1、 SURFACE VEHICLE RECOMMENDED PRACTICE J3042 FEB2015 Issued 2015-02 Measuring Properties of Li-Battery Electrolyte RATIONALE As the market for Li-batteries continues to grow due to the evolution of motive and stationary power applications, new electrolyte concepts are being proposed for incorporation
2、 into these batteries. There are a variety of properties that could be measured and a variety of methodologies to perform testing. This Recommended Practice (RP) provides a set of test methods for the characterization of the Li-battery electrolyte, which if used consistently across different materia
3、ls, will facilitate the comparison of the properties of Li-battery electrolyte. An electrolyte is defined as the medium that provides ion transport between the positive and negative electrodes of a cell. (SAE J1715/2) TABLE OF CONTENTS 1. Scope . 2 2. References. 2 3. Definitions 3 4. Sample prepara
4、tion . 3 5. Chemical content (Lithium, impurities) 4 6. Water content 4 7. Free acid (Neutralization) 4 8. Color (APHA value) . 4 9. Density / Specific gravity 5 10. Viscosity . 5 10.1 Dynamic Viscosity (also known as absolute viscosity or shear viscosity) . 5 10.2 Kinematic Viscosity 5 11. Ionic Co
5、nductivity . 6 12. Thermal stability . 6 12.1 Differential Scanning Calorimetry (DSC) . 6 12.2 Accelerating Rate Calorimetry (ARC) 7 13. Flammability . 7 14. Flash point . 7 _ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and eng
6、ineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it ma
7、y be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2015 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical
8、, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To p
9、rovide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J3042_201502 SAE INTERNATIONAL J3042 Issued FEB2015 Page 2 of 9 15. Voltage stability (as a function of temperature): 7 16. NOTES . 9 16.1 Marginal Indicia 9 1. SCOPE This SAE RP provides a set of test metho
10、ds and practices for the characterization of the properties of Li-battery electrolyte. It is not within the scope of this document to establish criteria for the test results, as this is usually established between the vendor and customer. 2. REFERENCES 2.1 Applicable Document The following publicati
11、ons form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or
12、 724-776-4970 (outside USA), www.sae.org. SAE J1715/1 Hybrid Electric Vehicle (HEV) discuss with the KF titrant supplier to select an appropriate titrant. 7. FREE ACID (NEUTRALIZATION) Potentiometric titration method (i.e., neutralization titration), as described in ASTM D664-11a is recommended for
13、the measurement of free acid (e.g., hydrofluoric acid), with the following comments: ASTM D664-11A provides guidelines regarding sample preparation which may not be applicable to electrolytes. The user should prepare samples according to the manufacturers recommended guidelines and/or modify the sam
14、ple preparation methods so that free acid amount does not increase as a consequence of the measurement system (e.g., solvent selection). If there is no manufacturers recommended titration systems/practice, then the user should evaluate the contribution of each component of the electrolyte separately
15、, to determine if there is potential interference as a result of reaction with the titration system. If a component is not compatible with the titrant system, as could be evidenced by the inability to reach endpoint stabilization, then alternative titrants and/or solvents should be explored. 8. COLO
16、R (APHA VALUE) The color of electrolyte is measured by comparison to known color reference materials or by correlation of spectroscopic response upon controlled illumination. Color is an indication of potential product degradation. ASTM D1209-05 describes a procedure for the visual measurement of co
