Secondary battery, method for preparing same, energy storage system, and electrical equipment

Abstract

The present application provides a secondary battery, a preparation method thereof, an energy storage system, and an electrical device, belonging to the technical field of batteries. The secondary battery of the present application includes a battery cell and a top cover, which are covered together; the top cover includes: a top cover plate provided with a pole column; a sealing ring provided with a through hole; the pole column passes through the through hole so that the sealing ring is sleeved on the pole column; a top cover sheet provided with a pole column hole and a wire hole; the pole column sleeved with the sealing ring passes through the pole column hole so that the top cover plate and the top cover sheet are covered together, thereby forming the top cover; along the direction of radially extending outward from the center of the through hole, the sealing ring sequentially includes an inner ring layer, an intermediate layer, and an outer ring layer; the inner ring layer is a rubber layer; the intermediate layer is a thermal phase change layer for regulating the heat generated during the operation of the battery cell; the outer ring layer is a pressure sensing layer, and a wire is provided on the surface of the outer ring layer, and the wire passes through the wire hole to facilitate electrical connection with an external battery management system, and the outer ring layer is used to monitor the internal pressure change of the battery cell. This sealing ring has the effects of thermal management and pressure monitoring.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and in particular, to a secondary battery, a preparation method thereof, an energy storage system, and an electrical device. Background Art

[0002] The cell sealing ring is a sealing element used in the cell assembly process. It is mainly used for sealing between the cell and the outer shell to prevent electrolyte leakage, moisture ingress, and intrusion of other contaminants. This sealing ring is usually made of rubber or other elastic materials and has good elasticity and sealing performance. During the manufacturing and assembly process of the cell, the cell sealing ring plays a crucial role. It can ensure the stability and safety of the cell during long-term use and also helps to extend the service life of the cell.

[0003] Traditional sealing rings mostly use materials such as fluororubber or silica gel and mainly play a sealing role. However, during the long-term charge and discharge operation of the battery, heat is generated, which easily causes the sealing ring to expand or contract due to heat, resulting in fatigue cracking and high-temperature failure of the sealing ring, and triggering the problem of electrolyte leakage. During the operation of the battery, the internal pressure also changes, which may pose a risk of thermal runaway. Moreover, the sealing performance of the sealing ring decreases in a high-temperature environment and it cannot dissipate heat actively. Summary of the Invention

[0004] The main object of the present application is to provide a secondary battery, a preparation method thereof, an energy storage system, and an electrical device to solve the problems in the prior art that the heat during battery operation cannot be regulated in time and the pressure change cannot be warned in time, which may easily lead to a decrease in the sealing performance of the sealing ring in a high-temperature environment of the battery, failure, and affect the safety of the battery.

[0005] To achieve the above object, according to one aspect of the present application, a secondary battery is provided, including a cell, an outer shell, and a top cover. The cell is disposed in the outer shell, and the outer shell and the top cover are closed. The top cover includes:

[0006] A top cover plate, on which a pole post is provided;

[0007] A sealing ring, on which a through hole is provided; the pole post passes through the through hole so that the sealing ring is sleeved on the pole post;

[0008] A top cover sheet, on which a pole post hole and a wire hole are provided; the pole post sleeved with the sealing ring passes through the pole post hole so that the top cover plate and the top cover sheet are closed, thereby forming the top cover;

[0009] Wherein, along the direction of radially extending outward from the center of the through hole, the sealing ring sequentially includes an inner ring layer, an intermediate layer, and an outer ring layer;

[0010] The inner ring layer is a rubber layer;

[0011] The middle layer is a thermal phase change layer, which is used to regulate the heat generated during the operation of the battery cell;

[0012] The outer ring layer is a pressure sensing layer. Conductive wires are provided on the surface of the outer ring layer, and the conductive wires pass through the wire holes to facilitate electrical connection with an external battery management system. The outer ring layer is used to monitor the internal pressure change of the battery cell.

[0013] Furthermore, the wire holes include a first wire hole and a second wire hole; the sealing rings include a first sealing ring and a second sealing ring; the conductive wire of the first sealing ring passes out through the first wire hole to be electrically connected to the battery management system; the conductive wire of the second sealing ring passes out through the second wire hole to be electrically connected to the battery management system.

[0014] Furthermore, the material of the inner ring layer is a first rubber.

[0015] Furthermore, the material of the middle layer is a thermal phase change rubber; the thermal phase change rubber includes a second rubber substrate and a thermal phase change material distributed in the second rubber substrate.

[0016] Furthermore, the material of the middle layer is a third rubber; a first cavity is formed inside the middle layer, and the thermal phase change material is filled in the first cavity.

[0017] Furthermore, the thermal phase change material is distributed in the second rubber substrate in a granular or powdery form.

[0018] Furthermore, the weight percentage content of the thermal phase change material in the thermal phase change rubber is 15% - 25%.

[0019] Furthermore, the phase change temperature of the thermal phase change material is 50°C - 70°C.

[0020] Furthermore, the thermal phase change material is paraffin.

[0021] Furthermore, the first cavity is a first annular cavity; the first annular cavity and the middle layer are coaxially arranged; the radial width of the first annular cavity is 150 - 700 μm, and the axial height is 80 - 120 μm.

[0022] Furthermore, the thermal phase change material fills the first cavity.

[0023] Furthermore, the first rubber, the second rubber substrate, and the third rubber are respectively selected from at least one of fluororubber, silicone rubber, and polydimethylsiloxane.

[0024] Furthermore, the material of the outer ring layer is a fourth rubber; a second cavity is formed inside the outer ring layer, and a first conductive material is filled in the second cavity. The first conductive material is conductive rubber or conductive metal.

[0025] Further, the second cavity is a second annular cavity; the second annular cavity and the outer ring layer are coaxially arranged; the radial width of the second annular cavity is 150 - 600 μm, and the axial height is 80 - 120 μm.

[0026] Further, the second annular cavity is filled with the first conductive material.

[0027] Further, the pressure sensitivity of the first conductive material is 10 - 15 mV / kPa.

[0028] Further, the conductive metal is selected from silver nanowires or liquid metal particles; the liquid metal particles are at least one of gallium indium alloy particles, gallium indium tin alloy particles, and pure gallium particles.

[0029] Further, the conductive metal forms a conductive metal layer in the second cavity; one end of the wire is electrically connected to the conductive metal layer, and the other end of the wire passes through the outer surface of the outer ring layer.

[0030] Further, the wire passes through the axial outer surface of the outer ring layer.

[0031] Further, the wire includes a positive wire and a negative wire.

[0032] Further, the conductive rubber includes a fifth rubber substrate and a second conductive material distributed in the fifth rubber substrate, and the weight percentage of the second conductive material in the conductive rubber is 2% - 10%; the second conductive material includes conductive fillers and conductive polymers; the conductive fillers are selected from at least one of carbon nanotubes, silver nanowires, and liquid metal particles; the conductive polymer is polyaniline and / or polypyrrole.

[0033] Further, the conductive rubber forms a conductive rubber layer in the second cavity, and a positive electrode and a negative electrode are respectively arranged on the surface of the conductive rubber layer; the positive wire and the negative wire are respectively conductively connected to the positive electrode and the negative electrode; the positive electrode and the negative electrode are respectively a conductive silver paste film or a conductive metal sheet.

[0034] Further, the fourth rubber and the fifth rubber substrate are respectively selected from at least one of fluororubber, silicone rubber, and polydimethylsiloxane.

[0035] Further, protruding microvilli are distributed on the surface of the outer ring layer; the length of the microvilli is 20 - 100 μm, the diameter is 5 - 10 μm, and the distance between adjacent two microvilli is 5 - 15 μm.

[0036] Further, the material of the microvilli is a sixth rubber; the sixth rubber is selected from at least one of fluororubber, silicone rubber, and polydimethylsiloxane.

[0037] Further, the radial widths of the inner ring layer, the middle layer, and the outer ring layer are 0.3 - 1 mm, 0.5 - 2 mm, and 0.5 - 1.5 mm respectively.

[0038] Further, the axial height of the sealing ring is 1.1 - 1.2 mm, the inner diameter is 18 - 20 mm, and the outer diameter is 21 - 24 mm.

