CN112467240B - High-temperature capacity grading and matching process of lithium ion battery - Google Patents
High-temperature capacity grading and matching process of lithium ion battery Download PDFInfo
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- CN112467240B CN112467240B CN202011518218.8A CN202011518218A CN112467240B CN 112467240 B CN112467240 B CN 112467240B CN 202011518218 A CN202011518218 A CN 202011518218A CN 112467240 B CN112467240 B CN 112467240B
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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
- H01M10/44—Methods for charging or discharging
- H01M10/446—Initial charging measures
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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
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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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
- H01M10/4207—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells for several batteries or cells simultaneously or sequentially
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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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a high-temperature capacity grading and matching process of a lithium ion battery, which specifically comprises the following steps: 1) charging and discharging for the first time: connecting the battery after formation to a charging and discharging cabinet, and carrying out full charging and full discharging for 2-4 times; 2) vibration of the battery: fixedly placing the battery after the first charging and discharging on a vibration table for vibration; 3) capacity grading: connecting the battery after the battery vibration is finished to a charging and discharging cabinet for capacity grading; 4) high-temperature laying aside: transferring the battery into a high-temperature shelving chamber for high-temperature shelving; 5) standing at normal temperature: after the high-temperature shelf is finished, transferring the battery into a room-temperature shelf chamber for room-temperature shelf; 6) measuring voltage and internal resistance: after the laying aside is finished, the voltage V of the battery begins to be measured2Internal resistance R and thickness H, recording and calculating the pressure drop rate; 7) summarizing the recorded data, and carrying out matching delivery according to the matching requirement; the invention can fully consider the consistency of various indexes of the lithium ion battery in the grouping process.
Description
Technical Field
The invention belongs to the technical field of new energy batteries, and particularly relates to a high-temperature capacity grading and matching process of a lithium ion battery.
Background
In recent years, with the increasing scarcity of petroleum resources and the increasing severity of environmental pollution, it is urgent to develop new energy to replace the traditional petrochemical energy, and under this background, it is important to accelerate the development of lithium ion batteries without environmental pollution.
Under the strong support of the nation, the lithium ion battery industry is rapidly developed in recent years, and the manufacturing steps of the battery are slightly different but are basically consistent: stirring, coating, rolling, tabletting, core forming, welding, drying, liquid injection, standing, formation charging, sealing, formation discharging, battery aging, OCV testing, capacity grading, selection and shipment, wherein the lithium ion batteries are generally matched and used in groups when in use.
When the battery module is matched for use, the battery capacity, the internal resistance, the self-discharge, the voltage and the initial state in each group are required to be approximately the same, so that the service life of the battery module can be effectively prolonged when the battery module is used.
The existing battery capacity grading process is carried out by circularly carrying out constant-current constant-voltage charging, shelving and constant-current discharging, is simple in whole and cannot accurately select damaged batteries, and when potential safety hazards exist or the damaged batteries are mistakenly assembled on the battery pack, the overall performance of the battery pack can be influenced by the batteries, so that the using effect is reduced.
Disclosure of Invention
The invention aims to solve the main technical problem of providing a high-temperature capacity grading and matching process of a lithium ion battery, wherein the process uses high-temperature capacity grading to enable the capacity to be more accurate, and a battery vibration process is added to more effectively detect the battery with micro short circuit and large self-discharge, so that the safety of a battery module is further improved.
In order to solve the technical problems, the invention provides the following technical scheme:
a high-temperature capacity grading and matching process of a lithium ion battery specifically comprises the following steps:
1) charging and discharging for the first time: connecting the formed battery to a charging and discharging cabinet, and carrying out full charging and full discharging for 2-4 times, wherein the environmental temperature is controlled to be 25 +/-2 ℃;
2) vibration of the battery: fixedly placing the battery after the first charging and discharging on a vibration table for vibration;
3) capacity grading: connecting the battery after the battery vibration is finished to a charging and discharging cabinet, and performing capacity grading by adopting pressure limiting, current limiting and time limiting, wherein the temperature in the capacity grading stage is controlled to be 42 +/-2 ℃;
4) high-temperature laying aside: transferring the battery into a high-temperature shelving chamber for high-temperature shelving;
5) standing at normal temperature: after the high-temperature shelf is finished, transferring the battery to a room-temperature shelf room for normal-temperature shelf, wherein the shelf time is 96-100 h;
6) measuring voltage and internal resistance: after the laying aside is finished, the voltage V of the battery begins to be measured2Internal resistance R and thickness H, recording, and calculating according to a calculation formula of pressure drop rate: Δ V = (V)1-V2) Calculating a pressure drop rate;
7) recording the capacity M, the internal resistance R, the thickness H, the voltage drop rate delta V and the initial voltage V2And summarizing, and carrying out matching delivery according to the matching requirement.
