Secondary battery and preparation method thereof, energy storage system and electric equipment

Abstract

The invention provides a secondary battery and a preparation method thereof, an energy storage system and electric equipment, and belongs to the technical field of batteries. The secondary battery comprises a battery cell and a top cover which are covered with each other, the top cover comprises: a top cover plate provided with a pole; the sealing ring is provided with a through hole; the pole penetrates through the through hole, so that the sealing ring is arranged on the pole in a sleeving manner; the top cover plate is provided with a pole hole and a lead hole; the pole sleeved with the sealing ring penetrates through the pole hole to enable the top cover plate and the top cover plate to be covered, so that a top cover is formed; the sealing ring sequentially comprises an inner ring layer, a middle layer and an outer ring layer in the direction that the center of the through hole extends outwards in the radial direction. The inner ring layer is a rubber layer; the middle layer is a thermal phase change layer and is used for adjusting heat generated in the operation process of the battery cell; the outer ring layer is a pressure sensing layer, a wire is arranged on the surface of the outer ring layer, the wire penetrates through the wire hole so as to be electrically connected with an external battery management system, and the outer ring layer is used for monitoring the internal pressure change of the battery cell. The sealing ring has the effects of heat management and pressure monitoring.

Description

Technical Field

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

[0002] The battery cell seal is a sealing element used in the battery cell assembly process. It is mainly used to seal between the battery cell and the shell to prevent electrolyte leakage, water ingress and the intrusion of other contaminants. This seal is usually made of rubber or other elastic materials and has good elasticity and sealing properties. In the manufacturing and assembly process of the battery cell, the battery cell seal plays a vital role. It can ensure the stability and safety of the battery cell during long-term use, and also help to extend the service life of the battery cell.

[0003] Traditional sealing rings are mostly made of materials such as fluororubber or silicone, which mainly play a sealing role. However, the heat generated by the battery during long-term charging and discharging operation can easily cause the sealing ring to expand or contract due to heat, which can lead to fatigue cracking of the sealing ring and failure at high temperature, causing electrolyte leakage problems. During the operation of the battery, its internal pressure will also change, which may cause the risk of thermal runaway, and the sealing performance of the sealing ring will decrease in high temperature environment, and it cannot actively dissipate heat. Summary of the invention

[0004] The main purpose of the present application is to provide a secondary battery and its preparation method, energy storage system and electrical equipment, so as to solve the problems in the prior art that the heat during the battery operation process cannot be timely regulated and the pressure change cannot be timely warned, which easily leads to the sealing performance of the sealing ring being reduced and failing in the high temperature environment of the battery, and affects the safety of the battery.

[0005] In order to achieve the above object, according to one aspect of the present application, a secondary battery is provided, including 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; the top cover includes:

[0006] A top cover plate, wherein the top cover plate is provided with a pole;

[0007] 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;

[0008] A top cover sheet is provided with a pole hole and a wire hole; a pole with a sealing ring is passed through the pole hole to cover the top cover plate and the top cover sheet, thereby forming a top cover;

[0009] Wherein, in the direction extending radially outward from the center of the through hole, the sealing ring includes an inner ring layer, a middle layer and an outer ring layer in sequence;

[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. A wire is provided on the surface of the outer ring layer. The wire passes through the wire hole to facilitate electrical connection with the external battery management system. The outer ring layer is used to monitor the internal pressure changes of the battery cell.

[0013] Furthermore, the wire hole includes 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.

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

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

[0016] Furthermore, the material of the middle layer is a third rubber; a first cavity is opened 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 of the thermal phase change material in the thermal phase change rubber is 15% to 25%.

[0019] Furthermore, the phase change temperature of the thermal phase change material is 50°C to 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 intermediate 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 base material 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 provided inside the outer ring layer, and a first conductive material is filled in the second cavity, and the first conductive material is conductive rubber or conductive metal.

[0025] Furthermore, 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 150~600μm, and the axial height is 80~120μm.

[0026] Furthermore, the first conductive material completely fills the second annular cavity.

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

[0028] Furthermore, 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] Furthermore, 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.

[0030] Furthermore, the wire passes through the axial outer surface of the outer annular layer.

[0031] Furthermore, the wires include a positive wire and a negative wire.

