Lishuang Fan

Graphene Aerogels with Anchored Sub‐Micrometer Mulberry‐Like ZnO Particles for High‐Rate and Long‐Cycle Anode Materials in Lithium Ion Batteries

Graphene aerogels (GAs) anchoring hierarchical, mulberry-like ZnO particles are fabricated in situ using a one-step solvothermal reaction. The resulting composites can function as anodes in lithium ion batteries, where they exhibit a high capacity and cyclic stability. The reversible capacities obtained are 365, 320, and 230 mA h g-1 at current densities of 1, 2, and 10 A g-1 . Their high reversible capacity is 445 mA h g-1 at a current density of 1.6 A g-1 ; this value is maintained even after the 500th cycle, The excellent electrochemical performance is attributed to strong oxygen bridges between ZnO and graphene, where C-O-Zn linkages provide a good pathway for electron transport during charge/discharge cycles. Additionally, the hierarchical structure of the ZnO microballs suppresses stacking among the graphene layers, allowing the GAs to accelerate the transport of lithium ions. Furthermore, the GA framework enhances the electrical conductivity and buffer any volume expansion.

Carbon Nanohorns Carried Iron Fluoride Nanocomposite with ultrahigh rate lithium ion storage properties

Novel hierarchical carbon nanohorns (CNHs) carried iron fluoride nanocomposites have been constructed by direct growth of FeF3·0.33H2O nanoparticles on CNHs. In the FeF3·0.33H2O@CNHs nanocomposite, the mesopore CNHs play the role as conductive matrix and robust carrier to support the FeF3·0.33H2O nanoparticles. The intimate conductive contact between the two components can build up an express way of electron transfer for rapid Li+ insertion/extraction. The CNHs can not only suppress the growth and agglomeration of FeF3·0.33H2O during the crystallization process, but also sever as an “elastic confinement” to support FeF3·0.33H2O. As was to be expected, the hierarchical FeF3·0.33H2O@CNHs nanocomposite exhibits impressive rate capability and excellent cycle performance. Markedly, the nanocomposite proves stable, ultrahigh rate lithium ion storage properties of 81 mAh g−1 at charge/discharge rate of 50 C (a discharge/charge process only takes 72 s). The integration of high electron conductivity, confined nano sized FeF3·0.33H2O (~5 nm), hierarchical mesopores CNHs and the “elastic confinement” support, the FeF3·0.33H2O@CNHs nanocomposite demonstrates excellent ultrahigh rate capability and good cycling properties.

Ultra-high rate Li–S batteries based on a novel conductive Ni2P yolk–shell material as the host for the S cathode

Sulfur cathodes have attracted significant attention as the next generation electrode material candidate due to their considerable theoretical energy density. The main challenge in developing long-life and high-power Li–S batteries is simultaneously suppressing the shuttle effect and reinforcing the reaction kinetics. In this work, we have designed novel nickel phosphide (Ni2P) yolk–shell nanosphere encapsulated sulfur (S@Ni2P-YS) for lithium–sulfur batteries with high power character. Conductive polar Ni2P has been shown to integrate the adsorption site and the electrochemical active site of polysulfides, which has been proven to increase the intrinsic activity toward in situ electrochemical reaction during the reaction process compared to semiconducting nickel oxides. Consequently, S@Ni2P-YS exhibits an enhanced performance of 1409 mA h g−1 initially at 0.2C (1C = 1675 mA g−1) and 439 mA h g−1 at 10C. Meanwhile, high cycle life has been achieved (645 mA h g−1 initially and 394 mA h g−1 after 1000 cycles at a current density of 5C) attributed to the high chemical adsorption ability. This class of conductive Ni2P composite and its electrochemical behavior could provide novel insights for high-energy batteries.

Hierarchical mesoporous SnO2 nanosheets on carbon cloth toward enhancing the polysulfides redox for lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries have been acknowledged as outstanding substitutes for energy storage systems due to their superiority in energy density. To satisfy the commercial applications, its necessary to establish the highly efficient and long-life Li–S batteries by synchronously restraining the shuttle effect and enhancing the polysulfides redox. Here, we prepared hierarchical mesoporous SnO2 nanosheets on carbon nanofibers (CNFs) namely C@SnO2 with the novel topological method. The obtained C@SnO2 materials not only show the strong chemisorption to trap polysulfides but also can more effectively decrease the electrochemical polarization to enhance the polysulfides redox. With the 3D conductive framework CNFs as the current collector, the hierarchical C@SnO2/S nanosheets material electrode delivered a specific capacity of 1228 mA h g−1 at 0.2C and retained a stable cycling performance at 2C over 1000 cycles with the decay as low as ≈0.024% per cycle.