The following is a further optimization of the above technical solution of the present invention:
the specific operation steps of the first charging and discharging in the step 1) are as follows:
the first stage is as follows: placing the battery on a cabinet for 2-10 min;
and a second stage: starting to discharge by using a constant current of 0.5 ℃ for 150-200min, wherein the voltage limit of the lithium iron phosphate battery is 2.0V, and the voltage limit of the lithium nickel cobalt manganese oxide battery is 2.5V;
and a third stage: laying aside the battery for 2-10 min;
a fourth stage: charging with 0.5C constant current and constant voltage, with the current limit of 0.02C and the time of 180-200min, wherein the voltage limit of the lithium iron phosphate battery is 3.7V, and the voltage limit of the lithium nickel cobalt manganese oxide battery is 4.2V;
the fifth stage: laying aside the battery for 2-10 min;
the sixth stage: discharging with constant current of 0.5 deg.C for 200 min; wherein the voltage limit of the lithium iron phosphate battery is 2.0V, and the voltage limit of the lithium nickel cobalt manganese oxide battery is 2.5V;
a seventh stage: the battery is placed on a charging and discharging cabinet for 2-10 min;
an eighth stage: circularly performing the fourth stage to the seventh stage for 1-3 times;
the ninth stage: and (6) ending.
Further optimization: and (2) after the first charge and discharge in the step 1) is finished, laying aside the battery for 12-14h, measuring the voltage of the battery, and if the voltage of the lithium iron phosphate battery is lower than 2.7V and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.2V, sorting out the battery without circulation.
Further optimization: the vibration direction of the vibration table in the step 2) is single vibration up and down; the vibration frequency is 10-50 Hz; the acceleration is: 25-35m/s2(ii) a The vibration time is as follows: 3-5 h.
Further optimization: and (3) after the battery in the step 2) is vibrated, standing the battery for 2-4h, measuring the voltage of the battery, and if the voltage of the lithium iron phosphate battery is lower than 2.7V and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.2V, sorting out the battery without circulation.
Further optimization: the specific operation steps of the capacity grading in the step 3) are as follows:
the first stage is as follows: the battery is placed on the upper cabinet for 2-10 min;
and a second stage: starting to discharge by using a 0.5C constant current for 150-200min, wherein the voltage limit of the lithium iron phosphate battery is 2.5V, the voltage limit of the lithium nickel cobalt manganese oxide battery is 3.0V, and standing the battery for 2-10min after the constant current discharge is finished;
and a third stage: charging with 0.5C constant current and constant voltage, with the current limit of 0.02C and the time of 180-200min, wherein the voltage limit of the lithium iron phosphate battery is 3.7V, the voltage limit of the lithium nickel cobalt manganese oxide battery is 4.2V, and the battery is placed for 2-10min after the constant current and constant voltage charging is finished;
a fourth stage: discharging with constant current of 0.5 ℃ for 200min, wherein the voltage limit of the lithium iron phosphate battery is 2.5V, the voltage limit of the lithium nickel cobalt manganese oxide battery is 3.0V, and standing the battery for 2-10min after the constant current discharge is finished;
the fifth stage: charging with 0.5C constant current and voltage, wherein the voltage limit of the lithium iron phosphate battery is 3.7V, the voltage limit of the lithium nickel cobalt manganese oxide battery is 4.2V, the charging limit capacity is 30% of the rated capacity, the time is 90-120min, and the battery is placed for 2-10min after the constant current and voltage charging is finished;
the sixth stage: and (6) ending.
Further optimization: and taking the discharge capacity of the battery in the fourth stage in the step 3) as a matching capacity M.
Further optimization: after the capacity grading of the battery in the step 3) is finished, the battery is laid aside for 12-14h, then the voltage of the battery is measured, and the voltage of the battery is recorded as V1。
Further optimization: and 3) when the voltage of the battery is measured in the step 3), if the voltage of the lithium iron phosphate battery is lower than 3.2V, the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.5V, and the unqualified battery is picked out and is not circulated.
