Liquid electrolyte cells

Other important parts of the cell are 1) the structure for distributing the reactant gases across the electrode surface and which serves as mechanical support, shown as ribs in Figure 1-4, 2) electrolyte reservoirs for liquid electrolyte cells to replenish electrolyte lost over life, and 3) current collectors (not shown) that provide a path for the current between the electrodes and the separator of flat plate cells. Other arrangements of gas flow and current flow are used in fuel cell stack designs, and are mentioned in Sections 3 through 8 for the various type cells. 

Studies by Sedlak (j6) have shown a similar response-flow relationship for liquid electrolyte cells which utilize a teflon-bonded diffusion electrode. The empirical equations and relationships derived generally apply to the SPE sensor cells. 

The use of quasi-solid-state electrolytes usually reaches the goal of a superior thermal stability with respect to liquid electrolytes cells can survive prolonged periods (accelerated aging of 1000 h) at relatively high temperatures (55-80°C) under... 

The lithium passivation in liquid electrolyte cells has been extensively investigated and its characteristics - in terms of nature and of growth rate of the passivation film, as well as its effect on the cyclability of the lithium electrode - have been well established. As a result of these studies, it is now clear that the efficiency of the lithium plating-stripping process greatly depends on the nature of the selected electrolyte solution. 

The ionic conductivity of most solid polymer electrolytes is significantly lower than that of the liquid electrolytes. Cells must he designed with thin electrodes and cell components to minimize the internal cell resistance. The total thickness of a cell assembly is as low as 200 fim or thinner. An alternative is to operate at higher temperatures where the conductivity is higher. While this may he acceptahle for electric-vehicle and stand-by batteries, it will not be acceptable for many portable consumer applications. Newer polymer electrolytes are being developed using plasticizers or gel-type polymers. These methods increase the conductivity of the polymers, but since they contain organic solvents, they will be more reactive with the lithium anode. 

Li-ion cells use thin (10 to 30 /u,m), microporous films to electrically isolate the positive and negative electrodes. To date, all commercially available liquid electrolyte cells use micro-porous polyolefin materials as they provide excellent mechanical properties, chemical stability and acceptable cost. Nonwoven materials have also been developed but have not been widely accepted, in part due to the difficulty in fabricating thin materials with uniform, high strength. ... 

In all cases, safety and abuse tolerance is stiU largely determined by the active materials that are used. The polymer electrolytes that do not contain solvents and plasticizers will have lower gas and heat production and should be more abuse tolerant. Cells made with geUed electrolytes, if the organic liquids are similar or identical to those used in liquid electrolyte cells, should have a similar safety response. 

Fig. 5.12 Stability testing of (a) the electrospun PVDF-HFP nanofiber electrolyte cells, (b) the liquid electrolyte cells, and (c) the soaked electrospun PVDF-HFP nanofiber after 36 h (Reprinted from Park et al. [93]. Copyright 2011 with permission from Elsevier)...

The trend of Figure 7 demonstrates that the voltage profile and the cycling capacity (about 130 mAh-g ) match those expected for this cathode material in liquid electrolyte cells. Furthermore, the electrode can be extensively cycled with a contained capacity loss (see Figure 8). Similar results have been obtained with other lithium metal oxides, e.g., LiNiYCo .y)02 [29] this finally demonstrating the compatibility of the gel membranes with the most common Uttiium ion cathode materials. 

Liquid electrolyte cells Solid electrolyte cells... 

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