CN111766173A - Method for evaluating coke quality for lithium battery negative electrode material - Google Patents
Method for evaluating coke quality for lithium battery negative electrode material Download PDFInfo
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- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
- G01N5/04—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by removing a component, e.g. by evaporation, and weighing the remainder
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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Abstract
The invention relates to a method for evaluating the quality of coke for a lithium battery negative electrode material, which comprises the following steps: s1, airing the raw coke sample, coarsely breaking, and fully sieving by 4mm to obtain primary coke powder; s2, carrying out heat treatment on the primary coke powder at 700-800 ℃ in a nitrogen atmosphere, and then crushing the primary coke powder to be completely sieved by 0.071mm to obtain secondary coke powder; and S3, drying the secondary coke powder at 110-140 ℃ in vacuum, heating the secondary coke powder from 50 ℃ to 900 ℃ at the speed of 2-5 ℃/min in an air atmosphere, and carrying out thermogravimetric detection to determine the reaction starting temperature of the change of the graphitization degree and the reaction starting temperature of the reversible capacity change. Compared with the prior art, the invention has the beneficial effects that: the method can quickly distinguish the quality grade of the green coke for the negative electrode, has small sample amount and quick and sensitive analysis; strong operability, large elasticity of testing conditions and the like, and the early-stage sample preparation is simpler, more convenient and more time-saving than the traditional sample preparation.
Description
Technical Field
The invention relates to the technical field of carbon materials, relates to a method for quickly evaluating the quality of coke for a lithium battery negative electrode material, and particularly relates to a method for quickly evaluating the graphitization easiness of negative electrode coke and quickly estimating the reversible capacity of the negative electrode coke.
Background
Currently, lithium batteries have been widely used in various fields such as digital, energy storage, and power, due to their characteristics of high energy density, good cycle performance, rate capability, no memory, and no pollution. The negative electrode material of the lithium ion battery comprises natural graphite, artificial graphite (needle coke, pitch coke, petroleum coke, same-polarity coke, intermediate-phase carbon microspheres and the like) and alloy materials, wherein the artificial graphite has attracted more and more attention by battery manufacturers due to the advantages of good compatibility with electrolyte, good cycle performance and the like.
At present, the evaluation means of the quality of the coke for the negative electrode is a big blank in China, most suppliers continue the evaluation indexes of the traditional carbon material, such as CTE, true density, volatile components, ash content, N, S content and the like, and the indexes have poor pertinence to lithium battery negative electrode manufacturers and almost have no guiding significance. Generally, negative electrode material manufacturers need to obtain the reversible capacity and the first coulombic efficiency of the material after the raw materials are subjected to early-stage drying, crushing, grading and graphitization and assembled into a button-type half cell and a charge-discharge test, and finally evaluate the quality grade of the coke raw material according to the two contents.
Although the chinese patent CN 107764681 a, a method for rapidly evaluating coke raw material, avoids the defect that the quality of a half cell can be evaluated only after assembling coke for a negative electrode into the half cell in a large direction, and the detection time is greatly shortened, the sample preparation in the early stage is too tedious, and has certain requirements on the sample amount, and the sample preparation parallelism and other human errors are introduced, which finally results in the real situation that the evaluation result is out of focus.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to develop a set of method for rapidly judging the quality grade of the coke for the negative electrode material in the lithium battery industry, and the method can be used for rapidly evaluating the graphitization performance of the coke for the negative electrode and estimating the reversible capacity of the coke.
The invention is realized by the following technical scheme:
the invention provides a method for evaluating the quality of coke for a lithium battery negative electrode material, which comprises the following steps:
s1, airing the raw coke sample, coarsely breaking, and fully sieving by 4mm to obtain primary coke powder;
s2, carrying out heat treatment on the primary coke powder at 700-800 ℃ in a nitrogen atmosphere, and then crushing the primary coke powder to be completely sieved by 0.071mm to obtain secondary coke powder;
and S3, drying the secondary coke powder at 110-140 ℃ in vacuum, heating the secondary coke powder from 50 ℃ to 900 ℃ at the speed of 2-5 ℃/min in an air atmosphere, and carrying out thermogravimetric detection to determine the reaction starting temperature of the change of the graphitization degree and the reaction starting temperature of the reversible capacity change.