Further optimization: the temperature of the high-temperature holding chamber in the step 4) is 50 +/-2 ℃, and the holding time is 72-75 h.
By adopting the technical scheme, the capacity grading is carried out at the temperature of 42 +/-2 ℃ in consideration of careful and strict process, the problem of large capacity grading difference caused by temperature difference is effectively solved by fully considering the consistency of various indexes of the lithium ion battery in the group matching process, the battery with large self-discharge and micro short circuit can be effectively screened by adding the vibration process of the battery, the potential safety hazard of the battery is reduced, the safety and the overall performance of the battery are improved, the secondary reaction can be aggravated by placing the battery for 72h at high temperature after the capacity grading is finished, whether the battery can swell or not can be rapidly detected, the self-discharge battery can be further detected, and the defective battery can be conveniently selected out so as to improve the overall safety and the overall performance of the group-matched battery pack.
The present invention will be further described with reference to the following examples.
Detailed Description
Example 1:
a high-temperature capacity grading and matching process of a lithium ion battery specifically comprises the following steps:
1) charging and discharging for the first time: and connecting the formed battery to a charging and discharging cabinet, and carrying out full charging and full discharging for 2 times, wherein the ambient temperature is controlled at 23 ℃.
The design is mainly used for the internal reaction of the battery to be sufficient and the structure to be stable.
The constant-current discharging and constant-voltage charging adopted in the step 1) are used for full charging and full discharging, and the specific operation steps are as follows:
the first stage is as follows: the battery was left on the charging and discharging cabinet for 2 min.
And a second stage: and starting to discharge by using a 0.5C constant current for 150min, wherein the voltage limit is 2.0V when the battery is a lithium iron phosphate battery, and the voltage limit is 2.5V when the battery is a lithium nickel cobalt manganese oxide battery.
And a third stage: the battery was left on the charging and discharging cabinet for 2 min.
A fourth stage: and (3) charging by using a 0.5C constant current and constant voltage, wherein the current limit is 0.02C, and the time is 180min, wherein the voltage limit is 3.7V when the battery is a lithium iron phosphate battery, and the voltage limit is 4.2V when the battery is a lithium nickel cobalt manganese oxide battery.
The fifth stage: the battery was left on the charging and discharging cabinet for 2 min.
The sixth stage: and then discharging with a constant current of 0.5C for 150min, wherein the voltage limit is 2.0V when the battery is a lithium iron phosphate battery, and the voltage limit is 2.5V when the battery is a lithium nickel cobalt manganese oxide battery.
A seventh stage: the battery was left on the charging and discharging cabinet for 2 min.
An eighth stage: and circularly performing the fourth stage to the seventh stage once.
The ninth stage: and (6) ending.
After the first charge and discharge is completed, the battery is placed for 12 hours, then the voltage of the battery is measured, if the voltage of the lithium iron phosphate battery is lower than 2.7V, and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.2V, the unqualified battery is picked out, and circulation is not performed.
2) Vibration of the battery: and taking down the battery after the first charge and discharge on the discharge cabinet is completed, and fixedly placing the battery on a vibration table for vibration.
The vibration direction of the vibration table in the step 2) is single vibration up and down; the vibration frequency is 10 Hz; the acceleration is: 35m/s2(ii) a The vibration time is as follows: and 5 h.
When the battery vibrates in the step 2), the battery needs to be tightly and fixedly arranged in the vibration box, and the battery pole is covered by an insulating material.
And (3) after the battery is vibrated in the step 2), the battery is placed for 2 hours, then the voltage of the battery is measured, if the voltage of the lithium iron phosphate battery is lower than 2.7V and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.2V, the unqualified battery is picked out and does not circulate.
3) Capacity grading: and connecting the battery after the battery vibration is finished to a charging and discharging cabinet, and carrying out capacity grading by adopting voltage limiting, current limiting and time limiting, wherein the temperature in the capacity grading stage is controlled at 40 ℃.
The capacity division is carried out in the step 3) by limiting the pressure, limiting the flow and limiting the time, and the specific operation steps are as follows:
the first stage is as follows: the battery was left on the charging and discharging cabinet for 2 min.
