Binder-free Anode Material Research Articles

GeOx ultra-dispersed in microporous carbon nanofibers: a binder-free anode for high performance lithium-ion battery

Carbonaceous materials are usually used to improve the electrochemical performance of GeOx for lithium-ion batteries (LIBs). Preparing a material in which GeOx is ultra-dispersed in carbon nanofibers via a simple process has rarely been reported. Here we design and prepare a three-dimensional (3D) composite in which amorphous GeOx is ultra-uniformly distributed in one-dimensional (1D) microporous carbon nanofibers (GeOx-mCNFs) via high energy ball milling combined with carbonization-amorphization reactions. When directly used as a binder-free anode material for LIBs, the as-synthesized GeOx-mCNFs hybrid shows a highly reversible specific capacity, a good rate performance, and an excellent cycling stability (i.e., 621mAhg−1 at 1.2Ag−1 after 300 cycles), which is attributed to the synergistic effects of the ultra-uniform amorphous GeOx, a 1D interconnected carbon nanostructure, and micropores. It is expected that the GeOx-mCNFs hybrid could be utilized as a binder-free anode material in high-current rechargeable lithium-ion batteries.

Hierarchical self-supported C@TiO2-MoS2 core-shell nanofiber mats as flexible anode for advanced lithium ion batteries

The requirements of high power density, excellent cycling ability, flexibility and low cost, are of paramount importance and critical to develop flexible lithium ion batteries (LIBs) for wearable instruments. Here we reported the rational design and fabrication of a flexible self-supported lithium ion anode material, which consists of thin MoS2 nanosheets grown on the surfaces of carbon@TiO2 core-shell nanofibers. The resulting hierarchical ternary nanocomposites exhibited high reversible specific capacity (∼1460mAhg−1 at 100mAg−1), excellent cyclability (little capacity loss even after 1000 cycles) and rate performance (928mAhg−1 at 2Ag−1) as anode in LIB. Furthermore, the binder-free anode material demonstrated new opportunities for flexible lithium ion batteries. The superior lithium storage performance is derived from the present well-designed hierarchical nanofiber structure and the synergic effect of different components and numerous interfaces.

Electrospinning ZnO/carbon nanofiber as binder-free and self-supported anode for Li-ion batteries

For the preparation of higher performance Li-ion batteries, we fabricated a binder-free and self-supported hybrid nanofiber composed of ZnO nanoparticle-decorated core/shell carbon nanofibers (CNFs) by single-nozzle electrospinning of polyvinylpyrrolidone, polyacrylonitrile and zinc acetate dihydrate. After calcination, the hybrid nanofiber can directly serve as binder-free and self-supported anode for Li-ion batteries, which exhibits high capability (723 mA h g−1 at 100 mA g−1) and good cycling stability. The CNFs in crisscross structure with good conductivity and strength ensure the fast transportation of electrons and Li ions. In addition, the ca. 2.0 nm amorphous carbon layers on the surface of ZnO nanoparticles can suppress the volume expansion of ZnO in the insertion/extraction of Li ions and improve the cycling stability of ZnO/CNFs, while do not inhibit the transportation of Li ions. These encouraging results suggest a simple and effective method to obtain binder-free and self-supported anode material for Li-ion batteries.

CuO Nanorod Arrays Formed Directly on Cu Foil from MOFs as Superior Binder-Free Anode Material for Lithium-Ion Batteries

In this study, an in situ growth method is developed for the partial conversion of current collector into active materials for lithium ion batteries (LIBs). Through thermal treatment of a metal–organic framework (MOF) precursor, of which the metal ion is provided by a Cu foil current collector, porous CuO nanorod arrays (NRAs) can be directly formed on Cu foil. Importantly, this strategy can avoid the poor contact problem between the current collector and electrode material as well as circumvent the addition of insulating material (binder) and inhomogeneous distribution of conductive carbon material and active material on the current collector. When evaluated as binder-free electrodes for LIBs, porous CuO NRAs deliver a high specific capacity (1341 mA h g–1 at 100 mA g–1) and enhanced rate capability and cycling ability (671 mA h g–1 at 100 mA g–1 after 150 cycles).

