Square three-electrode battery top cover and square three-electrode battery

Abstract

The utility model relates to the technical field of batteries, and discloses a square three-electrode battery top cover and a square three-electrode battery, the square three-electrode battery top cover comprises a top cover plate, a positive pole column, a reference pole column, an explosion-proof valve, a liquid injection hole, a negative pole column, upper plastic cement and lower plastic cement, the positive pole column, the reference pole column, the explosion-proof valve, the liquid injection hole and the negative pole column are arranged on the top cover plate at intervals; the reference pole columns comprise an upper reference pole column and a lower reference pole column, the upper reference pole column is arranged on the outer side of the top cover plate, the lower reference pole column is arranged on the inner side of the top cover plate, and the upper reference pole column and the lower reference pole column are oppositely arranged and electrically connected; the reference upper pole is insulated and sealed with the top cover plate through upper plastic, and the reference lower pole is insulated and sealed with the top cover plate through lower plastic. According to the square three-electrode battery top cover, the function of the anti-explosion valve can be prevented from being influenced, the liquid leakage risk of the battery is avoided, the connecting part of the reference electrode is not led out of the battery, the reference electrode is prevented from being exposed, additional protection measures are not needed, the fracture risk of the reference electrode is avoided, and the yield of finished batteries is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a square three-electrode battery top cover and a square three-electrode battery. Background Art

[0002] As one of the components of the three-electric system of electric vehicles, power batteries have become a core component in the electric vehicle platform architecture and play a vital role in the "fast charging revolution" of electric vehicles. Fast charging relies on high charging rates. Due to the influence of diffusion and charge transfer dynamics, lithium plating becomes the side reaction with the greatest impact on fast charging of lithium-ion batteries. At the same time, as the charging rate increases, the battery generates more heat and it is difficult to dissipate it quickly and evenly, resulting in local high temperatures and uneven temperature field distribution, which accelerates battery performance degradation and even causes safety problems such as thermal runaway. Among them, the occurrence of lithium plating side reaction is affected by many factors, including battery parameters, aging status, rate and temperature rise during charging process. It is unreasonable to use charging strategy in high temperature zone, especially high energy density battery, which is more prone to lithium plating when charging at high rate. Monitoring the occurrence of negative electrode lithium plating side reaction is the key point to realize fast charging technology. In this regard, three-electrode technology is one of the commonly used methods for fast charging system design verification and fast charging strategy development. Implanting a reference electrode in the battery to construct a three-electrode system can realize real-time monitoring of negative electrode lithium plating side reaction. In addition to forming a normal working circuit by passing current between the positive electrode (working electrode) and the negative electrode (auxiliary electrode), the negative electrode is used as the second working electrode and the reference electrode as a test circuit. The current in this circuit is extremely small, which is used to realize the monitoring of the negative electrode potential.

[0003] During fast charging, the current density and heat generation rate vary at different locations in the battery, as do the uneven distribution of temperature fields and heat dissipation due to the different sizes and structural designs of pouch cells and cylindrical batteries. These inconsistencies are further amplified in large-scale prismatic batteries, making the verification of fast-charging strategies and the research of fast-charging lithium deposition more complex. Unlike the three-electrode manufacturing of pouch cells, prismatic batteries use an aluminum shell design. To ensure the battery's tightness, the reference electrode cannot be directly introduced from the battery through any opening like in pouch cells, making manufacturing more complex. In the traditional three-electrode production of square batteries, the reference electrode is usually led out from the explosion-proof valve by breaking the valve, and then cured and sealed with epoxy resin glue. However, this solution has many disadvantages. For example, when the reference electrode is led out from the explosion-proof valve, the function of the explosion-proof valve is weakened, and the safety is reduced under extreme test conditions such as high temperature and high-rate lithium deposition. When the reference electrode is led out from the explosion-proof valve, an opening needs to be set, and the opening needs to be sealed with epoxy resin glue. If the epoxy resin glue is not completely sealed, the rapid heat release during the curing process will cause pores inside the glue, which can easily increase the risk of leakage during the process. At the same time, the stability of the epoxy resin glue under extreme conditions such as low and high temperatures will also be affected, increasing the risk of leakage. After the reference electrode is led out, additional protection is required. The laser welding of the top cover in the subsequent process can easily burn the reference electrode or cause the top cover welding to be poorly welded. In addition, after the battery is assembled, the reference electrode is exposed to the outside, and the subsequent multiple steps of the battery process can easily cause the reference electrode to break, affecting the yield of the finished battery.

[0004] Therefore, how to rationally design the reference electrode of the square battery to alleviate the defects of the current reference electrode setting is an urgent problem that needs to be solved. Utility Model Content

[0005] The purpose of the present utility model is to provide a square three-electrode battery top cover and a square three-electrode battery. In the square three-electrode battery top cover, a reference pole is provided to be connected to the reference electrode to realize the connection setting between the reference electrode and the outside of the battery, which not only avoids the impact on the function of the explosion-proof valve and avoids the risk of battery leakage, but also prevents the connection part of the reference electrode from being led out of the battery to avoid the reference electrode being exposed to the outside, so that no additional protective measures are required, and the risk of reference electrode breaking is avoided, which is conducive to ensuring the yield of the finished battery.