[0032] Furthermore, 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; and the conductive polymer is polyaniline and / or polypyrrole.

[0033] Furthermore, 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 electrode wire and the negative electrode wire are respectively corresponding to and conductively connected with the positive electrode and the negative electrode; the positive electrode and the negative electrode are respectively conductive silver paste films or conductive metal sheets.

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

[0035] Furthermore, the surface of the outer annular layer is distributed with protruding microvilli; the length of the microvilli is 20~100μm, the diameter is 5~10μm, and the distance between two adjacent microvilli is 5~15μm.

[0036] Furthermore, the material of the micro-hair is a sixth rubber; the sixth rubber is selected from at least one of fluororubber, silicone rubber and polydimethylsiloxane.

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

[0038] Furthermore, 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.

[0039] Furthermore, the porosity of the inner annular layer, the middle layer and the outer annular layer increases in sequence.

[0040] Furthermore, the porosity of the outer ring layer is 25% to 30%.

[0041] Furthermore, the porosity of the middle layer is 10% to 20%.

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

[0043] According to a second aspect of the present application, a method for preparing the secondary battery is provided, including an assembly process of a 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 with the sealing ring through the pole hole and pass the wire through the wire hole so that the top cover sheet covers the top cover plate;

[0046] The preparation method of the sealing ring comprises the following steps:

[0047] Step S1-1: injecting a first mixed rubber into the inner cavity of the sealing ring mold, and forming an inner ring layer after preliminary molding, wherein the inner ring layer is molded with a through hole; the material of the first mixed rubber includes a first rubber;

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

[0049] Step S1-3: injecting the third mixed glue into the outer cavity of the sealing ring mold, forming an attached outer ring layer on the axial outer surface of the middle 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, and retaining the wires outside the outer ring layer; finally, obtaining an integral sealing ring preform with an inner ring layer, a middle layer and an outer ring layer sequentially molded in a radial direction extending from the center of the through hole;

[0050] Step S1-4: vulcanizing the sealing ring preform to obtain a sealing ring.

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

[0052] The first method includes: injecting the first and second mixed rubbers into the first intermediate layer cavity of the sealing ring mold, and forming an attached intermediate layer on 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 a thermal phase change material;

[0053] 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 using the second second mixed rubber to seal the entrance of the second intermediate layer cavity; the second second mixed rubber does not contain thermal phase change material.

[0054] Furthermore, the first mixed rubber includes the following raw materials, measured 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.

[0055] Furthermore, the first second mixed rubber includes the following raw materials, measured in parts by weight: 100 parts of second rubber base raw rubber, 1 to 2 parts of vulcanizer, 2 to 3 parts of accelerator, 20 to 60 parts of reinforcing filler, 2 to 10 parts of plasticizer, and 5 to 10 parts of phase change material; the raw materials are mixed at a temperature of 170 to 200° C. to form the second mixed rubber; the phase change material includes paraffin.

[0056] Furthermore, the second second mixed rubber includes the following raw materials, measured in parts by weight: 100 parts of the third rubber base raw rubber, 1 to 2 parts of the vulcanizer, 2 to 3 parts of the accelerator, 20 to 60 parts of the reinforcing filler, and 2 to 10 parts of the plasticizer; the raw materials are mixed at a temperature of 170 to 200° C. to form the second mixed rubber.

[0057] Furthermore, the third mixed rubber includes the following raw materials, measured in parts by weight: 100 parts of the fourth rubber raw rubber, 1-2 parts of the vulcanizer, 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.

[0058] Furthermore, 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] Furthermore, step S1-34 is also included between step S1-3 and step S1-4: placing the sealing ring preform in a micro-fleece mold, injecting the sixth mixed rubber into the micro-fleece mold, and after curing and molding, the axial surface of the outer ring layer of the sealing ring preform is distributed with micro-fleece.

[0060] Furthermore, the sixth mixed rubber includes the following raw materials, measured in parts by weight: 100 parts of sixth rubber raw rubber, 1-2 parts of vulcanizing agent, 2-3 parts of accelerator, 5-10 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.

[0061] Furthermore, the injection pressures of the first, second and third mixtures are independently 50-150 MPa.

[0062] Furthermore, 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.

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

[0064] According to a fourth aspect of the present application, there is provided an electrical device comprising the above energy storage system.

