In-situ grown hierarchical ZnCo2O4 nanosheets on nickel foam as binder-free anode for lithium ion batteries

Nickle foam-supported hierarchical ZnCo₂O₄ nanosheets was prepared via a facile solution-based method. Porous ZnCo₂O₄ nanosheets were in-situ grown on current collector, forming a binder-free electrode. When evaluated as anode for Lithium ion batteries (LIB_S), the binder-free electrode showed an attractive electrochemical performance. A reversible capacity of 773?mAh?g^?1 could be stably delivered after a 500-cycle test at a current density of 0.25?A?g^?1, with a high capacity retention of 87%. The electrode could maintain a high reversible capacity of 245?mA?h?g^?1 even at an elevated current density of 8.0?A?g^?1. Integrated structure and rich porosity of the binder-free electrode were believed to contribute to the superior performance. Thus, the Nickle foam-supported ZnCo₂O₄ electrode is a promising anode for high performance LIBs in the coming future.     

A novel “plane-line-plane” nanostructure of the sandwich-like CNTs@SnO2/Ti3C2Tx 3D nanocomposite as a promising anode for lithium-ion batteries

As one of the novel two-dimensional metal carbides, Ti₃C₂T_x has received intense attention for lithium-ion batteries. However, Ti₃C₂T_x has low intrinsic capacity due to the fact that the surface functionalization of F and OH blocks Li ion transport. Herein a novel “plane-line-plane” three-dimensional (3D) nanostructure is designed and created by introducing the carbon nanotubes (CNTs) and SnO₂ nanoparticles to Ti₃C₂T_x via a simple hydrothermal method. Due to the capacitance contribution of SnO₂ as well as the buffer role of CNTs, the as-fabricated sandwich-like CNTs@SnO₂/Ti₃C₂T_x nanocomposite shows high lithium ion storage capabilities, excellent rate capability and superior cyclic stability. The galvanostatic electrochemical measurements indicate that the nanocomposite exhibits a superior capacity of 604.1 mAh g^?1 at 0.05?A?g^?1, which is higher than that of raw Ti₃C₂T_x (404.9 mAh g^?1). Even at 3?A?g^?1, it retains a stable capacity (91.7 mAh g^?1). This capacity is almost 5.6 times higher than that of Ti₃C₂T_x (16.6 mAh g^?1) and 58 times higher than that of SnO₂/Ti₃C₂T_x (1.6 mAh g^?1). Additionally, the capacity of CNTs@SnO₂/Ti₃C₂T_x for the 50th cycle is 180.1 mAh g^?1 at 0.5?A?g^?1, also higher than that of Ti₃C₂T_x (117.2 mAh g^?1) and SnO₂/Ti₃C₂T_x (65.8 mAh g^?1), respectively.     

Nanoparticles constructed mesoporous coral-like Mn2O3 as high performance anode for lithium-ion batteries

As well established, the morphology and architecture of electrode materials greatly contribute to the electrochemical properties. Herein, a novel structure of mesoporous coral-like manganese (III) oxide (Mn₂O₃) is synthesized via a facile solvothermal method coupled with the carbonization under air. When fabricated as anode electrode for lithium-ion batteries (LIBs), the as-prepared Mn₂O₃ exhibits good electrochemical properties, showing a high discharge capacity of 1090.4 mAh g^?1 at 0.1 A g^?1, and excellent rate performance of 410.4 mAh g^?1 at 2 A g^?1. Furthermore, it maintains the reversible discharge capacity of 1045 mAh g^?1 at 0.1 A g^?1 after 380 cycles, and 755 mAh g^?1 at 1 A g^?1 after 450 cycles. The durable cycling stability and outstanding rate performance can be attributed to its unique 3D mesoporous structure, which is favorable for increasing active area and shortening Li⁺ diffusion distance.     

