Formation process of soft package lithium battery

Abstract

The invention relates to the technical field of production of soft package lithium batteries, in particular to a formation process of a soft package lithium battery, which comprises the following steps: A, performing pre-treatment on the soft package lithium battery to form a compact sei film, and performing exhaust treatment on the soft package lithium battery in and / or after the pre-treatment process; b, n times of formation treatment are carried out on the soft package lithium battery, the formation temperature is Tn, and the formation current is In; the formation temperature Tn and the formation current In are both increased along with the increase of n; c, performing aging treatment on the soft package lithium battery, and monitoring voltage change and appearance change of the soft package lithium battery at the same time; and D, sorting the soft package lithium batteries. According to the method, the soft package lithium battery is pre-formed by adopting low-temperature small current, so that the soft package lithium battery generates a compact sei film to be protected, and during subsequent formation, a sectional formation mode is adopted to generate sei films with different densities to improve the conductivity, so that the method has two advantages at the same time, and the quality of the soft package lithium battery is improved.

Description

Technical Field

[0001] The invention relates to the technical field of soft-pack lithium battery production, in particular to a formation process of a soft-pack lithium battery. Background Art

[0002] The formation process is one of the most important processes in the production of soft-pack lithium batteries. Its purpose is to activate the electrolyte of soft-pack lithium batteries and allow soft-pack lithium batteries to form sei films. In the existing formation process, the following contradictions are often encountered: if high temperature and high current are used for pre-formation and formation, although the rate of forming sei films is fast, the density of sei films is low, which does not play a protective role but can improve ion conductivity (cited from: Yang Juan, the influence of lithium-ion battery formation conditions on formation effects); if low temperature and low current are used for pre-formation and formation, the density of the sei films generated is high, but it takes a long time. Summary of the invention

[0003] In view of the problems of the prior art, the present invention provides a formation process for a soft-pack lithium battery, which can combine the above two contradictions to generate a dense and loose sei film.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a formation process for a soft-pack lithium battery, comprising the following steps:

[0006] A. pre-treatment of the soft-pack lithium battery to form a dense sei film, and exhaust treatment of the soft-pack lithium battery during and / or after the pre-treatment process;

[0007] B. Perform n formation treatments on the soft-pack lithium battery at a formation temperature of T n , the formation current is I n ; Where n is a natural number and 2≤n≤6, the formation temperature T n The unit is ℃, the formation current I n The unit is mA, the formation temperature is T n , the formation current In increases with the increase of n;

[0008] C. Perform aging treatment on soft-pack lithium batteries and monitor the voltage and appearance changes of soft-pack lithium batteries;

[0009] D. Sort and process soft-pack lithium batteries.

[0010] Furthermore, step A specifically includes:

[0011] A1. Perform a vacuum treatment on the soft-pack lithium battery;

[0012] A2. Charge the soft-pack lithium battery and sense the pressure change inside the soft-pack lithium battery; if the pressure inside the soft-pack lithium battery exceeds the threshold, execute step A3, otherwise execute step A4;

[0013] A3. Perform secondary degassing on the soft-pack lithium battery, and then proceed to step A4;

[0014] A4. Sense the pressure change rate of the soft-pack lithium battery. If the pressure change rate is less than the preset value, vacuum the soft-pack lithium battery.

[0015] A5. Keep charging the soft-pack lithium battery until the preset time is reached.

[0016] Furthermore, a pre-chemical device for performing step A is provided, the pre-chemical device comprising a vacuum pump, a filter, a switch valve, an air pressure sensor, a charging module and a temperature control module, the vacuum pump is connected to the soft-pack lithium battery through the filter and the switch valve, the air pressure sensor is used to be inserted into the soft-pack lithium battery and sense the air pressure, the charging module is used to charge the soft-pack lithium battery, and the temperature control module is used to control the temperature of the soft-pack lithium battery;

[0017] In step A2, it also includes sensing the rate of change of air pressure in the soft-pack lithium battery. If the rate of change of air pressure is greater than a preset value, the soft-pack lithium battery is cooled by a temperature control module;

[0018] If the air pressure change rate of the soft-pack lithium battery does not exceed the lower threshold within a specific time, the temperature of the soft-pack lithium battery is increased through the temperature control module;

[0019] In step A5, it specifically includes:

[0020] Performing a cooling process on the soft-pack lithium battery so that the temperature of the soft-pack lithium battery is reduced to T';

[0021] The temperature of the soft-pack lithium battery is maintained at T', and then the soft-pack lithium battery is continuously charged until a preset time is reached.