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

[0066] The present application provides a secondary battery and a preparation method and an energy storage system thereof. 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; 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 changes during the operation of the battery in real time, thereby achieving the effect of warning the internal pressure changes of the battery; the sealing ring can prevent thermal runaway and prevent the sealing performance of the battery core sealing ring from being damaged by long-term heat or pressure; at the same time, the three layers of material are mainly rubber, which cooperate with each other to improve the sealing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

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

[0069] Figure 2 A schematic diagram of the top view of the sealing ring provided in Example 2 of the present application;

[0070] Figure 3 A schematic diagram of the top view of the sealing ring provided in Example 3 of the present application;

[0071] Figure 4 This is an enlarged schematic diagram of the micro-villi structure protruding on the axial surface of the outer ring layer of the sealing ring provided in Example 4 of the present application;

[0072] Figure 5 A schematic diagram of the top cover structure provided in Example 5 of the present application;

[0073] Figure 6 A schematic diagram of the secondary battery structure provided in Example 6 of the present application;

[0074] Figure 7 Schematic diagram of the radial width and axial height of the sealing ring of the embodiment of the present application.

[0075] Reference numerals:

[0076] 1. Top cover; 11. Top cover plate; 111. Pole;

[0077] 12, sealing ring; 121, through hole; 122, inner ring layer; 123, middle layer; 124, outer ring layer; 125, microvilli; 126, 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; 131. Pole hole; 132. Wire hole;

[0079] 2. Battery cell; 3. Secondary battery; 4. Casing. DETAILED DESCRIPTION

[0080] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0081] As described in the background technology, the traditional sealing ring only has a sealing function. Since the sealing ring is easily expanded or contracted due to the heat and pressure of the battery for a long time, it cannot actively dissipate heat and cannot understand the changes in the internal pressure of the battery in real time. It is easy to cause fatigue cracking of the sealing ring, high-temperature failure, reduced sealing, and leakage, which cannot be regulated in time.

[0082] In order to achieve the above-mentioned object, according to one aspect of the present application, a secondary battery is provided, including a battery cell 2, a housing 4 and a top cover 1, wherein the battery cell 2 is arranged in the housing, and the housing and the top cover 1 are covered; the top cover 1 includes:

[0083] A top cover plate 11, the top cover plate 11 is provided with a pole 111;

[0084] The sealing ring 12 is provided with a through hole 121; the pole 111 passes through the through hole 121 so that the sealing ring 12 is sleeved on the pole 111;

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

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

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

[0088] The middle layer 123 is a thermal phase change layer, which is used to adjust 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 disposed on the surface of the outer ring layer. The wire 126 passes through a wire hole 132 to facilitate electrical connection with an external battery management system. The outer ring layer is used to monitor the internal pressure changes 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 thermal phase change material, which is used to absorb the heat generated during the operation of the battery; the outer ring layer contains pressure sensing material, which is used to sense the change in resistance of the conductive material of the outer ring layer after the sealing ring is compressed, and then monitor the pressure change inside the battery; and the three layers of material are mainly rubber, which cooperate with each other to further improve the sealing effect and prevent electrolyte leakage. The sealing ring with three layers of different functional structures designed in this application is such as an O-ring, and further such as an O-ring with a circular or square through hole; the secondary battery of this application is such as a lithium battery secondary battery, and further can be a square lithium battery secondary battery; the above-mentioned installation of the battery body into the shell is a prior art, and the process of covering the shell and the top cover is a prior art.

[0091] In some embodiments, the wire hole 132 on the top cover sheet 13 includes 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 (sleeved on the positive electrode column) pass through the first conductive hole to facilitate electrical connection with the battery management system; the two wires of the second sealing ring (sleeved on the negative electrode column) pass through the second conductive hole to facilitate connection with the battery management system.

[0092] In some embodiments, the material of the inner ring layer 122 is the first rubber, which mainly plays a sealing role, and the inner wall of the inner ring layer and the pole are tightly fitted.

