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GB/T 38823-2020 English PDF (GBT38823-2020)

GB/T 38823-2020 English PDF (GBT38823-2020)

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GB/T 38823-2020: Silicon-carbon

This Standard specifies the terms and definitions, classification and code, technical requirements, test methods, inspection rules, packaging, marking, transportation, and storage of silicon-carbon. This Standard applies to all kinds of silicon-carbon anode materials for lithium-ion batteries.
GB/T 38823-2020
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 29.050
Q 50
Silicon-carbon
??????
ISSUED ON: JUNE 02, 2020
IMPLEMENTED ON: DECEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 Classification and code ... 5
5 Technical requirements ... 6
5.1 Appearance ... 6
5.2 Physical and chemical indicators ... 6
6 Test methods ... 7
6.1 Appearance ... 7
6.2 Particle size distribution ... 7
6.3 Specific surface area ... 7
6.4 Tap density ... 7
6.5 Carbon content ... 7
6.6 Silicon content ... 7
6.7 Compaction density ... 7
6.8 Moisture content ... 7
6.9 Magnetic impurities ... 7
6.10 Content of trace metal elements ... 7
6.11 Initial discharge specific capacity and initial coulombic efficiency ... 7 6.12 Regulated substances ... 7
7 Inspection rules ... 8
7.1 Sampling method ... 8
7.2 Inspection classification ... 8
7.3 Acceptance rules ... 9
8 Packaging, marking, storage, and transportation ... 9
8.1 Packaging ... 9
8.2 Marking ... 9
8.3 Storage and transportation ... 10
Appendix A (Normative) Determination method of carbon content ... 11
Appendix B (Normative) Determination method of silicon content ... 14
Appendix C (Normative) Determination method for the content of trace metal elements ... 17
Appendix D (Normative) Determination method of initial discharge specific capacity and initial coulombic efficiency ... 20
Silicon-carbon
1 Scope
This Standard specifies the terms and definitions, classification and code, technical requirements, test methods, inspection rules, packaging, marking, transportation, and storage of silicon-carbon.
This Standard applies to all kinds of silicon-carbon anode materials for lithium-ion batteries.
2 Normative references
The following documents are indispensable for the application of this document. For the dated references, only the editions with the dates indicated are applicable to this document. For the undated references, the latest edition (including all the amendments) are applicable to this document.
GB/T 191 Packaging - Pictorial marking for handling of goods
GB/T 2828.1 Sampling procedures for inspection by attributes - Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection GB/T 2829 Sampling procedures and tables for periodic inspection by attributes (apply to inspection of process stability)
GB/T 3782 Acetylene black
GB/T 4369 Lithium
GB/T 5187 Copper and copper alloy foil
GB/T 6388 Transport package shipping mark
GB/T 6682 Water for analytical laboratory use - Specification and test methods GB/T 8170 Rules of rounding off for numerical values and expression and judgement of limiting values
GB/T 13732 General rules for sampling inspection of bulk materials with uniform size
GB/T 19077 Particle size analysis - Laser diffraction methods
GB/T 19587 Determination of the specific surface area of solids by gas adsorption using the BET method
GB/T 21653 Nickel and Nickel-alloy Wire and Drawing Stock
GB/T 24533 Graphite negative electrode materials for lithium ion battery GB/T 26125 Electrical and electronic products - Determination of six regulated substances (lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, polybrominated diphenyl ethers)
GB/T 33827 Determination of magnetic impurities in anode nanomaterials for Li- ion battery
3 Terms and definitions
The following term and definition applies to this document.
3.1
Silicon-carbon
Composite powder material composed of silicon material and carbon material. The synergistic effect of silicon-carbon and cathode materials in a certain system can realize multiple charging and discharging of lithium-ion batteries. During the charging process, the silicon-carbon negative electrode accepts the intercalation of lithium ions. During the discharging process, the lithium ions are extracted.
