Electrochemical performance of electrode

Wu, Y.P., Rahm, E., and Holze, R. (2002). Effects of heteroatoms on electrochemical performance of electrode materials for hthium ion batteries. Electrochim. Acta, 47, 3491-507. 

As shown in Figure 13.4, it can be seen clearly that addition of a conductive agent greatly improves the electrochemical performance of electrode... 

The disproportionation reaction destroys the layered structure and the two-dimensional pathways for lithium-ion transport. For >0.3, delithiated Li, AV02 has a defect rock salt structure without any well-defined pathways for lithium-ion diffusion. It is, therefore, not surprising that the kinetics of lithium-ion transport and overall electrochemical performance of Li, tV02 electrodes are significantly reduced by the transformation from a layered to a defect rock salt structure [76], This transformation is clearly evident from the... 

The recovery of petroleum from sandstone and the release of kerogen from oil shale and tar sands both depend strongly on the microstmcture and surface properties of these porous media. The interfacial properties of complex liquid agents—mixtures of polymers and surfactants—are critical to viscosity control in tertiary oil recovery and to the comminution of minerals and coal. The corrosion and wear of mechanical parts are influenced by the composition and stmcture of metal surfaces, as well as by the interaction of lubricants with these surfaces. Microstmcture and surface properties are vitally important to both the performance of electrodes in electrochemical processes and the effectiveness of catalysts. Advances in synthetic chemistry are opening the door to the design of zeolites and layered compounds with tightly specified properties to provide the desired catalytic activity and separation selectivity. 

Porous electrodes are commonly used in fuel cells to achieve hi surface area which significantly increases the number of reaction sites. A critical part of most fuel cells is often referred to as the triple phase boundary (TPB). Thrae mostly microscopic regions, in which the actual electrochemical reactions take place, are found where reactant gas, electrolyte and electrode meet each other. For a site or area to be active, it must be exposed to the rractant, be in electrical contact with the electrode, be in ionic contact with the electrolyte, and contain sufficient electro-catalyst for the reaction to proceed at a desired rate. The density of these regions and the microstmcture of these interfaces play a critical role in the electrochemical performance of the fuel cells [1]. 

The pores of the silica template can be filled by carbon from a gas or a liquid phase. One may consider an insertion of pyrolytic carbon from the thermal decomposition of propylene or by an aqueous solution of sucrose, which after elimination of water requires a carbonization step at 900°C. The carbon infiltration is followed by the dissolution of silica by HF. The main attribute of template carbons is their well sized pores defined by the wall thickness of the silica matrix. Application of such highly ordered materials allows an exact screening of pores adapted for efficient charging of the electrical double layer. The electrochemical performance of capacitor electrodes prepared from the various template carbons have been determined and are tentatively correlated with their structural and microtextural characteristics. 

Electrochemical performance of the modified carbons was examined by floating gas diffusion electrode [19] in an electrochemical cell with separated cathode and anode chambers at room temperature with PI-50-1.1 -potentiostat in IN KOH aqueous solution. 

The seven papers in Chapter 6 are focused on cathode materials for lithium and lithium-ion batteries. Carbon is used as a conductive additive in composite electrodes for batteries. The type of carbon and the amount can have a large effect on the electrochemical performance of the electrode. 

P.C. Pandey, S. Upadhyay, N.K. Shukla, and S. Sharma, Studies on the electrochemical performance of glucose biosensor based on ferrocene encapsulated ORMOSIL and glucose oxidase modified graphite paste electrode. Biosens. Bioelectron. 18,1257—1268 (2003). 

Chung BW, Pham A-Q, Haslam JJ, and Glass RS. Influence of electrode configuration on the performance of electrode-supported solid oxide fuel cells. J Electrochem Soc 2002 149 A325-A330. 

The electrochemical performance of La,.6Sr0 4Coo.2Feo.803 (LSCF6428) composition was characterized by Esquirol et al. [102], At 600°C, the conductivity of a porous LSCF coating with thickness of 10 pm was 52.8 and 29.2 Scm 1 when sintered at 1000 and 850°C, respectively. This conductivity is considerably lower than the conductivity values for dense LSCF (300 to 400 Scm-1)- The electrode polarization resistance of LSCF sintered at 850°C was 7.5, 0.23, and 0.03 ohm cm2 at 502, 650, and 801°C, respectively, lower than the electrode polarization resistance values at the same temperatures for the LSCF cathode sintered at 1000°C. The results show that the electrochemical activity of the LSCF electrode for the 02 reduction at... 

Fig. 7.11 Electrochemical performance of different carbons using a three-electrode cell in 1 mol L 1 H2S04 (a) cyclic voltammograms at a scan rate of 1 mV s 1, (b) galvanostatic charge/discharge curves at a current density of 0.2 Ag 1, (c) relationship of the specific capacitance with respect to the charge/discharge specific currents, and (d) Ragone plots.

In-situ electrochemical techniques may be conveniently used to analyse the fundamental thermodynamic and kinetic parameters which are responsible for the performance of electrodes. The methods are nondestructive and may be applied to the actual galvanic cell. The data may be easily determined as a function of the discharge state. 

Layered nickel hydroxide can be used as an electrode for alkaline secondary cells. To improve its properties, modification has been carried out by incorporation of other metal elements to form Ni/M LDHs, including Co [221], Zn [222], Al [223], Cr or Mn [224] and Fe [225]. For example, Chen et al. reported the electrochemical performance of Al-substituted layered a-... 

In general, the electrochemical performance of carbon materials is basically determined by the electronic properties, and given its interfacial character, by the surface structure and surface chemistry (i.e. surface terminal functional groups or adsorption processes) [1,2]. Such features will affect the electrode kinetics, potential limits, background currents and the interaction with molecules in solution [2]. From the point of view of electroanalysis, the remarkable benefits of CNT-modified electrodes have been widely praised, including low detection limits, increased sensitivity, decreased overpotentials and resistance to surface fouling [5, 9, 11, 17]. 

To summarize, one can say that the electrochemical performance of CNT electrodes is correlated to the DOS of the CNT electrode with energies close to the redox formal potential of the solution species. The electron transfer and adsorption reactivity of CNT electrodes is remarkably dependent on the density of edge sites/defects that are the more reactive sites for that process, increasing considerably the electron-transfer rate. Additionally, surface oxygen functionalities can exert a big influence on the electrode kinetics. However, not all redox systems respond in the same way to the surface characteristics or can have electrocatalytical activity. This is very dependent on their own redox mechanism. Moreover, the high surface area and the nanometer size are the key factors in the electrochemical performance of the carbon nanotubes. 

Carbon nanotubes inevitably contain defects, whose extent depends on the fabrication method but also on the CNT post-treatments. As already seen, oxidizing treatments, such as acid, plasma or electrochemical, can introduce defects that play an important role in the electrochemical performance of CNT electrodes. For instance, Collins and coworkers have published an interesting way to introduce very controlled functionalization points or defects on individual SWNTs by electrochemical means [96]. Other methodologies to introduce artificial defects comprise argon, hydrogen and electron irradiation. Under this context, a number of recent works have appeared with the goal of tailoring the electrochemical behavior of CNT surfaces by the controlled introduction of defects [97, 98]. 

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