1,721,020 research outputs found
Die deflection effects on the metal flow pattern in plane-strain compressions with laboratory testing equipment.
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Electro-polymerized polyaniline modified conductive bacterial cellulose anode for supercapacitive microbial fuel cells and studying the role of anodic biofilm in the capacitive behavior
Full text linkPolyaniline modified conductive bacterial cellulose (BC-CNT-PANI) membrane is proposed as a novel bioanode for microbial fuel cell (MFC). BC is coated with CNT by vacuum filtering to form a conductive electrode (BC-CNT). Then the conductive side is coated with PANI through a fast and easy electro-polymerization (BC-CNT-PANI). Both anode electrodes are studied in supercapacitive MFCs (SCMFCs) by impedance analysis before and after biofilm formation on their surface. By bacteria colonization on the anodes’ surface, charge transfer resistance (Rct) of BC-CNT increases significantly from 14.5 Ω to 72 Ω while for BC-CNT-PANI, Rct decreases by 50%. Also, after biofilm formation, BC-CNT-PANI achieves a capacitance two times higher than that of BC-CNT. The SCMFCs are assembled and tested with BC-CNT, BC-CNT-PANI, and the double-anode BC-CNT& BC-CNT-PANI. Polarization, power density and galvanostatic discharge tests imply on an improvement in the SCMFC performance by using BC-CNT-PANI. The performance of the SCMFCs are limited by the anodes. The power density improves by 20% with the PANI-modified anode compared to the BC-CNT
Fabrication of a 2.8 v high-performance aqueous flexible fiber-shaped asymmetric micro-supercapacitor based on MnO2/PEDOT:PSS-reduced graphene oxide nanocomposite grown on carbon fiber electrode
Full text linkFlexible and lightweight fiber-shaped micro-supercapacitors have attracted tremendous attention as next-generation portable electronic devices, due to their high flexibility, tiny volume, and wearability. Herein, we successfully fabricated a ternary binder-free nanocomposite of MnO2/PEDOT:PSS-rGO on a carbon fiber substrate for application in high performance fiber-shaped micro-supercapacitors. The synergistic effects of the different components in the fiber-shaped electrode help to deliver a high specific capacitance of 2.9 F cm-2 (194 F cm-3 and 550 mF cm-1) at a current density of 5 mA cm-2 and a long cycle life with 95% capacitance retention after 5000 cycles in 1 M Na2SO4 electrolyte. A fiber-shaped asymmetric micro-device based on the resulting hybrid electrode was assembled. A maximum energy density of EA = 295 μW h cm-2 (EV = 19 mW h cm-3) and power density of PA = 14 mW cm-2 (PV = 930 mW cm-3) were achieved in an operating voltage window of 0-2.0 V in a solid-state Na2SO4-CMC electrolyte. Moreover, a fiber-shaped asymmetric micro-device with a super-concentrated potassium acetate-based water-in-salt electrolyte (27 m KOAC) is presented. The use of the water-in-salt electrolyte enables a cell voltage of 2.8 V, and energy densities are higher than those of the micro-device operating with conventional dilute aqueous electrolytes. This journal i
Increasing bioelectricity generation in microbial fuel cells by a high-performance cellulose-based membrane electrode assembly
Full text linkEconomically harvesting energy from a microbial fuel cell (MFC), increasing its electrical power production, and developing its role as a practical energy supply, needs a low-cost and high-performance design of the MFC compartments. According to this strategy, a novel monolithic membrane electrode assembly (MEA) was fabricated and evaluated as an air–cathode in a single-chamber MFC (SCMFC). The MEA was made of bacterial cellulose (BC), conductive multi-walled carbon nanotubes (CNT), and nano-zycosil (NZ). BC, as a nano-celluloses with oxygen barrier property, can maintain anaerobic conditions for the anode compartment. Binder-less CNT coating on BC avoids costly binders such as poly-tetra fluoro ethylene (PTFE) and Nafion and decreases the MEA charge transfer resistance. NZ, as a very cheap modifier, not only prevents the anolyte leakage but also provides more MEA's active sites for the oxygen reduction reaction (ORR). The electrochemical performance of the MEA was compared to a PTFE- based gas diffusion electrode (GDE) in the SCMFC. The MEA cell provided a pulse power density of 1790 mW/m2, roughly twice as high as the pulse power density of GDE (920 mW/m2). SCMFC's internal resistance decreased from 1.84 KΩ (with GDE) to 0.8 KΩ (with MEA). Also, the cell's columbic efficiency increased from 4.2% (with GDE) to11.7% (with MEA). Additionally, the capacitance of the MEA (65 mF) was much higher than the value for GDE (0.73 mF). Thus, the MEA compared to the GDE showed higher performance in the SCMFC for electricity generation and wastewater treatment at a lower cost
