A high-efficiency lithium-ion battery electrolyte filling method

Abstract

The invention discloses a high-efficiency lithium-ion battery injection method, comprising the following steps: S1: removing excessive water inside the battery by heating, then preheating the electrolyte, and cooling the heated battery; S2: placing the battery in a vacuum chamber of an injection machine, evacuating the chamber of the injection machine, and when the vacuum degree reaches a predetermined value, stopping the vacuuming and injecting the battery, and when the injection amount is reached, stopping the injection, and maintaining the vacuum degree for a period of time; the advantages of the present invention are that the residual temperature of the battery after baking is utilized, and there is no need to reduce the temperature to room temperature and then heat it up, thus saving process time, preheating the electrolyte, and always maintaining a certain temperature before injecting it into the battery, and completing the battery injection through a breathing process, thereby improving the injection efficiency and ensuring the injection effect, shortening the battery manufacturing cycle, ensuring good infiltration of the battery electrode interface, and facilitating the stability of the chemical system during formation.

Description

Technical Field

[0001] The invention specifically relates to a high-efficiency lithium-ion battery injection method. Background Art

[0002] After the lithium-ion battery is assembled, it needs to be injected. The electrolyte in the lithium-ion battery is a very important component. It is responsible for the ion transmission in the battery, and can also help dissipate heat and protect the battery. Injection can ensure the normal chemical reaction inside the battery. The injection process can effectively prevent safety issues such as battery overheating, short circuit and leakage.

[0003] The injection process has gone through several generations of development, including normal pressure injection, negative pressure injection, and isobaric injection, all of which are aimed at increasing the electrode wetting speed, thereby improving production efficiency. Negative pressure injection is the mainstream injection method, and even the popular isobaric injection method uses differential pressure to first inject the electrolyte into the battery cell, and then uses the high-pressure isobaric principle to do a static cycle to increase the electrolyte infiltration speed.

[0004] The higher the margin of the battery, the more difficult it is to inject the battery, and the longer the wetting time after injection, which prolongs the entire production cycle of the battery and increases the production cost. The wetting time after current battery injection is generally greater than 24 hours. Poor wetting can also lead to large internal resistance of the battery, black spots and lithium precipitation, and other abnormalities, causing battery safety problems. For this reason, we propose a high-efficiency lithium-ion battery injection method. Summary of the invention

[0005] The object of the present invention is to provide a high-efficiency lithium-ion battery injection method to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a high-efficiency lithium-ion battery injection method, comprising the following steps:

[0007] S1: Remove excess water inside the battery by heating, then preheat the electrolyte and cool the heated battery;

[0008] S2: The battery is placed in the vacuum chamber of the liquid injection machine, and the liquid injection machine closes the chamber to evacuate the vacuum. When the vacuum reaches a predetermined value, the vacuum is stopped and the battery is injected. When the injection volume is reached, the injection is stopped and the vacuum is maintained for a period of time.

[0009] S3: Inject inert gas into the vacuum chamber of the liquid injection machine. Stop injecting when the vacuum degree in the chamber reaches -10Kpa and keep it for a while.

[0010] S4: Evacuate the vacuum chamber of the liquid injection machine again to above -95Kpa, stop evacuating, and keep it for a while;

[0011] S5: repeat steps S3 and S4 2 to 4 times, then release the pressure in the vacuum chamber, remove the battery, and complete the liquid injection;

[0012] S6: Place the battery after liquid injection in a high temperature room to soak for a period of time, and then send the battery to the formation process for formation.

[0013] Preferably, in S1:

[0014] The excess moisture inside the battery is removed by placing the battery in an oven for baking. The baking is a vertical contact baking. After baking, the moisture content of the battery is ≤150ppm.

[0015] Preferably, in S1:

[0016] The battery temperature after cooling is 35℃±3℃.

[0017] Preferably, in S1:

[0018] The electrolyte preheating temperature is 30-35°C, and the electrolyte temperature is kept constant before entering the battery cell.

[0019] Preferably, in S2:

[0020] The predetermined vacuum degree of the vacuum pumping is at least -95Kpa, the injection volume is 413±3g, the vacuum leakage rate of the vacuum chamber is not greater than 30S / Kpa, and the time for maintaining the vacuum degree is 30S-60S.

