1、SURFACE VEHICLERECOMMENDED PRACTICEJ3021 OCT2014Issued 2014-10Recommended Practice for Determining Material Properties of Li-Battery Cathode Active MaterialsRATIONALEAs the market for Li-batteries grows due to the evolution of motive and stationary power applications, new cathode active materials ar
2、e being proposed for incorporation into these batteries. These materials have a variety of measurable properties with a variety of testing methodologies to characterize their functionality. This recommended practice (RP)provides a set of test methods for the characterization of the Li-battery cathod
3、e active materials properties, which, if used consistently across different materials, will facilitate the comparison of the properties of cathode active materials.1. SCOPEThis SAE RP provides a set of test methods and practices for the characterization of the properties of Li-battery cathode active
4、 material.It is not within the scope of this document to establish criteria for the test results, as these are usually established between the vendor and customer.It is not within the scope of this document to examine the rheological properties of the cathode material in slurry since such properties
5、 are influenced by the conductive additive and the solid loading, which are determined through discussion between the manufacturer and user.It is not within the scope of this document to examine the electrochemical properties of cathode materials since these are influenced by electrode design. The c
6、ommittee considers that it is impossible to establish an electrode design that would be appropriate for all cathode active materials. 2. REFERENCES2.1 Applicable DocumentsThe following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the late
7、st issue of SAE publications shall apply.2.1.1 SAE PublicationsAvailable from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org.SAE J1715 Hybrid Electric Vehicle (HEV) REFERENCE RIETVELD)Purpose:
8、 Determine that the material has the desired crystal structure.Powder X-ray diffraction is recommended as the method to determine purity of the crystallographic structure. Both the positions (corresponding to lattice spacing) and the relative intensity of the measured intensity peaks are indicative
9、of a particular phase and material.NOTE: XRD cannot detect ppm levels of impurities or amorphous phases. Test parameters:x 2-Theta scan region from 10 to 90x At a maximum, the step size should be 0.05x A minimum signal to noise (S/N) ratio of 5 is recommended, where the signal to noise ratio is defi
10、ned as the peak signal intensity of the weakest peak of interest divided by the average signal intensity of the noise.NOTE: For R POWDER IN ELECTROLYTE)NOTE: The thermal stability of the material by itself or in electrolyte may not provide a complete picture of the thermal stability of a full cell.N
11、OTE: For the purposes of this document, the state of charge (SOC) of the active material is not changed. The material is tested as synthesized (generally, this means fully lithiated in the cathode of LiMO2, LiM2O4 and LiMXO4). To adjust SOC requires definition of electrode formulation, formation pro
12、tocols, instructions for cell assembly and disassembly and instructions on rinsing of electrodes to prevent changes to surface layers. Some of these procedures are material (electrode formulation, formation) dependent while others (rinsing while preventing damage to surface layer) are not yet define
13、d. As a result, procedures to modify the SOC of the materials are beyond the scope of this document. SAE INTERNATIONAL J3021 Issued OCT2014 Page 4 of 79.1 Thermogravimetric Analysis (TGA) (not to be used with electrolyte)ASTM E2550-11 (Standard test method for thermal stability by thermogravimetry)
14、provides general information on the usefulness of the technique and operating principles.Instrument heats the material at a constant rate until a desired final temperature is reached. The rate of temperature increase is set by the user. The atmosphere should be selected so that it is inert to the ma
15、terial (i.e., nitrogen or argon atmosphere).The instrument keeps a continuous record of the mass of the material in the sample pan. Any change to the material resulting in a change in mass will be detected. Test parameters:x Initial sample size: 10 to 50 mg (follow instructions for particular instru
16、ment)x Temperature range: 25 to 600 Cx Temperature ramp: 1 C/minIdeally, the gaseous species evolved from the sample, are routed to a mass spectrometer for identification. Alternately, post TGA analysis, such as XRD, could be used to identify crystalline phases in the resulting material and so indir