[0039] Further, the porosities of the inner ring layer, the middle layer, and the outer ring layer increase in sequence.

[0040] Further, the porosity of the outer ring layer is 25% - 30%.

[0041] Further, the porosity of the middle layer is 10% - 20%.

[0042] Further, the porosity of the inner ring layer is greater than 0 and less than or equal to 5%.

[0043] According to the second aspect of the present application, there is provided a method for preparing the above secondary battery, including the assembly process of the top cover:

[0044] Step S1: Pass the pole through the through - hole so that the sealing ring is sleeved on the pole;

[0045] Step S2: Pass the pole sleeved with the sealing ring through the pole hole and pass the wire through the wire hole so that the top cover piece covers the top cover plate;

[0046] Among them, the preparation method of the sealing ring includes the following steps:

[0047] Step S1 - 1: Inject the first mixed glue into the inner - layer cavity of the sealing - ring mold, and after preliminary forming, form the inner ring layer. A through - hole is formed in the inner ring layer; the material of the first mixed glue includes the first rubber;

[0048] Step S1 - 2: Inject the second mixed glue into the middle - layer cavity of the sealing - ring mold, and after preliminary forming, form an attached middle layer on the axial outer surface of the inner ring layer; the second mixed glue includes a thermo - phase - change material;

[0049] Step S1 - 3: Inject the third mixed glue into the outer - layer cavity of the sealing - ring mold, and after preliminary forming, form an attached outer ring layer on the axial outer surface of the middle layer. A second cavity is formed inside the outer ring layer; Inject the first conductive material from the inlet of the outer - layer cavity into the second cavity to form a conductive - material layer; Fix two wires on the surface of the conductive - material layer; Seal the inlet of the outer - layer cavity with the third mixed glue, and leave the wires outside the outer ring layer; Finally, obtain an overall sealing - ring pre - formed body with an inner ring layer, a middle layer, and an outer ring layer formed in sequence in the direction radially extending outward from the center of the through - hole;

[0050] Step S1 - 4: Vulcanize the sealing - ring pre - formed body to obtain the sealing ring.

[0051] Furthermore, the forming methods of the intermediate layer in step S1-2 include a first method and a second method;

[0052] The first method includes: injecting a first type of second mixed glue into the first type of intermediate layer cavity of the sealing ring mold, and after preliminary forming, forming an attached intermediate layer on the axial outer surface of the inner ring layer, and the intermediate layer is a solid structure; the first type of second mixed glue contains a thermal phase change material;

[0053] The second method includes: injecting a second type of second mixed glue into the second type of intermediate layer cavity of the sealing ring mold, and after preliminary forming, forming an attached intermediate layer on the axial outer surface of the inner ring layer, and a first cavity is formed inside the intermediate layer; injecting the thermal phase change material from the inlet of the second type of intermediate layer cavity into the first cavity, and sealing the inlet of the second type of intermediate layer cavity with the second type of second mixed glue; the second type of second mixed glue does not contain a thermal phase change material.

[0054] Furthermore, by weight, the first mixed glue includes the following raw materials: 100 parts of the first rubber raw rubber, 1-2 parts of a vulcanizing agent, 2-3 parts of an accelerator, 20-60 parts of a reinforcing filler, and 2-10 parts of a plasticizer; each raw material is kneaded at a temperature of 170-200 °C to form the first mixed glue.

[0055] Furthermore, by weight, the first type of second mixed glue includes the following raw materials: 100 parts of the second rubber base raw rubber, 1-2 parts of a vulcanizing agent, 2-3 parts of an accelerator, 20-60 parts of a reinforcing filler, 2-10 parts of a plasticizer, and 5-10 parts of a phase change material; each raw material is kneaded at a temperature of 170-200 °C to form the second mixed glue; the phase change material includes paraffin.

[0056] Furthermore, by weight, the second type of second mixed glue includes the following raw materials: 100 parts of the third rubber base raw rubber, 1-2 parts of a vulcanizing agent, 2-3 parts of an accelerator, 20-60 parts of a reinforcing filler, and 2-10 parts of a plasticizer; each raw material is kneaded at a temperature of 170-200 °C to form the second mixed glue.

[0057] Furthermore, by weight, the third mixed glue includes the following raw materials: 100 parts of the fourth rubber raw rubber, 1-2 parts of a vulcanizing agent, 2-3 parts of an accelerator, 20-60 parts of a reinforcing filler, and 2-10 parts of a plasticizer; each raw material is kneaded at a temperature of 170-200 °C to form the third mixed glue.

[0058] Further, the first conductive material is conductive rubber or conductive metal; the conductive metal is selected from silver nanowires and / or liquid metal particles; the liquid metal particles are at least one of gallium indium alloy particles, gallium indium tin alloy particles, and pure gallium particles; the conductive rubber includes a fifth rubber substrate and a second conductive material distributed in the fifth rubber substrate, and the weight percentage of the second conductive material in the conductive rubber is 2% to 10%; the second conductive material includes a conductive filler and a conductive polymer; the conductive filler is selected from at least one of carbon nanotubes, silver nanowires, and liquid metal particles; the conductive polymer is polyaniline and / or polypyrrole.

[0059] Further, between step S1-3 and step S1-4, there is also step S1-34: placing the seal ring preform in a micro-villi mold, injecting a sixth mixed rubber into the micro-villi mold, and after curing and forming, micro-villi are distributed on the axial surface of the outer ring layer of the seal ring preform.

[0060] Further, by weight, the sixth mixed rubber includes the following raw materials: 100 parts of the sixth raw rubber, 1 to 2 parts of a vulcanizing agent, 2 to 3 parts of an accelerator, 5 to 10 parts of a reinforcing filler, and 2 to 10 parts of a plasticizer; each raw material is kneaded at a temperature of 170 to 200 °C to form a first mixed rubber.

[0061] Further, the injection pressures of the first mixed rubber, the second mixed rubber, and the third mixed rubber are each independently 50 to 150 MPa.

[0062] Further, vulcanization includes primary vulcanization and secondary vulcanization; the temperature of primary vulcanization is 170 to 180 °C, and the time of primary vulcanization is 10 to 20 min; the temperature of secondary vulcanization is 180 to 200 °C, and the time of secondary vulcanization is 2 to 4 h.

[0063] According to the third aspect of the present application, an energy storage system is provided, including a plurality of secondary batteries and a battery management system; the secondary battery is the above-mentioned secondary battery or the secondary battery obtained by the preparation method of the above-mentioned secondary battery; the secondary battery and the battery management system are electrically connected through a wire.

[0064] According to the fourth aspect of the present application, an electrical device is provided, including the above-mentioned energy storage system.

[0065] Compared with the prior art, the present application has the following beneficial effects:

[0066] The present application provides a secondary battery, a preparation method thereof, and an energy storage system. By designing a sealing ring with a three-layer structure, each layer has different functions. The inner ring layer serves as a buffer layer to absorb mechanical stress; a thermal phase change material is embedded in the middle layer material, which can absorb the heat generated during the operation of the battery, thereby achieving the effect of reducing the local temperature of the battery; a conductive material is embedded in the outer ring layer material, which can monitor the pressure change during the operation of the battery in real time, thereby achieving the effect of warning the pressure change inside the battery; the sealing ring can prevent thermal runaway and prevent the problem that the sealing performance of the core sealing ring is damaged due to long-term heating or pressure; at the same time, the three-layer materials are mainly made of rubber and cooperate with each other to improve the sealing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The accompanying drawings forming a part of this application are used to provide a further understanding of the application. The schematic embodiments and descriptions thereof of the application are used to explain the application and do not constitute an improper limitation of the application. In the drawings:

[0068] Figure 1 It is a top view structural schematic diagram of the sealing ring prepared in Embodiment 1 of the present application;

[0069] Figure 2 It is a top view structural schematic diagram of the sealing ring provided in Embodiment 2 of the present application;

[0070] Figure 3 It is a top view structural schematic diagram of the sealing ring provided in Embodiment 3 of the present application;

[0071] Figure 4 It is an enlarged schematic diagram of the micro-villus structure protruding from the axial surface of the outer ring layer of the sealing ring provided in Embodiment 4 of the present application;

[0072] Figure 5 It is a schematic diagram of the top cover structure provided in Embodiment 5 of the present application;

[0073] Figure 6 It is a schematic diagram of the secondary battery structure provided in Embodiment 6 of the present application;

[0074] Figure 7 It is a schematic diagram of the radial width and axial height of the sealing ring of the present application embodiment.