[0093] In some embodiments, the middle layer 123 can be used as a thermal phase change layer to achieve the function through two structures; the first structure: the material of the middle layer 123 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, the thermal phase change material is distributed in the second rubber substrate in 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 middle layer 123 is a third rubber, the interior of the middle layer 123 opens a first cavity 127, and the first cavity 127 is filled with a thermal phase change material, preferably filled; the phase change temperature of the thermal phase change material in the above two structures is greater than 50°C, and by controlling the thermal phase change material PCM above 50°C, it can be regarded as the temperature for safe operation of the battery. The ideal operating temperature for most lithium-ion batteries is usually 20~60℃. When the battery temperature exceeds 50℃, the internal chemical reaction rate of the battery may be accelerated, the internal pressure of the battery may be increased, and thermal runaway may be easily caused, resulting in decreased battery performance, shortened life, and safety issues. 50℃ is set as a warning threshold. When the battery temperature approaches or exceeds this temperature, the phase change material begins to absorb heat and melt, and the temperature is reduced to alleviate the overheating of the battery. The thermal phase change material will change from solid to liquid above the phase change temperature. This process requires the absorption of 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. This can effectively slow down the temperature fluctuation of the battery and keep the battery working within a relatively stable temperature range. The phase change temperature of the above-mentioned 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 (about 60°C) can be selected. The normal operating temperature of the battery is 20~60°C. The melting point of the thermal phase change material PCM in this range (40~70°C) can absorb heat to avoid premature melting. In the above-mentioned cavity structure, the first cavity 127 is preferably a first annular cavity; the first annular cavity and the middle 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 (such as Figure 7 D in the middle) is 150~700μm, and the axial height (as shown in Figure 7 The width of the first cavity is 80-120 μm, specifically 700 μm in width and 100 μm in height. The amount of the thermal phase change material filled can also be adjusted according to actual conditions. Preferably, the first cavity is substantially filled with the thermal phase change material, that is, the volume of the filled thermal phase change material is the same or nearly the same as the volume of the first cavity. Alternatively, the amount of the thermal phase change material filled is 80%-100%, or 90%-99%, or 90%-95% of the volume of the first cavity.

[0094] The present application embeds the thermal phase change material into the rubber material or independently places the thermal phase change material in the cavity inside the middle layer, which has the effect of absorbing heat and melting, effectively reduces the local temperature of the battery, and alleviates the influence of high temperature on the sealing performance of the sealing ring; for example, solid paraffin is melted into liquid paraffin by the heat of the battery, absorbs a large amount of latent heat, and then plays a role in cooling, thereby achieving the purpose of regulating the battery temperature; the content of the thermal phase change material is controlled within the above range, which is conducive to improving the heat absorption capacity, so as to absorb a large amount of battery heat, more effectively improve the cooling effect, and have a better promoting effect on the improvement of thermal management effect, thereby better improving 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, and will also change the microstructure of the rubber, reduce the continuity and integrity of the rubber matrix, affect the elastic recovery and compression permanent deformation performance of the material, as well as the mechanical strength and durability, which may cause the sealing ring to be unable to effectively restore to its original state during the battery charge and discharge cycle, thereby reducing the sealing effect; therefore, the addition amount of phase change material such as paraffin should be carefully calculated within the above more suitable range, which can ensure the heat absorption 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 respectively 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, parafluoroether 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 by the battery during the charge and discharge cycle, can improve the sealing and thermal management effect of the battery, extend the battery life, and improve the overall safety.

[0096] In some embodiments, the material of the outer ring layer 124 is a fourth rubber; the fourth rubber can be at least one of fluororubber, silicone rubber and polydimethylsiloxane. A second cavity 128 is opened inside the outer ring layer 124, and a first conductive material is filled in the second cavity 128, and 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, amount of conductive material filled, etc. can be designed according to actual conditions; for example, the radial width of the second annular cavity is 150~600μm, and the axial height (such as Figure 7The conductive material is preferably filled with the second cavity, or the filling volume of the conductive material is substantially the same as the volume of the second cavity, or the filling amount of the conductive material is 80% to 100%, or 90% to 99%, or 90% to 95% of the volume of the second cavity; the filling amount can be adjusted according to actual applications.