17、lor for light colored liquids. The color of the liquid is compared to the color of platinum-cobalt standard solutions. ASTM D5386-10 describes an instrumental method for the measurement of the color of near clear liquid samples. The measured color is converted to a color rating of the platinum-cobal
18、t scale. This is the preferred method due to the less subjective nature of the analysis and better precision. SAE INTERNATIONAL J3042 Issued FEB2015 Page 5 of 9 Prepare samples per manufacturers guidelines 9. DENSITY / SPECIFIC GRAVITY Density is often measured from the direct measurement of sample
19、mass of a known fixed volume of sample. Note: Density and specific gravity values should only be compared when conducted at the same measurement temperature (1 C). Most electrolytes will generate hydrofluoric acid (HF) in the presence of water. It is not expected that HF generation would significant
20、ly change the measured density of the electrolyte: however, the generated HF could damage equipment. ASTM D891-09 describes a method of determining specific gravity of a liquid by pycnometry. The volume of the material is held constant by the measurement system, and when combined with the measured m
21、ass, allows for the calculation of density. The method provides for using the same sample tube to first measure the volume of the pycnometer with water (using the known density of water as a function of measurement temperature to calculate the volume from the measured mass of water) ASTM D4052-11 de
22、scribes an instrumental method of determining density and specific gravity of a liquid by introducing the liquid into an oscillating sample tube. This method uses the change in oscillation frequency caused by the change of the mass of the tube to determine density. 10. VISCOSITY Viscosity is often d
23、etermined by measuring the flow properties of materials in relation to a reference material. Viscosity varies as a function of temperature. The user should record the temperature at which the measurement is performed. For situations where users are trying to evaluate whether an electrolyte would be
24、appropriate for an application, the users should evaluate the sensitivity of viscosity at select temperature points within the expected temperature operating regime. If a temperature bath is used to maintain the test temperature (per section 4.4), the user should use an aprotic solvent with low vapo
25、r pressure within the temperature range of interest; further, the solvent must remain liquid within the temperature range. NOTE: To characterize the material under a controlled shear, dynamic viscosity should be used. If shear does not need to be controlled, kinematic viscosity techniques can be use
26、d. Kinematic techniques are generally applied to Newtonian fluids. 10.1 Dynamic Viscosity (also known as absolute viscosity or shear viscosity) Absolute viscosity, or the coefficient of absolute viscosity, is a measure of the kinematic resistance. Dynamic (absolute) viscosity is the tangential force
27、 per unit area required to move one horizontal plane with respect to the other at unit velocity when maintained a unit distance apart by the fluid. ASTM D7867 describes a method of determining viscosity using rotational techniques. 10.2 Kinematic Viscosity Kinematic viscosity is the ratio of absolut
28、e or dynamic viscosity to density; it is a quantity in which no force is involved. ASTM D445-12 describes the general methodology for determining kinematic viscosity. ASTM D7042-12a applies the methods of D455-12 within a specific instrument. For either D445-12 or D7042-12, solvents used for cleanin
29、g of the apparatus should be miscible with electrolyte. ISO 3104 (1999), which describes a method for determining kinematic viscosity and the calculation of dynamic viscosity, is offered as an alternative to the ASTM documents referenced above. SAE INTERNATIONAL J3042 Issued FEB2015 Page 6 of 9 11.