[0006] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions:

[0007] A square three-electrode battery top cover comprises: a top cover plate, a positive electrode column, a reference electrode column, an explosion-proof valve, a liquid injection hole and a negative electrode column arranged on the top cover plate and spaced apart, as well as an upper plastic and a lower plastic; wherein,

[0008] The reference electrode includes: a reference upper electrode and a reference lower electrode, the reference upper electrode is arranged on the outside of the top cover plate, and the reference lower electrode is arranged on the inside of the top cover plate, the reference upper electrode and the reference lower electrode are arranged opposite to each other and electrically connected, and the reference lower electrode is used to connect to the reference electrode; the reference upper electrode is insulated and sealed from the top cover plate by the upper plastic, and the reference lower electrode is insulated and sealed from the top cover plate by the lower plastic.

[0009] In the above-mentioned square three-electrode battery top cover, an independent reference electrode is provided on the top cover plate, and the reference electrode of the battery cell is directly connected to the reference electrode. The reference electrode does not need to be led out at the explosion-proof valve, thereby not adversely affecting the function of the explosion-proof valve, so that the function of the explosion-proof valve remains good, and safety is guaranteed during testing under extreme test conditions such as high temperature and high-rate lithium deposition. Moreover, since the reference electrode is not led out at the explosion-proof valve, there is no need to set a lead-out opening at the position where the explosion-proof valve is installed on the top cover plate, and there is no need for a sealant such as epoxy resin glue to seal the lead-out hole, thereby avoiding the risk of leakage caused by incomplete sealing of the sealant and the risk of leakage caused by the stability of the sealant under extreme test conditions such as low temperature and high temperature. In addition, the reference electrode is fixed on the top cover plate, which enables the reference electrode to be electrically connected to the components outside the battery. The reference electrode does not need to be exposed, and the reference electrode does not need additional protection. After the battery is assembled, the reference electrode will not be easily broken or damaged during the subsequent flow of other processes, which is conducive to improving the yield of the finished battery.

[0010] Therefore, in the above-mentioned square three-electrode battery top cover, a reference pole is provided to be connected to the reference electrode to realize the connection setting between the reference electrode and the outside of the battery, which not only avoids the impact on the function of the explosion-proof valve and the risk of battery leakage, but also prevents the connection part of the reference electrode from being led out of the battery, avoiding the reference electrode from being exposed to the outside, so there is no need for additional protective measures, and avoids the risk of reference electrode breakage, which is conducive to ensuring the yield of the finished battery.

[0011] Optionally, the reference lower electrode has a fixing hole on a side facing away from the reference upper electrode, and an insulating plug for cooperating with the fixing hole, the fixing hole is used for one end of the reference electrode to extend into, and when one end of the reference electrode extends into the fixing hole, the insulating plug is used to clamp and fix the end of the reference electrode;

[0012] A welding area for welding with the reference electrode is formed on a surface of the reference lower pole facing away from the reference upper pole.

[0013] Optionally, in a direction perpendicular to the top cover plate, the orthographic projection of the reference upper pole covers the orthographic projection of the reference lower pole.

[0014] Optionally, in a direction perpendicular to the top cover plate, the area of ​​the orthographic projection of the reference electrode is smaller than the area of ​​the orthographic projection of the positive electrode, and smaller than the area of ​​the orthographic projection of the negative electrode.

[0015] Optionally, the positive electrode column includes: a positive electrode upper column and a positive electrode lower column, the positive electrode upper column is arranged on the outside of the top cover plate, the positive electrode lower column is arranged on the inside of the top cover plate, the positive electrode upper column and the positive electrode lower column are arranged opposite to each other and electrically connected, and the positive electrode lower column is used to connect to the positive electrode tab;

[0016] The negative electrode column includes: a negative electrode upper column and a negative electrode lower column, the negative electrode upper column is arranged on the outside of the top cover plate, the negative electrode lower column is arranged on the inside of the top cover plate, the negative electrode upper column and the negative electrode lower column are arranged opposite to each other and electrically connected, and the negative electrode lower column is used to connect to the negative electrode ear;

[0017] The positive upper pole and the negative upper pole are both insulated and sealed from the top cover plate by the upper plastic; the positive lower pole and the negative lower pole are both insulated and sealed from the top cover plate by the lower plastic.

[0018] Optionally, in a direction perpendicular to the top cover plate, the orthographic projection of the positive upper pole covers the orthographic projection of the positive lower pole, and the orthographic projection of the negative upper pole covers the orthographic projection of the negative lower pole.

[0019] Optionally, the positive electrode column, the reference electrode column, the explosion-proof valve, the liquid injection hole and the negative electrode column are sequentially spaced apart in a first direction parallel to the top cover plate.

