Lithium ion battery electrolyte repair method

Abstract

The invention discloses a lithium ion battery electrolyte repair method, and relates to the technical field of lithium ion batteries, the lithium ion battery electrolyte repair method comprises a to-be-supplemented battery cell arranged in the lithium ion battery, the battery cell comprises a side sealing area and a top sealing area which are subjected to heat sealing, and a first sealing area and a second sealing area which are not subjected to heat sealing, the method specifically comprises the following steps: S1, selecting lithium ion batteries with voltage and internal resistance within a process range and without damage and liquid leakage for later use; according to the lithium ion battery liquid supplementing repairing method, the infiltration effect of the electrolyte is guaranteed through a negative pressure-pressurization circulating liquid injection mode of negative pressure liquid injection and small-amount multiple liquid injection, and negative pressure liquid injection can effectively promote infiltration of the electrolyte by a lithium battery pole piece and a diaphragm, so that the electrolyte can be effectively prevented from being damaged. And multiple negative pressure pumping-pressurizing cycles are adopted, so that the wettability of the lithium ion battery can be promoted, and as negative pressure pumping-pressurizing cycle liquid injection is adopted, residual gas in the battery is pumped out through negative pressure pumping when the electrolyte is injected every time, and the air resistance is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion batteries, and in particular to a method for replenishing and repairing lithium ion batteries. Background Art

[0002] Referring to a Chinese patent, a method for refilling and repairing a soft-pack lithium-ion battery (Announcement No.: CN112259936A) includes: S1, a battery screening step, selecting soft-pack lithium-ion batteries with voltage and internal resistance within the process range, good appearance and no damage or leakage for standby; S2, a refilling step, piercing a layer of aluminum-plastic film in the area between the top seal and the laminate body to form a refilling hole, and slowly injecting electrolyte; S3, a degassing step, after the refilled soft-pack lithium-ion battery is left to stand for 15-30 minutes, the soft-pack lithium-ion battery is degassed; S4, a sealing step, sealing by glue sealing or heat sealing, the glue sealing method is to first use hot-melt EVA glue to quickly apply glue to the refilling hole, and then use silicone sealant to cover the EVA glue for secondary glue application and sealing, and the heat sealing method is to use a heat sealing head to heat-seal the refilling hole, which can effectively solve the problem of repairing and reusing retired gas-producing soft-pack lithium-ion batteries. However, in the prior art, the refilling and static methods of lithium batteries are to inject the lithium battery once and to let it stand once respectively. For power lithium batteries, due to the large injection volume and long standing time, the conventional single injection method is not conducive to the absorption of the electrolyte, resulting in poor injection stability and long static time, which affects the quality and consistency of lithium battery products. Therefore, the present invention proposes a lithium ion battery refilling and repair method to solve the above-mentioned problems. Summary of the invention 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a method for replenishing and repairing a lithium-ion battery, which solves the problem that the replenishing and standing methods of lithium batteries in the prior art are to respectively inject liquid and stand the lithium battery once, which is not conducive to the absorption of the electrolyte, resulting in poor injection stability and long standing time, thereby affecting the quality and consistency of lithium battery products.

[0003] (II) Technical solution To achieve the above objectives, the present invention is implemented through the following technical solutions: A lithium ion battery rehydration repair method, comprising a battery cell to be rehydrated arranged inside the lithium ion battery, the battery cell comprising a side sealing area and a top sealing area that have been heat-sealed, and a first sealing area and a second sealing area that have not been heat-sealed, and the specific rehydration repair steps are as follows: S1. Select the lithium-ion batteries with voltage and internal resistance within the process range and no damage or leakage for standby use; S2, weighing the lithium-ion battery for the first time; S2. Place the lithium-ion battery in a sealed box and evacuate the box; S3, circulating the lithium-ion battery for liquid replenishment and allowing it to stand; S4, after the filling is completed, heat-seal the sealing area of ​​the filling edge of the battery cell to be filled in the lithium-ion battery; S5. Open the sealed box and take out the lithium-ion battery.