4 Classification and code
The products are classified according to their initial discharge specific capacity; mainly divided into five categories:
- 400 mAh/g ??? initial discharge specific capacity< 600 mAh/g; represented by SiC-I; - 600 mAh/g ??? initial discharge specific capacity< 900 mAh/g; represented by SiC- ???;
- 900 mAh/g ??? initial discharge specific capacity< 1200 mAh/g; represented by SiC- ???;
- 1200 mAh/g ??? initial discharge specific capacity< 1500 mAh/g; represented by SiC- IV;
- Initial discharge specific capacity???1500 mAh/g; represented by SiC-V. 7 Inspection rules
7.1 Sampling method
7.1.1 Sampling
Silicon-carbon is sampled according to GB/T 13732 ?€?General rules for sampling inspection of bulk materials with uniform size?€?. Insert a clean sampling drill (stainless steel designation 316 or equivalent; diameter: no more than 30 mm) into the package along the axis. The insertion depth must not be less than 4/5 of the package. Take samples within 20 mm around the center axis of the material in the package. Sampling is carried out in accordance with the relevant provisions on sampling in GB/T 2828.1 and GB/T 2829.
7.1.2 Sample label
After the sample is placed in the plastic sample jar, a label shall be attached to the outer wall. The label shall include the following:
a) Sample category and number;
b) Overall material lot number and quantity;
c) Sample size;
d) Sampling date;
e) Name of sampler.
7.1.3 Storage of samples
The samples shall be sealed and stored in an environment protected from bag break, rain and moisture. The effective storage period of spare samples is 12 months. 7.2 Inspection classification
7.2.1 Exit-factory inspection
Inspect the specific surface area, tap density, compaction density, silicon content, magnetic impurities, trace metal elements, 0.1 C initial discharge specific capacity, 0.1 C initial coulombic efficiency, and regulated substance content of each lot. After passing the inspection, stamp the quality inspection seal.
7.2.2 Type inspection
Inspect all technical requirements specified in this Standard. Type inspection is carried out in one of the following situations:
a) When the model and supplier of raw materials are changed;
b) When there is a change in the production technology process;
c) When the production equipment has been shut down for more than half a year and starts production again;
d) When customers have special requirements;
e) Under normal circumstances, the type inspection shall be conducted at least once a year.
7.3 Acceptance rules
7.3.1 Products that meet the requirements of technical indicators in Table 1 are conformity products. If there is 1 indicator that fails to meet the requirements of the standard, double number of samples shall be taken from the sampling bag of the same lot of products, to re-inspect the nonconformity item. If all the re-inspections are conformity, it will be judged as conformity. If one item is nonconformity, it will be judged as nonconformity.
7.3.2 The manufacturer shall ensure that, the products that leave the factory meet the requirements of this Standard. When leaving the factory, each lot of products is accompanied with an inspection report.
7.3.3 The re-inspection period of the receiving party is 2 months. If there is any objection, it shall take double number of samples for re-inspection. If there is still a dispute, it will be inspected by a qualified third-party testing agency. 8 Packaging, marking, storage, and transportation
8.1 Packaging
8.1.1 The packaging of the product shall comply with the provisions of GB/T 191. The net weight shall be negotiated by both the supplier and the purchaser.
8.1.2 The packaging shall be carried out in a dry environment. The product shall be first put into a waterproof packaging bag (PE sealing bag and aluminum-plastic sealing bag are recommended). Special packaging requirements are negotiated by both the supplier and the purchaser.
8.1.3 The packaged products are then packaged with outer packaging materials. The packaging materials are negotiated by both the supplier and the purchaser. 8.2 Marking
The marking shall comply with the provisions of GB/T 6388. It shall generally include Appendix A
(Normative)
Determination method of carbon content
A.1 Method summary
Combustion in an oxygen stream converts carbon to carbon monoxide and/or carbon dioxide. Carbon monoxide is catalytically oxidized to carbon dioxide at high temperatures. Use the infrared absorption spectrum of carbon dioxide in the oxygen stream for the measurement.
A.2 Instruments and equipment
A.2.1 High-frequency infrared carbon-sulfur analyzer or carbon determinator. It consists of an infrared source, an independent measuring cell, and a reference cell, etc. A.2.2 Dryer.
A.2.3 Electronic balance: The sensitivity is 0.0001 g.
A.2.4 Porcelain crucible, according to the regulations of the instrument manufacturer, can withstand combustion in a high-frequency induction furnace and does not produce carbon chemicals. The blank value is less than 0.002%. The standard deviation is less than 0.0005%.
Note: Carbon pollutants can usually be removed by burning the crucible in a muffle furnace in the air. The burning time at 1000 ??? is not less than 40 min. The burning time at 1350 ??? is not less than 15 min. Then take out the crucible; put it in a clean heat-resistant plate; cool it for 2 min~3 min; finally store the crucible in a dryer.
