ASTM D7148-07
(Test Method)Standard Test Method for Determining the Ionic Resistivity (ER) of Alkaline Battery Separator Using a Carbon Electrode in an Electrolyte Bath Measuring System
Standard Test Method for Determining the Ionic Resistivity (ER) of Alkaline Battery Separator Using a Carbon Electrode in an Electrolyte Bath Measuring System
SIGNIFICANCE AND USE
The ER of a battery separator is a standard measurement used by separator and battery manufacturers for quality control purposes and separator selection.
Separator ER and the separator’interaction with the electrolyte, that is resistance to wetting or flow, will contribute to the internal resistance of the battery and this can potentially limit the electrical output of a battery. The ER determination is a tool for battery manufacturers to use in design, material selection, and performance specifications.
The change in the bath electrical resistance imparted by a separator is affected by the porosity, thickness, and tortuousity of the pore structure of the separator, the wettability of the separator to the electrolyte, and the temperature and concentration of the electrolyte.
Incomplete wetting or saturation of the pore structure limits the lowest ER value obtainable from a separator structure. Separators are pretreated to assure that the specimen being tested has been adequately wetted out. A separator that is not fully wetted out (saturated) will give a higher ER.
This test method is intended to give a rapid and repeatable measurement that approximates the change in ER that could happen when the separator is used in a battery.
SCOPE
1.1 This test method covers the pretreatment, test conditions, apparatus, and procedure to determine the ionic resistivity, commonly referred to in the battery industry as electrical resistance (ER) of an alkaline battery separator immersed in an electrolyte of 40 % potassium hydroxide (KOH).
1.2 The values stated in SI units are to be regarded as the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
An American National Standard
Designation:D7148–07
Standard Test Method for
Determining the Ionic Resistivity (ER) of Alkaline Battery
Separator Using a Carbon Electrode in an Electrolyte Bath
Measuring System
This standard is issued under the fixed designation D7148; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 barrier resistance (RB), n—the resistance of the bath
with a solid, nonporous sheet of alkaline resistant, electrical
1.1 This test method covers the pretreatment, test condi-
insulation that separates the electrodes.
tions, apparatus, and procedure to determine the ionic resistiv-
3.1.2 bath resistance (RC), n—the resistance of the bath
ity, commonly referred to in the battery industry as electrical
without the specimen (separator).
resistance (ER) of an alkaline battery separator immersed in an
3.1.3 bath resistance (RT), n—the total electrical resistance
electrolyte of 40 % potassium hydroxide (KOH).
of the bath and a separator specimen.
1.2 The values stated in SI units are to be regarded as the
3.1.4 battery separator, n—an ion-permeable, nonconduc-
standard.
tivematerialthatpreventselectricalcontactbetweenelectrodes
1.3 This standard does not purport to address all of the
of opposite polarity.
safety concerns, if any, associated with its use. It is the
3.1.5 electrolyte, n—a 40 % potassium hydroxide solution.
responsibility of the user of this standard to establish appro-
3.1.6 ionic resisitivity (ER), n—the product of a change in
priate safety and health practices and determine the applica-
electrical resistance times an area.
bility of regulatory limitations prior to use.
3.1.6.1 Discussion—Theareaistheapertureareadividedby
2. Referenced Documents
thenumberofseparatorsbetweentheelectrodes.Thechangein
resistance is the difference, in ohms, of the electrical resistance
2.1 ASTM Standards:
with and without the seperator(s). The SI units for ER are
D1711 Terminology Relating to Electrical Insulation
ohms-metre but the customary practice in the battery industry
2.2 Battery Council International:
istoreporttheERinunitsofohms-cm .Itshouldbenotedthat
Standard Test Method for Determining the Electrical Resis-
this terminology is not in conflict with Terminology D1711.
tance of a Battery Separator Using a Palico Measuring
3.2 Symbols:
System, Section 3.3b
3.2.1 ER—a symbol, peculiar to the battery industry, denot-
3. Terminology
ing that characteristic of a sheet material that is related to the
rate of transfer of ions through the interstices of a porous sheet
3.1 Definitions of Terms Specific to This Standard:
immersed between two carbon electrodes in an aqueous
electroyte.
This test method is under the jurisdiction of ASTM Committee D09 on
4. Summary of Test Method
Electrical and Electronic Insulating Materials and is the direct responsibility of
Subcommittee D09.19 on Dielectric Sheet and Roll Products.