Carbon-coated Bi5Nb3O15 as anode material in rechargeable batteries for enhanced lithium storage

Bismuth can alloy with lithium to generate Li₃Bi with the volumetric capacity of about 3765 mAh cm^?3 (386 mAh g^?1), rendering bismuth-based materials as attractive alloying-type electrode materials for rechargeable batteries. In this work, bismuth-based material Bi₅Nb₃O₁₅ @C is fabricated as anode material through a traditional solid-state reaction with glucose as carbon source. Bi₅Nb₃O₁₅ @C composite is well dispersed, with small particle size of 0.5–2.0?µm. The electrochemical performance of Bi₅Nb₃O₁₅ @C is reinforced by carbon-coated layer as desired. The Bi₅Nb₃O₁₅ @C exhibits a high specific capacity of 338.56 mAh g^?1 at a current density of 100?mA?g^?1. And it also presents an excellent cycling stability with a capacity of 212.06 mAh g^?1 over 100 cycles at 100?mA?g^?1. As a comparison, bulk Bi₅Nb₃O₁₅ without carbon-coating only remains 319.62 mAh g^?1 at 100?mA?g^?1, revealing poor cycle and rate performances. Furthermore, in-situ X-ray diffraction experiments investigate the alloying/dealloying behavior of Bi₅Nb₃O₁₅ @C. These insights will benefit the discovery of novel anode materials for lithium-ion batteries.     

High-performance binder-free supercapacitor electrode by direct growth of cobalt-manganese composite oxide nansostructures on nickel foam

A facile approach composed of hydrothermal process and annealing treatment is proposed to directly grow cobalt-manganese composite oxide ((Co,Mn)₃O₄) nanostructures on three-dimensional (3D) conductive nickel (Ni) foam for a supercapacitor electrode. The as-fabricated porous electrode exhibits excellent rate capability and high specific capacitance of 840.2 F g^-1 at the current density of 10 A g^-1, and the electrode also shows excellent cycling performance, which retains 102% of its initial discharge capacitance after 7,000 cycles. The fabricated binder-free hierarchical composite electrode with superior electrochemical performance is a promising candidate for high-performance supercapacitors.     

Interconnected SnO2/graphene+CNT network as high performance anode materials for lithium-ion batteries

As a metal oxide with a high theoretical capacity, SnO₂ is considered to be one of the promising alternative anode materials in lithium-ion batteries. However, the pulverization of electrodes caused by the large volume expansion of SnO₂ during repeated charge/discharge hinders its practical application. Here, SnO₂ nanoparticles decorated on a 3D carbon network structure formed by the interconnection of graphene and CNT (SnO₂/G + CNT), which is designed and successfully synthesized via in situ chemical synthesis and thermal treatment. In this structure, the SnO₂ with nanosized can increase energy storage points and decrease the ions transport length, the carbon network can build a high conductive network that facilitates electron transport and alleviate the volume expansion to prevent electrode pulverization. In addition, graphene has a high specific surface area effect that facilitates lithium-ion storage, and the CNT also supports the graphene frame to make the carbon skeleton structure more stable, and provides a large number of ion transport channels, increasing the active sites of the reaction. Due to this excellent structure with synergistic effects, the SnO₂/G + CNT electrode exhibits superior reversible capacity (1227.2 mAh g^-1 at 0.1 A g^-1 after 200 cycles), superior rate capacity (549.3 mAh g^-1 at 3.0 A g^-1) and long cycle stability (1630.1 mAh g^-1 at 0.5 A g^-1 after 1000 cycles).     

Encapsulating homogenous ultra-fine SnO2/TiO2 particles into carbon nanofibers through electrospinning as high-performance anodes for lithium-ion batteries

Homogenous ultra-fine SnO₂/TiO₂ particles encapsulated into carbon nanofibers (SnO₂/TiO₂@CNFs) with a uniform and ordered one-dimensional fibrous structure are fabricated through facile electrospinning technique and subsequent heat treatments, which are confirmed by XRD, Raman, TG, SEM, TEM, and XPS analyses. The battery performance reveals that the SnO₂/TiO₂@CNFs-1.5:1 (1.5:1 denotes the mole ratio of SnO₂ to TiO₂ in the carbon nanofibers) electrode displays the optimal electrochemical properties among the whole samples, which can deliver the initial charge and discharge specific capacity of 1061.2 and 1494.8 mAh/g with a coulombic efficiency of 71.0% at 100 mA/g, and exhibit a remarkable specific capacity of 766.1 mAh/g after 200 cycles. Moreover, the SnO₂/TiO₂@CNFs-1.5:1 electrode displays a high pseudocapacitive contribution of 73.9% at the scan rate of 2 mV/s and the lithium ion diffusion coefficient of approximately 1.20 × 10^?15 cm² s^?1. The excellent electrochemical performance of the SnO₂/TiO₂@CNFs-1.5:1 electrode is closely correlated with the synergetic effect of the proper amount of TiO₂ that enhances the electrochemical stability of the electrode and provides fractional capacity, and the flexible and conductive carbon nanofiber matrix that accommodates volume changes and increases overall electronic conductivity. The detailed investigations of the as-prepared electrode materials by a facile electrospinning process may pave possible instructions for the next generation SnO₂-based anodes and other related electrospun anodes for the energy storage device.     