[0075] REFERENCE SIGNS:

[0076] 1. Top cover; 11. Top cover plate; 111. Terminal post;

[0077] 12. Sealing ring; 121. Through hole; 122. Inner ring layer; 123. Middle layer; 124. Outer ring layer; 125. Micro-villus; 126. Conducting wire; 127. First cavity; 128. Second cavity; 129. Conductive material layer; 1291. Positive electrode; 1292. Negative electrode; D. Radial width; H. Axial height;

[0078] 13. Top cover sheet; 131. Terminal post hole; 132. Wire hole;

[0079] 2. Battery cell; 3. Secondary battery; 4. Outer shell. Detailed implementation manners

[0080] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0081] As described in the background art, the traditional sealing ring only has a sealing function. Since the sealing ring is prone to heat expansion or contraction under the influence of the battery heat and pressure for a long time, it cannot dissipate heat actively and cannot know the change of the internal pressure of the battery in real time, which easily leads to fatigue cracking of the sealing ring, high-temperature failure, decrease in sealing performance, leakage of liquid, etc. and cannot be adjusted in time.

[0082] To achieve the above object, according to one aspect of the present application, a secondary battery is provided, including a battery cell 2, an outer shell 4 and a top cover 1. The battery cell 2 is arranged inside the outer shell, and the outer shell and the top cover 1 are closed; the top cover 1 includes:

[0083] A top cover plate 11, and a terminal post 111 is provided on the top cover plate 11;

[0084] A sealing ring 12, and a through hole 121 is provided on the sealing ring 12; the terminal post 111 passes through the through hole 121 so that the sealing ring 12 is sleeved on the terminal post 111;

[0085] A top cover sheet 13, and a terminal post hole 131 and a wire hole 132 are provided on the top cover sheet 13; the terminal post 111 sleeved with the sealing ring 12 passes through the terminal post hole 131 so that the top cover plate 11 and the top cover sheet 13 are closed, thereby forming the top cover 1;

[0086] Wherein, along the direction of radially extending outward from the center of the through hole 121, the sealing ring 12 sequentially includes an inner ring layer 122, an intermediate layer 123 and an outer ring layer 124;

[0087] The inner ring layer 122 is a rubber layer;

[0088] The intermediate layer 123 is a thermal phase change layer, which is used to regulate the heat generated during the operation of the battery cell 2;

[0089] The outer ring layer 124 is a pressure sensing layer, a wire 126 is provided on the surface of the outer ring layer, and the wire 126 passes through the wire hole 132 to facilitate electrical connection with an external battery management system. The outer ring layer is used to monitor the change of the internal pressure of the battery cell 2.

[0090] The inner ring layer material of the sealing ring designed in this application is elastic rubber, which is used to absorb mechanical stress; the middle layer contains a thermal phase change material, which is used to absorb the heat generated during the operation of the battery; the outer ring layer contains a pressure sensing material, which is used to sense the change in the resistance of the conductive material in the outer ring layer after the sealing ring is pressed, so as to monitor the change in the internal pressure of the battery; and the three-layer materials are all based on rubber and cooperate with each other to further improve the sealing effect and prevent electrolyte leakage. The sealing ring with three different functional structures designed in this application is, for example, an O-ring, and further, for example, an O-ring with a circular or square through-hole; the secondary battery of this application is, for example, a lithium-ion secondary battery, and further can be a square lithium-ion secondary battery; the process of installing the battery cell body into the outer shell is the prior art, and the process of covering the outer shell and the top cover is the prior art.

[0091] In some embodiments, the wire holes 132 on the top cover sheet 13 include a first wire hole and a second wire hole; the sealing ring 12 includes a first sealing ring and a second sealing ring; the two wires of the first sealing ring (sheathed on the positive electrode post) pass through the first conductive hole for electrical connection with the battery management system; the two wires of the second sealing ring (sheathed on the negative electrode post) pass through the second conductive hole for connection with the battery management system.

[0092] In some embodiments, the material of the inner ring layer 122 is a first rubber, which mainly plays a sealing effect, and the inner wall of the inner ring layer fits tightly with the electrode post.

[0093] In some embodiments, the intermediate layer 123, as a thermal phase change layer, can achieve this function through two structures; the first structure: the material of the intermediate layer 123 is a thermal phase change rubber, and the thermal phase change rubber includes a second rubber substrate and a thermal phase change material distributed in the second rubber substrate. The thermal phase change material is distributed in the second rubber substrate in a granular or powder form, and the weight percentage of the thermal phase change material in the thermal phase change rubber is 15% - 25%; the second structure: the material of the intermediate layer 123 is a third rubber, and a first cavity 127 is formed inside the intermediate layer 123, and the thermal phase change material is filled in the first cavity 127, preferably filled completely; the phase change temperature of the thermal phase change material in the above two structures is > 50°C. By controlling the thermal phase change material PCM above 50°C, it can be regarded as the temperature boundary for the safe operation of the battery. For most lithium-ion batteries, the ideal operating temperature is usually 20 - 60°C. When the battery temperature exceeds 50°C, it may accelerate the chemical reaction rate inside the battery, increase the internal pressure of the battery, and easily trigger thermal runaway, resulting in a decline in battery performance, shortening of life, and safety problems. Setting 50°C as a warning threshold, when the battery temperature approaches or exceeds this temperature, the phase change material starts to absorb heat and melt for temperature reduction treatment to relieve the overheating of the battery; the thermal phase change material will change from a solid state to a liquid state above the phase change temperature, and this process requires absorbing a large amount of heat, thereby reducing the local temperature of the battery. When the battery temperature drops to the phase change temperature, the phase change material will solidify again, which can effectively slow down the temperature fluctuation of the battery and keep the battery operating within a relatively stable temperature range. The phase change temperature of the above thermal phase change material is further 50°C - 70°C; for example, paraffin (melting point 60 - 70°C), EGaIn-paraffin composite, fatty acid (melting point 30 - 50°C), sodium acetate trihydrate (around 60°C) can be selected. The normal operating temperature of the battery is 20 - 60°C, and the melting point of the thermal phase change material PCM within this range (40 - 70°C) can absorb heat and avoid premature melting. In the above cavity structure, preferably, the first cavity 127 is a first annular cavity; the first annular cavity and the intermediate layer are coaxially arranged, and the annular cavity is a through annular cavity, and its size can be designed according to actual needs; for example, the radial width of the first annular cavity (as shown by D in Figure 7 is 150 - 700 μm, and the axial height (as shown by H in Figure 7 is 80 - 120 μm, specifically, the width is 700 μm and the height is 100 μm; the amount of the filled thermal phase change material can also be adjusted according to actual conditions; preferably, the first cavity is basically filled with the thermal phase change material, that is, the volume of the filled thermal phase change material is the same as or close to the volume of the first cavity; or the filling amount of the thermal phase change material is 80% - 100% of the volume of the first cavity, or 90% - 99%, or 90% - 95%.

[0094] In this application, by embedding the thermal phase change material into the rubber material or independently placing the thermal phase change material in the cavity inside the intermediate layer, it has an endothermic melting effect, effectively reducing the local temperature of the battery and alleviating the influence of high temperature on the sealing performance of the sealing ring. For example, solid paraffin melts into liquid paraffin under the heat of the battery, absorbing a large amount of latent heat, and then playing a role in cooling, achieving the purpose of regulating the battery temperature. Controlling the content of the thermal phase change material within the above range is beneficial to improving the endothermic capacity, so as to absorb a large amount of battery heat and more effectively improve the cooling effect, which has a better promoting effect on improving the thermal management effect, and thus better improves the sealing performance of the sealing ring. At the same time, the above content of the thermal phase change material is also more conducive to avoiding the influence of excessive thermal phase change liquid on the local stability of the sealing ring, which will also change the microstructure of the rubber, reduce the continuity and integrity of the rubber matrix, affect the elastic recovery and compression set performance of the material, as well as the mechanical strength and durability, and may cause the sealing ring to be unable to effectively return to its original state during the charge and discharge cycle of the battery, thereby reducing the sealing effect. Therefore, the addition amount of the phase change material such as paraffin should be precisely calculated within the above-mentioned appropriate range, which can ensure the endothermic effect without affecting the sealing performance of the rubber itself.

