Binder-free Anode For Lithium-ion Batteries Research Articles

Forcespinning: An Alternative Method to Produce Metal-Oxides/Carbon Composite Fibers as Anode Materials for Lithium-Ion Batteries

We present results on the Forcespinning (FS) of Metal-oxides (MOx)/PAN fiber precursors for the mass production of MOx/C composite fibers as anode materials for Lithium-ionbatteries. Metal oxides such as NiO, CuO, ZnO and SnO2, were chosen with carbon fiber matrix as the active materials for the composite fiber anodes. The microfiber preparation process involved the FS of MOx/PAN precursors into microfibers and subsequent stabilization in air at 280ºC and calcination at 700ºC under Argon atmosphere. The MOx/C composite fiber anodes exhibited a specific discharge capacity between 300 and 800 mAhg-1 at the first cycle and a high irreversible capacity. The initial high irreversible capacity observed for most MOx/C composite fibers, was attributed to the formation of the SEI layer and the high surface area of the Forcespun composite microfibers. In the subsequent cycles, the MOx/C composite fiber anodes exhibited a much stable cycling performance, .i.e. 200-300 mAhg-1 was maintained after 100 cycles at 100 mAg-1. The observed electrochemical performance and the simple processing method of these MOx/C composite fibers makes them promising candidates for next generation and cost effective flexible binder-free anodes for Lithium-ion batteries.

Sn-Cu nanotubes enveloped in three-dimensional interconnected polyaniline hydrogel framework as binder-free anode for lithium-ion battery

The novel Sn-Cu nanotubes enveloped in three-dimensional (3D) hierarchical polyaniline (PANI) hydrogel (Sn-Cu/PANI) were successfully prepared as a high performance anode for lithium-ion battery. The binder-free electrode exhibits reversible capacity of 548mA h g−1 after 500 cycles and admirable rate capacity even up to 5000mAg−1. The exceptional electrochemical performance of Sn-Cu/PANI hydrogel could be attributed to the unique structure: (1) The inactive Cu matrix in binary Sn-Cu compounds and the tubular construction conduce to relieve the volume swing; The high porosity originated from galvanic replacement reaction accelerates ions transmission, which contributes to rapid charging and discharging. (2) The 3D porous PANI framework offers a continuous electron and lithium ions transport network among the whole electrode; the hierarchical PANI serves as mechanical support to accommodate the stress related to the large volume change of Sn-Cu nanotubes, thus reducing the risk of electrode pulverization.

Three-dimensional Zn3V3O8/carbon fiber cloth composites as binder-free anode for lithium-ion batteries

Ternary metal vanadium oxides have been considered as potential anode materials for lithium-ion batteries (LIBs). However, the poor electronic conductivity and large volume expansion during the discharge/charge process lead to poor electrochemical performance. Herein, we firstly report the preparation of grass-like Zn3V3O8 nanobelts array coated 3D carbon fiber cloth (Zn3V3O8/CFC) as a binder-free anode for LIBs. The composites could effectively improve the kinetics of electronic transportation and mitigate the volume expansion of electrodes during discharge/charge process. As a result, the Zn3V3O8/CFC exhibits excellent Li+ storage properties. It can deliver a reversible capacity of ∼1750mAhg−1 at a low current density of 100mAg−1 and a specific capacity of 942mAhg−1 at the high rate of 1.5Ag−1. Even measured at high current density of 5Ag−1, the electrode could maintain a high capacity of 455mAhg−1 after 500 cycles with a capacity retention of 82.7%.

