Battery performance graphitic carbons

In modem commercial lithium-ion batteries, a variety of graphite powder and fibers, as well as carbon black, can be found as conductive additive in the positive electrode. Due to the variety of different battery formulations and chemistries which are applied, so far no standardization of materials has occurred. Every individual active electrode material and electrode formulation imposes special requirements on the conductive additive for an optimum battery performance. In addition, varying battery manufacturing processes implement differences in the electrode formulations. In this context, it is noteworthy that electrodes of lithium-ion batteries with a gelled or polymer electrolyte require the use of carbon black to attach the electrolyte to the active electrode materials.49-54 In the following, the characteristic material and battery-related properties of graphite, carbon black, and other specific carbon conductive additives are described. 

Most battery systems employ carbon materials in one form or another, as noted in Table 10.1. The use of carbon materials in batteries stretches across a wide spectrum of battery technologies. The variety of carbon runs the gamut from bituminous materials, used to seal carbon-zinc and carbon black powders in lead acid batteries, to high performance synthetic graphites, used as active materials in lithium-ion cells. The largest use is as a conductive diluent to enhance the performance of cathode materials. In many instances, it is used as a conductive diluent for poorly conducting cathode materials where carbon blacks, such as acetylene black, are preferred. It is essential that... 

An interesting example of the application of perovskites as electrodes was published by Muller et al. (1994). Lao.6Cao4Co03 has excellent catalytic properties for O2 reduction and evolution as shown by Shimizu et al. (1990). In order to obtain a more durable electrode material, Muller et al. (1994) used graphitized carbon (70 m2/g) as support of the perovskite catalysts. They described in detail the technique used to prepare the electrode which was assayed using an experimental setup adequate for the intended application of this electrode, namely Zn/air batteries. Their main advance over previous formulations was to achieve longer durability of the electrode with some reduction in current density when compared to the previous work of Shimizu et al. (1990). The authors also suggest routes to improve the overall performance of this attractive system. 

The battery performance using natural graphite as an anode is often poor due to the reaction with the electrolyte to produce a highly resistive SET Special selected compounds such as vinyl acetate (VA), divinyl adipate (ADV), and allyl methyl carbonate (AMC) dissolved in an ordinary electrolyte are presented here to find the effectiveness of the additives. " Figure 19.11 shows the discharge capacity with cycles of positive active materials with and without the special functional additives compared to well-known ethylene sulfite (ES) additive. 

A composite electrode composed of graphite and carbon nanotube was fabricated by Zhu et al. [65]. The redox reactimis are reversible on graphite but not on carbon nanotube, but carbon nanotube was able to improve on the low ciurents of graphite. Recently, Li et al. [66] reported multiwaUed carbon nanotubes (MWCNTs) and functional MWCNTs as electrodes in RFBs. Different MWCNTs were used to modify glassy carbon electrodes, resulting in improved electrochemical activity of the redox couple and battery performance. The increased activities of modified electrodes were attributed to an increased electrode surface area and the introduction of oxygen functional groups. 

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