[0022] Furthermore, the pre-chemical device also includes a weighing module and a liquid replenishing module, the switch valve has a first input port, a second input port and an output port, the first input port is connected to the filter, the second input port is connected to the liquid replenishing module, and the output port is used to connect to the soft-pack lithium battery;

[0023] Step A also includes:

[0024] A6. Weigh the weight change of the soft-pack lithium battery using the weighing module;

[0025] A7. Control the switch valve to switch to connect the second input port with the output port;

[0026] A8. The refilling module refills the electrolyte of the soft-pack lithium battery until the weight of the soft-pack lithium battery returns to the weight before pre-treatment;

[0027] A9.Discharge the soft-pack lithium battery.

[0028] Further, step B specifically includes:

[0029] B1. Heat the temperature of the soft-pack lithium battery to T n ; T n = k'*n, k' is a constant and the value range of k' is 15-20;

[0030] B2. For soft pack lithium battery, the current value is I n Charge until the current charge of the soft-pack lithium battery becomes 100% of the total charge. Among them I n =n*I, I is the preset rated current value;

[0031] B3. Repeat steps B1 and B2 for n times;

[0032] Among them, k=1+2+…+n.

[0033] Furthermore, when n>1, step B1 is executed, and I is maintained. n-1 The current value is used to charge the soft-pack lithium battery, and the temperature of the soft-pack lithium battery is increased until the temperature of the soft-pack lithium battery increases from T n-1 Heating to T n Then, increase the current value to I n .

[0034] Furthermore, a formation device for performing step B is provided, comprising an exhaust module, a temperature adjustment module, a power supply module and a sealing module,

[0035] The exhaust module is used to communicate with the inside of the soft-pack lithium battery and exhaust the soft-pack lithium battery so that a negative pressure is formed inside the soft-pack lithium battery;

[0036] The temperature control module is used to adjust the temperature of the soft-pack lithium battery;

[0037] The power supply module is used to charge the soft-pack lithium battery;

[0038] The sealing module is used to seal soft-pack lithium batteries.

[0039] Furthermore, the sealing module is used to seal the soft-pack lithium battery, specifically including:

[0040] Clamp the tube of the soft-pack lithium battery;

[0041] Cutting the tube of the soft-pack lithium battery to reduce the length of the tube;

[0042] Ultrasonic welding is performed on the tube of the soft-pack lithium battery to keep the tube closed;

[0043] The tube of the soft-pack lithium battery is sealed with glue to seal and cover the tube.

[0044] Further, step C specifically includes:

[0045] C1. Place the soft-pack lithium battery for aging and monitor the voltage change of the soft-pack lithium battery;

[0046] C2. Obtain the appearance changes of soft-pack lithium batteries during the aging process;

[0047] C3. Based on the appearance changes and voltage changes of the soft-pack lithium battery, infer the aging state of the soft-pack lithium battery and record it.

[0048] Furthermore, step D specifically includes:

[0049] D1. Obtain the voltage change of the soft-pack lithium battery. If the voltage change is within a preset range, the lithium battery is determined to be in the first state, otherwise it is determined to be in the second state;

[0050] D2. Obtain an image of the soft-pack lithium battery, and obtain the volume change of the soft-pack lithium battery and whether there are signs of damage from the image of the soft-pack lithium battery;

[0051] D3. Compare the volume change of the soft-pack lithium battery with the pre-stored data. If the volume change of the soft-pack lithium battery is within the preset range, the soft-pack lithium battery is determined to be in the third state, otherwise it is determined to be in the fourth state;

