific capacitance of 328?F?g^?1 with efficient and fast charge–discharge process in aqueous 6?M KOH electrolyte. In addition, the composites provide a good cycle lifetime, which retained 98% capacitance retention over 2000 cycles.     

Vertically ordered Ni(3)Si(2)/Si nanorod arrays as anode materials for high-performance Li-ion batteries

In this paper, we have reported a novel hierarchical nanostructure made of vertically ordered Ni(3)Si(2)/Si nanorod arrays to moderate the notorious pulverization and capacity decay usually occurring in the silicon used as the anode materials in Li-ion batteries. During the lithiation and delithiation process, the amorphous Si (a-Si) layer acts as an active material and participates in the processes, whereas the Ni(3)Si(2) nanorod arrays work as a mechanically stable supporter and fast charge transport pathway. In addition, they can afford sufficient interspace for expansion/contraction upon lithium insertion/extraction. These Ni(3)Si(2)/Si nanorod arrays anodes exhibit excellent cycling performance at high current rates of 1 C (4.2 A g(-1)), 2 C (8.4 A g(-1)), and 4 C (16.8 A g(-1)), respectively. A high and steady discharge capacity of over 2184 mA h g(-1) can be achieved after 50 cycles with a high initial coulombic efficiency of 86.7%. The synthesis approach is simple, efficient and rich-yielding, probably providing a new strategy for the application of silicon-based anode materials with enhanced performance.     

Controllable synthesis of monodisperse ultrathin SnO(2) nanorods on nitrogen-doped graphene and its ultrahigh lithium storage properties

Monodisperse ultrathin SnO(2) nanorods on nitrogen-doped graphene were firstly synthesized by a facile one-step hydrothermal strategy. The uniformed composites with high nitrogen content and ultrathin SnO(2) nanorods of 2.5-4.0 nm in diameter and 10-15 nm in length show a high reversible specific capacity, superior rate capability and outstanding cycling stability (803 mA h g(-1)) as anode materials for lithium ion batteries, owing to the synergistic effect between GS and SnO(2) and nitrogen-doping, which can greatly decrease the energy barrier for Li penetrating the pyridinic defects and improve the electronic structures. This work opens the door to prepare metal oxide/GS-N composites with superior lithium storage properties and engineering of graphene composites for advanced energy storage.     

Electrochemically exfoliated graphene oxide/iron oxide composite foams for lithium storage,produced by simultaneous graphene reduction and Fe(OH)3 condensation

We describe the production of graphene-based composites for energy storage, obtained by a combination of electrochemical and solution processing techniques. Electrochemically exfoliated graphene oxide sheets (EGO) are produced using an original setup that allows fast expansion of graphite flakes and efficient exfoliation of expanded graphite via an electrochemical route. The sheets are deposited on a sacrificial nickel foam together with an iron hydroxide colloidal precursor. Calcination treatment simultaneously renders the EGO foam conductive and transforms Fe(OH)₃ into hematite (α-Fe₂O₃), yielding a nanoporous Fe₂O₃ layer on the surface of the mesoporous EGO foam, creating an ideal structure for lithium storage. The obtained graphene/metal oxide hybrid is a continuous, electrically conductive three-dimensional (3D) composite featuring a hierarchical meso–nano porous structure. A systematic study of these composites, varying the Fe₂O₃:EGO ratio, is then performed to maximize their performance as nanostructured electrodes in standard coin cell batteries.     

