Cover plate structure and battery cell

Abstract

The invention relates to the technical field of energy storage equipment, in particular to a cover plate structure and a battery cell, the cover plate structure comprises a top cover, a positive pole and lower plastic, the lower plastic is located on one side, facing the interior of the battery cell, of the top cover, and the lower plastic comprises a positive part. The positive pole penetrates through the first through hole of the positive pole part, the positive pole part is clamped between the top cover and the positive pole bottom plate of the positive pole part, the positive pole part is provided with a communicating hole and a communicating groove which are communicated, the communicating groove is communicated with the inner cavity of the battery cell and the first through hole, and the communicating hole is communicated with the top cover and the positive pole bottom plate. The electrolyte can flow into the communicating hole from the inner cavity of the battery cell through the communicating groove, the top cover and the positive electrode bottom plate can be conducted through the electrolyte, the resistance value of the positive electrode side is greatly reduced, it can be guaranteed that the negative electrode side resistance is higher than the positive electrode side resistance, and the negative electrode side partial voltage is not lower than the corrosion potential of the top cover and the shell, and therefore the lithium embedding corrosion phenomenon is avoided. The battery cell comprises a shell and the cover plate structure, and the cover plate structure covers the opening of the shell in a sealing manner to form a shell of the battery cell.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage equipment, and in particular to a cover plate structure and a battery core. Background Art

[0002] In order to reduce the insulation protection at the module end and reduce the risk of short circuit caused by high-voltage arcing, existing battery cells are generally designed as "neutral shells", that is, the resistance value between the positive and negative poles of the cover structure to the top cover is required to be greater than 200MΩ. However, the "neutral shell" solution often results in the undesirable situation that the voltage on the negative side is lower than the voltage on the positive side, which will cause lithium corrosion of the top cover and the shell and form lithium-aluminum alloy. Summary of the invention

[0003] An object of the present invention is to provide a cover plate structure that can help avoid lithium-embedded corrosion in a top cover and a shell.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] A cover plate structure is provided, comprising a top cover, a positive electrode column and a lower plastic, wherein the lower plastic is located on a side of the top cover facing the inside of a battery cell, the lower plastic comprises a positive electrode portion, the positive electrode column is passed through a first through hole of the positive electrode portion, the positive electrode portion is sandwiched between the top cover and a positive electrode bottom plate of the positive electrode column, the positive electrode portion is provided with a communicating hole and a communicating groove which are connected, the communicating groove can connect the internal cavity of the battery cell and the first through hole, and the communicating hole can connect the top cover and the positive electrode bottom plate.

[0006] Optionally, the connecting groove is provided on the wall surface of the positive electrode portion facing the positive electrode bottom plate, and the width c of the connecting groove satisfies 0.2 mm ≤ c ≤ 5 mm;

[0007] And / or, the connecting groove is formed on the wall surface of the positive electrode portion facing the positive electrode bottom plate, and the depth d of the connecting groove satisfies 0.2 mm≤d≤0.5 mm.

[0008] Optionally, the positive electrode portion is provided with a first limiting groove, the positive electrode bottom plate is located in the first limiting groove, and the first through hole and the connecting hole are both provided at the bottom of the first limiting groove.

[0009] Optionally, the connecting groove includes a first groove and a second groove that are connected to each other, the first groove is opened at the bottom of the first limiting groove, one end of the first groove is connected to the first through hole, the second groove is opened on the side wall of the first limiting groove, and one end of the second groove is connected to the internal cavity of the battery cell.

[0010] Optionally, the length direction of the first groove is parallel to the radial direction of the positive electrode column;

[0011] And / or, the penetration direction of the connecting hole is parallel to the axial direction of the positive electrode column.

[0012] Optionally, a negative electrode column is further included, and the lower plastic also includes a negative electrode part. The negative electrode column is passed through the second through hole of the negative electrode part, and the negative electrode part is clamped between the top cover and the negative electrode bottom plate of the negative electrode column. A ventilation groove is provided on the surface of the negative electrode part close to the top cover, and one end of the ventilation groove is connected to the second through hole, and the lower plastic located around the negative electrode part is attached to the top cover.