And a second stage: and starting to discharge with a constant current of 0.5C for 150min, wherein the voltage limit is 2.5V when the battery is a lithium iron phosphate battery, the voltage limit is 3.0V when the battery is a lithium nickel cobalt manganese oxide battery, and the battery is kept for 2min after the constant current discharge is finished.
And a third stage: and (3) charging with a 0.5C constant current and constant voltage, wherein the current limit is 0.02C, and the time is 180min, wherein the voltage limit is 3.7V when the battery is a lithium iron phosphate battery, the voltage limit is 4.2V when the battery is a lithium nickel cobalt manganese oxide battery, and the battery is placed for 2min after the constant current and constant voltage charging is finished.
A fourth stage: discharging with 0.5C constant current for 150min, wherein the voltage limit is 2.5V when the battery is lithium iron phosphate battery, and 3.0V when the battery is lithium nickel cobalt manganese oxide battery, and standing for 2min after the constant current discharge.
The fifth stage: charging with 0.5C constant current and voltage, wherein when the battery is a lithium iron phosphate battery, the voltage limit is 3.7V, when the battery is a lithium nickel cobalt manganese oxide battery, the voltage limit is 4.2V, the charging limit is 30% of the rated capacity, the time is 90min, and after the constant current and voltage charging is finished, the battery is placed for 2 min;
the sixth stage: and (6) ending.
And taking the discharge capacity of the battery in the fourth stage as the matching capacity M.
After the capacity grading of the battery in the step 3) is finished, the battery is placed for 12 hours, then the voltage of the battery is measured, and the voltage of the battery is recorded as V1。
When the voltage of the battery is measured in the step 3), if the voltage of the lithium iron phosphate battery is lower than 3.2V, and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.5V, the unqualified battery is picked out and is not circulated.
In the following, the effect of different temperatures on the battery capacity is referred to in connection with the experiments.
The experimental settings were: taking 3 batteries with the same specification, placing the batteries in different temperature environments, and checking the discharge capacity of the batteries, wherein the environment temperatures are respectively set to be 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃, 45 ℃ and 50 ℃.
The following table is a table of the difference in battery capacity for different temperatures:
according to experimental data summarization, the battery is low in influence of temperature on battery capacity in an environment of 40-45 ℃, and the internal structure of the battery is easy to damage after the temperature exceeds 50 ℃.
In the prior art, the temperature of most capacity-grading workshops is adjusted by air conditioners, the fluctuation is 5 ℃ from top to bottom, and the fluctuation of the battery capacity is large.
However, when the ambient temperature fluctuates between 40 ℃ and 45 ℃, the ambient temperature has little change to the capacity of the battery, the obtained capacity data is more accurate, and the consistency is better when the battery is matched and used.
4) High-temperature laying aside: transferring the battery into a high-temperature holding chamber, wherein the temperature of the high-temperature holding chamber is 48 ℃, and the holding time is 72 hours.
5) Standing at normal temperature: and after the high-temperature shelf is finished, transferring the battery to a room-temperature shelf room, wherein the shelf time is 96 h.
6) Measuring voltage and internal resistance: after the laying aside is finished, the voltage V of the battery begins to be measured2Internal resistance R and thickness H, and recording.
In the step 6), when the pressure drop rate is calculated, the calculation formula of the pressure drop rate is Δ V = (V)1-V2）/5。
7) Recording the capacity M, the internal resistance R, the thickness H, the voltage drop rate delta V and the initial voltage V2And summarizing, and matching and delivering according to the matching requirements.
Example 2:
a high-temperature capacity grading and matching process of a lithium ion battery specifically comprises the following steps:
1) charging and discharging for the first time: and connecting the formed battery to a charging and discharging cabinet, and carrying out full charging and full discharging for 3 times, wherein the ambient temperature is controlled at 25 ℃.
The design is mainly used for the internal reaction of the battery to be sufficient and the structure to be stable.
The constant-current discharging and constant-voltage charging adopted in the step 1) are used for full charging and full discharging, and the specific operation steps are as follows:
the first stage is as follows: the battery was left on the charging and discharging cabinet for 6 min.
And a second stage: and starting to discharge by using a 0.5C constant current for 175min, wherein the voltage limit is 2.0V when the battery is a lithium iron phosphate battery, and the voltage limit is 2.5V when the battery is a lithium nickel cobalt manganese oxide battery.
