Ionic conductivity values

Bulk ionic conductivities of the samples were measured by impedance analysis between room temperature and 545°C. The extrapolated ionic conductivity could be as high as 0.14-0.16 S/cm at 800°C. This value is very promising, however, caution should be exercised in interpreting this extrapolated ionic conductivity value. A change in the slope of log(cjT) versus 1/T plot is suspected in the literature above 550°C. 

Sizes of Bare and Hydrated Ions, and Ionic Conductivity Values... 

Alkaline PEO-based SPE may be limited by the high crystallinity and poor thermal stability. Vassal et al. [11] intended to use amorphous copolymer, poly(epichlorohydrin-co-ethylene oxide) P(ECH-co-EO), and presented good electrochemical properties without PEO s disadvantages. The ionic conductivity value at room temperature was around 10 S cm". The all solid-state alkaline Ni/MH and Zn/air electrochemical cells also exhibited stable behavior. 

The salt most commonly used in Li-S batteries is LiTFSI, which exhibits good chemical, thermal and electrochemical stability (no corrosion of the aluminum in the window of potential of the sulfur electrode, no formation of hydrofluoric acid - HF). Similarly, because of its high degree of dissociation in ethers, it enables us to obtain good ionic conductivity values, of around 5xlO S/cm at 20°C. Hence, it constitutes an alternative to LiPFe salt which is used in conventional lithium-ion batteries but is not very soluble in ether solvents. 

Selected ionic conductivity values for solvent-electrolyte combinations... 

Ionic conductivity values for some exotic electrolytes... 

A list of representative limiting ionic conductivity values and related parameters is given in the next section. 

The conductivity observed during cooling down from 200°C is also Arrhenius-type however, it is three orders of magnitude lower than the conductivity of the samples before drying. In passing, one notes that in contrast to the huge discrepancy of the ionic conductivity values of humid and dried NaPSS/PDADMAC PEC, the activation enthalpy of the conductivity is almost identical. The latter finding is... 

Generally, in a fuel cell, the electrolyte ohmic overpotential is the dominant component of the ohmic overpotential owing to the lower ionic conductivity value as compared to the electronic conductivity of electrodes and interconnect materials. Research effort to improve ohmic loss in a fuel cell is, therefore, focused on the improvement of the electrolyte in terms of higher ionic conductivity and lower thickness. Use of a thinner electrol5de is limited by a number of factors such as structural integrity, manufacturability and defects, increased parasitic loss owing to fuel crossover loss, and dielectric limit of the electrolyte. 

Asa result of the competing trends in conductivity, theoretical values often differ from those experimentally measured. Some typical electrolyte ionic conductivity values are given in Table 5.3. It should be noted that the values in Table 5.3 are under ideal conditions, and actual values in fuel cells may not exactly match. 

Abstract The development of new materials that can be apphed as solid electrolytes has led to the creation of modern systems of energy generation and storage. Among different poly(ethylene oxide)-based electrolytes, natural polymers, snch as hydroxyethylcellnlose, hydroxypropylcellulose or carboxymethylcellulose, starch and chitosan or proteins like gelatin, are also proposed. After salt or acid addition, the transparent membranes show ionic conductivity values of 10 S/cm and can be apphed with good stability results to electrochromic devices. 

Natural polymer-based plastics can be also obtained through plasticiza-tioni5.i6.2o,2i Qj. g]-afting22 processes. The polymer electrolytes obtained by the plasticization process with low molecular weight substances increase the values of the ionic conductivity of the formed blends. TVlthough the mechanism is not yet well known, there is an interaction of ions with mobile specific sites along the polymer chain. Also the fact that a plasticizer separates the polymer chain enhances the assumptions about their important role in the increase of the ionic conductivity values. ... 

HPC-based SPEs were obtained by the introduction of LiC104 to these networks. The ionic conductivity values as a function of temperature showed two types of conductivity models, depending on the LiC104 concentration. For low ([0]/[Li] = 50) and high ([0]/[Li] = 6) salt quantities, an Arrhenius-... 

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