30、IONIC CONDUCTIVITY Ionic conductivity is typically determined by measuring the alternating current resistance of a material between two electrodes. Conductivity varies as a function of temperature. The user should record the temperature at which the measurement is performed. The methods described in
31、 ASTM D1125-95 (2009) are generally recommended, with consideration for the following: The temperature bath should not use water. The bath should contain an aprotic solvent with low vapor pressure within the temperature range of interest; further the solvent must remain liquid within the temperature
32、 range. Equipment preparation should allow for parts that contact the electrolyte to be dried. Solvents used for cleaning of the apparatus should be miscible with electrolyte. Formation of hydrofluoric acid (HF) due to exposure to moisture could cause variability in the measured conductivity. If the
33、 user observes atypical variability in the conductivity measurement, he/she should consider placing the equipment in dry box/dry room. For situations where users are trying to evaluate whether an electrolyte would be appropriate for an application, the users should evaluate the sensitivity of conduc
34、tivity at select temperature points within the expected temperature operating regime. For example, electrolyte developed for automotive applications should, at a minimum, have conductivity measured between -30 C and 60 C; alternately, in a quality control situation, conductivity may only need to be
35、measured at one temperature. 12. THERMAL STABILITY Thermal stability is typically determined by monitoring changes in the physical properties of a material as a function of temperature. NOTE: The thermal stability of the material by itself will not provide a complete picture of the thermal stability
36、 of a full cell. NOTE: Samples must be prepared in an inert, dry environment. 12.1 Differential Scanning Calorimetry (DSC) ASTM E537-12 provides general information on the usefulness of the technique and operating principles. The DSC measures heat flow to and from a sample as a function of temperatu
37、re. As a result, it can measure thermal energy generated by the reaction of electrode with electrolyte. A hermetically sealed pan should be used to prevent reaction of electrolyte with air (particularly water). The pan will open when gaseous components cause sufficient increase in pressure; therefor
38、e temperature data beyond this point is no longer meaningful. As hermetic pans can open energetically, users are cautioned to perform a careful review of the experimental setup, including compatibility of the different materials. Ideally, this test should be performed in equipment that is housed in
39、an enclosure. NOTE: ASTM E537-12 section 12.3 briefly discusses self-pressurization of the hermetic container and the impact of increased partial pressure on the enthalpy. The increased partial pressure is a drawback to using this technique Recommended test parameters: Initial sample size: 10 to 50
40、mg (follow instructions for particular instrument) Temperature range: 25 to 400 C Temperature ramp: 1 C/min SAE INTERNATIONAL J3042 Issued FEB2015 Page 7 of 9 12.2 Accelerating Rate Calorimetry (ARC) ASTM E1981-98 provides general information on the usefulness of the technique and operating principl
41、es. ARC is an adiabatic system which increases sample temperature at a user set heating rate until an exothermic reaction is detected, at which point the heat flow out of the sample is measured. The user should make judicious choices for: o initial temperature setpoint o self-heating rate (SHR), and
42、 o heat/wait/search (HWS) profile Only data measured under the same conditions/parameters will be comparable. ARC units can be equipped with pressure relief systems, which will avoid the partial pressure change observed when performing DSC measurements in hermetic systems. ARC data can generally be
43、correlated to DSC data. 13. FLAMMABILITY Flammability of a material is typically determined by monitoring a substance for evidence of combustion as a function of temperature and concentration. ASTM E918 describes methods for the determination of the lower and upper concentration limits of flammabili
44、ty of vapor-oxidant mixtures at temperatures up to 200oC. This method provides a method for introducing a liquid fuel into the test chamber. ASTM E681, while similar to ASTM E918, looks at the lower and upper concentration limits of flammability of chemicals with sufficient vapor pressure to form fl
45、ammable mixtures in air at atmospheric pressure at the test temperature. 14. FLASH POINT The flash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a flash point requires an ignition source. At the flash point, the vapor m
46、ay cease to burn when the source of ignition is removed. NOTE: Since lithium battery electrolyte salts react with water, open cup measurement techniques are not recommended for measuring the flash point of electrolyte. NOTE: Tthe flash point of a material is an empirical measurement rather than a fu
47、ndamental physical parameter. The measured value will vary with equipment and test protocol. There are different types of closed cup testers. When reporting flash point results, the user should also report the flash point method used (i.e., Pensky-Martens Closed Cup, Tag Closed Cup, etc.). ASTM E502
48、-07 (2013), Standard test method for selection and use of ASTM standards for the determination of flash point of chemicals by closed cup method, provides general information on the usefulness of the technique and operating principles. 15. VOLTAGE STABILITY (AS A FUNCTION OF TEMPERATURE): Voltage sta
49、bility is the measurement of a stable voltage range for the electrolyte of interest in an ideal electrochemical cell configuration by monitoring current flow under controlled voltage conditions to determine where minimal electrolysis occurs. SAE INTERNATIONAL J3042 Issued FEB2015 Page 8 of 9 When conducting this measurement, the following conditions are recommended: The use of open