Three-dimensional ordered macroporous Cu/Fe3O4 composite as binder-free anode for lithium-ion batteries

A novel three-dimensional ordered macroporous (3DOM) Cu/Fe3O4 composite film was prepared by electrodepositing ferroferric oxide (Fe3O4) on the 3DOM Cu current collector. Characterizations via electron microscopies and X-ray diffractions confirmed that achieved 3DOM Cu/Fe3O4 composite inherited originally ordered porous structure, but has a layer of nanosized Fe3O4 on the surface of the 3DOM Cu framework. The obtained 3DOM Cu/Fe3O4 composite films were directly used as anodes of lithium ion batteries in the absence of conducting additives or binders. Results from electrochemical evaluations exhibited that the 3DOM Cu/Fe3O4 anode could deliver a stable capacity of 800 mAh g−1 up to 400 cycles, while fast capacity degradation with 200 mAh g−1 retained after 100 cycles was observed on Fe3O4 deposited on plane Cu substrate. The superior behavior of the 3DOM Cu/Fe3O4 composite anode is ascribed to its unique porous structure, which provides sufficient space for large volume change of Fe3O4 and greatly reduces the diffusion distance for Li-ion in the active material.

Self-standing silicon-carbon nanotube/graphene by a scalable in situ approach from low-cost Al-Si alloy powder for lithium ion batteries

Silicon/carbon (Si/C) composite shows great potential to replace graphite as lithium-ion battery (LIB) anode owing to its high theoretical capacity. Exploring low-cost scalable approach for synthesizing Si/C composites with excellent electrochemical performance is critical for practical application of Si/C anodes. In this study, we rationally applied a scalable in situ approach to produce Si-carbon nanotube (Si-CNT) composite via acid etching of commercial inexpensive micro-sized Al-Si alloy powder and CNT mixture. In the Si-CNT composite, ∼10 nm Si particles were uniformly deposited on the CNT surface. After combining with graphene sheets, a flexible self-standing Si-CNT/graphene paper was fabricated with three-dimensional (3D) sandwich-like structure. The in situ presence of CNT during acid-etching process shows remarkable two advantages: providing deposition sites for Si atoms to restrain agglomeration of Si nanoparticles after Al removal from Al-Si alloy powder, increasing the cross-layer conductivity of the paper anode to provide excellent conductive contact sites for each Si nanoparticles. When used as binder-free anode for LIBs without any further treatment, in situ addition of CNT especially plays important role to improve the initial electrochemical activity of Si nanoparticles synthesized from low-cost Al-Si alloy powder, thus resulting in about twice higher capacity than Si/G paper anode. The self-standing Si-CNT/graphene paper anode exhibited a high specific capacity of 1100 mAh g−1 even after 100 cycles at 200 mA g−1 current density with a Coulombic efficiency of >99%. It also showed remarkable rate capability improvement compared to Si/G paper without CNT. The present work demonstrates a low-cost scalable in situ approach from commercial micro-sized Al-Si alloy powder for Si-based composites with specific nanostructure. The Si-CNT/graphene paper is a promising anode candidate with high capacity and cycling stability for LIBs, especially for the flexible batteries application.

Hierarchical shell/core CuO nanowire/carbon fiber composites as binder-free anodes for lithium-ion batteries

Developing high-performance electrode structures is of great importance for advanced lithium-ion batteries. This study reports an efficient method to fabricate hierarchical shell/core CuO nanowire/carbon fiber composites via electroless plating and thermal oxidation processes. With this method, a binder-free CuO nanowire/carbon fiber shell/core hierarchical network composite anode for lithium-ion batteries is successfully fabricated. The morphology and chemical composition of the anode are characterized, and the electrochemical performance of the anode is investigated by standard electrochemical tests. Owing to the superior properties of carbon fibers and the morphological advantages of CuO nanowires, this composite anode still retains an excellent reversible capacity of 598.2mAhg−1 with a capacity retention rate above 86%, even after 50 cycles, which is much higher than the CuO anode without carbon fibers. Compared to the typical CuO/C electrode systems, the novel binder-free anode yields a performance close to that of the typical core/shell electrode systems and a much higher reversible capacity and capacity retention than the similar shell/core patterns as well as the anodes with binders. It is believed that this novel anode will pave the way to the development of binder-free anodes in response to the increasing demands for high-power energy storage.