[0095] In some embodiments, the first rubber, the second rubber substrate, and the third rubber are each selected from at least one of fluororubber, silicone rubber, and polydimethylsiloxane. For example, the fluororubber is selected from at least one of fluororubber 23, fluororubber 26, fluororubber 246, vinylidene fluoride ether rubber (model VITON GLT), and perfluoroether rubber (model KALREZ). The selected fluororubber has excellent chemical stability, high mechanical strength, and good elastic recovery performance, can withstand the expansion and contraction pressure generated during the charge and discharge cycle of the battery, improve the sealing performance and thermal management effect of the battery, extend the service life of the battery, and improve the overall safety.

[0096] In some embodiments, the material of the outer ring layer 124 is the fourth rubber; the fourth rubber can be at least one of fluororubber, silicone rubber, and polydimethylsiloxane. A second cavity 128 is formed inside the outer ring layer 124, and a first conductive material is filled in the second cavity 128. The first conductive material is conductive rubber or conductive metal. Preferably, the second cavity 128 is a second annular cavity; the second annular cavity and the outer ring layer are coaxially arranged; the cavity is a through annular cavity, and the dimensions of the cavity such as depth, width, inner diameter, and the amount of conductive material filled can be designed according to the actual situation; for example, the radial width of the second annular cavity is 150 - 600 μm, and the axial height (such as Figure 7As shown in Fig. H, it is 80 to 120 μm; specifically, the width is 600 μm and the height is 100 μm; preferably, the second cavity is filled with the conductive material, or the filling volume of the conductive material is approximately the same as the volume of the second cavity, or the filling amount of the conductive material is 80% to 100% of the volume of the second cavity, or 90% to 99%, or 90% to 95%; this filling amount can be adjusted according to actual applications.

[0097] In some embodiments, the pressure sensitivity of the first conductive material is 10 to 15 mV / kPa. Controlling the sensitivity within the above range can avoid an increase in signal noise or an unclear pressure response, which is beneficial for the monitoring and warning of the battery pressure.

[0098] In some embodiments, the conductive metal is selected from silver nanowires or liquid metal particles; the liquid metal particles are at least one of gallium indium alloy particles, gallium indium tin alloy particles, and pure gallium particles. The selected conductive materials have good electrical conductivity, can be sensitive to tiny pressure changes, can effectively form a conductive network to achieve the pressure sensing function, and the above conductive materials are easy to process and operate.

[0099] In some embodiments, the conductive metal forms a conductive material layer 129 in the second cavity 128; one end of the wire 126 is electrically connected to the conductive material layer 129, and the other end of the wire 126 passes through the outer surface of the outer ring layer 124. Adopting this structural design can achieve the pressure sensing function inside the outer ring layer, and the rubber shell of the outer ring layer has good insulation; in this structure, preferably, the wire 126 passes through the axial outer surface of the outer ring layer 124, that is, two wires are led out from the surface in the thickness direction of the outer ring layer. The positive wire sequentially passes through the first wire hole and the second wire hole to be electrically connected to the positive access module of the external battery management system, and the negative wire sequentially passes through the first negative wire hole and the second negative wire hole to be electrically connected to the negative access module of the external battery management system to form the positive and negative circuits.

[0100] In some embodiments, the conductive rubber includes a fifth rubber substrate and a second conductive material distributed in the fifth rubber substrate, and the weight percentage of the second conductive material in the conductive rubber is 2% to 10%; for example, any value of 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any range of values ​​between two. The second conductive material includes a conductive filler and a conductive polymer; the conductive filler is selected from at least one of carbon nanotubes, silver nanowires, and liquid metal particles; and the conductive polymer is polyaniline and / or polypyrrole. The conductive rubber forms a conductive material layer 129 in the second cavity 128, and a positive electrode and a negative electrode are respectively arranged on the surface of the conductive material layer 129; further, a positive electrode and a negative electrode can be respectively arranged on the side close to the inner ring and the side close to the outer ring of the same layer surface of the conductive material layer 129; the positive electrode wire and the negative electrode wire are respectively corresponding to the positive electrode 1291 and the negative electrode 1292 and are conductively connected; the positive electrode and the negative electrode are respectively conductive silver paste films or conductive metal sheets, and the electrode material only needs to be conductive material, and further select easy-to-process materials, for example, the conductive silver paste is sprayed on the preset electrode position on the surface of the conductive rubber layer by spraying to form a conductive electrode, and other conductive and easy-to-operate materials can also be selected.

[0101] The present application embeds conductive materials in rubber or fills conductive materials in the cavity, and can change the resistance of the conductive materials according to the internal pressure of the battery, and then convert this change into a detectable electrical signal, thereby achieving the purpose of real-time monitoring of the internal pressure change of the battery. For example, when conductive carbon particles are subjected to internal pressure of the battery, the conductive network in the conductive rubber will be deformed, resulting in a change in the resistance of the conductive path, and this change can be an increase in resistance or a decrease in resistance; the change in resistance has a certain relationship with the magnitude of the pressure, so the internal pressure of the battery can be indirectly measured by detecting the change in resistance; the change in resistance can be detected by electrodes connected to the conductive material, and the electrodes are connected to the external battery management system BMS; by measuring the current change or voltage change through the conductive material in the circuit, the resistance change can be converted into an electrical signal; the BMS will continuously detect the pressure change of the sealing ring, and will issue a warning signal when the pressure exceeds the safe range, helping the battery management system to take timely measures, such as cutting off the power supply, starting the cooling system, etc., to prevent safety problems caused by excessive internal pressure of the battery. When the amount of conductive material added is within the above-mentioned appropriate range, a sufficient conductive network can be formed to promote the conductivity and sensitivity of the sealing ring, which is beneficial to accurately detect the internal pressure of the battery, and is beneficial to maintaining the good mechanical strength, durability, softness and elasticity of the sealing ring, so that the sealing ring is not easily damaged when under pressure.

[0102] In some embodiments, protruding microvilli 125 are distributed on the surface of the outer ring layer 124; the length of the microvilli 125 is 20 - 100 μm, the diameter is 5 - 10 μm, and the distance between two adjacent microvilli 125 is 5 - 15 μm. The material of the microvilli 125 is the sixth rubber; the sixth rubber is selected from at least one of fluororubber, silicone rubber, and polydimethylsiloxane. For example, setting protruding microvilli on the surface in the thickness direction of the outer ring layer can further improve the contact sealing effect of the sealing ring; further, imitating gecko foot hairs and arranging them in an array can further enhance the contact sealing performance.

[0103] In some embodiments, the radial width of the outer ring layer is 0.5 - 1.5 mm to ensure stability and avoid affecting flexibility and overall dimensions due to excessive thickness; the radial width of the middle layer is 0.5 - 2 mm to ensure the microchannel and PCM functions and avoid occupying too much space; the radial width of the inner ring layer is 0.3 - 1 mm to fit with the terminal post, and the thickness should not be too large; among them, the radial width and axial height of the first cavity of the middle layer and the second cavity of the outer ring layer can be adaptively adjusted according to the size of the sealing ring of the present application.

[0104] In some embodiments, the porosity of the inner ring layer 122, the middle layer 123, and the outer ring layer 124 increases in sequence. The porosity of the inner ring layer 122 is greater than 0 and less than or equal to 5%; the porosity of the middle layer 123 is 10% - 20%; the porosity of the outer ring layer 124 is 25% - 30%; the above porosities can be adjusted by the content of fillers in each layer. The inner ring layer needs high sealing performance, so the pores are as small as possible; the middle layer needs to provide certain elasticity or buffering force, so it has certain pores and is evenly distributed; the outer layer needs to be wear-resistant and corrosion-resistant, and the pores can be slightly larger to increase the surface area of the material and improve wear resistance.