[0013] Optionally, the top cover is provided with a second limiting groove, the negative electrode part protrudes from the lower plastic around the negative electrode part toward the top cover, the negative electrode part is located in the second limiting groove, and the ventilation groove is provided on the protruding outer end surface of the negative electrode part.

[0014] Optionally, a negative electrode sealing ring is further included, which is sleeved on the negative electrode column, and the negative electrode sealing ring is at least partially located in the second through hole, and the negative electrode sealing ring can be compressed to fill the space between the inner wall of the second through hole and the side wall of the negative electrode column.

[0015] Optionally, the width a of the vent groove satisfies 0.2 mm ≤ a ≤ 5 mm;

[0016] And / or, the depth b of the ventilation groove satisfies 0.2mm≤b≤0.5mm.

[0017] Another object of the present invention is to provide a battery cell that can help avoid lithium corrosion on the top cover and the shell.

[0018] To achieve this object, the present invention adopts the following technical solutions:

[0019] Provided is a battery cell, comprising a shell and the above-mentioned cover plate structure, wherein the cover plate structure sealing cover is arranged at the opening of the shell to form an outer shell of the battery cell.

[0020] Beneficial effects of the present invention:

[0021] The present invention provides a cover plate structure, including a top cover, a positive electrode column and a lower plastic, wherein the lower plastic is located on the side of the top cover facing the inside of the battery cell, and the lower plastic includes a positive electrode portion. The positive electrode column is inserted through the first through hole of the positive electrode portion, and the positive electrode portion is sandwiched between the top cover and the positive electrode bottom plate of the positive electrode column. The positive electrode portion is provided with a communicating hole and a communicating groove that are connected to each other, and the communicating groove can connect the internal cavity of the battery cell and the first through hole, and the communicating hole can connect the top cover and the positive electrode bottom plate. When the positive electrode is tested for air tightness, if the sealing ring is missing, the gas can reach the internal cavity of the battery cell from the first through hole through the communicating groove, so that the situation that the sealing ring is missing can be discovered in time, and the air tightness test can be achieved. In addition, the electrolyte can flow from the internal cavity of the battery cell through the connecting groove to the connecting hole. The top cover and the positive bottom plate of the pole will be connected through the electrolyte, which greatly reduces the resistance on the positive side, which can help ensure that the resistance of the negative electrode side resistor is higher than the resistance of the positive electrode side resistor, so that the voltage drop on the negative electrode side will not be lower than the corrosion potential of the top cover and the shell, which can help avoid lithium insertion corrosion and ensure the safety of the battery cell.

[0022] The present invention also provides a battery cell, comprising a shell and the above-mentioned cover plate structure, wherein a sealing cover of the cover plate structure is arranged at the opening of the shell to form an outer shell of the battery cell. The battery cell can help to avoid lithium corrosion in the top cover and the shell. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a structural schematic diagram of a cover plate structure provided by an embodiment of the present invention from a first viewing angle;

[0024] Figure 2 is an exploded schematic diagram of a cover plate structure provided by an embodiment of the present invention;

[0025] Figure 3 yes Figure 2 The enlarged view of point A in the middle;

[0026] Figure 4 It is a partial structural schematic diagram of the lower plastic provided by an embodiment of the present invention;

[0027] Figure 5 yes Figure 2 The enlarged view of point B in the middle;

[0028] Figure 6 is a structural schematic diagram of a cover plate structure provided by an embodiment of the present invention from a second viewing angle;

[0029] Figure 7 yes Figure 6 CC section view in;

[0030] Figure 8 yes Figure 7 Enlarged view of point E in the middle;

[0031] Fig. 9 yes Figure 6 DD section view in;

[0032] Fig.10 yes Fig. 9 The enlarged view of F in the middle;

[0033] Fig.11 is a test schematic diagram of the cover plate structure provided by an embodiment of the present invention;

[0034] Fig.12 It is a diagram of element analysis results after testing of the cover plate structure provided by an embodiment of the present invention.

