Battery formation device and battery formation method

Abstract

The application relates to the technical field of battery preparation, in particular to a battery formation device and a battery formation method. The formation method comprises a constant current stage, in the constant current stage, the constant current stage is divided into at least two stages according to the speed of gas generation, the at least two stages comprise a first stage and a second stage, the second stage occurs after the first stage, the second stage is a high-speed gas generation stage, the speed of gas generation in the first stage is less than that in the second stage, and the second stage and / or stages after the second stage are used for supplementing liquid to the battery. According to the battery formation method, the constant current stage is divided into at least two stages, and the battery interior is supplemented with liquid, so that the electrolyte can flow into the battery more easily, the supplementing efficiency can be improved, the electrolyte can be fully soaked during formation, and the SEI formation yield during battery formation can be improved.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, and in particular to a battery formation apparatus and a battery formation method. Background Technology

[0002] Lithium-ion batteries are widely used in electric vehicles, electronics, energy storage and other fields due to their advantages such as high energy density, long cycle life, wide operating temperature range, low self-discharge rate, stable operating voltage platform, no memory effect and clean and pollution-free operation. They have broad application prospects and market demand.

[0003] A lithium-ion battery is a complex system that includes a positive electrode, a negative electrode, a separator, an electrolyte, a current collector, a binder, and a conductive agent. The reactions involved include electrochemical reactions at the positive and negative electrodes, lithium-ion and electron conduction, and heat dissipation. The manufacturing process for lithium batteries is lengthy, involving more than 50 steps.

[0004] After lithium-ion batteries are packaged, they enter the formation process (one of the most crucial processes affecting battery performance). Formation refers to the electrochemical process in which a specific current is applied to the positive and negative electrode active materials of the lithium-ion battery, activating them and ultimately giving the battery the ability to discharge. Factors affecting formation include formation current, state of charge (SOC), aging time, and temperature; the battery material system and production capacity requirements must also be considered. Formation is not simply a matter of charging and discharging; it measures the impact on battery performance. Extensive research and validation are required, along with matching the process to the battery itself.

[0005] In the manufacturing process of lithium-ion batteries, formation is a crucial step that determines the performance of the battery. After electrolyte injection and high-temperature immersion, formation occurs during the formation process, resulting in a reduction of the electrolyte level inside the battery. When the total amount of electrolyte is insufficient, it directly affects the battery's electrical performance and cycle performance. Summary of the Invention

[0006] This invention provides a battery formation apparatus and a battery formation method to solve the defects in the prior art caused by the reduction of electrolyte inside the battery due to chemical reactions and other reasons. It reduces the amount of electrolyte loss, ensures sufficient electrolyte wetting during formation, improves the SEI formation yield during battery formation, and reduces the time required for standing at room temperature after formation.

[0007] The present invention provides a battery formation method, comprising: the formation method including a constant current stage, wherein the constant current stage is divided into at least two stages according to the gas generation rate, the at least two stages including a first stage and a second stage, the second stage occurring after the first stage, the second stage being a high-speed gas generation stage, wherein the gas generation rate in the first stage is less than the gas generation rate in the second stage, and the battery is replenished with electrolyte in the second stage and / or in the stages following the second stage.

[0008] According to the battery formation method provided by the present invention, the first stage uses a vacuum method to maintain the battery cavity in a low negative pressure state.

[0009] The second stage uses a vacuum method to maintain a high negative pressure state inside the battery cavity, and the absolute value of the negative pressure in the first stage is less than the absolute value of the negative pressure in the second stage.

[0010] According to the battery formation method provided by the present invention, the constant current stage further includes a third stage based on the gas generation rate. The third stage occurs after the second stage. The gas generation rate in the second stage is greater than the gas generation rate in the third stage. The third stage uses a vacuum method to maintain the battery cavity in a low negative pressure state. The absolute value of the negative pressure in the third stage is less than the absolute value of the negative pressure in the second stage.

[0011] According to the battery formation method provided by the present invention, the absolute value of the negative pressure in the first stage ranges from 35 to 45 MPa, the absolute value of the negative pressure in the second stage ranges from 75 to 85 MPa, and the absolute value of the negative pressure in the third stage ranges from 35 to 45 MPa.

[0012] The battery formation method provided by the present invention further includes a constant pressure stage, wherein the constant pressure stage is performed after the constant current stage and during the constant pressure stage, liquid replenishment is performed.

