1,721,015 research outputs found
The role of carbon paper as current collector-substrate in tin-based anodes for lithium-ion batteries
No full textThe strategies of the intermetallic compounds and of morphological conversion toward nanomaterials to buffer the volume changes during the lithiation/delithiation processes in lithium-metal alloys, although beneficial, have been not conclusive to overcome this drawback.
To improve the cyclability performance of nanometric lithium-metal alloys we regarded the electrode materials as a whole with the current collector and we focused our efforts on the carbon paper (CP) as an alternative substrate-current collector to the conventional copper. The CP, with its three-dimensional interconnected conductive fibers, was able to host the metals and intermetallic materials and to guarantee a good electric contact without addition of carbon as conducting agent, providing a significantly improved cycling stability of these electrodes as shown in Figure 1.
To get an insight into the effective role of CP on the cycling stability of lithium-metal alloy/CP electrodes we compared the electrochemical and structural behavior over repeated lithiation/delithiation cycles of different types of tin-based materials on CP such as Sn, Cu6Sn5 and Sn2Mn and the results of this study are presented and discussed in this contribution
Fast sol-gel synthesis of LiFePO4/C for high power lithium-ion batteries for hybrid electric vehicle application
No full textLiFePO4/C of high purity grade was successfully synthesized by microwave accelerated sol-gel
synthesis and showed excellent electrochemical performance in terms of specific capacity and
stability. This cathode material was characterized in battery configuration with a graphite counter
electrode by USABC-DOE tests for Power-Assist Hybrid Electric Vehicle. It yielded a nonconventional
Ragone plot that represents complexity of battery functioning in power-assist HEV
and shows that the pulse power capability and available energy of such a battery surpasses the DOE
goal for such an application
Cyclability of tin and tin-based intermetallic compounds on carbon paper current collector-substrate
No full textAlthough lithium-ion battery technology is well consolidated, research efforts have been greatly active in attempts to ameliorate the performance of these batteries. In particular, the research on negative electrodes has been not only focused on the optimization of carbonaceous materials but also on alternative materials, such as lithium-metal alloys, which are very attractive for their specific capacity. However, their high volume changes during the lithiation/delithiation processes cause materials pulverization and, consequently, loss of electrical contact among particles, determining poor cycle life. The strategies of the intermetallic compounds and of morphological conversion toward nanomaterials to buffer the volume changes, although beneficial, have been not conclusive to overcome this drawback.
To improve the cyclability performance of nanometric lithium-metal alloys we regarded the electrode materials as a whole with the current collector and we focused our efforts on the carbon paper (CP) as an alternative substrate-current collector to the conventional copper. The CP, with its three-dimensional interconnected conductive fibers, was able to host the metals and intermetallic materials and to guarantee a good electric contact without addition of carbon as conducting agent, providing a significantly improved cycling stability of these electrodes.
To get an insight into the effective role of CP on the cycling stability of lithium-metal alloy/CP electrodes we compared the electrochemical and structural behavior over repeated lithiation/delithiation cycles of different types of tin-based materials on CP such as Sn, Cu6Sn5 and Sn2Mn and the results of this study are presented and discussed in this contribution
Il ruolo del carbon paper come substrato-collettore di corrente in anodi a base di stagno per batterie litio-ione
No full textLe strategie dei composti intermetallici e della conversione morfologica verso i nanomateriali per contrastare le variazioni di volume durante i processi di litiazione/delitiazione delle leghe litio-metallo, sebbene abbiano apportato notevoli benefici, non hanno ancora risolto questo problema che costituisce una forte limitazione all’impiego di tali materiali nelle batterie litio-ione.
Per migliorare le prestazioni in termini di vita di ciclo delle leghe nanometriche litio-metallo abbiamo considerato il materiale elettrodico come un tutto con il suo collettore di corrente ed abbiamo focalizzato la nostra attenzione sul carbon paper (CP) proponendolo come substrato-collettore alternativo al rame comunemente usato. Il CP, con la sua matrice tridimensionale di fibre conduttrici interconnesse, si è dimostrato in grado di ospitare Sn e composti intermetallici a base di Sn e di garantire un buon contatto elettrico senza l’aggiunta di carbone come additivo conduttore, fornendo una stabilità a ripetuti cicli di carica/scarica significativamente più elevata di quella ottenuta con i collettori di rame.
