Battery cell formation liquid loss measuring mechanism

Abstract

The present application provides a kind of electric core formation liquid loss measuring mechanism, wherein, including with the electric core gas of being carried out gas flow connection collector, in the collector, can be dissolved in the auxiliary solution of electrolyte from the gas of electric core discharge.

Description

Technical Field

[0001] This invention relates to the field of battery cell formation technology, and more specifically, to a battery cell formation liquid loss measurement mechanism. Background Technology

[0002] In the manufacturing process of lithium-ion power cells, there is a step called "formation," which aims to react the negative electrode of the cell with the electrolyte to form an electronically insulating and ionically conductive solid-phase interface electrolyte film (SEI film) on the surface of the negative electrode, thus enabling the lithium-ion cell to function properly. During the formation process, the reaction between the electrolyte and the negative electrode of the cell produces a significant amount of gas. If these gases remain in the battery, they can affect the cell's performance, so they need to be removed.

[0003] Currently, the commonly used formation method for lithium-ion power batteries is negative pressure formation, which involves applying a certain negative pressure to the battery during the formation process to extract the generated gas. However, under negative pressure conditions, the electrolyte in the cell is usually discharged with the gas, resulting in electrolyte loss. Typically, the lost electrolyte can be calculated by weighing the cell after formation and the cell before formation and taking the difference. However, for certain special cell structures (such as internal series-coated cells, where different cavities need to be isolated from each other and each needs to be formed individually), weighing cannot determine the amount of electrolyte loss in each cavity. Summary of the Invention

[0004] One aspect of the technical problem to be solved by the present invention is how to quantitatively measure the electrolyte loss during the formation of a battery cell without weighing the cell.

[0005] Furthermore, other aspects of the present invention are also intended to solve or alleviate other technical problems existing in the prior art.

[0006] This invention provides a cell formation liquid loss measurement mechanism. Specifically, according to one aspect of the invention, it provides: A cell formation liquid loss measuring mechanism includes a collector circumferentially connected to the cell gas undergoing formation, wherein the collector contains an auxiliary solution capable of dissolving the electrolyte in the gas discharged from the cell.

[0007] Optionally, according to one embodiment of the invention, the collector has a collection chamber for containing the auxiliary solution and a cooling chamber for containing coolant, the cooling chamber being arranged around the collection chamber, the collection chamber having an air inlet and an air outlet, and the cooling chamber having a coolant inlet and a coolant outlet.

[0008] Optionally, according to one embodiment of the present invention, the cell formation liquid loss measuring mechanism further includes a negative pressure generating device, the negative pressure generating device being connected to the outlet of the collector via a first pipeline, the inlet of the collector being connected to the cell via a second pipeline, and the negative pressure generating device drawing gas from the cell into the collector via the first pipeline, the collection chamber, and the second pipeline.

[0009] Optionally, according to one embodiment of the present invention, the collection chamber is configured as a cylindrical chamber with a volume greater than or equal to 50 ml, wherein the ratio of the height to the diameter of the bottom surface of the cylindrical chamber is greater than or equal to 3.

[0010] Optionally, according to one embodiment of the present invention, the second conduit extends from the air inlet of the collecting chamber into the collector until the bottom surface of the collecting chamber, and a first region of the bottom surface directly opposite the outlet cross-section of the second conduit is configured as a plane parallel to the horizontal plane of the auxiliary solution, and the other regions of the bottom surface excluding the first region are configured as inclined surfaces extending obliquely upward from the first region.

[0011] Optionally, according to one embodiment of the present invention, a liquid level collector is arranged in the collection chamber for measuring the volume of the auxiliary solution.

[0012] Optionally, according to one embodiment of the present invention, the cell formation liquid loss measuring mechanism further includes a cooling device, which is connected to the coolant inlet and coolant outlet of the cooling chamber respectively and supplies coolant to the cooling chamber.

[0013] Optionally, according to one embodiment of the present invention, the cell formation liquid loss measuring mechanism further includes the auxiliary solution storage device, wherein the end of the second pipeline away from the collector branches into a first branch pipe and a second branch pipe, the first branch pipe being connected to the cell and the second branch pipe being connected to the auxiliary solution storage device.