[0035] In the figure:

[0036] 1. Top cover; 11. Second limiting groove;

[0037] 2. Positive electrode column; 21. Positive electrode bottom plate;

[0038] 3. Negative electrode column; 31. Negative electrode bottom plate;

[0039] 4, lower plastic; 41, positive electrode; 411, first through hole; 412, connecting hole; 413, connecting groove; 4131, first groove; 4132, second groove; 414, first limiting groove;

[0040] 42, negative electrode portion; 421, second through hole; 422, ventilation groove; 423, fourth limiting groove;

[0041] 43. Body part;

[0042] 5. Negative electrode sealing ring; 6. Positive electrode sealing ring; 7. Plastic on positive electrode; 8. Plastic on negative electrode; 9. Explosion-proof parts; 10. Explosion-proof patch;

[0043] 100. Cover plate structure; 200. Multimeter; 300. Electrode group. DETAILED DESCRIPTION

[0044] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the above drawings.

[0045] In this application, the terms "comprises", "includes", "has" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0046] In this application, the term "and / or" is a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "and / or" relationship.

[0047] In the present application, the terms "connect", "combine", "couple", and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, direct connection refers to two parts or components being connected together without the need for an intermediate piece, and indirect connection refers to two parts or components being connected to at least one intermediate piece respectively, and the two parts or components being connected via the intermediate piece. In addition, "connect" and "couple" are not limited to physical or mechanical connections or couplings, and may include electrical connections or couplings.

[0048] In the present application, it will be understood by those of ordinary skill in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerances caused by manufacturing, assembly, and use associated with a specific value, and the like. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0049] In this application, it will be understood by those skilled in the art that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0050] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, the bottom can include directly below, lower left, lower right, lower front, and lower back, etc.

[0051] In order to reduce the insulation protection of the module end and reduce the risk of short circuit caused by high-voltage arcing, the existing battery cells are generally designed as "neutral shells", that is, the resistance value between the positive pole column, the negative pole column and the top cover of the cover structure is required to be greater than 200MΩ. However, the "neutral shell" solution often has the undesirable situation that the negative side voltage is lower than the positive side voltage. When the negative side voltage is lower than a certain value, it will cause lithium corrosion of the top cover and the shell, forming lithium-aluminum alloy. The reasons for the above-mentioned side voltage are not only due to the internal pole piece powder and material loss and internal overlap of the battery cell, but also related to the design of the cover structure.

[0052] In order to solve the above problem and avoid lithium-embedded corrosion in the top cover 1 and the shell, this embodiment provides a cover plate structure 100 .

[0053] like Figure 1-Figure 10 As shown, the cover structure 100 of this embodiment includes a top cover 1, a positive electrode column 2, a negative electrode column 3 and a lower plastic 4. The lower plastic 4 is located on the side of the top cover 1 facing the inside of the battery cell. The lower plastic 4 includes a positive electrode portion 41 and a negative electrode portion 42.

[0054] The positive electrode column 2 is passed through the first through hole 411 of the positive electrode portion 41. The positive electrode portion 41 is sandwiched between the top cover 1 and the positive electrode bottom plate 21 of the positive electrode column 2. The positive electrode portion 41 is provided with a communicating hole 412 and a communicating groove 413. The communicating groove 413 can communicate the internal cavity of the battery cell with the first through hole 411, and the communicating hole 412 can communicate the top cover 1 with the positive electrode bottom plate 21. When the positive electrode is tested for air tightness, if the sealing ring is missing, the gas can reach the internal cavity of the battery cell from the first through hole 411 through the communicating groove 413, so that the situation that the sealing ring is missing can be found in time, and the air tightness test can be achieved. In addition, the electrolyte can flow from the internal cavity of the battery cell through the connecting groove 413 to the connecting hole 412. The top cover 1 and the positive bottom plate 21 of the positive electrode column 2 will be connected through the electrolyte, which greatly reduces the resistance on the positive electrode side, which can help ensure that the resistance of the negative electrode side resistor is higher than the resistance of the positive electrode side resistor, so that the voltage drop on the negative electrode side will not be lower than the corrosion potential of the top cover 1 and the shell, which can help avoid lithium insertion corrosion and ensure the safety of the battery cell.

[0055] like Figure 4 and Figure 8 As shown, optionally, the positive electrode portion 41 is provided with a first limiting groove 414, the positive electrode bottom plate 21 is located in the first limiting groove 414, and the first through hole 411 and the connecting hole 412 are both provided at the bottom of the first limiting groove 414 to ensure that one end opening of the connecting hole 412 is directly located on the end surface of the positive electrode bottom plate 21 facing the top cover 1.