[0105] In some embodiments, the axial height (i.e., the thickness of the sealing ring) of the sealing ring 12 is 1.1 - 1.2 mm, the inner diameter is 18 - 20 mm, and the outer diameter is 21 - 24 mm. For example, the inner diameter is 19 mm and the outer diameter is 23 mm. The size of this sealing ring can be adjusted according to the actual application field; for example, for a mobile phone square battery, the size of the sealing ring is relatively small; for an automotive battery, the size of the sealing ring is relatively large; therefore, the size of this sealing ring can be adjusted according to the actual application.

[0106] According to the second aspect of the present application, a method for preparing the above secondary battery is provided, including the assembly process of the top cover 1;

[0107] Step S1: Pass the terminal post 111 through the through hole 121 so that the sealing ring 12 is sleeved on the terminal post 111;

[0108] Step S2: Pass the terminal post 111 sleeved with the sealing ring 12 through the terminal post hole 131 and pass the wire 126 through the wire hole 132 so that the top cover sheet 13 covers the top cover plate 11;

[0109] Among them, the preparation method of the sealing ring 12 includes the following steps:

[0110] Step S1-1: Inject the first mixed glue into the inner cavity of the sealing ring mold, and after preliminary forming, form an inner ring layer 122, and a through hole 121 is formed in the inner ring layer 122; the material of the first mixed glue includes the first rubber;

[0111] Step S1-2: Inject the second mixed glue into the middle cavity of the sealing ring mold, and after preliminary forming, form an attached middle layer 123 on the axial outer surface of the inner ring layer 122; the second mixed glue includes a thermal phase change material;

[0112] Step S1-3: Inject the third mixed glue into the outer cavity of the sealing ring mold, and after preliminary forming, form an attached outer ring layer 124 on the axial outer surface of the middle layer 123, and a second cavity 128 is formed inside the outer ring layer 124; Inject the first conductive material into the second cavity 128 from the inlet of the outer cavity to form a conductive material layer; Fix two wires on the surface of the conductive material layer; Seal the inlet of the outer cavity with the third mixed glue, and keep the wires outside the outer ring layer; Seal the inlet of the outer cavity with the third mixed glue; Finally, obtain an overall sealing ring preform body with an inner ring layer 122, a middle layer 123, and an outer ring layer 124 formed in sequence in the direction radially extending outward from the center of the through hole 121;

[0113] Step S1-4: Vulcanize the sealing ring preform to obtain the sealing ring 12.

[0114] The type, structure, etc. of the sealing ring mold used in the above preparation method of the present application are all prior arts, and the injection method and vulcanization method can be selected from the prior arts as long as a three-layer structure rubber sealing ring can be formed.

[0115] In some embodiments, the forming method of the middle layer in Step S1-2 includes a first method and a second method;

[0116] The first method includes: Inject the first type of second mixed glue into the first type of middle cavity of the sealing ring mold, and after preliminary forming, form an attached middle layer on the axial outer surface of the inner ring layer, and the middle layer is a solid structure; The first type of second mixed glue contains a thermal phase change material;

[0117] The second method includes: injecting the second second mixed glue into the second intermediate layer cavity of the sealing ring mold, forming an attached intermediate layer on the axial outer surface of the inner ring layer after preliminary forming, and a first cavity 127 is formed inside the intermediate layer; injecting the thermo-phase change material into the first cavity from the inlet of the second intermediate layer cavity, and sealing the inlet of the second intermediate layer cavity with the second second mixed glue; the second second mixed glue does not contain thermo-phase change material.

[0118] In some embodiments, by weight, the first mixed glue includes the following raw materials: 100 parts of the first raw rubber, 1 - 2 parts of vulcanizing agent, 2 - 3 parts of accelerator, 20 - 60 parts of reinforcing filler, 2 - 10 parts of plasticizer; each raw material is kneaded at a temperature of 170 - 200 °C to form the first mixed glue. The first rubber prepared with this formula has good sealing effect, good mechanical strength, and the porosity of the inner ring layer 122 can be adjusted by the content of the filler, and the type and content of the filler affect the pore structure and sealing performance of the rubber.

[0119] In some embodiments, by weight, the first second mixed glue includes the following raw materials: 100 parts of the second raw rubber substrate, 1 - 2 parts of vulcanizing agent, 2 - 3 parts of accelerator, 20 - 60 parts of reinforcing filler, 2 - 10 parts of plasticizer, 5 - 10 parts of phase change material; each raw material is kneaded at a temperature of 170 - 200 °C to form the second mixed glue; the phase change material includes paraffin wax.

[0120] In some embodiments, by weight, the second second mixed glue includes the following raw materials: 100 parts of the third raw rubber substrate, 1 - 2 parts of vulcanizing agent, 2 - 3 parts of accelerator, 20 - 60 parts of reinforcing filler, 2 - 10 parts of plasticizer; each raw material is kneaded at a temperature of 170 - 200 °C to form the second mixed glue. The third rubber prepared with this formula has good sealing effect, good mechanical strength, and the porosity of the intermediate layer 123 can be adjusted by the content of the filler, and the type and content of the filler affect the pore structure and sealing performance of the rubber.

[0121] In some embodiments, by weight, the third mixed glue includes the following raw materials: 100 parts of the fourth raw rubber, 1 - 2 parts of vulcanizing agent, 2 - 3 parts of accelerator, 20 - 60 parts of reinforcing filler, 2 - 10 parts of plasticizer; each raw material is kneaded at a temperature of 170 - 200 °C to form the third mixed glue. The fourth rubber prepared with this formula has good sealing effect, good mechanical strength, and the porosity of the outer ring layer 124 can be adjusted by the content of the filler, and the type and content of the filler affect the pore structure and sealing performance of the rubber.

[0122] In some embodiments, the first conductive material is conductive rubber or conductive metal; the conductive metal is selected from silver nanowires and / or liquid metal particles; the liquid metal particles are at least one of gallium indium alloy particles, gallium indium tin alloy particles, and pure gallium particles; the conductive rubber includes a fifth rubber substrate and a second conductive material distributed in the fifth rubber substrate, and the weight percentage of the second conductive material in the conductive rubber is 2% to 10%; the second conductive material includes a conductive filler and a conductive polymer; the conductive filler is selected from at least one of carbon nanotubes, silver nanowires, and liquid metal particles; the conductive polymer is polyaniline and / or polypyrrole.

[0123] In some embodiments, between step S1-3 and step S1-4, there is also step S1-34: placing the seal ring preform in a micro-villi mold, injecting a sixth mixed rubber into the micro-villi mold, and after curing and forming, micro-villi 125 are distributed on the axial surface of the outer ring layer of the seal ring preform. The structure of the above micro-villi mold is a prior art and can be selected from the prior art.

[0124] In some embodiments, by weight, the sixth mixed rubber includes the following raw materials: 100 parts of the sixth raw rubber, 1 to 2 parts of a vulcanizing agent, 2 to 3 parts of an accelerator, 5 to 10 parts of a reinforcing filler, and 2 to 10 parts of a plasticizer; each raw material is kneaded at a temperature of 170 to 200 °C to form a first mixed rubber.

[0125] In some embodiments, the above raw rubbers are each independently at least one of raw rubbers such as fluororubber, silicone rubber, and polydimethylsiloxane. For example, the fluororubber is selected from at least one of fluororubber 23, fluororubber 26, fluororubber 246, vinylidene fluoride ether rubber (model VITON GLT), and perfluoroether rubber (model KALREZ). The selected fluororubber has excellent chemical stability, relatively high mechanical strength, and good elastic recovery performance, can withstand the expansion and contraction pressures generated during the charge and discharge cycles of the battery, can improve the sealing performance and thermal management effect of the battery, extend the service life of the battery, and improve the overall safety.

