A method for collecting electrolyte after formation of soft-pack lithium-ion battery

Abstract

The present invention discloses a method for collecting electrolyte after formation of a soft-pack lithium-ion battery, and the method comprises the following steps: S1, placing the formed battery cell on a secondary sealing platform for preliminary separation of the electrolyte, wherein the formed battery cell comprises a battery cell body and an air bag; S2, heat-sealing a funnel-shaped seal on the air bag, wherein the funnel-shaped seal separates the air bag into a first part and a second part; S3, hot-pressing the heat-sealed battery cell on a secondary sealing device; S4, after the electrolyte is separated into the first part, using a secondary sealing head to encapsulate the formed battery cell to obtain the electrolyte. The method solves the problem that the electrolyte in the existing soft-pack battery cell manufacturing process is not recycled or leaks into the air and cannot be reused. The method of the present invention can reduce the waste of electrolyte after formation and secondary sealing, and the effect is remarkable; and the electrolyte can be reused after recycling.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion batteries, in particular to a method for collecting electrolyte after formation of a soft-pack lithium ion battery. Background Art

[0002] Lithium-ion batteries are currently widely used in the field of new energy vehicles. They are characterized by high safety, high energy density, and green and pollution-free. Soft-pack lithium-ion batteries are a common lithium-ion battery structure on the market. They are encapsulated with aluminum-plastic film, filled with pole cores, and use electrolyte as the transmission medium between the positive and negative electrodes. The electrolyte is the core electrochemical unit, and the amount of electrolyte and film-forming additives directly determine the life of the battery. For the amount of electrolyte and the residual amount after formation, in order to achieve the purpose of reducing costs and increasing efficiency, the amount of electrolyte needs to be controlled and recycled.

[0003] After formation, soft-pack lithium-ion batteries need to be vented and sealed again. The current conventional process is to directly cut the airbag bag, vacuum it to extract the gas and electrolyte at the same time, and expose the electrolyte to the air, causing failure and making it impossible to fully recycle.

[0004] "A method for recovering electrolyte of lithium-ion batteries" disclosed in Chinese patent documents, with publication number CN106252777A, relates to a method for recovering electrolyte of lithium-ion batteries, comprising cleaning and discharging waste lithium-ion batteries, and piercing a puncture hole with a depth less than the thickness of the shell on the battery shell; under vacuum conditions, sending the battery into an electrolyte collection device that maintains dew point conditions; using a needle to pierce the puncture hole on the battery to form a leakage hole, and quickly transferring it to the top of the electrolyte collection tank, and the electrolyte in the battery flows out of the leakage hole and directly enters the electrolyte collection tank; after the electrolyte flows out naturally for 30 to 60 minutes, using a pneumatic pressure device to intermittently squeeze the battery from the top of the battery to make the electrolyte in the battery flow out completely; adding the electrolyte in the electrolyte collection tank to a nitrogen-protected reactor, and then adding a barium oxide ethanol solution with a concentration of 30% to 50%, recovering lithium fluoride for recycling. However, in the Chinese patent with publication number CN106252777A, the collection method is to collect at the finished product stage, not at the battery cell formation stage, and the electrolyte waste in the formation stage is still relatively large. Summary of the invention

[0005] The invention solves the problem that the electrolyte in the existing soft-pack battery cell manufacturing process is not recovered or leaks into the air and cannot be reused, and proposes a method for collecting the electrolyte after formation of a soft-pack lithium-ion battery, which reduces the waste of electrolyte after formation and secondary sealing, and has a significant effect; and the electrolyte can be reused after recovery.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme: a method for collecting electrolyte after formation of a soft-pack lithium-ion battery, comprising the following steps:

[0007] S1, placing the formed battery cell on a second sealing platform for preliminary separation of the electrolyte, wherein the formed battery cell includes a battery cell body and an airbag bag;

[0008] S2, a funnel-shaped seal is heat-sealed on the airbag bag, and the funnel-shaped seal separates the airbag bag into a first part and a second part;

[0009] S3, the heat-sealed battery cell is hot pressed on the secondary sealing equipment;

[0010] S4, after the electrolyte is separated into the first part, the formed battery cell is packaged using a second sealing head to obtain the electrolyte.