[0014] Optionally, according to one embodiment of the present invention, valves are respectively constructed on the first branch pipe and the second branch pipe for opening and cutting off the flow of gas and liquid in the first branch pipe and the second branch pipe.

[0015] Optionally, according to one embodiment of the present invention, the auxiliary solution is linear carbonic acid or alcohol.

[0016] Optionally, according to one embodiment of the present invention, the auxiliary solution is dimethyl carbonate, ethyl methyl carbonate, ethanol, or ethylene glycol.

[0017] The advantages of this invention include: by adding a collector containing an organic solvent miscible with the electrolyte as an auxiliary solution, this invention can collect the electrolyte extracted under negative pressure during formation and the electrolyte vaporized by heating. The electrolyte loss during formation can then be determined by the difference in liquid volume before and after formation. The collector also has a cooling structure, which liquefies the vaporized electrolyte and allows it to be completely absorbed by the organic solvent, thereby improving the accuracy of electrolyte loss measurement. Furthermore, the cell formation liquid loss measurement mechanism of this invention allows for the replacement of the auxiliary solution through different air channels. In addition, the cell formation liquid loss measurement mechanism of this invention can reduce the weighing process before replenishing the electrolyte in the cells, thus improving productivity. Attached Figure Description

[0018] Referring to the accompanying drawings, the above and other features of the present invention will become apparent, wherein, Figure 1 This illustrates a cell formation liquid loss measurement mechanism according to an embodiment of the present invention; Figure 2 A schematic diagram of the bottom surface of the collection chamber of the collector of a cell formation liquid loss measuring mechanism according to an embodiment of the present invention is shown. Detailed Implementation

[0019] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0020] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive. Furthermore, the terms "first," "second," "third," and similar expressions are used for descriptive and distinguishing purposes only and should not be construed as indicating or implying the relative importance of the corresponding components.

[0021] refer to Figure 1 This illustrates a cell formation electrolyte loss measurement mechanism according to an embodiment of the present invention. This mechanism is used to accurately and quantitatively measure electrolyte loss in a cell 200 due to gas emission during the formation process. The mechanism includes a collector 1, a negative pressure generating device 2, and a cooling device (in... Figure 1(Not shown in the image) and auxiliary solution storage device 3. The collector 1 contains an auxiliary solution (in the image) capable of dissolving gaseous or liquid electrolyte. Figure 1 (Not specifically shown), used to dissolve the gaseous or liquid electrolyte contained in the gas discharged from the cell 200. This auxiliary solution is an organic solvent that is miscible with the electrolyte, such as linear carbonic acid or alcohol liquid. Specifically, for example, the auxiliary solution may be dimethyl carbonate (DMC) or ethyl methyl carbonate (EMC), or ethanol or ethylene glycol, etc.

[0022] exist Figure 1 In one embodiment, the entire collector 1 is constructed in a cylindrical shape. The collector 1 has a collection chamber 11 for containing an auxiliary solution and a cooling chamber 12 for containing a coolant. The collection chamber 11 is constructed in a cylindrical shape, while the cooling chamber 12 is arranged around the collection chamber 11, for example, configured to... Figure 1 The hollow cylindrical shape of the chamber maximizes the heat exchange area between the coolant and the auxiliary solution, ensuring better cooling of the auxiliary solution and maximizing the electrolyte's dissolution effect. For improved collection, the cylindrical collection chamber 11 has a volume of at least 50 ml, and the ratio of its height to its base diameter is at least 3. This allows the chamber to hold a large amount of auxiliary solution, and the higher the height of the auxiliary solution within the chamber, the longer the gas input from the battery cell 200 remains in the auxiliary solution, further enhancing the dissolution effect. A liquid level collector 5, for measuring the volume of the auxiliary solution, is installed in the collection chamber 11, for example, on its inner wall. The cooling chamber 12 has a coolant inlet 121 and a coolant outlet 122, which are connected to the cooling device via pipes to circulate the coolant. In other words, the cooling device supplies coolant (e.g., water) to the coolant inlet 121 through a pipeline. When the coolant absorbs heat and its temperature rises, it flows back to the cooling device from the coolant outlet 122 through the pipeline for cooling.

