Battery technology electrolytes

Battery technology Electrolyte Mobile species in electrolyte Anode reaction during discharge Cathode reaction during discharge Standard cell potential / V Gravimetric energy density/ Wh kg-1 Notes... 

The galvanic cell studied (shown in Fig. 5.24) utilizes a highly porous solid electrolyte that is a eutectic composition of LiCl and KCl. This eutectic has a melt temperature of 352 °C and has been carefully studied in prior electrochemical studies. Such solid electrolytes are typical of thermal battery technology in which galvanic cells are inert until the electrolyte is melted. In the present case, shock compression activates the electrolyte by enhanced solid state reactivity and melting. The temperature resulting from the shock compression is controlled by experiments at various electrolyte densities, which were varied from 65% to 12.5% of solid density. The lower densities were achieved by use of microballoons which add little mass to the system but greatly decrease the density. 

Battery technology has developed enormously in recent years. One of the most useful types of batteries is known as the lithium battery, but there are actually several designs only one of which will be described. In one of the types, the anode is constructed of lithium or a lithium alloy hence the name. A graphite cathode is used, and the electrolyte is a solution of Li[AlCl4] in thionyl chloride. At the anode, lithium is oxidized,... 

The solid polymer electrolyte approach provides enhanced safety, but the poor ambient temperature conductivity excludes their use for battery applications. which require good ambient temperature performance. In contrast, the liquid lithium-ion technology provides better performance over a wider temperature range, but electrolyte leakage remains a constant risk. Midway between the solid polymer electrolyte and the liquid electrolyte is the hybrid polymer electrolyte concept leading to the so-called gel polymer lithium-ion batteries. Gel electrolyte is a two-component system, viz., a polymer matrix... 

Some of the most useful polyphosphazenes are fluoroalkoxy derivatives and amorphous copolymers (11.27) that are practicable as flame-retardant, hydrocarbon solvent- and oil-resistant elastomers, which have found aerospace and automotive applications. Polymers such as the amorphous comb polymer poly[bis(methoxyethoxyethoxy)phosphazene] (11.28) weakly coordinate Li " ions and are of substantial interest as components of polymeric electrolytes in battery technology. Polyphosphazenes are also of interest as biomedical materials and bioinert, bioactive, membrane-forming and bioerodable materials and hydrogels have been prepared. 

The problem of triple ion formation has been studied in detail, because it is related to lithium battery technologies [18]. In some cases, however, the occurrence of the minimum in the log A-log c curve, as observed in Fig. 7.2, is not attributed to triple-ion formation but is explained by ion-pair formation only. The increase in log A at high electrolyte concentrations is attributed either to the increase in the distance of closest approach of ions, the increase in the solution permittivity, or the decrease in the activity coefficient of the ion-pairs. Although there is still some controversy, it seems certain that triple ions are actually formed in many cases. 

Numerous other battery chemistries have evolved over time. The most prominent ones are assembled in Table 3.5.2. One possible categorization of battery technologies can be made according to the class of electrolyte they use. Here, we will distinguish between liquid aqueous, liquid nonaqueous, and solid electrolytes. To a certain degree, the phase state of the electrolyte determines the state of the electrodes. In general, it is advantageous to have a solid/liquid phase boundary between electrode and electrolyte because of much lower contact resistance in comparison to solid/solid contacts. Therefore, if the electrodes are solids, the electrolyte should be preferably liquid and vice versa. 

Nowadays, the most prominent battery technology is based on lithium storage and employs a nonaqueous liquid electrolyte. Before we focus on these systems, we will address selected rechargeable systems based on other elements. 

LiVMoOe was successfully synthesized using the conventional solid-state reaction method, and its chemical and physical properties were examined by several analytical methods. We have shown that LiVMoOe does not possess good structural characteristics for a lithium half cell (Li/LiVMoOe) as a cathode in non-aqueous electrolyte environment. Furthermore, we suggest that LiVMoOe may instead be considered as an anode material of choice for developing rechargeable lithium-ion battery technology. 

Li-based battery technologies continue to be developed. The materials research aspect is particularly intense new and better electrolyte and electrode materials are designed and investigated (see Li-ion conductors in Section 3) to minimize deleterious reactions occurring at the electrode-electrolyte interface the critical phase of all electrochemical systems. 

Another approach to consistent power delivery from renewable sources is to consider the use of supercapacitors placed between the renewable power source and the electrolyzer. These may or may not be viable, and we have not yet researched this possibility. Supercapacitors are basically a cross between capacitor and battery technology. They use electrodes, and a liquid or organic electrolyte, but they store energy by static charge rather than by electrochemical means. They can be cycled millions of times, and have a recharge time of seconds. Supercapacitors might also be viable to enhance peak load performance on the fuel cell end. 

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