[0020] This solution also provides a square three-electrode battery, comprising any square three-electrode battery top cover provided by the above technical solution, a shell, and a three-electrode battery cell arranged in the shell, wherein the square three-electrode battery top cover is used to close the opening on the top side of the shell;

[0021] The top side of the three-electrode battery cell has a positive tab, a negative tab and a connection portion of a reference electrode, the positive tab is connected to the positive electrode post, the negative tab is connected to the negative electrode post, and the connection portion of the reference electrode is connected to the reference lower post.

[0022] Optionally, the side of the reference lower electrode of the square three-electrode battery top cover facing away from the reference upper electrode has a fixing hole and an insulating plug for cooperating with the fixing hole, and the surface of the reference lower electrode facing away from the reference upper electrode has a welding area for welding to the reference electrode;

[0023] The free end of the connecting portion of the reference electrode extends into the fixing hole and is electrically connected to the reference lower electrode. The insulating plug is filled in the fixing hole to fix the free end of the connecting portion of the reference electrode; and a portion of the connecting portion contacts and is welded to the welding area of ​​the reference lower electrode.

[0024] Optionally, the three-electrode battery cell includes: a negative electrode sheet, a positive electrode sheet and a reference electrode that are stacked and isolated from each other, and a diaphragm is provided between two adjacent ones of the negative electrode sheet, the positive electrode sheet and the reference electrode; the positive electrode ear is formed on the top side of the positive electrode sheet, the negative electrode ear is formed on the top side of the negative electrode sheet, and the connecting portion is formed on the top side of the reference electrode.

[0025] Optionally, the reference electrode is a copper wire, and at least a portion of the copper wire exposed inside the shell is covered with an insulating layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings constituting part of this application are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an improper limitation of the present invention.

[0027] Figure 1 A schematic structural diagram of a three-electrode battery provided in a comparative example;

[0028] Figure 2 Schematic diagram of the structure of a three-electrode battery provided in this embodiment;

[0029] Figure 3 A partial perspective structural diagram of a three-electrode battery provided in this embodiment;

[0030] Figure 4 This is a schematic top view of a square three-electrode battery top cover provided in this embodiment;

[0031] Figure 5 This is a bottom view of a square three-electrode battery top cover provided in this embodiment;

[0032] Figure 6 A schematic side view of a square three-electrode battery top cover provided in this embodiment;

[0033] Figure 7 This is a bottom-up schematic diagram of a reference lower pole provided in this embodiment;

[0034] Figure 8 This is a schematic diagram of the structure of the connection between a reference lower pole and a reference electrode provided in this embodiment;

[0035] Figure 9Schematic diagram of a three-electrode battery cell structure provided in this embodiment.

[0036] Icons: 1-square three-electrode battery top cover; 2-shell; 3-three-electrode battery cell; 11-top cover plate; 12-positive electrode column; 13-reference electrode column; 14-explosion-proof valve; 15-liquid filling hole; 16-negative electrode column; 17-upper plastic; 18-lower plastic; 31-negative electrode sheet; 32-positive electrode sheet; 33-reference electrode; 34-diaphragm; 121-positive electrode upper column; 122-positive electrode lower column; 131-reference electrode upper column; 132-reference electrode lower column; 161-negative electrode upper column; 162-negative electrode lower column; 311-negative electrode ear; 321-positive electrode ear; 1321-fixing hole; 1322-insulating plug. DETAILED DESCRIPTION

[0037] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with examples. Each example is provided by way of explanation of the present invention and does not limit the present invention. In fact, it will be clear to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as part of one embodiment can be used in another embodiment to produce yet another embodiment. Therefore, it is intended that the present invention encompass such modifications and variations as come within the scope of the appended claims and their equivalents.

[0038] In the description of the present invention, the terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present invention. The terms "connected", "connected", and "set" used in the present invention should be understood in a broad sense. For example, they can be fixed connections or detachable connections; they can be directly connected or indirectly connected through intermediate components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0039] refer to Figure 2 、 Figure 3 ,as well as Figure 4 and Figure 5As shown, the embodiment of the present invention provides a square three-electrode battery top cover, comprising: a top cover plate 11, a positive electrode column 12, a reference electrode column 13, an explosion-proof valve 14, a liquid injection hole 15 and a negative electrode column 16 arranged on the top cover plate 11 and spaced apart, as well as an upper plastic 17 and a lower plastic 18. The top cover plate 11 is used to cover the shell 2 of the square three-electrode battery. The side of the top cover plate 11 facing the interior of the shell 2 is the inner side of the top cover plate 11, and the side of the top cover plate 11 facing away from the interior of the shell 2 is the outer side of the top cover plate 11; wherein, as shown in FIG. Figure 6 As shown, the reference pole 13 includes: a reference upper pole 131 and a reference lower pole 132, the reference upper pole 131 is arranged on the outside of the top cover plate 11, and the reference lower pole 132 is arranged on the inside of the top cover plate 11. A reference opening for installing the reference pole 13 is provided on the top cover plate 11, and the reference upper pole 131 and the reference lower pole 132 are arranged opposite to each other at the reference opening. The reference upper pole 131 is installed at the reference opening on the outside of the top cover plate 11, and the reference lower pole 132 is installed at the reference opening on the inside of the top cover plate 11. The reference upper pole 131 and the reference lower pole 132 are pressed up and down. The contact is fixed and the electrical connection is achieved. The reference lower pole 132 can be connected to the reference electrode 33 of the battery cell in the shell 2. Specifically, an upper plastic 17 is set between the reference upper pole 131 and the top cover plate 11, and the reference upper pole 131 is insulated and sealed from the top cover plate 11 through the upper plastic 17. A lower plastic 18 is set between the reference lower pole 132 and the top cover plate 11, and the reference lower pole 132 is insulated and sealed from the top cover plate 11 through the lower plastic 18, so that the reference upper pole 131 and the reference lower pole 132 are directly installed on the outer side and the inner side of the top cover plate 11, and the assembly is convenient and reliable.