[0056] like Figure 4 As shown, optionally, the connecting groove 413 includes a first groove 4131 and a second groove 4132 that are connected to each other, the first groove 4131 is opened at the bottom of the first limiting groove 414, and one end of the first groove 4131 is connected to the first through hole 411. Optionally, in this embodiment, one end of the first groove 4131 is opened through. The second groove 4132 is opened on the side wall of the first limiting groove 414, and one end of the second groove 4132 is connected to the internal cavity of the battery cell. That is, the connecting groove 413 is entirely opened on the surface of the positive electrode part 41 to facilitate processing. Of course, in other embodiments, the connecting groove 413 can also be arranged inside the positive electrode part 41, as long as one end is connected to the first through hole 411 and the other end is connected to the internal cavity of the battery cell, and it needs to be arranged to intersect with the connecting hole 412.

[0057] Optionally, in this embodiment, the connecting hole 412 is connected to the first groove 4131, that is, the connecting hole 412 is opened at the bottom of the first groove 4131. And the groove width of the first groove 4131 is greater than the diameter of the connecting hole 412, so as to ensure that the electrolyte quickly passes through the first groove 4131 into the connecting hole 412.

[0058] Optionally, the length direction of the first groove 4131 is parallel to the radial direction of the positive electrode column 2 so that the distance between the two ends of the first groove 4131 is the shortest, which can prevent the first groove 4131 from being too long. Since the material of the lower plastic 4 has a certain elasticity, the middle part of the first groove 4131 is squeezed, and the bottom of the groove abuts against the positive electrode bottom plate 21, causing the ventilation function to fail.

[0059] Optionally, the penetrating direction of the connecting hole 412 is parallel to the axial direction of the positive electrode column 2 to minimize the length of the connecting hole 412, thereby shortening the time required for electrolyte filling and conducting the positive electrode bottom plate 21 and the top cover 1, thereby achieving rapid conduction.

[0060] Once the free electrolyte inside the battery cell flows in through the gap of the cover structure 100, an electrolyte passage is formed between the top cover 1 and the negative electrode column 3, which will also lower the voltage on the negative electrode side. However, in order to facilitate the airtightness detection of the cover structure 100 to determine whether the negative electrode sealing ring 5 is missing, it is necessary to open a through groove on the negative electrode side of the lower plastic 4 for ventilation, so that when the sealing ring 5 is missing, the air flow can reach the outside of the battery cell through the through groove and the gap between the negative electrode column 3 and the top cover 1, and the leakage is detected. When the sealing ring 5 is assembled normally, the gap between the negative electrode column 3 and the top cover 1 is completely blocked, and the air flow will not be able to pass, thereby confirming that the sealing ring 5 is assembled normally. Therefore, in order to simplify the detection of whether the sealing ring 5 is missing, it is necessary to open a through groove on the negative electrode side of the lower plastic 4. However, the design of opening a through groove on the negative electrode side of the lower plastic 4 is likely to cause the electrolyte in the battery cell to flow into the gap between the negative electrode column 3 and the top cover 1, so that the negative electrode column 3 and the top cover 1 are connected, resulting in a decrease in the voltage on the negative electrode side. When the voltage on the positive electrode side is equivalent to the voltage on the negative electrode side, after long-term use, once the electrolyte in the connecting hole on the positive electrode side crystallizes, there is still a risk of lithium insertion corrosion.

[0061] In order to circumvent the above problems, optionally, the negative pole 3 is passed through the second through hole 421 of the negative portion 42, the negative portion 42 is sandwiched between the top cover 1 and the negative bottom plate 31 of the negative pole 3, and a ventilation groove 422 is provided on the surface of the negative portion 42 close to the top cover 1, one end of the ventilation groove 422 is connected to the second through hole 421, and the lower plastic 4 located around the negative portion 42 is attached to the top cover 1. When the air tightness test of the negative electrode is performed, if the sealing ring is missing, the gas can reach the position where the lower plastic 4 is attached to the top cover 1 from the second through hole 421 through the ventilation groove 422. Since the gas has a certain air pressure, it will break the position where the lower plastic 4 and the top cover 1 are tightly attached to form a gap. The gas will reach the edge of the lower plastic 4 through the gap, that is, enter the internal cavity of the battery cell, so that the situation of missing sealing ring can be discovered in time, and the air tightness test can be achieved. The electrolyte will not rush out of the gap like gas, and the probability of the electrolyte entering the ventilation groove 422 is very low, which can prevent the resistance of the negative electrode side resistor from decreasing. Since the resistance of the positive electrode side resistor of the cover plate structure 100 is extremely low, it can ensure that the resistance of the negative electrode side resistor is higher than the resistance of the positive electrode side resistor, thereby ensuring that the voltage drop on the negative electrode side will never be lower than the corrosion potential of the top cover 1 and the shell, thereby completely avoiding the occurrence of lithium insertion corrosion and ensuring the safety of the battery cell.