[0021] Preferably, in S3:

[0022] The holding time is 30S-60S.

[0023] Preferably, in S4:

[0024] The holding time is 30S-60S.

[0025] Preferably, in S5:

[0026] The pressure relief method reduces the risk of electrolyte splashing and contaminating the cavity by step-by-step pressure reduction.

[0027] Preferably, in S6:

[0028] The temperature of the high temperature room is 45°C-60°C, and the static soaking time is 12 hours.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The advantages of the present invention are that the residual temperature after the battery is baked is utilized, and there is no need to cool it down to room temperature and then heat it up, which saves process time and preheats the electrolyte. The electrolyte is always kept at a certain temperature before being injected into the battery, and the battery injection is completed through a breathing process, which improves the injection efficiency while ensuring the injection effect, shortens the battery manufacturing cycle, ensures that the battery electrode interface is well infiltrated, and is beneficial to the stability of the chemical system during formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure is a schematic diagram of the process flow of the lithium ion battery injection method of the present invention. DETAILED DESCRIPTION

[0032] 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.

[0033] Example 1

[0034] See also Figure 1 The present invention provides a technical solution: a high-efficiency lithium-ion battery injection method, comprising the following steps:

[0035] S1: Remove excess water inside the battery by heating to avoid excessive water in the battery that will affect the battery's performance and safety. Then preheat the electrolyte and cool the heated battery to ensure that the electrolyte and battery are at the right temperature during the injection process, which helps improve the electrolyte's penetration efficiency.

[0036] S2: Place the battery into the vacuum chamber of the liquid injection machine. The liquid injection machine closes the chamber to evacuate the air and moisture inside the battery and create a good environment for liquid injection. When the vacuum degree reaches a predetermined value, stop evacuating the battery and inject liquid into it, which helps to ensure that the electrolyte penetrates evenly into the battery. When the injection volume is reached, stop injecting liquid and maintain the vacuum degree for a period of time.

[0037] S3: Injecting inert gas into the vacuum chamber of the liquid injection machine is to replace the harmful gas that may remain in the liquid injection process and protect the battery from oxidation. When the vacuum degree in the chamber reaches -10Kpa, stop injecting and keep it for a while;

[0038] S4: Evacuate the vacuum chamber of the liquid injection machine again to above -95Kpa, stop evacuating, and keep it for a while;

[0039] S5: Repeat steps S3 and S4 2 to 4 times. Multiple vacuuming and restoring normal pressure help ensure that the electrolyte completely penetrates every corner of the battery. Then, the vacuum chamber is depressurized, the battery is removed, and the electrolyte injection is completed.

[0040] S6: Place the battery after injection in a high temperature room for a period of time. Placing the battery in a high temperature environment helps to further promote the penetration and uniform distribution of the electrolyte. It is also a preparatory step before battery formation. The battery can then be sent to the formation process for formation.

[0041] Preferably, in S1:

[0042] The excess water inside the battery is removed by placing the battery in an oven for baking. The baking is vertical contact baking. After baking, the water content of the battery is ≤150ppm.

[0043] The battery temperature after cooling is 35℃±3℃;

[0044] The electrolyte preheating temperature is 30-35°C, and the electrolyte temperature is kept constant before entering the battery cell.

[0045] Preferably, in S2:

[0046] The preset vacuum degree of the vacuum pump is at least -95Kpa, the injection volume is 413±3g, the vacuum leakage rate of the vacuum chamber is not greater than 30S / Kpa, and the vacuum degree is maintained for 30S-60S in seconds.

[0047] Preferably, in S3: the holding time is 30S-60S.

[0048] Preferably, in S4: the holding time is 30S-60S.

[0049] Preferably, in S5: the pressure relief method is to reduce the electrolyte splashing and contaminating the cavity by reducing the pressure in a step-by-step manner.

[0050] Preferably, in S6: the temperature of the high temperature room is 45°C-60°C, and the static soaking time is 12 hours.

