• Journal of Electrochemical Science and Technology
• /
• v.13 no.3
• /
• pp.362-368
• /
• 2022

The application of polymer composite electrolyte in all-solid-state lithium-sulfur battery (ASSLSBs) can guarantee high energy density and improve the interface contact between electrolyte and electrode, which has a broader application prospect. However, the inherent insulation of the sulfur-cathode leads to a low electron/ion transfer rate. Carbon materials with high electronic conductivity and electrolyte materials with high ionic conductivity are usually selected to improve the electron/ion conduction of the composite cathode. In this work, PEO-LiTFSI-LLZO composite polymer electrolyte (CPE) with high ionic conductivity was prepared. The ionic conductivity was 1.16×10^-4 and 7.26×10^-4 S cm^-1 at 20 and 60℃, respectively. Meanwhile, the composite sulfur cathode was prepared with Sulfur, reduced graphene oxide and composite polymer electrolyte slurry (S-rGO-CPEs). In addition to improving the ion conductivity in the cathode, CPEs also replaces the role of binder. The influence of different contents of CPEs in the cathode material on the performance of the constructed battery was investigated. The results show that the electrochemical performance of the all-solid-state lithium-sulfur battery is the best when the content of the composite electrolyte in the cathode is 40%. Under the condition of 0.2C and 45℃, the charging and discharging capacity of the first cycle is 923 mAh g^-1, and the retention capacity is 653 mAh g^-1 after 50 cycles.

• Journal of Adhesion and Interface
• /
• v.13 no.3
• /
• pp.137-144
• /
• 2012

Chemical functionalization of carbon nanomaterials (CNMs) is generally carried out for increasing interfacial adhesion between filler and polymer matrix for CNM-polymer nanocomposites. The chemically functionalized CNTs can produce strong interfacial bonds with many polymers, allowing CNT based nanocomposites to possess high mechanical and functional properties. Hence, increased surface adhesion can be measured indirectly by observing increased mechanical properties. However, there is a more direct way to observe interfacial bonds between polymer and CNM by measuring piezoresistivity behavior so that we can imagine the behavior of CNM particles in polymer matrix under deflection. Fuctionalization of MWCNT and rGO was carried out by oxidization reaction of MWCNT and rGO with $H_2SO_4/HNO_3$ solution. Electrical resistivities of MWCNT-PMMA and rGO-PMMA composites were decreased after functionalization because of the destructive fuctionalization process. Meanwhile, piezoresistivities of functionalized CNM-PMMA composites showed more sensitive behavior under the same deflection as compared to pristine CNM-PMMA composites. Therefore, mobility of CNM in polymer matrix was found to be improved with chemical functionalization.

• Membrane Journal
• /
• v.32 no.6
• /
• pp.486-495
• /
• 2022

This study presents the improved recovery efficiency of rare metal ions through the modified separation membrane wettability and hydrogen ion permeation in the anion exchange membrane (AEM) under the recovery process of combined electrodialysis and solvent extraction. Specifically, the wettability of the separator was enhanced by hydrophilic modification on one separator surface through polydopamine (PDA) and lipophilic modification on the other surface through SiO₂ or graphene oxide (GO). In addition, the modified surface of AEM with polyethyleneimine (PEI), PDA, poly(vinylidene fluoride) (PVDF), etc. reduces the water uptake and modify the pore structure for proton ions generation. The suppressed transport resulted in the reduced hydrogen ion permeation. In the characterization, the surface morphology, chemical properties and composition of membrane or AEM were analyzed with Scanning Electron Microscopy (SEM) and Fourier Transform-Infrared Spectroscopy (FT-IR). Based on the analyses, improved extraction and stripping and hydrogen ion transport inhibition were demonstrated for the copper ion recovery system.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2016.11a
• /
• pp.122.2-122.2
• /
• 2016

Surface topographical cues has been highlighted to control the fate of neural stem cells (NSCs). Herein we developed a hierarchically patterned substrate (HPS) platform for regulating NSC differentiation. The HPS induced cytoskeleton alignment and highly activated focal adhesion in hNSCs as indicated by enhanced expression of focal adhesion proteins such as focal adhesion kinase (FAK) and vinculin. hNSCs cultured on HPS exhibited enhanced neuronal differentiation compared to flat group. We also developed a graphene oxide (GO)-based hierarchically patterned substrates (GPS) that promote focal adhesion formation and neuronal differentiation of hNSCs. Enhanced focal adhesion and differentiation of hNSCs on the HPS was reversed by blocking the ${\beta}1$ integrin binding and mechanotransduction-associated signals including Rho-associated protein kinase (ROCK) and extracellular-regulated kinase (ERK) pathway, which may suggest a potential mechanism of beneficial effects of HPS. In addition, hNSCs on the HPS differentiated into functional neurons exhibiting sodium currents and action potentials as confirmed by whole cell patch-clamping analysis. The hierarchical topography can direct differentiation of NSCs towards functional neurons, and therefore would be an important element for the design of functional biomaterials for neural tissue regeneration applications.

• Journal of Electrochemical Science and Technology
• /
• v.15 no.3
• /
• pp.321-344
• /
• 2024

Transition metal compounds (TMCs) are being researched as promising electrode materials for electrochemical energy storage devices (supercapacitors). Among TMCs, transition metal phosphates (TMPs) have good, layered structures owing to open framework and protonic exchange capability among different layers, good surface area due to engrossed porosity, rich active redox reaction sites owing to octahedral structure and variable valance metallic ions. Hence TMPs become more ideal for supercapacitor electrode materials compared to other TMCs. However, TMPs have got some issues like low conductivity, rate performance, stability, energy, and power densities. But these problems can be addressed by making their composites with carbonaceous materials, e.g., carbon nanotubes (CNTs), graphene oxide (GO), graphitic carbon (GC), etc. A few factors like high surface area, excellent electrical conductivity of carbon materials and variable valence metal ions in TMPs caused great enhancement in their electrochemical performance. This article tries to discuss and compare the published data, majorly in last decade, regarding the electrochemical energy storage potential of pristine unary, binary, and ternary TMPs and their hybrid composites with carbonaceous materials (CNTs, GOs/rGOs, GC, etc.). The electrochemical performance of the hybrids has been reported to be higher than the pristine counterparts. It is hoped that the current review will open a new gateway to study and explore the high performance TMPs based supercapacitor materials.

• Journal of Food Hygiene and Safety
• /
• v.32 no.2
• /
• pp.83-88
• /
• 2017

We introduced disposable amperometric immunosensors for the detection of Sildenafil and Vardenafil (SDF/VDF) based on screen printed carbon electrodes. The developed immunosensors were used as a non-competitive sandwich-type enzyme immunoassay with a horseradish peroxidase label. The sensors were constructed on screen printed carbon electrodes by the simple electrochemical deposition of a reduced graphene oxide and chitosan (ErGO-CS) composite. To evaluate the sensing chemistry and optimize the sensor characteristics, a series of electrochemical experiments were carried out including electrochemical impedance spectroscopy, cyclic voltammetry and amperometry. The sensors showed a linear response to SDF/VDF concentrations in a range from 100 pg/mL to 300 ng/mL. The lower detection limit was calculated to be 55 pg/mL, the sensitivity was calculated to be $1.02{\mu}Ang/mL/cm^2$, and the sensor performance exhibited good reproducibility with a relative standard deviation (RSD) of 7.1%. The proposed sensing chemistry strategy and the sensor format can be used as a simple, cost-effective, and feasible method for the in-field analysis of SDF/VDF in functional or health supplement food samples.