[0004] Preferably, in step S3, the internal vacuum degree of the sealing box is -90 kPa, and the material of the sealing box is 304 stainless steel, and the national standard grade is 0Cr18Ni9.

[0005] Preferably, in step S5, after heat-sealing the sealing area of ​​the injection edge, nitrogen is introduced into the interior of the vacuum box to make the pressure inside and outside the sealed box the same.

[0006] Preferably, the liquid replenishing temperature in step S4 is controlled to be a constant temperature of 40°C.

[0007] Preferably, in step S4, the specific method for cyclically replenishing and standing the lithium-ion battery is: the lithium-ion battery is placed on the liquid filling station together with the clamp, and the liquid filling pump injects the electrolyte into the liquid filling cup of the liquid filling mechanism, and then the liquid filling substation enters the subsequent cyclic standing station along the guide rail, and the electrolyte is injected into the battery through multiple positive and negative pressure cycles until the injection of a predetermined amount of electrolyte is completed, that is, the "replenishing-standing" process of the lithium-ion battery is completed.

[0008] Preferably, in step S4, a liquid injection device is used to replenish the lithium-ion battery, and the liquid injection head on the liquid injection device is made of EP material, and a "()"-shaped sealing ring is embedded on the outside of its nozzle.

[0009] Preferably, when replenishing the liquid in step S4, after the lithium-ion battery is placed, the battery cell inside is placed vertically, with the opening edge of the sealing area of ​​the battery cell facing upward, and the liquid injection device injects the electrolyte into the battery cell from the opening of the sealing area.

[0010] Preferably, the lithium-ion battery rehydration and repair method further comprises: S6. Weigh the removed lithium-ion battery for the second time and compare it with the data obtained from the first weighing of the lithium-ion battery. If it is qualified, it will be moved out to the next process station.

[0011] (III) Beneficial effects The present invention provides a lithium-ion battery rehydration and repair method. Compared with the prior art, the method has the following beneficial effects: the method ensures the electrolyte infiltration effect through negative pressure injection and negative pressure-pressurization cycle injection of a small amount of multiple injections, wherein negative pressure injection can effectively promote the infiltration of the lithium battery pole piece and the diaphragm with the electrolyte, and multiple negative pressure-pressurization cycles are beneficial to promote the wettability of the lithium-ion battery, mainly because the negative pressure-pressurization cycle injection is adopted, so that each time the electrolyte is injected, the negative pressure is extracted to extract the residual gas inside the battery, reducing the air resistance, so that the electrolyte and the pole piece are in more complete contact; and the negative pressure-pressurization cycle can increase the pressure difference during injection, thereby improving the electrolyte infiltration efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of a battery cell structure provided by a lithium-ion battery rehydration and repair method of the present invention; Figure 2 A schematic diagram of a refilling and sealing process provided by a refilling and repairing method for a lithium-ion battery of the present invention; Figure 3 A lithium-ion battery rehydration and repair method according to the present invention provides a cyclic rehydration-stationary flow chart. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] See also Figure 1-Figure 3 , the embodiment of the present invention provides the following three technical solutions: Example 1 A method for refilling and repairing a lithium-ion battery comprises a battery cell to be refilled arranged inside the lithium-ion battery, wherein the battery cell comprises a side sealing area and a top sealing area that have been heat-sealed, and a first sealing area and a second sealing area that have not been heat-sealed. The specific steps of refilling and repairing are as follows: S1. Select the lithium-ion batteries with voltage and internal resistance within the process range and no damage or leakage for standby use; S2, weighing the lithium-ion battery for the first time; S3, placing the lithium-ion battery in a sealed box and evacuating the box; S4, circulating the lithium-ion battery for liquid replenishment and allowing it to stand; S5. After the filling is completed, the sealing area of ​​the filling edge of the battery cell to be filled in the lithium-ion battery is heat-sealed; after the filling is completed, the sealing area is pre-sealed to prevent air from entering the battery cell and contaminating the electrolyte; S6. Open the sealed box and take out the lithium-ion battery; S7, weigh the removed lithium-ion battery for the second time, and compare it with the data obtained from the first weighing of the lithium-ion battery. If it is qualified, move it to the next process station.