[0013] According to the battery formation method provided by the present invention, when replenishing the battery with electrolyte, the amount of electrolyte replenished is 5%-10% of the total amount of electrolyte in the battery.

[0014] According to the battery formation method provided by the present invention, the battery formation apparatus is used for battery formation and includes an injection pump, a liquid circuit switching valve and a plurality of liquid replenishment branches arranged in parallel. The liquid circuit switching valve is adapted to control the on / off state of each of the liquid replenishment branches, and the injection pump is used to pump electrolyte into the corresponding liquid replenishment branch.

[0015] According to the battery formation method provided by the present invention, when replenishing the battery electrolyte, the amount of electrolyte delivered to each of the replenishment branches is the same.

[0016] According to the battery formation method provided by the present invention, when the number of replenishment operations is multiple, the amount of replenishment is the same each time.

[0017] According to the battery formation method provided by the present invention, during the battery formation process, the total amount of electrolyte replenished shall not exceed 15% of the total amount of electrolyte in the battery.

[0018] The present invention also provides a battery formation apparatus, the battery formation apparatus being adapted to apply the battery formation method described above, the battery formation apparatus comprising:

[0019] The electrolyte injection device has an injection chamber, and the electrolyte in the injection chamber is suitable for flowing into the battery.

[0020] A fluid replenishment branch is connected to the injection chamber and is used to replenish fluid into the injection chamber;

[0021] The electrolyte injection pump is used to pump electrolyte into the corresponding replenishment branch.

[0022] The battery formation apparatus provided by the present invention further includes: a liquid circuit switching valve, the liquid circuit switching valve being adapted to control the on / off state of the replenishment branch.

[0023] The battery formation apparatus provided by the present invention further includes: a negative pressure pipeline, the negative pressure pipeline being connected to the injection chamber for evacuating the injection chamber.

[0024] The battery formation apparatus provided by the present invention further includes: a negative pressure suction nozzle, wherein the liquid injection device is connected to the battery through the negative pressure suction nozzle.

[0025] According to the battery formation apparatus provided by the present invention, there are multiple replenishment branches, and the multiple replenishment branches are arranged in parallel.

[0026] According to the battery formation method of the present invention, the constant current stage is divided into at least two stages, and electrolyte is replenished inside the battery. The electrolyte flows into the battery more easily, thereby improving the replenishment efficiency. This can improve the electrolyte wetting sufficiency during formation and increase the SEI formation yield during battery formation. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the battery formation apparatus provided by the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the liquid injection device provided by the present invention in conjunction with the battery;

[0030] Figure 3 This is a schematic diagram of the liquid injection device provided by the present invention;

[0031] Figure label:

[0032] 100: Battery formation device; 200: Battery;

[0033] 110: Liquid injection device;

[0034] 120: Injection pump; 130: Fluid circuit switching valve; 140: Replenishment branch;

[0035] 150: Negative pressure pipeline; 160: Negative pressure suction nozzle. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] The following is combined Figures 1 to 3 This invention describes a battery formation method and a battery formation apparatus 100 according to embodiments of the present invention. It should be noted that formation is achieved by activating the battery cell through a first charge, during which an effective passivation film (SEI film) is generated on the negative electrode surface to "initialize" the battery 200. During the production of the battery 200, the battery formation method can be performed within the battery formation apparatus 100; during the formation reaction, gas is generated inside the battery 200. The formation reaction includes a constant current stage, which is further divided into at least two stages based on the gas generation rate. These at least two stages include a first stage and a second stage, with the second stage occurring after the first stage. The second stage is a high-speed gas generation stage, where the gas generation rate in the first stage is less than that in the second stage. The battery is replenished with electrolyte during the second stage and / or subsequent stages.

[0038] It's important to note that during the constant-current phase of the battery formation reaction, the relationship between gas production and time generally follows a sinusoidal curve. Based on this relationship, the formation reaction process can be divided into multiple stages. For example, the formation reaction can be divided into a first stage and a second stage. The first stage is a low-pressure stage, where the gas production rate can be V1; the second stage is a high-pressure stage, where the gas production rate can be V2, where V2 ≥ V1.

[0039] According to the battery formation method of the present invention, the constant current stage is divided into at least two stages, and electrolyte is replenished inside the battery. The electrolyte flows into the battery more easily, thereby improving the replenishment efficiency. This can improve the electrolyte wetting sufficiency during formation and increase the SEI formation yield during battery formation.