And a third stage: the battery was left on the charging and discharging cabinet for 6 min.
A fourth stage: and (3) charging by using a 0.5C constant current and constant voltage, wherein the current limit is 0.02C, and the time is 190min, wherein the voltage limit is 3.7V when the battery is a lithium iron phosphate battery, and the voltage limit is 4.2V when the battery is a lithium nickel cobalt manganese oxide battery.
The fifth stage: the battery was left on the charging and discharging cabinet for 6 min.
The sixth stage: and then discharging with a constant current of 0.5C for 175min, wherein the voltage limit is 2.0V when the battery is a lithium iron phosphate battery, and the voltage limit is 2.5V when the battery is a lithium nickel cobalt manganese oxide battery.
A seventh stage: the battery was left on the charging and discharging cabinet for 6 min.
An eighth stage: the fourth stage to the seventh stage are cyclically performed for 2 times.
The ninth stage: and (6) ending.
After the first charge and discharge is completed, the battery is placed for 13 hours, then the voltage of the battery is measured, if the voltage of the lithium iron phosphate battery is lower than 2.7V, the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.2V, the unqualified battery is picked out, and circulation is not performed.
2) Vibration of the battery: and taking down the battery after the first charge and discharge on the discharge cabinet is completed, and fixedly placing the battery on a vibration table for vibration.
The vibration direction of the vibration table in the step 2) is single vibration up and down; the vibration frequency is 30 Hz; the acceleration is: 30m/s2(ii) a The vibration time is as follows: and 4 h.
When the battery vibrates in the step 2), the battery needs to be tightly and fixedly arranged in the vibration box, and the battery pole is covered by an insulating material.
And (3) after the battery is vibrated in the step 2), the battery is placed for 3 hours, then the voltage of the battery is measured, if the voltage of the lithium iron phosphate battery is lower than 2.7V and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.2V, the unqualified battery is picked out and does not circulate.
3) Capacity grading: and connecting the battery after the battery vibration is finished to a charging and discharging cabinet, and carrying out capacity grading by adopting pressure limiting, current limiting and time limiting, wherein the temperature in the capacity grading stage is controlled at 42 ℃.
The capacity division is carried out in the step 3) by limiting the pressure, limiting the flow and limiting the time, and the specific operation steps are as follows:
the first stage is as follows: the battery was left on the charging and discharging cabinet for 6 min.
And a second stage: and starting to discharge by using a 0.5C constant current for 175min, wherein the voltage limit is 2.5V when the battery is a lithium iron phosphate battery, the voltage limit is 3.0V when the battery is a lithium nickel cobalt manganese oxide battery, and the battery is kept for 6min after the constant current discharge is finished.
And a third stage: and (3) charging by using a 0.5C constant current and constant voltage, wherein the current limit is 0.02C, the time is 190min, the voltage limit is 3.7V when the battery is a lithium iron phosphate battery, the voltage limit is 4.2V when the battery is a lithium nickel cobalt manganese oxide battery, and the battery is placed for 6min after the constant current and constant voltage charging is finished.
A fourth stage: discharging with 0.5C constant current for 175min, wherein the voltage limit is 2.5V when the battery is lithium iron phosphate battery, and 3.0V when the battery is lithium nickel cobalt manganese oxide battery, and standing for 6min after the constant current discharge.
The fifth stage: charging with 0.5C constant current and voltage, wherein when the battery is a lithium iron phosphate battery, the voltage limit is 3.7V, when the battery is a lithium nickel cobalt manganese oxide battery, the voltage limit is 4.2V, the charging limit is 30% of the rated capacity, the time is 105min, and after the constant current and voltage charging is finished, the battery is placed for 6 min;
the sixth stage: and (6) ending.
And taking the discharge capacity of the battery in the fourth stage as the matching capacity M.
After the capacity grading of the battery in the step 3) is finished, the battery is placed for 13h, then the voltage of the battery is measured, and the voltage of the battery is recorded as V1。
When the voltage of the battery is measured in the step 3), if the voltage of the lithium iron phosphate battery is lower than 3.2V, and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.5V, the unqualified battery is picked out and is not circulated.
4) High-temperature laying aside: the battery is transferred into a high-temperature resting chamber, the temperature of the high-temperature resting chamber is 50 ℃, and the resting time is 73.5 hours.