Binder-free carbon-coated TiO2@graphene electrode by using copper foam as current collector as a high-performance anode for lithium ion batteries

Anatase TiO₂ is widely used in lithium ion batteries (LIBs) due to its excellent safety and excellent structural stability. However, due to the poor ion and electron transport and low specific capacity (335 mAh g⁻¹) of TiO₂, its application in LIBs is severely limited. For the first time, we report a binder-free, carbon-coated TiO₂@graphene hybrid by using copper foam as current collector (TG-CM) to enhance the ionic and electronic conductivity and increase the discharge specific capacity of the electrode material without adding conductive carbon (such as super P, etc.) and a binder (such as polyvinylidene fluoride (PVDF), etc.). When serving as an anode material for LIBs, TG-CM displays excellent electrochemical performance in the voltage range of 0.01–3.0 V. Moreover, the TG-CM hybrid delivers a high reversible discharge capacity of 687.8 mAh g⁻¹ at 0.15 A g⁻¹. The excellent electrochemical performance of the TG-CM hybrid is attributed to the increased lithium ion diffusion rate due to the introduction of graphene and amorphous carbon layer, and the increased contact area between the active material and electrolyte, and small resistance with copper foam as the current collector without an additional binder (PVDF) and conductivity carbon (super P).     

FeS@onion-like carbon nanocapsules embedded in amorphous carbon for the lithium ion batteries with excellent cycling stability

The development of lithium ion battery with long-term cycle stability is considered to be a prerequisite for commercialization. Onion-like carbon coated FeS nanocapsules embedded in amorphous carbon (FeS@OLC/a-C) is designed and one-step developed via discharging the Fe-C composite ingot under the atmosphere of Ar and H₂S. In FeS@OLC/a-C nanocomposites, ~ 8.9?nm FeS@OLC nanocapsules with an average onion-like shell of 2?nm are covered by the amorphous carbon. The formation mechanism has been proposed for FeS@OLC/a-C nanocomposites. As the lithium ion battery anode candidate, FeS@OLC/a-C nanocomposite electrode have the advantages of good cycling stability (719.2 mAh g^?1 after being cycled at 0.1?A?g^?1 for 200 times) and excellent high-rate performances (569.3 mAh g^?1 for 2?A?g^?1, 540.9 mAh g^?1 for 4?A?g^?1, 466.6 mAh g^?1 for 8?A?g^?1 and 340.0 mAh g^?1 for 16?A?g^?1), which originates from the combined effect of small FeS nanoparticles, the onion-like carbon layers and amorphous carbon. The design idea in this paper provides a new approach for improving the cycling stability and rate capability of lithium ion battery.     

Spherical clusters of β-Ni(OH)2 nanosheets supported on nickel foam for nickel metal hydride battery

Spherical clusters of Ni(OH)₂ nanosheets are directly grown on skeletons of nickel foam via a facile template-free spontaneous growth method. The obtained electrode (β-Ni(OH)₂/Ni-foam) is characterized by X-ray diffractometry, scanning and transmission electron microscopy and thermal analysis. Results show that Ni(OH)₂ has a β-phase structure and presents on the nickel foam skeleton mostly as spherical clusters with a diameter of ∼10 μm. The spheres are composed of nanosheets with thickness of ∼60 nm, width of ∼230 nm and length up to ∼2 μm, and the nanosheets are assembled by nanoparticles with diameter of ∼20 nm. The electrochemical performance of the β-Ni(OH)₂/Ni-foam electrode is evaluated by cyclic voltammetry and galvanostatic charge–discharge tests. The difference between the oxygen evolution reaction onset potential and the anodic peak potential for this electrode (∼100 mV) is larger than that for β-Ni(OH)₂ nanosheets and nanotubes powder electrode (∼65–77 mV) and much larger than that for commercial spherical β-Ni(OH)₂ powder electrode (∼25–47 mV), indicating that the β-Ni(OH)₂/Ni-foam electrode can be fully charged. The specific discharge capacity of β-Ni(OH)₂ in the β-Ni(OH)₂/Ni-foam electrode reaches 275 mAh g⁻¹, which is close to the theoretical value, lower than that of β-Ni(OH)₂ nanotubes (315 mAh g⁻¹), but higher than that of nanosheets (219.5 mAh g⁻¹), commercial micrometer grade spherical powders (265 mAh g⁻¹) and microtubes (232.4 mAh g⁻¹).     