A.2.5 Crucible tongs, which can hold the porcelain crucible (see A.2.4). A.3 Analytical procedure
WARNING - The main hazard associated with combustion analysis is the
combustion that occurs when the crucible is burned and during the resulting molten state. Use crucible tongs at all times; store used crucibles in suitable containers. Be careful when opening the oxygen valve. The oxygen during the combustion process shall be purged from the instrument, because high
concentrations of oxygen can easily cause fires in small spaces.
A.3.1 Instrument state confirmation: Prepare for operation according to the manufacturer's instructions; check the gas tightness of the combustion unit and the measuring unit. Before calibrating the instrument and measuring the blank, use samples that can measure carbon and sulfur content (add flux) to test at least 5 times. After the instrument is stable, proceed to the next step.
A.3.2 Instrument calibration: Select certified standard samples to calibrate the instrument according to the method specified in the instrument manual. For samples with a wide range of carbon content distribution, a multi-point method or a linear calibration instrument is recommended.
A.3.3 Weigh the sample: According to the carbon content of the sample, use an electronic balance (see A.2.3) to accurately weigh a certain amount of sample; spread it evenly in a ceramic crucible. And enter the sample name and mass (accurate to 0.0001 g) in the software.
Note: The weighing amount of the sample is related to the carbon content of the selected certified reference material. The absolute carbon content of the sample shall be within the range of the standard curve.
A.3.4 Add flux: Add 1.2 g~1.5 g of multi-component flux (tungsten, tin, iron) into the crucible.
A.3.5 Use crucible tongs to place the crucible described in A.3.4 in the crucible holder. After confirming that the input information is correct, start the test program. A.3.6 After the test is completed, the crucible containing the sample is automatically withdrawn from the furnace. Record the test result in the original record. A.3.7 Hot crucible treatment: After the test is completed, use crucible tongs to put the hot crucible into a uniform container to cool to prevent fire.
A.3.8 Shut down.
A.4 Result calculation and data processing
Read the data automatically displayed by the instrument; take the average of 2 parallel tests. According to the "rounding off" provisions of GB/T 8170, retain 4 significant figures, that is, ????.????%.
A.5 Test report
It shall contain the following content:
a) Sample name, lot number, test date, test instrument model, and operator, etc.; b) Analysis results and presentation methods;
c) Abnormal phenomena observed in the determination;
Appendix B
(Normative)
Determination method of silicon content
B.1 Method summary
In the oxygen or air environment, the silicon-carbon material is fired at a high temperature of 1200 ??C. Carbon in it reacts with oxygen to generate CO2 gas, which is discharged; silicon reacts with oxygen to generate SiO2. Finally all the material is converted into SiO2. According to the mass of the reaction product SiO2, the mass of the silicon element in the original sample can be calculated, to obtain the content of the silicon element in the silicon-carbon material.
B.2 Instruments and equipment
B.2.1 Box-type resistance furnace or atmosphere furnace: It can be used for a long time at a temperature of not less than 1200 ??C.
B.2.2 Corundum crucible: It can be used for a long time at a temperature of not less than 1200 ??C.
B.2.3 Electronic balance: The sensitivity is 0.0001 g.
B.2.4 Medicine spoon.
B.2.5 Crucible tongs.
B.2.6 Blast oven.
B.2.7 Dryer.
B.2.8 Stainless steel tray.
B.3 Analytical procedure
B.3.1 Crucible pretreatment
Before the test, clean and dry the corundum crucible; burn it in a box-type resistance furnace or atmosphere furnace (see B.2.1) at 1200 ??C for 1 h. When the temperature drops below 200 ???, take it out. After a little cooling, put it into a dryer to cool down to room temperature, and weigh. Then burn again, until the mass difference between the two times is not more than 0.3 mg.
B.3.2 Sample weighing
Weigh 1.0000 g~1.2000 g of the sample into the corundum crucible, accurate to 0.1 mg. Weigh 2 pieces and carry out a parallel test.
B.3.3 Test
B.3.3.1 Put the corundum crucibles with the weighed samples into the box-type resistance furnace or atmosphere furnace (see B.2.1) in turn. The corundum crucibles shall not be in contact with each other.
B.3.3.2 Burning program setting of box-type resistance furnace or atmosphere furnace (see B.2.1): The heating rate is not more than 20 ???/min. Rise from room temperature to 1200 ???; burn at 1200 ??? for 8 h; then stop heating.