Preparation of Co3O4 hollow microsphere/graphene/carbon nanotube flexible film as a binder-free anode material for lithium-ion batteries

A flexible Co3O4 hollow microsphere/graphene/carbon nanotube hybrid film is successfully prepared through a facile filtration strategy and a subsequent thermally treated process. The composition, morphology, and structure of the as-prepared film are characterized by X-ray diffraction, X-ray photoelectron spectrometer, scanning electron microscopy, and transmission electron microscopy. Based on the morphology characterizations on the hybrid film, the Co3O4 hollow microspheres are uniformly and closely attached on three-dimensional (3D) graphene/carbon nanotubes (GR/CNTs) network, which decreases the agglomeration of Co3O4 microspheres effectively. In this hybrid film, the 3D GR/CNT network which enhances conductance as well as prevents aggregation is a benefit to help Co3O4 to exert its lithium storage capabilities sufficiently. When used as a binder-free anode material for lithium-ion batteries, the hybrid film delivers excellent electrochemical properties involving reversible capacity (863 mAh g−1 at a current density of 100 mA g−1) and rate performance (185 mAh g−1 at a current density of 1600 mA g−1).

Three-dimensional tin dioxide–graphene composite nanofiber membrane as binder-free anode for high-performance lithium-ion batteries

Commercialization of tin dioxide-based anodes for lithium-ion batteries has still not been achieved mainly due to the poor cycling performance caused by the huge volume changes of the electrodes. We herein synthesized a three-dimensional tin dioxide–graphene composite nanofiber (3D SnO2/GNF) membrane via a hydrothermal and electrospinning method assisted by a subsequent calcination process. In this cross-linked three-dimensional network, SnO2 particles are loaded on the graphene crystal structure uniformly, with the aggregation and volume expansion partially inhibited. As a free-standing 3D network, the resultant nanofiber membrane could be used as the anode directly without the addition of the binder and conductive agent. Serving as a binder-free anode material for LIBs, the SnO2/GNF anode exhibits good electrochemical performance with high reversible capacity and excellent cycling stability. More specifically, a high capacity of 763.9 mAh g−1 was obtained at a current density of 100 mA g−1 after 300 cycles. The extraordinary performance could be ascribed to the positive synergistic effect of the nanosized SnO2 particles and graphene.

Flexible carbonized cotton covered by graphene/Co-doped SnO2 as free-standing and binder-free anode material for lithium-ions batteries

A flexible carbonized cotton covered by graphene/Co-doped SnO2 (CGN/SnO2-Co) composite is prepared by in situ and subsequent microwave method, then followed by thermal annealing treatment. The SnO2 nanoparticles with ultra-small size are uniform decorated on the CGN framework, and Co element has been successful doping into SnO2. It is found that doping process does not affect the phase structure of SnO2, but great influence the morphology, the electrical conductivity, and the electrochemical properties on the composites. As a free-standing and binder-free anode for lithium-ions batteries, the discharge capacity of CGN/SnO2-Co have a high value of 549.6mAhg−1 (1996μAcm−2) after 100 cycles at a current density of 100mAg−1, which is much higher than those of cotton covered by graphene/SnO2 (CGN/SnO2) and cotton covered by graphene/Co3O4 (CGN/Co3O4) at the same current. The improved performance of CGN/SnO2-Co can be attributed to the highly stable and conductive CGN framework, ultra-small size of SnO2 nanoparticles, and Co doping effect. It is reasonable to believe that this work has a great potential improve the performance of energy storage devices.

One-pot Solvothermal Synthesis of CuS-CNTs Hybrid as Binder-free Anode Material for Lithium Ion Batteries

CuS-carbon nanotubes hybrid (CuS-CNTs) was prepared by a one-pot, microwave-assisted solvothermal method. The composition and structure of the hybrid were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. As a binder-free anode material for lithium-ion batteries, the hybrid exhibited high reversible capacity, good cycle stability and rate capability. The enhanced electrochemical performances can be attributed to binder-free electrode and synergetic effect between CuS and carbon nanotubes in the hybrid.