Molybdenum carbide embedded in carbon nanofiber as a 3D flexible anode with superior stability and high-rate performance for Li-ion batteries

The fabrication process and material design of flexible lithium-ion batteries (LIBs) are essential in flexible portable devices. In particular, the carbon nanofiber (CNF)-based active anodes with flexibility synthesized using an electrospinning technique showed fairly stable cycling performance in the LIBs. In this study, we synthesized the molybdenum carbide (MoC) embedded in CNFs as an anode for LIBs (MoC/CNF) using an electrospinning technique with amorphous Mo precursor and polyacrylonitrile as the molybdenum and carbon sources, respectively, and using a heating process under an N₂ atmosphere. The as-prepared flexible MoC/CNF showed a 3D porous structure consisting of crystalline MoC and amorphous CNF. MoC/CNF, directly utilized as an active electrode without binder, conductor, or current collector, exhibited superior LIB performance, i.e. high capacity, cyclability, and high-rate properties. In particular, at a considerably high charge/discharge rate of 10?A?g^?1, the specific capacity of MoC/CNF (109?mAh?g^?1) was significantly higher than that of pure CNF electrode (3?mAh?g^?1).     

Vertically aligned,polypyrrole encapsulated MoS2/graphene composites for high-rate LIBs anode

Ultrathin MoS₂ nanosheets were vertically anchored on the reduced graphene oxide (MoS₂/rGO) via hydrothermal method. To further engineering the surface conductivity, ultrathin polypyrrol (PPy) layer was coated on the MoS₂/rGO composite via in situ polymerization to form a bi-continuous conductive network with a sandwich-like structure. The graphene nanosheets and the PPy coating can facilitate the electrons transfer rate, while the ultrathin MoS₂ nanosheets can enhance the utilization efficiency of the active materials. The obtained MoS₂/rGO-10 composite exhibits high reversible specific capacity (970?mAh?g^?1 at 0.1?A?g^?1) and rate capability (capacity retention of 64% at 3.2?A?g^?1). Moreover, the PPy@MoS₂/rGO hybrids reveal lower specific capacity but better rate capability, and a “trade-off” effect between electrons and ions transfer resistance was observed. This easy-scalable PPy surface conductivity engineering strategy may be applied in the preparation of high-performance LIBs active materials.     

ZnS nanoparticles embedded in porous honeycomb-like carbon nanosheets as high performance anode material for lithium ion batteries

ZnS nanoparticles coated with honeycomb-like carbon nanosheets (ZnS@HPC) were synthesized via freeze drying and carbonization methods, using NaCl crystals as hard template. The ZnS@HPC composite possessed a novel three-dimensional network structure and high specific surface area of 128.9?m² g^?1. In this composite, ZnS nanoparticles with small diameter of 20–40?nm were embedded in carbon nanosheet matrix. Moreover, nitrogen-doped carbon formed successfully during the carbonization process. The porous carbon matrix provided a conductive network and also worked as a buffer to confine ZnS nanoparticle expansion during lithiation and delithiation process. So, the electrochemical performance of ZnS@HPC composite electrode was much better than that of ZnS and ZnS/C electrodes. As a novel anode material, ZnS@HPC composite exhibited the initial cycle discharge and charge capacities of 1359 and 889?mAh?g^?1 at 100?mA?g^?1; and showed excellent cycle performance, the discharge capacity achieved 408?mAh?g^?1 after cycling at 1?A?g^?1 for 200 cycles.     