[0097] In some embodiments, the pressure sensitivity of the first conductive material is 10-15 mV / kPa. Controlling the sensitivity within the above range can avoid increasing signal noise or unclear pressure response, which is beneficial to the monitoring and early warning of 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 material has good conductivity, can respond sensitively to small pressure changes, can effectively form a conductive network, realize the pressure sensing function, and the conductive material is 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. This structural design can realize the pressure sensing function inside the outer ring layer, and the rubber shell of the outer ring layer has good insulation; in this structure, it is preferred to pass the wire 126 through the axial outer surface of the outer ring layer 124, that is, two wires are drawn out from the surface in the thickness direction of the outer ring layer, the positive wire passes through the first wire hole and the second wire hole in turn to be electrically connected to the positive access module of the external battery management system, and the negative wire passes through the first negative wire hole and the second negative wire hole in turn to be electrically connected to the negative access module of the external battery management system, so as to realize 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, the surface of the outer ring layer 124 is distributed with protruding microvilli 125; 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, protruding microvilli are arranged on the surface in the thickness direction of the outer ring layer, which can further improve the contact sealing effect of the sealing ring; further, the microvilli are arranged in an array to imitate the hair of the gecko's feet, which can further improve the contact sealing performance.

[0103] In some embodiments, the radial width of the outer ring layer is 0.5~1.5mm to ensure stability and avoid being too thick to affect flexibility and overall size; the radial width of the middle layer is 0.5~2mm to ensure the microchannel and PCM functions and avoid occupying too much space; the radial width of the inner ring layer is 0.3~1mm to fit the pole and the thickness should not be too large; wherein 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 adjusted according to the size of the sealing ring in this 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% to 20%; the porosity of the outer ring layer 124 is 25% to 30%; the above porosity can be adjusted by the filler content of each layer. The pores of the inner ring layer need to be highly sealed, so the pores are as small as possible; the middle layer needs to provide a certain elasticity or buffering force, so it has a certain amount of 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 of the sealing ring 12 (i.e., the thickness 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, for example, the inner diameter is 19 mm and the outer diameter is 23 mm. The size of the sealing ring can be related to the actual application field; for example, when used in a square battery of a mobile phone, the size of the sealing ring is smaller; when used in a car battery, the size of the sealing ring is more adaptable; therefore, the size of the sealing ring can be adjusted according to the actual application.

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

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

[0108] Step S2: Pass the pole 111 with the sealing ring 12 through the pole 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] The preparation method of the sealing ring 12 comprises the following steps:

[0110] Step S1-1: injecting a first mixed rubber into the inner cavity of the sealing ring mold, and forming an inner ring layer 122 after preliminary molding, wherein the inner ring layer 122 is molded with a through hole 121; the material of the first mixed rubber includes a first rubber;

[0111] Step S1-2: injecting a second mixed rubber into the middle layer cavity of the sealing ring mold, and forming an attached middle layer 123 on the axial outer surface of the inner ring layer 122 after preliminary molding; the second mixed rubber 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 molding, form an attached outer ring layer 124 on the axial outer surface of the intermediate layer 123, and the inner part of the outer ring layer 124 is molded with a second cavity 128; inject the first conductive material into the second cavity 128 from the entrance of the outer cavity to form a conductive material layer; fix two wires on the surface of the conductive material layer; use the third mixed glue to seal the entrance of the outer cavity, and keep the wires outside the outer ring layer; use the third mixed glue to seal the entrance of the outer cavity; finally, obtain an integral sealing ring preform extending radially outward from the center of the through hole 121, in which the inner ring layer 122, the intermediate layer 123 and the outer ring layer 124 are sequentially molded;

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

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

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

[0116] The first method includes: injecting the first and second mixed rubbers into the first intermediate layer cavity of the sealing ring mold, and forming an attached intermediate layer on 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 a thermal phase change material;

[0117] 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 127 inside the intermediate layer; injecting the thermal phase change material from the entrance of the second intermediate layer cavity into the first cavity, and using the second second mixed rubber to seal the entrance of the second intermediate layer cavity; the second second mixed rubber does not contain thermal phase change material.

[0118] In some embodiments, the first rubber mixture 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 rubber mixture. The first rubber prepared by the 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. The type and content of the filler affect the pore structure and sealing performance of the rubber.

[0119] In some embodiments, the first second mixed rubber includes the following raw materials, measured in parts by weight: 100 parts of second rubber base raw 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 includes paraffin.

