CN112993376B - Matching method of lithium ion battery cells - Google Patents
Matching method of lithium ion battery cells Download PDFInfo
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- CN112993376B CN112993376B CN202110191642.4A CN202110191642A CN112993376B CN 112993376 B CN112993376 B CN 112993376B CN 202110191642 A CN202110191642 A CN 202110191642A CN 112993376 B CN112993376 B CN 112993376B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/04—Construction or manufacture in general
- H01M10/0404—Machines for assembling batteries
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
- B07C5/34—Sorting according to other particular properties
- B07C5/344—Sorting according to other particular properties according to electric or electromagnetic properties
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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Abstract
The invention provides a matching method of lithium ion battery cells, which comprises the following steps: rejecting abnormal points of the battery cell capacity, the alternating current internal resistance and the self-discharge parameters; fully charging and then fully discharging the battery cell, calculating the differential pressure of a charging and discharging platform, and grading the battery cell according to the differential pressure of the charging and discharging platform; then, calculating the capacity of a discharging platform of the battery cell from 60% SOC to 40% SOC, and performing secondary grouping according to the capacity of the discharging platform; and automatically grouping the cells in the same group in series-parallel connection. The invention considers the dynamic balance of lithium ion deintercalation and the consistency of a discharge platform in the actual charging and discharging process of the battery cell, remarkably improves the whole capacity exertion of the battery cell package compared with a method for grouping according to the capacity, improves the original capacity conversion rate of 85-92 percent to 94-97 percent, reduces the module heat production, reduces the internal consumption and has simple and easy operation.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a matching method of lithium ion battery cells.
Background
The lithium ion battery as an environment-friendly battery has the advantages of high energy density, high working voltage, high safety performance, long service life and the like.
At present, the commonly used matching scheme in the lithium battery industry is basically to group by capacity, and scattered points are only removed from parameters such as liquid retention capacity, internal resistance, self-discharge and shipment voltage of a battery cell. The matching scheme only considers the static state of the battery cell and ignores the dynamic change of the battery cell in the working process. Therefore, the capacity of the lithium ion battery cells after being assembled is reduced compared with the capacity of the single battery cells, the phenomenon of insufficient driving mileage of a vehicle is directly caused, and the production cost of the single battery cells is increased.
Disclosure of Invention
In order to solve the technical problems, the invention provides a matching method of lithium ion battery cells, which comprises the steps of obtaining a full-discharge charge-discharge curve through a charge-discharge test, differentiating the curve to obtain a median platform voltage, classifying the cells according to the charge-discharge median platform voltage difference, calculating the discharge platform capacity of the cells, and performing secondary grouping according to the discharge platform capacity. The median platform pressure difference reflects the dynamic balance of lithium ion deintercalation of the battery cell in the charging and discharging process, and the battery cells with consistent lithium ion deintercalation performance are matched and assembled, so that the capacity exertion of the module is facilitated. The consistency of the battery cores can be further guaranteed by grouping the capacities of the discharge platforms again, so that the capacity conversion rate is improved.
The technical scheme adopted by the invention is as follows:
a matching method of lithium ion battery cells comprises the following steps:
(1) rejecting abnormal points of the battery cell capacity, the alternating current internal resistance and the self-discharge parameters;
(2) fully charging and then fully discharging the battery cell, calculating the differential pressure of a charging and discharging platform, and grading the battery cell according to the differential pressure of the charging and discharging platform; the charge-discharge platform voltage difference is the charge platform voltage-discharge platform voltage, and the charge-discharge platform voltage is the charge-discharge voltage (also called the median voltage) corresponding to 50% SOC;
(3) then, calculating the capacity of a discharging platform of the battery cell from 60% SOC to 40% SOC, and performing secondary grouping according to the capacity of the discharging platform;
(4) and automatically grouping the cells in the same group by series-parallel connection.
Further, in the step (1), the battery cells with the reserved capacity, the alternating current internal resistance and the self-discharge respectively outside the reserved capacity mean value +/-3 sigma, outside the alternating current internal resistance mean value +/-3 sigma and outside the self-discharge mean value +/-3 sigma are removed.