Compositing SrLi2Ti6O14 with chemical deposited silver for enhancing lithium ion storage

One of the main issues for titanium-based anode materials is their poor electronic conductivity and this issue can affect their rate performance. For conquering this drawback, many approaches have been proposed. In this report, SrLi₂Ti₆O₁₄ as one of the titanium-based anode materials is prepared via a facile sol–gel method and subsequently it has been composited with silver to elevate its electronic conductivity. Upon the analysis of electrochemical results, the SrLi₂Ti₆O₁₄/Ag composite with 6?wt% Ag can deliver an initial capacity of 164.9?mAh?g^?1. After 50 cycles, the sample can still retain 154.6?mAh?g^?1 with 93.8% retention of the first cycle. Meanwhile, the SrLi₂Ti₆O₁₄/Ag composite with 6?wt% Ag can also exhibit good rate capacities, even at 300?mA?g^?1, its capacity can be firmly kept at 140.0?mAh?g^?1. In addition, in situ X-ray diffraction characterization shows the structural reversibility of the SrLi₂Ti₆O₁₄/Ag composite with 6?wt% Ag during cycling. All the electrochemical results indicate that the SrLi₂Ti₆O₁₄/Ag composite with 6?wt% Ag can be a promising anode material for lithium ion batteries.     

Mn/Co oxide on Ni foam as a bifunctional catalyst for Li–air cells

Binary Mn/Co oxide sheets with spherical flower-like hierarchical structure are grown directly on the surface of a Ni foam skeleton as a cathode for Li–O₂ batteries using a hydrothermal method. This integrated cathode architecture eliminates the negative effects of a conductive carbon additive and binder on the electrochemical performance of Li–O₂ batteries and minimizes the processing steps in fabrication of cathodes for Li–O₂ batteries. The porous Ni foam acts as a scaffold and current collector, and the highly hierarchical porous flower-like structure of the binary Mn/Co oxide sheet acts as a highly active catalyst. Together, they facilitate effective diffusion of oxygen gas as well as rapid ion and electron conduction during electrochemical reactions. When assembled in Li–O₂ cells, the prepared catalyst exhibits excellent catalytic activities, including the oxygen reduction and oxygen evolution reactions. In particular, the Li–O₂ cell using the cathode delivers an extremely high specific discharge capacity of 9690 mAh g^-1 under a applied specific current of 200 mA g^-1 and operate successfully in a long lifespan of 66 cycles even under a high specific current of 600 mA g^-1 and a limited discharge-charge capacity mode of 1000 mAh g^-1. The simultaneous effect of the fast electron transport kinetics provided by the free-standing structure and the high catalytic activity of the binary Mn/Co oxide show promise for use in air electrodes for Li–O₂ batteries.     

Interface bonding engineering for constructing a battery-type supercapacitor cathode with ultralong cycle life and high rate capability

The low rate and poor cycle greatly limit the large-scale applications of supercapacitors electrodes in energy storage field. In this work, the SnS₂/Ni₃S₂ nanosheets arrays are bonded on N/S co-doped graphene nanotubes though N–Sn/Ni and S–Sn/Ni interface bonds employing a simple hydrothermal method to form a self-supported battery-type supercapacitors cathode. A series of characterization and DFT calculations indicate that the interface bonding not only automatically generates the internal electric field and allows more redox reactions to carry out easily, but also effectively reduces the OH^? ions adsorption energy and maintains the integration of the electrode structure. This unique design greatly promotes the electronics/ions transfer and reaction kinetics of the cathode, and substantially enhances its rate capability and durability. Detailedly, a high specific capacity of 296.9 mAh g^?1 at 2 A g^?1 is obtained. More impressively, the cathode still holds 155.6 mAh g^?1 when the current density is enlarged to 100 A g^?1, as well as it can retain 84% initial capacity over 50,000 cycles. Besides, an assembled asymmetric supercapacitor utilizing the prepared N/S-GNTs@B–SnS₂/Ni₃S₂ nanosheets arrays cathode and activated carbon anode presents a large energy density of 51 W h kg^?1 at 850 W kg^?1 and outstanding cycling stability. This work provides an effective strategy for improving rate capability and cycle lifespan of battery-type supercapacitors electrodes, and pushes the metal compounds forward a significant step in the practical applications of energy storage devices.     