Nitrogen-doped carbon shell on metal oxides core arrays as enhanced anode for lithium ion batteries

Tailored synthesis of advanced core/shell composite electrodes is the key for construction of high-performance power sources. In this work, we report a facile combined strategy for fabrication of 3D porous NiO/nitrogen-doped carbon (NiO/N-C) core/shell nanosheets arrays by chemical bath deposition plus electro-deposition methods. Thin N-C shell is uniformly coated on the preformed NiO nanosheets forming composite arrays. As a binder-free anode material for lithium ion batteries, the resultant NiO/N-C core/shell naoosheets arrays electrode exhibits enhanced electrochemical performances with better cycle capability and improved rate performance. The N-doped composite core/shell architecture plays positive roles in the enhancement of electrochemical performance due to lower charge-transfer resistance, and better strain accommodation during the discharge/charge cycling. Our research may offer an attractive way for the construction of high-performance metal oxides electrodes for energy storage.

In-situ assembly of three-dimensional MoS2 nanoleaves/carbon nanofiber composites derived from bacterial cellulose as flexible and binder-free anodes for enhanced lithium-ion batteries

With the development of flexible and wearable energy devices, it is highly desirable to exploit flexible and cost-effective electrode materials. In this work, we report a facile and in-situ method for preparing a three-dimensional (3D), flexible and binder-free anode material, composing of leaf-like MoS2 nanostructures uniformly anchored on carbon nanofibers derived from carbonized bacterial cellulose (denoted as MoS2-cBC). With merits of high conductivity, good flexibility and high structural stability, the MoS2-cBC composite was directly used as the anode material and current collector for lithium ion batteries without any binder nor conductive additive. Moreover, owing to the synergistic effect of the uniformly deposited MoS2 nanoleaves and the 3D highly conductive carbon nanofibers, the MoS2-cBC anode exhibits impressively superior electrochemical performance. A high reversible charge capacity of 935mAhg−1 is achieved at 0.1Ag−1, while a capacity of 581mAhg−1 is maintained after 1000 cycles at 1Ag−1 with negligible decay, demonstrating much enhanced long-term cycling stability of the composite. The superior electrochemical performance together with the stability and cost-effective merits make the MoS2-cBC composite promising for next-generation energy storage devices.

Single Wall Carbon Nanotube-Containing PVA Based Carbon Nanofibers for Lithium Ion Battery Anodes

Lithium ion batteries have increasing importance due to the urgent demand for widespread applications in electric/hybrid vehicles, electronic devices, and the grid energy storage. Graphite is one of the most commonly used anode material with low theoretical capacity(372mAh/g) and limited rate capability. In order to improve battery Li-ion storage capacity many researchers have investigated different carbonaceous anode materials with various configurations. Among them, carbon nanofiber is of particular interest for providing high capacity and cycling stability due to its high surface area, porous structure and high electric conductivity which not only shorten the lithium ion path through the electrode but also provide large electrode/electrolyte interface for the charge-transfer reaction properties. Carbon nanofibers can be directly used as free standing and binder free anodes. There are several nanofiber production methods, among which electrospinning is the most promising due to its simplicity and versatility. Carbon nanofibers can be produced with different precursors such as Pitch, polyacrylonitrile(PAN), polyvinypyrrolidone(PVP), polyvinyl alcohol(PVA) etc. Polyvinyl alcohol is a promising material due to its water soluble and environmentally friendly character. In this study we report a method to produce free-standing binder free single wall carbon nanotube containing carbon nanofibers as anode for lithium ion battery. Composite nanofibers prepared via electrospinning of single wall carbon nanotubes (SWCNT) dispersed into polyvinyl alcohol solution, followed by iodination at 100°C and heat treatment in an inert atmosphere at 800°C. Carbon nanotubes were added to the polymer solution in different concentrations 0,1% , 1%, and 5 %. An increase of the carbon nanotube concentration in the fibers led to carbonized nanofiber mats with increased electrical conductivity. TGA and Raman analyses showed that carbon nanotubes presence improves the carbon yield of the mats and their handleability. Galvanostatic cycling tests of half cells revealed that addition of carbon nanotubes improves battery capacity. We attribute the capacity increase of the composite nanofibers to the carbon nanotubes structure. Moreover carbon nanotubes increased the handleabilitiy of the mat which is crucial for freestanding, binder free anode materials.

