A kind of injection process for improving the cycle life of soft package energy storage lithium ion battery

Abstract

This invention discloses a liquid injection process for improving the cycle life of pouch-type lithium-ion batteries, comprising the following steps: S1. First liquid injection; S2. Pretreatment; S3. Pre-charge formation; S4. Second liquid injection; S5. High-temperature standing wetting; S6. Formation; S7. Temperature and pressure standing; S8. Third liquid injection. Through this multi-step liquid injection process, the chemical reaction consumption of lithium salts and electrolyte additives during the formation of pouch-type lithium-ion batteries can be effectively compensated, providing sufficient active lithium ions to the cell in the lithium-ion electrolyte again. These lithium ions can be repeatedly extracted and inserted during the charging and discharging process of the positive and negative electrodes of the pouch-type lithium-ion battery, thus improving the battery's cycle life.

Description

Technical Field

[0001] This invention relates to the field of liquid injection technology, and in particular to a liquid injection process for improving the cycle life of soft-pack lithium-ion batteries. Background Technology

[0002] The conventional electrolyte filling method for existing soft-pack lithium-ion batteries is a single filling process, followed by vacuuming and sealing of the cell. The cell is then left to stand at room temperature to allow the electrolyte to penetrate the electrodes before being charged. This process is repeated with vacuuming, degassing, and sealing. This traditional method is not conducive to the long cycle life performance of soft-pack lithium-ion batteries. Summary of the Invention

[0003] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a liquid injection process to improve the cycle life of soft-pack energy storage lithium-ion batteries. The main innovation is that...

[0004] This invention also provides a liquid injection process for improving the cycle life of pouch-type lithium-ion batteries, comprising the following steps:

[0005] S1. First electrolyte injection: Inject 50%-90% of the total electrolyte volume into the battery cell;

[0006] S2. Pretreatment: Pressurize the inside of the battery for 5-10 seconds, repeat 4-10 times, then remove the vacuum and seal the edges. Then, place the battery in an insulated box for high-temperature static immersion for 30-120 minutes.

[0007] S3. Pre-charge formation: The SOC of the formation charge is 20%-90%;

[0008] S4. Second electrolyte injection: Inject half of the remaining electrolyte volume, pressurize for 5-10 seconds, repeat 4-10 times, and then vacuum and seal the battery.

[0009] S5. High-temperature static wetting: Place the battery in an insulated box and immerse it for 30-90 minutes;

[0010] S6. Formation: The state of charge (SOC) of the formation charge is 3-20%;

[0011] S7. Temperature and Pressure Settling: Place the battery in a temperature and pressure settling box and let it stand for 1-4 hours;

[0012] S8. Third injection: Fill the remaining amount of total injection volume, then vacuum and seal the edges.

[0013] According to the present invention, an electrolyte injection process for improving the cycle life of a soft-pack energy storage lithium-ion battery is provided, wherein the electrolyte is 1.0-1.1M LiPF6, the solvent is EC / DEC / EMC = 1:1:1, and the additive is VC.

[0014] According to the present invention, an injection process for improving the cycle life of a soft-pack energy storage lithium-ion battery is provided, wherein the positive electrode material of the lithium-ion battery is lithium iron phosphate positive electrode material, and the negative electrode adopts a traditional graphite negative electrode.

[0015] According to the liquid injection process for improving the cycle life of soft-pack energy storage lithium-ion batteries provided by the present invention, the pressure applied in S2 and S4 is 0.3-1 MPa.

[0016] According to the electrolyte injection process for improving the cycle life of pouch-type lithium-ion batteries provided by the present invention, the temperature inside the insulation box is 25℃-65℃.

[0017] According to the present invention, an electrolyte injection process for improving the cycle life of a soft-pack energy storage lithium-ion battery is provided, wherein the formation time is 1-5 hours and the formation current is 0.002-5C.

[0018] According to the present invention, a liquid injection process for improving the cycle life of a soft-pack energy storage lithium-ion battery is provided, wherein the temperature inside the heat preservation and pressure preservation box is 25℃-65℃ and the pressure is 0.1-0.8Mpa.

[0019] Beneficial effects:

[0020] 1. This invention, by repeatedly pressurizing and releasing the electrolyte after injection, allows the electrolyte to quickly penetrate into the battery and its contents, and reduces the subsequent settling and wetting time, thereby improving the efficiency of battery electrolyte injection.

