ASTM D7148-2013 0161 Standard Test Method for Determining the Ionic Resistivity &40 ER&41 of Alkaline Battery Separator Using a Carbon Electrode in an Electrolyte Bath Measuring Sy.pdf

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1、Designation: D7148 13 An American National StandardStandard Test Method forDetermining the Ionic Resistivity (ER) of Alkaline BatterySeparator Using a Carbon Electrode in an Electrolyte BathMeasuring System1This standard is issued under the fixed designation D7148; the number immediately following t

2、he designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers

3、 the pretreatment, testconditions, apparatus, and procedure to determine the ionicresistivity, commonly referred to in the battery industry aselectrical resistance (ER) of an alkaline battery separatorimmersed in an electrolyte of 40 % potassium hydroxide(KOH).1.2 The values stated in SI units are t

4、o be regarded as thestandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations

5、 prior to use.2. Referenced Documents2.1 ASTM Standards:2D1711 Terminology Relating to Electrical Insulation2.2 Battery Council International:Standard Test Method for Determining the Electrical Resis-tance of a Battery Separator Using a Palico MeasuringSystem, Section 3.3b33. Terminology3.1 Definiti

6、ons of Terms Specific to This Standard:3.1.1 barrier resistance (RB), nthe resistance of the bathwith a solid, nonporous sheet of alkaline resistant, electricalinsulation that separates the electrodes.3.1.2 bath resistance (RC), nthe resistance of the bathwithout the specimen (separator).3.1.3 bath

7、resistance (RT), nthe total electrical resistanceof the bath and a separator specimen.3.1.4 battery separator, nan ion-permeable, nonconduc-tive material that prevents electrical contact between electrodesof opposite polarity.3.1.5 electrolyte, na 40 % potassium hydroxide solution.3.1.6 ionic resisi

8、tivity (ER), nthe product of a change inelectrical resistance times an area.3.1.6.1 DiscussionThe area is the aperture area divided bythe number of separators between the electrodes. The change inresistance is the difference, in ohms, of the electrical resistancewith and without the seperator(s). Th

9、e SI units for ER areohms-metre2but the customary practice in the battery industryis to report the ER in units of ohms-cm2. It should be noted thatthis terminology is not in conflict with Terminology D1711.3.2 Symbols:3.2.1 ERa symbol, peculiar to the battery industry, denot-ing that characteristic

10、of a sheet material that is related to therate of transfer of ions through the interstices of a porous sheetimmersed between two carbon electrodes in an aqueouselectroyte.4. Summary of Test Method4.1 This test method detects small changes in ohmic resis-tance between carbon electrodes immersed in an

11、 alkalineelectrolyte with and without separator material between thecarbon electrodes. This change is related to the rate of transferof ions through a separator material. The ER is calculated fromthe fixed aperture area. The sensitivity and resolution of theapparatus detects electrical resistance ch

12、anges of 60.1 %.1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.19 on Dielectric Sheet and Roll Products.Current edition approved Nov. 1, 2013. Published January 2014. Last previous

13、edition approved in 2011 as D714807(2011). DOI: 10.1520/D7148-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM webs

14、ite.3Available from Battery Council International, 330 N. Wabash Ave., Ste. 2000,Chicago, IL 60611.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 The ER of a battery separator is a standard measurementused

15、by separator and battery manufacturers for quality controlpurposes and separator selection.5.2 Separator ER and the separators interaction with theelectrolyte, that is resistance to wetting or flow, will contributeto the internal resistance of the battery and this can potentiallylimit the electrical

16、 output of a battery. The ER determination isa tool for battery manufacturers to use in design, materialselection, and performance specifications.5.3 The change in the bath electrical resistance imparted bya separator is affected by the porosity, thickness, and tortuous-ity of the pore structure of

17、the separator, the wettability of theseparator to the electrolyte, and the temperature and concen-tration of the electrolyte.5.4 Incomplete wetting or saturation of the pore structurelimits the lowest ER value obtainable from a separator struc-ture. Separators are pretreated to assure that the speci

18、menbeing tested has been adequately wetted out.Aseparator that isnot fully wetted out (saturated) will give a higher ER.5.5 This test method is intended to give a rapid andrepeatable measurement that approximates the change in ERthat could happen when the separator is used in a battery.6. Apparatus6

19、.1 Stainless steel container or equivalent to accommodatethe separator test samples.6.2 Hot plate or other heating device suitable to boil water.6.3 Stainless steel screen.6.4 Glass or plastic separator tank for presoaking separatorsin battery electrolyte.6.5 Interval timer.6.6 Safety glasses.6.7 Th

