Nonaqueous Electrolyte Systems

Nonaqueous Solvents and Solutes Used in Carbon-Based Electrochemical Capacitors 

These are essentially the same electrolyte solutions that have been found useful for nonaqueous lithium batteries, and their properties relevant to that application have been reviewed (54). Other advantages may include low leakage currents and absence of gas evolution on overcharge. The conductivities of these electrolytes, however, are much lower than those of aqueous solutions and ein increeise in series resistance is unavoidably associated with their use. Although detailed transient or impedance studies appear not to have been published, it is safe to assume that the Increase in electrolyte resistivity is also detrimental to dynamic response, because of increased transmission line effects in the porous electrode structures. 

Nawa et al. (56) have also described a capacitor based on the same type of C2irbon using LiCI04 and 7-butyrolactone as the electrolyte. These authors believe that cell capacity is due to a superimposition of a doublelayer charging process and an electrolyte intercalation process (galvanic 

Nogami et al. (58) have described a symmetrical activated carbon fiber cell using BU4NCIO4 as the electrolyte. 

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Table 1.3. Metal electrode potentials in nonaqueous ) electrolyte systems ).

The liquid range of a nonaqueous electrolyte system is defined at the upper limit by the temperature at which one of its components begins to vaporize (also called the bubble temperature, Ob) and at the lower limit by the temperature at which one of its components begins to crystallize (liquidus temperature, Apparently, along with restrictions im-... 

Another approach is to use a lithium/sulfur cell with nonaqueous electrolyte systems. Rechargeable lithium batteries are being developed for portable power applications such as electric vehicles, partly because of their specific energy ranges 100-150 Wh kg (and... 

High energy density batteries are a crucial need as modern electronics progresses and moves more and more toward miniaturization. Many novel battery systems require the use of nonaqueous electrolyte systems because important new developments in this field are based on active metal electrodes (eg, Li and Li-C intercalation compounds). 

Consequently, there is an increasing interest in alternative (or additional) electrolyte systems in which the above limitations can be removed. Providing the answers to the above limitations of aqueous solutions and the study, matching, and classification of alternative/additional electrolyte systems is the essence of nonaqueous chemistry. An overview of this branch of modern electrochemistry should include the presentation and classification of the important nonaqueous electrolyte systems, indicating their basic features, advantages, and limitations, as well as a short review of their typical applications. 

The important nonaqueous electrolyte systems may be divided into five groups ... 

The nonaqueous electrolyte systems mentioned in this section are solid state systems which may be very important and promising for some types of batteries and fuel cells applications. 

In the case of ion conductive polymers, gel polymer electrolytes which consist of a polymer matrix, organic solvents and supporting electrolyte, were introduced as novel nonaqueous electrolyte systems in electrochemical applications, such as rechargeable batteries and electric double layer capacitors [3-5], Recently, considerable attention has been devoted to the application of gel poly-... 

The substantially lower freezing point of many nonaqueous electrolyte systems relative to aqueous systems enables reasonably good low temperature performance, sometimes down to -40°C. 

Thus, the chemistry of HF in nonaqueous electrolyte solution is very important even though its content is in the order of 100 ppm. Therefore, much attention has to be paid on the synthesis and stability of fluoride compounds in nonaqueous electrochemistry and battery field. In particular, new compounds containing fluorine would be more and more important to realize more reliable nonaqueous electrolyte system and interface control in rechargeable lithium batteries. 

Organic solvents show a different solvating power relative to each other and to water. Table 8.3. The driving force for exploring nonaqueous electrolyte systems is that the right choice of solvent may yield separations that are impossible in... 

NONAQUEOUS ELECTROLYTE SYSTEMS IONIC TRANSPORT IN NONAQUEOUS MEDIA. INTERM TECHNICAL REPT NO. 7. 

E g ) after 100,000 cycling, while the capacity decreased down to 5 Ah kg for a polyindole electrode. In the case of above nonaqueous electrolyte system, CIT maintained 70 % (55 Ah kg ) of its initial capacity after 50,000 cycles (Scheme 1). 

To achieve higher energy density and higher voltage operation than aqueous ECs utilizing the bromide system, nonaqueous electrolyte systems have also been proposed such as an ionic liquid electrolyte-based EC system [47] and lithium-ion capacitor system [48]. 

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