[0021] 2. This invention employs a three-stage electrolyte injection process. After each injection, air is removed and the electrolyte is sealed. This multi-step injection method effectively compensates for the chemical reaction consumption of lithium salts and electrolyte additives during the formation of the soft-pack lithium-ion battery. It replenishes the lithium-ion electrolyte with sufficient active lithium ions for the cell, allowing these ions to repeatedly extract and re-enter during the charging and discharging processes at the positive and negative electrodes of the soft-pack lithium-ion battery. This multi-step injection method significantly improves the cycle life of the soft-pack lithium-ion battery. Detailed Implementation

[0022] This section will describe in detail specific embodiments of the present invention. The description of the preferred embodiments of the present invention in the supplementary specification text enables people to intuitively and vividly understand each technical feature and overall technical solution of the present invention, but it should not be construed as a limitation on the scope of protection of the present invention.

[0023] An embodiment of the present invention provides a liquid injection process for improving the cycle life of soft-pack lithium-ion batteries, which includes the following steps:

[0024] S1. First electrolyte injection: Inject 50%-90% of the total electrolyte volume into the battery cell;

[0025] S2. Pretreatment: Pressurize the inside of the battery for 5-10 seconds, repeat 4-10 times, then remove the vacuum and seal the edges. Then, place the battery in an insulated box for high-temperature static immersion for 30-120 minutes.

[0026] S3. Pre-charge formation: The SOC of the formation charge is 20%-90%;

[0027] S4. Second electrolyte injection: Inject half of the remaining electrolyte volume, pressurize for 5-10 seconds, repeat 4-10 times, and then vacuum and seal the battery.

[0028] S5. High-temperature static wetting: Place the battery in an insulated box and immerse it for 30-90 minutes;

[0029] S6. Formation: The state of charge (SOC) of the formation charge is 3-20%;

[0030] S7. Temperature and Pressure Settling: Place the battery in a temperature and pressure settling box and let it stand for 1-4 hours;

[0031] S8. Third injection: Fill the remaining amount of total injection volume, then vacuum and seal the edges.

[0032] The electrolyte is 1.0-1.1M LiPF6, with a solvent ratio of EC / DEC / EMC = 1:1:1 and the additive is VC.

[0033] The positive electrode material of the lithium-ion battery is lithium iron phosphate, and the negative electrode uses traditional graphite.

[0034] The pressure applied in S2 and S4 is 0.3-1 MPa.

[0035] The temperature inside the insulated box is 25℃-65℃.

[0036] The formation time is 1-5 hours, and the formation current is 0.002-5C.

[0037] The temperature inside the insulation and pressure chamber is 25-65°C, and the pressure is 0.1-0.8 MPa.

[0038] Comparative Example 1:

[0039] A liquid injection process for improving the cycle life of pouch-type lithium-ion batteries includes:

[0040] S1. First electrolyte injection: Inject 50%-90% of the total electrolyte volume into the battery cell;

[0041] S2. Pretreatment: Pressurize the inside of the battery for 5-10 seconds, repeat 4-10 times, and then place the battery in an insulated box for high-temperature static immersion for 30-120 minutes.

[0042] S3. Pre-charge formation: The SOC of the formation charge is 20%-90%;

[0043] S4. Second injection: Inject half of the remaining volume of electrolyte, pressurize for 5-10 seconds, and repeat 4-10 times.

[0044] S5. High-temperature static wetting: Place the battery in an insulated box and immerse it for 30-90 minutes;

[0045] S6. Formation: The state of charge (SOC) of the formation charge is 3-20%;

[0046] S7. Temperature and Pressure Settling: Place the battery in a temperature and pressure settling box and let it stand for 1-4 hours;

[0047] S8. Third injection: Fill the remaining amount of total injection volume, then vacuum and seal the edges.

[0048] The electrolyte is 1.0-1.1M LiPF6, with a solvent ratio of EC / DEC / EMC = 1:1:1 and the additive is VC.

[0049] The positive electrode material of the lithium-ion battery is lithium iron phosphate, and the negative electrode uses traditional graphite.

[0050] The pressure applied in S2 and S4 is 0.3-1 MPa.

[0051] The temperature inside the insulated box is 25℃-65℃.

[0052] The formation time is 1-5 hours, and the formation current is 0.002-5C.

[0053] The temperature inside the insulation and pressure chamber is 25-65°C, and the pressure is 0.1-0.8 MPa.

[0054] Comparative Example 2:

[0055] A liquid injection process for improving the cycle life of pouch-type lithium-ion batteries includes:

[0056] S1. First electrolyte injection: Inject 50%-90% of the total electrolyte volume into the battery cell;

[0057] S2. Pretreatment: Vacuum the battery and seal the edges. Then, place the battery in an insulated box and immerse it in high temperature for 1-4 hours.