Preferably, the rough crushing in step S1 is performed by using a jaw crusher.
Preferably, the pulverization in step S2 is carried out by a shear pulverizer.
Preferably, the flow rate of the air atmosphere in step S3 is 40 to 80 ml/min.
Preferably, the method for determining the reaction start temperature in step S3 is: and the intersection point temperature of the baseline extension line and the tangent of the maximum weight loss point on the thermal weight loss curve of the green coke. As shown in fig. 1.
Compared with the prior art, the invention has the beneficial effects that:
1. the method can quickly distinguish the quality grade of the green coke for the negative electrode, and compared with the traditional method for 7-10 days, the method only needs 1.5-3 hours;
2. the method has the characteristics of small sample amount and rapid and sensitive analysis, and the measurement error is +/-2 ℃;
3. the operability is strong, the testing condition has great elasticity, and the sample loading quantity, the heating rate and the air input do not influence the analysis result.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a thermogravimetric plot of green coke in the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
Example 1
Sampling needle coke green coke by 50-100 g, spreading the needle coke green coke in a thin layer in an iron disc, naturally drying the needle coke green coke, coarsely crushing the needle coke by using a jaw crusher, and fully sieving the needle coke by 4mm to obtain primary coke powder;
putting the primary coke powder sample into an alumina crucible, carrying out heat treatment for 20-60 min at 700-800 ℃ in a nitrogen atmosphere, and then crushing the sample by using a shearing crusher to obtain secondary coke powder, wherein the secondary coke powder is sieved by 0.071 mm;
dividing the secondary coke powder into two batches, and testing the thermogravimetry of one batch by self; and the other batch is sent to a battery manufacturer according to the traditional method for charge-discharge detection and graphitization degree test:
the specific method for self-testing the thermogravimetry is as follows:
uniformly weighing the secondary coke powder with no less than or equal to 5mg, placing the secondary coke powder in a 70ml alumina crucible, heating the secondary coke powder from 50 ℃ to 900 ℃ at the speed of 2-5 ℃/min in an air atmosphere with the flow rate of 40-80 ml/min to perform thermogravimetric detection, and determining the reaction starting temperature of the change of the graphitization degree and the reaction starting temperature of the reversible capacity change, wherein the judgment method of the reaction starting temperature comprises the following steps: and the intersection point temperature of the baseline extension line and the tangent line of the maximum weight loss point.
The test results are:
and (3) thermogravimetry: the air input is 40ml/min, the temperature is increased from 50 ℃ to 900 ℃ at the speed of 5 ℃/min, and the initial reaction temperature is 570 ℃;
the manufacturer: degree of graphitization 96.7%, gram capacity: 325 mAh/g.
Example 2
Sampling 50-100 g of raw asphalt coke, spreading the raw asphalt coke in a thin layer in an iron pan, naturally drying the raw asphalt coke, coarsely crushing the raw asphalt coke by using a jaw crusher, and fully sieving the raw asphalt coke by 4mm to obtain primary coke powder;
putting the primary coke powder sample into an alumina crucible, carrying out heat treatment for 20-60 min at 700-800 ℃ in a nitrogen atmosphere, and then crushing the sample by using a shearing crusher to obtain secondary coke powder, wherein the secondary coke powder is sieved by 0.071 mm;
dividing the secondary coke powder into two batches, and testing the thermogravimetry of one batch by self; and the other batch is sent to a battery manufacturer according to the traditional method for charge-discharge detection and graphitization degree test:
the specific method for self-testing the thermogravimetry is as follows:
uniformly weighing the secondary coke powder with no less than or equal to 5mg, placing the secondary coke powder in a 70ml alumina crucible, heating the secondary coke powder from 50 ℃ to 900 ℃ at the speed of 2-5 ℃/min in an air atmosphere with the flow rate of 40-80 ml/min to perform thermogravimetric detection, and determining the reaction starting temperature of the change of the graphitization degree and the reaction starting temperature of the reversible capacity change, wherein the judgment method of the reaction starting temperature comprises the following steps: and the intersection point temperature of the baseline extension line and the tangent line of the maximum weight loss point.
