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Significance and Use
Nickel metal hydride (Ni-MH) cells/batteries can exhibit high self-discharge rates. Nitrate impurities in the positive electrode can be reduced to ammonia on the negative electrode. This causes rapid self-discharge. Technical publications have reported a link between the separator ammonia trapping capabilities and the cells charge retention. Grafted polyolefin separators can absorb or trap these impurities—hence, reducing self-discharge rates. The level of ammonia trapping from this method gives an indication of the efficiency of a separator to trap these contaminates, thus helping a battery self discharge ( charge retention). A higher value should allow a cell to have greater charge retention.
1.1 This test method covers the measurement of the ability of a material to capture ammonia.
1.2 This test method is intended primarily for testing grafted polyolefin materials used as a battery separator, although other materials could be tested.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
D123 Terminology Relating to Textiles
E438 Specification for Glasses in Laboratory Apparatus
E1272 Specification for Laboratory Glass Graduated Cylinders
ICS Number Code 29.220.01 (Galvanic cells and batteries in general)
UNSPSC Code 26111700(Batteries and cells and accessories)
ASTM D7129-09, Standard Test Method for Determination of Ammonia Trapping in a Grafted Battery Separator, ASTM International, West Conshohocken, PA, 2009, www.astm.orgBack to Top