Per chiarire l’effettivo ruolo del CP sulla stabilità a ripetuti cicli di litiazione/delitiazione di elettrodi a base di Sn su tali collettori abbiamo confrontato il comportamento elettrochimico e strutturale durante ripetuti cicli di diversi tipi di elettrodo quali Sn/CP, Cu6Sn5/CP e Sn2Mn/CP e i risultati di questo studio sono presentati e discussi nel presente contributo
MW assisted synthesis of LiFePO4 for high power applications
No full textLiFePO4/C was prepared by solid-state reaction from Li3PO4, Fe3(PO4)2.8H2O, carbon and glucose in a few minutes in a scientific MW oven with temperature and power control. The material was characterized by X-ray diffraction, scanning electron microscopy and by TGA analysis to evaluate carbon content. The electrochemical characterization as positive electrode in EC- DMC 1 M LiPF6 was performed by galvanostatic charge–discharge cycles at C/10 to evaluate specific capacity and by sequences of 10 s discharge-charge pulses, at different high C-rates (5-45 C) to evaluate pulse-specific power in simulate operative conditions for full-HEV application. The maximum pulse-specific power and, particularly, pulse efficiency values are quite high and make MW synthesis a very promising route for mass production of LiFePO4/C for full-HEV batteries at low energy costs
A three-dimensional carbon-coated LiFePO4 electrode for high-power applications
No full textThe fabrication process of a new, threedimensional
carbon-coated LiFePO4 electrode by sol–gel
synthesis in situ on interconnected conducting fibers of
carbon paper is described. This three-dimensional structure
ensures overall electrode conductivity, facilitates lithium
diffusion in and out of LiFePO4 particles and, hence,
enables good cycling stability at 1C-rate and maximum
pulse-power values that exceed those of planar LiFePO4
electrodes at high electrode loading
Electrode materials for ionic liquid-based supercapacitors
No full textThe use of ionic liquid (IL) electrolytes is a promising strategy to enhance the performance of supercapacitors above room temperature. In this paper we present the results of a study on optimization of electrode materials for IL-based supercapacitors featuring a hybrid configuration with carbon negative electrode and poly(3-methylthiophene) (pMeT) as positive operating at 60°C with the ILs N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) and 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI). As it concerns the carbon electrode two routes have been pursued: i) surface modification of commercial activated carbon and ii) synthesis of mesoporous cryo- and xerogel carbons. Pore size distribution and electrochemical characterization data are related and suggest that the second route should be the most promising for carbons of high specific capacitance and low time constant in IL. For the polymer electrode the nature of the galvanostatic polymerization bath plays a crucial role to provide pMeT of high specific capacitance and the best results may be obtained when pMeT is electropolymerized in the same IL used for the capacitance tests. The strategy of using the acid additive trifluoromethanesulfonimide in IL-based polymerization baths is also described in some detail. This strategy that provides pMeT featuring more than 200 F g-1 in IL is a clean procedure which prevents consumption of the ionic liquid with great advantage in terms of costs
Cryo- and xerogel carbon supported PtRu for DMFC anodes
No full textThe specific catalytic activity of DMFC anodes based on PtRu may be improved using conducting carbon supports of high surface area and mesoporosity with pore size > 20 nm for a high accessible surface area. To this purpose we pursued the strategy of developing PtRu catalysts deposited by chemical and electrochemical route on mesoporous cryo- and xerogel carbons. Here we report the preparation and characterization data of different mesoporous cryo- and xerogel carbons as well as we present and discuss the results of the structural and morphological study and the catalytic activity data of PtRu catalysts chemically and electrochemically prepared, also by pulse techniques, on such carbons. The results are also compared to those obtained with PtRu supported on the generally used Vulcan carbon support
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