Designing the optimum cathode configuration for lithium−sulfur (Li−S) batteries has held tremendous scientific momentum to achieve high energy density, fast reaction kinetics, and superior cycle retention. Herein, a self-standing and flexible PPy@rGO/CNTs (PCG) paper as sulfur host is constructed by integrating multiwalled carbon nanotubes into polypyrrole@reduced graphene oxide hybrid structure, rooted from in situ redox reaction and spontaneous assembly of pyrrole and graphene oxide. The three-dimensional (3D) corrugated papery frameworks with carbon nanotube (CNT) pillars deliver a highly conducting pathway for electron and ion transfer. Theoretical calculations indicate that ample nitrogen-and oxygen-containing functional groups can form strong polar−polar interaction with lithium polysulfides. Thus, the assembled lightweight PCG-S electrode exhibits a high gravimetric capacity of 1201.9 mA h g −1 and retains 727.8 mA h g −1 at 0.2 C after 450 cycles, remarkable rate performance, and excellent cyclic stability with an ultralow decay rate of 0.044% per cycle during 200 cycles at 1 C. Delightedly, thanks to its unique structure, the volumetric sulfur loading amount in the flexible electrode can reach ca. 0.82 g cm −3 , which endows the cathode with an ultrahigh volumetric capacity of 975 A h L −1 at 0.2 C simultaneously. This dense monolithic paper appears to be a scalable potential for developing high-performance cathodes in emerging flexible devices.
An experiment to recover lithium from high Mg(2+)/Li(+) ratio brine by nanofiltration (NF) was carried out. The combination of Donnan exclusion, dielectric exclusion and steric hindrance governed the mass transport inside the NF membrane. Experimental results showed that NF is an efficient technique to recycle Li(+) and reduce Mg(2+)/Li(+) ratio from high Mg(2+)/Li(+) ratio brine. When content reached 6.0 g/L, operating pressure reached 0.8 MPa and Mg(2+)/Li(+) ratio in feed was 40, the rejection of magnesium (R(Mg(2+))) and the separation factor (SF) were 0.96 and 42, respectively. The Mg(2+)/Li(+) ratio in permeate could be reduced to 0.9, and Li(+) recovery ratio was 85%. Adding potassium (K(+)) or sodium (Na(+)) to solution can reduce R(Mg(2+)) and SF.
Ionic liquid has relatively high conductivity at room temperature and good electrochemical stability. Ionic liquid polymer electrolytes have some advantages of both ionic liquid and polymer. In this work, 1-alkyl-3-(2′,3′-dihydroxypropyl)imidazolium chloride (IL-Cl) was incorporated into waterborne polyurethane chain to composite all-solid-state polymer electrolyte matrices. The structure, thermal stability, mechanical property and ionic conductivity of the matrices were investigated by Fourier transform infrared spectroscopy (FTIR), thermogravimetric Analysis (TGA), tensile measurement and electrochemical impedance spectroscopy (EIS). The results demonstrated that when the content of IL-Cl was 14 wt%, the mechanical property of film was optimized, with a maximum tensile strength of 36 MPa and elongation at break of 1030%. In addition, as for the film with IL-Cl content of 16 wt%, its oxygen index value increased to 25.2% and ionic conductivity reached a maximum of 1.2 × 10−5 S·cm−1 at room temperature, showing high flame retardancy and ionic conductivity.
Stimuli-responsive nanocarriers with the ability to respond to tumorous heterogeneity have been extensively developed for drug delivery. However, the premature release during blood circulation and insufficient intracellular drug release are still a significant issue. Herein, three disulfide bonds are introduced into the amphiphilic poly(ethylene glycol)-polycaprolactone copolymer blocks to form triple-sensitive cleavable polymeric nanocarrier (tri-PESC NPs) to improve its sensitivity to narrow glutathione (GSH) concentration. The tri-PESC NPs keep intact during blood circulation due to the limited cleaving of triple-disulfide bonds, whereas the loaded drug is efficiently released at tumor cells with the increased concentration of GSH. In vitro studies of doxorubicin-loaded tri-PESC NPs show that the nanocarriers achieve sufficient drug release in cancerous cells and inhibit the tumor cells growth, though they only bring minimum damage to normal cells. Therefore, the tri-PESC NPs with triple-sensitive cleavable bonds hold great promise to improve the therapeutic index in cancer therapy.
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