5) Standing at normal temperature: and after the high-temperature shelf is finished, the battery is transferred to a room-temperature shelf for 98 h.
6) Measuring voltage and internal resistance: after the laying aside is finished, the voltage V of the battery begins to be measured2Internal resistance R and thickness H, and recording.
In the step 6), when the pressure drop rate is calculated, the calculation formula of the pressure drop rate is Δ V = (V)1-V2）/5。
7) Recording the capacity M, the internal resistance R, the thickness H, the voltage drop rate delta V and the initial voltage V2And summarizing, and matching and delivering according to the matching requirements.
Example 3:
a high-temperature capacity grading and matching process of a lithium ion battery specifically comprises the following steps:
1) charging and discharging for the first time: and connecting the formed battery to a charging and discharging cabinet, and carrying out full charging and full discharging for 4 times, wherein the ambient temperature is controlled at 27 ℃.
The design is mainly used for the internal reaction of the battery to be sufficient and the structure to be stable.
The constant-current discharging and constant-voltage charging adopted in the step 1) are used for full charging and full discharging, and the specific operation steps are as follows:
the first stage is as follows: the battery was left on the charging and discharging cabinet for 10 min.
And a second stage: and starting to discharge by using a 0.5C constant current for 200min, wherein the voltage limit is 2.0V when the battery is a lithium iron phosphate battery, and the voltage limit is 2.5V when the battery is a lithium nickel cobalt manganese oxide battery.
And a third stage: the battery was left on the charging and discharging cabinet for 10 min.
A fourth stage: and (3) charging by using a 0.5C constant current and constant voltage, wherein the current limit is 0.02C, and the time is 200min, wherein the voltage limit is 3.7V when the battery is a lithium iron phosphate battery, and the voltage limit is 4.2V when the battery is a lithium nickel cobalt manganese oxide battery.
The fifth stage: the battery was left on the charging and discharging cabinet for 10 min.
The sixth stage: and then discharging with a constant current of 0.5C for 200min, wherein the voltage limit is 2.0V when the battery is a lithium iron phosphate battery, and the voltage limit is 2.5V when the battery is a lithium nickel cobalt manganese oxide battery.
A seventh stage: the battery is placed on a charging and discharging cabinet for 100 min.
An eighth stage: the fourth to seventh stages are cyclically performed 3 times.
The ninth stage: and (6) ending.
After the first charge and discharge is completed, the battery is placed for 14 hours, then the voltage of the battery is measured, if the voltage of the lithium iron phosphate battery is lower than 2.7V, and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.2V, the unqualified battery is picked out, and circulation is not performed.
2) Vibration of the battery: and taking down the battery after the first charge and discharge on the discharge cabinet is completed, and fixedly placing the battery on a vibration table for vibration.
The vibration direction of the vibration table in the step 2) is single vibration up and down; the vibration frequency is 50 Hz; the acceleration is: 25m/s2(ii) a The vibration time is as follows: and 3 h.
When the battery vibrates in the step 2), the battery needs to be tightly and fixedly arranged in the vibration box, and the battery pole is covered by an insulating material.
And (3) after the battery is vibrated in the step 2), the battery is placed for 4 hours, then the voltage of the battery is measured, if the voltage of the lithium iron phosphate battery is lower than 2.7V and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.2V, the unqualified battery is picked out and does not circulate.
3) Capacity grading: and connecting the battery after the battery vibration is finished to a charging and discharging cabinet, and carrying out capacity grading by adopting voltage limiting, current limiting and time limiting, wherein the temperature in the capacity grading stage is controlled at 44 ℃.
The capacity division is carried out in the step 3) by limiting the pressure, limiting the flow and limiting the time, and the specific operation steps are as follows:
the first stage is as follows: the battery was left on the charging and discharging cabinet for 10 min.
And a second stage: and starting to discharge with a constant current of 0.5C for 200min, wherein the voltage limit is 2.5V when the battery is a lithium iron phosphate battery, the voltage limit is 3.0V when the battery is a lithium nickel cobalt manganese oxide battery, and the battery is kept for 10min after the constant current discharge is finished.
And a third stage: and (3) charging with a 0.5C constant current and constant voltage, wherein the current limit is 0.02C, the time is 200min, the voltage limit is 3.7V when the battery is a lithium iron phosphate battery, the voltage limit is 4.2V when the battery is a lithium nickel cobalt manganese oxide battery, and the battery is placed for 10min after the constant current and constant voltage charging is finished.