[0040] In the above-mentioned square three-electrode battery top cover, an independent reference pole 13 is set on the top cover plate 11, and the reference electrode 33 of the battery cell is directly connected to the reference pole 13. The reference electrode 33 does not need to be led out at the explosion-proof valve 14, so as not to adversely affect the function of the explosion-proof valve 14, so that the function of the explosion-proof valve 14 remains good, and the safety is guaranteed when testing under extreme test conditions such as high temperature and high rate lithium precipitation; and, since the reference electrode 33 is not led out at the explosion-proof valve 14, there is no need to set a lead-out opening at the position where the explosion-proof valve 14 is installed on the top cover plate 11, and no sealant such as epoxy resin glue is required. To seal the lead-out hole, the risk of leakage due to incomplete sealing of the sealant is avoided, and the risk of leakage due to the stability of the sealant being affected under extreme test conditions such as low and high temperatures is avoided; in addition, the reference pole 13 is fixed on the top cover plate 11, so that the reference electrode 33 can be electrically connected to the components outside the battery. The reference electrode 33 does not need to be exposed, and the reference pole 13 does not need additional protection. After the battery is assembled, the reference electrode 33 will not be easily broken or damaged during the subsequent flow of other processes, which is conducive to improving the yield of the finished battery.

[0041] Therefore, in the above-mentioned square three-electrode battery top cover, a reference pole is provided to be connected to the reference electrode to realize the connection setting between the reference electrode and the outside of the battery, which not only avoids the impact on the function of the explosion-proof valve and the risk of battery leakage, but also prevents the connection part of the reference electrode from being led out of the battery, avoiding the reference electrode from being exposed to the outside, so there is no need for additional protective measures, and avoids the risk of reference electrode breakage, which is conducive to ensuring the yield of the finished battery.

[0042] In one possible implementation, Figure 7 and Figure 8 As shown, a fixing hole 1321 and an insulating plug 1322 for cooperating with the fixing hole 1321 are provided on the side of the reference lower electrode 132 facing away from the reference upper electrode 131. The fixing hole 1321 is used for one end of the reference electrode 33 to extend into, and when one end of the reference electrode 33 extends into the fixing hole 1321, the insulating plug 1322 is used to clamp and fix the end of the reference electrode 33, and the material of the insulating plug 1322 can be rubber; a welding area for welding with the reference electrode 33 is formed on the surface of the reference lower electrode 132 facing away from the reference upper electrode 131. One end of the reference electrode 33 extends into the fixing hole 1321 and is electrically connected to the reference lower electrode 132. The insulating plug 1322 is filled in the fixing hole 1321 to press and fix the part of the reference electrode 33 extending into the fixing hole 1321, so that the connection between the reference electrode 33 and the reference lower electrode 132 is simple and reliable. After pressing, the reference electrode 33 can be bent to fit the surface of the reference lower electrode 132 away from the reference upper electrode 131, so that a part of the reference electrode 33 can be welded to the welding area, thereby improving the working efficiency of the connection operation between the reference electrode 33 and the reference lower electrode 132.

[0043] For example, Figure 8 As shown, the fixing hole 1321 is a blind hole, and the axis of the fixing hole 1321 is perpendicular to the top cover plate 11; there are two fixing holes 1321, each fixing hole 1321 is connected to a reference electrode 33, and similarly, two reference connections can be set in the battery.

[0044] In one possible implementation, reference Figure 2 As shown, a positive electrode post 12, a reference electrode post 13, an explosion-proof valve 14, a liquid injection hole 15, and a negative electrode post 16 are arranged in sequence and spaced apart in a first direction parallel to the top cover plate 11. The positive electrode post 12 and the negative electrode post 16 are arranged at both ends of the top cover plate 11, maintaining a certain distance. The reference electrode post 13, the explosion-proof valve 14, and the liquid injection hole 15 are arranged between the positive electrode post 12 and the negative electrode post 16. In addition, the reference electrode post 13 is separated from the positive electrode post 12 by a certain distance to ensure battery safety.

