Yanxiao Chen

Preparation of sodium trimetaphosphate and its application as an additive agent in a novel polyvinylidene fluoride based gel polymer electrolyte in lithium sulfur batteries

Six-membered cyclic sodium trimetaphosphate with strong electronegativity and an excellent capability of chelating metal cations was prepared via a convenient calcining method and used as an additive agent in a PVDF-based gel polymer electrolyte membrane for lithium sulfur batteries after being ion-exchanged with Li+ cations. The membrane and its application in lithium sulfur batteries were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TG), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), linear sweep voltammetry (LSV), charge–discharge test, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Results show that this novel gel polymer electrolyte exhibits a high ionic conductivity of 2–4 mS cm−1 between 17 and 76 °C and has promising characteristics for use in lithium sulfur batteries. The “shuttle effect”, which is the critical issue for lithium sulfur batteries, is restrained because of using the gel polymer electrolyte with the trimetaphosphate added to it.

Preparation of carbon aerogel by ambient pressure drying and its application in lithium/sulfur battery

Formaldehyde, resorcinol, and sodium acetate were used to synthesize the carbon aerogels by ambient pressure drying. The effect of the ratio of resorcinol and sodium acetate for carbon aerogels was researched by scanning electron microscope and Brunauer-Emmett-Teller characterizations. Then the carbon aerogels were applied in synthesizing sulfur/carbon aerogel composites through a melting method, the specific capacity and cycle performance of lithium/sulfur batteries that adopted the prepared composites as cathodes were measured by galvanostatic discharge–charge. X-ray diffraction, conductivity measurement, cyclic voltammetry, and electrochemical impedance spectra tests were also carried out to help explain the electrochemical performance. Finally, the carbon aerogel with the best properties was chosen for the comparative study of replacement of water by acetone as solvent in the preparation of carbon aerogels. According to our study, the carbon aerogel prepared by ambient pressure drying with high electrical conductivity, controllable pore structure, and high specific surface area was proposed to be used for lithium/sulfur batteries, and the key factors to the performance of carbon aerogel/sulfur composites were discussed.

A functional binder–sulfonated poly(ether ether ketone) for sulfur cathode of Li–S batteries

Sulfonated poly(ether ether ketone) (SPEEK) with strong electronegativity and adhesion ability of S/C compounds was prepared by a homogeneous reaction as the binder for the sulfur cathode of Li–S batteries compared to the conventional polyvinylidene fluoride (PVDF) binder. The binder and its applications to lithium sulfur batteries were characterized by proton nuclear magnetic resonance (1H NMR) spectroscopy, Fourier transformation infrared spectroscopy (FT-IR), thermogravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammogram (CV) and charge–discharge tests. The results show that this functional binder exhibits promising characteristics for lithium sulfur batteries with a capacity of 552.6 mA h g−1 at a current density of 1600 mA g−1 and 268.5 mA h g−1 at 1000 mA g−1 after 300 cycles.