CN110672704A - Identification method for rapidly judging damage of soft package lithium ion battery aluminum plastic film - Google Patents
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Abstract
The invention provides an identification method for rapidly judging the damage of an aluminum-plastic film of a soft package lithium ion battery, which is characterized in that a positive electrode tab is directly welded with the aluminum-plastic film to be connected with an aluminum layer of an intermediate layer of the aluminum-plastic film, if the aluminum-plastic film is damaged, the internal micro short circuit of a battery cell can be caused, so that current passes through abnormal heat sealing areas, the internal resistance of the battery is increased, the voltage drop in unit time exceeds a specified measurement range, and the yield condition of the battery cell is rapidly detected.
Description
Technical Field
The invention relates to the technical field of lithium ion battery detection, in particular to an identification method for rapidly judging the damage of an aluminum plastic film of a soft package lithium ion battery.
Background
The aluminum-plastic film is a composite material formed by an outer protective layer, a middle aluminum layer and an inner heat sealing layer, and the layers are pressed and bonded through an adhesive. The aluminum plastic film is a key material for packaging the battery core of the flexible package lithium battery, the single battery is assembled and then sealed by the aluminum plastic film to form the battery, and the aluminum plastic film plays a role in protecting contents.
The internal corrosion of the aluminum-plastic film can cause short circuit risk, the essence of electrochemical corrosion is that the aluminum-plastic film PP is damaged, and then the aluminum film is corroded by electrolyte, so that the aluminum-plastic film in the area is damaged by corrosion, and the aluminum layer is electrified to be at a lower potential, so that the lithium-embedded alloy is formed. Finally causing the safety accident of liquid leakage.
Chinese patent application publication No. CN103048376A, published as 2013.04.17, discloses a method for detecting corrosion in a flexible package lithium ion battery, which comprises the steps of measuring the voltage between the positive electrode and the negative electrode of the lithium ion battery and the voltage between the positive electrode tab and an aluminum-plastic composite film by using a voltmeter, comparing the measured voltages, and if the voltage between the positive electrode tab and the aluminum layer is equal to or slightly less than the theoretical voltage value of the battery, the aluminum layer in the aluminum-plastic film is necessarily subjected to internal corrosion; or the resistance between the positive electrode lug and the aluminum layer of the aluminum plastic film is measured by a multimeter more simply, and if the measured resistance value is less than 100 omega, internal corrosion occurs. The method has the disadvantages that the method needs to be carried out in a full-charge state of the finished battery, the battery can be detected only by laying aside for more than one day, the heat sealing effect of the aluminum plastic film cannot be rapidly detected, and the detection period is long. In addition, the method has certain uncertainty because the electrolyte is required to be present at the damaged position of the aluminum-plastic film to measure the voltage difference. The distribution of the electrolyte in the aluminum-plastic film has uncertainty, so the method has the possibility of missing detection.
The application publication No. CN104330710A discloses a method for rapidly judging poor insulation of a soft package lithium ion battery aluminum-plastic film, wherein a probe is inserted into any edge sealing of the soft package lithium ion battery to be in contact with an aluminum layer of the aluminum-plastic film, and the probe and a positive lug or a negative lug of the soft package lithium ion battery are respectively connected with two poles of an adjustable voltage direct current power supply through a lead, wherein the voltage of the adjustable voltage direct current power supply is more than or equal to 400V; (2) and starting a power supply, if the liquid leakage, the breakdown or the smoke phenomenon occurs in the edge sealing of the soft package lithium ion battery, indicating that the aluminum-plastic film at the position of the edge sealing is poor in insulation, and if the liquid leakage, the breakdown or the smoke phenomenon does not occur in the edge sealing of the soft package lithium ion battery, indicating that the aluminum-plastic film at the edge sealing of the soft package lithium ion battery is good in insulation. The method has the disadvantages that the single detection speed is low, so that the period is long when a large number of electric cores are detected, the electric core test operation needs proficiency, and automatic detection cannot be realized.