17、ectly help identify the evolved gaseous species. 9.2 Differential Scanning Calorimetry (DSC)ASTM E537-12 (Standard test method for the thermal stability of chemicals by differential scanning calorimetry) provides general information on the usefulness of the technique and operating principles.The DSC
18、 measures heat flow to and from a sample as a function of temperature. As a result, it can measure thermal energy generated by the reaction of electrode with electrolyte. 9.2.1 Samples without Electrolytex Non-hermetic Al pan x Prepare samples per equipment instructions9.2.2 Samples with Electrolyte
19、x A hermetically sealed pan should be used to prevent reaction of electrolyte with air (particularly water). Pan will open when gaseous components cause sufficient increase in pressure temperature data beyond this point is no longer meaningful. Hermetic pans can open energetically, as a result users
20、 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 an enclosure. x Samples should be prepared in an inert environment. Test parameters: x Initial sample size:
21、10 to 50 mg (follow instructions for particular instrument)x Temperature range: 25 to 400 Cx Temperature ramp: 1 C/minSAE INTERNATIONAL J3021 Issued OCT2014 Page 5 of 79.3 Accelerating Rate Calorimetry (ARC)ASTM E1981-98 (Standard guide for assessing the thermal stability of materials by methods of
22、accelerating rate calorimetry) provides general information on the usefulness of the technique and operating principles.ARC is 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 me
23、asured. ARC data can generally be correlated to DSC data. ARC samples use more material than DSC samples. ARC samples allow the use of significant amounts of excess electrolyte which influence the test results. Users interested in measuring the heat flow from a material are encouraged to first inves
24、tigate using DSC. If ARC is pursued, users should define an appropriate amount of electrolyte to be used. The comments made at the beginning of section 8 regarding changes in SOC of the material apply to preparation of samples for ARC. 10. CHEMICAL CONTENT (LI, TRANSITION METAL, RATIO OF LI/TM, IMPU
25、RITIES)Inductively coupled plasma atomic emission spectroscopy, also referred to as inductively coupled plasma optical emission spectrometry (ICP-OES) is recommended for quantification of the elemental content, except carbon and sulfur, of the materials. ICP methods are not recommended for C and S q
26、uantification because these may not be discernible from the inherent background levels. For quantification of the carbon or sulfur content, a combustion / evolved gas analyzer for carbon and sulfur content could be used. Combustion techniques will measure organic carbon content. Users wanting to qua
27、ntify elemental content down to the parts per billion level are advised to use ICP-mass spectrometry (ICP-MS). In all cases, ICP-OES, ICP-MS and combustion/evolved gas, measurement is to be performed per instrument guidelines.11. WATER CONTENTCoulometric Karl Fisher titration method is recommended f
28、or water content determination, particularly for materials with water content 100nm. TEM analysis is necessary to visualize morphology of particles with length scales of 100nm. TEM is also necessary to look at surface morphology, for example the detection of surface treatment layers. NOTE: microscop
29、y techniques are more commonly used in R&D. In production, typically surface area and particle size analysis are used to confirm material conformance with specified requirementsIn all cases, users should follow instrument guidelines for mounting and analysis of the sample. 14. OHMIC PROPERTIESThe in
30、trinsic ohmic properties (electrical conductivity and resistivity) of the material should be measured in a single crystal. However, single crystal growth is outside of the scope of this documentMeasurement of ohmic properties for a powder sample is dependent on particle surface area and packing of t
31、he particle to form the sample (for example, a pressed pellet). Also, the performance of the cathode in a battery is not strictly determined by the ohmic properties of the active material since most battery positive electrodes have high surface area carbon additive for electron conductivity. For the
32、se reasons, techniques to measure ohmic properties of the powder will not be included in this document. The user is advised to measure ohmic properties of an electrode optimized for the intended application.15. NOTES15.1 Marginal IndiciaA change bar (l) located in the left margin is for the convenie
33、nce of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only.PREPARED BY THE BATTERY MATERIALS TESTING COMMITTEE
