A novel electrochemical activation effect induced morphology variation from massif-like CuxO to forest-like Cu2O nanostructure and the excellent electrochemical performance as anode for Li-ion battery

Monodispersed Copper Phosphide Nanocrystals in situ Grown into Nitrogen-doped Reduced Graphene Oxide Matrix and their Superior Performance as the Anode for Lithium-ion Batteries

A nanocomposite anode material consisting fully of monodispersed copper phosphide (Cu3P) nanocrystals in situ grown into three dimensional (3D) nitrogen-doped reduced graphene oxide (N-RGO) matrixes has been manufactured in the...

The dependence of Cu2O morphology on different surfactants and its application for non-enzymatic glucose detection

Herein, the Cu₂O yolk-shell nanospheres, nanocubes and microcubes were successfully prepared by a simple seed-medium process. The formation of the Cu₂O yolk-shell nanospheres can be attributed to the self-assembly process caused by the introduction of the seed medium. The formation mechanism of our obtained Cu₂O yolk-shell nanospheres and the dependence of Cu₂O morphology on different surfactants have been studied. The obtained samples were applied in the field of non-enzymatic glucose detection. The electrochemical response characteristics of the modified electrodes toward glucose were investigated by cyclic voltammetry (CV) and chronoamperometry (CA). The electrode modified with C-Cu₂O (obtained by using CTAB as surfactant) shared the highest sensitivity of 3123 μAmM^-1 cm^-2, whereas, the electrode modified with S-Cu₂O (obtained by using SDBS as surfactant) exhibited the lowest LOD of 0.87 μM and the widest linear range of 0.05-10.65 mM. All obtained sensors showed fast response to the addition of glucose. The obtained electrodes showed better responses to glucose than other coexisting interferences, indicating that the obtained electrodes had the acceptable selectivity to glucose. In addition, the stability for 5 consecutive weeks had also been studied and exhibited satisfactory results. The obtained electrode was also used to detect the glucose content in real serum. The acceptable selectivity, stability together with the excellent sensing ability in real serum make the obtained electrodes a potential for practical applications.

Synthesis of a three-dimensional cross-linked Ni-V2O5 nanomaterial in an ionic liquid for lithium-ion batteries

A three-dimensional cross-linked Ni-V₂O₅ nanomaterial with a particle size of 250-300 nm was successfully prepared in a 1-butyl-3-methylimidazole bromide ionic liquid (IL). The formation of this structure may follow the rule of dissolution-recrystallization and the ionic liquid, as both a dissolution and structure-directing agent, plays an important role in the formation of the material. After calcination of the precursor, the active material (Ni-V₂O₅-IL) was used as an anode for lithium-ion batteries. The designed anode exhibited excellent electrochemical performance with 765 mA h g^-1 at a current density of 0.3 A g^-1 after 300 cycles, which is much higher than that of a NiVO-W material prepared via a hydrothermal method (305 mA h g^-1). These results show the remarkable superiority of this novel electrode material synthesized in an ionic liquid.

Lithium-Ion-Based Electrochemical Energy Storage in a Layered Vanadium Formate Coordination Polymer

A vanadium formate (VF) coordination polymer and its composite with partially reduced graphene oxide (prGO), namely VF-prGO, can be applied as anode materials for Li-ion based electrochemical energy storage (EcES) systems in the potential range of 0-3 V (vs Li⁺ /Li). This study shows that a reversible capacity of 329 mAh g^-1 at a current density of 50 mA g^-1 after 50 cycles can be realized for VF along with a high rate capability. The composite exhibits even a higher capacity of 504 mAh g^-1 at 50 mA g^-1 . A good capacity retention is observed even after 140 cycles for both VF and the composite. An ex-situ X-ray photoelectron spectroscopy study indicates the involvement of V³⁺ /V⁴⁺ redox couple in the charge storage mechanism. A significant contribution of this reversible capacity is attributed to the pseudocapacitive behavior of the system.

Fast-Charging High-Energy Battery-Supercapacitor Hybrid: Anodic Reduced Graphene Oxide-Vanadium(IV) Oxide Sheet-on-Sheet Heterostructure

The battery-supercapacitor hybrid (BSH) device has potential applications in energy storage and can be a remedy for low-power batteries and low-energy supercapacitors. Although several studies have investigated electrode materials (particularly for a battery-type anode material) and design for BSHs, the energy density and power density are insufficient (far from the levels required for practical applications). Herein, a hierarchical vanadium(IV) oxide on reduced graphene oxide (rGO@VO₂) heterostructure as an anode and activated carbon on carbon cloth (AC@CC) as a cathode are proposed for fabricating an advanced BSH. The mixed valency of V ions inside the as-prepared VO₂ matrix (V³⁺ and V⁴⁺) facilitates redox reactions at a low potential, giving rise to rGO@VO₂ as a typical anode with a working potential of 0.01-3 V (vs Li/Li⁺). The sheet-on-sheet heterostructured rGO@VO₂ yields a high specific capacity of 1214 mAh g^-1 at 0.1 A g^-1 after 120 cycles, with a high rate capability and stability. The rGO@VO₂//AC@CC BSH device exhibits a maximum gravimetric energy density of 126.7 Wh kg^-1 and a maximum gravimetric power density of ∼10 000 W kg^-1 within a working voltage range of 1-4 V. Moreover, it exhibits fast charging times of 5 and 834 s with energy densities of 15.6 and 82 Wh kg ^-1, respectively.

