Lithium ion battery liquid injection method

Abstract

The invention relates to a lithium ion battery liquid injection method which comprises the following steps: S1, connecting a retainer cup injected with electrolyte with a liquid injection port of a lithium ion battery, and putting the retainer cup and the lithium ion battery into the same sealed space; s2, the sealed space is vacuumized, and pressure maintaining is conducted under the target vacuum degree; s3, the sealed space is charged with positive pressure in a stepped mode, and pressure maintaining is conducted under the target positive pressure; s4, sequentially repeating the steps S2 and S3 for a plurality of times; and S5, breaking pressure to complete liquid injection. According to the invention, through the principle of multiple vacuum-stepped positive pressure circulation, the retainer cup injected with electrolyte and the lithium ion battery are simultaneously placed in the sealed space, the retainer cup is communicated with the liquid injection port of the lithium ion battery, when the sealed space is vacuumized, the retainer cup and the lithium ion battery can be synchronously vacuumized, and then the sealed space is charged with positive pressure in a stepped manner; and the electrolyte in the retainer cup is slowly injected into the lithium ion battery, so that the effect of infiltrating and absorbing the electrolyte by the battery cell pole piece is improved, the electrolyte is infiltrated thoroughly, and the electrolyte injection efficiency is improved.

Description

Technical Field

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

[0002] With the rapid development of lithium-ion batteries in the energy storage field and the electric vehicle industry, the industry has put forward higher requirements for the performance of lithium-ion batteries such as energy density and capacity. The thickness of the winding core has been increased to a certain extent, resulting in a reduction in the remaining space in the battery shell. At present, the main injection processes for lithium-ion batteries are normal pressure injection and isobaric injection.

[0003] Normal pressure filling means that the outer surface of the battery is under atmospheric pressure, and the liquid surface in the filling cup is protected by air pressure. The electrolyte enters the battery through the pressure difference. When the internal pressure of the battery is lower than the pressure on the liquid surface in the filling cup, the liquid enters the battery. The greater the pressure difference between the two, the greater the liquid flow rate. To increase the filling efficiency, 0 to 0.2 MPa is usually added to the liquid surface in the filling cup. However, due to the excessive pressure difference between the inside and outside of the battery, the battery surface is prone to expansion and deformation, which leads to reduced product quality.

[0004] Isobaric injection is to place the battery to be injected and the injection cup containing a preset amount of electrolyte in a sealed injection chamber of the isobaric injection equipment in close contact, and then circulate high pressure, release pressure, or add low pressure (vacuum) inside the sealed chamber to achieve injection and exhaust cycles under the condition of equal pressure inside and outside the battery, until the preset amount of electrolyte is completely injected into the battery. However, isobaric injection uses one-step high pressure and the high pressure is only 650KPa. The injection level line is high and is only located below the injection hole. The effect of the electrolyte being pressed down to immerse into the battery is not obvious, the electrolyte is not thoroughly infiltrated, and abnormal liquid bubbling is prone to occur. The electrolyte penetrates into the explosion-proof valve, causing the blue film on the surface of the explosion-proof valve to fall off, and the electrolyte pollution affects the appearance of the finished battery. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a lithium-ion battery injection method, which uses a stepped high-pressure-isobaric injection process to inject electrolyte into the interior of the battery cell based on the principle of multiple vacuum-positive pressure static cycles, and can ensure that the battery explosion-proof film is not damaged under high pressure and the battery appearance is not deformed, while the rate of electrode infiltration and absorption of electrolyte is prolonged as much as possible, thereby improving the injection efficiency of the production process.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a lithium ion battery injection method, which comprises the following steps: S1. Connect the cup filled with electrolyte to the injection port of the lithium-ion battery, and place the cup and the lithium-ion battery in the same sealed space; S2. Evacuate the sealed space and maintain pressure at the target vacuum degree; S3. The sealed space is charged with positive pressure in a stepped manner and maintained at the target positive pressure; S4. Repeat steps S2 and S3 several times; S5. Break the pressure and complete the injection.

[0007] The present invention adopts the principle of multiple vacuum-step positive pressure cycles, places the sleeve cup filled with electrolyte and the lithium ion battery in a sealed space at the same time, the sleeve cup is connected with the injection port of the lithium ion battery, and when the sealed space is evacuated, the sleeve cup and the lithium ion battery can be evacuated synchronously, and then the sealed space is charged with positive pressure in a stepwise manner, so that the electrolyte in the sleeve cup is slowly injected into the lithium ion battery, the effect of the battery core electrode sheet infiltrating and absorbing the electrolyte is improved, the electrolyte is thoroughly infiltrated, the phenomenon of bubbling is avoided, the explosion-proof film of the battery is avoided to be damaged, the appearance of the battery is avoided to be affected, and the injection efficiency is improved.