Disclosure of Invention
The invention aims to solve the problems so as to meet the requirement of rapidly and safely judging whether the battery cell is short-circuited in actual production. The following technical scheme is adopted:
an identification method for rapidly judging the damage of a soft package lithium ion battery aluminum plastic film comprises the following steps:
s1, welding: after the battery cell is packaged, welding a positive electrode lug and an aluminum-plastic film to enable the positive electrode lug to be in contact with a middle aluminum layer of the aluminum-plastic film;
s2, sealing: sealing the welding position of the battery cell after welding is finished;
s3, testing: performing a current test or an OCV test on the battery cell processed in step S2;
s4, judgment: checking whether the current or the voltage drop of the battery cell exceeds a normal range, and checking whether the appearance of the battery cell is abnormal; if the current appears, or the voltage drop exceeds the normal range, or the appearance of the battery cell is abnormal, the inside of the battery cell is corroded, and the aluminum-plastic film is damaged.
The working principle of the invention is as follows: the aluminium-plastic film takes place the damage, can cause the middle aluminium lamination of negative pole utmost point ear and aluminium-plastic film to switch on, forms little electron channel, and anodal utmost point ear switches on through the welding with the aluminium-plastic film and forms electron channel, therefore the anodal of lithium cell can link to each other with the negative pole reality and form local little short circuit. The reaction equation is as follows: al + Li++e-LiAl. The self-discharge phenomenon can occur in the lithium battery core, the internal resistance of the battery core is increased, and the voltage is reduced. And carrying out current or OCV test on the welded battery cell, and judging whether the inside of the battery cell is corroded or not and whether the aluminum plastic film is damaged or not by testing whether current passes between the positive electrode and the negative electrode or not or whether the voltage drop of the battery cell exceeds a normal range. If the battery core is abnormal in the testing process, the properties are changed, and the aluminum plastic film is damaged.
The method disclosed by the invention is simple in principle and operation, has no requirement on the electric quantity state of the battery cell, is short in detection time, and can be used for quickly and conveniently detecting whether the aluminum plastic film is damaged.
Further, in step S1, the outer protection layer and the inner heat seal layer of the aluminum-plastic film are broken through by welding to expose the intermediate aluminum layer, and then the positive electrode tab is in welding contact with the intermediate aluminum layer of the aluminum-plastic film to form an electronic channel.
Furthermore, the welding in step S1 adopts laser welding, which has high speed, large depth, small deformation and high precision.
Further, the power density of the laser welding is in the range of 104～106W/cm2。
Further, in the step S2, the sealing process is performed by dropping conductive oil at the welding position of the battery core, and the conductive oil plays two roles, namely, conducting the positive electrode tab and the aluminum layer, and sealing and isolating the welding position of the positive electrode tab from air.
Further, the conductive oil is conductive silver oil, conductive copper oil, conductive nickel oil or conductive silver copper oil.
Further, the OCV test in step S3 specifically includes: respectively connecting the positive electrode tab and the negative electrode tab of the soft package lithium ion battery with two electrodes of a voltage testing device through leads, measuring the voltage OCV between the positive electrode and the negative electrode, and measuring the voltage OCV at time t1OCV measurement1Time t2OCV measurement2Voltage drop K ═ OCV (OCV)1-OCV2)/(t2-t1)。
Further, the step S4 of exceeding the normal range by the voltage drop of the battery cell specifically includes: the voltage drop K of two voltage tests is more than 0.05 mV/h.
Further, the current test in step S3 specifically includes: and respectively connecting the positive electrode lug and the negative electrode lug of the soft package lithium ion battery with two electrodes of a current testing device through leads, and measuring the current between the positive electrode and the negative electrode.
Further, the step S3 is to determine that the battery cell appearance is abnormal specifically: the edge sealing of the soft package lithium ion battery has the phenomena of liquid leakage, breakdown or smoking.
The invention can obtain the following beneficial effects:
1. according to the invention, the positive electrode tab is welded with the aluminum-plastic film, the state judgment of the aluminum-plastic film is converted into the voltage drop of the battery in unit time for judgment by measuring the voltage drop between the positive electrode and the negative electrode or measuring whether current passes between the positive electrode and the negative electrode, the concept is novel, and the aluminum-plastic film of the soft package lithium battery can be rapidly inspected for damage or not, so that the mass production is realized.
