Method for detecting and analyzing cause of battery voltage abnormality and method for solving voltage abnormality

Abstract

The invention discloses a method for detecting and analyzing reasons of battery voltage abnormity and a method for solving the voltage abnormity. The detection and analysis method comprises the following steps: acquiring a voltage detection map of a battery in an abnormal state in a charging and discharging process; the abnormal state comprises a first state or a second state; for the first state, after the reasons of the pole piece abnormity, the test instrument abnormity and the battery assembly abnormity are eliminated, determining that the voltage abnormity reason corresponding to the first state is the abnormity of the connection part of the instrument and the battery; and for the second state, after the reasons of pole piece abnormity and / or diaphragm rupture are eliminated, determining that the voltage abnormity reason corresponding to the second state is that the pole piece has burrs. According to the detection and analysis method, the abnormal reasons can be checked only according to the battery voltage abnormal curve graph, the process is simple and convenient, the detection result is accurate, and the checking efficiency of the abnormal reasons is improved.

Description

Technical Field

[0001] The invention relates to a method for detecting and analyzing the cause of abnormal battery voltage and a solution to the abnormal voltage. Background Art

[0002] In the field of battery technology, especially in the application of lithium-ion batteries, ensuring the performance and safety of batteries is crucial. The change of battery voltage can reflect the internal state of the battery and its working performance. Therefore, accurate monitoring of battery voltage is very important to ensure the safety and reliability of the battery.

[0003] In actual applications, batteries may have abnormal voltage due to a variety of reasons, which not only affects the normal operation of the battery, but also may bring safety hazards. Traditional detection and analysis methods include disassembly analysis and the use of specific detection devices. However, the disassembly analysis method not only fails to provide accurate fault diagnosis, but also causes irreversible damage to the battery, limiting its effectiveness in actual applications; specific detection devices require additional investment, which limits the progress of normal operation.

[0004] In view of the above problems, there is an urgent need for a more efficient and accurate method to detect and analyze the causes of abnormal battery voltage, so as to avoid the problems caused by traditional analysis methods and improve the accuracy of fault diagnosis. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defect of the prior art that there is a lack of efficient and accurate detection and analysis methods for the causes of abnormal battery voltage, and to provide a detection and analysis method for the causes of abnormal battery voltage and a solution to voltage abnormality. The detection and analysis method of the present invention can troubleshoot the causes of abnormality only based on the battery voltage abnormality curve graph. The process is simple and convenient, and the detection results are accurate, which improves the efficiency of troubleshooting the causes of abnormality. Furthermore, the present invention also provides a solution to battery voltage abnormality, which is easy to implement.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The present invention provides a method for detecting and analyzing the cause of abnormal battery voltage, which comprises the following steps:

[0008] Acquire a voltage detection diagram of a battery in an abnormal state during a charge and discharge process; the abnormal state includes a first state or a second state;

[0009] The first state includes:

[0010] Case ① The voltage changes in a wave-like manner: During the test, the voltage decreases from 1.5-3V to -0.5-1.5V at a rate of 0.5-19V / min, and then increases to 1.5-3V at a rate of 0.3-2.9V / 10min, for n cycles, where n≥1;

[0011] Case ② The voltage changes vertically: During the test, the voltage decreases from 1-2V to -1.0-0.5V within 0-1s; or increases from -1.0-0.5V to 1-2V within 0-1s;

[0012] Case ③ The voltage rebounds at the end of the step: During the test, the voltage at the end of the step increases by ≥0.3V within 0-10h;

[0013] The second state includes a voltage of 0;

[0014] For the first state, after excluding the causes of abnormality of the electrode piece, abnormality of the test instrument and abnormality of the battery assembly, it is determined that the cause of the voltage abnormality corresponding to the first state is the abnormality of the connection between the instrument and the battery;

[0015] With respect to the second state, after eliminating the causes of the pole piece abnormality and / or the diaphragm rupture, it is determined that the cause of the voltage abnormality corresponding to the second state is the presence of burrs on the pole piece.

[0016] In a preferred embodiment, in case ①, the voltage changes in a wave-like manner: during the test, the voltage drops from 1.7V to 1.39V within 1s, then increases to 1.706V within 10min, then drops from 1.706V to 0V within 3min, and then increases to 1.59V within 10min.

[0017] In a preferred embodiment, in case ②, the voltage changes vertically: during the test, the voltage decreases from 1.5V to -0.9V within 0-1s, and then increases from -0.9V to 1.1V within 0-1s.

[0018] In a preferred embodiment, in case ③, the voltage rebounds at the end of the step: during the test, the voltage at the end of the step increases by 0.4V at 30min and by 0.3V at 50min.