[0011] In the present invention, after the formed battery cell is placed on a secondary sealing platform for preliminary separation, a funnel-shaped seal is pre-sealed on the airbag bag, and then a pressure plate is applied to the battery cell body to squeeze the electrolyte and the gas into the airbag bag to separate the electrolyte and the gas. The funnel-shaped seal can prevent a large amount of electrolyte from flowing back. Finally, a secondary seal is performed to seal the gas and the electrolyte to obtain the final recovered electrolyte. The present invention can achieve sealed recovery of the electrolyte.

[0012] Preferably, the step S1 is specifically as follows: the formed battery cell is placed on a second sealing platform, and the second sealing platform is tilted downward by 0° to 60°, so that the free electrolyte in the battery cell body flows obliquely to the airbag bag. In the present invention, the second sealing platform is tilted, and the tilt angle is determined according to actual conditions, so that the electrolyte flows out naturally obliquely downward; the initial separation of the electrolyte can be completed.

[0013] Preferably, step S2 comprises the following steps:

[0014] S21, after preliminary separation, heat-seal the airbag bag with two heat-seal heads that are not connected to each other, the heat-seal shape is funnel-shaped, the narrow end of the funnel-shaped seal is away from the battery body; the distance between the wide end of the funnel-shaped seal and the leftmost side of the battery body is d;

[0015] S22, after heat sealing, the airbag bag is separated into a first part and a second part, and the area of ​​the second part accounts for 50% or more of the total area of ​​the airbag bag. In the present invention, the heat sealing temperature is 145-195°C, and the heat sealing pressure is 0.2-0.6MPa; the funnel-shaped seal divides the airbag bag into two parts, one side of the funnel stores electrolyte, and the other side stores gas. The funnel-shaped seal can prevent a large amount of electrolyte from flowing back to the gas side. After edge sealing (second sealing), the electrolyte does not contact the air, and sealed recovery is achieved.

[0016] Preferably, the step S3 is specifically: hot pressing the battery cell, the pressure range is 29.4-196N, the vacuum degree is ≤-90KPa, and the vacuum is maintained for 4-10s. In the present invention, the step S3 is mainly to squeeze the residual electrolyte and gas in the battery cell body into the airbag bag.

[0017] Preferably, step S4 comprises the following steps:

[0018] S41, after the electrolyte and gas are concentrated in the airbag bag, under the action of gravity and the funnel-shaped seal, after the electrolyte is separated into the first part, the funnel-shaped seal narrow mouth is completely sealed with a heat-sealing head, and the length of the sealing head is greater than the opening distance L of the funnel-shaped seal narrow mouth;

[0019] S42, after sealing, the bayonet in the second sealing device pierces the second part of the airbag bag, and the second sealing device is vacuumed at the same time, and the battery cell is packaged using the second sealing head to form a second seal, and the second seal position is in the gap between the wide end of the funnel-shaped seal and the leftmost side of the battery body, and the airbag bag is cut along the second seal to obtain the sealed and collected electrolyte. In the present invention, after the electrolyte and gas of the battery body are discharged, the narrow end of the funnel-shaped seal is heat-sealed and the wide end of the funnel-shaped seal is heat-pressed and sealed (second seal) to completely isolate the first part of the airbag bag from the second part.

[0020] Preferably, the opening distance L of the funnel-shaped seal narrow opening is 10% to 60% of the total height of the battery cell. In the present invention, the opening distance L of the funnel-shaped seal narrow opening is preferably 10 to 80 mm.

[0021] Preferably, the angle between the funnel-shaped seal and the edge of the airbag bag is 30°≤a≤60°. In the present invention, the angle between the funnel-shaped seal and the edge of the airbag bag is preferably 45°.

[0022] The beneficial effects of the present invention are as follows: the method for collecting electrolyte after formation of a soft-pack lithium-ion battery of the present invention reduces the waste of electrolyte after formation and secondary sealing, and the effect is remarkable; and the electrolyte can be reused after being recovered. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a battery cell in a method for collecting electrolyte after formation of a soft-pack lithium-ion battery of the present invention;

[0024] Among them, 1. battery body 2. funnel-shaped seal 3. second seal 4. first part 5. second part d. distance L between the wide end of the funnel-shaped seal and the leftmost side of the battery body, opening distance a of the narrow mouth of the funnel-shaped seal, and angle between the funnel-shaped seal and the edge of the airbag bag. DETAILED DESCRIPTION

[0025] Example:

[0026] This embodiment provides a method for collecting electrolyte after formation of a soft-pack lithium-ion battery. Figure 1 , mainly includes the following steps.