And (2) grading the charge and discharge platform pressure difference of all the cells from low to high at intervals of 2-50% of the average value of the charge and discharge platform pressure difference, preferably at intervals of 30-50 mV.
In the step (3), the capacities of the discharge platforms of all the battery cells are grouped from low to high at intervals of 1-10% of the average value of the capacities of the charge and discharge platforms, and preferably at intervals of 1.5-2.0 Ah.
And (4) randomly selecting the cells from the cells in the same group to form a unit module.
The lithium ion battery obtained by the matching of the matching method provided by the invention improves the whole capacity exertion of the battery cores after being grouped.
Compared with the prior art, the dynamic balance of lithium ion deintercalation and the consistency of a discharge platform in the actual charging and discharging process of the battery cell are considered, and compared with a method for grouping according to capacity, the method obviously improves the whole capacity exertion of the battery cell package, improves the original capacity conversion rate of 85-92% to 94-97%, reduces the heat production of modules and reduces the internal consumption. The operation is simple and easy.
Drawings
Fig. 1 is a flowchart of a lithium ion battery cell grouping method according to the present invention;
FIG. 2 is a temperature change curve during discharge of lithium ion cells obtained by the grouping method in example 1 and comparative example 1;
fig. 3 is a temperature change curve during discharge of the lithium ion cells obtained by the grouping method in example 2 and comparative example 2.
Detailed Description
The conditions of the charge and discharge test and the capacity conversion rate in each of the examples and comparative examples were calculated as follows:
charging and discharging test conditions: 1. charging the module to the upper limit voltage of the module (the upper limit of the voltage of the single battery cell is connected in series) by a constant current of 1C; 2. charging at an upper limit voltage until the current is reduced to 0.05C; 3. standing for 5 min; 4. discharging the module to a module lower limit voltage (lower limit of single cell voltage) by using a 1C current constant current, wherein the capacity value obtained in the step is the capacity value of the module; 5. standing for 5 min;
the capacity conversion rate is the module capacity/the minimum single-cell capacity (the minimum capacity value in each single cell constituting the module);
remarking: the upper and lower voltage limits of the single battery cell are determined by the main materials of the battery cell with positive and negative poles, and the upper and lower voltage limits of lithium iron phosphate in the example are as follows: 3.65V, 2.5V; the upper and lower limit voltages of the nickel cobalt lithium manganate are as follows: 4.2V, 2.8V;
the temperature rise curves in the discharge process in each example and comparative example were obtained in the following manner:
and (4) monitoring the large-area temperature of the battery cell by using a multi-path temperature measuring instrument while performing the charging and discharging, and intercepting the temperature change corresponding to the step 4 to make a temperature rise curve.
Example 1[ lithium iron phosphate-energy storage crust ]
A matching method of 100Ah lithium iron phosphate energy storage hard shell battery cells comprises the following steps:
(1) rejecting abnormal points of parameters such as cell holding capacity, alternating current internal resistance and self-discharge, and selecting cells with performance parameters meeting the following standards: the battery cell with the capacity of 500 +/-3 g, the alternating current internal resistance of 0.2-0.3 m omega and the self-discharge of-0.2 mV/h is characterized in that the capacity, the alternating current internal resistance and the self-discharge are all within the capacity mean value +/-3 sigma, the alternating current internal resistance mean value +/-3 sigma and the self-discharge mean value +/-3 sigma;
(2) and (3) carrying out charge and discharge tests on the battery cell: charging to 3.65V at constant current and constant voltage of 1.50A, and discharging to 2.5V at constant current of 50A; calculating the differential pressure of a charge and discharge platform, wherein the differential pressure of the charge and discharge platform is the charge platform voltage-discharge platform voltage, the charge and discharge platform voltage is the charge and discharge voltage (also called the median voltage) corresponding to 50% of SOC, and the charge and discharge platform voltage is primarily classified into grades 1, 2 and 3 by using the platform differential pressure at 50 mV;
(3) then, calculating the platform capacity of the battery cell from 60% SOC to 40% SOC, wherein the platform capacity is the capacity value corresponding to 60% SOC-the capacity value corresponding to 40% SOC, arranging the discharge platform capacities of all the battery cells from low to high, and performing secondary grouping at intervals of 2 Ah;
(4) and randomly selecting the battery cells from the battery cells of the same group to form a unit module.