[0126] In some embodiments, the vulcanizing agents in the first raw rubber, the second raw rubber, the third rubber substrate raw rubber, and the fourth rubber substrate raw rubber are each independently dicumyl peroxide; the accelerators are each independently triallyl isocyanurate, DTBP, DCP, TAC, TBAC, etc.; the reinforcing fillers are each independently carbon black N330 or carbon black N550; the plasticizers are each independently PFPE, fluorinated oil, PPG, PEG-ME, etc. The above various additives can be selected from the prior art; by selecting the above preferred materials, the performance of each layer of rubber can be improved as a whole.

[0127] In some embodiments, the injection pressures of the first rubber mixing, the second rubber mixing, and the third rubber mixing are each independently 50 to 150 MPa. Vulcanization includes primary vulcanization and secondary vulcanization; the temperature of primary vulcanization is 170 to 180 °C, and the time is 10 to 20 min; this can cause the rubber to undergo a cross-linking reaction to obtain basic physical and mechanical properties; the temperature of secondary vulcanization is 180 to 200 °C, for example, 190 °C, and the time is 2 to 4 h; secondary vulcanization can further improve the cross-linking structure of the rubber and improve the heat resistance, aging resistance, etc. of the sealing ring. By optimizing process parameters such as injection pressure and vulcanization time during the second vulcanization, the comprehensive performance of each layer of rubber can be further improved.

[0128] According to the third aspect of the present application, an energy storage system is provided, including a plurality of secondary batteries 3 and a battery management system; the secondary battery 3 is the above-mentioned secondary battery or a secondary battery obtained by the preparation method of the above-mentioned secondary battery; the secondary battery 3 and the battery management system are electrically connected through a wire 126.

[0129] According to the fourth aspect of the present application, an electrical device is provided, including the above-mentioned energy storage system or including the above-mentioned secondary battery. Such devices include, for example, mobile phones, household appliances, electric vehicles, power grids, etc.

[0130] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0131] All raw materials used in the embodiments of the present application are existing technologies and are all commercially available.

[0132] Example 1

[0133] Preparation of an O-ring seal:

[0134] Step S1: Weigh and mix the ingredients according to the respective ratios.

[0135] a. Inner ring layer material: 100 parts of fluororubber 23, 55 parts of reinforcing filler carbon black N330, 5 parts of plasticizer fluorinated oil, 2 parts of vulcanizing agent DCP, and 3 parts of accelerator TAIC; Put the raw rubber of fluororubber 23 into an open mill and plasticize it for 5 minutes to soften it, then add the reinforcing filler carbon black N330 and the plasticizer fluorinated oil in sequence, mix for 15 minutes, and then add the vulcanizing agent DCP (dicumyl peroxide) and the accelerator TAIC (triallyl isocyanurate), control the roller temperature at 70 °C, and mix for 10 minutes to obtain the first rubber mixture.

[0136] b. Intermediate layer material: 100 parts of fluororubber 23, 35 parts of reinforcing filler carbon black N330, 5 parts of plasticizer fluorinated oil, 2 parts of vulcanizing agent DCP, 3 parts of accelerator TAIC, 10 parts of paraffin wax; Put the raw rubber of fluororubber 23 into an open mill, plasticize for 5 minutes to soften it, then add the reinforcing filler carbon black N330, plasticizer fluorinated oil, and paraffin wax in sequence, mix for 15 minutes, and then add the vulcanizing agent DCP (dicumyl peroxide) and accelerator TAIC (triallyl isocyanurate), control the roller temperature at 70 °C, and mix for 10 minutes to obtain the second mixed rubber;

[0137] c. Outer ring layer material: 100 parts of fluororubber 23, 25 parts of reinforcing filler carbon black N330, 5 parts of plasticizer fluorinated oil, 2 parts of vulcanizing agent DCP, 3 parts of accelerator TAIC; Put the raw rubber of fluororubber 23 into an open mill, plasticize for 5 minutes to soften it, then add the reinforcing filler carbon black N330 and plasticizer fluoride in sequence, mix for 15 minutes, and then add the vulcanizing agent DCP (dicumyl peroxide) and accelerator TAIC (triallyl isocyanurate), control the roller temperature at 70 °C, and mix for 10 minutes to obtain the third mixed rubber;

[0138] Step S2: Use injection molding to form; Inject the first mixed rubber into the inner layer cavity of the sealing ring mold at a pressure of 100 MPa, and after preliminary forming, form the inner ring layer 122; Then inject the second mixed rubber into the intermediate layer cavity of the sealing ring mold at a pressure of 100 MPa, and after preliminary forming, form an attached intermediate layer 123 on the axial outer surface of the inner ring layer 122 (the inner ring layer and the intermediate layer form an integral body, and the intermediate layer is a solid structure); Finally, inject the third mixed rubber into the outer layer cavity of the sealing ring mold (a ring-shaped hollow structure can be formed in the mold outer layer cavity structure) at a pressure of 100 MPa, and after preliminary forming, form an attached outer ring layer 124 on the axial outer surface of the intermediate layer 123. A through-ring-shaped second cavity 128 (radial width 600 μm, axial height 100 μm) is formed inside the outer ring layer 124; First, make a suspension of gallium-indium alloy liquid particles (the metal particle material basically fills the second cavity 128), and then inject it into the second cavity 128 from the inlet of the outer layer cavity. After drying, a conductive metal layer 129 is formed in the second cavity. Then, fix two wires on the surfaces of the conductive metal layer 129 near the inner ring side and the outer ring side inside the outer ring layer. The wire diameter is about 1 mm; Use the third mixed rubber to seal the inlet of the outer layer cavity, and make the two wires pass through the rubber shell of the outer ring layer and remain outside the outer ring layer; Finally, obtain an integral sealing ring preform that is formed with an inner ring layer 122, an intermediate layer 123, and an outer ring layer 124 (with a second cavity 128 inside) in sequence in the direction radially extending outward from the center of the through-hole 121;

[0139] Step S3: The sealing ring preform is vulcanized twice; the temperature for the first vulcanization is 175 °C and the time is 15 min; the temperature for the second vulcanization is 190 °C and the time is 3 h, and finally the vulcanized sealing ring is obtained; the structure of the sealing ring is three-dimensionally scanned by X-ray, the internal structure is reconstructed, and the porosity of each layer is quantitatively analyzed. The porosities of the inner ring layer, the middle layer, and the outer ring layer are 4.2%, 18.6%, and 27.4% respectively; the structure of the sealing ring is as Figure 1 shown.

[0140] Example 2

[0141] The difference between Example 2 and Example 1 is that an annular cavity structure is provided in the middle layer cavity of the sealing ring mold;

[0142] Step S3: The second mixed rubber formula for the middle layer: 100 parts of fluororubber 23, 25 parts of reinforcing filler carbon black N330, 5 parts of plasticizer fluorinated oil, 2 parts of vulcanizing agent DCP, and 3 parts of accelerator TAIC; the second mixed rubber is injected into the middle layer cavity of the sealing ring mold (the mold can form an annular cavity structure) at a pressure of 100 MPa, and the attached middle layer 123 is formed on the axial outer surface of the inner ring layer 122 after preliminary forming; a through annular first cavity 127 (radial width 600 μm, axial height 100 μm) is formed inside the middle layer by using the mold; liquid paraffin is injected into the first cavity 127 from the inlet of the middle layer cavity (the paraffin basically fills the first cavity, leaving a space for the liquid to change into a solid state), and the inlet of the cavity body is sealed with the second mixed rubber to obtain the middle layer; finally, an overall sealing ring preform is obtained in which an inner ring layer 122, a middle layer 123 (with a first cavity 127 inside), and an outer ring layer 124 (with a second cavity 128 inside) are sequentially formed in the direction radially extending outward from the center of the through hole 121; the structure of the sealing ring is as Figure 2 shown.