Hierarchical carbon cloth supported Li4Ti5O12@NiCo2O4 branched nanowire arrays as novel anode for flexible lithium-ion batteries

Abstract The hierarchical carbon cloth supported Li 4 Ti 5 O 12 @NiCo 2 O 4 branched nanowire (NW) arrays were fabricated as the flexible, binder-free anode for lithium-ion batteries. The novel composite exhibits greatly improved specific capacity and rate capability as well as excellent cyclic stability compared to carbon cloth supported Li 4 Ti 5 O 12 NW arrays. The results clearly demonstrate that branched growth of NiCo 2 O 4 NWs on the surface of Li 4 Ti 5 O 12 NWs on carbon cloth enhances lithium diffusion. The superior electrochemical performance is ascribed to the unique architecture as well as the synergetic effect of good flexibility and high conductivity of carbon cloth, almost zero volume change during charge/discharge process of Li 4 Ti 5 O 12 , and high capacity and conductivity of NiCo 2 O 4 . This novel anode possesses high potential for applications in high-performance, flexible lithium-ion batteries.

Graphene‐Encapsulated Copper tin Sulfide Submicron Spheres as High‐Capacity Binder‐Free Anode for Lithium‐Ion Batteries

AbstractSn‐based sulfides are potential anode materials for lithium‐ion batteries (LIBs); nevertheless, they typically suffer from poor cycle stability resulted from the huge volume variation during lithium‐ion insertion and extraction. Herein, we successfully fabricated the multiphase Cu2Sn3S7/Cu2SnS3/SnS2 (CTS) submicron spheres uniformly incorporated with reduced graphene oxide nanosheets (CTS@RGO). This binder‐free hybrid CTS@RGO paper exhibits favorable capacity retention as an anode of LIBs (965 mAh g−1 after 300 cycles at current density of 500 mA g−1), as well as better rate capability and high initial coulombic efficiency compared with that of a pristine CTS anode. The enhanced electrochemical performance can be ascribed to the introduction of graphene as a buffer to accommodate large volume changes and to maintain structural integrity of electrode.

Three-dimensional carbon cloth-supported ZnO nanorod arrays as a binder-free anode for lithium-ion batteries

Three-dimensional ZnO nanorod arrays on flexible high surface area carbon cloth were successfully synthesized and directly used as negative electrodes for lithium-ion batteries without using any binder additive. The structure and morphology of the as-prepared hybrid ZnO electrode were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). When tested as anodes in a lithium cell, the hybrid electrode demonstrated a high discharge capacity along with excellent rate capability and good cycling stability, delivering a reversible capacity of 891 mAh g−1 at the second cycle and retaining a capacity of 469 mAh g−1 after 100 cycles.

Electrospun Carbon Fiber/Ni–Co Composites as Binder-Free Anodes for Lithium-Ion Batteries

Binder-free anodes composed of electrospun carbon fibers were prepared for lithium-ion batteries. Nickel−cobalt binary hydroxide (Ni−Co(OH)2) was coprecipitated on the electrospun carbon fibers to form a hierarchical structure with Ni−Co(OH)2 nanoflakes vertically attached on the fiber surface. When the composite fibers were annealed in air, Ni−Co(OH)2 nanoflakes were converted to NiCo2O4 nanosheets at 300°C. Further increasing the annealing temperature to 400°C resulted in the aggregation of NiCo2O4 on the fiber surface, causing the loss of NiCo2O4 nanostructures. When used as anodes, the composite fibers exhibited the higher specific capacity than the pristine carbon fibers. This was attributed to the hierarchical structure of the composite fibers in which the high surface area and rich mesopores of Ni−Co compounds provided easily accessible ion transport across electrolyte/electrode interfaces and additional lithium storage, respectively. Additionally, Ni−Co compounds possessed the high theoretical capacities. By contrast, the interconnected carbon fibers served as a conductive path for charge transfer. They also acted as a buffer to alleviate the Ni−Co-compound volume expansion and contraction during discharging and charging. Among all the samples, the composite fibers annealed at 300°C exhibited the highest capacity of 734 mAh g−1 at a current density of 150 mA g−1.