Super-thin LiV3O8 nanosheets/graphene sandwich-like nanostructures with ultrahigh lithium ion storage properties

With the thickness less than 5?nm, super-thin LiV₃O₈ nanosheets have already been successfully synthesized by transformation from super-thin V₂O₅·xH₂O nanosheets, moreover, super-thin LiV₃O₈ nanosheets@graphene (LVO/G) sandwich-like layer-by-layer nanostructures were successfully obtained via a facile self-assembly method and annealing treatment. Such interesting LVO/G nanostructures as cathodes for lithium ion batteries not only show high capacity up to 397.2?mA?h?g^?1 and outstanding rate capabilities (171?mA?h?g^?1 at 10?C, 112?mA?h?g^?1 at 15?C), but also present super-long cycle performance (301.2?mA?h?g^?1 after 500 cycles at 1?C). As far as we known, the LVO/G cathodes exhibit ultrahigh lithium storage performances even much higher than those of previously reported literatures of LiV₃O₈, which demonstrates that such sandwich-like layer-by-layer LVO/G nanostructures is a potential candidate cathode material for the next generation of batteries.     

The additive-free electrode based on the layered MnO2 nanoflowers/reduced,graphene oxide film for high performance supercapacitor

The MnO₂ nanoflowers/reduced graphene oxide composite is coated on a nickel foam substrate (denoted as MnO₂ NF/RGO @ Ni foam) via the layer by layer (LBL) self-assembly technology without any polymer additive, following the soft chemical reduction. The layered MnO₂ NF/RGO composite is uniformly anchored on the Ni foam skeleton to form the 3D porous framework, and the interlayers have access to lots of ions channels to improve the electron transfer and diffusion. This special construction of 3D porous structure is beneficial to the enhancement of electrochemical property. The specific capacitance is up to 246 F g⁻¹ under the current density of 0.5 A g⁻¹. After 1000 cycles, it can retain about 93%, exhibiting excellent cycle stability. The electrochemical impedance spectroscopy measurements confirm that MnO₂ NF/RGO @ Ni foam electrode has lower R_ESR and R_CT values when compared to MnO₂ @ Ni foam and RGO @ Ni foam. This study opens a new door to the preparation of composite electrodes for high performance supercapacitor.     

Synthesis of mesoporous SnO2 spheres via self-assembly and superior lithium storage properties

This paper firstly reported a simple route to prepare SnO₂ mesoporous spheres for lithium ion battery. Mesoporous SnO₂ spheres in range of 100–300 nm were prepared by primary reaction at 353 K for 30 min, and calcination process at 773 K, which could be scaled up for manufacturing. The nano-size effect of the small particle and the 3D mesoporous structure promoted the electrolyte and lithium ion transfer and suppressed the volume changes, which greatly enhanced the cycle performances. As the anode material, it could deliver 761 mAh g⁻¹ capacity after 50 cycles at the current density of 200 mA g⁻¹. Even at 2 A g⁻¹, it retained 480 mAh g⁻¹ after 50 cycles. Furthermore, we suggested that the high stability of the structure was responsible for the improved cycle properties.     

An ordered mesoporous network consisting of carbon-coated ultrasmall SnO2 nanoparticles with enhanced Lithium storage

An unique ordered mesoporous network consisting of carbon-coated SnO₂ nanoparticles (NPs) is developed by a facile self-assemble strategy via a solvethermal route in which employs N,N-dimethylformamide/H₂O as mixture solvent and polyvinyl pyrrolidone as barrier agent and carbon source. The SnO₂-NPs with an uniform dimension of ~5 nm are observed to interconnect with each other, and assemble into high-compact blocks where abundant mesopores with an average diameter of ~4 nm are found throughout the body. The carbon coating with a thickness of <1 nm are confirmed to exist on these SnO₂-NPs, which is of great importance to avoid the severe sintering that occurs in the case of bare SnO₂-NPs. Furthermore, the carbon coating plays roles in enhancing conductivity and keeping the active particles from being directly contacted with electrolyte, and thus contributes to enhanced reversible capacity of 949 mAh g⁻¹ and improved initial Coulombic efficiency. The composite electrode with a high tap density of 2.0 g cm⁻³ exhibits substantially elevated electrochemical performances, such as a charge capacity of 565 mAh g⁻¹ vs 223 mAh g⁻¹ of common SnO₂-NPs after 60 cycles and greatly improved rate capability, indicating the promising applications of this advanced micro-nano architecture for next-generation lithium-ion batteries.