[0143] Example 3

[0144] The difference between Example 3 and Example 1 is that the first conductive material in the outer ring layer is replaced with conductive rubber; the formula of the conductive rubber: 100 parts of fluororubber 23, 30 parts of reinforcing filler carbon black N330, 5 parts of plasticizer fluorinated oil, 2 parts of vulcanizing agent DCP, 3 parts of accelerator TAIC, 10 parts of conductive filler silver nanowires, and the conductive rubber is obtained after mixing; the conductive rubber is injected from the inlet of the outer layer cavity into the second cavity 128 to form a conductive material layer 129 in the cavity, and conductive silver paste is sprayed on the surface of the conductive material layer 129 close to the inner ring and the surface close to the outer ring respectively, and a positive electrode 1291 and a negative electrode 1292 are formed after curing; then two wires 126 are fixed on these two conductive electrodes respectively, and the wire diameter is about 1 mm; the third mixed glue is used to seal the inlet of the outer layer cavity, and the two wires pass through the rubber shell of the outer layer and remain outside the outer ring layer; the partial sectional view structure of the outer ring layer of the sealing ring is as Figure 3 shown.

[0145] Example 4

[0146] The difference between Example 4 and Example 1 is that between step S2 and step S3, there is also step S23: the sealing ring preform is placed in the micro-villous mold, and the sixth mixed glue is injected into the micro-villous mold. After curing and molding, micro-villi 125 are distributed on the axial surface of the outer ring layer of the sealing ring preform, and the partial enlarged view is as Figure 4 shown; the length of the micro-villi is 50 μm, the diameter is 10 μm, and the distance between adjacent two micro-villi is 15 μm; the formula of the sixth mixed glue is: 100 parts of fluororubber, 2 parts of vulcanizing agent DCP, 3 parts of accelerator TAIC, 10 parts of reinforcing filler carbon black N330, 10 parts of plasticizer fluorinated oil.

[0147] Example 5

[0148] A top cover 1 includes: a top cover plate 11, and the top cover plate 11 is provided with a terminal post 111;

[0149] A sealing ring 12, and the sealing ring is any one of the sealing rings prepared in Examples 1 to 4 respectively;

[0150] A top cover sheet 13, the top cover sheet 13 is provided with a terminal post hole 131 and a wire hole 132, and the wire hole 132 includes a first wire hole and a second wire hole; the terminal post 111 sleeved with the sealing ring 12 passes through the terminal post hole 131 to make the top cover plate 11 and the top cover sheet 13 cover each other, thereby forming the top cover 1;

[0151] Specifically, the structure of the sealing ring 12 includes: along the direction of radially extending outward from the center of the through hole 121, the sealing ring 12 successively includes an inner ring layer 122, an intermediate layer 123, and an outer ring layer 124; the inner ring layer 122 is a fluororubber layer; the intermediate layer 123 is a thermal phase change layer, which is used to regulate the heat generated during the operation of the battery cell 2; the outer ring layer 124 is a pressure sensing layer, and a wire 126 is provided on the axial surface of the outer ring layer. The wire 126 passes through the wire hole 132 to facilitate electrical connection with an external battery management system. The outer ring layer is used to monitor the internal pressure change of the battery cell 2;

[0152] Among them, the sealing ring 12 includes a first sealing ring and a second sealing ring; the wire of the first sealing ring passes through the first wire hole, and the wire of the second sealing ring passes through the second wire hole; the top cover disassembly structure is as Figure 5 shown.

[0153] Embodiment 6

[0154] A secondary battery 3 includes a battery cell 2, a housing 4, and a top cover 1. The battery cell 2 is disposed inside the housing 4, and the housing 4 and the top cover 1 are fixedly closed; the top cover 1 is respectively 4 kinds of top covers assembled in Embodiment 14; the schematic diagram of the secondary battery structure is as Figure 6 shown.

[0155] Embodiment 7

[0156] An energy storage system includes the secondary battery 3 of Embodiment 6 and a battery management system BMS; the secondary battery 3 is connected to the battery management system BMS through a wire 126.

[0157] The beneficial effects of the present application are as follows: By designing a sealing ring with a three-layer structure, each layer has different functions. The inner ring layer can absorb mechanical stress as a buffer layer; the intermediate layer material is embedded with a thermal phase change material, which can absorb the heat of the battery and melt to reduce the local temperature of the battery; the outer ring layer material is embedded with a conductive material, which can change the resistance under pressure and transmit signals, and can monitor the internal pressure change of the battery in real time, so as to warn of the internal pressure of the battery and prevent thermal runaway, and can prevent the problem that the sealing performance of the battery cell sealing ring is damaged due to long-term heating or pressure; at the same time, all three layers of materials are based on rubber and cooperate with each other to improve the sealing effect.

[0158] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those described herein.

[0159] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A secondary battery, comprising a battery cell, a housing and a top cover, wherein the battery cell is arranged in the housing, and the housing and the top cover are covered; characterized in that: The top cover comprises: A top cover plate, wherein the top cover plate is provided with a pole; A sealing ring, wherein the sealing ring is provided with a through hole; the pole passes through the through hole so that the sealing ring is sleeved on the pole; A top cover sheet, wherein the top cover sheet is provided with a pole hole and a wire hole; the pole sleeved with the sealing ring passes through the pole hole so that the top cover plate and the top cover sheet are covered, thereby forming the top cover; Wherein, along the direction extending radially outward from the center of the through hole, the sealing ring comprises an inner ring layer, a middle layer and an outer ring layer in sequence; The inner ring layer is a rubber layer, and its material is the first rubber; The intermediate layer is a thermal phase change layer, which is used to adjust the heat generated during the operation of the battery core; the material of the intermediate layer is thermal phase change rubber; the thermal phase change rubber includes a second rubber substrate and a thermal phase change material distributed in the second rubber substrate, or the material of the intermediate layer is a third rubber, a first cavity is opened inside the intermediate layer, and the first cavity is a first annular cavity; the first annular cavity and the intermediate layer are coaxially arranged; the thermal phase change material is filled in the first cavity; the phase change temperature of the thermal phase change material is 50°C~70°C; The outer ring layer is a pressure sensing layer, and a wire is arranged on the surface of the outer ring layer; the material of the outer ring layer is a fourth rubber; a second cavity is provided inside the outer ring layer, and the second cavity is a second annular cavity; the second annular cavity and the outer ring layer are coaxially arranged; the second cavity is filled with a first conductive material, and the filling amount of the first conductive material is 80% to 100% of the volume of the second annular cavity; the first conductive material is conductive rubber or conductive metal; the wire includes a positive wire and a negative wire; The conductive metal forms a conductive metal layer in the second cavity, one end of the conductive wire is electrically connected to the conductive metal layer, and the other end of the conductive wire passes through the outer surface of the outer ring layer; The conductive rubber forms a conductive rubber layer in the second cavity, a positive electrode and a negative electrode are respectively arranged on the surface of the conductive rubber layer, and the positive electrode and the negative electrode are respectively a conductive silver paste film or a conductive metal sheet; the positive electrode wire and the negative electrode wire are respectively corresponding to and conductively connected to the positive electrode and the negative electrode; The wire passes through the wire hole to facilitate electrical connection with an external battery management system, and the outer ring layer is used to monitor the internal pressure change of the battery cell; The porosity of the inner annular layer, the middle layer and the outer annular layer increases in sequence.

2. The secondary battery according to claim 1, characterized in that: The wire holes include a first wire hole and a second wire hole; the sealing ring includes a first sealing ring and a second sealing ring; the wire of the first sealing ring passes through the first wire hole to be electrically connected to the battery management system; the wire of the second sealing ring passes through the second wire hole to be electrically connected to the battery management system.

3. The secondary battery according to claim 1, characterized in that: The thermal phase change material is distributed in the second rubber substrate in the form of particles or powder; and / or the weight percentage of the thermal phase change material in the thermal phase change rubber is 15% to 25%; And / or, the thermal phase change material is paraffin; And / or, the thermal phase change material fills the first cavity; And / or, the radial width of the first annular cavity is 150-700 μm, and the axial height is 80-120 μm; And / or, the first rubber, the second rubber base material and the third rubber are respectively selected from at least one of fluororubber, silicone rubber and polydimethylsiloxane.

4. The secondary battery according to any one of claims 1 to 3, characterized in that: The second annular cavity has a radial width of 150-600 μm and an axial height of 80-120 μm; And / or, the pressure sensitivity of the first conductive material is 10-15 mV / kPa; And / or, the first conductive material completely fills the second annular cavity; and / or, the conductive metal is selected from silver nanowires or liquid metal particles; The liquid metal particles are at least one of gallium-indium alloy particles, gallium-indium-tin alloy particles and pure gallium particles; And / or, the conductive wire passes through the axial outer surface of the outer annular layer.