[0051] Example 2

[0052] like Figure 1 As shown: the specification of the lithium-ion battery used in this embodiment is 118Ah;

[0053] A lithium-ion battery injection method comprises the following steps:

[0054] S1: The assembled peripheral welded battery is placed in an oven and baked in a vertical contact manner to remove excess moisture inside the battery, so that the moisture content of each component inside the battery is ≤150ppm;

[0055] S2: preheat the electrolyte to 30°C and keep the temperature of the electrolyte unchanged before entering the battery cell;

[0056] S3: Cool the baked battery to 35°C. During the cooling process, the temperature uniformity of the entire oven must be ensured.

[0057] S4: Take out the battery from the oven and put it into the vacuum chamber of the liquid filling machine. The liquid filling machine closes the chamber and evacuates the vacuum. The batteries are taken out from the oven and enter the vacuum chamber of the liquid filling machine at the same time to ensure the consistency of the cells in the same batch.

[0058] S5: When the vacuum degree reaches -95Kpa or higher, stop vacuuming and inject liquid into the battery. When the set injection volume reaches 413±3g, stop injecting liquid and maintain the pressure at -95Kpa for 45S.

[0059] S6: Inject nitrogen or other inert gas into the vacuum chamber of the liquid injection machine. When the vacuum degree in the chamber reaches -10Kpa, stop nitrogen injection and maintain for 45S.

[0060] S7: Evacuate the vacuum chamber of the liquid injection machine again to above -95Kpa, stop evacuating, and maintain for 45S;

[0061] S8: Repeat steps S6 and S7 for 3 times, then slowly release the pressure in a gradient manner, open the vacuum chamber of the liquid injection machine, take out the battery, and complete the liquid injection;

[0062] S9: Place the battery after injection in a high temperature room at 45°C for 12 hours, and then send the battery to the formation process for formation.

[0063] Example 3

[0064] The specification of the lithium-ion battery used in this embodiment is 118Ah; the difference from embodiment 1 is that the parameters are different;

[0065] A lithium-ion battery injection method comprises the following steps:

[0066] S1: The assembled peripheral welded battery is placed in an oven and baked in a vertical contact manner to remove excess moisture inside the battery, so that the moisture content of each component inside the battery is ≤150ppm;

[0067] S2: preheat the electrolyte to 35°C and keep the temperature of the electrolyte unchanged before entering the battery cell;

[0068] S3: Cool the baked battery to 35°C. During the cooling process, the temperature uniformity of the entire oven must be ensured.

[0069] S4: Take out the battery from the oven and put it into the vacuum chamber of the liquid filling machine. The liquid filling machine closes the chamber and evacuates the vacuum. The batteries are taken out from the oven and enter the vacuum chamber of the liquid filling machine at the same time to ensure the consistency of the cells in the same batch.

[0070] S5: When the vacuum degree reaches -95Kpa or higher, stop pumping and inject liquid into the battery. When the set injection volume reaches 413±3g, stop injecting liquid and maintain the pressure at -95Kpa for 60S.

[0071] S6: Inject nitrogen or other inert gas into the vacuum chamber of the liquid injection machine. When the vacuum degree in the chamber reaches -10Kpa, stop nitrogen injection and maintain for 60S.

[0072] S7: Evacuate the vacuum chamber of the liquid injection machine again to above -95Kpa, stop evacuating, and maintain for 60S;

[0073] S8: Repeat steps S6 and S7 twice, slowly release the pressure in a gradient manner, open the vacuum chamber of the liquid injection machine, take out the battery, and complete the liquid injection;

[0074] S9: Place the battery after injection in a high temperature room at 45°C for 12 hours, and then send the battery to the formation process for formation.

[0075] Example 4

[0076] like Figure 1 As shown: the specification of the lithium-ion battery used in this embodiment is 118Ah;

[0077] A lithium-ion battery injection method comprises the following steps:

[0078] S1: The assembled peripheral welded battery is placed in an oven and baked in a vertical contact manner to remove excess moisture inside the battery, so that the moisture content of each component inside the battery is ≤150ppm;

[0079] S2: preheat the electrolyte to 35°C and keep the temperature of the electrolyte unchanged before entering the battery cell;

[0080] S3: Cool the baked battery to 40°C. During the cooling process, the temperature uniformity of the entire oven must be ensured.

[0081] S4: Take out the battery from the oven and put it into the vacuum chamber of the liquid filling machine. The liquid filling machine closes the chamber and evacuates the vacuum. The batteries are taken out from the oven and enter the vacuum chamber of the liquid filling machine at the same time to ensure the consistency of the cells in the same batch.