[0062] like Fig.10 As shown, optionally, in order to prevent the negative electrode portion 42 from being misaligned with the top cover 1, the top cover 1 is provided with a second limiting groove 11, and the negative electrode portion 42 protrudes toward the top cover 1 from the lower plastic 4 around the negative electrode portion 42. In this embodiment, in addition to the positive electrode portion 41 and the negative electrode portion 42, the lower plastic 4 also includes a body portion 43, and the area around the negative electrode portion 42 is the area of ​​the body portion 43. The negative electrode portion 42 protrudes toward the top cover 1 compared to the body portion 43, and the negative electrode portion 42 is located in the second limiting groove 11, as shown in FIG. Figure 5 As shown, the vent groove 422 is provided on the protruding outer end surface of the negative electrode portion 42. This arrangement can facilitate the processing of the vent groove 422. Optionally, the bottom of the vent groove 422 is still higher than the height of the main body portion 43, that is, the processing of the vent groove 422 does not need to avoid the area of ​​the main body portion 43, which can improve the processing efficiency.

[0063] Optionally, in order to prevent misalignment between the positive electrode portion 41 and the top cover 1, in this embodiment, the top cover 1 is further provided with a third limiting groove, the positive electrode portion 41 protrudes from the surrounding main body portion 43, and the positive electrode portion 41 is arranged in the third limiting groove.

[0064] Optionally, in order to prevent the negative electrode portion 42 from being misaligned with the negative electrode bottom plate 31, in the present embodiment, a fourth limiting groove 423 is provided on the side of the negative electrode portion 42 facing the inside of the battery cell, the negative electrode bottom plate 31 is located in the fourth limiting groove 423, and the second through hole 421 is provided at the bottom of the fourth limiting groove 423. The bottom of the fourth limiting groove 423 is close to the negative electrode bottom plate 31 to prevent the electrolyte from penetrating therefrom. Optionally, the negative electrode bottom plate 31 is a square plate-shaped structure, and the four corners are all rounded, and accordingly, the fourth limiting groove 423 is also a square groove, and the four sides are all rounded.

[0065] Optionally, the ventilation groove 422 is opened through the radial direction of the negative pole 3 to prevent the lower plastic 4 from being squeezed, and the bottom of the ventilation groove 422 is close to the top cover 1, causing the airtightness detection to fail.

[0066] Optionally, the cover plate structure 100 also includes a negative electrode sealing ring 5, which is sleeved on the negative electrode column 3. The negative electrode sealing ring 5 is at least partially located in the second through hole 421. The negative electrode sealing ring 5 can be compressed to fill the space between the inner wall of the second through hole 421 and the side wall of the negative electrode column 3, which can further prevent the electrolyte from entering the space between the inner wall of the second through hole 421 and the side wall of the negative electrode column 3, and conduct the negative electrode bottom plate 31 and the top cover 1. Therefore, the negative electrode sealing ring 5 has the function of further preventing the negative electrode side resistance from decreasing, ensuring that the resistance of the negative electrode side resistance is always higher than the resistance of the positive electrode side resistance, thereby better preventing the problem of lithium insertion corrosion.

[0067] Optionally, in this embodiment, a plurality of connecting holes 412 and connecting grooves 413 are provided, and the plurality of connecting holes 412 are provided in one-to-one correspondence with the plurality of connecting grooves 413. The openings of the plurality of connecting grooves 413 connecting the internal cavities of the battery cells are evenly arranged along the circumferential intervals of the positive electrode column 2 to prevent the electrolyte from being unable to enter the connecting grooves 413 somewhere, resulting in the inability of the positive electrode bottom plate 21 to quickly conduct with the top cover 1.