4.1 This test method detects small changes in ohmic resis-
Current edition approved Jan. 1, 2007. Published February 2007. DOI: 10.1520/
tance between carbon electrodes immersed in an alkaline
D7148-07.
electrolyte with and without separator material between the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
carbon electrodes. This change is related to the rate of transfer
Standards volume information, refer to the standard’s Document Summary page on
of ions through a separator material.The ER is calculated from
the ASTM website.
3 th the fixed aperture area. The sensitivity and resolution of the
AvailablefromBatteryCouncilInternational,401N.MichiganAve.,24 Floor,
Chicago, IL 60611-4267. apparatus detects electrical resistance changes of 6 0.1 %.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7148–07
5. Significance and Use tions. Enclose the glass-mixing bottle in a plastic container of
sufficient capacity to contain the solution in case of bottle
5.1 TheERofabatteryseparatorisastandardmeasurement
breakage.Topreventexcessiveheating,addconcentratedKOH
used by separator and battery manufacturers for quality control
slowly to water with adequate agitation to produce thorough
purposes and separator selection.
mixing. The diluted KOH is sufficiently corrosive at both
5.2 Separator ER and the separator’s interaction with the
ambient and elevated temperatures that careful handling is
electrolyte, that is resistance to wetting or flow, will contribute
necessary to prevent injury or damage.
to the internal resistance of the battery and this can potentially
8.2 The hazard associated with mixing KOH with water is
limit the electrical output of a battery. The ER determination is
that it generates a lot of heat as it dissolves; this has the
a tool for battery manufacturers to use in design, material
potential to lead to spattering. A concentrated KOH solution
selection, and performance specifications.
willerodeskinandeyes.Avoidthesehazardsbywearingsafety
5.3 The change in the bath electrical resistance imparted by
glasses, face shield, and protective gloves, and immediately
a separator is affected by the porosity, thickness, and tortu-
rinsing with water if any skin contact occurs. (If any eye
ousity of the pore structure of the separator, the wettability of
contact occurs, flush the eyes with water for 15 min and then
the separator to the electrolyte, and the temperature and
get medical attention.)
concentration of the electrolyte.
5.4 Incomplete wetting or saturation of the pore structure
9. Sampling, Test Specimens, and Test Units
limits the lowest ER value obtainable from a separator struc-
9.1 Select samples representative of the separator material
ture. Separators are pretreated to assure that the specimen
to be tested.
being tested has been adequately wetted out.Aseparator that is
9.2 Use a specimen size of at least 120 by 120 mm and no
not fully wetted out (saturated) will give a higher ER.
larger than what will fit in the bath.
5.5 This test method is intended to give a rapid and
9.3 If specimens require identification, use an alkaline
repeatable measurement that approximates the change in ER
resistant marker. Mark an area of the specimen that will not
that could happen when the separator is used in a battery.
interfere with the ion transfer through the separator.
6. Apparatus
10. Preparation of Apparatus
6.1 Stainless steel container or equivalent to accommodate
10.1 Fill the ER bath with prepared battery electrolyte (40
the separator test samples.
6 1 %KOHsolution)toalevelabovetheapertureopening(12
6.2 Hot plate or other heating device suitable to boil water.
to 25 mm below the top of the ER bath). Adjust the bath’s
6.3 Stainless steel screen.
temperature to 25 65°C.
6.4 Glass or plastic separator tank for presoaking separators
10.2 Connect the electrodes to the resistance meter control
in battery electrolyte.
unit using alkali-resistant wire and hardware.
6.5 Interval timer.
10.3 Turn on the resistance meter. Allow the equipment to
6.6 Safety glasses.
stabilize for at least 20 min. If the meter includes a standard
6.7 Thermometer.
reference resistor (place in “Standby” mode and “Standard”
6.8 Alkaline resistant gloves, that is neoprene latex or
scaling on the resistance meter control unit and set to the
polyethylene gloves.
appropriate resistance range scale for a 0.200-V resistor
6.9 Plastic tongs for handling KOH-wetted separators.
reading). Unless the meter reading is within 6 0.1 % of the
6.10 ER bath with a fixed aperture area (32 cm is standard)
value of the resistor, service will be required.
that puts a uniform current flux through a fixed area of the
10.4 If available, check the resistance standard for the
separator sample for measurement.Adrawing of an ER bath is
systemoutlinedin11.4.Ifthisagreeswithin 6 1 %,proceedto
included in Annex A1.
Section 13.
6.11 A.C. resistance meter or bridge with sufficient sensi-
10.5 Periodically, or when problems occur or changes are
tivityandresolutiontomeasure 60.1 %changeintheERbath
made to the system, test the stability, polarization, current
resistance in the presence of potentials generated in the ER
leakage, and standardizati
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.