Hollow core–shell structured silicon@carbon nanoparticles embed in carbon nanofibers as binder-free anodes for lithium-ion batteries

Abstract Silicon is regarded as one of the most promising candidates for lithium-ion battery anodes owing to its large theoretical energy density (about 4200 mAh g−1) and low working potential (vs. Li/Li+). However, its practical application is limited by structure degradation and a comparatively poor capacity retention caused by large volume changes during cycling. In this study, we have prepared a novel nanofiber form of silicon/carbon with hollow core–shell structured silicon@carbon (Si@C) nanoparticles embedded in carbon nanofibers. Voids between the silicon nanoparticle (SiNP) core and carbon shell help to accommodate the volume expansion associated with the lithiation/delithiation process in a working electrode and allow formation of a stable solid electrolyte interphase (SEI) film. The obtained electrodes exhibited good cycle performance with a high reversible capacity of 1020.7 mAh g−1 after 100 cycles at a current density of 0.2 A g-1, and also delivered excellent cycling performance at a high current density of 3.2 A g-1. The design of this new structure provides a potential method for developing other functional composite anode materials with high reversible capacities and long-term cycle stabilities.

Self-assembled cauliflower-like FeS2 anchored into graphene foam as free-standing anode for high-performance lithium-ion batteries

For the first time, self-assembled cauliflower-like FeS2 anchored into three-dimensional graphene foams (3DGF-FeS2) are synthesized by one-pot hydrothermal method. Without polymeric binders, conductive additives, or metallic current collectors, the 3DGF-FeS2 composite can be directly used as freestanding and binder-free anode for lithium-ion batteries (LIBs), which demonstrates pronounced electrochemical performance: it exhibits a large initial capacity of 1251.3 mAh g−1 and remains 1080.3 mAh g−1 after 100 cycles at 0.2 C, which is much higher than the theoretical capacity (890 mAh g−1) of bare FeS2 bulk material; it delivers excellent high-rate performance with a capacity of 615.1 mAh g−1 even at 5 A g−1. The pronounced enhancement in electrochemical performance is mainly attributed to the synergistic effect of 3DGF matrix and the unique self-assembly architecture. The porous and conductive 3DGF network offers efficient channels for electron transfer and ionic diffusion and the self-assembled cauliflower-like architecture restrains the aggregation of FeS2 and enhance the stability of 3DGF-FeS2 by suppressing the volume expansion during cycling processes. The 3DGF-FeS2 is promising as superior-capacity free-standing and binder-free anode for LIBs.

Facile fabrication of MOF-derived octahedral CuO wrapped 3D graphene network as binder-free anode for high performance lithium-ion batteries

In this work, an effective and facile strategy to fabricate binder-free electrodes composing 3D graphene network (3DGN) and octahedral CuO has been proposed. In this design, Cu-based MOF crystals were first uniformly grown on the surface of 3DGN substrate through a solution immersion method and then a subsequent thermal treatment isolated the formation of well-dispersed nanostructured CuO octahedras wrapped 3DGN. The obtained 3DGN/CuO composites were utilized as binder-free anodes of lithium-ion batteries for the first time, yielding a high reversible gravimetric capacity of 409mAhg−1 (a large areal capacity of 0.39mAhcm−2) at 100mAg−1, excellent cyclability with 99% capacity retention after 50 cycles and superior rate capability of 219mAhg−1 at 1600mAg−1. The remarkable performance of the composite electrode can be reasonably attributed to the synergistic interaction between octahedral CuO nanoparticles with high capacity and the conductive 3D graphene network with a large surface area and an interconnected porous structure.