[0052] D4. Determine the damage length and depth by pixel traces in the image. If there is no damage trace, the soft-pack lithium battery is determined to be in the fifth state; if the damage length and depth are both within the preset range, the soft-pack lithium battery is determined to be in the sixth state; if the damage length and / or depth exceeds the preset range, the soft-pack lithium battery is determined to be in the seventh state;

[0053] D5. Sort the soft-pack lithium batteries as follows:

[0054] When the soft-pack lithium battery is in any one of the second state, the fourth state, and the seventh state, the soft-pack lithium battery is sorted to a non-conforming station;

[0055] Sorting the soft-pack lithium batteries in the first state, the third state, and the fifth state to the qualified stations;

[0056] The soft-pack lithium batteries that are in the first state, the third state, and the sixth state are sorted to the repair station.

[0057] Beneficial effects of the present invention: the present invention uses low temperature and low current to treat the soft-pack lithium battery in the pre-forming stage, so that the soft-pack lithium battery generates a dense sei film for protection. Subsequently, during the formation, a segmented formation method is adopted to generate sei films with different densities to improve the conductivity, so that the present invention has two advantages at the same time, thereby improving the quality of the soft-pack lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a flow chart of the present invention.

[0059] Figure 2 It is a schematic diagram of the pre-chemical device described in the present invention.

[0060] Figure 3 Schematic diagram of the formation device described in the present invention.

[0061] Reference numerals:

[0062] 1—pre-chemical device, 11—vacuum pump, 12—filter, 13—switch valve, 14—air pressure sensor, 15—charging module, 16—temperature control module, 17—weighing module, 18—liquid replenishing module; 2—forming device, 21—exhaust module, 22—temperature regulating module, 23—power supply module, 24—sealing module, 25—clamping and welding mechanism, 26—cutting mechanism, 27—sealing mechanism. DETAILED DESCRIPTION

[0063] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with the embodiments and drawings, and the contents mentioned in the embodiments are not intended to limit the present invention. The present invention is described in detail below in conjunction with the drawings.

[0064] like Figures 1 to 3 As shown, the present invention provides a formation process of a soft-pack lithium battery, comprising the following steps:

[0065] A. pre-treatment of the soft-pack lithium battery to form a dense sei film, and exhaust treatment of the soft-pack lithium battery during and / or after the pre-treatment process;

[0066] B. Perform n formation treatments on the soft-pack lithium battery at a formation temperature of T n , the formation current is I n ; Where n is a natural number and 2≤n≤6, the formation temperature T n The unit is ℃, the formation current I n The unit is mA, the formation temperature is T n , the formation current In increases with the increase of n;

[0067] C. Perform aging treatment on soft-pack lithium batteries and monitor the voltage and appearance changes of soft-pack lithium batteries;

[0068] D. Sort and process soft-pack lithium batteries.

[0069] That is, the present invention adopts a formation method of combining low temperature and small current with high temperature and large current. In the pre-forming stage, a low temperature and small current method is used to form a dense sei film. For example, the pre-forming is performed at room temperature or even lower temperature, and a charge and discharge current of 0.05C or even lower current is used to perform pre-forming, so that the density of the sei film formed under pre-forming and in contact with the two poles (mainly the cathode) is high, thereby preventing the electrolyte from reacting with the two poles and corroding the two poles during subsequent use; after the pre-forming is completed, a segmented formation process is used to treat the soft-pack lithium battery, that is, as the number of formations increases, the temperature and current are continuously increased, so that the soft-pack lithium battery has sei films of various densities on the basis of a dense sei film. This method can make the structure inside the dense sei film rough and loose, which is beneficial to improving the ionic conductivity, thereby allowing the soft-pack lithium battery to discharge stably and efficiently.

[0070] In this embodiment, step A specifically includes:

[0071] A1. Perform a vacuum treatment on the soft-pack lithium battery;

[0072] A2. Charge the soft-pack lithium battery and sense the pressure change inside the soft-pack lithium battery; if the pressure inside the soft-pack lithium battery exceeds the threshold, execute step A3, otherwise execute step A4;

[0073] A3. Perform secondary degassing on the soft-pack lithium battery, and then proceed to step A4;

[0074] A4. Sense the pressure change rate of the soft-pack lithium battery. If the pressure change rate is less than the preset value, vacuum the soft-pack lithium battery.