[0045] In a specific implementation, refer to Figure 4 、 Figure 5and Figure 6 As shown, in a direction perpendicular to the top cover plate 11, the orthographic projection of the reference upper pole 131 covers the orthographic projection of the reference lower pole 132. The area of ​​the reference upper pole 131 is set to be larger than the area of ​​the reference pole 13, so that the reference upper pole 131 and the reference lower pole 132 are not completely opposite to each other at the periphery when installed at the reference opening of the top cover plate 11. The inner and outer sides are installed at the periphery of the reference upper pole 131 and the reference lower pole 132 to avoid each other by a certain space, which makes it easy to install and fix them.

[0046] Specifically, refer to Figure 4 、 Figure 5 As shown, in the direction perpendicular to the top cover plate 11 , the orthographic projection of the reference upper pole 131 is a square, and the orthographic projection of the reference lower pole 132 is also a square, which is convenient for processing and installation.

[0047] On the other hand, reference Figure 4 、 Figure 5 As shown, in the direction perpendicular to the top cover plate 11, the area of ​​the orthographic projection of the reference electrode 13 is smaller than the area of ​​the orthographic projection of the positive electrode 12, and smaller than the area of ​​the orthographic projection of the negative electrode 16. Since the current of the reference electrode 33 does not need to be too large and is smaller than that of the positive and negative electrodes, the area of ​​the reference electrode 13 can be set to be smaller than the positive electrode 12 and the negative electrode 16. In addition, the area of ​​the top cover plate 11 is limited. By setting the reference electrode 13 relatively small, the setting space of the top cover plate 11 can be saved, and the distance between the reference electrode 13 and the positive electrode 12 and the negative electrode 16 can be as large as possible to ensure the safety of the battery during use and testing.

[0048] Specifically, for the structural arrangement of the positive electrode column and the negative electrode column, as a possible implementation method, refer to Figure 3 ,like Figure 4 、 Figure 5 and Figure 6As shown, the positive electrode column 12 includes: a positive upper electrode column 121 and a positive lower electrode column 122, the positive upper electrode column 121 is arranged on the outside of the top cover plate 11, and the positive lower electrode column 122 is arranged on the inside of the top cover plate 11, and a positive mounting hole is provided on the top cover plate 11. The positive upper electrode column 121 and the positive lower electrode column 122 are arranged opposite to each other at the positive mounting hole and are installed on the top cover plate 11, and the positive upper electrode column 121 and the positive lower electrode column 122 can be directly contacted and pressed to achieve electrical connection. The positive lower electrode column 122 is used to connect with the positive ear 321; the negative electrode column 16 includes: a negative upper electrode column 161 and a negative lower electrode column 162, the negative upper electrode column 161 is arranged on the outside of the top cover plate 11, and the negative The lower pole post 162 is provided on the inner side of the top cover plate 11. A negative pole mounting hole is provided on the top cover plate 11. The negative pole upper pole post 161 and the negative pole lower pole post 162 are arranged opposite to each other at the negative pole mounting hole and are mounted on the top cover plate 11. The negative pole upper pole post 161 and the negative pole lower pole post 162 can be directly contacted and pressed together to achieve electrical connection. The negative pole lower pole post 162 is used to connect to the negative pole ear 311. Among them, the positive pole upper pole post 121 and the negative pole upper pole post 161 are both insulated and sealed from the top cover plate 11 by the upper plastic 17 and fixed to the top cover plate 11. The positive pole lower pole post 122 and the negative pole lower pole post 162 are both insulated and sealed from the top cover plate 11 by the lower plastic 18 and fixed to the top cover plate 11.

[0049] Preferably, reference Figure 6 As shown, in the direction perpendicular to the top cover plate 11 , the orthographic projection of the positive upper pole 121 covers the orthographic projection of the positive lower pole 122 , and the orthographic projection of the negative upper pole 161 covers the orthographic projection of the negative lower pole 162 . The area of ​​the positive upper pole 121 is set to be larger than the area of ​​the positive lower pole 122, and the area of ​​the negative upper pole 161 is set to be larger than the area of ​​the negative lower pole 162, so that the positive upper pole 121 and the positive lower pole 122 will not be completely opposite to each other at the periphery when installed at the positive pole mounting hole of the top cover plate 11, and the negative upper pole 161 and the negative lower pole 162 will not be completely opposite to each other at the periphery when installed at the negative pole mounting hole of the top cover plate 11. The peripheral positions of the positive upper pole 121 and the positive lower pole 122 installed on the inner and outer sides avoid each other by a certain space, and the peripheral positions of the negative upper pole 161 and the negative lower pole 162 avoid each other by a certain space, so that they are easy to install and fix.

[0050] Exemplary, reference Figure 4 and Figure 5As shown, in the direction perpendicular to the top cover plate 11, the orthographic projection of the positive upper pole 121 and the orthographic projection of the positive lower pole 122 are both square, and the orthographic projection of the negative upper pole 161 and the orthographic projection of the negative lower pole 162 are both square, and the area of ​​the positive upper pole 121 and the negative upper pole 161 can be set to be the same, and the area of ​​the positive lower pole 122 and the negative lower pole 162 can be set to be the same, which facilitates the processing of the positive mounting hole and the negative mounting hole on the top cover plate 11.