[0068] Of course, in other embodiments, the positive electrode portion 41 is provided with another connecting hole 412, which is not connected to the connecting groove 413. On the one hand, the number of connecting holes 412 can be increased to further ensure a rapid decrease in the positive electrode side resistance. On the other hand, too many connecting grooves 413 can be prevented from being opened, resulting in insufficient structural strength of the positive electrode portion 41.

[0069] In other embodiments, multiple smaller connecting holes 412 may be arranged to connect to the same connecting groove 413 . The actual size, number and arrangement of the connecting holes 412 may be designed and adjusted according to the actual size of the positive electrode portion 41 .

[0070] Optionally, a plurality of ventilation grooves 422 are provided, and the openings of the plurality of ventilation grooves 422 communicating with the second through hole 421 are evenly spaced along the circumference of the negative electrode column 3 to ensure the accuracy of the airtightness test.

[0071] Optionally, the width a of the vent groove 422 satisfies 0.2mm≤a≤5mm. If the width a of the vent groove 422 is less than 0.2mm, the difficulty of mold processing is too great, and the ventilation effect is poor during the air tightness test, and the normal progress of the air tightness test cannot be guaranteed, which is prone to omissions. If the width a of the vent groove 422 is greater than 5mm, the strength of the negative electrode portion 42 will be affected, the bottom of the vent groove 422 will easily abut the top cover 1, and the overall shape of the negative electrode portion 42 will easily change, so that the negative electrode portion 42 is easily misaligned compared to the top cover 1, resulting in the quality of the battery cell cannot be guaranteed.

[0072] Optionally, the depth b of the vent groove 422 satisfies 0.2mm≤b≤0.5mm. If the depth b of the vent groove 422 is less than 0.2mm, the lower plastic 4 will also be slightly compressed, but the exhaust effect is not good, and the accuracy of the airtightness test cannot be guaranteed. If the depth b of the vent groove 422 is greater than 0.5mm, the strength of the negative electrode part 42 will also be affected, and the negative electrode part 42 is easily misaligned compared to the top cover 1, resulting in the quality of the battery cell cannot be guaranteed.

[0073] Optionally, the connecting groove 413 is provided on the wall surface of the positive electrode portion 41 facing the positive electrode bottom plate 21, and the width c of the connecting groove 413 satisfies 0.2mm≤c≤5mm. If the width c of the connecting groove 413 is less than 0.2mm, the difficulty of mold processing is too great, and the ventilation effect is not good during the air tightness test, and the normal progress of the air tightness test cannot be guaranteed, and the problem of missed inspection is prone to occur. If the width c of the connecting groove 413 is greater than 5mm, the strength of the positive electrode portion 41 will be affected, the bottom of the connecting groove 413 will easily abut the top cover 1, and the overall shape of the positive electrode portion 41 will easily change, so that the positive electrode portion 41 is easily misaligned compared to the top cover 1, resulting in the quality of the battery cell cannot be guaranteed.

[0074] Optionally, the connecting groove 413 is provided on the wall of the positive electrode portion 41 facing the positive electrode bottom plate 21, and the depth d of the connecting groove 413 satisfies 0.2mm≤d≤0.5mm. If the depth d of the connecting groove 413 is less than 0.2mm, the lower plastic 4 will also be slightly compressed, but the exhaust effect is not good, and the accuracy of the airtightness test cannot be guaranteed. If the depth d of the connecting groove 413 is greater than 0.5mm, the strength of the positive electrode portion 41 will also be affected, and the positive electrode portion 41 is easily misaligned compared to the top cover 1, resulting in the quality of the battery cell cannot be guaranteed.

