Experimental study on the mechanical and electrochemical properties of aqueous emulsifiable diphenylmethane diisocyanate-modified silicon-carbon composite electrodes.

Aqueous emulsifiable diphenylmethane diisocyanate (EMDI) can form strong chemical bonds with aqueous adhesives due to the large number of isocyanate (-NCO) groups, which can enhance the mechanical performance of the adhesives. Currently, sodium carboxymethyl cellulose (CMC)-styrene butadiene rubber (SBR) emulsion aqueous bonding agents are widely used in the preparation of anode materials for lithium-ion batteries (LIBs). In this study, EMDI was added to a porous silicon-carbon composite electrode prepared from CMC-SBR, and the evolution of the mechanical properties of the electrode with the EMDI content was first investigated via quasi-static uniaxial tensile and interfacial strength tests. Subsequently, the effect of the EMDI content on the electrochemical properties of the electrodes was analysed by electrochemical impedance spectroscopy (EIS) and constant-current (CC) charge/discharge performance tests. Finally, material characterisation of the electrodes was carried out by Fourier transform infrared (FTIR) spectroscopy and specific surface area (Brunauer-Emmett-Teller (BET)) analysis. The results show that the addition of EMDI with a mass ratio of 10-20% to the CMC-SBR binder can enhance the mechanical performance of the active layer and the interfacial performance between the active layer and the current collector of the silicon-carbon composite electrode; simultaneously, EMDI can significantly reduce the electrochemical impedance of the electrode material and improve the capacity retention of the electrode. This study provides a new solution for modifying silicon-carbon composite electrodes and promotes the development of high-performance silicon-carbon electrodes.

Oxidized Starch-Reinforced Aqueous Polymer Isocyanate Cured with High-Frequency Heating.

In this research, an oxidized starch/styrene-butadiene rubber system with high capability of absorbing electromagnetic energy was adopted as the main component, the effect of oxidized starch content on the bonding and mechanical properties of aqueous polymer isocyanate (API) after high-frequency curing was evaluated, and the effect mechanisms were explored by combining thermodynamic tests and material characterization methods. Our findings revealed that the addition of oxidized starch enhanced the mechanical properties of API after high-frequency curing and the increase in the amount of oxidized starch enhanced the improvement effect of high-frequency curing on API bonding and mechanical properties. At 5 wt% oxidized starch, high-frequency curing improved API bonding properties by 18.0% and 17.3% under ambient conditions and after boiling water aging, respectively. An increase in oxidized starch content to 25 wt% increased enhancement to 25.1% and 26.4% for the above conditions, respectively. The enhancement effects of tensile strength and Young's modulus of the API adhesive body were increased from 9.4% and 18.2% to 18.7% and 22.6%, respectively. The potential enhancement mechanism could be that oxidized starch could increase the dielectric loss of API, converting more electromagnetic energy into thermal energy creating more cross-linked structures.

Investigation on the mechanical integrity of a PEO-based polymer electrolyte in all-solid-state lithium batteries.

Polyethylene oxide (PEO)-based solid polymer electrolytes (SPEs) have good ionic conductivity and flexibility, and is a key component of all-solid-state lithium batteries (ASSLBs). Therefore, the mechanical integrity of PEO-based SPEs during cell operation needs to be urgently evaluated. Here, we conducted a series of tensile and shear adhesion performance tests on PEO16-LiTFSI electrolyte and LiFePO4 electrode adhesion samples at various temperatures and quenching rates. Based on the interface performance data and the elastic-viscoplastic material model of the PEO-LiTFSI electrolyte, a comprehensive electrochemical-mechanical model was established to analyze the stress in the cell and evaluate the mechanical integrity of the PEO16-LiTFSI electrolyte and SPE/cathode interface. The experimental results show that the adhesion strength of the SPE and cathode decreases significantly with increasing operating temperature and quenching rate. The simulation study indicates that the mechanical properties of the SPE can be fully utilized to a certain extent by increasing the quenching rate. In addition, appropriately increasing the operating temperature helps maintain the mechanical integrity of the SPE during cell operation. However, increasing the quenching rate and operating temperature will reduce the interface bonding properties between the SPE and the cathode, resulting in an increased probability of mechanical failure at the SPE/cathode interface. To suppress this negative effect, a design scheme to maintain the structural integrity of the PEO-based polymer electrolyte is proposed by using the C-rate and the SPE thickness as control parameters, which can assist in engineering design and safe operation of Li/PEO16-LiTFSI/LiFePO4 for ASSLBs.

Studies on the metabolism of 4-methylpiperazine-1-carbodithioc acid 3-cyano-3,3- diphenylpropyl ester hydrochloride in rat bile by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry.

4-Methylpiperazine-1-carbodithioc acid 3-cyano-3,3-diphenylpropyl ester hydrochloride (TM208) is a newly synthesized compound which has shown excellent in vivo and in vitro anticancer activity and low toxicity. In the present study, the major metabolites of TM208 in rat bile were studied by high-performance liquid chromatography/tandem mass spectrometry with an electrospray ionization (ESI) interface. It was demonstrated that TM208 was extensively metabolized in rat bile and nine metabolites (M1-M9) were definitely or tentatively identified: (2-aminoethyl)dithiocarbamic acid 3-cyano-3,3-diphenylpropyl ester (M1), (2-methylaminoethyl)dithiocarbamic acid 3-cyano-3,3-diphenylpropyl ester (M2), 4-[(4-methylpiperazin-1-yl)thioxomethanesulfinyl]-2,2-diphenylbutyronitrile (M3), 4-methylpiperazine-1-carbodithioic acid 3-cyano-3-(4-hydroxyphenyl)-3-phenylpropyl ester(M4), the sulfine of (4-methylpiperazine-1-carbodithioc acid 3-cyano-3,3-diphenylpropyl ester) (M5), 4-methylpiperazine-1-carbothioic acid S-(3-cyano-3,3-diphenylpropyl) ester (M6), piperazine-1-carbodithioic acid 3-cyano-3,3-diphenylpropyl ester (M7), 4-hydroxymethylpiperazine-1-carbothioic acid S-(3-cyano-3,3-diphenylpropyl) ester (M8) and the sulfine of [4-methylpiperazine-1-carbodithioic acid 3-cyano-3-(4-hydroxyphenyl)-3-phenylpropyl ester] (M9).