The test results are:
and (3) thermogravimetry: the air input is 50ml/min, the temperature is increased from 50 ℃ to 900 ℃ at the speed of 2.5 ℃/min, and the initial reaction temperature is 555 ℃;
the manufacturer: degree of graphitization 94.5%, gram capacity: 319 mAh/g.
Example 3
Sampling 50-100 g of the same-quality coke green coke, spreading the same-quality coke green coke in a thin layer in an iron disc, naturally drying the same-quality coke green coke, coarsely crushing the same-quality coke by using a jaw crusher, and fully sieving the same-quality coke green coke by 4mm to obtain primary coke powder;
putting the primary coke powder sample into an alumina crucible, carrying out heat treatment for 20-60 min at 700-800 ℃ in a nitrogen atmosphere, and then crushing the sample by using a shearing crusher to obtain secondary coke powder, wherein the secondary coke powder is sieved by 0.071 mm;
dividing the secondary coke powder into two batches, and testing the thermogravimetry of one batch by self; and the other batch is sent to a battery manufacturer according to the traditional method for charge-discharge detection and graphitization degree test:
the specific method for self-testing the thermogravimetry is as follows:
uniformly weighing the secondary coke powder with no less than or equal to 5mg, placing the secondary coke powder in a 70ml alumina crucible, heating the secondary coke powder from 50 ℃ to 900 ℃ at the speed of 2-5 ℃/min in an air atmosphere with the flow rate of 40-80 ml/min to perform thermogravimetric detection, and determining the reaction starting temperature of the change of the graphitization degree and the reaction starting temperature of the reversible capacity change, wherein the judgment method of the reaction starting temperature comprises the following steps: and the intersection point temperature of the baseline extension line and the tangent line of the maximum weight loss point.
The test results are:
and (3) thermogravimetry: the air input is 65ml/min, the temperature is increased from 50 ℃ to 900 ℃ at the speed of 4 ℃/min, and the initial reaction temperature is 530 ℃;
the manufacturer: degree of graphitization 85.2%, gram capacity: 290 mAh/g.
Example 4
Sampling 50-100 g of a fir technical negative electrode material SPT-6t, spreading the sampled material in a thin layer in an iron disc, naturally airing, roughly crushing by using a jaw crusher, and fully sieving by 4mm to obtain primary coke powder;
putting the primary coke powder sample into an alumina crucible, carrying out heat treatment for 20-60 min at 700-800 ℃ in a nitrogen atmosphere, and then crushing the sample by using a shearing crusher to obtain secondary coke powder, wherein the secondary coke powder is sieved by 0.071 mm;
dividing the secondary coke powder into two batches, and testing the thermogravimetry of one batch by self; and the other batch is sent to a battery manufacturer according to the traditional method for charge-discharge detection and graphitization degree test:
the specific method for self-testing the thermogravimetry is as follows:
uniformly weighing the secondary coke powder with no less than or equal to 5mg, placing the secondary coke powder in a 70ml alumina crucible, heating the secondary coke powder from 50 ℃ to 900 ℃ at the speed of 2-5 ℃/min in an air atmosphere with the flow rate of 40-80 ml/min to perform thermogravimetric detection, and determining the reaction starting temperature of the change of the graphitization degree and the reaction starting temperature of the reversible capacity change, wherein the judgment method of the reaction starting temperature comprises the following steps: and the intersection point temperature of the baseline extension line and the tangent line of the maximum weight loss point.
The test results are:
and (3) thermogravimetry: the air input is 45ml/min, the temperature is increased from 50 ℃ to 900 ℃ at the speed of 5 ℃/min, and the initial reaction temperature is 570 ℃;
the manufacturer: degree of graphitization 98.1%, gram capacity: 345 mAh/g.
The graphitization degree and reversible capacity of the green coke measured in examples 1 to 4 are shown in Table 1.