5. The secondary battery according to any one of claims 1 to 3, characterized in that: The conductive rubber comprises a fifth rubber substrate and a second conductive material distributed in the fifth rubber substrate, and the weight percentage of the second conductive material in the conductive rubber is 2% to 10%; the second conductive material comprises a conductive filler and a conductive polymer; the conductive filler is selected from at least one of carbon nanotubes, silver nanowires and liquid metal particles; the conductive polymer is polyaniline and / or polypyrrole; And / or, the fourth rubber substrate and the fifth rubber substrate are respectively selected from at least one of fluororubber, silicone rubber and polydimethylsiloxane.

6. The secondary battery according to any one of claims 1 to 3, characterized in that: The surface of the outer annular layer is distributed with protruding microvilli; the length of the microvilli is 20-100 μm, the diameter is 5-10 μm, and the distance between two adjacent microvilli is 5-15 μm; And / or, the material of the micro-villi is a sixth rubber; the sixth rubber is selected from at least one of fluororubber, silicone rubber and polydimethylsiloxane.

7. The secondary battery according to any one of claims 1 to 3, characterized in that: The radial widths of the inner ring layer, the middle layer and the outer ring layer are 0.3-1 mm, 0.5-2 mm and 0.5-1.5 mm respectively; And / or, the sealing ring has an axial height of 1.1-1.2 mm, an inner diameter of 18-20 mm, and an outer diameter of 21-24 mm.

8. The secondary battery according to any one of claims 1 to 3, characterized in that: The porosity of the inner annular layer is greater than 0 and less than or equal to 5%; And / or, the porosity of the intermediate layer is 10% to 20%; And / or, the porosity of the outer ring layer is 25%~30%.

9. A method for preparing a secondary battery according to any one of claims 1 to 8, comprising an assembly process of a top cover; characterized in that: The assembly process includes: Step S1: passing the pole through the through hole so that the sealing ring is sleeved on the pole; Step S2: passing the pole with the sealing ring through the pole hole and passing the wire through the wire hole so that the top cover sheet covers the top cover plate; The method for preparing the sealing ring comprises the following steps: Step S1-1: injecting a first mixed rubber into the inner cavity of the sealing ring mold, and forming the inner ring layer after preliminary molding, wherein the inner ring layer is molded with the through hole; the material of the first mixed rubber includes a first rubber; Step S1-2: injecting a second mixed rubber into the middle layer cavity of the sealing ring mold, and forming the middle layer attached to the axial outer surface of the inner ring layer after preliminary molding; the second mixed rubber includes a thermal phase change material; Step S1-3: injecting the third mixed glue into the outer cavity of the sealing ring mold, forming the outer ring layer attached to the axial outer surface of the intermediate layer after preliminary molding, and forming a second cavity inside the outer ring layer; injecting the first conductive material into the second cavity from the entrance of the outer cavity to form a conductive material layer; fixing two wires on the surface of the conductive material layer; using the third mixed glue to seal the entrance of the outer cavity; finally, obtaining an integral sealing ring preform extending radially outward from the center of the through hole, with the inner ring layer, the intermediate layer and the outer ring layer sequentially molded; Step S1-4: vulcanizing the sealing ring preform to obtain the sealing ring.

10. The method for preparing a secondary battery according to claim 9, characterized in that: The forming method of the intermediate layer in step S1-2 includes a first method and a second method; The first method includes: injecting the first and second mixed rubbers into the first intermediate layer cavity of the sealing ring mold, and forming the intermediate layer attached to the axial outer surface of the inner ring layer after preliminary molding, wherein the intermediate layer is a solid structure; the first and second mixed rubbers contain the thermal phase change material; The second method includes: injecting the second second mixed rubber into the second intermediate layer cavity of the sealing ring mold, forming an attached intermediate layer on the axial outer surface of the inner ring layer after preliminary molding, and forming a first cavity inside the intermediate layer; injecting the thermal phase change material from the entrance of the second intermediate layer cavity into the first cavity, and sealing the entrance of the second intermediate layer cavity with the second second mixed rubber; the second second mixed rubber does not contain the thermal phase change material; And / or, the first mixed rubber includes the following raw materials in parts by weight: 100 parts of first rubber raw rubber, 1-2 parts of vulcanizing agent, 2-3 parts of accelerator, 20-60 parts of reinforcing filler, and 2-10 parts of plasticizer; the raw materials are mixed at a temperature of 170-200° C. to form the first mixed rubber; And / or, in parts by weight, the first second mixed rubber comprises the following raw materials: 100 parts of second rubber base rubber, 1-2 parts of vulcanizer, 2-3 parts of accelerator, 20-60 parts of reinforcing filler, 2-10 parts of plasticizer, and 5-10 parts of phase change material; the raw materials are mixed at a temperature of 170-200° C. to form the second mixed rubber; the phase change material comprises paraffin wax; And / or, the second second mixed rubber comprises the following raw materials, in parts by weight: 100 parts of the third rubber base raw rubber, 1-2 parts of the vulcanizing agent, 2-3 parts of the accelerator, 20-60 parts of the reinforcing filler, and 2-10 parts of the plasticizer; the raw materials are mixed at a temperature of 170-200° C. to form the second mixed rubber; And / or, the third mixed rubber comprises the following raw materials in parts by weight: 100 parts of the fourth rubber raw rubber, 1-2 parts of the vulcanizing agent, 2-3 parts of the accelerator, 20-60 parts of the reinforcing filler, and 2-10 parts of the plasticizer; the raw materials are mixed at a temperature of 170-200° C. to form the third mixed rubber; And / or, the first conductive material is conductive rubber or conductive metal; the conductive metal is selected from silver nanowires and / or liquid metal particles; the liquid metal particles are at least one of gallium-indium alloy particles, gallium-indium-tin alloy particles, and pure gallium particles; the conductive rubber includes a fifth rubber substrate and a second conductive material distributed in the fifth rubber substrate, and the weight percentage of the second conductive material in the conductive rubber is 2% to 10%; the second conductive material includes a conductive filler and a conductive polymer; the conductive filler is selected from at least one of carbon nanotubes, silver nanowires, and liquid metal particles; the conductive polymer is polyaniline and / or polypyrrole; And / or, in parts by weight, the conductive rubber comprises the following raw materials: 100 parts of the second rubber base material raw rubber, 1-2 parts of the vulcanizing agent, 2-3 parts of the accelerator, 20-60 parts of the reinforcing filler, 2-10 parts of the plasticizer, and 5-10 parts of the conductive filler; And / or, step S1-34 is further included between step S1-3 and step S1-4: placing the sealing ring preform in a micro-fleece mold, injecting a sixth mixed rubber into the micro-fleece mold, and distributing micro-fleece on the axial surface of the outer ring layer of the sealing ring preform after curing and molding; And / or, in parts by weight, the sixth mixed rubber comprises the following raw materials: 100 parts of the sixth rubber raw rubber, 1-2 parts of the vulcanizing agent, 2-3 parts of the accelerator, 5-10 parts of the reinforcing filler, and 2-10 parts of the plasticizer; the raw materials are mixed at a temperature of 170-200° C. to form the first mixed rubber; And / or, the injection pressures of the first mixed glue, the second mixed glue and the third mixed glue are independently 50-150 MPa; And / or, the vulcanization includes primary vulcanization and secondary vulcanization; the temperature of the primary vulcanization is 170-180° C., and the time of the primary vulcanization is 10-20 minutes; the temperature of the secondary vulcanization is 180-200° C., and the time of the secondary vulcanization is 2-4 hours.

11. An energy storage system, comprising a plurality of secondary batteries and a battery management system; characterized in that: The secondary battery is the secondary battery according to any one of claims 1 to 8 or the secondary battery obtained by the method for preparing the secondary battery according to claim 9 or 10; the secondary battery and the battery management system are electrically connected via the wire.

12. An electrical equipment, comprising an energy storage system, characterized in that: The energy storage system is the energy storage system according to claim 11.

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