Corrigendum to ‘Graphite-coated ZnO nanosheets as high-capacity, highly stable, and binder-free anodes for lithium-ion batteries’ [J. Power Sources 320 (2016) 314–321

Corrigendum to ‘Graphite-coated ZnO nanosheets as high-capacity, highly stable, and binder-free anodes for lithium-ion batteries’ [J. Power Sources 320 (2016) 314–321

Free-standing Ca2Ge7O16 nanorod arrays anode with long-term stability and superior rate capability in lithium ion batteries

We report a facile one-step route to synthesize a free-standing Ca2Ge7O16 nanorod anode for the first time. The Ca2Ge7O16 nanorod arrays are uniformly grown on the surface of three-dimensional copper foam used as the conductive current collector. The Ca2Ge7O16 nanorod is used as a binder-free anode for lithium-ion batteries, which exhibits excellent cycle performance (134.6% retention of its 1st cycle reversible capacity after 450cycles) and superior rate capability (350mAhg−1 at 5Ag−1, the good cycling stability at 20Ag−1). Even at higher current density of 0.5Ag−1 after 10cycles activation at 0.2Ag−1, the nanorod electrodes can deliver a reversibility capacity as high as 1001.2mAhg−1. Furthermore, a binder free full cell is fabricated, which shows excellent cycle performance with 91% retention of its 1st cycle capacity after 200cycles. The superior cycling performance is attributed to shortened Li+ transport length, enough buffering space, electrical conductivity of the Cu foam and the unique 1 D nanorod arrays structure.

Silicon-Reduced Graphene Oxide Self-Standing Composites Suitable as Binder-Free Anodes for Lithium-Ion Batteries.

Silicon-reduced graphene oxide (Si-rGO) composites processed as self-standing aerogels (0.2 g cm-3) and films (1.5 g cm-3) have been prepared by the thermal reduction of composites formed between silicon nanoparticles and a suspension of graphene oxide (GO) in ethanol. The characterization of the samples by different techniques (X-ray diffraction, Raman, thermogravimetric analysis, and scanning electron microscopy) show that in both cases the composites are formed by rGO sheets homogeneously decorated with 50 nm silicon nanoparticles with silicon contents of ∼40% wt. The performances of these self-standing materials were tested as binder-free anodes in lithium-ion batteries (LIBs) in a half cell configuration under two different galvanostatic charge-discharge cutoff voltages (75 and 50 mV). The results show that the formation of a solid electrolyte interphase (SEI) is favored in composites processed as aerogels due to its large exposed surface, which prevents the activation of silicon when they are cycled within the 2 to 0.075 V voltage windows. It is also found that the composites processed in the form of self-standing films exhibit good stability over the first 100 cycles, high reversible specific capacity per mass of electrode (∼750 mAh g-1), areal capacities that reach 0.7 mAh cm-2, and high Coulombic efficiencies (80% for the first charge-discharge cycle and over 99% in the subsequent cycles).

Improved lithium-ion battery anode capacity with a network of easily fabricated spindle-like carbon nanofibers.

A novel network of spindle-like carbon nanofibers was fabricated via a simplified synthesis involving electrospinning followed by preoxidation in air and postcarbonization in Ar. Not only was the as-obtained carbon network comprised of beads of spindle-like nanofibers but the cubic MnO phase and N elements were successfully anchored into the amorphous carbon matrix. When directly used as a binder-free anode for lithium-ion batteries, the network showed excellent electrochemical performance with high capacity, good rate capacity and reliable cycling stability. Under a current density of 0.2 A g−1, it delivered a high reversible capacity of 875.5 mAh g−1 after 200 cycles and 1005.5 mAh g−1 after 250 cycles with a significant coulombic efficiency of 99.5%.