[0027] Step S1, placing the formed battery cell on the second sealing platform to achieve preliminary separation of the electrolyte; specifically, in this step, the battery cell used includes a battery cell body 1 and an airbag bag.

[0028] In the specific step S1, after the formed battery cell is placed on the second sealing platform, the second sealing platform is tilted downward, and the specific tilt angle is 0° to 60° to ensure that the free electrolyte inside the battery cell body 1 flows into the airbag bag. In the present invention, the second sealing platform is tilted to allow the electrolyte to flow out naturally downward, which can complete the initial separation of the electrolyte.

[0029] Step S2 , heat-sealing a funnel-shaped seal 2 on the airbag bag, wherein the funnel-shaped seal 2 separates the airbag bag into a first part 4 and a second part 5 .

[0030] Specifically, step S2 includes step S21 and step S22.

[0031] Step S21, after the initial separation, heat-seal the airbag bag using two heat-seal heads that are not connected to each other, the heat-seal shape is funnel-shaped, and the narrow end of the funnel-shaped seal is away from the battery body; wherein the distance between the wide end of the funnel-shaped seal and the leftmost side of the battery body is d. Specifically, in this embodiment, d is preferably 5 to 25 cm.

[0032] Step S22, after heat sealing, the airbag bag is divided into a first part 4 and a second part 5, and the area of ​​the second part 4 accounts for 50% or more of the total area of ​​the airbag bag. In this embodiment, the area of ​​the second part 4 is preferably 50% to 85% of the total area of ​​the airbag bag.

[0033] In the present invention, the heat sealing temperature is 145-195° C., and the heat sealing pressure is 0.2-0.6 MPa. The funnel-shaped seal divides the airbag bag into two parts, one side of the funnel stores electrolyte, and the other side stores gas. The funnel-shaped seal can prevent a large amount of electrolyte from flowing back to the gas side. After edge sealing (second seal), the electrolyte does not contact the air, thereby achieving sealed recovery.

[0034] Step S3, hot pressing the heat-sealed battery cell on a secondary sealing device; specifically, the hot pressing pressure is 29.4-196N, the vacuum degree is less than or equal to -90KPa, and the vacuum needs to be maintained for 4-10s to squeeze the residual electrolyte and gas in the battery cell body 1 into the airbag bag.

[0035] Step S4, after the electrolyte is separated into the first part 4, the formed battery cell is packaged using a double sealing head to obtain the electrolyte.

[0036] Specifically, step S4 includes step S41 and step S42.

[0037] Step S41, after the electrolyte and gas are concentrated in the airbag bag, under the action of gravity and the funnel-shaped seal 2, after the electrolyte is separated to the first part 4, the funnel-shaped seal narrow mouth is completely sealed with a heat-sealing head, and the length of the sealing head is greater than the opening distance L of the funnel-shaped seal narrow mouth; in this process, the funnel-shaped seal narrow mouth is heat-sealed, and in this embodiment, the length of the sealing head is 10 to 20 mm longer than the opening distance L of the funnel-shaped seal narrow mouth.

[0038] Step S42, the bayonet in the secondary sealing device then pierces the second part 5 of the airbag bag, and at the same time the secondary sealing device is vacuumed, and the battery cell is encapsulated with the secondary sealing head to form a secondary seal 3, the location of the secondary seal 3 is specifically in the gap between the wide end of the funnel-shaped seal and the leftmost side of the battery body 1, and finally the airbag bag is cut off along the secondary seal 3 to obtain the sealed and collected electrolyte. In this process, the wide end of the funnel-shaped seal is hot-pressed and sealed.

[0039] In the present invention, after the electrolyte and gas in the battery body are discharged, the narrow end of the funnel-shaped seal is heat-sealed and the wide end of the funnel-shaped seal is heat-pressed and sealed (two seals) to completely separate the first part and the second part of the airbag bag.