According to the requirements of the equipment manual or other technical documents, pre-dry the box-type resistance furnace or atmosphere furnace, to prevent the failure of instruments and crucibles such as rupture. During the heating process, if the sample or crucible bursts, splashes or becomes contaminated, the heating program can be readjusted; and the test can be redone.
B.3.3.3 Start the heating program and start burning.
B.3.3.4 Cool and weigh: When the temperature of the box-type resistance furnace or atmosphere furnace (see B.2.1) drops below 200 ??C, open the furnace door; use crucible tongs to take out the crucible; place it in a clean stainless steel tray. Cool for 2 min; place the tray and the sample into a dryer; cool to room temperature. Use an electronic balance (see B.2.3) to weigh the total mass of the cooled crucible and product. B.3.3.5 Constant weight: Put the crucible and product into the box-type resistance furnace or atmosphere furnace (see B.2.1) again. According to the steps of B.3.3.1~B.3.3.4, burn and weigh again. Compare and obtain the mass difference with the first burning. If it does not exceed 0.3 mg, the test is over. Otherwise, repeat this step until the mass difference after two burnings does not exceed 0.3 mg. B.3.4 Result calculation
B.3.4.1 According to the steps of B.3.3, respectively record the crucible mass m0, the sample mass m1, the total mass m2 of crucible and product after burning, and the total mass m3 of crucible and product after the constant weight. Then the silicon content in the sample is calculated according to formula (B.1):
Where:
wSi - The mass fraction of silicon in the sample;
D.4.1 Put the specimen and conductive agent into the oven; bake at 120 ??? for 4 h; then transfer to a drying vessel to cool. Weigh the mixture powder (accurate to 0.0001 g) of 4.55 g of specimen and 0.15 g of conductive agent INTO a small beaker with a capacity of 50 mL; then add 6.0 g of 5% PAA aqueous solution to the beaker. Finally, use a planetary stirrer to prepare a paste (stirring time 15 min; stirring speed 2000 r/min). Note: The reference specimen, the binder, and the conductive agent are weighed in a mass ratio of 91 : 6 : 3.
D.4.2 Apply the paste in D.4.1 evenly on the copper foil; use a 200 ??m film coater to scrape the paste on the copper foil, until the surface is smooth. Then put it into a blast drying oven and bake it at 100 ??C for 2 h. Or use an equivalent type of coating method to obtain a pole piece with a single surface density of 60 g/m2~100 g/m2. D.4.3 The baked pole pieces are cut and pressed into electrodes of various shapes (rectangular strips, strips or circles, etc.). After accurate weighing (accurate to 0.00001 g), put it into a vacuum drying oven; bake it at 120 ??C for 8 h under vacuum conditions, to prepare the silicon-carbon working electrode.
D.4.4 In an argon atmosphere glove box, cut metal lithium into rectangular strips, strips or circles, etc. Then, press the above-mentioned cut metal lithium to the end of the cut strip-shaped nickel mesh (or other current collectors with the same performance), to form a counter electrode (or directly use metal lithium as the counter electrode). D.4.5 ASSEMBLE the positive electrode material electrode and the counter electrode made by the above steps, AND 1 mol/L LiPF6 EC (ethylene carbonate)/DMC (dimethyl carbonate)/EMC (ethyl methyl carbonate) (the volume ratio of EC to DMC to EMD is 1 : 1 : 1) electrolyte (or other electrolytes with equivalent performance), in a glove box to form a well-sealed half-cell conforming to the electrode system.
Note: The specimen pole piece is prepared in a dry room. The temperature is 23 ?????2 ???. The relative humidity is ???35%. The sample cell is prepared in a glove box. The temperature is 23 ?????2 ???. The moisture content is less than or equal to 1 mg/m3. The oxygen content is less than or equal to 1 mg/m3.
D.5 Analytical procedure
Conduct charge-discharge cycle of button cell on cell program-controlled tester. Calculate the average of the data of 4 button cells. The test conditions of the initial discharge specific capacity and the initial coulombic efficiency are as follows: The charge-discharge rate is 0.1 C; the voltage range is 0.005 V~1.5 V.
D.6 Result calculation and data processing
D.6.1 The initial discharge specific capacity and initial coulombic efficiency of the specimen are calculated according to formula (D.1), formula (D.2), and formula (D.3).

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