[0075] In order to verify the effectiveness of the cover plate structure 100 in solving the lithium corrosion problem of the top cover 1 and the shell, Fig.11As shown in Table 1, this embodiment provides a set of detection records, which include the positive electrode side resistance and voltage and the negative electrode side resistance and voltage. In order to simulate the actual battery cell, during the detection process, it is necessary to continuously titrate the electrolyte to the positive and negative sides of the cover plate structure 100. The specific position of the positive side titration is at the gap between the side wall of the positive bottom plate 21 and the side wall of the first limiting groove 414, that is, the opening where the second groove 4132 is connected to the internal cavity of the battery cell, and the specific position of the negative side titration is at the gap between the side wall of the negative bottom plate 31 and the side wall of the fourth limiting groove 423. The positive side and the negative side are titrated at the same time, and the positive pole column 2 is connected to the positive pole ear of the pole group 300, and the negative pole column 3 is connected to the negative pole ear of the pole group 300. When the titration reaches two hours, four hours, eight hours, twelve hours, twenty-four hours, forty-eight hours, seventy-two hours, and one hundred and sixty-eight hours, a multimeter 200 is used for detection. Contact the two test terminals of the multimeter 200 to the top cover 1 and the positive pole 2 respectively, and record the resistance and voltage of the positive pole. At the same time, contact the two test terminals of another multimeter 200 to the top cover 1 and the negative pole 3 respectively, and record the resistance and voltage of the negative pole. The test results are shown in the following table.

[0076] Table 1

[0077]

[0078]

[0079] It can be seen from the measured data that after two hours of titrating the electrolyte on the positive electrode side, the voltage on the positive electrode side suddenly dropped to below 0.5V, and the resistance on the positive electrode side also dropped significantly. At the same time, the voltage on the negative electrode side did not change significantly, and the resistance on the negative electrode side also remained above 200MΩ. Obviously, the resistance on the positive electrode side is much smaller than that on the negative electrode side. And as time goes by, the resistance value of the positive electrode side resistor fluctuates slightly, but there is no obvious recovery, and it is still much lower than the resistance value of the negative electrode side resistor, and the resistance and voltage on the negative electrode side are relatively stable. It can be seen that the cover plate structure 100 can ensure that the resistance value of the negative electrode side resistor is higher than the resistance value of the positive electrode side resistor, thus ensuring that the partial pressure on the negative electrode side will never be lower than the corrosion potential of the top cover 1 and the shell, thereby preventing the problem of lithium insertion corrosion, so that the battery cell continues to have a high safety.

[0080] In addition, an element analysis instrument can be used to detect whether there are electrolyte elements on the negative electrode sealing ring 5, so as to determine whether the electrolyte has entered the second through hole 421. The lithium salt in the electrolyte is lithium hexafluorophosphate, which contains the P element. Fig.12 As shown, no P element is found on the negative electrode sealing ring 5, which proves that there is no electrolyte residue on the negative electrode sealing ring 5 and no electrolyte infiltration on the negative electrode side, that is, the electrolyte will not conduct the negative electrode bottom plate 31 and the top cover 1, thereby reducing the negative electrode side resistance. The test result further confirms the reliability of the cover plate structure 100 design.

[0081] Optionally, in this embodiment, the cover plate structure 100 further includes a positive electrode sealing ring 6, a positive electrode upper plastic 7, and a negative electrode upper plastic 8. The positive electrode sealing ring 6 is sleeved on the positive electrode column 2, and the positive electrode sealing ring 6 is at least partially located in the first through hole 411, and the positive electrode sealing ring 6 can be compressed to fill the space between the inner wall of the first through hole 411 and the side wall of the positive electrode column 2. The positive electrode upper plastic 7 is sleeved on the positive electrode column 2, and is used to space the positive electrode column 2 from the upper end surface of the top cover 1 to ensure insulation between the positive electrode column 2 and the top cover 1. The negative electrode upper plastic 8 is sleeved on the negative electrode column 3, and is used to space the negative electrode column 3 from the upper end surface of the top cover 1 to ensure insulation between the negative electrode column 3 and the top cover 1.

[0082] Optionally, in this embodiment, the cover structure 100 further includes an explosion-proof component 9 and an explosion-proof patch 10. The explosion-proof component 9 is arranged at the explosion-proof through hole of the top cover 1, and the explosion-proof patch 10 is arranged on the outward side of the explosion-proof component 9 to protect the explosion-proof component 9.

[0083] This embodiment also provides a battery cell, including a shell and the above-mentioned cover plate structure 100, the cover plate structure 100 is sealed and arranged at the opening of the shell to form the shell of the battery cell. The electrode group 300, the insulating film, etc. of the battery cell are all arranged in the shell of the battery cell.

