Formation method of high-capacity lithium ion battery

Abstract

The invention discloses a formation method of a high-capacity lithium ion battery, which comprises the following steps of: 1) pretreating the battery, and infiltrating a battery pole piece in electrolyte; 2) charging the battery for the first time so as to initially activate the battery; 3) charging the battery for the second time so as to further activate the battery; and (4) charging the battery for the third time to complete the battery formation process, so that the battery pole piece can be fully infiltrated in a short time by changing the specific formation process, the infiltrating efficiency of the pole piece is enhanced, and the industrial production capacity of the lithium ion battery is also improved. In addition, the new formation charging mode enables the SEI formed on the surface of the electrode to be more uniform and compact, and the performance of the obtained battery is more excellent.

Description

Technical Field

[0001] The invention belongs to the technical field of power batteries, and in particular relates to a formation method for a large-capacity lithium-ion battery. Background Art

[0002] In the process of implementing the present invention, the inventors found that the prior art has at least the following problems:

[0003] Lithium-ion batteries are a new type of high-energy battery developed in the 20th century. They have been widely used in various fields of social life due to their advantages such as high energy, high voltage, wide operating temperature range and long life. At present, lithium-ion batteries are developing in the direction of large capacity, long cycle and high energy density in the field of industrial and commercial energy storage. At the same time, this also puts higher requirements on the manufacturing process.

[0004] In the manufacturing process of lithium-ion batteries, formation is an extremely important process. It forms a solid electrolyte interface (SEI) film on the surface of the battery's negative electrode. The quality of the film formation plays a vital role in the battery's capacity, charge and discharge performance, cycle life, storage performance, etc.

[0005] The existing technology requires high-temperature standing to allow the electrode to be fully infiltrated with electrolyte after the first injection of lithium-ion batteries to complete the formation process, and then several steps of constant current charging to form an SEI film on the surface of the negative electrode. Large-capacity batteries have higher design capacity, more electrode layers, wider electrode membrane surfaces, and tighter internal electrode stacking. It is difficult for the existing formation process to fully infiltrate the battery electrode by capillary action alone, and the cycle required to complete the production of large-capacity batteries is longer. Black spots and even lithium precipitation are prone to occur on the negative electrode interface. In addition, the formed SEI film is not dense and uniform enough to meet the design performance requirements of large-capacity lithium-ion batteries.

[0006] CN109599595A-A formation method for a lithium-ion battery with a long storage life, discloses a formation method for a lithium-ion battery with a long storage life, wherein the positive electrode active material in the lithium-ion battery is mainly composed of LiNi0.7Mn0.2Ni0.1O2, and the electrolyte of the lithium-ion battery includes additives composed of vinylene carbonate VC and fluoroethylene carbonate FEC, wherein VC accounts for 0.5-1% of the total volume of the electrolyte, and the above-mentioned technical problems cannot be solved. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a formation method for a large-capacity lithium-ion battery. By changing the specific formation process, the battery pole piece can be fully wetted in a short time, thereby enhancing the efficiency of the pole piece wetting and also improving the production capacity of the industrial production of lithium-ion batteries.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a formation method of a large-capacity lithium-ion battery, comprising the following steps:

[0009] 1) Battery pretreatment to immerse the battery pole pieces in the electrolyte;

[0010] 2) Charging the battery for the first time to initially activate the battery;

[0011] 3) charging the battery a second time to further activate the battery;

[0012] 4) Charge the battery for the third time to complete the battery formation process.

[0013] In the above step 1), after the battery is injected once, the battery pole piece is immersed in the electrolyte at a temperature of 35-55° C. to achieve full infiltration of the battery pole piece and the electrolyte.

[0014] In the above step 1), the battery is subjected to positive and negative pressures of 30 to 50 Pa and -40 to -60 KPa in a periodic alternating manner to allow the battery pole piece to be infiltrated with the electrolyte, thereby achieving full infiltration of the battery pole piece with the electrolyte.