[0019] A process step is a specific procedure in the battery test process, and common process steps include static, constant current charging, constant voltage charging, constant current discharging, etc. In the present invention, during the test process, under normal conditions, the slope and platform sections of the curve are relatively smooth, and at the end of the process step (the shape is a convex part), the rebound potential caused by polarization is not higher than 0.075V, generally not higher than 0.06V, and the voltage rebound situation of situation ③ will not occur.

[0020] In the present invention, preferably, for the first state or the second state, the method of eliminating the abnormality of the electrode piece is: testing the retained electrode pieces produced in the same batch, and the voltage detection diagram shows a normal state.

[0021] In the present invention, preferably, for the first state, the method of eliminating the abnormality of the test instrument includes one or more of the following:

[0022] (1) Computer configuration: When a computer with higher configuration is replaced, the voltage detection diagram is still in the first state;

[0023] (2) Instrument calibration: The voltage error of the instrument should be within one ten-thousandth of one percent;

[0024] (3) Instrument line connection: Change the multi-line connection to a single-line connection, and the voltage detection diagram remains in the first state.

[0025] The single-line connection may include maintaining a single test cabinet connected to only a single socket and / or a single computer connected to only a single test cabinet.

[0026] In the present invention, preferably, for the first state, the causes of abnormality of the electrode and abnormality of the testing instrument are eliminated first, and then the causes of abnormality of the battery assembly are eliminated.

[0027] Preferably, the method of eliminating the battery assembly abnormality is: replacing the channel of the electrochemical workstation, and the voltage detection diagram shows a normal state.

[0028] In the present invention, preferably, for the second state, the method of eliminating the diaphragm rupture is: no diaphragm rupture can be observed through optical microscopy.

[0029] In the present invention, preferably, the battery is a half-battery.

[0030] In a preferred embodiment, the preparation method of the half-cell includes sequentially adding nickel foam, lithium sheet, electrolyte, diaphragm, electrolyte and artificial graphite electrode to the negative electrode steel shell, and then placing a positive electrode steel shell for sealing.

[0031] The present invention also provides a solution to abnormal battery voltage, which includes the following steps:

[0032] Determine the cause of abnormal battery voltage according to the above detection and analysis method;

[0033] If the voltage abnormality is caused by an abnormality in the connection between the instrument and the battery, the solution is to replace the electrochemical workstation channel or repair the original electrochemical workstation channel. The repair of the original electrochemical workstation channel is solved by one or more of the following methods:

[0034] (1) Replace the data cable connecting the fixture and the instrument;

[0035] (2) Increase the clamping force and / or increase the conductivity of the clamp;

[0036] (3) Clean the fixture;

[0037] If the voltage abnormality is caused by burrs on the electrode, the following solution is adopted:

[0038] Place the electrode on the sheet, and after die-cutting the electrode, place another layer of sheet on the electrode for secondary die-cutting.

[0039] In the present invention, preferably, the increasing of the clamping force of the clamp and / or the increasing of the conductivity of the clamp is achieved by placing nickel foam between the conductive nail and the battery.

[0040] In the present invention, preferably, the cleaning fixture comprises the following steps: placing an acid-containing cotton cloth on a conductive nail and contacting it at 40-60° C. for 1-5 hours.

[0041] Wherein, preferably, the acid is a mixture of nitric acid and sulfuric acid.

[0042] In the present invention, preferably, the secondary die-cutting pressure is 0.5-1.5 MPa, such as 1.1 MPa.

[0043] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0044] The reagents and raw materials used in the present invention are commercially available.

[0045] The positive and progressive effects of the present invention are:

[0046] The detection and analysis method of the present invention can troubleshoot the abnormal cause only based on the abnormal battery voltage curve, and the process is simple and convenient, and the detection result is accurate, which improves the efficiency of troubleshooting the abnormal cause. Furthermore, the present invention also provides a solution to the abnormal battery voltage, which is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a voltage detection diagram obtained in Example 1 when the battery is in an abnormal state during the charge and discharge process.

[0048] Figure 2 This is a voltage detection diagram obtained in Example 2 when the battery is in an abnormal state during the charge and discharge process.

[0049] Figure 3 This is a voltage detection diagram obtained in Example 3 when the battery is in an abnormal state during the charge and discharge process.

[0050] Figure 4This is a voltage detection diagram obtained in Example 6 when the battery is in an abnormal state during the charge and discharge process.