[0075] A5. Keep charging the soft-pack lithium battery until the preset time is reached.

[0076] That is, after the liquid injection is completed, the soft-pack lithium battery needs to be vacuumed so that the pre-forming is carried out under a negative pressure state, thereby effectively avoiding the influence and interference of oxygen on the pre-forming; during the pre-forming, the gas inside the electrolyte and the gas generated by the reaction will be released into the soft-pack lithium battery. Therefore, the present invention needs to monitor the air pressure change inside the soft-pack lithium battery at all times, and perform a secondary air pumping treatment when the air pressure reaches a certain value to avoid bulging or cracking of the soft-pack lithium battery; when the air pressure change of the soft-pack lithium battery is lower than a preset value (which can be determined by conventional multiple tests), it proves that the gas generation is basically completed. At this time, the soft-pack lithium battery is subjected to the final air pumping treatment in the pre-forming process, and then the pre-forming is continued until the preset pre-forming time is reached to ensure that the generated dense sei film is thick enough.

[0077] Specifically, the present invention provides a pre-chemical device 1 for performing step A, the pre-chemical device 1 comprising a vacuum pump 11, a filter 12, a switch valve 13, an air pressure sensor 14, a charging module 15 and a temperature control module 16, the vacuum pump 11 is connected to the soft-pack lithium battery through the filter 12 and the switch valve 13, the air pressure sensor 14 is used to be inserted into the soft-pack lithium battery and sense the air pressure, the charging module 15 is used to charge the soft-pack lithium battery, and the temperature control module 16 is used to control the temperature of the soft-pack lithium battery;

[0078] In step A2, it also includes sensing the rate of change of the air pressure in the soft-pack lithium battery. If the rate of change of the air pressure is greater than a preset value, the temperature of the soft-pack lithium battery is reduced by the temperature control module 16;

[0079] If the pressure change rate of the soft-pack lithium battery does not exceed the lower threshold within a specific time, the temperature control module 16 is used to increase the temperature of the soft-pack lithium battery;

[0080] In step A5, it specifically includes:

[0081] Performing a cooling process on the soft-pack lithium battery so that the temperature of the soft-pack lithium battery is reduced to T';

[0082] The temperature of the soft-pack lithium battery is maintained at T', and then the soft-pack lithium battery is continuously charged until a preset time is reached.

[0083] That is, the soft-pack lithium battery will inevitably generate heat during the pre-forming process. At this time, in order to ensure that the pre-forming effect meets the expectations, the temperature control module 16 is used to cool the soft-pack lithium battery. In order to ensure the efficiency of the pre-forming, when the temperature of the soft-pack lithium battery is too low, it is also necessary to heat it up to maintain the pre-forming within a preset temperature range.

[0084] The temperature control module 16 preferably includes a heating wire and a water cooling module. When the temperature needs to be increased, the temperature around the soft-pack lithium battery is increased by the heating wire. When the temperature needs to be reduced, the temperature around the soft-pack lithium battery is reduced by the water cooling module.

[0085] It should also be noted that the soft-pack lithium battery of the present invention has a tube inserted into the aluminum-plastic film, which is integrated with the aluminum-plastic film and is used for operations such as liquid injection, gas extraction, and liquid replenishment. In the pre-chemical device 1 of the present invention, the vacuum pump 11 is connected to the tube after passing through the filter 12 and the switch valve 13, that is, the extracted gas is filtered and absorbed by the filter 12 for impurities such as electrolyte, and then extracted to the outside by the vacuum pump 11, so as to ensure the safety of the vacuum pump 11 and avoid pollution to the environment.