Long-Life Lithium–Sulfur Battery Derived from Nori-Based Nitrogen and Oxygen Dual-Doped 3D Hierarchical Biochar

Due to restrictions on the low conductivity of sulfur and soluble polysulfides during discharge, lithium sulfur batteries are unsuitable for further large scale applications. The current carbon based cathodes suffer from poor cycle stability and high cost. Recently, heteroatom doped carbons have been considered as a settlement to enhance the performance of lithium sulfur batteries. With this strategy, we report the low cost activated nori based N,O-doped 3D hierarchical carbon material (ANC) as a sulfur host. The N,O dual-doped ANC reveals an elevated electrochemical performance, which exhibits not only a good rate performance over 5 C, but also a high sulfur content of 81.2%. Further importantly, the ANC represents an excellent cycling stability, the cathode reserves a capacity of 618 mAh/g at 2 C after 1000 cycles, which shows a 0.022% capacity decay per cycle.

Kinetics enhancement of lithium–sulfur batteries by interlinked hollow MoO2 sphere/nitrogen-doped graphene composite

The shuttle effect and poor redox kinetics are vital issues restricting the evolution of lithium sulfur batteries; it is therefore exigent to rationally design an effective sulfur host. Hence, this paper reports a hollow MoO2 sphere anchored on nitrogen-doped graphene. The hollow MoO2 sphere controls the polysulfide dissolution, and the nitrogen-doped graphene provides a conductive network and high sulfur loading. Meanwhile, the C–O–Mo bond interlinking MoO2 and N-doped graphene provides a pathway for electron transfer, and the synergistic effect enhances the kinetics of lithium sulfur batteries profitably. Ascribed to the unique structure of MoO2/nitrogen-doped graphene, the obtained electrode exhibits a substantially enhanced electrochemical performance.

In-situ synthesis of CuCo2S4@N/S doped graphene composites with pseudocapacitive properties for high performance lithium ion batteries

To satisfy the demand of high power application, lithium-ion batteries (LIBs) with high power density have gained extensive research effort. The pseudocapacitive storage of LIBs is considered to offer high power density through fast faradic surface redox reactions rather than the slow diffusion-controlled intercalation process. In this work, CuCo2S4 anchored on N/S-doped graphene is in situ synthesized and a typical pseudocapacitive storage behavior is demonstrated when applied in the LIB anode. The pseudocapacitive storage and N/S-doped graphene enable the composite to display a capacity of 453 mA h g-1 after 500 cycles at 2 A g-1 and a ultrahigh rate capability of 328 mA h g-1 at 20 A g-1. We believe that this work could further promote the research on pseudocapacitive storage in transition-metal sulfides for LIBs.

Recovering energy from dye wastewater for a new kind of superior supercapacitor material

Utilizing waste for harnessing energy is considered to be a sustainable approach to recompense the energy crisis. Herein, we report an easy and green method to remove a dye through adsorption on the surface of graphene. These nanostructured methylene blue/graphene (MB/G) materials are used for the investigation of electrochemical behaviours. The MB/G is found to demonstrate a specific capacitance of 185 F g−1 at 1 A g−1, which is almost four times higher than that of pure graphene (57 F g−1). Interestingly, the capacitance retention ratio remains high, at over 98.7% after 800 cycles.

Achieving rough sphere-shaped ZnS with superior attenuation electromagnetic absorption performance

ZnS micrometer spheres were prepared via a facile hydrothermal route. Polyvinyl pyrrolidone (PVP) was used as the surfactant. By controlling the PVP content, the smooth surface of ZnS sphere was converted to a rough surface, which led to a stronger electromagnetic wave scattering intensity when used as an electromagnetic absorption absorber. ZnS microspheres with the roughest surface showed the best electromagnetic absorption property. The absorption frequency of this product at 2.0 mm was 4.2 GHz. The minimum reflection loss was nearly −35.0 dB, indicating excellent attenuation ability. The attenuation mechanism is discussed in detail and was attributed to the scattering effect.

The facile preparation of a carbon coated Bi2O3 nanoparticle/nitrogen-doped reduced graphene oxide hybrid as a high-performance anode material for lithium-ion batteries

A hybrid of carbon coated Bi2O3 nanoparticles distributed on nitrogen-doped reduced graphene oxide is prepared by facile thermal treatment processes. In this hybrid electrode material, the nitrogen-doped reduced graphene oxide improves the electron and Li+ transport due to its good electrical conductivity and surface wettability. In addition, the carbon coating layer avoids direct contact between the Bi2O3 and electrolyte, so it effectively inhibits the repeated formation and decomposition of a solid electrolyte interface film. Furthermore, Bi2O3 nanoparticles can improve the Li+ diffusion because of the short Li+ diffusion distance. As a result, the hybrid has stable cycling retention (391 mA h g−1 after 250 cycles at 3 A g−1), and outstanding rate capability (326 mA h g−1 at 4.8 A g−1). The excellent electrochemical performance is associated with the synergistic effect of the highly conductive nitrogen-doped reduced graphene oxide matrix and carbon coating layer. The excellent lithium storage capability indicates that the hybrid of carbon coated Bi2O3 nanoparticles distributed on nitrogen-doped reduced graphene oxide has significant potential as an anode for lithium-ion batteries.