[0051] Figure 5 This is a voltage detection diagram of the normal state after being treated in Example 4. DETAILED DESCRIPTION

[0052] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0053] (1) Steps for making a half-cell:

[0054] Put 0.5g conductive carbon black (SP) and 23.5g artificial graphite into a 150ml stirring tank, cool and stir at a speed of 1500r / min for 1 minute, then add 25g CMC glue with a mass fraction of 1.5%, and adjust the speed to 2000r / min for 10 minutes; then add SBR binder with a solid content of 50%, continue to mix at a speed of 1500r / min for 3 minutes, then add 7g water, and continue to mix at the same speed for 3 minutes. After coating with a coater with a comma knife height set to 150μm, bake at 80°C for 6 hours. The compaction density of the control electrode is 1.5g / cm 3 The pole pieces are die-cut using a pneumatic die-cutting machine. The die-cutting die is a sponge knife die with six holes (there are 6 round holes on the die, and six round pieces can be die-cut at one time). The diameter of each pole piece is 16mm, and the quality deviation of the pole piece is controlled within 0.3mg.

[0055] The processed pole pieces are transferred to the glove box for battery assembly. The auxiliary materials used are as follows: lithium sheet: diameter 19mm, thickness 1.1mm; diaphragm: diameter 24mm, thickness 20μm; nickel foam: diameter 20mm, thickness 1.7mm; positive electrode steel shell: outer diameter 24mm, height 30mm. The battery assembly order is: the negative electrode steel shell is placed at the bottom, and the nickel foam, lithium sheet, 30μL electrolyte, diaphragm, 30μL electrolyte, artificial graphite pole piece are added in turn, and then the positive electrode steel shell is placed to seal.

[0056] (2) The half-cell test procedure is:

[0057] DC: 0.1C→5mV;

[0058] Rest: 10min;

[0059] DC: 0.05C → 5mV;

[0060] Rest: 10min;

[0061] DC: 0.01C→5mV;

[0062] Rest: 10min;

[0063] CC: 0.1C→2V.

[0064] The test equipment is the Blue Power CT3002 multi-channel electrochemical test cabinet.

[0065] Example 1

[0066] Take battery 1 and obtain its voltage detection diagram in an abnormal state during the charging and discharging process, such as Figure 1 As shown; Figure 1 Case ① The voltage changes in a wave-like manner: During the test, the voltage drops from 1.7V to 1.39V within 1s, then rises to 1.706V within 10min, drops from 1.706V to 0V within 3min, and then rises to 1.59V within 10min, which belongs to the first state. The steps of the detection and analysis method for the cause of the abnormal voltage of battery 1 are as follows:

[0067] (1) Eliminate the cause of the abnormality of the electrode:

[0068] The sample electrodes produced in the same batch were die-cut and assembled into batteries in the same way. The batteries were retested and the voltage detection graph showed no obvious change and remained in the first state.

[0069] (2) Further eliminate the causes of test instrument abnormalities:

[0070] a. Computer configuration: Replace a computer with a higher configuration and connect it to the test cabinet; the voltage detection diagram is still in the first state;

[0071] b. Instrument calibration: The voltage error of the instrument calibration is within one ten-thousandth;

[0072] c. Instrument line connection: replace the multi-line connection with a single-line connection. Specifically, keep a single test cabinet connected to only a single socket, and a single computer connected to only a single test cabinet. The voltage detection diagram remains in the first state.

[0073] (3) Further eliminate the causes of abnormalities in the battery assembly process:

[0074] After changing the channel of the electrochemical workstation, the voltage detection graph returned to normal.

[0075] (4) The cause of the voltage abnormality was determined to be an abnormality in the connection between the instrument and the battery.

[0076] Example 2

[0077] Take battery 2 and obtain its voltage detection diagram in an abnormal state during the charging and discharging process, such as Figure 2 As shown; Figure 2 For situation ②, the voltage changes vertically: during the test, the voltage drops from 1.5V to -0.9V within 0-1s, and then increases from -0.9V to 1.1V within 0-1s, which belongs to the first state. The steps of the detection and analysis method for the cause of the abnormal voltage of battery 2 are as follows:

[0078] (1) Eliminate the cause of the abnormality of the electrode:

[0079] The sample electrodes produced in the same batch were die-cut and assembled into batteries in the same way. The batteries were retested and the voltage detection graph showed no obvious change and remained in the first state.

[0080] (2) Further eliminate the causes of test instrument abnormalities:

[0081] a. Computer configuration: Replace a computer with a higher configuration and connect it to the test cabinet; the voltage detection diagram is still in the first state;

[0082] b. Instrument calibration: The voltage error of the instrument calibration is within one ten-thousandth;

[0083] c. Instrument line connection: replace the multi-line connection with a single-line connection. Specifically, keep a single test cabinet connected to only a single socket, and a single computer connected to only a single test cabinet. The voltage detection diagram remains in the first state.