2. The method has the advantages of simple principle and convenient operation, can conveniently realize the detection of the corrosion in the lithium ion battery, and provides a good technical basis for improving the quality of the battery.
3. The invention can detect the battery at any time without detecting the battery in a full-charge state, and has wide application range.
4. The invention is a non-destructive detection method, which can not cause damage to the normal use of the battery and can not influence the use performance of the battery.
5. The detection method can detect the unqualified batteries on the production line in time, and prevent the unqualified products from flowing into the market.
Drawings
Fig. 1 is a schematic diagram of a front structure of a battery cell according to the present invention;
fig. 2 is a schematic diagram of a cell welding structure according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
According to the soft package lithium ion battery provided by the embodiment of the invention, the anode tab is made of an Al material, the cathode tab is made of a Ni material, the outer protection layer of the aluminum plastic film is made of a nylon material, and the inner heat sealing layer is made of a PP (polypropylene) material.
Example 1:
as shown in fig. 1 and 2, an identification method for rapidly judging soft package lithium ion battery aluminum plastic film damage includes the following steps:
s1, welding: after the battery cell is packaged, welding a positive electrode lug and an aluminum-plastic film to enable the positive electrode lug to be in contact with a middle aluminum layer of the aluminum-plastic film;
s2, sealing: sealing the welding position of the battery cell after welding is finished;
s3, testing: performing current test on the battery cell processed in the step S2, respectively connecting a positive electrode tab and a negative electrode tab of the soft package lithium ion battery with two electrodes of a direct current ammeter through leads, and measuring the current between the positive electrode and the negative electrode;
s4, judgment: checking whether current appears or not, and checking whether the appearance of the battery cell is abnormal or not; if the direct current ammeter has no indication, the aluminum-plastic film is complete, and the electrical core is well insulated; if the direct current ammeter shows numbers or the appearance of the battery cell is abnormal, the inside of the battery cell is corroded, and the aluminum-plastic film is damaged.
Example 2:
as shown in fig. 1 and 2, an identification method for rapidly judging soft package lithium ion battery aluminum plastic film damage includes the following steps:
s1, welding: after the battery cell is packaged, laser welding is carried out on the position of the positive electrode tab and the position of the aluminum-plastic film, an outer protection layer and an inner heat sealing layer of the aluminum-plastic film are broken through laser, so that an intermediate aluminum layer is exposed, and the positive electrode tab is in welding contact with the intermediate aluminum layer of the aluminum-plastic film;
s2, sealing: after welding, dripping conductive copper oil at the welding position of the battery cell to isolate air at the welding position of the positive electrode lug, and simultaneously conducting the positive electrode lug and the aluminum layer to play a role in conducting electricity;
s3, testing: performing current test on the battery cell processed in the step S2, respectively connecting a positive electrode tab and a negative electrode tab of the soft package lithium ion battery with two electrodes of a universal meter through leads, and measuring the current between the positive electrode and the negative electrode at a direct current gear;
s4, judgment: checking whether current appears or not, if the multimeter has no registration, indicating that the aluminum plastic film is complete and the electrical core is well insulated; if the number indicating is carried out by the universal meter, or the phenomena of liquid leakage, breakdown or smoking occur at the edge sealing of the soft package lithium ion battery, the inside of the battery core is corroded, and the aluminum plastic film is damaged.
Example 3:
as shown in fig. 1 and 2, an identification method for rapidly judging soft package lithium ion battery aluminum plastic film damage includes the following steps:
s1, welding: after the battery cell is packaged, laser welding is carried out on the positive electrode lug and the aluminum plastic film, and the power density of the laser welding is 104W/cm2The outer protective layer and the inner heat-sealing layer of the aluminum-plastic film are broken down through laser to expose the middle aluminum layer, so that the positive electrode tab is in welding contact with the middle aluminum layer of the aluminum-plastic film;
s2, sealing: after welding, the conductive silver oil is dropped at the welding position of the battery cell, so that the welding position of the positive electrode lug is isolated from air, and the positive electrode lug is conducted with the aluminum layer to play a role in conducting electricity;
s3, testing: performing current test on the battery cell processed in the step S2, respectively connecting a positive electrode tab and a negative electrode tab of the soft package lithium ion battery with two electrodes of a universal meter through leads, and measuring the current between the positive electrode and the negative electrode at a direct current gear;
s4, judgment: checking whether current appears or not, if the multimeter has no registration, indicating that the aluminum plastic film is complete and the electrical core is well insulated; if the number indicating is carried out by the universal meter, or the phenomena of liquid leakage, breakdown or smoking occur at the edge sealing of the soft package lithium ion battery, the inside of the battery core is corroded, and the aluminum plastic film is damaged.