[0051] In one possible embodiment, the top cover plate 11 is an aluminum plate, the positive electrode upper post 121 is made of aluminum, the reference electrode upper post 131 is made of copper, the negative electrode upper post 161 is made of a copper-aluminum alloy, the positive electrode lower post 122 is made of aluminum, and the reference electrode lower post 132 and the negative electrode lower post 162 are made of copper. In addition, the upper plastic 17 and the lower plastic 18 can be made of polypropylene.

[0052] Based on the same design concept, such as Figure 1 and Figure 2 As shown, this embodiment also provides a square three-electrode battery, including any square three-electrode battery top cover 1 provided in the above embodiments, as well as a shell 2 and a three-electrode battery cell 3 arranged in the shell 2, wherein the square three-electrode battery top cover 1 is used to close the opening on the top side of the shell 2; wherein the top side of the three-electrode battery cell 3 has a positive electrode ear 321, a negative electrode ear 311 and a connection portion of a reference electrode 33, the positive electrode ear 321 is connected to the positive electrode post 12, the negative electrode ear 311 is connected to the negative electrode post 16, and the connection portion of the reference electrode 33 is connected to the reference lower electrode post 132.

[0053] In a specific embodiment, reference Figure 5 ,like Figure 7 and Figure 8As shown, the side of the reference lower electrode 132 of the square three-electrode battery top cover facing away from the reference upper electrode 131 has a fixing hole 1321 and an insulating plug 1322 for cooperating with the fixing hole 1321, and the surface of the reference lower electrode 132 facing away from the reference upper electrode 131 is formed with a welding area for welding with the reference electrode 33; the free end of the connecting portion of the reference electrode 33 extends into the fixing hole 1321 and is electrically connected to the reference lower electrode 132, and the insulating plug 1322 is filled in the fixing hole 1321 to fix the free end of the connecting portion of the reference electrode 33; and a part of the connecting portion contacts and is welded to the surface of the reference lower electrode 132 on the side away from the reference upper electrode 131. The free end of the connecting portion extends into the fixing hole 1321 and is fixed by inserting the insulating plug 1322. The free end of the connecting portion directly contacts the inner wall of the fixing hole 1321 to achieve electrical connection with the reference lower electrode 132. In order to enhance the connection stability between the connecting portion of the reference electrode 33 and the reference lower electrode 132, the connecting portion can be bent so that part of the connecting portion contacts and is closely attached to the welding area of ​​the reference lower electrode 132, and then welded to the welding area of ​​the reference lower electrode 132 to achieve secondary fixation and electrical connection, thereby enhancing the connection stability between the reference electrode 33 and the reference lower electrode 132. In addition, the free end of the connecting portion of the reference connection is first clamped in the fixing hole 1321, and then the connecting portion is bent so as to contact and weld with the lower surface of the reference lower electrode 132. This is convenient to operate and helps to improve the assembly and connection efficiency.

[0054] In addition, the positive electrode ear and the positive electrode lower pole 122 can be connected by ultrasonic welding, or the positive electrode ear can be connected to the positive electrode lower pole 122 through an adapter plate by laser welding; the negative electrode ear and the negative electrode lower pole 162 can be connected by ultrasonic welding, or the negative electrode ear can be connected to the negative electrode lower pole 162 through an adapter plate by laser welding.

[0055] In the above-mentioned square three-electrode battery, Figure 3 and Figure 9 As shown, the three-electrode cell 3 includes: a negative electrode sheet 31, a positive electrode sheet 32, and a reference electrode 33 that are stacked and isolated from each other, and a separator 34 is provided between adjacent two of the negative electrode sheet 31, the positive electrode sheet 32, and the reference electrode 33; a positive electrode tab 321 is formed on the top side of the positive electrode sheet 32, a negative electrode tab 311 is formed on the top side of the negative electrode sheet 31, and a connecting portion is formed on the top side of the reference electrode 33. Specifically, multiple negative electrode sheets 31 and positive electrode sheets 32 can be provided, and the negative electrode sheets 31 and positive electrode sheets 32 are alternately stacked in sequence, and a separator 34 is provided between adjacent negative electrode sheets 31 and positive electrode sheets 32 to isolate them. The reference electrode 33 can be provided between two adjacent positive electrode sheets 32 and negative electrode sheets 31, and the reference electrode 33 is also isolated from the positive electrode sheet 32 ​​and negative electrode sheet 31 respectively by the separator 34.

[0056] Preferably, the active material coated on the positive electrode plate 32 is lithium iron phosphate, and the active material coated on the negative electrode plate 31 is graphite; the reference electrode 33 is a copper wire, and at least the portion of the copper wire exposed inside the shell 2 is coated with an insulating layer, wherein the copper wire is electrochemically plated with lithium to form the reference electrode 33.