[0023] The collection chamber 11 has an air inlet 111 and an air outlet 112. The air outlet 112 of the collection chamber 11 is connected to the negative pressure generating device 2 via a first pipe 6, and the air inlet 111 of the collection chamber 11 is connected to the battery cell 200 via a second pipe 7. In one embodiment of the present invention, the air inlet 111 is connected to a formation suction nozzle 300 mounted on the battery cell 200 via the second pipe 7. The formation suction nozzle 300 is connected to the liquid injection nozzle of the battery cell 200, and the liquid injection nozzle is not on the battery cell 200. Figure 1As shown in the figure. The negative pressure generating device 2 can be, for example, a vacuum pump. The negative pressure generating device 2 draws the gas in the battery cell 200 into the collector 11 via the first pipe 6, the collection chamber 11 and the second pipe 7, and then draws it into the negative pressure generating device 2 and discharges it through the negative pressure generating device 2.

[0024] The second conduit 7 branches off from the collector 1 into a first branch 71 and a second branch 72. The first branch 71 connects to the battery cell 200 undergoing formation, or to the formation nozzle 300 mounted on the battery cell 200. The second branch 72 connects to the auxiliary solution storage device 3. The auxiliary solution storage device 3 is used to supply auxiliary solution to the collector 1 and to recover auxiliary solution from the collector 1. A first valve 710 and a second valve 720 are respectively constructed on the first branch 71 and the second branch 72 to open and close the gas and liquid flow in the first branch 71 and the second branch 72. Before electrolyte loss is measured and when auxiliary solution needs to be introduced into the collector 1, the first valve 710 on the first branch 71 is closed, at which point the auxiliary solution can only be introduced into the collector 1 from the auxiliary solution storage device 3. When the electrolyte loss is measured, the second valve 720 on the second branch pipe 72 is closed to prevent gas from being transported to the auxiliary solution storage device 3 through the second branch pipe 72, so that the gas can only be transported to the collector 1 through the first branch pipe 71.

[0025] One end of the second conduit 7, connected to the air inlet 111 of the collector 1, extends into the collector 1 and reaches the bottom surface of the collection chamber 11. This ensures that the gas is continuously delivered to the bottom surface 110 of the collection chamber 11, maximizing the gas's residence time in the auxiliary solution. (Reference) Figure 2The diagram shows a schematic bottom view of the collection chamber of the collector of a cell formation liquid loss measuring mechanism according to an embodiment of the present invention. The bottom surface 110 of the collection chamber 11 is designed with a partially horizontal plane and a partially inclined plane. That is, the first region 1101 of the bottom surface 110 of the collection chamber 11, which is directly opposite to the outlet cross-section of the second pipeline 7, is constructed as a plane parallel to the horizontal plane of the auxiliary solution (in this embodiment, the outlet cross-section is circular, so the shape of the first region is also circular. Of course, the outlet cross-section of the second pipeline can also be other shapes, in which case the shape of the first region also corresponds to the shape of the outlet cross-section). The other regions 1102 of the bottom surface 110, excluding the first region 1101, are constructed as inclined planes extending upward from the first region 1101. This allows the auxiliary solution from other regions 1102 to continuously accumulate at the first region 1101 via the inclined surface when the auxiliary solution is discharged from the collector 1 through the second pipe 7. This helps the auxiliary solution to be discharged through the second pipe 7 as much as possible, preventing the auxiliary solution from remaining in the collection chamber 11, especially at the edge of the bottom surface 110 of the collection chamber 11 or in areas far from the first region 1101.

[0026] The steps of the cell formation liquid loss measurement mechanism of the present invention are as follows: First, close the first valve 710 on the first branch pipe 71 and open the second valve 720 on the second branch pipe 72. Input the auxiliary solution into the collector 1 through the auxiliary solution storage device 3 until the amount of auxiliary solution reaches the set value. At the same time, coolant is supplied to the cooling chamber 12 through the cooling device to ensure the cooling of the auxiliary solution. At this time, the volume of the auxiliary solution is collected by the liquid level collector 5 as the first volume. Then, close the second valve 720 on the second branch pipe 72 and open the first valve 710 on the first branch pipe 71 to start the formation. At this time, negative pressure is provided by the negative pressure generating device 2, so that the gas in the cell 200 enters the collector 1 through the second pipe 7 and is discharged through the negative pressure generating device 2 through the first pipe 6. The gaseous or liquid electrolyte in the gas is absorbed by the auxiliary solution in the collector 1. After the formation process is complete, the volume of the auxiliary solution is measured again using the liquid level collector 5 to obtain the second volume. The difference between the second volume and the first volume is calculated, and the difference is multiplied by the density of the electrolyte to obtain the mass of electrolyte lost. After the measurement is completed, the first valve 710 on the first branch pipe 71 is closed, and the second valve 720 on the second branch pipe 72 is opened. The auxiliary solution in the collector 1 is then recovered into the auxiliary solution storage device 3 through the auxiliary solution storage device 3.