The average value of the capacity conversion rate of the 3 2-string minimum unit modules prepared from 6 battery cells in the embodiment is calculated by performing charge and discharge tests, and is increased by 6.9% compared with that of the comparative example 1.
Example 2[ lithium nickel cobalt manganese oxide-Power hard Shell ]
Selecting 50Ah nickel cobalt lithium manganate battery core hard shell battery cores, grouping the battery cores through a conventional grouping scheme, selecting the battery cores from the same group of battery cores to form a module, and performing charge-discharge test to calculate the capacity conversion rate of the battery cores.
The specific grouping scheme is as follows:
(1) rejecting abnormal points of parameters such as cell holding capacity, alternating current internal resistance and self-discharge: keeping the quantity of the cells within 150 +/-3 g, the alternating current internal resistance of 0.5-0.7 m omega and the self-discharge of-0.1-0.15 mV/h, namely keeping the quantity, the alternating current internal resistance and the self-discharge within +/-3 sigma of the mean value of the quantity, +/-3 sigma of the alternating current internal resistance and +/-3 sigma of the mean value of the self-discharge;
(2) and (3) carrying out charge and discharge tests on the battery cell: charging to 4.2V at constant current and constant voltage of 1.25A, and then discharging to 2.8V at constant current of 25A; calculating the differential pressure of the charging and discharging platform, classifying the differential pressure of the charging and discharging platform of all the electric cores from low to high at intervals of 30mV, and primarily classifying the differential pressure into grades 1, 2 and 3;
(3) then calculating the platform capacity of the battery cells from 60% SOC to 40% SOC, arranging the discharge platform capacities of all the battery cells from low to high, and performing secondary grouping at intervals of 1.5 Ah;
(4) and randomly selecting the battery cells from the battery cells of the same group to form a unit module.
The average value of the capacity conversion rate of the 3 2-string minimum unit modules prepared from 6 battery cells in the embodiment is calculated by performing charge and discharge tests, and is increased by 6.6% compared with that of the comparative example 1.
Comparative example 1[ lithium iron phosphate-energy storage crust ]
A matching method of 100Ah lithium iron phosphate energy storage hard shell battery cells comprises the following steps:
(1) selecting the battery cell with the performance parameter meeting the following standard: the battery cell with the capacity of 500 +/-3 g, the alternating current internal resistance of 0.2-0.3 m omega and the self-discharge of-0.2 mV/h is characterized in that the capacity, the alternating current internal resistance and the self-discharge are all within the capacity mean value +/-3 sigma, the alternating current internal resistance mean value +/-3 sigma and the self-discharge mean value +/-3 sigma;
(2) grading the capacity: the capacity mean value-3 sigma is used as a lower limit of classification, the capacity mean value +3 sigma is used as an upper limit of classification, the capacity mean value-3 sigma + m 2Ah is automatically classified, m is a grade, and m is 1, 2 and 3 … ….
(3) And randomly selecting the battery cells from the battery cells at the same level to form a unit module.
The average value of the capacity conversion rate was calculated by performing a charge-discharge test on 3 2-string minimum unit modules composed of 6 cells in this comparative example, and the result is shown in table 1.
Comparative example 2[ lithium nickel cobalt manganese oxide-Power hard Shell ]
A matching method of 50Ah nickel cobalt lithium manganate power hard shell battery cores comprises the following steps:
(1) selecting the battery cell with the performance parameter meeting the following standard: keeping the cell capacity of 150 +/-3 g, the alternating current internal resistance of 0.5-0.7 m omega and the self-discharge of-0.1-0.15 mV/h, namely keeping the cell capacity, the alternating current internal resistance and the self-discharge within the average value +/-3 sigma of the keeping capacity, the average value +/-3 sigma of the alternating current internal resistance and the average value +/-3 sigma of the self-discharge;
(2) grading the capacity: the capacity mean value-3 sigma is used as a lower limit of classification, the capacity mean value +3 sigma is used as an upper limit of classification, the capacity mean value-3 sigma + m 1.5Ah is automatically classified, m is a grade, and m is 1, 2 and 3 … ….