[0015] In the embodiment of the present invention, in step S3, the internal vacuum degree of the sealing box is -90 kPa, and the material of the sealing box is 304 stainless steel, and the national standard grade is 0Cr18Ni9, which effectively improves the sealing performance and corrosion resistance of the sealing box.

[0016] In the embodiment of the present invention, in step S5, after the sealing area of ​​the injection edge is heat-sealed, nitrogen is introduced into the interior of the vacuum box to make the pressure inside and outside the sealed box the same.

[0017] In the embodiment of the present invention, the liquid replenishing temperature in step S4 is controlled to be a constant temperature of 40° C., which accelerates the infiltration speed of the electrolyte into the battery cell.

[0018] In the embodiment of the present invention, in step S4, the specific method of circulating the liquid replenishment and standing the lithium-ion battery is as follows: the lithium-ion battery is placed on the liquid filling station (such as Figure 3 As shown in the figure, station 2), the injection pump injects the electrolyte into the injection cup of the injection mechanism, and then the injection substation enters the subsequent circulation station along the guide rail (such as Figure 3 As shown in Figure 3-10, the electrolyte is injected into the battery through multiple positive and negative pressure cycles until a predetermined amount of electrolyte is injected, that is, the "refilling-standing" process of the lithium-ion battery is completed.

[0019] Since the injection and standing are carried out in multiple times, the injection amount of each injection is small (the total injection amount is determined by the specifications of the power lithium battery), which is beneficial to the battery cell's absorption of the electrolyte; and since the injection amount is small, the electrolyte is easy to penetrate after each injection, and the overall time of the injection and standing process is greatly reduced compared to the conventional method of one injection and standing.

[0020] Through negative pressure injection and negative pressure-pressurization cycle injection of small amount of multiple injections, the infiltration effect of electrolyte is guaranteed to promote the infiltration of electrolyte. Negative pressure injection can effectively promote the infiltration of lithium battery pole piece and diaphragm into electrolyte, and the use of multiple negative pressure-pressurization cycles is conducive to promoting the wettability of lithium-ion batteries. This is mainly because the use of negative pressure-pressurization cycle injection makes it possible to extract the residual gas inside the battery each time the electrolyte is injected, reduce air resistance, and make the electrolyte contact with the pole piece more fully; and the negative pressure-pressurization cycle can increase the pressure difference during injection. According to Darcy's law, the electrolyte infiltration efficiency is proportional to the pressure difference. Increasing the pressure difference can improve the electrolyte infiltration efficiency. While the negative pressure is pumped inside the battery cell, the electrolyte is injected into the battery cell under the action of the pressure difference because the air pressure inside the battery cell is lower than the atmospheric pressure. When the battery cell is pressurized, the electrolyte is no longer injected, that is, while the negative pressure is pumped and pressurized, a small amount of multiple injections are achieved to improve the infiltration efficiency and injection efficiency. And a small amount of electrolyte is injected each time to expand the contact area between the electrolyte and the pole piece and the diaphragm, and to improve the electrolyte infiltration efficiency.

[0021] Example 2 A method for refilling and repairing a lithium-ion battery comprises a battery cell to be refilled arranged inside the lithium-ion battery, wherein the battery cell comprises a side sealing area and a top sealing area that have been heat-sealed, and a first sealing area and a second sealing area that have not been heat-sealed. The specific steps of refilling and repairing are as follows: S1. Select the lithium-ion batteries whose voltage and internal resistance are within the process range and have no damage or leakage for standby use; S2, weighing the lithium-ion battery for the first time; S3, placing the lithium-ion battery in a sealed box and evacuating the box; S4, circulating the lithium-ion battery for liquid replenishment and allowing it to stand; S5. After the filling is completed, the sealing area of ​​the filling edge of the battery cell to be filled in the lithium-ion battery is heat-sealed; after the filling is completed, the sealing area is pre-sealed to prevent air from entering the battery cell and contaminating the electrolyte; S6. Open the sealed box and take out the lithium-ion battery; S7, weigh the removed lithium-ion battery for the second time, and compare it with the data obtained from the first weighing of the lithium-ion battery. If it is qualified, move it to the next process station.