A Novel Nano-Structured Sn-SnO2-TiO2/Cu5Sn5 Composite Film Electrodeposited on Cu As High Capacity Anode Materials for Lithium Ion Batteries

Introduction. Lithium-ion batteries (LIB) have been widely used as power sources in many electric/electronic products such as cellular phones, digital cameras, portable computers, etc. Recently, considering on the applications in automobile industry for electric vehicles (EVs) and plug-in hybrid vehicles (PHVs), it is highly desirable to explore new electrode materials with higher power density and satisfied lifetime cycles to meet expanding needs for lithium-ion battery industry. Among various anode materials, Sn-based materials have attracted great attention as promising candidate materials for the replacement of the conventional carbonaceous anode materials of Li-ion batteries, owing to that the Sn materials, with good electrical conductivity, possess higher theoretical capacitance (Li4.4Sn: 994 mAh g-1) than graphite (LiC6: 372 mAh g-1). However, it is known that pure Sn material delivers substantial volume changes during alloying/de-alloying process with Li. During the charge-discharge cycles, volume change of Sn will cause the deterioration and peeling of the film electrode from the Cu electric collectors, thus resulting in rapid capacity fade and significantly affecting the cyclic lifetime of the batteries. In this study, we propose a novel nanoporous, bi-layered Sn-SnO2-TiO2/Cu6Sn5 (SSTC) composite film that directly electrodeposited on Cu sheets as binder-free and conductor-free anode material for Li-ion rechargeable batteries. Here, the nanoporous structure can provide space for the volume change of Sn material, and the TiO2 and Cu6Sn5 alloy can meditate the volume change inside the Sn-based composite film and at the film/Cu interface during the lithium insertion/extraction. Experimental. Various Sn-SnO2-based composite films were fabricated on Cu sheets by a hybrid electroplating method, i.e., combining electro-deposition with electrophoric deposition, using a mixed EtOH-H2O bath mainly containing SnCl2 and TiCl3, followed by annealing at 473 K for 2 h. The effects of ratios of [Sn2+]/[Ti3+] and EtOH/H2O, and operating conditions on the formation and microstructures of the plating films were investigated. The morphology, chemical composition, chemical state, and crystalline structure of the electrodeposited films before and after heat treatment were investigated by FE-SEM, EDX, TEM (FIB), XRD, and XPS. Moreover, electrochemical charge-discharge performances of the SSTC composite films on Cu were investigated with home-made pouch cells which assembled in an Ar-filled glove box. The cathode was utilized with a lithium metal foil, and the electrolyte solution was made of 1M LiPF6 in a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) with a volumetric ratio of 1:1:1, respectively. The cells were charged and discharged at 0.1 A g-1 by a battery test system, and the cut-off voltage range was 0.01 – 2.0 V or 0.01 – 3.0 V (vs. Li+/Li) at 50 – 100 mA g-1 and 303 K. Results and Discussion. Figs. 1a-b show the surface FESEM images of as-deposited Sn-TiO2 composite films on Cu sheets, which were fabricated in plating baths with different [Sn2+]/[Ti3+] ratios. It can be seen that the films composed of nano-flakes or nano-needles, thus making a networked nanoporous structure. The morphologies of the electrodeposited films were depended predominantly on ratios of [Sn2+]/[Ti3+] and EtOH/H2O in electroplating baths, while only slightly affected by operating conditions. According to EDX and XPS analysis, the electrodeposited films consisted of Sn, SnO2, and a small amount of TiO2 in 1–10 at%, in proportional to the [Sn2+]/[Ti3+] ratio. A representative cross-sectional TEM image in Fig.1c disclosed that the electrodeposited specimen after annealing at 473 K for 2h consisted in a nanoporous top-layer with scaly Sn nano-crystals and a dense under-layer of Cu-Sn alloy on Cu substrate. The corresponding XRD pattern of a SSTC composite film on Cu after annealed was illustrated in Fig.1d. The Sn electrodeposits had a polycrystalline structure with a preferential in Sn (200) facet. In addition, an intermetallic compound of Sn and Cu in form of h-Cu6Sn5 was also detected, which can be attributed to the alloying reaction at the interface between the Sn-TiO2 deposited film and Cu substrate during annealing. Moreover, galvanostatic charge/discharge tests revealed that the SSTC composite films delivered a high initial specific discharge capacities of 1042 mAh g-1, with a maximum value of 1227 mAh g-1, and a high Coulombic efficiency of more than 90%, indicating a promising future as binder-free and conductor-free anode materials for LIBs. Figure 1