Example 4:
as shown in fig. 1 and 2, an identification method for rapidly judging soft package lithium ion battery aluminum plastic film damage includes the following steps:
s1, welding: after the battery cell is packaged, laser welding is carried out on the position of the positive electrode tab and the position of the aluminum-plastic film, an outer protection layer and an inner heat sealing layer of the aluminum-plastic film are broken through laser, so that an intermediate aluminum layer is exposed, and the positive electrode tab is in welding contact with the intermediate aluminum layer of the aluminum-plastic film;
s2, sealing: after welding, dripping conductive copper oil at the welding position of the battery cell to isolate air at the welding position of the positive electrode lug, and simultaneously conducting the positive electrode lug and the aluminum layer to play a role in conducting electricity;
s3, testing: performing OCV test on the battery cell processed in the step S2, respectively connecting the positive electrode tab and the negative electrode tab of the soft package lithium ion battery with two electrodes of a direct current voltmeter through leads, measuring the voltage OCV between the positive electrode and the negative electrode, and measuring the voltage OCV at the time t1OCV measurement1Time t2OCV measurement2Voltage drop K ═ OCV (OCV)1-OCV2)/(t2-t1) Wherein t is2-t1＝2h；
S4, judgment: checking whether the voltage drop K of the battery cell exceeds a normal range, and if the voltage drop K is less than or equal to 0.05mV/h, indicating that the aluminum-plastic film is complete and the battery cell is well insulated; and if K is more than 0.05mV/h, the inside of the battery cell is corroded, and the aluminum-plastic film is damaged.
Example 5:
as shown in fig. 1 and 2, an identification method for rapidly judging soft package lithium ion battery aluminum plastic film damage includes the following steps:
s1, welding: after the battery cell is packaged, laser welding is carried out on the position of the positive electrode tab and the position of the aluminum-plastic film, an outer protection layer and an inner heat sealing layer of the aluminum-plastic film are broken through laser, so that an intermediate aluminum layer is exposed, and the positive electrode tab is in welding contact with the intermediate aluminum layer of the aluminum-plastic film;
s2, sealing: after welding, the conductive silver oil is dropped at the welding position of the battery cell, so that the welding position of the positive electrode lug is isolated from air, and the positive electrode lug is conducted with the aluminum layer to play a role in conducting electricity;
s3, testing: performing OCV test on the battery cell processed in the step S2, respectively connecting a positive electrode tab and a negative electrode tab of the soft package lithium ion battery with two electrodes of a universal meter through a lead, measuring voltage OCV between the positive electrode and the negative electrode at a direct current voltage gear, and measuring the voltage OCV at time t1OCV measurement1Time t2OCV measurement2Voltage drop K ═ OCV (OCV)1-OCV2)/(t2-t1) Wherein t is2-t1＝5h；
S4, judgment: checking whether the voltage drop K of the battery cell exceeds a normal range, and checking whether the appearance of the battery cell is abnormal; if K is less than or equal to 0.05mV/h or the appearance of the battery cell is good and has no abnormity, the aluminum-plastic film is complete and the battery cell is good in insulation; if K is more than 0.05mV/h or the phenomena of liquid leakage, breakdown or smoking occur at the edge sealing of the soft package lithium ion battery, the inside of the battery cell is corroded, and the aluminum plastic film is damaged.