[0008] As a further improvement of the above solution of the present invention, in step S2, the target vacuum degree is -90±10 KPa, and the pressure holding time at the target vacuum degree is 60-65 s.

[0009] As a further improvement of the above solution of the present invention, in step S2, the vacuuming time is ≤40s.

[0010] As a further improvement of the above scheme of the present invention, in step S3, the stepped positive pressure charging includes: charging the sealed space with positive pressure to a first pressure and maintaining the pressure; then charging the sealed space with positive pressure to a second positive pressure and maintaining the pressure, the second positive pressure is greater than the first positive pressure; then charging the sealed space with positive pressure to a third positive pressure and maintaining the pressure, the third positive pressure is greater than the second positive pressure; then charging the sealed space with positive pressure to a target positive pressure and maintaining the pressure, the target positive pressure is greater than the third positive pressure.

[0011] As a further improvement of the above scheme of the present invention, the first pressure is 0 KPa, and the pressure-holding time at the first pressure is 60-65 s; and / or, the second positive pressure is 180 KPa, and the pressure-holding time at the second pressure is 30-35 s; and / or, the third pressure is 400 KPa, and the pressure-holding time at the third pressure is 30-35 s; and / or, the target positive pressure is ≥650 kPa, and the pressure-holding time at the target pressure is ≥250 s.

[0012] As a further improvement of the above solution of the present invention, in step S4, steps S2 and S3 are repeated three times in sequence.

[0013] As a further improvement of the above scheme of the present invention, in step S3, the stepwise positive pressure charging includes: charging the sealed space with positive pressure to a first pressure and maintaining the pressure; and then charging the sealed space with positive pressure to a target positive pressure and maintaining the pressure.

[0014] As a further improvement of the above scheme of the present invention, the first pressure is 0 KPa, and the pressure-maintaining time at the first pressure is 180-185 s; and / or the target positive pressure is ≥680 kPa, and the pressure-maintaining time at the target positive pressure is ≥240 s.

[0015] As a further improvement of the above solution of the present invention, in step S4, steps S2 and S3 are repeated twice in sequence.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts the principle of multiple vacuum-step positive pressure cycles, places the sleeve cup filled with electrolyte and the lithium ion battery in a sealed space at the same time, the sleeve cup is connected with the injection port of the lithium ion battery, and when the sealed space is evacuated, the sleeve cup and the lithium ion battery can be evacuated synchronously, and then the sealed space is charged with positive pressure in a stepwise manner, so that the electrolyte in the sleeve cup is slowly injected into the lithium ion battery, the effect of the battery core electrode sheet infiltrating and absorbing the electrolyte is improved, the electrolyte is thoroughly infiltrated, the phenomenon of bubbling is avoided, the explosion-proof film of the battery is avoided to be damaged, the appearance of the battery is avoided to be affected, and the injection efficiency is improved.

[0017] The liquid injection method of the present invention can meet the high liquid injection weight requirements of large-capacity square aluminum shell lithium ion batteries and meet the requirements of one-time injection of electrolyte under high pressure conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A flow chart of a lithium-ion battery injection method proposed in an embodiment of the present invention; Figure 2 A schematic diagram of liquid injection of a lithium-ion battery proposed in an embodiment of the present invention.

[0019] Figure numerals: 1. static cover; 2. sleeve cup; 3. lithium-ion battery; 4. tray. DETAILED DESCRIPTION

[0020] For ease of understanding of the present invention, the present invention will be described more fully below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0022] Reference Figure 1 The present embodiment provides a lithium ion battery injection method, which comprises the following steps: S1. Connect the sleeve cup 2 filled with electrolyte to the injection port of the lithium-ion battery 3, and place the sleeve cup 2 and the lithium-ion battery 3 in the same sealed space.

[0023] This embodiment uses the sealed space provided by the static cover 1, and adopts the method of injecting a large amount of electrolyte from the injection station into a plurality of sleeve cups 2 for storage at one time, and the tray 4 containing the lithium-ion battery 3 and the sleeve cups 2 are placed into the static cover 1 together by a stacking trolley. Figure 2 As shown, the electrolyte with a large amount of liquid injection in the injection station is preferentially injected into multiple sets of cups 2 for storage at one time, and the tray 4 containing lithium-ion batteries 3 and the sets of cups 2 are placed in the static cover 1 together by a stacking trolley. Each battery tray 3 contains 32 lithium-ion batteries 3, and the battery tray 3 and the sets of cups 2 are placed in the sealed space of the static cover 1 of the pressurized static unit by a stacking trolley, and each static cover 1 contains 64 lithium-ion batteries 3.