[0022] In the embodiment of the present invention, in step S3, the internal vacuum degree of the sealing box is -90 kPa, and the material of the sealing box is 304 stainless steel, and the national standard grade is 0Cr18Ni9, which effectively improves the sealing performance and corrosion resistance of the sealing box.

[0023] In the embodiment of the present invention, in step S5, after the sealing area of ​​the injection edge is heat-sealed, nitrogen is introduced into the interior of the vacuum box to make the pressure inside and outside the sealed box the same.

[0024] In the embodiment of the present invention, the liquid replenishing temperature in step S4 is controlled to be a constant temperature of 40°C, which accelerates the infiltration speed of the electrolyte into the battery cell. In addition, a small amount of electrolyte is injected each time to achieve the purpose of expanding the contact area between the electrolyte and the electrode and the diaphragm, and improving the electrolyte infiltration efficiency.

[0025] In the embodiment of the present invention, in step S3, the specific method of circulating the liquid replenishment and standing the lithium-ion battery is as follows: the lithium-ion battery is placed on the liquid filling station (such as Figure 3 As shown in the figure, station 2), the injection pump injects the electrolyte into the injection cup of the injection mechanism, and then the injection substation enters the subsequent circulation station along the guide rail (such as Figure 3 As shown in Figure 3-10, the electrolyte is injected into the battery through multiple positive and negative pressure cycles until a predetermined amount of electrolyte is injected, that is, the "refilling-standing" process of the lithium-ion battery is completed.

[0026] Since the injection and standing are carried out in multiple times, the injection amount of each injection is small (the total injection amount is determined by the specifications of the power lithium battery), which is beneficial to the battery cell's absorption of the electrolyte; and since the injection amount is small, the electrolyte is easy to penetrate after each injection, and the overall time of the injection and standing process is greatly reduced compared to the conventional method of one injection and standing.

[0027] Through negative pressure injection and negative pressure-pressurization cycle injection of small amount of multiple injections, the infiltration effect of electrolyte is guaranteed to promote the infiltration of electrolyte. Negative pressure injection can effectively promote the infiltration of lithium battery pole piece and diaphragm into electrolyte, and the use of multiple negative pressure-pressurization cycles is conducive to promoting the wettability of lithium-ion batteries. This is mainly because the use of negative pressure-pressurization cycle injection makes it possible to extract the residual gas inside the battery each time the electrolyte is injected, reduce air resistance, and make the electrolyte contact with the pole piece more fully; and the negative pressure-pressurization cycle can increase the pressure difference during injection. According to Darcy's law, the electrolyte infiltration efficiency is proportional to the pressure difference. Increasing the pressure difference can improve the electrolyte infiltration efficiency. While negative pressure is pumped into the battery cell, the electrolyte is injected into the battery cell under the action of the pressure difference because the air pressure inside the battery cell is lower than atmospheric pressure. When the battery cell is pressurized, the electrolyte is no longer injected. That is, while the negative pressure is pumped and pressurized cycle is performed, small amounts of liquid are injected multiple times to improve the infiltration efficiency and the liquid injection efficiency.

[0028] In the embodiment of the present invention, in step S3, a liquid injection device is used to replenish the lithium-ion battery, and the liquid injection head on the liquid injection device is made of EP material, and a "()"-shaped sealing ring is inlaid on the outside of its nozzle. Among them, the EP material is low in cost, high in utilization rate, and wear-resistant, so that the battery and the liquid injection machine are separated, and it does not react with the electrolyte, effectively reducing the leakage of the electrolyte. When the atmospheric pressure is restored, the electrolyte remaining in the liquid injection head tooling enters the battery with almost no electrolyte leakage, ensuring the accuracy of liquid replenishment.