Example 6:
as shown in fig. 1 and 2, an identification method for rapidly judging soft package lithium ion battery aluminum plastic film damage includes the following steps:
s1, welding: after the battery cell is packaged, laser welding is carried out on the positive electrode lug and the aluminum plastic film, and the power density of the laser welding is within the range of 2 multiplied by 104W/cm2The outer protective layer and the inner heat-sealing layer of the aluminum-plastic film are broken down through laser to expose the middle aluminum layer, so that the positive electrode tab and the middle aluminum layer of the aluminum-plastic film are welded together;
s2, sealing: after welding, dripping conductive nickel oil at the welding position of the battery cell to isolate air at the welding position of the positive electrode lug, and simultaneously conducting the positive electrode lug and the aluminum layer to play a role of conducting electricity;
s3, testing: performing OCV test on the battery cell processed in the step S2, respectively connecting a positive electrode tab and a negative electrode tab of the soft package lithium ion battery with two electrodes of a universal meter through a lead, measuring voltage OCV between the positive electrode and the negative electrode at a direct current voltage gear, and measuring the voltage OCV at time t1OCV measurement1Time t2OCV measurement2Voltage drop K ═ OCV (OCV)1-OCV2)/(t2-t1) Wherein t is2-t1＝10h；
S4, judgment: checking whether the voltage drop K of the battery cell exceeds a normal range, and checking whether the appearance of the battery cell is abnormal; if K is less than or equal to 0.05mV/h or the appearance of the battery cell is good and has no abnormity, the aluminum-plastic film is complete and the battery cell is good in insulation; if K is more than 0.05mV/h or the phenomena of liquid leakage, breakdown or smoking occur at the edge sealing of the soft package lithium ion battery, the inside of the battery cell is corroded, and the aluminum plastic film is damaged.
Example 7:
as shown in fig. 1 and 2, an identification method for rapidly judging soft package lithium ion battery aluminum plastic film damage includes the following steps:
s1, welding: after the battery cell is packaged, laser welding is carried out on the positive electrode lug and the aluminum plastic film, and the power density of the laser welding is within the range of 5 multiplied by 104W/cm2The outer protective layer and the inner heat-sealing layer of the aluminum-plastic film are broken down through laser to expose the middle aluminum layer, so that the positive electrode tab is in welding contact with the middle aluminum layer of the aluminum-plastic film;
s2, sealing: after welding, dripping conductive silver and copper oil at the welding position of the battery cell, sealing and isolating the welding position of the positive electrode lug from air, and conducting the positive electrode lug and the aluminum layer to play a role in conducting electricity;
s3, testing: performing OCV test on the battery cell processed in the step S2, respectively connecting a positive electrode tab and a negative electrode tab of the soft package lithium ion battery with two electrodes of a universal meter through a lead, measuring voltage OCV between the positive electrode and the negative electrode at a direct current voltage gear, and measuring the voltage OCV at time t1OCV measurement1Time t2OCV measurement2Voltage drop K ═ OCV (OCV)1-OCV2)/(t2-t1) Wherein t is2-t1＝16h；
S4, judgment: checking whether the voltage drop K of the battery cell exceeds a normal range, and checking whether the appearance of the battery cell is abnormal; if K is less than or equal to 0.05mV/h or the appearance of the battery cell is good and has no abnormity, the aluminum-plastic film is complete and the battery cell is good in insulation; if K is more than 0.05mV/h or the phenomena of liquid leakage, breakdown or smoking occur at the edge sealing of the soft package lithium ion battery, the inside of the battery cell is corroded, and the aluminum plastic film is damaged.