[0084] (3) Further eliminate the causes of abnormalities in the battery assembly process:

[0085] After changing the channel of the electrochemical workstation, the voltage detection graph returned to normal.

[0086] (4) The cause of the voltage abnormality was determined to be an abnormality in the connection between the instrument and the battery.

[0087] Example 3

[0088] Take battery 3 and obtain its voltage detection diagram in an abnormal state during the charging and discharging process, such as Figure 3 As shown; Figure 3 For situation ③, the voltage rebounds at the end of the process step: During the test, the voltage at the end of the process step increases by 0.4V at 30min and 0.3V at 50min, which belongs to the first state. The steps of the detection and analysis method for the cause of the abnormal voltage of battery 3 are as follows:

[0089] (1) Eliminate the cause of the abnormality of the electrode:

[0090] The sample electrodes produced in the same batch were die-cut and assembled into batteries in the same way. The batteries were retested and the voltage detection graph showed no obvious change and remained in the first state.

[0091] (2) Further eliminate the causes of test instrument abnormalities:

[0092] a. Computer configuration: Replace a computer with a higher configuration and connect it to the test cabinet; the voltage detection diagram is still in the first state;

[0093] b. Instrument calibration: The voltage error of the instrument calibration is within one ten-thousandth;

[0094] c. Instrument line connection: replace the multi-line connection with a single-line connection. Specifically, keep a single test cabinet connected to only a single socket, and a single computer connected to only a single test cabinet. The voltage detection diagram remains in the first state.

[0095] (3) Further eliminate the causes of abnormalities in the battery assembly process:

[0096] After changing the channel of the electrochemical workstation, the voltage detection graph returned to normal.

[0097] (4) The cause of the voltage abnormality was determined to be an abnormality in the connection between the instrument and the battery.

[0098] Example 4

[0099] Take 60 batteries that are determined to have abnormal battery voltage due to abnormal connection between the instrument and the battery, and take the following treatment methods: replace the channel of the electrochemical workstation;

[0100] 100% of the abnormal situation returns to normal, and the voltage detection diagram is as follows Figure 5 shown.

[0101] Example 5

[0102] Take 60 batteries that are determined to have abnormal battery voltage due to abnormal connection between the instrument and the battery, and take the following treatment methods: Repair the original electrochemical workstation channel:

[0103] (1) Replace the data cable connecting the fixture and the instrument;

[0104] 1% of abnormal situations return to normal.

[0105] (2) Increase the clamping force and / or increase the conductivity of the clamp: Place nickel foam between the conductive nail and the battery steel shell. The size of the nickel foam is 21mm*1mm.

[0106] 36% of abnormal situations returned to normal.

[0107] (3) Cleaning the fixture: Place the conductive nails in the foam board with the surface in contact with the battery facing up. In a fume hood, soak cotton cloth in a 10% nitric acid and sulfuric acid solution with a ratio of 1:1. Spread the cloth on the conductive nails and seal it with a waterproof cloth. Place the conductive nails in a high temperature environment at 50°C for 3 hours. After taking out the conductive nails, wash them with pure water, then with ethanol, and finally dry them at 60°C for 10 hours.

[0108] The remaining 63% of abnormal situations returned to normal.

[0109] Example 6

[0110] Take battery 4 and obtain its voltage detection diagram in an abnormal state during the charging and discharging process, such as Figure 4 As shown; Figure 4 The voltage is 0, which belongs to the first state. The steps of the detection and analysis method for the abnormal voltage of the battery 4 are as follows:

[0111] (1) Eliminate the cause of the abnormality of the electrode:

[0112] The sample electrodes produced in the same batch were die-cut and assembled into batteries in the same way. The batteries were retested and the voltage detection graph showed no obvious change and remained in the first state.

[0113] (2) Eliminate the cause of diaphragm rupture: No diaphragm rupture was observed under optical microscopy.

[0114] (3) It was determined that the cause of the voltage abnormality was the presence of burrs on the electrode.

[0115] Example 7

[0116] For the battery 4 in Example 6 where the abnormal battery voltage is determined to be caused by burrs on the electrode, the following processing method is adopted:

[0117] Take the pole pieces produced in the same batch but not die-cut, adjust the die-cutting pressure of the pneumatic die-cutting machine to 0.5MPa, and place the pole pieces on a 250mm*100mm*2mm PP board during die-cutting. Place the pole pieces after die-cutting, and place a PP board of the same size on top of the pole pieces. Lay them flat from top to bottom, and apply 1MPa pressure on the sealing machine again to obtain 6 pole pieces. Assemble the battery in the same way.