[0084] The battery cell can prevent the top cover 1 and the shell from lithium-embedded corrosion while meeting the airtightness test of the cover plate structure 100 .

[0085] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Cover plate structure, characterized in that: The invention comprises a top cover (1), a positive electrode column (2) and a lower plastic (4), wherein the lower plastic (4) is located on a side of the top cover (1) facing the inside of the battery cell, the lower plastic (4) comprises a positive electrode portion (41), the positive electrode column (2) is inserted through a first through hole (411) of the positive electrode portion (41), the positive electrode portion (41) is sandwiched between the top cover (1) and a positive electrode bottom plate (21) of the positive electrode column (2), the positive electrode portion (41) is provided with a communicating hole (412) and a communicating groove (413) which are connected to each other, the communicating groove (413) can connect the internal cavity of the battery cell and the first through hole (411), and the communicating hole (412) can connect the top cover (1) and the positive electrode bottom plate (21).

2. The cover plate structure according to claim 1, characterized in that: The connecting groove (413) is provided on the wall surface of the positive electrode portion (41) facing the positive electrode bottom plate (21), and the width c of the connecting groove (413) satisfies 0.2 mm ≤ c ≤ 5 mm; And / or, the connecting groove (413) is provided on the wall surface of the positive electrode portion (41) facing the positive electrode bottom plate (21), and the depth d of the connecting groove (413) satisfies 0.2 mm ≤ d ≤ 0.5 mm.

3. The cover plate structure according to claim 1, characterized in that: The positive electrode portion (41) is provided with a first limiting groove (414), the positive electrode bottom plate (21) is located in the first limiting groove (414), and the first through hole (411) and the connecting hole (412) are both provided at the bottom of the first limiting groove (414).

4. The cover plate structure according to claim 3, characterized in that: The connecting groove (413) comprises a first groove (4131) and a second groove (4132) which are connected to each other, wherein the first groove (4131) is provided at the groove bottom of the first limiting groove (414), one end of the first groove (4131) is connected to the first through hole (411), and the second groove (4132) is provided on the side wall of the first limiting groove (414), and one end of the second groove (4132) is connected to the internal cavity of the battery cell.

5. The cover plate structure according to claim 4, characterized in that: The length direction of the first groove (4131) is parallel to the radial direction of the positive electrode column (2); And / or, the penetration direction of the connecting hole (412) is parallel to the axial direction of the positive electrode column (2).

6. The cover plate structure according to any one of claims 1 to 5, characterized in that: It also includes a negative pole column (3), the lower plastic (4) also includes a negative pole part (42), the negative pole column (3) is inserted into the second through hole (421) of the negative pole part (42), the negative pole part (42) is sandwiched between the top cover (1) and the negative pole bottom plate (31) of the negative pole column (3), a ventilation groove (422) is provided on the surface of the negative pole part (42) close to the top cover (1), one end of the ventilation groove (422) is connected to the second through hole (421), and the lower plastic (4) located around the negative pole part (42) is attached to the top cover (1).

7. The cover plate structure according to claim 6, characterized in that: The top cover (1) is provided with a second limiting groove (11), the negative electrode part (42) protrudes from the lower plastic (4) around the negative electrode part (42) toward the top cover (1), the negative electrode part (42) is located in the second limiting groove (11), and the ventilation groove (422) is provided on the protruding outer end surface of the negative electrode part (42).

8. The cover plate structure according to claim 6, characterized in that: It also comprises a negative electrode sealing ring (5), which is sleeved on the negative electrode column (3), and the negative electrode sealing ring (5) is at least partially located in the second through hole (421), and the negative electrode sealing ring (5) can be compressed to fill the space between the inner wall of the second through hole (421) and the side wall of the negative electrode column (3).

9. The cover plate structure according to claim 6, characterized in that: The width a of the vent groove (422) satisfies 0.2 mm ≤ a ≤ 5 mm; And / or, the depth b of the ventilation groove (422) satisfies 0.2 mm ≤ b ≤ 0.5 mm.

10. A battery cell, characterized in that: It comprises a shell and a cover plate structure as claimed in any one of claims 1 to 9, wherein the cover plate structure (100) is sealed and arranged at the opening of the shell to form an outer shell of the battery cell.

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