Example 8:
as shown in fig. 1 and 2, an identification method for rapidly judging soft package lithium ion battery aluminum plastic film damage includes the following steps:
s1, welding: after the battery cell is packaged, laser welding is carried out on the positive electrode lug and the aluminum plastic film, and the power density of the laser welding is within the range of 105W/cm2The outer protective layer and the inner heat-sealing layer of the aluminum-plastic film are broken down through laser to expose the middle aluminum layer, so that the positive electrode tab is in welding contact with the middle aluminum layer of the aluminum-plastic film;
s2, sealing: after welding, dripping conductive silver oil at the welding position of the battery cell, isolating the welding position of the positive electrode lug from air, sealing, and conducting the positive electrode lug and the aluminum layer to play a role in conducting electricity;
s3, testing: performing OCV test on the battery cell processed in the step S2, respectively connecting a positive electrode tab and a negative electrode tab of the soft package lithium ion battery with two electrodes of a universal meter through a lead, measuring voltage OCV between the positive electrode and the negative electrode at a direct current voltage gear, and measuring the voltage OCV at time t1OCV measurement1Time t2OCV measurement2Voltage drop K ═ OCV (OCV)1-OCV2)/(t2-t1) Wherein t is2-t1＝24h；
S4, judgment: checking whether the voltage drop K of the battery cell exceeds a normal range, and checking whether the appearance of the battery cell is abnormal; if K is less than or equal to 0.05mV/h or the appearance of the battery cell is good and has no abnormity, the aluminum-plastic film is complete and the battery cell is good in insulation; if K is more than 0.05mV/h or the phenomena of liquid leakage, breakdown or smoking occur at the edge sealing of the soft package lithium ion battery, the inside of the battery cell is corroded, and the aluminum plastic film is damaged.
Example 9:
as shown in fig. 1 and 2, an identification method for rapidly judging soft package lithium ion battery aluminum plastic film damage includes the following steps:
s1, welding: after the battery cell is packaged, laser welding is carried out on the positive electrode lug and the aluminum plastic film, and the power density of the laser welding is within the range of 3 multiplied by 105W/cm2The outer protective layer and the inner heat-sealing layer of the aluminum-plastic film are broken down through laser to expose the middle aluminum layer, so that the positive electrode tab is in welding contact with the middle aluminum layer of the aluminum-plastic film;
s2, sealing: after welding, dripping conductive silver oil at the welding position of the battery cell, isolating the welding position of the positive electrode lug from air, sealing, and conducting the positive electrode lug and the aluminum layer to play a role in conducting electricity;
s3, testing: performing OCV test on the battery cell processed in the step S2, respectively connecting a positive electrode tab and a negative electrode tab of the soft package lithium ion battery with two electrodes of a universal meter through a lead, measuring voltage OCV between the positive electrode and the negative electrode at a direct current voltage gear, and measuring the voltage OCV at time t1OCV measurement1Time t2OCV measurement2Voltage drop K ═ OCV (OCV)1-OCV2)/(t2-t1) Wherein t is2-t1＝32h；
S4, judgment: checking whether the voltage drop K of the battery cell exceeds a normal range, and if the voltage drop K is less than or equal to 0.05mV/h, indicating that the aluminum-plastic film is complete and the battery cell is well insulated; and if K is more than 0.05mV/h, the inside of the battery cell is corroded, and the aluminum-plastic film is damaged.
Example 10:
as shown in fig. 1 and 2, an identification method for rapidly judging soft package lithium ion battery aluminum plastic film damage includes the following steps:
s1, welding: after the battery cell is packaged, laser welding is carried out on the positive electrode lug and the aluminum plastic film, and the power density of the laser welding is within the range of 6 multiplied by 105W/cm2The outer protective layer and the inner heat-sealing layer of the aluminum-plastic film are broken down through laser to expose the middle aluminum layer, so that the positive electrode tab is in welding contact with the middle aluminum layer of the aluminum-plastic film;
s2, sealing: after welding, dripping conductive silver and copper oil at the welding position of the battery cell to isolate the welding position of the positive electrode lug from air for sealing, and simultaneously conducting the positive electrode lug and the aluminum layer to play a role in conducting electricity;
s3, testing: performing OCV test on the battery cell processed in the step S2, respectively connecting a positive electrode tab and a negative electrode tab of the soft package lithium ion battery with two electrodes of a universal meter through a lead, measuring voltage OCV between the positive electrode and the negative electrode at a direct current voltage gear, and measuring the voltage OCV at time t1OCV measurement1Time t2OCV measurement2Voltage drop K ═ OCV (OCV)1-OCV2)/(t2-t1) Wherein t is2-t1＝48h；
S4, judgment: checking whether the voltage drop K of the battery cell exceeds a normal range, and checking whether the appearance of the battery cell is abnormal; if K is less than or equal to 0.05mV/h or the appearance of the battery cell is good and has no abnormity, the aluminum-plastic film is complete and the battery cell is good in insulation; if K is more than 0.05mV/h or the phenomena of liquid leakage, breakdown or smoking occur at the edge sealing of the soft package lithium ion battery, the inside of the battery cell is corroded, and the aluminum plastic film is damaged.