[0120] In some embodiments, the second second mixed rubber includes the following raw materials in parts by weight: 100 parts of the third rubber base rubber, 1-2 parts of the vulcanizer, 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. The third rubber prepared by this formula has a good sealing effect, good mechanical strength, and the porosity of the middle layer 123 can be adjusted by the content of the filler. The type and content of the filler affect the pore structure and sealing performance of the rubber.

[0121] In some embodiments, the third mixed rubber includes the following raw materials in parts by weight: 100 parts of the fourth rubber raw rubber, 1-2 parts of the vulcanizer, 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. The fourth rubber prepared by the formula has a good sealing effect, good mechanical strength, and the porosity of the outer ring layer 124 can be adjusted by the content of the filler. 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, step S1-34 is further included between step S1-3 and step S1-4: placing the sealing ring preform in a micro-villi mold, injecting the sixth mixed glue into the micro-villi mold, and after curing and molding, the axial surface of the outer ring layer of the sealing ring preform is distributed with micro-villi 125. The structure of the above-mentioned micro-villi mold is prior art and can be selected from prior art.

[0124] In some embodiments, the sixth mixed rubber includes the following raw materials, measured in parts by weight: 100 parts of sixth rubber raw rubber, 1-2 parts of vulcanizer, 2-3 parts of accelerator, 5-10 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.

[0125] In some embodiments, the above-mentioned raw rubber is 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, parafluoroether rubber (model VITON GLT) and perfluoroether rubber (model KALREZ). The above-mentioned fluororubber has excellent chemical stability, high mechanical strength and good elastic recovery performance, can withstand the expansion and contraction pressure generated by the battery during the charge and discharge cycle, can improve the sealing and thermal management effect of the battery, extend the battery life, and improve the overall safety.

[0126] In some embodiments, the vulcanizing agent in the first rubber raw rubber, the second rubber raw rubber, the third rubber base rubber and the fourth rubber base rubber is independently dicumyl peroxide; the accelerator is independently triallyl isocyanurate, DTBP, DCP, TAC, TBAC, etc.; the reinforcing filler is independently carbon black N330 or carbon black N550; the plasticizer is independently PFPE, fluorinated oil, PPG, PEG-ME, etc. The above 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 pressure of the first mixed rubber, the second mixed rubber, and the third mixed rubber is independently 50-150 MPa. Vulcanization includes primary vulcanization and secondary vulcanization; the temperature of primary vulcanization is 170-180°C and the time is 10-20 minutes; the rubber can undergo cross-linking reaction to obtain basic physical and mechanical properties; the temperature of secondary vulcanization is 180-200°C, for example, 190°C, and the time is 2-4 hours; secondary vulcanization can further improve the cross-linking structure of the rubber and improve the heat resistance and aging resistance of the sealing ring. The second vulcanization can further improve the comprehensive performance of each layer of rubber by optimizing the injection pressure, vulcanization time and other processes.

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

[0129] According to a fourth aspect of the present application, there is provided an electrical device, including the above energy storage system or the above secondary battery, such as a mobile phone, household appliance, electric vehicle, power grid, etc.

[0130] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0131] All raw materials used in the examples of this application are prior art and can be purchased commercially.

[0132] Example 1

[0133] Prepare O-ring:

[0134] Step S1: batching and mixing the ingredients according to the proportion of each group;

[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 vulcanizer DCP, and 3 parts of accelerator TAIC; put the raw fluororubber 23 into the open mill equipment, plasticize 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, then add the vulcanizer DCP (diisopropylbenzene peroxide) and the accelerator TAIC (triallyl isocyanurate), control the roller temperature at 70°C, mix for 10 minutes, and obtain the first mixed rubber;

[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, and 10 parts of paraffin wax; put the raw fluororubber 23 into the open mixing 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, then add the vulcanizing agent DCP (diisopropylbenzene peroxide) and accelerator TAIC (triallyl isocyanurate), control the roller temperature at 70°C, mix for 10 minutes, and 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, and 3 parts of accelerator TAIC; put the raw fluororubber 23 into the open mill equipment, plasticize for 5 minutes to soften it, then add the reinforcing filler carbon black N330 and the plasticizer fluorinated in sequence, mix for 15 minutes, then add the vulcanizing agent DCP (diisopropylbenzene peroxide) and the accelerator TAIC (triallyl isocyanurate), control the roller temperature at 70°C, mix for 10 minutes, and obtain the third mixed rubber;