[0040] In the present invention, the opening distance L of the funnel-shaped seal narrow opening is 10% to 60% of the total height of the battery cell. In this embodiment, the opening distance L of the funnel-shaped seal narrow opening is preferably 10 to 80 mm.

[0041] In the present invention, the angle a between the funnel-shaped seal and the edge of the airbag bag satisfies 30°≤a≤60°. In this embodiment, the angle a between the funnel-shaped seal and the edge of the airbag bag is preferably 45°.

[0042] In the present invention, after the formed battery cell is placed on a secondary sealing platform for preliminary separation, a funnel-shaped seal is pre-sealed on the airbag bag, and then a pressure plate is applied to the battery cell body to squeeze the electrolyte and the gas into the airbag bag to separate the electrolyte and the gas. The funnel-shaped seal can prevent a large amount of electrolyte from flowing back. Finally, a secondary seal is performed to seal the gas and the electrolyte to obtain the final recovered electrolyte. The present invention can achieve sealed recovery of the electrolyte.

[0043] The above embodiments are further elaborations and illustrations of the present invention for ease of understanding, and are not limitations of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for collecting electrolyte after formation of a soft-pack lithium-ion battery, characterized in that: The following steps are involved: S1, placing the formed battery cell on a second sealing platform for preliminary separation of the electrolyte, wherein the formed battery cell includes a battery cell body and an airbag bag; S2, a funnel-shaped seal is heat-sealed on the airbag bag, and the funnel-shaped seal separates the airbag bag into a first part and a second part; the heat-sealed shape is funnel-shaped, and the narrow end of the funnel-shaped seal is away from the battery body; the distance between the wide end of the funnel-shaped seal and the leftmost side of the battery body is d; S3, the heat-sealed battery cell is hot pressed on the secondary sealing equipment; S4, after the electrolyte is separated into the first part, the formed battery cell is packaged using a second sealing head to obtain the electrolyte.

2. The method for collecting electrolyte after formation of a soft-pack lithium-ion battery according to claim 1, characterized in that: The step S1 specifically includes: placing the formed battery cell on a second sealing platform, which is tilted downward by 0° to 60°, so that the free electrolyte in the battery cell body flows obliquely to the airbag bag.

3. A method for collecting electrolyte after formation of a soft-pack lithium-ion battery according to claim 1 or 2, characterized in that: The step S2 comprises the following steps: S21, after the initial separation, heat-sealing the airbag bag using two heat-sealing heads that are not connected to each other; S22, after heat sealing, the airbag bag is separated into a first part and a second part, and the area of ​​the second part accounts for 50% or more of the total area of ​​the airbag bag.

4. The method for collecting electrolyte after formation of a soft-pack lithium-ion battery according to claim 3, characterized in that: The step S3 specifically includes: hot pressing the battery cell, with a pressure range of 29.4 to 196N, a vacuum degree ≤-90KPa, and maintaining the vacuum for 4 to 10 seconds.

5. The method for collecting electrolyte after formation of a soft-pack lithium-ion battery according to claim 4, characterized in that: The step S4 comprises the following steps: S41, after the electrolyte and gas are concentrated in the airbag bag, under the action of gravity and the funnel-shaped seal, after the electrolyte is separated into the first part, the funnel-shaped seal narrow mouth is completely sealed with a heat-sealing head, and the length of the sealing head is greater than the opening distance L of the funnel-shaped seal narrow mouth; S42, after sealing, the bayonet in the second sealing device pierces the second part of the airbag bag, and the second sealing device is vacuumed at the same time, and the battery cell is packaged using the second sealing head to form a second seal. The second seal position is in the gap between the wide end of the funnel-shaped seal and the leftmost side of the battery cell body. The airbag bag is cut along the second seal to obtain the sealed and collected electrolyte.

6. The method for collecting electrolyte after formation of a soft-pack lithium-ion battery according to claim 5, characterized in that: The opening distance L of the funnel-shaped seal narrow opening is 10% to 60% of the total height of the battery core.

7. The method for collecting electrolyte after formation of a soft-pack lithium-ion battery according to claim 5, characterized in that: The included angle a between the funnel-shaped seal and the edge of the airbag bag satisfies 30°≤a≤60°.

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