Morphology-Tuned NiCo2O4-Coated 3D Graphene Rrchitectures As Binder-Free Electrode for Lithium Ion Battery

In recent decades, lithium ion batteries (LIBs) have been considered as the most effective and practical technology products for portable electronic devices because of their flexibility, high energy density and long lifespan. Nanostructured transition metal oxides have been intensively studied as one of the most promising candidates for LIBs because of their high theoretical capacities (500-1000 mAh g-1), good reversible conversion, and low cost. However, in general, poor cycling performance and low electrical conductivity have hindered their practical application. Recently, 3D graphene synthesized by chemical vapor deposition (CVD) method has been studied extensively and used as a binder-free electrode in energy storage devices because of its excellent electron conductivity as current collector and high stability in electrolyte, but the application of 3D graphene as free-standing electrode is still limited due to its weak mechanical strength. In this work, nanostructured NiCo2O4 is directly grown on the surface of three-dimensional graphene-coated nickel foam (3D-GNF) by a facile electrodeposition technique and subsequent annealing. The resulting NiCo2O4 possesses a distinct flower or sheet morphology tuned by potential or current variation electrodeposition, which is used as a binder-free lithium ion battery anode for the first time. Both samples exhibit high lithium storage capacity profiting from unique binder-free electrode structures. The flower-type NiCo2O4 demonstrates high reversible discharge capacity (1459 mAh g–1 at 200 mA g–1) and excellent cyclability with around 71% retention of the reversible capacity after 60 cycles, which are superior to sheet-type NiCo2O4. Such superb performance can be attributed to high volume utilization efficiency with unique morphological character, a well-preserved connection of active materials to the current collector, a short lithium ion diffusion path, and fast electrolyte transfer in binder-free NiCo2O4-coated 3D graphene structure. The simple preparation process and easily controllable morphology make binder-free NiCo2O4/3D-GNF hybrid a potential material for commercial application.

Three-dimensional core-shell Fe2O3 @ carbon/carbon cloth as binder-free anode for the high-performance lithium-ion batteries

A facile and scalable strategy is developed to fabricate three dimensional core-shell Fe2O3 @ carbon/carbon cloth structure by simple hydrothermal route as binder-free lithium-ion battery anode. In the unique structure, carbon coated Fe2O3 nanorods uniformly disperse on carbon cloth which forms the conductive carbon network. The hierarchical porous Fe2O3 nanorods in situ grown on the carbon cloth can effectively shorten the transfer paths of lithium ions and reduce the contact resistance. The carbon coating significantly inhibits pulverization of active materials during the repeated Li-ion insertion/extraction, as well as the direct exposure of Fe2O3 to the electrolyte. Benefiting from the structural integrity and flexibility, the nanocomposites used as binder-free anode for lithium-ion batteries, demonstrate high reversible capacity and excellent cyclability. Moreover, this kind of material represents an alternative promising candidate for flexible, cost-effective, and binder-free energy storage devices.

Multichannel hollow structure for improved electrochemical performance of TiO2/Carbon composite nanofibers as anodes for lithium ion batteries

With nanofibers receiving much attention in the application of lithium ion batteries (LIBs), we herein report the use of multichannel hollow nanofibers composed of TiO2 and Carbon as a binder-free anode for LIBs. The nanofibers were produced by the Forcespinning® of an emulsion precursor solution composed of Polyvinylpyrrolidone (PVP), Titanium (IV) butoxide, ethanol, acetic acid, and mineral oil. The as-prepared precursor nanofibers were subjected to a thermal treatment by first stabilizing in air at 280 °C followed by carbonizing at 550 °C under an argon atmosphere to form TiO2/C composite multichannel hollow nanofibers without the need for a sacrificial polymer to produce this morphology. This fibers’ hollow structure resulted in improved electrochemical performance when compared to non-hollow fibers. These hollow fibers also showed excellent cycling performance with a specific capacity of 228.9 mAhg−1 at a current density of 100 mAg−1 while maintaining a Coulombic efficiency of ∼98% after 100 cycles compared to the TiO2/C non-hollow fibers which showed a capacity of 61.4 mAhg−1. These composite hollow nanofibers show a great promise as alternative anode materials for next generation LIBs.