[0024] S2. Evacuate the stationary cover 1 and maintain the pressure at the target vacuum degree.

[0025] When the static cover 1 is evacuated, since the sleeve cup 2 is connected to the lithium-ion battery 3, the sleeve cup 2 and the lithium-ion battery 3 are evacuated simultaneously. In this embodiment, the evacuation time is ≤40s, the target vacuum degree is -90±10KPa, and the vacuum holding time is 60-65s.

[0026] S3. Perform stepwise positive pressure charging on the stationary cover 1 and maintain the pressure at the target positive pressure.

[0027] The static cover 1 is charged with positive pressure to a first pressure and maintained; then the static cover 1 is charged with positive pressure to a second positive pressure and maintained, the second positive pressure is greater than the first positive pressure; then the static cover 1 is charged with positive pressure to a third positive pressure and maintained, the third positive pressure is greater than the second positive pressure; then the static cover 1 is charged with positive pressure to a target positive pressure and maintained, the target positive pressure is greater than the third positive pressure. The static cover 1 is charged with positive pressure in a step-by-step manner, so that the electrolyte in the sleeve cup 2 is slowly injected into the lithium-ion battery 3, improving the effect of the battery cell electrode sheet infiltrating and absorbing the electrolyte, so that the electrolyte is thoroughly infiltrated to avoid the phenomenon of liquid bubbling. In this embodiment, the first pressure is 0 KPa, and the pressure-maintaining time at the first pressure is 60-65 s; the second positive pressure is 180 KPa, and the pressure-maintaining time at the second pressure is 30-35 s; the third pressure is 400 KPa, and the pressure-maintaining time at the third pressure is 30-35 s; the target positive pressure is ≥650 kPa, and the pressure-maintaining time at the target pressure is ≥250 s.

[0028] S4. Repeat steps S2 and S3 several times.

[0029] S5. Decompression, completion of liquid injection. In this embodiment, the decompression time is set to 42s. Within the specified time, the device is connected to the external air pressure valve through the static cover 1, and the air pressure valve is opened to complete the decompression. After the decompression, the real-time pressure of the static cover 1 is displayed as 0.

[0030] In this embodiment, the lithium-ion battery 3 and the sleeve cup 2 are simultaneously evacuated or pressurized in the pressurized static unit, and isobaric conditions are formed inside and outside the battery; the electrolyte is transferred from the sleeve cup 2 to the lithium-ion battery 3 by high pressure ≥650KPa. This process greatly improves the electrolyte absorption efficiency and infiltration effect, as well as the uniformity of electrolyte absorption. In this embodiment, the injection process parameters such as vacuum time, pressurization time, and pressure holding time are adjustable, and the number of cycles can be set according to actual conditions to correspond to the injection static parameters of different cavities.

[0031] The present invention will be further described below in conjunction with specific embodiments.

[0032] Example 1 This embodiment provides a lithium ion battery injection method, which includes the following steps: S1. Connect the cup 2 filled with electrolyte to the injection port of the lithium-ion battery 3, and place the cup 2 and the lithium-ion battery 3 into the stationary cover 1.

[0033] like Figure 2 As shown, the electrolyte with a large amount of liquid injection in the injection station is preferentially injected into multiple sets of cups 2 for storage at one time, and the tray 4 containing lithium-ion batteries 3 and the sets of cups 2 are placed in the static cover 1 together by a stacking trolley. Each battery tray 3 contains 32 lithium-ion batteries 3, and the battery tray 3 and the sets of cups 2 are placed in the sealed space of the static cover 1 of the pressurized static unit by a stacking trolley, and each static cover 1 contains 64 lithium-ion batteries 3.

[0034] S2. Evacuate the stationary cover 1 and maintain the pressure at the target vacuum degree.

[0035] In this embodiment, the vacuuming time is ≤40s, the target vacuum degree is -90±10KPa, and the vacuum holding time is 60s.

[0036] S3. Perform stepwise positive pressure charging on the stationary cover 1 and maintain the pressure at the target positive pressure.

[0037] In this embodiment, a multi-step stepped positive pressure injection process is adopted: the static cover is filled with positive pressure to 0 KPa and the pressure is maintained for 60 seconds; then the static cover 1 is filled with positive pressure to 180 KPa and the pressure is maintained for 30 seconds; then the static cover 1 is filled with positive pressure to 400 and the pressure is maintained for 30 seconds; then the static cover 1 is filled with positive pressure to the target positive pressure ≥ 650 KPa, and the pressure is maintained at the target positive pressure for ≥ 250 seconds.