[0086] Specifically, the pre-chemical device 1 further includes a weighing module 17 and a liquid replenishing module 18, the switch valve 13 has a first input port, a second input port and an output port, the first input port is connected to the filter 12, the second input port is connected to the liquid replenishing module 18, and the output port is used to connect to the soft-pack lithium battery;

[0087] Step A also includes:

[0088] A6. Weigh the weight change of the soft-pack lithium battery by weighing module 17;

[0089] A7. Control the switch valve 13 to switch to the second input port and the output port;

[0090] A8. The refill module 18 replenishes the electrolyte of the soft-pack lithium battery until the weight of the soft-pack lithium battery is restored to the weight before pre-treatment;

[0091] A9.Discharge the soft-pack lithium battery.

[0092] When vacuum is drawn, a portion of liquid will inevitably be drawn out, so the weight of the soft-pack lithium battery will change. In view of this, the present invention adopts a three-position three-way valve as the switch valve 13, so that the switch has three states: a sealed tube, a control tube connected to the vacuum pump 11, and a control injection module connected to the tube. After the pre-formation is completed, the weight of the soft-pack lithium battery is supplemented by replenishing the liquid according to the weight loss of the soft-pack lithium battery. The rule of replenishment is preferably that the mass of the replenished electrolyte is greater than the weight of the lost electrolyte: if 100g of weight is lost, 105-110g of electrolyte is supplemented, and the weight loss problem encountered during the subsequent formation is solved by the extra 5-10g of electrolyte, thereby avoiding the occurrence of secondary replenishment.

[0093] In this embodiment, step B specifically includes:

[0094] B1. Heat the temperature of the soft-pack lithium battery to T n ; T n= k'*n, k' is a constant and the value range of k' is 15-20;

[0095] B2. For soft pack lithium battery, the current value is I n Charge until the current charge of the soft-pack lithium battery becomes 100% of the total charge. Among them I n =n*I, I is the preset rated current value;

[0096] B3. Repeat steps B1 and B2 for n times;

[0097] Among them, k=1+2+…+n.

[0098] Taking the number of formations as four times as an example, k is equal to 1+2+3+4=10, the temperature of the first formation is 20°C, and the formation current is I;

[0099] When the current power of the soft-pack lithium battery becomes 1 / 10 of the total power, the second formation is performed. At this time, the formation temperature is 40°C and the formation current is 2I.

[0100] When the current power of the soft-pack lithium battery becomes 3 / 10 of the total power, the third formation is performed. At this time, the formation temperature is 60°C and the formation current is 3I;

[0101] When the current power of the soft-pack lithium battery becomes 6 / 10 of the total power, the fourth formation is performed, at which the formation temperature is 80°C and the formation current is 4I.

[0102] In the above manner, the soft-pack lithium battery produced by the present invention can form a loose and uneven sei membrane structure. Since the dense sei membrane formed by pre-forming realizes the protection of the cathode, the sei membrane structure formed subsequently is mainly used to ensure the conductivity at the cathode, so as to achieve the two effects of avoiding cathode corrosion as much as possible and improving conductivity.

[0103] Specifically, when n>1, step B1 is executed, and I is maintained. n-1 The current value is used to charge the soft-pack lithium battery, and the temperature of the soft-pack lithium battery is increased until the temperature of the soft-pack lithium battery increases from T n-1 Heating to T n Then, increase the current value to I n .

[0104] For example, in the second formation, the current I is maintained to charge and discharge the soft-pack lithium battery, and then the temperature is raised in this state until the temperature of the soft-pack lithium battery reaches 40°C, and then the current is increased to 2I. In this way, there is a transition between the two formations of the soft-pack lithium battery, avoiding the impact of the formation result caused by the one-time jump of the two parameters.

[0105] Specifically, the present invention provides a formation device 2 for performing step B, comprising an exhaust module 21, a temperature adjustment module 22, a power supply module 23 and a sealing module 24.

[0106] The exhaust module 21 is used to communicate with the inside of the soft-pack lithium battery and exhaust the soft-pack lithium battery so that a negative pressure is formed inside the soft-pack lithium battery;

[0107] The temperature adjustment module 22 is used to adjust the temperature of the soft-pack lithium battery;

[0108] The power supply module 23 is used to charge the soft-pack lithium battery;

[0109] The sealing module 24 is used to seal the soft-pack lithium battery.