[0029] In the embodiment of the present invention, when replenishing the liquid in step S3, after the lithium-ion battery is placed, the battery cell inside is placed vertically, so that the opening edge of the sealing area of ​​the battery cell faces upward, and the liquid injection device injects the electrolyte into the battery cell from the opening of the sealing area. The residual gas in the battery cell, the gas brought in by the electrolyte during the liquid injection, and the gas discharged by the electrolyte during the infiltration of the electrode and the diaphragm will move up to the air bag area between the winding core and the sealing area due to the low density. In the subsequent processing, the second sealing is performed and the air bag area is cut off to avoid bloating affecting the battery quality.

[0030] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0031] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0032] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for refilling and repairing a lithium-ion battery, comprising a battery cell to be refilled arranged inside the lithium-ion battery, characterized in that: The battery cell includes a side sealing area and a top sealing area that have been heat-sealed, and a first sealing area and a second sealing area that have not been heat-sealed. The specific steps of liquid replenishment and repair are as follows: S1. Select the lithium-ion batteries with voltage and internal resistance within the process range and without damage or leakage for standby use; S2, weighing the lithium-ion battery for the first time; S3, placing the lithium-ion battery in a sealed box and evacuating the box; S4, circulating the lithium-ion battery for liquid replenishment and allowing it to stand; S5. After the liquid filling is completed, heat-seal the sealing area of ​​the liquid filling edge of the battery cell to be filled in the lithium-ion battery; S6. Open the sealed box and take out the lithium-ion battery.

2. A lithium-ion battery rehydration and repair method according to claim 1, characterized in that: In step S3, the internal vacuum degree of the sealing box is -90 kPa, and the material of the sealing box is 304 stainless steel, and the national standard grade is 0Cr18Ni9.

3. A lithium-ion battery rehydration and repair method according to claim 1, characterized in that: In the step S5, after the sealing area of ​​the liquid injection edge is heat-sealed, nitrogen is introduced into the interior of the vacuum box to make the pressure inside and outside the sealed box the same.

4. A lithium-ion battery rehydration and repair method according to claim 1, characterized in that: In step S4, the temperature of the liquid replenishment is controlled to be a constant temperature of 40°C.

5. A lithium-ion battery rehydration and repair method according to claim 1, characterized in that: In step S4, the specific method for cyclically replenishing and standing the lithium-ion battery is as follows: the lithium-ion battery is placed on the liquid filling station together with the fixture, and the liquid filling pump injects the electrolyte into the liquid filling cup of the liquid filling mechanism. Then, the liquid filling substation enters the subsequent cyclic standing station along the guide rail, and the electrolyte is injected into the battery through multiple positive and negative pressure cycles until the injection of a predetermined amount of electrolyte is completed, that is, the "liquid filling-standing" process of the lithium-ion battery is completed.

6. A lithium-ion battery rehydration and repair method according to claim 1, characterized in that: In the step S4, a liquid injection device is used to replenish the lithium-ion battery, and the liquid injection head on the liquid injection device is made of EP material, and a "()"-shaped sealing ring is embedded on the outside of its nozzle.

7. A lithium-ion battery rehydration and repair method according to claim 6, characterized in that: During the liquid replenishment in step S4, after the lithium-ion battery is placed, the battery cell inside is placed vertically, with the opening edge of the sealing area of ​​the battery cell facing upward, and the liquid injection device injects the electrolyte into the battery cell from the opening of the sealing area.

8. A lithium-ion battery rehydration and repair method according to claim 1, characterized in that: The lithium-ion battery rehydration repair method also includes: S7, weigh the removed lithium-ion battery for the second time, and compare it with the data obtained from the first weighing of the lithium-ion battery. If it is qualified, move it to the next process station.

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