MOFs nanosheets derived porous metal oxide-coated three-dimensional substrates for lithium-ion battery applications

Porous nanosheet-structured materials have received great attention because of their promising applications in energy field. Construction of porous metal oxides nanosheets on three-dimensional (3D) electro-conductive substrates is an effective way to further enhance electrochemical performance of energy storage devices. Herein, porous transition metal oxides (i.e. ZnO, Co3O4) nanosheets derived from MOFs coated 3D substrates (i.e. 3D nickel foam, carbon fiber) are successfully synthesized by a facile liquid-phase deposition method with subsequent calcination. The growth mechanism of MOFs with nanosheet morphology coated 3D substrates is investigated. As a proof of concept application, the Co3O4/3DNF hybrid, possessing the advantages of porous nanosheet-structured and 3D electro-conductive substrates, is used as a binder-free anode material for lithium-ion battery, which exhibits high-rate capability and long-term cyclic stability. High discharge capacities of 1135, 1268, 1226, 1130, 923, 751, and 543mAhg−1 are obtained at the current densities of 0.2, 0.5, 1, 2, 5, 10, and 20Ag−1, respectively. Even measured at 25Ag−1, it still retains a desired discharge capacity of 364mAhg−1. Besides, the long-term cyclic stability up to 2000 cycles can be obtained at 5Ag−1 and 20Ag−1.

Porous CoFe2O4 nanowire arrays on carbon cloth as binder-free anodes for flexible lithium-ion batteries

A three-dimensional CoFe2O4 nanowire array on carbon cloth was fabricated with a hydrothermal method together with a post-annealing treatment. As a binder-free and flexible anode material for LIBs, it showed an improved electrochemical performance with high cycling stability and excellent rate capability. It exhibited an initial discharge capacity of 1615mAhg−1 and retained a reversible capacity of about 1204mAhg−1 after 200 cycles at a specific current of 500mAg−1. The high capacity, outstanding rate performance and cycling stability can be attributed to the special configuration of hierarchal porous CoFe2O4 nanowires on carbon cloth, which possess many advantages like short diffusion length, easy strain relaxation and fast electron transport. Moreover, the integrated CoFe2O4 nanowires/carbon cloth electrode shows high flexibility and high areal capacity (2.41mAhcm−2), which makes it suitable for use as a binder-free anode to build flexible LIBs.

Porous Mn3O4 nanorod/reduced graphene oxide hybrid paper as a flexible and binder-free anode material for lithium ion battery

A highly flexible and free-standing, porous Mn3O4 nanorod/reduced graphene oxide (pMn3O4 NR/rGO) paper was prepared by a two-step process: vacuum filtration and thermal treatment. The MnOOH nanorod/graphene oxide (MnOOH NR/GO) paper obtained by a simple filtration method is transformed into pMn3O4 NR/rGO paper after a thermal reduction process. A unique lamellar structure was achieved with pMn3O4 NR homogeneously intercalated within the GO layers. In the hybrid structure, graphene nanosheets provide a conductive pathway and act as the buffer layers to prevent the pulverization of pMn3O4 NRs during reaction. Therefore, when used as the anode in lithium ion batteries, this pMn3O4 NR/rGO paper exhibits a first high discharge capacity of 943 mA h g−1, which quickly stabilizes and remains at 573 mA h g−1 even after 100 cycles at 100 mA h g−1, which is much higher than the discharge capacity of the corresponding pristine graphene paper (183 mA h g−1).

Controlled Synthesis of Carbon Nanofibers Anchored with Zn(x)Co(3-x)O4 Nanocubes as Binder-Free Anode Materials for Lithium-Ion Batteries.