[0110] In actual use, the sealing module 24 includes a clamping and welding mechanism 25, a shearing mechanism 26 and a sealing mechanism 27, wherein the clamping and welding mechanism 25 can adopt a structure in which the two output ends of the pneumatic fingers are respectively provided with ultrasonic welders, the shearing mechanism 26 is composed of a conventional cylinder or motor-driven scissors and a robot, and the sealing mechanism 27 is a conventional structure driven by a lifting module.

[0111] Based on the above-mentioned sealing module 24, the sealing module 24 is used to seal the soft-pack lithium battery, specifically including:

[0112] Clamp the tube of the soft-pack lithium battery;

[0113] Cutting the tube of the soft-pack lithium battery to reduce the length of the tube;

[0114] Ultrasonic welding is performed on the tube of the soft-pack lithium battery to keep the tube closed;

[0115] The tube of the soft-pack lithium battery is sealed with glue to seal and cover the tube.

[0116] During formation, gas may also be generated, but since most of the gas has been generated and drained in the pre-formation, the gas generated during formation is not much, and it only needs to be uniformly discharged after the formation step is completed; and after exhausting, the soft-pack lithium battery can be sealed. At this time, the method adopted by the present invention is: first clamp the tube of the soft-pack lithium battery to avoid leakage; then shorten the tube of the soft-pack lithium battery, preferably cut it to be flush with or slightly higher than the soft-pack lithium battery; then use the clamping welding mechanism 25 to perform ultrasonic welding to make the tube bonded and maintain the clamped state, and finally perform sealing treatment to fill the tube position, achieve secondary sealing and avoid the tube being exposed and affecting the aesthetic effect.

[0117] After the sealing process, the soft-pack lithium battery is transferred to the aging process.

[0118] In this embodiment, step C specifically includes:

[0119] C1. Place the soft-pack lithium battery for aging and monitor the voltage change of the soft-pack lithium battery;

[0120] C2. Obtain the appearance changes of soft-pack lithium batteries during the aging process;

[0121] C3. Based on the appearance changes and voltage changes of the soft-pack lithium battery, infer the aging state of the soft-pack lithium battery and record it.

[0122] That is, during the aging process, in addition to sensing the voltage change of the soft-pack lithium battery, it is also necessary to observe the appearance of the soft-pack lithium battery. Only when both the appearance and the voltage change meet the requirements, the soft-pack lithium battery is qualified.

[0123] Based on the above steps C1-C3, step D of the present invention specifically includes:

[0124] D1. Obtain the voltage change of the soft-pack lithium battery. If the voltage change is within a preset range, the lithium battery is determined to be in the first state, otherwise it is determined to be in the second state;

[0125] D2. Obtain an image of the soft-pack lithium battery, and obtain the volume change of the soft-pack lithium battery and whether there are signs of damage from the image of the soft-pack lithium battery;

[0126] D3. Compare the volume change of the soft-pack lithium battery with the pre-stored data. If the volume change of the soft-pack lithium battery is within the preset range, the soft-pack lithium battery is determined to be in the third state, otherwise it is determined to be in the fourth state;

[0127] D4. Determine the damage length and depth by pixel traces in the image. If there is no damage trace, the soft-pack lithium battery is determined to be in the fifth state; if the damage length and depth are both within the preset range, the soft-pack lithium battery is determined to be in the sixth state; if the damage length and / or depth exceeds the preset range, the soft-pack lithium battery is determined to be in the seventh state;

[0128] D5. Sort the soft-pack lithium batteries as follows:

[0129] When the soft-pack lithium battery is in any one of the second state, the fourth state, and the seventh state, the soft-pack lithium battery is sorted to a non-conforming station;

[0130] Sorting the soft-pack lithium batteries in the first state, the third state, and the fifth state to the qualified stations;

[0131] The soft-pack lithium batteries that are in the first state, the third state, and the sixth state are sorted to the repair station.