[0040] According to some embodiments of the present invention, in the first stage, a vacuum is used to maintain the battery cavity at a low negative pressure, and in the second stage, a vacuum is used to maintain the battery cavity at a high negative pressure. The absolute value of the negative pressure in the first stage is less than that in the second stage. Therefore, under different negative pressure conditions, gas overflow can be accelerated, thereby shortening the formation time.

[0041] According to some embodiments of the present invention, the constant current stage further includes a third stage, which occurs after the second stage. The gas generation rate in the second stage is greater than the gas generation rate in the third stage. The third stage uses a vacuum method to maintain a low negative pressure state inside the battery cavity, and the absolute value of the negative pressure in the third stage is less than the absolute value of the negative pressure in the second stage. This allows the electrolyte to flow into the battery quickly, thereby improving the smoothness of electrolyte replenishment.

[0042] According to some embodiments of the present invention, the absolute value of the negative pressure in the first stage ranges from 35 to 45 MPa, the absolute value of the negative pressure in the second stage ranges from 75 to 85 MPa, and the absolute value of the negative pressure in the third stage ranges from 35 to 45 MPa.

[0043] In the formation reaction, the battery formation method also includes a constant-pressure stage, which follows the constant-current stage and involves electrolyte replenishment. This allows for further electrolyte replenishment inside the battery, making it easier for the electrolyte to flow into the battery and improving replenishment efficiency. This, in turn, enhances electrolyte wetting during formation and increases the SEI formation yield.

[0044] According to some embodiments of the present invention, when replenishing the battery electrolyte, the replenishment amount is 5%-10% of the total electrolyte in the battery. It should be noted that in the second stage of the formation reaction, during the first replenishment step, the replenishment amount is 5%-10% of the total electrolyte in the battery 200. This ensures sufficient electrolyte in the battery 200, improving electrolyte wetting during formation. According to some embodiments of the present invention, in the third stage, the replenishment amount can be 5%-10% of the total electrolyte in the battery. According to some embodiments of the present invention, during the constant voltage stage, the replenishment amount is 5%-10% of the total electrolyte in the battery 200, thereby ensuring sufficient electrolyte in the battery.

[0045] like Figures 1-3 As shown, the battery formation apparatus 100 according to an embodiment of the present invention includes: a liquid injection device 110, a liquid replenishment branch 140, a liquid injection pump 120, and a liquid circuit switching valve 130.

[0046] Specifically, the electrolyte injection device 110 has an injection chamber that temporarily stores the electrolyte, facilitating its flow into the battery 200. It should be noted that the electrolyte can first flow into the injection chamber and then into the battery 200, ensuring a smooth flow of electrolyte into the battery 200. The type of battery 200 is not specifically limited; for example, in some examples, the battery 200 can be a prismatic battery; in other examples, it can be a cylindrical battery.

[0047] The replenishment branch 140 is connected to the injection chamber and is used to replenish electrolyte into the injection chamber. The injection pump 120 is used to pump electrolyte into the corresponding replenishment branch 140. The liquid circuit switching valve 130 is adapted to control the on / off state of the replenishment branch 140. Here, the injection pump 120 can serve as a power source to drive the flow of electrolyte.

[0048] It should be noted that the liquid circuit switching valve 130 controls the opening and closing of the replenishment branch 140 through its opening and closing actions. For example, when it is necessary to replenish electrolyte into the replenishment branch 140, the liquid circuit switching valve 130 opens, at which time the replenishment branch 140 is connected to the injection chamber, and the liquid in the replenishment branch 140 can flow into the injection chamber; when it is not necessary to replenish electrolyte into the replenishment branch 140, the liquid circuit switching valve 130 closes, at which time the replenishment branch 140 is blocked from the injection chamber, and the liquid in the replenishment branch 140 cannot flow into the injection chamber.

[0049] When there are multiple replenishment branches 140, and these branches are connected in parallel, the liquid circuit switching valve 130 can control the on / off state of the corresponding replenishment branch 140. This allows for directional control of the on / off state of the corresponding replenishment branch 140, thereby enabling replenishment of a specific battery 200. Furthermore, by controlling the operating time of the liquid circuit switching valve 130, the duration of connection of the replenishment branch 140 can be controlled, thereby controlling the amount of liquid replenished.