20、ermometer.6.8 Alkaline resistant gloves, that is neoprene latex orpolyethylene gloves.6.9 Plastic tongs for handling KOH-wetted separators.6.10 ER bath with a fixed aperture area (32 cm2is standard)that puts a uniform current flux through a fixed area of theseparator sample for measurement.Adrawing

21、of an ER bath isincluded in Annex A1.6.11 A.C. resistance meter or bridge with sufficient sensi-tivity and resolution to measure 60.1 % change in the ER bathresistance in the presence of potentials generated in the ERbath.7. Reagents and Materials7.1 Distilled or deionized water.7.2 Reagent grade KO

22、H.8. Hazards8.1 Safety goggles and face shield, lab coat, and rubberapron and gloves must be worn during KOH dilution opera-tions. Enclose the glass-mixing bottle in a plastic container ofsufficient capacity to contain the solution in case of bottlebreakage.To prevent excessive heating, add concentr

23、ated KOHslowly to water with adequate agitation to produce thoroughmixing. The diluted KOH is sufficiently corrosive at bothambient and elevated temperatures that careful handling isnecessary to prevent injury or damage.8.2 The hazard associated with mixing KOH with water isthat it generates a lot o

24、f heat as it dissolves; this has thepotential to lead to spattering. A concentrated KOH solutionwill erode skin and eyes.Avoid these hazards by wearing safetyglasses, face shield, and protective gloves, and immediatelyrinsing with water if any skin contact occurs. (If any eyecontact occurs, flush th

25、e eyes with water for 15 min and thenget medical attention.)9. Sampling, Test Specimens, and Test Units9.1 Select samples representative of the separator materialto be tested.9.2 Use a specimen size of at least 120 by 120 mm and nolarger than what will fit in the bath.9.3 If specimens require identi

26、fication, use an alkalineresistant marker. Mark an area of the specimen that will notinterfere with the ion transfer through the separator.10. Preparation of Apparatus10.1 Fill the ER bath with prepared battery electrolyte (406 1 % KOH solution) to a level above the aperture opening (12to 25 mm belo

27、w the top of the ER bath). Adjust the bathstemperature to 25 6 5C .10.2 Connect the electrodes to the resistance meter controlunit using alkali-resistant wire and hardware.10.3 Turn on the resistance meter. Allow the equipment tostabilize for at least 20 min. If the meter includes a standardreferenc

28、e resistor (place in “Standby” mode and “Standard”scaling on the resistance meter control unit and set to theappropriate resistance range scale for a 0.200- resistorreading). Unless the meter reading is within 60.1 % of thevalue of the resistor, service will be required.10.4 If available, check the

29、resistance standard for thesystem outlined in 11.4. If this agrees within 61 %, proceed toSection 13.10.5 Periodically, or when problems occur or changes aremade to the system, test the stability, polarization, currentleakage, and standardization using the maintenance proceduresset forth in Section

30、11.11. Testing and Maintenance of Equipment11.1 Stability of Equipment11.1.1 Check the resistance of the ER bath (Place the meterin “Operate” mode and “Standard” scaling and press “Reset.”Set the appropriate resistance range to give the maximummeter reading without going off scale.).D7148 13211.1.2

31、Agitate the electrolyte to make certain that thetemperature and concentration are uniform.11.1.3 Ensure the bath resistance (RC) is constant within60.5 % at a given temperature and electrolyte concentration.11.1.4 If readings are inconsistent, proceed to 11.2 and 11.3for polarization and leakage det

32、ermination.11.2 Polarization of Equipment11.2.1 Polarization affects the reading of any resistancemeasuring system differently. Follow manufacturer instruc-tions.11.2.2 For the resistance measuring system, place the resis-tance unit in “Operate” mode and “Standard” scaling and press“Reset.”11.2.3 Se

33、t the appropriate resistance range to give themaximum meter reading (RC) without going over scale.11.2.4 Press “Test Offset.” If the reading is higher thanmidrange of the set value then the polarization is too high.11.2.5 If the polarization is above the maximum, allow 30min for stabilization or dis

34、charge, or both. Then repeat mea-surement.11.2.6 If the polarization persists, change the electrolyte andclean the electrodes.11.3 Leakage Current11.3.1 If the test bath has warped or cracked, it can haveleakage currents, and potentially affect the ER value measured.Check the bath periodically, when

35、ever the electrolyte ischanged or if the bath is moved by using the followingprocedure:11.3.1.1 Insert a thin solid sheet of alkali-resistant solidflexible nonporous plastic (such as polyethylene) that has thesame dimensions as the separator specimen. Close the gatesnugly against the plastic sheet.