[0132] That is, when the voltage or volume of a soft-pack lithium battery changes abnormally, or there is a large damage on the surface, it proves that the soft-pack lithium battery has a safety hazard, such as being unable to charge stably, being prone to bulging or leaking. At this time, the soft-pack lithium battery is directly judged as a defective product and needs to be sorted to the defective station for subsequent scrapping;

[0133] When the voltage change of the soft-pack lithium battery is normal, the volume change is within the required value, and there is no trace on the surface, the soft-pack lithium battery is qualified and can be directly sorted for the next process;

[0134] If the voltage change of the soft-pack lithium battery is normal and the volume change is within the required value, but the surface is slightly damaged, the surface of the soft-pack lithium battery is repairable. Therefore, it is sorted to the repair station, and the damage on its surface can be repaired and it can continue to be used.

[0135] Through the above-mentioned sorting, defective soft-pack lithium batteries can be repaired and reused as much as possible, which improves the yield rate and helps save costs.

[0136] It should be noted that the pre-chemical device 2 and the formation device 3 described in the present invention can both perform pre-chemical and formation on multiple soft-pack lithium batteries at one time. The accompanying drawings only show the structure of one soft-pack lithium battery for ease of understanding. In fact, one pre-chemical device 2 and the formation device 3 can respectively include multiple Figure 2 , Figure 3 The structure shown.

[0137] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention is disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments according to the technology of the present invention are within the scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.

Claims

1. A formation process for a soft-pack lithium battery, characterized in that: The following steps are involved: A. pre-treatment of the soft-pack lithium battery to form a dense sei film, and exhaust treatment of the soft-pack lithium battery during and / or after the pre-treatment process; B. Perform n formation treatments on the soft-pack lithium battery at a formation temperature of T n , the formation current is I n ; Where n is a natural number and 2≤n≤6, the formation temperature T n The unit is ℃, the formation current I n The unit is mA, the formation temperature is T n , the formation current In increases with the increase of n; C. Perform aging treatment on soft-pack lithium batteries and monitor the voltage and appearance changes of soft-pack lithium batteries; D. Sort and process soft-pack lithium batteries.

2. The formation process of the soft-pack lithium battery according to claim 1, characterized in that: Step A specifically includes: A1. Perform a vacuum treatment on the soft-pack lithium battery; A2. Charge the soft-pack lithium battery and sense the pressure change inside the soft-pack lithium battery; if the pressure inside the soft-pack lithium battery exceeds the threshold, execute step A3, otherwise execute step A4; A3. Perform secondary degassing on the soft-pack lithium battery, and then proceed to step A4; A4. Sense the pressure change rate of the soft-pack lithium battery. If the pressure change rate is less than the preset value, vacuum the soft-pack lithium battery; A5. Keep charging the soft-pack lithium battery until the preset time is reached.

3. The formation process of the soft-pack lithium battery according to claim 2, characterized in that: A pre-chemical device for performing step A is provided, the pre-chemical device comprising a vacuum pump, a filter, a switch valve, an air pressure sensor, a charging module and a temperature control module, the vacuum pump is connected to the soft-pack lithium battery through the filter and the switch valve, the air pressure sensor is used to be inserted into the soft-pack lithium battery and sense the air pressure, the charging module is used to charge the soft-pack lithium battery, and the temperature control module is used to control the temperature of the soft-pack lithium battery; In step A2, it also includes sensing the rate of change of air pressure in the soft-pack lithium battery. If the rate of change of air pressure is greater than a preset value, the soft-pack lithium battery is cooled by a temperature control module; If the air pressure change rate of the soft-pack lithium battery does not exceed the lower threshold within a specific time, the temperature of the soft-pack lithium battery is increased through the temperature control module; In step A5, it specifically includes: Performing a cooling process on the soft-pack lithium battery so that the temperature of the soft-pack lithium battery is reduced to T'; The temperature of the soft-pack lithium battery is maintained at T', and then the soft-pack lithium battery is continuously charged until a preset time is reached.