[0057] refer to Figure 3 and Figure 8 As shown, the copper wire adopts enameled copper wire, the enameling of the outer layer of the copper wire forms an insulating layer, the part of the copper wire in contact with the lower pole of the reference electrode 33 is stripped to achieve electrical connection between the copper wire and the reference lower pole 132, and a part of the part where the copper wire is clamped in the stack of the battery cell is stripped, and a part of the part where the copper wire is clamped in the stack of the battery cell near the top side of the battery cell is enameled to ensure good insulation between the copper wire and the electrolyte.

[0058] The outer periphery of the three-electrode battery cell 3 is wrapped with an insulating film, and the housing 2 and the three-electrode battery cell 3 are separated and insulated by the insulating film to prevent the battery cell from short-circuiting. Preferably, the insulating film can be made of polypropylene.

[0059] In addition, the outer side of the shell 2 is covered with an outer film, wherein the shell 2 can be an aluminum shell or a stainless steel shell, and the top cover plate 11 and the shell 2 can be welded by laser welding; the material of the outer film is PET polyethylene terephthalate plastic.

[0060] A specific embodiment of a square three-electrode battery in this solution:

[0061] like Figure 3 As shown, the top cover plate 11 is equipped with a positive electrode post 12, a reference electrode post 13, an explosion-proof valve 14, a liquid injection hole 15, and a negative electrode post 16. After the top cover is completed and the battery cell 3 is manufactured, the positive electrode ear is connected to the positive electrode lower post, the negative electrode ear is connected to the negative electrode lower post, and the copper wire is connected to the reference lower post. After the connection is completed, the three-electrode battery cell 3 is placed in the housing 2, and the top cover plate 11 and the housing 2 are welded and sealed to complete the battery assembly. Then, after baking, liquid injection, aging, formation, sealing, aging, capacity separation, testing, and coating, the battery cell is removed from the production line. When it is removed from the production line, the battery cell capacity is maintained at around 20% to 50% SOC to ensure that there is sufficient lithium source for the negative electrode during subsequent positive and reverse lithium deposition.

[0062] Comparative Example:

[0063] like Figure 1 As shown, Figure 1Figure 2 shows a schematic diagram of the structure of a three-electrode battery in the prior art. The top cover 011 is equipped with a positive electrode post 012, an explosion-proof valve 014, a liquid injection port 015, and a negative electrode post 016. After the top cover and cell 03 are fabricated, the positive tabs are connected to the positive lower post, and the negative tabs are connected to the negative lower post. Copper wire 033 is then routed through explosion-proof valve 014 on the top cover. The three-electrode cell 03 is then placed into the housing 02. The top cover 011 and housing 02 are welded and sealed. After welding, epoxy resin is injected into the explosion-proof valve to seal it, completing the battery assembly. The battery then undergoes a series of assembly steps, including baking, liquid injection, aging, formation, sealing, aging, capacity separation, testing, and film coating. The cell capacity is maintained at approximately 20-50% SOC upon release.

[0064] From the above, it can be seen that compared with the battery in the comparative example, the square three-electrode battery provided in this embodiment has an independent reference pole set on the top cover plate, and the reference electrode of the battery cell is directly connected to the reference pole. The reference electrode does not need to be led out at the explosion-proof valve, so as not to adversely affect the function of the explosion-proof valve, so that the function of the explosion-proof valve remains good, and the safety is guaranteed when testing under extreme test conditions such as high temperature and high rate lithium precipitation; and, since the reference electrode is not led out at the explosion-proof valve, there is no need to set a lead-out opening at the position where the explosion-proof valve is installed on the top cover plate, and no epoxy resin glue is required. The lead-out hole is sealed with sealant, which avoids the risk of leakage due to incomplete sealing of the sealant, and avoids the risk of leakage due to the stability of the sealant under extreme test conditions such as low and high temperatures. In addition, the reference pole is fixed on the top cover plate, which allows the reference electrode to be electrically connected to the components outside the battery. The reference electrode does not need to be exposed, and the reference pole does not need additional protection. After the battery is assembled, the reference electrode will not be easily broken or damaged during the subsequent flow of other processes, which is conducive to improving the yield of the finished battery.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A square three-electrode battery top cover, characterized in that: include: A top cover plate (11), a positive electrode column (12), a reference electrode column (13), an explosion-proof valve (14), a liquid injection hole (15), and a negative electrode column (16), as well as an upper plastic (17) and a lower plastic (18) arranged on the top cover plate (11) and spaced apart; wherein, The reference electrode (13) comprises: a reference upper electrode (131) and a reference lower electrode (132), wherein the reference upper electrode (131) is arranged on the outside of the top cover plate (11), and the reference lower electrode (132) is arranged on the inside of the top cover plate (11), the reference upper electrode (131) and the reference lower electrode (132) are arranged opposite to each other and electrically connected, and the reference lower electrode (132) is used to connect to the reference electrode (33); the reference upper electrode (131) is insulated and sealed with the top cover plate (11) by the upper plastic (17), and the reference lower electrode (132) is insulated and sealed with the top cover plate (11) by the lower plastic (18).