[0082] S5: When the vacuum degree reaches -95Kpa or higher, stop pumping and inject liquid into the battery. When the set injection volume reaches 413±3g, stop injecting liquid and maintain the pressure at -95Kpa for 30S.

[0083] S6: Inject nitrogen or other inert gas into the vacuum chamber of the liquid injection machine. When the vacuum degree in the chamber reaches -10Kpa, stop injecting nitrogen and keep it for 30S.

[0084] S7: Evacuate the vacuum chamber of the liquid injection machine again to above -95Kpa, stop evacuating, and maintain for 30S;

[0085] S8: Repeat steps S6 and S7 for 4 times, then slowly release the pressure in a gradient manner, open the vacuum chamber of the liquid injection machine, take out the battery, and complete the liquid injection;

[0086] S9: Place the battery after injection in a high temperature room at 45°C for 24 hours, and then send the battery to the formation process for formation.

[0087] Comparative Example 1

[0088] The specification of the lithium-ion battery used in this comparative example is 118Ah; the difference from the above-mentioned Examples 2 to 4 is that: the temperature of the electrolyte in step S2 is 23°C at room temperature; in step S3, the temperature of the battery core drops to 23°C at room temperature;

[0089] A lithium-ion battery injection method comprises the following steps:

[0090] S1: The assembled peripheral welded battery is placed in an oven and baked in a vertical contact manner to remove excess moisture inside the battery, so that the moisture content of each component inside the battery is ≤150ppm;

[0091] S2: preheat the electrolyte to 23°C and keep the temperature of the electrolyte unchanged before entering the battery cell;

[0092] S3: Cool the baked batteries to 23°C. During the cooling process, the temperature uniformity of the entire oven must be ensured.

[0093] S4: Take out the battery from the oven and put it into the vacuum chamber of the liquid filling machine. The liquid filling machine closes the chamber and evacuates the vacuum. The batteries are taken out from the oven and enter the vacuum chamber of the liquid filling machine at the same time to ensure the consistency of the cells in the same batch.

[0094] S5: When the vacuum degree reaches -95Kpa or higher, stop vacuuming and inject liquid into the battery. When the set injection volume reaches 413±3g, stop injecting liquid and maintain the pressure at -95Kpa for 45S.

[0095] S6: Inject nitrogen or other inert gas into the vacuum chamber of the liquid injection machine. When the vacuum degree in the chamber reaches -10Kpa, stop nitrogen injection and maintain for 45S.

[0096] S7: Evacuate the vacuum chamber of the liquid injection machine again to above -95Kpa, stop evacuating, and maintain for 45S;

[0097] S8: Repeat steps S6 and S7 for 3 times, slowly release the pressure in a gradient manner, open the vacuum chamber of the liquid injection machine, take out the battery, and complete the liquid injection;

[0098] S9: Place the battery after injection in a high temperature room at 45°C for 12 hours, and then send the battery to the formation process for formation.

[0099] Comparative Example 2

[0100] The specification of the lithium-ion battery used in this comparative example is 118Ah; the difference from the above-mentioned embodiments 2 to 4 is that: the battery pressure holding time in step S5 is 5 minutes; there are no breathing steps such as S6, S7, and S8;

[0101] A lithium-ion battery injection method comprises the following steps:

[0102] S1: The assembled peripheral welded battery is placed in an oven and baked in a vertical contact manner to remove excess moisture inside the battery, so that the moisture content of each component inside the battery is ≤150ppm;

[0103] S2: preheat the electrolyte to 23°C and keep the temperature of the electrolyte unchanged before entering the battery cell;

[0104] S3: Cool the baked batteries to 23°C. During the cooling process, the temperature uniformity of the entire oven must be ensured.

[0105] S4: Take out the battery from the oven and put it into the vacuum chamber of the liquid filling machine. The liquid filling machine closes the chamber and evacuates the vacuum. The batteries are taken out from the oven and enter the vacuum chamber of the liquid filling machine at the same time to ensure the consistency of the cells in the same batch.

