Sangui Liu

Facile Synthesis of Novel Networked Ultralong Cobalt Sulfide Nanotubes and Its Application in Supercapacitors

Ultralong cobalt sulfide (CoS(1.097)) nanotube networks are synthesized by a simple one-step solvothermal method without any surfactant or template. A possible formation mechanism for the growth processes is proposed. Owing to the hollow structure and large specific area, the novel CoS(1.097) materials present outstanding electrochemical properties. Electrochemical measurements for supercapacitors show that the as-prepared ultralong CoS(1.097) nanotube networks exhibit high specific capacity, good capacity retention, and excellent Coulombic efficiency.

Solvent-mediated directionally self-assembling MoS2 nanosheets into a novel worm-like structure and its application in sodium batteries

Ultralong worm-like MoS2 nanostructures were assembled with a solvent-mediated solvothermal process by controlling the composition ratio of the miscible precursors in solution. The formation mechanism of worm-like MoS2 nanostructures was proposed and the as-prepared materials as anodes in sodium ion batteries delivered a good discharge–charge capacity, superior cycling stability and excellent coulombic efficiency. This work provides an efficient and economic approach to tailor the nanostructure of layered transition metal oxides and transition-metal dichalcogenides simply by controlling the chemical composition and physical properties in a solvothermal process.

Na3.12Fe2.44(P2O7)2/multi-walled carbon nanotube composite as a cathode material for sodium-ion batteries

Na3.12Fe2.44(P2O7)2/multi-walled carbon nanotube (MWCNT) composite was fabricated by a solid state reaction and was further used to fabricate a cathode for sodium-ion batteries. The electrochemical behaviors were thoroughly investigated in assembled non-aqueous Na3.12Fe2.44(P2O7)2/MWCNT//Na cells, showing higher specific capacity (over 100 mA h g−1 at a rate of 0.15C) and better stable cycle performance than those of the pristine Na3.12Fe2.44(P2O7)2-based one. It is noted that with increased charge–discharge cycles, the specific capacity of Na3.12Fe2.44(P2O7)2/MWCNT gets close to the theoretical capacity (ca. 117.4 mA h g−1). These good performances could be attributed to the incorporated MWCNTs, which improve the conductivity for lower charge transfer resistance and shorten the diffusion length for faster Na+ diffusion to access the reaction sites. Through systematic studies of EIS at different states of charge and discharge, it is discovered that Rct decreases with the increase of voltage and reaches a minimum value at redox sites, but Re and DNa+ show the opposite trend. Moreover, a full cell test using a carbon black negative electrode also demonstrates good capacity retention up to 50 cycles and a reversible capacity of 145 mA h g−1 with the average operation voltage of 2.8 V.

Fabrication of CeO2 nanoparticle-modified silk for UV protection and antibacterial applications.

To endow silk with UV-shielding ability and antibacterial activity, CeO2 nanoparticles were immobilized on silk surface via a dip-coating approach without changing silk structure. Surface density of the nanoparticles could be easily adjusted by controlling the number of dip-coating cycle. Enhanced thermal stability of the modified silk is exhibited in thermogravimetric analysis (TGA) and derivative thermogravimetric analysis (DTG). The excellent UV-protection ability and antibacterial property of the CeO2 nanoparticle-coated silk are demonstrated in UV-vis diffuse reflectance spectroscopy and colony-forming capability test, respectively. Based on the data, it can be concluded that CeO2 nanoparticles could be used as a very promising coating material to modify silk for UV-protection and antibacterial applications.

Aspergillus flavus Conidia-derived Carbon/Sulfur Composite as a Cathode Material for High Performance Lithium–Sulfur Battery

A novel approach was developed to prepare porous carbon materials with an extremely high surface area of 2459.6 m2g−1 by using Aspergillus flavus conidia as precursors. The porous carbon serves as a superior cathode material to anchor sulfur due to its uniform and tortuous morphology, enabling high capacity and good cycle lifetime in lithium sulfur-batteries. Under a current rate of 0.2 C, the carbon-sulfur composites with 56.7 wt% sulfur loading deliver an initial capacity of 1625 mAh g−1, which is almost equal to the theoretical capacity of sulfur. The good performance may be ascribed to excellent electronic networks constructed by the high-surface-area carbon species. Moreover, the semi-closed architecture of derived carbons can effectively retard the polysulfides dissolution during charge/discharge, resulting in a capacity of 940 mAh g−1 after 120 charge/discharge cycles.

Fabrication of WS2-nanoflowers@rGO composite as an anode material for enhanced electrode performance in lithium-ion batteries

In this paper, we descried a simple method to fabricate three-dimensional (3D) composite materials, WS2-nanoflowers @ reduced graphene oxide (WS2-NF@rGO), in which rGO crossed-link the isolated WS2-NF to construct a 3D conductive network and provided protection against the volume changes of WS2 during electrochemical processes simultaneously. This unique structure of the WS2-NF@rGO composite could not only promote both ion and electron diffusion, but also enhance the electrode stability, thus obtaining a high-capacity and long-cycle anode material for lithium-ion batteries. As a result, the WS2-NF@rGO exhibited a reversible capacity of 730mAhg-1 after 150 cycles at 100mAg-1 and maintained a capacity of higher than 260mAhg-1 at 2Ag-1, thus exhibiting great potential as an anode material for lithium storage.

A selenium-confined porous carbon cathode from silk cocoons for Li–Se battery applications

A composite of selenium (Se) and a rich porous carbon material (PCM) with mesopores from silk cocoons is explored as a cathode for lithium–selenium (Li–Se) batteries for the first time. Elemental selenium is homogeneously dispersed inside the mesopores of the PCM by a melt-diffusion method based on several analyses. The synthetic PCM/Se composite can effectively suppress the dissolution of the active material and maintain mechanical stability. In the case of Li–Se batteries, it delivers a reversible capacity of more than 230 mA h g−1 after 510 cycles at 2C. The remarkable electrochemical performance may benefit from the favorable conductivity and the porous structure of the carbon material as the host matrix.

Synthesis of novel book-like K0.23V2O5 crystals and their electrochemical behavior in lithium batteries

A novel book-like K0.23V2O5 crystal is obtained by a simple hydrothermal method and is explored as a cathode material for Li-ion batteries for the first time. It exhibits a high reversible capacity (of ca. 244 mA h g(-1) at a current density of 50 mA g(-1)), along with a good rate capability (80 mA h g(-1) at a current density of 1800 mA g(-1)) and a good capacity retention (185.3 mA h g(-1) after 100 cycles).

Porous carbon derived from Sunflower as a host matrix for ultra-stable lithium–selenium battery

A novel porous carbon material using the spongy tissue of sunflower as raw material is reported for the first time. The obtained porous carbon has an extremely high surface area of 2493.0m2g-1, which is beneficial to focus on encapsulating selenium in it and have an inhibiting effect about diffusion of polyselenides over the charge/discharge processes used as the host matrix for Li-Se battery. The porous carbon/Se composite electrode with 63wt% selenium delivers a high specific capacitance of 319mAhg-1 of the initial capacity, and maintains 290mAhg-1, representing an extremely high capacity retention of 90.9% after 840 cycles with the rate of 1C.

NaTi3FeO8: a novel anode material for sodium-ion batteries

A novel NaTi3FeO8 material is explored as an anode for sodium-ion batteries for the first time. It delivers a reversible discharge capacity of 170.7 mA h g−1 at 20 mA g−1 in a sodium half cell, exhibiting good capacity retention at a cut-off voltage of 0.01–3 V.