The method mainly comprises the steps of breaking down a nylon layer and a PP layer of an aluminum-plastic film through laser to expose a middle aluminum layer, connecting a positive electrode lug with the aluminum layer of the middle layer of the aluminum-plastic film, and causing micro short circuit inside a battery cell if the aluminum-plastic film is damaged, so that current passes through heat-sealing abnormal areas, the internal resistance of the battery is increased, the voltage is reduced to exceed a specified measurement range, and the condition of the yield of the battery cell is rapidly detected.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.
Claims (10)
1. An identification method for rapidly judging the damage of an aluminum plastic film of a soft package lithium ion battery is characterized by comprising the following steps:
s1, welding: after the battery cell is packaged, welding a positive electrode lug and an aluminum-plastic film to enable the positive electrode lug to be in contact with a middle aluminum layer of the aluminum-plastic film;
s2, sealing: sealing the welding position of the battery cell after welding is finished;
s3, testing: performing a current test or an OCV test on the battery cell processed in step S2;
s4, judgment: checking whether the current or the voltage drop of the battery cell exceeds a normal range, and checking whether the appearance of the battery cell is abnormal; if the current appears, or the voltage drop exceeds the normal range, or the appearance of the battery cell is abnormal, the inside of the battery cell is corroded, and the aluminum-plastic film is damaged.
2. The method for rapidly identifying the soft package lithium ion battery aluminum plastic film damage according to claim 1, wherein in step S1, the outer protection layer and the inner heat seal layer of the aluminum plastic film are broken through welding to expose the middle aluminum layer, and then the positive electrode tab is in welding contact with the middle aluminum layer of the aluminum plastic film.
3. The method for rapidly identifying soft package lithium ion battery aluminum plastic film damage according to claim 1, wherein the welding in step S1 is laser welding.
4. The identification method for rapidly judging the soft package lithium ion battery aluminum plastic film damage according to claim 3, wherein the power density of the laser welding is within the range of 104～106W/cm2。
5. The method for rapidly identifying the soft package lithium ion battery aluminum plastic film damage according to claim 1, wherein in step S2, the sealing process is performed by dropping conductive oil onto the cell welding spot.
6. The identification method for rapidly judging the soft package lithium ion battery aluminum plastic film damage according to claim 5, wherein the conductive oil is conductive silver oil, conductive copper oil, conductive nickel oil or conductive silver copper oil.
7. The identification method for rapidly judging the soft package lithium ion battery aluminum plastic film damage according to claim 1, wherein the OCV test in step S3 specifically comprises: respectively connecting the positive electrode tab and the negative electrode tab of the soft package lithium ion battery with two electrodes of a voltage testing device through leads, measuring the voltage OCV between the positive electrode and the negative electrode, and measuring the voltage OCV at time t1OCV measurement1Time t2OCV measurement2Voltage drop K ═ OCV (OCV)1-OCV2)/(t2-t1)。
8. The method for rapidly identifying the soft package lithium ion battery aluminum plastic film damage according to claim 7, wherein the step S4 is specifically performed by the step of determining that the voltage drop of the battery cell exceeds a normal range: the voltage drop K of two voltage tests is more than 0.05 mV/h.
9. The method for rapidly identifying the soft package lithium ion battery aluminum plastic film damage according to claim 1, wherein the current test in step S3 specifically comprises: and respectively connecting the positive electrode lug and the negative electrode lug of the soft package lithium ion battery with two electrodes of a current testing device through leads, and measuring the current between the positive electrode and the negative electrode.
10. The method for rapidly judging the breakage of the aluminum-plastic film of the soft package lithium ion battery according to claim 1, wherein the step S4 of determining the appearance abnormality of the battery cell specifically comprises: the edge sealing of the soft package lithium ion battery has the phenomena of liquid leakage, breakdown or smoking.
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