[0038] S4. Repeat steps S2 and S3 three times in sequence.

[0039] S5. Break the pressure and complete the injection.

[0040] Example 2 This embodiment provides a lithium ion battery injection method, which includes the following steps: S1. Connect the sleeve cup 2 filled with electrolyte to the injection port of the lithium-ion battery 3, and place the sleeve cup and the lithium-ion battery in the same stationary cover 1.

[0041] like Figure 2 As shown, the electrolyte with a large amount of liquid injection in the injection station is preferentially injected into multiple sets of cups 2 for storage at one time, and the tray 4 containing lithium-ion batteries 3 and the sets of cups 2 are placed in the static cover 1 together by a stacking trolley. Each battery tray 4 contains 32 lithium-ion batteries 3, and the battery tray 4 and the sets of cups 2 are placed in the sealed space of the static cover 1 of the pressurized static unit by a stacking trolley, and each static cover 1 contains 64 lithium-ion batteries 3.

[0042] S2. Evacuate the stationary cover 1 and maintain the pressure at the target vacuum degree.

[0043] In this embodiment, the vacuuming time is ≤40s, the target vacuum degree is -90±10KPa, and the vacuum holding time is 60s.

[0044] S3. Perform stepwise positive pressure charging on the stationary cover 1 and maintain the pressure at the target positive pressure.

[0045] In this embodiment, a one-step positive pressure injection process is adopted: the static cover is filled with positive pressure to 0 KPa and the pressure is maintained for 180 seconds; then the static cover 1 is filled with positive pressure to a target positive pressure ≥ 680 KPa, and the pressure is maintained at the target positive pressure for ≥ 240 seconds.

[0046] S4. Repeat steps S2 and S3 twice.

[0047] S5. Break the pressure and complete the injection.

[0048] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0049] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A lithium ion battery injection method, characterized in that: It includes the following steps: S1. Connect the cup filled with electrolyte to the injection port of the lithium-ion battery, and place the cup and the lithium-ion battery in the same sealed space; S2. Evacuate the sealed space and maintain pressure at the target vacuum degree; S3. The sealed space is charged with positive pressure in a stepped manner and maintained at the target positive pressure; S4. Repeat steps S2 and S3 several times; S5. Break the pressure and complete the injection.

2. The lithium ion battery injection method according to claim 1, characterized in that: In step S2, the target vacuum degree is -90±10 KPa, and the pressure holding time at the target vacuum degree is 60-65 s.

3. The lithium ion battery injection method according to claim 1, characterized in that: In step S2, the vacuuming time is ≤40s.

4. The lithium ion battery injection method according to claim 1, characterized in that: In step S3, the stepwise positive pressure charging includes: charging the sealed space with positive pressure to a first pressure and maintaining the pressure; then charging the sealed space with positive pressure to a second positive pressure and maintaining the pressure, the second positive pressure is greater than the first positive pressure; then charging the sealed space with positive pressure to a third positive pressure and maintaining the pressure, the third positive pressure is greater than the second positive pressure; then charging the sealed space with positive pressure to a target positive pressure and maintaining the pressure, the target positive pressure is greater than the third positive pressure.

5. The lithium ion battery injection method according to claim 4, characterized in that: The first pressure is 0 KPa, and the pressure-holding time at the first pressure is 60-65 s; and / or, the second positive pressure is 180 KPa, and the pressure-holding time at the second pressure is 30-35 s; and / or, the third pressure is 400 KPa, and the pressure-holding time at the third pressure is 30-35 s; and / or, the target positive pressure is ≥650 kPa, and the pressure-holding time at the target pressure is ≥250 s.

6. The lithium ion battery injection method according to claim 5, characterized in that: In step S4, steps S2 and S3 are repeated three times in sequence.

7. The lithium ion battery injection method according to claim 1, characterized in that: In step S3, the stepwise positive pressure charging includes: charging the sealed space with positive pressure to a first pressure and maintaining the pressure; and then charging the sealed space with positive pressure to a target positive pressure and maintaining the pressure.

8. The lithium ion battery injection method according to claim 7, characterized in that: The first pressure is 0 KPa, and the pressure-maintaining time at the first pressure is 180-185 s; and / or the target positive pressure is ≥ 680 kPa, and the pressure-maintaining time at the target positive pressure is ≥ 240 s.

9. The lithium ion battery injection method according to claim 8, characterized in that: In step S4, steps S2 and S3 are repeated twice in sequence.

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