[0106] S5: When the vacuum degree reaches -95Kpa or higher, stop vacuuming and inject liquid into the battery. When the set injection volume reaches 413±3g, stop injecting liquid and maintain the pressure at -95Kpa for 5 minutes.

[0107] S6: Place the battery after injection in a high temperature room at 45°C for 12 hours, and then send the battery to the formation process for formation.

[0108] Experiment: 118Ah lithium-ion batteries produced in the same batch were randomly divided into 5 groups of batteries with the same sample size, and were injected and left to stand according to the methods described in Examples 2 to 4 and Comparative Examples 1 to 2. The same number of batteries were selected from each group and disassembled after infiltration, fully charged and tested for performance in the same way.

[0109] The infiltration and disassembly focus on the wetting effect of the electrode diaphragm and the amount of free electrolyte; the full-charge disassembly focuses on the appearance of the negative electrode and the black spot lithium precipitation; the performance test focuses on the first effect, the first discharge capacity, and the battery internal resistance.

[0110] The test results are shown in Tables 1 to 3:

[0111] Table 1 Disassembly results after infiltration

[0112]

[0113] Table 2 Full power disassembly results

[0114] Negative electrode appearance Negative state Residual electrolyte amount Example 2 Uniform golden yellow No lithium deposition Small amount Example 3 Uniform golden yellow No lithium deposition Small amount Example 4 Uniform golden yellow No lithium deposition Small amount Comparative Example 1 Slight dark spots No lithium deposition less Comparative Example 2 Dark spots Slight lithium deposition More

[0115] Table 3 Performance test results

[0116]

[0117]

[0118] It can be seen from Tables 1 to 3 that the battery wetting effect obtained by the liquid injection method adopted by the present invention is better, the process time is shorter, and the interface state and performance have obvious advantages over the comparative example.

[0119] 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 high-efficiency lithium-ion battery injection method, characterized in that: The following steps are involved: S1: Remove excess water inside the battery by heating, then preheat the electrolyte and cool the heated battery; S2: The battery is placed in the vacuum chamber of the liquid injection machine, and the liquid injection machine closes the chamber to evacuate the vacuum. When the vacuum reaches a predetermined value, the vacuum is stopped and the battery is injected. When the injection volume is reached, the injection is stopped and the vacuum is maintained for a period of time. S3: Inject inert gas into the vacuum chamber of the liquid injection machine. Stop injecting when the vacuum degree in the chamber reaches -10Kpa and keep it for a period of time T1; S4: Evacuate the vacuum chamber of the liquid injection machine again to above -95Kpa, stop evacuating, and maintain for a period of time T2; S5: repeat steps S3 and S4 2 to 4 times, then release the pressure in the vacuum chamber, remove the battery, and complete the liquid injection; S6: Place the battery after liquid injection in a high temperature room to soak for a period of time, and then send the battery to the formation process for formation; In said S1: The battery temperature after cooling is 35℃±3℃; In said S1: The electrolyte preheating temperature is 30-35°C, and the electrolyte temperature is kept constant before entering the battery cell.

2. A high-efficiency lithium-ion battery injection method according to claim 1, characterized in that: In said S1: The excess moisture inside the battery is removed by placing the battery in an oven for baking. The baking is a vertical contact baking. After baking, the moisture content of the battery is ≤150ppm.

3. A high-efficiency lithium-ion battery injection method according to claim 1, characterized in that: In said S2: The predetermined vacuum degree of the vacuum pumping is at least -95Kpa, the injection volume is 413±3g, the vacuum leakage rate of the vacuum chamber is not greater than 30S / Kpa, and the time for maintaining the vacuum degree is 30S-60S.

4. A high-efficiency lithium-ion battery injection method according to claim 1, characterized in that: In the S3: The T1 is 30S-60S.

5. A high-efficiency lithium-ion battery injection method according to claim 1, characterized in that: In said S4: The T2 is 30S-60S.

6. A high-efficiency lithium-ion battery injection method according to claim 1, characterized in that: In said S5: The pressure relief is performed by step-by-step pressure reduction to reduce the risk of electrolyte splashing and contaminating the cavity.

7. A high-efficiency lithium-ion battery injection method according to claim 1, characterized in that: In said S6: The temperature of the high temperature room is 45°C-60°C, and the static soaking time is 12 hours.

Images