4. The formation process of the soft-pack lithium battery according to claim 3, characterized in that: The pre-chemical device also includes a weighing module and a liquid replenishing module, the switch valve has a first input port, a second input port and an output port, the first input port is connected to the filter, the second input port is connected to the liquid replenishing module, and the output port is used to connect to the soft-pack lithium battery; Step A also includes: A6. Weigh the weight change of the soft-pack lithium battery using the weighing module; A7. Control the switch valve to switch to connect the second input port with the output port; A8. The refilling module refills the electrolyte of the soft-pack lithium battery until the weight of the soft-pack lithium battery returns to the weight before pre-treatment; A9.Discharge the soft-pack lithium battery.

5. The formation process of the soft-pack lithium battery according to claim 1, characterized in that: Step B specifically includes: B1. Heat the temperature of the soft-pack lithium battery to T n ; T n = k'*n, k' is a constant and the value range of k' is 15-20; B2. For soft pack lithium battery, the current value is I n Charge until the current charge of the soft-pack lithium battery becomes 100% of the total charge. Among them I n =n*I, I is the preset rated current value; B3. Repeat steps B1 and B2 for n times; Among them, k=1+2+…+n.

6. The formation process of the soft-pack lithium battery according to claim 5, characterized in that: When n>1, execute step B1, and keep I n-1 The current value is used to charge the soft-pack lithium battery, and the temperature of the soft-pack lithium battery is increased until the temperature of the soft-pack lithium battery increases from T n-1 Heating to T n Then, increase the current value to I n .

7. The formation process of the soft-pack lithium battery according to claim 5, characterized in that: A formation device for performing step B is provided, comprising an exhaust module, a temperature adjustment module, a power supply module and a sealing module, The exhaust module is used to communicate with the inside of the soft-pack lithium battery and exhaust the soft-pack lithium battery so that a negative pressure is formed inside the soft-pack lithium battery; The temperature control module is used to adjust the temperature of the soft-pack lithium battery; The power supply module is used to charge the soft-pack lithium battery; The sealing module is used to seal soft-pack lithium batteries.

8. The formation process of the soft-pack lithium battery according to claim 7, characterized in that: The sealing module is used to seal the soft-pack lithium battery, and specifically includes: Clamp the tube of the soft-pack lithium battery; Cutting the tube of the soft-pack lithium battery to reduce the length of the tube; Ultrasonic welding is performed on the tube of the soft-pack lithium battery to keep the tube closed; The tube of the soft-pack lithium battery is sealed with glue to seal and cover the tube.

9. The formation process of the soft-pack lithium battery according to claim 1, characterized in that: Step C specifically includes: C1. Place the soft-pack lithium battery for aging and monitor the voltage change of the soft-pack lithium battery; C2. Obtain the appearance changes of soft-pack lithium batteries during the aging process; C3. Based on the appearance changes and voltage changes of the soft-pack lithium battery, infer the aging state of the soft-pack lithium battery and record it.

10. The formation process of the soft-pack lithium battery according to claim 9, characterized in that: Step D specifically includes: D1. Obtain the voltage change of the soft-pack lithium battery. If the voltage change is within a preset range, the lithium battery is determined to be in the first state, otherwise it is determined to be in the second state; D2. Obtain an image of the soft-pack lithium battery, and obtain the volume change of the soft-pack lithium battery and whether there are signs of damage from the image of the soft-pack lithium battery; D3. Compare the volume change of the soft-pack lithium battery with the pre-stored data. If the volume change of the soft-pack lithium battery is within the preset range, the soft-pack lithium battery is determined to be in the third state, otherwise it is determined to be in the fourth state; D4. Determine the damage length and depth by pixel traces in the image. If there is no damage trace, the soft-pack lithium battery is determined to be in the fifth state; if the damage length and depth are both within the preset range, the soft-pack lithium battery is determined to be in the sixth state; if the damage length and / or depth exceeds the preset range, the soft-pack lithium battery is determined to be in the seventh state; D5. Sort the soft-pack lithium batteries as follows: When the soft-pack lithium battery is in any one of the second state, the fourth state, and the seventh state, the soft-pack lithium battery is sorted to a non-conforming station; Sorting the soft-pack lithium batteries in the first state, the third state, and the fifth state to the qualified stations; The soft-pack lithium batteries that are in the first state, the third state, and the sixth state are sorted to the repair station.

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