2. The square three-electrode battery top cover according to claim 1, characterized in that: The reference lower pole (132) has a fixing hole (1321) and an insulating plug (1322) for cooperating with the fixing hole (1321) on a side facing away from the reference upper pole (131); the fixing hole (1321) is used for one end of the reference electrode (33) to extend into; and when one end of the reference electrode (33) extends into the fixing hole (1321), the insulating plug (1322) is used to clamp and fix the end of the reference electrode (33); A welding area for welding with the reference electrode (33) is formed on the surface of the reference lower pole (132) facing away from the reference upper pole (131).

3. The square three-electrode battery top cover according to claim 1, characterized in that: In a direction perpendicular to the top cover plate (11), the orthographic projection of the reference upper pole (131) covers the orthographic projection of the reference lower pole (132).

4. The square three-electrode battery top cover according to claim 1, characterized in that: In a direction perpendicular to the top cover plate (11), the area of ​​the orthographic projection of the reference pole (13) is smaller than the area of ​​the orthographic projection of the positive pole (12), and smaller than the area of ​​the orthographic projection of the negative pole (16).

5. The square three-electrode battery top cover according to claim 1, characterized in that: The positive electrode column (12) comprises: a positive electrode upper column (121) and a positive electrode lower column (122), wherein the positive electrode upper column (121) is arranged on the outside of the top cover plate (11), and the positive electrode lower column (122) is arranged on the inside of the top cover plate (11), the positive electrode upper column (121) and the positive electrode lower column (122) are arranged opposite to each other and electrically connected, and the positive electrode lower column (122) is used to connect to the positive electrode ear (321); The negative electrode column (16) comprises: a negative electrode upper column (161) and a negative electrode lower column (162), wherein the negative electrode upper column (161) is arranged on the outside of the top cover plate (11), and the negative electrode lower column (162) is arranged on the inside of the top cover plate (11), the negative electrode upper column (161) and the negative electrode lower column (162) are arranged opposite to each other and electrically connected, and the negative electrode lower column (162) is used to connect to the negative electrode ear (311); The positive upper pole (121) and the negative upper pole (161) are both insulated and sealed from the top cover plate (11) by the upper plastic (17); the positive lower pole (122) and the negative lower pole (162) are both insulated and sealed from the top cover plate (11) by the lower plastic (18).

6. The square three-electrode battery top cover according to claim 5, characterized in that: In a direction perpendicular to the top cover plate (11), the orthographic projection of the positive upper pole (121) covers the orthographic projection of the positive lower pole (122), and the orthographic projection of the negative upper pole (161) covers the orthographic projection of the negative lower pole (162).

7. The square three-electrode battery top cover according to claim 1, characterized in that: The positive electrode column (12), the reference electrode column (13), the explosion-proof valve (14), the injection hole (15), and the negative electrode column (16) are sequentially spaced apart in a first direction parallel to the top cover plate (11).

8. A square three-electrode battery, characterized in that: It comprises a square three-electrode battery top cover (1) as claimed in any one of claims 1 to 7, a shell (2) and a three-electrode battery cell (3) arranged in the shell (2), wherein the square three-electrode battery top cover (1) is used to close the opening on the top side of the shell (2); The top side of the three-electrode battery cell (3) has a positive electrode tab (321), a negative electrode tab (311) and a connection portion of a reference electrode (33); the positive electrode tab (321) is connected to the positive electrode column (12); the negative electrode tab (311) is connected to the negative electrode column (16); and the connection portion of the reference electrode (33) is connected to the reference lower electrode column (132).

9. The square three-electrode battery according to claim 8, characterized in that: The side of the reference lower pole (132) of the square three-electrode battery top cover (1) facing away from the reference upper pole (131) has a fixing hole (1321) and an insulating plug (1322) for cooperating with the fixing hole (1321), and the surface of the reference lower pole (132) facing away from the reference upper pole (131) is formed with a welding area for welding to the reference electrode (33); The free end of the connecting portion of the reference electrode (33) extends into the fixing hole (1321) and is electrically connected to the reference lower electrode (132); the insulating plug (1322) is filled in the fixing hole (1321) to fix the free end of the connecting portion of the reference electrode (33); and a portion of the connecting portion contacts and is welded to a welding area of ​​the reference lower electrode (132).

10. The square three-electrode battery according to claim 8, characterized in that: The three-electrode battery cell (3) comprises: a negative electrode sheet (31), a positive electrode sheet (32) and a reference electrode (33) stacked and isolated from each other, and a diaphragm (34) is provided between two adjacent ones of the negative electrode sheet (31), the positive electrode sheet (32) and the reference electrode (33); the positive electrode ear (321) is formed on the top side of the positive electrode sheet (32), the negative electrode ear (311) is formed on the top side of the negative electrode sheet (31), and the connecting portion is formed on the top side of the reference electrode (33).

11. The square three-electrode battery according to claim 8, characterized in that: The reference electrode (33) is a copper wire, and at least the portion of the copper wire exposed inside the housing (2) is covered with an insulating layer.

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