The direct growth of complex ternary metal oxides on three-dimensional conductive substrates is highly desirable for improving the electrochemical performance of lithium-ion batteries (LIBs). We herein report a facile and scalable strategy for the preparation of carbon nanofibers (CNFs) anchored with ZnxCo3-xO4 (ZCO) nanocubes, involving a hydrothermal process and thermal treatment. Moreover, the size of the ZCO nanocubes was adjusted by the quantity of urea used in the hydrothermal process. Serving as a binder-free anode material for LIBs, the ZnCo2O4/CNFs composite prepared using 1.0 mmol of urea (ZCO/CNFs-10) exhibited excellent electrochemical performance with high reversible capacity, excellent cycling stability, and good rate capability. More specifically, a high reversible capacity of ∼600 mAh g(-1) was obtained at a current density of 0.5 C following 300 charge-discharge cycles. The excellent electrochemical performance could be associated with the controllable size of the ZCO nanocubes and synergistic effects between ZCO and the CNFs.

A novel strategy to prepare Sb thin film sandwiched between the reduced graphene oxide and Ni foam as binder-free anode material for lithium-ion batteries

A simple and inexpensive route is developed to synthesis the Sb thin film sandwiched between the reduced graphene oxide and the Ni foam (RGO-SbTF-Ni) by a galvanic replacement reaction along with a pulse electrophoretic deposition route. As a binder-free anode material for lithium ion batteries, the RGO-SbTF-Ni exhibits a high initial discharge capacity of 872.9mAhg−1 and an enhanced coulombic efficiency of 66.0% at a current density of 100mAg−1 in the first cycle. In addition, a substantial discharge capacity of 424.1mAhg−1 can be retained even after 50 repeated cycles. The enhanced performances of the designed binder-free anode material can be attributed to the novel hierarchical sandwich laminated structure with an excellent electrical contact, and the synergistic effect between the Sb thin film with high specific capacity and flexible RGO with good buffer effect to alleviate the strain caused by the large volume change.

Controllable synthesis of carbon-coated Sn⿿SnO2⿿carbon-nanofiber membrane as advanced binder-free anode for lithium-ion batteries

A carbon-coated composite consisting of Sn, SnO2, and porous carbon-nanofiber membrane (Sn⿿SnO2⿿CNF@C) was successfully prepared via electrospinning followed by carbonization and low-temperature hydrothermal treatment. The thickness of the carbon overlayer formed by using sucrose as the carbon source could be well controlled by adjusting the sucrose concentration. The three-dimensional (3D) nanofiber network structure allowed the Sn⿿SnO2⿿CNF@C membrane to be used directly as an anode in lithium-ion batteries without adding any polymer binders or electrical conductors. The composite electrodes of this material exhibited a high discharge capacity of 712.2mAhg⿿1 at a high current density of 0.8Ag⿿1 after 200 cycles, as well as good cycling stability and excellent rate capability, which can be ascribed to the improved electrochemical properties of the Sn⿿SnO2 particles provided by the protective carbon coating and the 3D carbon nanofiber membrane. The composite can thus be widely used as an advanced binder-free anode material in high-current rechargeable lithium-ion batteries and extended to the fabrication of flexible electrodes.

Fe2O3–SnO2–graphene films as flexible and binder-free anode materials for lithium-ion batteries

Abstract

Facile synthesis of MgCo2O4 nanowires as binder-free flexible anode materials for high-performance Li-ion batteries

MgCo2O4 nanowires are synthesized for the first time through two-step synthesis method, followed by annealing of the MgCo2O4 precursors. The microstructure and morphology of MgCo2O4 nanowires are examined by powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. MgCo2O4 nanowires give rise to a BET surface area of 45.1 m2 g−1 and the adsorption average pore size of 11.5 nm. When tested as an anode for lithium-ion batteries, the MgCo2O4 nanowires electrode exhibit exceptional properties in terms of specific capacity, cycling performance, and rate capacity compared with previously reported Co-based binary metal oxides. For instance, when the current densities increase from 5, 10, 15, and 20 A g−1, the discharge capacities of the MgCo2O4 nanowires electrode are about 649, 348, 188, and 121 mAh g−1, respectively. The enhanced electrochemical performance of the MgCo2O4 nanowires can be mainly attributed to the nanostructures which lead to decreased lithium-ion diffusion distances and increased active sites for Li insertion/extraction reactions.