[0138] Step S2: molding by injection molding; injecting the first mixed glue into the inner cavity of the sealing ring mold at a pressure of 100 MPa, and forming an inner ring layer 122 after preliminary molding; injecting the second mixed glue into the middle cavity of the sealing ring mold at a pressure of 100 MPa, and forming an attached middle layer 123 on the axial outer surface of the inner ring layer 122 after preliminary molding (the inner ring layer and the middle layer form a whole, and the middle layer is a solid structure); finally, injecting the third mixed glue into the outer cavity of the sealing ring mold at a pressure of 100 MPa (a ring-shaped hollow structure can be formed in the outer cavity structure of the mold), and forming an attached outer ring layer 124 on the axial outer surface of the middle layer 123 after preliminary molding, and forming a through-annular second cavity 128 (radial width 600 μm, axial height 100 μm) inside the outer ring layer 124; preparing a suspension of gallium-indium alloy liquid particles (the metal particle material basically fills the second cavity 128), and then injecting it into the second cavity 128 from the entrance of the outer cavity, drying it, and then injecting it into the second cavity 128. A conductive metal layer 129 is formed in the second cavity, and then two wires are fixed on the surface of the conductive metal layer 129 inside the outer ring layer near the inner ring side and the outer ring side, and the diameter of the wires is about 1 mm; the entrance of the outer layer cavity is sealed by using a third mixed rubber, and the two wires pass through the rubber shell of the outer ring layer and remain outside the outer ring layer; finally, an integral sealing ring preform is obtained, which is formed in the radial direction extending from the center of the through hole 121 to the outside, and has an inner ring layer 122, an intermediate layer 123 and an outer ring layer 124 (with a second cavity 128 inside) in sequence;

[0139] Step S3: The sealing ring preform is vulcanized twice; the temperature of the first vulcanization is 175°C and the time is 15 minutes; the temperature of the second vulcanization is 190°C and the time is 3 hours, and finally a vulcanized sealing ring is obtained; the sealing ring structure is three-dimensionally scanned by X-ray, the internal structure is reconstructed, and the porosity of each layer is quantitatively analyzed. The porosity of the inner ring layer, the middle layer, and the outer ring layer are 4.2%, 18.6%, and 27.4% respectively; the sealing ring structure is as shown in FIG. 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 rubber mixing formula of 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 glue is injected into the middle layer cavity of the sealing ring mold (the mold can form an annular cavity structure) at a pressure of 1000 MPa, and an attached middle layer 123 is formed on the axial outer surface of the inner ring layer 122 after preliminary molding; 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 entrance of the middle layer cavity (paraffin basically fills the first cavity, and a space is reserved for the liquid to become solid), and the entrance of the cavity is sealed with the second mixed glue to obtain the middle layer; finally, an integral sealing ring preform is obtained, which is sequentially formed with the inner ring layer 122, the middle layer 123 (with the first cavity 127 inside) and the outer ring layer 124 (with the second cavity 128 inside) in the direction extending radially outward from the center of the through hole 121; the sealing ring structure is as follows 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 by conductive rubber; the formula of the conductive rubber is: 100 parts of fluororubber 23, 30 parts of reinforcing filler carbon black N330, 5 parts of plasticizer fluorinated oil, 2 parts of vulcanizer DCP, 3 parts of accelerator TAIC, and 10 parts of conductive filler silver nanowires, and the conductive rubber is obtained after mixing; the conductive rubber is injected into the second cavity 128 from the entrance of the outer cavity 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; two wires 126 are fixed on the two conductive electrodes respectively, and the diameter of the wires is about 1 mm; the entrance of the outer cavity is sealed with a third mixed rubber, and the two wires pass through the rubber shell of the outer exchange layer and remain outside the outer ring layer; the local cross-sectional structure of the outer ring layer of the sealing ring is as shown Figure 3 shown.