[0015] In the above step 1), the battery pole piece and the electrolyte are soaked for 3-6 hours to achieve full soaking of the battery pole piece and the electrolyte.

[0016] In the above step 2), for the first charge, the battery is cooled to 20-30°C and charged to 3.0V at a constant current of 0.02C-0.06C. The initial activation of the battery is completed, and the SEI film is more uniform and dense, which is conducive to the orderly growth of the subsequent SEI film.

[0017] In the above step 2), the first charge is carried out under negative pressure of -50 to -70 KPa, which is conducive to the discharge of gas generated during the battery formation process.

[0018] In the above step 3), for the second charge, the battery is heated to 35-55°C and charged to 5% SOC at a constant current of 0.08C-0.12C, which is conducive to the further stable growth of the SEI film.

[0019] In the above step 3), the second charging is carried out under negative pressure of -70 to -90 KPa, which is conducive to the discharge of gas generated during the battery formation process.

[0020] In the above step 4), the third charge is performed at a temperature of 35 to 55° C. and a constant current of 0.16 to 0.22 C to 30% SOC. This is conducive to quickly completing the battery formation process and improving production capacity.

[0021] In the above step 4), the third charge is carried out under negative pressure of -70 to -90 KPa, which is conducive to the discharge of gas generated during the battery formation process.

[0022] One of the above technical solutions has the following advantages or beneficial effects: by changing the specific formation process, the battery pole piece can be fully wetted in a short time, thereby enhancing the efficiency of pole piece wetting and improving the production capacity of industrial production of lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is an experimental comparison diagram of the formation method of a large-capacity lithium-ion battery provided in an embodiment of the present invention; DETAILED DESCRIPTION

[0024] 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.

[0025] Embodiment 1

[0026] A formation method for a large-capacity lithium-ion battery comprises the following steps:

[0027] (1) Place the battery that has completed the first injection in a pressure forming device, set the temperature to 45°C, set the positive pressure of the forming press to 40Pa, and the negative pressure to -50Kpa, and apply positive pressure for 10s, negative pressure for 10s, and positive and negative pressure alternately for 3h to achieve full infiltration of the battery electrode and the electrolyte.

[0028] (2) The battery after step (1) is cooled to 25°C and charged to 3.0V at a constant current of 0.05C under a negative pressure of -60KPa. The initial activation of the battery is completed under low temperature and low current conditions, and the SEI film is more uniform and dense, which is conducive to the orderly growth of the subsequent SEI film.

[0029] (3) The temperature of the battery environment was raised to 45°C, and the battery was charged to 5% SOC at a constant current of 0.1C under a negative pressure of -80KPa to complete further activation of the battery.

[0030] (4) The battery is charged to 30% SOC at a constant current of 0.18C at 45°C and a negative pressure of -80KPa, and the entire formation process is completed quickly.

[0031] See also Figure 1By changing the specific formation process, the battery pole piece can be fully wetted in a short time, which enhances the efficiency of pole piece wetting and improves the production capacity of industrialized production of lithium-ion batteries. In addition, the new formation charging method makes the SEI formed on the electrode surface more uniform and dense, and the obtained battery performance is better.

[0032] Embodiment 2

[0033] A formation method for a large-capacity lithium-ion battery comprises the following steps:

[0034] 1) Battery pretreatment to immerse the battery pole pieces in the electrolyte;

[0035] 2) Charging the battery for the first time to initially activate the battery;

[0036] 3) charging the battery a second time to further activate the battery;

[0037] 4) Charge the battery for the third time to complete the battery formation process.

[0038] In the above step 1), after the battery is injected once, the battery pole pieces are immersed in the electrolyte at a temperature of 35 to 55°C.

[0039] In the above step 1), the battery is subjected to positive and negative pressures of 30 to 50 Pa and -40 to -60 KPa in a periodic alternating manner, so that the battery electrodes are infiltrated with the electrolyte.

[0040] In the above step 1), the battery electrode is immersed in the electrolyte for 3-6 hours.

[0041] In the above step 2), for the first charge, the battery is cooled to 20-30°C and charged to 3.0V at a constant current of 0.02C-0.06C.