(010) facets dominated LiFePO4 nano-flakes confined in 3D porous graphene network as a high-performance Li-ion battery cathode

Olivine-structured LiFePO₄ (LFP) has been widely considered as one of the most promising and safest high-power positive electrode materials for lithium-ion batteries (LIBs) as a power source in the electric transportation. However, the electrochemical behavior of LFP for lithium-storage is seriously restrained by its intrinsic feature of low electrical conductivity and poor lithium-ion diffusion ability. In this research, LFP nano-flakes with oriented (010) facets were prepared through the solvothermal method, and 3D porous composite of LFP nano-flakes confined on graphene (LFP@G) was synthesized by freeze-drying concentrated graphene-oxide-gel containing LFP nano-flakes followed by a heat-treatment process. As the cathode materials for LIBs, LFP@G composite can release a reversible specific capacity of 129 mAh g^?1 at a high current rate of 20?C. Meanwhile, a long cycling stability for LFP@G composite with a capacity of 139.8 mAh g^?1 over 600 cycles up to 10?C can be achieved. The superior electrochemical Li-storage properties of LFP@G composite can be ascribed to the fast lithium-ion transfer channels of LFP originated from the exposed (010) planes, shortened lithium-ion diffusion distance, and the excellent two-phase electric contact between LFP and graphene in the 3D porous graphene conductive network for fast electron and lithium-ion transport.     

Porous CoTiO3 microbars as super rate and long life anodes for sodium ion batteries

Porous CoTiO₃ microbars have been successfully prepared by a facile solution way followed by thermal annealing in air. When evaluated as electrode materials for sodium ion batteries, unique 1D porous structure demonstrates remarkable sodium storage properties. The resultant CoTiO₃ microbar electrodes exhibit not only higher discharge capacity (135.5?mA?h?g^?1 at 300?mA?g^?1 after 500 cycles), but also more enhanced rate performance compared to those of CoTiO₃ microparticle electrodes. The new findings reported here highlight the possibility for designing high-performance anode materials for sodium ion batteries.     

Enhanced electrochemical performance of ion-beam-treated 3D graphene aerogels for lithium ion batteries

High energy light-ion (3.8 MeV He) bombardment is used to introduce lattice defects in a 3-dimensional (3D) interconnected network of graphene aerogels (GAs). When these materials are used as anodes for lithium ion batteries, we observe improved percentage reversible capacity and cycle stability compared to those without ion-beam treatment. Furthermore, all ion-beam treated 3D graphene samples exhibit substantially higher Coulombic efficiencies, suggesting at beneficial role of vacancy-type defects in stabilizing solid-electrolyte interphases. Although 3D graphene exhibits initial reversible capacities that are 2–3 times higher than that of graphite (∼372 mAh/g), fast capacity fading is observed but becomes more stable after ion-beam treatment. Our experimental results demonstrate that ion-beam treatment is an effective route to tune and produce good-performance graphene electrodes, and that vacancy-type defects help to promote reversible lithium storage capacity in graphene. We further observe that 3D GAs irradiated to the highest dose studied (10¹⁶ cm⁻²) fail rapidly upon electrochemical cycling, likely caused by the excessive ion-beam damage and graphene restacking. Raman I(D)/I(D′) signature is considered linked to defect type in graphene and thus is proposed, for the first time, as an indicator of the reversible capacity for GAs.     

Facile precipitation of tin oxide nanoparticles on graphene sheet by liquid phase plasma method for enhanced electrochemical properties

A high-performance lithium ion battery (LIB) electrode was prepared by precipitating tin oxide nanoparticles on graphene powder by the liquid phase plasma (LPP) method. The particles generated by the LPP reaction are spherical SnO₂ nanoparticles with a size of 5-10 nm, as confirmed by a variety of analytical devices. The quantity of SnO₂ nanoparticles partially aggregated on the graphene sheet surface increases as the initial concentration of the tin precursor increases. The SnO₂/graphene nanocomposites (SGNC) electrodes prepared by the LPP method demonstrated improved cycling stability and reversible lithium storage capacity as compared to the bare graphene electrode. The precipitated tin oxide improves the lithium storage capacity, but excess tin oxide nanoparticles rather reduced the cycling stability.     