[0145] Example 4

[0146] The difference between Example 4 and Example 1 is that step S23 is further included between step S2 and step S3: placing the sealing ring preform in a micro-fleece mold, injecting the sixth mixed glue into the micro-fleece mold, and distributing micro-fleece 125 on the axial surface of the outer ring layer of the sealing ring preform after curing and molding, as shown in the partial enlarged view Figure 4 As shown; the length of the microvilli is 50 μm, the diameter is 10 μm, and the distance between two adjacent microvilli is 15 μm; the formula of the sixth mixed rubber is: 100 parts of fluororubber, 2 parts of vulcanizing agent DCP, 3 parts of accelerator TAIC, 10 parts of reinforcing filler carbon black N330, and 10 parts of plasticizer fluorinated oil.

[0147] Example 5

[0148] A top cover 1 comprises: a top cover plate 11, the top cover plate 11 is provided with a pole 111;

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

[0150] A top cover sheet 13, the top cover sheet 13 is provided with a pole hole 131 and a wire hole 132, the wire hole 132 includes a first wire hole and a second wire hole; the pole 111 sleeved with a sealing ring 12 passes through the pole hole 131 so that the top cover plate 11 and the top cover sheet 13 are covered, thereby forming a top cover 1;

[0151] Specifically, the structure of the sealing ring 12 includes: in the direction extending radially outward from the center of the through hole 121, the sealing ring 12 includes an inner ring layer 122, an intermediate layer 123 and an outer ring layer 124 in sequence; the inner ring layer 122 is a fluororubber layer; the intermediate layer 123 is a thermal phase change layer, which is used to adjust 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, and the outer ring layer is used to monitor the internal pressure change of the battery cell 2;

[0152] 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 follows Figure 5 shown.

[0153] Example 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 in the housing 4. The housing 4 and the top cover 1 are fixedly covered. The top covers 1 are four types of top covers assembled in Example 14. The schematic diagram of the secondary battery structure is shown in FIG. Figure 6 shown.

[0155] Example 7

[0156] An energy storage system includes the secondary battery 3 of Example 6 and a battery management system BMS; the secondary battery 3 is connected to the battery management system BMS via 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 acts as a buffer layer to absorb mechanical stress; the middle layer material is embedded with a thermal phase change material, which can absorb the heat of the battery to melt and reduce the local temperature of the battery; the outer ring layer material is embedded with a conductive material, which can change resistance under pressure and transmit signals, and can monitor the changes in internal pressure of the battery in real time to warn of the internal pressure of the battery, prevent thermal runaway, and prevent the sealing performance of the battery cell sealing ring from being damaged by long-term heat or pressure; at the same time, the three layers of material are mainly rubber, which cooperate with each other to improve the sealing effect.

[0158] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0159] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in 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; 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 outer ring layer is a pressure sensing layer. A wire is provided on the surface of the outer ring layer. The wire passes through the wire hole to facilitate electrical connection with an external battery management system. The outer ring layer is used to monitor the internal pressure changes of the battery cell.

2. The secondary battery according to claim 1, characterized in that: The wire hole includes 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; And / or, the material of the inner ring layer is a first rubber; And / or, 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; And / or, the material of the middle layer is a third rubber; a first cavity is opened inside the middle layer, and the thermal phase change material is filled in the first cavity.

3. The secondary battery according to claim 2, characterized in that: The thermal phase change material is distributed in the second rubber substrate in a granular or powdery form; And / or, the weight percentage of the thermal phase change material in the thermal phase change rubber is 15% to 25%; And / or, the phase change temperature of the thermal phase change material is 50°C to 70°C; And / or, the thermal phase change material is paraffin; And / or, the thermal phase change material fills the first cavity; And / or, the first cavity is a first annular cavity; The first annular cavity and the intermediate layer are coaxially arranged; 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 material of the outer ring layer is fourth rubber; a second cavity is provided 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.

5. The secondary battery according to claim 4, characterized in that: 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; 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 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; and / or, the conductive wire passes through the axial outer surface of the outer annular layer; And / or, the wire includes a positive wire and a negative wire; And / or, 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 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; 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 positive electrode and the negative electrode are respectively conductive silver paste films or conductive metal sheets; 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; And / or, the radial widths of the inner annular layer, the intermediate layer and the outer annular 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.

7. The secondary battery according to any one of claims 1 to 3, characterized in that: The porosity of the inner annular layer, the middle layer and the outer annular layer increases in sequence.

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 raw rubber, 1-2 parts of vulcanizing agent, 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 device, comprising an energy storage system, characterized in that: The energy storage system is the energy storage system according to claim 11.

Images