TABLE 1
| onset(℃) | Degree of graphitization G (%) | Reversible capacity (mAh/g) |
| <510 | 78-85 | 180-220 |
| 510-540 | 85-90 | 220-300 |
| 540-560 | 90-95 | 300-320 |
| >560 | >95 | 300-320 |
In summary, the present invention is only a preferred embodiment, and not intended to limit the scope of the invention, and all equivalent changes and modifications in the shape, structure, characteristics and spirit of the present invention described in the claims should be included in the scope of the present invention.
Claims (5)
1. A method for evaluating the quality of coke for a negative electrode material of a lithium battery is characterized by comprising the following steps of:
s1, airing the raw coke sample, coarsely breaking, and fully sieving by 4mm to obtain primary coke powder;
s2, carrying out heat treatment on the primary coke powder at 700-800 ℃ in a nitrogen atmosphere, and then crushing the primary coke powder to be completely sieved by 0.071mm to obtain secondary coke powder;
and S3, drying the secondary coke powder at 110-140 ℃ in vacuum, heating the secondary coke powder from 50 ℃ to 900 ℃ at the speed of 2-5 ℃/min in an air atmosphere, and carrying out thermogravimetric detection to determine the reaction starting temperature of the change of the graphitization degree and the reaction starting temperature of the reversible capacity change.
2. The method for evaluating the quality of coke for a negative electrode material of a lithium battery as claimed in claim 1, wherein the rough crushing in step S1 is performed using a jaw crusher.
3. The method for evaluating the quality of coke for a negative electrode material of a lithium battery as claimed in claim 1, wherein the pulverization in the step S2 is carried out by using a shear pulverizer.
4. The method for evaluating the coke quality for a negative electrode material of a lithium battery as claimed in claim 1, wherein the flow rate of the air atmosphere in step S3 is 40 to 80 ml/min.
5. The method of evaluating the coke quality for a negative electrode material of a lithium battery as claimed in claim 1, wherein the determination of the reaction initiation temperature in step S3 is performed by: and the intersection point temperature of the extension line of the base line on the thermal weight loss curve of the coke powder and the tangent line of the maximum weight loss point.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117935995A (en) * | 2024-03-21 | 2024-04-26 | 江苏众钠能源科技有限公司 | Hard carbon material screening method and device for ion battery |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103323490A (en) * | 2013-06-26 | 2013-09-25 | 武汉钢铁(集团)公司 | Device and method for detecting solution loss initial temperature and solution loss speed of coke |
| CN107764681A (en) * | 2017-10-16 | 2018-03-06 | 深圳市贝特瑞新能源材料股份有限公司 | A kind of fast appraisement method of burnt raw material |
| CN108519301A (en) * | 2018-03-12 | 2018-09-11 | 沈阳环境科学研究院 | It is a kind of to utilize thermogravimetric analyzer evaluation coal and the reactive method of biomass char |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103323490A (en) * | 2013-06-26 | 2013-09-25 | 武汉钢铁(集团)公司 | Device and method for detecting solution loss initial temperature and solution loss speed of coke |
| CN107764681A (en) * | 2017-10-16 | 2018-03-06 | 深圳市贝特瑞新能源材料股份有限公司 | A kind of fast appraisement method of burnt raw material |
| CN108519301A (en) * | 2018-03-12 | 2018-09-11 | 沈阳环境科学研究院 | It is a kind of to utilize thermogravimetric analyzer evaluation coal and the reactive method of biomass char |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117935995A (en) * | 2024-03-21 | 2024-04-26 | 江苏众钠能源科技有限公司 | Hard carbon material screening method and device for ion battery |
| CN117935995B (en) * | 2024-03-21 | 2024-06-11 | 江苏众钠能源科技有限公司 | Hard carbon material screening method and device for ion battery |
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Address after: Weisan Road Chemical Office Building, Baoshan District, Shanghai, 2004 Applicant after: Baowu Carbon Technology Co.,Ltd. Address before: Weisan Road Chemical Office Building, Baoshan District, Shanghai, 2004 Applicant before: BAOWU CARBON MATERIAL TECHNOLOGY Co.,Ltd. |
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Application publication date: 20201013 |