[0058] S3. Pre-charge formation: The SOC of the formation charge is 20%-90%;

[0059] S4. Second electrolyte injection: Inject half of the remaining electrolyte volume, evacuate the battery and seal the edges;

[0060] S5. High-temperature static wetting: Place the battery in an insulated box and immerse it for 1-4 hours;

[0061] S6. Formation: The state of charge (SOC) of the formation charge is 3-20%;

[0062] S7. Temperature and Pressure Settling: Place the battery in a temperature and pressure settling box and let it stand for 1-4 hours;

[0063] S8. Third injection: Fill the remaining amount of total injection volume, then vacuum and seal the edges.

[0064] The electrolyte is 1.0-1.1M LiPF6, with a solvent ratio of EC / DEC / EMC = 1:1:1 and the additive is VC.

[0065] The positive electrode material of the lithium-ion battery is lithium iron phosphate, and the negative electrode uses traditional graphite.

[0066] The pressure applied in S2 and S4 is 0.3-1 MPa.

[0067] The temperature inside the insulated box is 25℃-65℃.

[0068] The formation time is 1-5 hours, and the formation current is 0.002-5C.

[0069] The temperature inside the insulation and pressure chamber is 25-65°C, and the pressure is 0.1-0.8 MPa.

[0070] Comparative Example 3:

[0071] A liquid injection process for improving the cycle life of pouch-type lithium-ion batteries includes:

[0072] S1. First electrolyte injection: Inject 50%-90% of the total electrolyte volume into the battery cell;

[0073] S2. Pretreatment: Pressurize the inside of the battery for 5-10 seconds, repeat 4-10 times, then remove the vacuum and seal the edges. Then, place the battery in an insulated box for high-temperature static immersion for 30-120 minutes.

[0074] S3. Pre-charge formation: The SOC of the formation charge is 20%-90%;

[0075] S4. Second electrolyte injection: Inject the electrolyte into the remaining total amount of electrolyte, pressurize for 5-10 seconds, repeat 4-10 times, and then vacuum and seal the battery.

[0076] S5. High-temperature static wetting: Place the battery in an insulated box and immerse it for 30-90 minutes;

[0077] S6. Formation: The state of charge (SOC) of the formation charge is 3-20%.

[0078] The electrolyte is 1.0-1.1M LiPF6, with a solvent ratio of EC / DEC / EMC = 1:1:1 and the additive is VC.

[0079] The positive electrode material of the lithium-ion battery is lithium iron phosphate, and the negative electrode uses traditional graphite.

[0080] The pressure applied in S2 and S4 is 0.3-1 MPa.

[0081] The temperature inside the insulated box is 25℃-65℃.

[0082] The formation time is 1-5 hours, and the formation current is 0.002-5C.

[0083] The temperature inside the insulation and pressure chamber is 25-65°C, and the pressure is 0.1-0.8 MPa.

[0084]

[0085] Five groups of the above proportions were conducted, and the average value of the experimental data was taken. As can be seen from the above data, the present invention can shorten the liquid injection time, accelerate the formation of the battery, and increase the number of cycles.

[0086] The present invention has been described in detail above with reference to the embodiments, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A liquid injection process for improving the cycle life of soft-pack lithium-ion batteries, characterized in that, The following steps are included: S1. First electrolyte injection: Inject 50%-90% of the total electrolyte volume into the battery cell; S2. Pretreatment: Pressurize the inside of the battery for 5-10 seconds, repeat 4-10 times, then remove the vacuum and seal the edges. Then, place the battery in an insulated box for high-temperature static immersion for 30-120 minutes. S3. Pre-charge formation: The state of charge (SOC) of the formed charge is 20%-90%; S4. Second electrolyte injection: Inject half of the remaining electrolyte volume, pressurize for 5-10 seconds, repeat 4-10 times, and then vacuum and seal the battery. S5. High-temperature static wetting: Place the battery in an insulated box and immerse it for 30-90 minutes; S6. Formation: The state of charge (SOC) of the formation charge is 3-20%; S7. Temperature and Pressure Settling: Place the battery in a temperature and pressure settling box and let it stand for 1-4 hours; S8. Third injection: Fill the remaining volume of the total injection volume, then vacuum and seal the edges; The electrolyte is 1.0-1.1M LiPF6, with a solvent ratio of EC / DEC / EMC = 1:1:1 and an additive of VC. The positive electrode material of the lithium-ion battery is lithium iron phosphate, and the negative electrode adopts the traditional graphite negative electrode. The pressure applied in S2 and S4 is 0.3-1 MPa; The temperature inside the insulated box is 25℃-65℃; The formation time is 1-5 hours, and the formation current is 0.002-5C; The temperature inside the insulation and pressure-holding box is 25-65°C, and the pressure is 0.1-0.8 MPa.

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