[0050] Therefore, by setting up the electrolyte replenishment branch 140, electrolyte can be replenished inside the battery 200, which reduces electrolyte loss, ensures sufficient electrolyte wetting during formation, and thus improves the SEI film formation yield during battery 200 formation. Furthermore, sufficient electrolyte in the battery 200 also reduces the post-formation room temperature settling time. Moreover, by setting up the liquid circuit switching valve 130, the on / off state of the corresponding electrolyte replenishment branch 140 can be controlled, and the replenishment amount can be controlled by controlling the connection time of the electrolyte replenishment branch 140, thereby facilitating the control of the replenishment amount.

[0051] According to some embodiments of the present invention, the amount of electrolyte delivered to each replenishment branch can be the same in each replenishment step. This facilitates control of the replenishment amount, and also facilitates control of the replenishment amount for each battery. Of course, in some embodiments, the replenishment amount is the same at each stage. Therefore, the battery 200 can have sufficient electrolyte, which can improve the adequacy of electrolyte wetting during formation.

[0052] Of course, in order to improve the replenishment efficiency, according to some embodiments of the present invention, the total amount of replenishment in each stage shall not exceed 15% of the total electrolyte in the battery. For example, the total amount of replenishment in the first replenishment and the total amount of replenishment in the second replenishment shall not exceed 15% of the total electrolyte in the battery 200.

[0053] According to some embodiments of the present invention, see Figure 2 As shown, the battery formation apparatus 100 may further include a negative pressure pipeline 150, which is connected to the liquid injection chamber and used to evacuate the liquid injection chamber. It should be noted that the negative pressure pipeline 150 can keep the liquid injection chamber under negative pressure. In this negative pressure environment, the gas generated inside the battery 200 can escape more easily, thereby shortening not only the formation time of the battery 200 but also the post-formation room temperature settling time. It should be noted that during the formation reaction of the battery 200, the pressure inside the liquid injection chamber is P1 in the low negative pressure stage and P2 in the high negative pressure stage, where P2 ≥ P1. This allows the gas generated during the formation reaction to escape rapidly.

[0054] According to some embodiments of the present invention, see Figure 2As shown, the battery formation apparatus 100 also includes a negative pressure suction nozzle 160, through which the liquid injection device 110 is connected to the battery 200. This not only facilitates the connection between the liquid injection device 110 and the battery 200, but also facilitates the formation of a negative pressure ring inside the battery 200 and the liquid injection device 110, thereby accelerating gas escape.

[0055] According to the battery formation method of the present invention, the formation reaction is divided into at least two stages based on the gas generation rate in the battery formation reaction, and liquid replenishment is performed in each stage.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery formation method, characterized in that, The battery formation method includes a constant current stage and a constant pressure stage. Liquid replenishment is performed in both the constant current stage and the constant pressure stage. Within the constant current stage, the stage is divided into a first stage, a second stage, and a third stage based on the gas generation rate. The second stage occurs after the first stage, and the third stage occurs after the second stage. The second stage is a high-speed gas generation stage. The first stage uses vacuuming to maintain a low negative pressure state inside the battery cavity. The second stage uses vacuuming to maintain a high negative pressure state inside the battery cavity. The third stage uses vacuuming to maintain a low negative pressure state inside the battery cavity. The absolute value of the negative pressure in the first stage is less than that in the second stage, and the absolute value of the negative pressure in the third stage is less than that in the second stage. The gas generation rate in the first stage and the third stage is less than that in the second stage. Liquid replenishment is performed on the battery during the second stage and the third stage. The constant pressure stage is performed after the constant flow stage, and during the constant pressure stage, liquid replenishment is carried out; When replenishing the battery, the amount of electrolyte added each time is 5%-10% of the total electrolyte in the battery, and the total amount of electrolyte added in each stage shall not exceed 15% of the total electrolyte in the battery. The absolute value of the negative pressure in the first stage ranges from 35 to 45 MPa, the absolute value of the negative pressure in the second stage ranges from 75 to 85 MPa, and the absolute value of the negative pressure in the third stage ranges from 35 to 45 MPa.

2. The battery formation method according to claim 1, characterized in that, A battery formation device is used for battery formation and includes an injection pump, a liquid circuit switching valve, and multiple replenishment branches arranged in parallel. The liquid circuit switching valve is adapted to control the on / off state of each replenishment branch, and the injection pump is used to pump electrolyte into the corresponding replenishment branch.

3. The battery formation method according to claim 2, characterized in that, When replenishing the battery electrolyte, the same amount of electrolyte is delivered to each of the replenishment branches.

4. The battery formation method according to claim 1, characterized in that, When fluid replacement is performed multiple times, the amount of fluid replaced each time is the same.

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