36、Adjust the resistance range ofthe meter to obtain the fullest scale reading possible and recordas the barrier resistance (RB). It is possible that the reading willrise after the gate is closed.Wait until the readings are constant.11.3.1.2 Remove the barrier sheet and measure the bathresistance (RC).

37、11.3.1.3 If the ratio of RC/RB is greater than 0.07, bathmaintenance or replacement is required. In the ER bath, thisratio can be reduced by sealing the leaks or cracks in thepartitions.Abath with sealed partitions is harder to clean but ismore stable electrically and mechanically.11.4 Standardizati

38、on11.4.1 If available, insert a porous plastic sheet that has beenstandardized for the ER bath into the test area and close theslide. Read the bath resistance with the sheet in place (RT).11.4.2 Remove the sheet without moving the slide and readthe resistance of the bath (RC) without moving the slid

39、e.11.4.3 Ensure that the difference between these two read-ings times the aperture area is equal to the measured standardwithin 61 % corrected for temperature in 14.1.11.4.4 In the resistance measuring system, it is possible toset the meter to “Scaled” mode and to press the “Preset” switchwith the p

40、lastic standard in the test area with a closed slide.When the standard is removed, ensure that the reading on themeter equals the standardized value within 61 % when cor-rected for temperature.11.4.5 Clean the surfaces of the bath and the surroundingsafter each use to remove spilled electrolyte on t

41、he surfaces andconnections. Ensure that the resistance meter is far enoughfrom the KOH bath to prevent fumes from corroding the meter.Check and if necessary adjust the electrolyte to the properconcentration before each use. If polarization contaminantsbegin to affect the reading, replace the electro

42、lyte. To preventcracking or crazing of the plastic bath, avoid adding hotelectrolyte or mixing concentrated alkali in the bath.11.4.6 If the bath must be dried for shipment, storage, oranother reason, pour the electrolyte out and refill the bath withdeionized water. Allow it to stand for 24 h. Then

43、drain it andallow it to dry at room temperature. This will minimize thechance of cracking or crazing of the baths plastic walls.12. Specimen Conditioning12.1 Use specimen as received. If samples are hydrophobic,use a prewetting procedure.13. Procedure13.1 Measure the temperature of the electrolyte i

44、n the ERbath. If the temperature is not within 25 6 5C, adjust the bathtemperature.13.2 Remove the pretreated specimens from the separatorstorage tank and insert the specimens into the test area of theER bath.13.3 Tap the separator specimens to remove any air bubblesclinging to the surfaces.13.4 Car

45、efully close the gate against the separator, so thatthe separator can be removed without moving the gate.Measure the total resistance of the bath and the separators.Record as RT. If the resistance drifts, wait until the unitfluctuates over the same range and then record the mean valueof the range. F

46、or the resistance meters control unit, press the“Reset” switch and then the “Preset” switch. Repeat if themeter does not zero out.13.5 Remove the specimen and remeasure the resistance ofthe bath (RC) with no separators. Important: do not move thegate. For the resistance meter control unit with the “

47、Preset”option, the reading after removing the separators directly givesthe difference (RT-RC) used in the calculations in 14.1.13.6 If the resistance meter controls uses a “Scaled” setting,the appropriate aperture area is automatically multiplied timesthe meter reading. If the unit is in the “Standa

48、rd” mode,aperture calculations shall be made manually13.7 Repeat this procedure for the remaining specimens.D7148 13314. Calculation or Interpretation of Results14.1 ionic resistivity (ER)ionic resistivity ER!5 (1)RT 2 RC! 3Aperture AreaNo. of separator specimenswhere:RC = the bath resistance obtain

49、ed in 13.5, andRT = the total resistance of the bath and separators obtainedin 13.5.14.2 If the resistance meter control unit uses the “Scaled”setting and the “Preset” feature, the appropriate aperture area isautomatically multiplied times the reading and the calculationis simply:ionic resistivity ER!5 (2)Meter Reading3CFNo. of separator samples14.2.1 Units for ER are (ohms) area (cm2) and aretypically reported as units of “ohm-cm2.”14.2.2 Report the pretreatment method used, such as “20-min soak” or “boiled” and the aperture size of the ER bath andthe number of