(3) And randomly selecting the battery cells from the battery cells at the same level to form a unit module.
The average value of the capacity conversion rate was calculated by performing a charge and discharge test on 3 2-string minimum unit modules composed of 6 cells in this comparative example, and the result is shown in table 1.
TABLE 1
The temperature change curves of the minimum cell module discharge processes in the examples and comparative examples were tested, and the results are shown in fig. 2 and 3, from which it can be seen that the temperature rise of 3 samples in examples 1 and 2 is significantly lower than that of 3 samples in comparative examples 1 and 2.
The above detailed description of a method for assembling lithium ion battery cells with reference to the embodiments is illustrative and not restrictive, and several embodiments may be enumerated within the scope of the limitations, so that changes and modifications may be made without departing from the spirit of the present invention.
Claims (6)
1. A matching method of lithium ion battery cells is characterized by comprising the following steps:
(1) removing cells with abnormal retention capacity, alternating current internal resistance and self-discharge parameters;
(2) fully charging and then fully discharging the battery cell, calculating the differential pressure of a charging and discharging platform, and grading the battery cell according to the differential pressure of the charging and discharging platform;
(3) then, calculating the capacity of a discharging platform of the battery cell from 60% SOC to 40% SOC, and performing secondary grouping according to the capacity of the discharging platform;
(4) automatically grouping the cells in the same group in series-parallel connection;
and (2) grading the charge and discharge platform pressure differences of all the battery cells from low to high at intervals of 30-50 mV.
2. The grouping method of lithium ion battery cells according to claim 1, wherein in step (3), the capacities of the discharge platforms of all the cells are grouped from low to high every 1-10% by the average value of the capacities of the charge and discharge platforms.
3. The matching method of the lithium ion battery cells of claim 2, wherein the grouping is performed every 1.5-2.0 Ah.
4. The grouping method for lithium ion battery cells according to any of claims 1 to 3, wherein in step (4), the cells in the same group are randomly selected to form a unit module.
5. The grouping method for lithium ion battery cells according to any of claims 1 to 3, wherein in step (1), cells with retention capacity, internal ac resistance and self-discharge respectively outside the retention capacity mean ± 3 sigma, the internal ac resistance mean ± 3 sigma and the self-discharge mean ± 3 sigma are rejected.
6. A lithium ion battery assembled by the assembly method of any one of claims 1 to 3.
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| CN104332665A (en) * | 2014-08-21 | 2015-02-04 | 中航锂电（洛阳）有限公司 | Battery grouping method |
| CN104617339A (en) * | 2014-11-18 | 2015-05-13 | 中国南方电网有限责任公司调峰调频发电公司 | Lithium ion battery group matching method |
| CN112103577A (en) * | 2020-09-25 | 2020-12-18 | 江苏双登富朗特新能源有限公司 | Lithium ion battery grouping method |
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| CN102800901B (en) * | 2012-08-21 | 2017-07-18 | 唐世宏 | Li-ion batteries piles cell classification method for group matching |
| CN104319421B (en) * | 2014-09-28 | 2017-02-08 | 东莞市能优能源科技有限公司 | lithium ion battery matching system |
| CN105489952A (en) * | 2016-01-08 | 2016-04-13 | 深圳市沃特玛电池有限公司 | Matching method for improving self-discharge consistency of lithium iron phosphate power battery pack |
| CN107589375B (en) * | 2017-08-02 | 2020-04-14 | 合肥国轩高科动力能源有限公司 | Ternary battery cell grouping performance optimization method and system based on secondary voltage sorting |
| CN108246658B (en) * | 2017-12-12 | 2020-03-20 | 合肥国轩高科动力能源有限公司 | Method for screening consistency of lithium iron phosphate batteries |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104332665A (en) * | 2014-08-21 | 2015-02-04 | 中航锂电（洛阳）有限公司 | Battery grouping method |
| CN104617339A (en) * | 2014-11-18 | 2015-05-13 | 中国南方电网有限责任公司调峰调频发电公司 | Lithium ion battery group matching method |
| CN112103577A (en) * | 2020-09-25 | 2020-12-18 | 江苏双登富朗特新能源有限公司 | Lithium ion battery grouping method |
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