A fourth stage: discharging with 0.5C constant current for 200min, wherein the voltage limit is 2.5V when the battery is lithium iron phosphate battery, and 3.0V when the battery is lithium nickel cobalt manganese oxide battery, and standing for 10min after the constant current discharge.
The fifth stage: charging with 0.5C constant current and voltage, wherein when the battery is a lithium iron phosphate battery, the voltage limit is 3.7V, when the battery is a lithium nickel cobalt manganese oxide battery, the voltage limit is 4.2V, the charging limit is 30% of the rated capacity, the time is 120min, and after the constant current and voltage charging is finished, the battery is placed for 10 min;
the sixth stage: and (6) ending.
And taking the discharge capacity of the battery in the fourth stage as the matching capacity M.
After the capacity grading of the battery in the step 3) is finished, the battery is laid for 14h, then the voltage of the battery is measured, and the voltage of the battery is recorded as V1。
When the voltage of the battery is measured in the step 3), if the voltage of the lithium iron phosphate battery is lower than 3.2V, and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.5V, the unqualified battery is picked out and is not circulated.
4) High-temperature laying aside: the battery is transferred into a high-temperature resting chamber, the temperature of the high-temperature resting chamber is 52 ℃, and the resting time is 75 h.
5) Standing at normal temperature: and after the high-temperature shelf is finished, transferring the battery to a room-temperature shelf for 100 hours.
6) Measuring voltage and internal resistance: after the laying aside is finished, the voltage V of the battery begins to be measured2Internal resistance R and thickness H, and recording.
In the step 6), when the pressure drop rate is calculated, the calculation formula of the pressure drop rate is Δ V = (V)1-V2）/5。
7) Recording the capacity M, the internal resistance R, the thickness H, the voltage drop rate delta V and the initial voltage V2And summarizing, and matching and delivering according to the matching requirements.
By adopting the technical scheme, the capacity grading is carried out at the temperature of 42 +/-2 ℃ in consideration of careful and strict process, the problem of large capacity grading difference caused by temperature difference is effectively solved by fully considering the consistency of various indexes of the lithium ion battery in the group matching process, the battery with large self-discharge and micro short circuit can be effectively screened by adding the vibration process of the battery, the potential safety hazard of the battery is reduced, the safety and the overall performance of the battery are improved, the secondary reaction can be aggravated by placing the battery for 72h at high temperature after the capacity grading is finished, whether the battery can swell or not can be rapidly detected, the self-discharge battery can be further detected, and the defective battery can be conveniently selected out so as to improve the overall safety and the overall performance of the group-matched battery pack.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (6)
1. A high-temperature capacity grading and matching process of a lithium ion battery is characterized in that: the process specifically comprises the following steps:
1) charging and discharging for the first time: connecting the formed battery to a charging and discharging cabinet, and carrying out full charging and full discharging for 2-4 times, wherein the environmental temperature is controlled to be 25 +/-2 ℃;
the specific operation steps of the first charging and discharging in the step 1) are as follows:
the first stage is as follows: placing the battery on a cabinet for 2-10 min;
and a second stage: starting to discharge by using a constant current of 0.5 ℃ for 150-200min, wherein the voltage limit of the lithium iron phosphate battery is 2.0V, and the voltage limit of the lithium nickel cobalt manganese oxide battery is 2.5V;
and a third stage: laying aside the battery for 2-10 min;
a fourth stage: charging with 0.5C constant current and constant voltage, with the current limit of 0.02C and the time of 180-200min, wherein the voltage limit of the lithium iron phosphate battery is 3.7V, and the voltage limit of the lithium nickel cobalt manganese oxide battery is 4.2V;
the fifth stage: laying aside the battery for 2-10 min;
the sixth stage: discharging with constant current of 0.5 deg.C for 200 min; wherein the voltage limit of the lithium iron phosphate battery is 2.0V, and the voltage limit of the lithium nickel cobalt manganese oxide battery is 2.5V;
a seventh stage: the battery is placed on a charging and discharging cabinet for 2-10 min;
an eighth stage: circularly performing the fourth stage to the seventh stage for 1-3 times;
the ninth stage: finishing;
after the first charge and discharge is finished, the battery is placed for 12-14h, the voltage of the battery is measured, if the voltage of the lithium iron phosphate battery is lower than 2.7V, and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.2V, the battery is unqualified, and is picked out without circulation;