Supercapacitive operational mode in microbial fuel cell
Full text linkSupercapacitive microbial fuel cells (SC-MFCs) are an emerging and promising field that has captured the attention of scientists in the past few years. This hybridization consists in the integration of supercapacitive features in the MFC electrodes to boost the performance output. The MFC anaerobic and aerobic enviroments induce self-polarization of the electrodes. The electrodes can be discharged galvanostatically and then self-recharged by the biotic/abiotic environments. During the discharge, two main phenomena named electrostatic and faradaic take place but the separation and quantification of the two contributes seems to be challenging. Galvanostatic discharges of SC-MFC produce at least one order of magnitude higher current/power compared with continuous operations, making it promising for pulsed type applications.</p
Batteries
No full textThis chapter is not intended as an exhaustive treatment of batteries as such. Rather, it seeks to bring to the fore the wide-ranging importance of one application of electron transfer: batteries. Of no less importance in this connection is the enormous effort of interdisciplinary research needed to develop batteries responsive to scientific advances and technological innovations-research that is strengthened under
the pressure of market demand
3D Network of Sepia Melanin and N- and, S-Doped Graphitic Carbon Quantum Dots for Sustainable Electrochemical Capacitors
No full textOrganic electrode materials operating in aqueous electrolytes offer the opportunity to avoid toxic, critical, and expensive materials for electrochemical energy storage. When deposited on carbon current collectors, redox active organic materials add faradaic to electrostatic capacitance contribution to the electrodes. Here, a 3D network electrode material is reported upon, based on sepia melanin, a quinone macromolecule, and nitrogen- and sulfur-doped graphitic carbon quantum dots (N,S GCQDs) designed to achieve good electronic conductivity and electrolyte wettability. The effect of various undoped and doped carbon quantum dots is also investigated, synthesized from acetic acid and sucrose instead of graphite, on the electrochemical performance of sepia melanin. Sepia/N,S GCQD shows optimum areal capacitance (≈180 mF cm−2) that is about twice as high as sepia (≈77 mF cm−2) with lower charge transfer resistance (1 ohm for sepia/N,S GCQDs compared to 10 ohms for sepia). The sepia/N,S GCQD symmetric supercapacitor in 0.5 m Na2SO4(aq) exhibits promising capacitance retention ≈92% after 10 000 cycles at 5 A g−1, 100% coulombic efficiency, 11 μW h cm−2 and 102 mW cm−2 maximum energy and power densities. The work paves the way for stable and potentially biodegradable supercapacitor electrode materials for environmentally benign electrochemical energy storage
Semi-solid lithium/oxygen flow battery: an emerging, high-energy technology
Full text linkLithium-Air (O2) batteries are considered one of the nextgeneration battery technologies, due to their very high specific much attention for energy transition because of their highly flexible design that enables the decoupling of energy and power. However, commercial RFBs still suffer from low energy density. One of the solutions proposed to increase the energy density is the combination of the high energy density of the Li/ O2 battery with the flexible and scalable architecture of redox flow batteries in semi-solid flow Li/O2 batteries. The challenging activities to develop materials and components, and to prototype semi-solid flow Li/O2 batteries are here presented and discussed
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