Characterization of Separators

The key properties of separators are summarized in Table 2. Table 3 gives some typical values for Celgard membranes. Currently, 25 im is the most widely 

Permeability Electrical resistivity, voltage drop, air flow  

Porosity Calculated from dimension.s, basis wt., and skeletal density  

Chemical composition Atomic absorption, differenlial scanning calorimetry, others  

Thermal stability Hot electrical resistivity, thermal-mechanical analysis  

The Celgard microporous materials made by Polypore Corporation are the best-characterized battery separators. Bierenbam et al. [49] describe the process. 

Permeability Porosity Pore size Thickness Chemical composition Thermal stability Mechanical strength Electrical resistivity, voltage drop, air flow Calculated from dimensions, basis weight, and skeletal density Image analysis, Hg porometry Micrometer Atomic absorption, differential scanning calorimetry, others Hot electrical resistivity, thermal-mechanical analysis Tensile properties, puncture strength 

Currently, 20 pm is the most widely used thickness for Hthium ion battery separators. Single layers can be made as thin as 7 pm or as thick as 40 pm. The thicker the separator, the greater is the mechanical strength and the lower the probability of punctures during cell assembly, but the smaller is the amount of active materials that can be placed in the can. The uniformity of thickness is important so that the jeUyroll (that is, the spirally wound electrodes and separator) will fit into a can.  

The mechanical strength of a separator is characterized in terms of tensile properties and puncture strength. Tensile strength measurements (e.g.. Young s modulus, 2% offset strength, elongation at break, stress at break) can be made 

4) Uniformity of thickness is very important for uniform charging and discharging of the cell. 

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A typical application is given by Debets et al. A quality criterion for the characterization of separation in a chromatogram is modified by using Hermite polynomial coefficients in order to enhance the performance. The quality criterion can be used in... 

CHARACTERIZATION OF SEPARATED SAMPLES Figure 12. Diagram of the differential sublimation apparatus... 

Novales-Li P, Priddle JD. 1995. Production and characterization of separate monoclonalantibodies to human brain and erythrocyte acetylcholinesterases. Hyhridoma 14 67-73. 

This section introduced characterization of inertial microfiuidic separation using microparticles. The visualization of separation using pPSV and the analysis of efficiency and purity provide both qualitative and quantitative results supporting the characterization of separation in inertial microfluidics. This section offers a simple guide for characterizing separations, as well as in the design and optimization of inertial microfiuidic devices. 

Characterization of Mkrofluidic Devices Using Microparticles, Fig. 6 Characterization of separation, (a) Fluorescent images and concentrations of collections from the control (inlet sample) and the three outlets... 

Shirai, H., Spotnitz, R., Atsushi, A. Characterization of Separators for Lithium Ion Batteries -A Review, Chemical Industry, 48 (1997) 47 (in Japanese)... 

Ryll T, Dutina G, Reyes A, Gunson J, Krummen L, Etcheverry T. (2000) Performance of small-scale CHO perfusion cultures using an acoustic cell filtration device for cell retention characterization of separation efficiency and impact of perfusion on product quahty. Biotechnol. Bioeng., 69 440-449. 

Shirai H, Spotnitz R, Atsushi A (1997) Characterization of separators for lithium ion batteries - a review. Chem Ind 48 47 (in Japanese)... 

The obvious method of characterization of separation capability of air classifiers is by using the cut size concept. Ideally, all particles below the cut size would end up in the fines stream while all particles above the cut size would follow the coarse stream. However, there will be always misplaced material, that is, a small fraction of particles smaller than the cut size would be in the coarse stream and an equally small proportion of particles larger than the cut size would appear in the fines stream. The extent of the overlap due to misplaced material, as well as the cut size, can be determined by measuring the particle size distributions of both streams, and presenting their data as a weight frequency distribution. The yields of fines Yf and coarse Y streams need to be identified. When they are equal, the point of overlap gives the cut size. When they are not equal, which is most likely, the frequency distribution for the fines stream must be multiplied by the yield for the fines stream, while the yield for the coarse stream must be multiplied by the yield for the coarse stream. The cut size is, thus, given by the point of intersection of these curves. 

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