[0118] After processing, the voltage detection diagrams of the 6 batteries returned to normal.

[0119] 100% of the abnormal situations were restored to normal, which verified that the cause of the voltage abnormality in Example 6 was the presence of burrs on the electrode.

Claims

1. A method for detecting and analyzing the cause of abnormal battery voltage, characterized in that: It includes the following steps: Acquire a voltage detection diagram of a battery in an abnormal state during a charge and discharge process; the abnormal state includes a first state or a second state; The first state includes: Case ① The voltage changes in a wave-like manner: During the test, the voltage drops from 1.5-3V to -0.5-1.5V within 3 minutes, and then rises to 1.5-3V within 10 minutes, and the cycle repeats n times, n≥1; Case ② The voltage changes vertically: During the test, the voltage decreases from 1-2V to -1.0-0.5V within 0-1s; or increases from -1.0-0.5V to 1-2V within 0-1s; Case ③ The voltage rebounds at the end of the step: During the test, the voltage at the end of the step increases by ≥0.3V within 0-10h; The second state includes a voltage of 0; For the first state, after excluding the causes of abnormality of the electrode piece, abnormality of the test instrument and abnormality of the battery assembly, it is determined that the cause of the voltage abnormality corresponding to the first state is the abnormality of the connection between the instrument and the battery; With respect to the second state, after eliminating the causes of the pole piece abnormality and / or the diaphragm rupture, it is determined that the cause of the voltage abnormality corresponding to the second state is the presence of burrs on the pole piece.

2. The method for detecting and analyzing the cause of abnormal battery voltage according to claim 1, characterized in that: For the first state or the second state, the method of eliminating the abnormality of the electrode piece is: testing the retained electrode pieces produced in the same batch, and the voltage detection diagram shows a normal state.

3. The method for detecting and analyzing the cause of abnormal battery voltage according to claim 1, characterized in that: For the first state, the method of eliminating the abnormality of the test instrument includes one or more of the following: (1) Computer configuration: When a computer with higher configuration is replaced, the voltage detection diagram is still in the first state; (2) Instrument calibration: The voltage error of the instrument should be within one ten-thousandth of one percent; (3) Instrument line connection: Change the multi-line connection to a single-line connection, and the voltage detection diagram remains in the first state.

4. The method for detecting and analyzing the cause of abnormal battery voltage according to claim 1, characterized in that: For the first state, first eliminate the causes of abnormal electrode and test instrument, and then eliminate the causes of abnormal battery assembly; the method of eliminating the abnormal battery assembly is preferably: replace the channel of the electrochemical workstation, and the voltage detection diagram shows a normal state.

5. The method for detecting and analyzing the cause of abnormal battery voltage according to claim 1, characterized in that: For the second state, the method of excluding the rupture of the diaphragm is: no rupture of the diaphragm can be observed through optical microscopy.

6. The method for detecting and analyzing the cause of abnormal battery voltage according to claim 1, characterized in that: The battery is a half-cell.

7. A solution to abnormal battery voltage, characterized in that: It includes the following steps: Determine the cause of abnormal battery voltage according to the detection and analysis method described in any one of claims 1 to 6; If the voltage abnormality is caused by an abnormality in the connection between the instrument and the battery, the solution is to replace the electrochemical workstation channel or repair the original electrochemical workstation channel. The repair of the original electrochemical workstation channel is solved by one or more of the following methods: (1) Replace the data cable connecting the fixture and the instrument; (2) Increase the clamping force and / or increase the conductivity of the clamp; (3) Clean the fixture; If the voltage abnormality is caused by burrs on the electrode, the following solution is adopted: Place the electrode on the sheet, and after die-cutting the electrode, place another layer of sheet on the electrode for secondary die-cutting.

8. The solution to abnormal battery voltage as claimed in claim 7, characterized in that: The increasing of the clamping force and / or the increasing of the conductivity of the clamp is achieved by placing nickel foam between the conductive nail and the battery.

9. The solution to abnormal battery voltage as claimed in claim 8, characterized in that: The cleaning fixture comprises the following steps: placing an acid-containing cotton cloth on a conductive nail and contacting it at 40-60° C. for 1-5 hours; preferably, the acid is a mixture of nitric acid and sulfuric acid.

10. The solution to abnormal battery voltage as claimed in claim 7, characterized in that: The secondary die-cutting pressure is 0.5-1.5 MPa, for example 1.1 MPa.

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