2) vibration of the battery: fixedly placing the battery after the first charge and discharge on a vibration table for vibration;
3) capacity grading: connecting the battery after the battery vibration is finished to a charging and discharging cabinet, and carrying out capacity grading by adopting pressure limiting, current limiting and time limiting, wherein the temperature in the capacity grading stage is controlled to be 42 +/-2 ℃;
the specific operation steps of pressure limiting, current limiting and time limiting capacity grading in the step 3) are as follows:
the first stage is as follows: the battery is placed on the upper cabinet for 2-10 min;
and a second stage: starting to discharge by using a 0.5C constant current for 150-200min, wherein the voltage limit of the lithium iron phosphate battery is 2.5V, the voltage limit of the lithium nickel cobalt manganese oxide battery is 3.0V, and standing the battery for 2-10min after the constant current discharge is finished;
and a third stage: charging with 0.5C constant current and constant voltage, with the current limit of 0.02C and the time of 180-200min, wherein the voltage limit of the lithium iron phosphate battery is 3.7V, the voltage limit of the lithium nickel cobalt manganese oxide battery is 4.2V, and the battery is placed for 2-10min after the constant current and constant voltage charging is finished;
a fourth stage: discharging with constant current of 0.5 ℃ for 200min, wherein the voltage limit of the lithium iron phosphate battery is 2.5V, the voltage limit of the lithium nickel cobalt manganese oxide battery is 3.0V, and standing the battery for 2-10min after the constant current discharge is finished;
the fifth stage: charging with 0.5C constant current and voltage, wherein the voltage limit of the lithium iron phosphate battery is 3.7V, the voltage limit of the lithium nickel cobalt manganese oxide battery is 4.2V, the charging limit capacity is 30% of the rated capacity, the time is 90-120min, and the battery is placed for 2-10min after the constant current and voltage charging is finished;
the sixth stage: finishing;
after the capacity grading of the battery in the step 3) is finished, the battery is laid aside for 12-14h, then the voltage of the battery is measured, and the voltage of the battery is recorded as V1；
4) High-temperature laying aside: transferring the battery into a high-temperature shelving chamber for high-temperature shelving;
5) standing at normal temperature: after the high-temperature shelf is finished, transferring the battery to a room-temperature shelf room for normal-temperature shelf, wherein the shelf time is 96-100 h;
6) measuring voltage and internal resistance: after the laying aside is finished, the voltage V of the battery begins to be measured2Internal resistance R and thickness H, recording and recording according to the measured voltage V of the battery1、And V2And calculating the pressure drop rate according to the resting time;
7) recording the capacity M, the internal resistance R, the thickness H, the voltage drop rate and the initial voltage V2And summarizing, and carrying out matching delivery according to the matching requirement.
2. The high-temperature capacity grading and grouping process of the lithium ion battery according to claim 1, characterized in that: the vibration direction of the vibration table in the step 2) is single vibration up and down; the vibration frequency is 10-50 Hz; the acceleration is: 25-35m/s2(ii) a The vibration time is as follows: 3-5 h.
3. The high-temperature capacity grading and grouping process of the lithium ion battery according to claim 2, characterized in that: and (3) after the battery in the step 2) is vibrated, standing the battery for 2-4h, measuring the voltage of the battery, and if the voltage of the lithium iron phosphate battery is lower than 2.7V and the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.2V, sorting out the battery without circulation.
4. The high-temperature capacity grading and grouping process of the lithium ion battery according to claim 3, characterized in that: and taking the discharge capacity of the battery in the fourth stage in the step 3) as a matching capacity M.
5. The high-temperature capacity grading and grouping process of the lithium ion battery according to claim 4, characterized in that: and 3) when the voltage of the battery is measured in the step 3), if the voltage of the lithium iron phosphate battery is lower than 3.2V, the voltage of the lithium nickel cobalt manganese oxide battery is lower than 3.5V, and the unqualified battery is picked out and is not circulated.
6. The high-temperature capacity grading and grouping process of the lithium ion battery according to claim 5, characterized in that: the temperature of the high-temperature holding chamber in the step 4) is 50 +/-2 ℃, and the holding time is 72-75 h.
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