Mechanistic insights into the phenomena of increasing capacity with cycle number: using pulsed-laser deposited MoO2thin film electrodes

Thin film electrodes often feature fluctuations in capacity with cycle number. This work shows how electrode reactions and peeling off the current collector is a plausible mechanism for these fluctuations.

Copper sulfide nanoparticles as high-performance cathode materials for magnesium secondary batteries

Magnesium secondary batteries are promising candidates for large-scale energy storage systems with high safety, because of the dendrite-free electrodeposition of the magnesium anode. However, the search for available cathode materials remains a significant challenge, hindering their development. In this work, we report copper sulfide nanoparticles as high-performance cathode materials for magnesium secondary batteries, which deliver a high reversible capacity of 175 mA h g-1 at 50 mA g-1. The cathode also shows an excellent rate capability providing 90 mA h g-1 at 1000 mA g-1 and an outstanding long-term cyclability over 350 cycles. The beneficial properties are ascribed to the small-sized copper sulfide particles which facilitate the solid-state diffusion kinetics. Further investigation on the mechanism demonstrates that the reaction is a typical conversion reaction, and the excellent cycling stability is due to the CuS nanoparticles which are not facile to aggregate during cycling. This work introduces an abundant, low-cost and high-performance cathode material for magnesium secondary batteries, and provides feasibility for the practical application of magnesium secondary battery systems in large-scale energy storage devices.

Si/Ag/C Nanohybrids with in Situ Incorporation of Super-Small Silver Nanoparticles: Tiny Amount, Huge Impact

Silicon (Si) has been regarded as one of the most promising anodes for next-generation lithium-ion batteries (LIBs) due to its exceptional capacity, appropriate voltage profile, and reliable operation safety. However, poor cyclic stability and moderate rate performance have been critical drawbacks to hamper the practical application of Si-based anodes. It has been one of the central issues to develop new strategies to improve the cyclic and rate performance of the Si-based lithium-ion battery anodes. In this work, super-small metal nanoparticles (2.9 nm in diameter) are in situ synthesized and homogeneously embedded in the in situ formed nitrogen-doped carbon matrix, as demonstrated by the Si/Ag/C nanohybrid, where epoxy resin monomers are used as solvent and carbon source. With tiny amount of silver (2.59% by mass), the Si/Ag/C nanohybrid exhibits superior rate performance compared to the bare Si/C sample. Systematic structure characterization and electrochemical performance tests of the Si/Ag/C nanohybrids have been performed. The mechanism for the enhanced rate performance is investigated and elaborated. The temperature-dependent I-V behavior of the Si/Ag/C nanohybrids with tuned silver contents is measured. Based on the model, it is found that the super-small silver nanoparticles mainly increase charge carrier mobility instead of the charge carrier density in the Si/Ag/C nanohybrids. The evaluation of the total electron transportation length provided by the silver nanoparticles within the electrode also suggests significantly enhanced charge carrier mobility. The existence of tremendous amounts of super-small silver nanoparticles with excellent mechanical properties also contributes to the slightly improved cyclic stability compared to that of simple Si/C anodes.

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%.

Advances in the Application of Silicon and Germanium Nanowires for High-Performance Lithium-Ion Batteries

Li-alloying materials such as Si and Ge nanowires have emerged as the forerunners to replace the current, relatively low-capacity carbonaceous based Li-ion anodes. Since the initial report of binder-free nanowire electrodes, a vast body of research has been carried out in which the performance and cycle life has significantly progressed. The study of such electrodes has provided invaluable insights into the cycling behavior of Si and Ge, as the effects of repeated lithiation/delithiation on the material can be observed without interference from conductive additives or binders. Here, some of the key developments in this area are looked at, focusing on the problems encountered by Li-alloying electrodes in general (e.g., pulverization, loss of contact with current collector etc.) and how the study of nanowire electrodes has overcome these issues. Some key nanowire studies that have elucidated the consequences of the alloying/dealloying process on the morphology of Si and Ge are also considered, in particular looking at the impact that effects such as pore formation and lithium-assisted welding have on performance. Finally, the challenges for the practical implementation of nanowire anodes within the context of the current understanding of such systems are discussed.

Facile synthesis of a nickel vanadate/Ni composite and its electrochemical performance as an anode for lithium ion batteries

Ni₃V₂O₈/Ni composites are synthesized by a simple hydrothermal route, and show high-rate capability and outstanding long-life cycling stability as a new anode material for Li-ion batteries.

The charge/discharge mechanism and electrochemical performance of CuV2O6 as a new anode material for Li-ion batteries

CuV₂O₆/NG is demonstrated to be a new ideal anode material for Li-ion batteries.

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

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

Morphology-dependent performance of CuO anodes via facile and controllable synthesis for lithium-ion batteries

Nanostructured CuO anode materials with controllable morphologies have been successfully synthesized via a facile and environmentally friendly approach in the absence of any toxic surfactants or templates. In particular, leaf-like CuO, oatmeal-like CuO, and hollow-spherical CuO were obtained by changing the ligand agents. The structures and electrochemical performance of these as-prepared CuO were fully characterized by various techniques, and the properties were found to be strongly dependent on morphology. As anode materials for lithium-ion batteries, the leaf-like CuO and oatmeal-like CuO electrodes exhibit relatively high reversible capacities, whereas hollow-spherical CuO shows enhanced reversible capacity after initial degradation. Furthermore, an excellent high rate capability was obtained for the leaf-like CuO and hollow-spherical CuO electrodes. These results may provide valuable insights for the development of nanostructured anodes for next-generation high-performance lithium-ion batteries.