[0027] It should be understood that all the above preferred embodiments are exemplary and not restrictive, and various modifications or variations made by those skilled in the art to the specific embodiments described above under the concept of the present invention should be within the legal protection scope of the present invention.

Claims

1. A cell formation liquid loss measuring mechanism, characterized in that, Includes a collector (1) that is permeably connected to the gas of the battery cell (200) undergoing formation, wherein the collector (1) contains an auxiliary solution capable of dissolving the electrolyte in the gas discharged from the battery cell (200); The auxiliary solution is a linear carbonate or alcohol; the loss of electrolyte during the formation process is obtained by the difference in liquid volume of the auxiliary solution before and after formation. The collector (1) has a collection chamber (11) for containing the auxiliary solution and a cooling chamber (12) for containing coolant. The cooling chamber (12) is arranged around the collection chamber (11). The collection chamber (11) has an air inlet (111) and an air outlet (112). The cooling chamber (12) has a coolant inlet (121) and a coolant outlet (122). The cell formation liquid loss measuring mechanism also includes a negative pressure generating device (2). The negative pressure generating device (2) is connected to the outlet (112) of the collector (1) through a first pipeline (6). The inlet (111) of the collector (1) is connected to the cell (200) through a second pipeline (7). The negative pressure generating device (2) draws the gas in the cell (200) into the collector (1) through the first pipeline (6), the collection chamber (11), and the second pipeline (7).

2. The cell formation liquid loss measuring mechanism according to claim 1, characterized in that, The collection chamber (11) is constructed as a cylindrical chamber with a volume greater than or equal to 50 ml, and the ratio of the height of the cylindrical chamber to the diameter of the bottom surface is greater than or equal to 3.

3. The cell formation liquid loss measuring mechanism according to claim 1, characterized in that, The second pipe (7) from the collection chamber room The air inlet (111) of (11) extends into the collector (1) until the collection chamber. room The bottom surface (110) of the bottom surface (110) is configured as a plane parallel to the horizontal plane of the auxiliary solution, and the other areas (1102) of the bottom surface (110) other than the first area (1101) are configured as inclined surfaces extending upward from the first area (1101).

4. The cell formation liquid loss measuring mechanism according to claim 1, characterized in that, A liquid level collector (5) is arranged in the collection chamber (11) for measuring the volume of the auxiliary solution.

5. The cell formation liquid loss measuring mechanism according to claim 1, characterized in that, The cell formation liquid loss measuring mechanism also includes a cooling device, which is connected to the coolant inlet (121) and coolant outlet (122) of the cooling chamber (12) respectively and supplies coolant to the cooling chamber (12).

6. The cell formation liquid loss measuring mechanism according to claim 1, characterized in that, The cell formation liquid loss measuring mechanism also includes an auxiliary solution storage device (3). The second pipeline (7) is branched at one end away from the collector (1) into a first branch pipe (71) and a second branch pipe (72). The first branch pipe (71) is connected to the cell (200), and the second branch pipe (72) is connected to the auxiliary solution storage device (3).

7. The cell formation liquid loss measuring mechanism according to claim 6, characterized in that, Valves are respectively constructed on the first branch pipe (71) and the second branch pipe (72) for opening and cutting off the flow of gas and liquid in the first branch pipe (71) and the second branch pipe (72).

8. The cell formation liquid loss measuring mechanism according to claim 7, characterized in that, The auxiliary solution is dimethyl carbonate, ethyl methyl carbonate, ethanol, or ethylene glycol.

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