Controlling the Structural and Dielectric Characteristics of PS-PC/Co2O3-SiC Hybrid Nanocomposites for Nanoelectronics Applications

Silicon - This paper aims to fabricate of polystyrene(PS)-polycarbonate(PC)/Cobalt oxide(III) nanoparticles (Co2O3 NPs)-Silicon carbide nanoparticles (SiC NPs) nanocomposites films to use in...     

In-situ synthesis of reduced graphene oxide wrapped Mn3O4 nanocomposite as anode materials for high-performance lithium-ion batteries

We report a novel in-situ symbiosis method to prepare reduced graphene oxide wrapped Mn₃O₄ nanoparticles (rGO/Mn₃O₄) with uniform size about 50 nm as anodes for lithium-ion batteries (LIBs), which can simplify the preparation process and effectively reduce pollution. The rGO/Mn₃O₄ nanocomposite exhibited a reversible specific capacity of 795.5 mAh g^?1 at 100 mA g^?1 after 200 cycles (capacity retention: 87.4%), which benefits from the unique structural advantages and the synergistic effect of rGO and Mn₃O₄. The Mn₃O₄ nanoparticles encapsulated among the rGO nanosheets exhibited good electrochemical activity, and the multilayer wrinkled rGO sheets provided a stable 3D conduction channel for Li⁺/e^? transport. The rGO/Mn₃O₄ nanocomposite is a promising anode candidate for advanced LIBs with excellent cycling performance and rate performance. Furthermore, this new preparation method can be extended to green and economical synthesis of advanced graphene/manganese-based nanocomposites.     

Monolithic carbons with spheroidal and hierarchical pores produced by the linkage of functionalized graphene sheets

We report a novel monolithic porous carbon constructed by the hydrothermal self-assembly of graphene oxide sheets with poly (vinyl alcohol) as the linker in the formation process of a three-dimensional (3D) structure. All the pores in this carbon have circular cross-sections and range from micropores to mesopores to macropores and are formed by the gradual removal of trapped water. This 3D graphene network together with unique spheroidal and hierarchical pore structure with macropore openings at the surface allows fast ion and electron transport into the innermost micropores. The carbon not only exhibits excellent capability for removal of dye pollutants and oils but also shows a good performance as an electrode material in lithium ion batteries. Moreover, it is also proved to be an ideal buffer for expanded active materials in electrochemical energy storage.     

Facile synthesis of metal oxide/reduced graphene oxide hybrids with high lithium storage capacity and stable cyclability

We report an environment-friendly approach to synthesize transition metal oxide nanoparticles (NPs)/reduced graphene oxide (rGO) sheets hybrids by combining the reduction of graphene oxide (GO) with the growth of metal oxide NPs in one step. Either Fe2O3 or CoO NPs were grown onto rGO sheets in ethanol solution through a solvothermal process, during which GOs were reduced to rGO without the addition of any strong reducing agent, e.g. hydrazine, or requiring any post-high-temperature annealing process. The GO or rGO during the precipitation of metal oxide NPs may act as heterogeneous nucleation seeds to facilitate the formation of small crystal grains. This may allow more efficient diffusion of Li ions and lead to high specific capacities. These metal oxide NPs-rGO hybrids were used as anodes for Li-ion batteries, which showed high capacities and excellent charge-discharge cycling stability in the voltage window between 0.01 and 3.0 V. For example, Fe2O3 NPs/rGO hybrids showed specific capacity of 881 mA h g(-1) in the 90th cycle at a discharge current density of 302 mA g(-1) (0.3 C), while CoO NPs/rGO hybrids showed a lower capacity of 600 mA h g(-1) in the 90th cycle at a discharge current density of 215 mA g(-1) (0.3 C). These nanohybrids also show excellent capacities at high C rate currents, e.g. 611 mA h g(-1) for Fe2O3/rGO sample in the 300th cycle at 2014 mA g(-1) (2 C). Such synthesis technique can be a promising route to produce advanced electrode materials for Li-ion batteries.