[0042] In the above step 2), the first charging is carried out under a negative pressure condition of -50 to -70 KPa.

[0043] In the above step 3), for the second charging, the battery is heated to 35-55°C and charged to 5% SOC at a constant current of 0.08C-0.12C.

[0044] In the above step 3), the second charging is carried out under negative pressure of -70 to -90 KPa.

[0045] In the above step 4), the third charge is performed at a temperature of 35 to 55° C. and a constant current of 0.16 to 0.22 C to 30% SOC.

[0046] In the above step 4), the third charging is carried out under negative pressure of -70 to -90 KPa.

[0047] After adopting the above scheme, by changing the specific process of formation, the battery pole piece can be fully wetted in a short time, which enhances the efficiency of pole piece wetting and also improves the production capacity of industrial production of lithium-ion batteries.

[0048] Comparative Example 1

[0049] (1) Place the battery after the first injection in a pressure forming device, set the temperature to 45°C, and let it stand for 48 hours to complete the battery impregnation.

[0050] (2) The battery environment is placed at a temperature of 45°C and a negative pressure of -80KPa, and the battery is charged to 5% SOC at a constant current of 0.1C to complete the initial activation of the battery.

[0051] (3) The battery environment is placed at a temperature of 45°C and a negative pressure of -80KPa, and the battery is charged to 30% SOC at a constant current of 0.18C to quickly complete the entire formation process.

[0052] See also Figure 1 By changing the specific formation process, the battery pole piece can be fully wetted in a short time, which enhances the efficiency of pole piece wetting and improves the production capacity of industrialized production of lithium-ion batteries. In addition, the new formation charging method makes the SEI formed on the electrode surface more uniform and dense, and the obtained battery performance is better.

[0053] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0054] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0055] 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 formation method for a large-capacity lithium-ion battery, characterized in that: The steps include: 1) Battery pretreatment to immerse the battery pole pieces in the electrolyte; 2) Charging the battery for the first time to initially activate the battery; 3) charging the battery a second time to further activate the battery; 4) Charge the battery for the third time to complete the battery formation process.

2. The formation method of a large-capacity lithium-ion battery according to claim 1, characterized in that: In the above step 1), after the battery is injected once, the battery pole pieces are immersed in the electrolyte at a temperature of 35 to 55°C.

3. The formation method of a large-capacity lithium-ion battery as claimed in claim 2, characterized in that: In the above step 1), the battery is subjected to positive and negative pressures of 30 to 50 Pa and -40 to -60 KPa in a periodic alternating manner, so that the battery electrodes are infiltrated with the electrolyte.

4. The formation method of a large-capacity lithium-ion battery as claimed in claim 3, characterized in that: In the above step 1), the battery electrode is immersed in the electrolyte for 3-6 hours.

5. The formation method of a large-capacity lithium-ion battery as claimed in claim 4, characterized in that: In the above step 2), for the first charge, the battery is cooled to 20-30°C and charged to 3.0V at a constant current of 0.02C-0.06C.

6. The formation method of a large-capacity lithium-ion battery according to claim 5, characterized in that: In the above step 2), the first charging is carried out under a negative pressure condition of -50 to -70 KPa.

7. The formation method of a large-capacity lithium-ion battery according to claim 6, characterized in that: In the above step 3), for the second charging, the battery is heated to 35-55°C and charged to 5% SOC at a constant current of 0.08C-0.12C.

8. The formation method of a large-capacity lithium-ion battery according to claim 7, characterized in that: In the above step 3), the second charging is carried out under negative pressure of -70 to -90 KPa.

9. The formation method of a large-capacity lithium-ion battery according to claim 8, characterized in that: In the above step 4), the third charge is performed at a temperature of 35 to 55° C. and a constant current of 0.16 to 0.22 C to 30% SOC.

10. The formation method of a large-capacity lithium-ion battery according to claim 9, characterized in that: In the above step 4), the third charging is carried out under negative pressure of -70 to -90 KPa.

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