Battery pack and electric device

Abstract

The application relates to the field of batteries, and provides a battery pack and an electric device, the battery pack comprising a battery pack and a box body, the battery pack comprising at least one battery monomer, the battery monomer comprising a shell and a battery core arranged in the shell, the set surface of the shell being provided with an explosion-proof valve, the gas production of a single battery monomer in thermal runaway being Q(1) L; and the box body being provided with an exhaust cavity in communication with the explosion-proof valve, the volume of the exhaust cavity being V(1) L, and V(1) / Q(1) satisfying 1.11<=V(1) / Q(1) <=5.29. The box body comprises a first plate body fixedly connected with the set surface of the battery pack and a second plate body arranged in a spaced mode with the first plate body, the first plate body being arranged between the set surface and the second plate body, the first plate body and the second plate body being parallel to the set surface of the battery pack, the exhaust cavity being formed between the first plate body and the second plate body, and the exhaust cavity being in communication with the explosion-proof valve through a communication channel penetrating through the first plate body.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically to a battery pack and an electrical device. Background Technology

[0002] To improve passenger compartment safety, existing battery packs typically have directional pressure relief valves installed on the battery casing to increase the battery's venting rate and form a venting channel corresponding to the battery pack. In this way, when internal thermal runaway occurs in a single battery cell, the high-temperature and high-pressure ejected material from the explosion-proof valve can be quickly guided and discharged.

[0003] As the range and charging speed of battery packs continue to improve, the risk of thermal runaway in existing battery packs increases. In the event of thermal runaway of a single battery cell in an existing battery pack, the pressure relief process of the explosion-proof valve is not timely enough, which can easily lead to fire inside the battery pack and thus trigger the risk of thermal runaway spreading inside the battery pack. Summary of the Invention

[0004] In view of this, the embodiments of this application aim to provide a battery pack and electrical device to solve the technical problem that the risk of thermal runaway in existing battery packs is increasing; after a single battery cell in an existing battery pack undergoes thermal runaway, the pressure relief process of the explosion-proof valve is not timely enough, which can easily lead to fire inside the battery pack and thus cause the risk of thermal runaway spreading inside the battery pack.

[0005] The first aspect of this application provides a battery pack, comprising: A battery pack, the battery pack including at least one battery cell, the battery cell including a housing and a cell disposed inside the housing, the housing having a set surface provided with an explosion-proof valve, the explosion-proof valve including a weak part, the thickness of the weak part being less than the thickness of the set surface, and the gas production of a single battery cell during thermal runaway being Q(1) L; The enclosure is configured to house the battery pack, and the enclosure is provided with an exhaust chamber that is connected to the explosion-proof valve. The volume of the exhaust chamber is V(1)L, and V(1) / Q(1) satisfies 1.11≤V(1) / Q(1)≤5.29.

[0006] The enclosure includes a first plate fixedly connected to the setting surface of the battery pack and a second plate spaced apart from the first plate. The first plate is disposed between the setting surface and the second plate. The first plate and the second plate are parallel to the setting surface of the battery pack. The exhaust chamber is formed between the first plate and the second plate. The exhaust chamber is connected to the explosion-proof valve through a connecting channel penetrating the first plate.

[0007] Another aspect of this application provides an electrical device including the battery pack.

[0008] In the battery pack of this application embodiment, when the ratio of the volume V(1)L of the exhaust chamber to the gas production Q(1)L of a single battery cell during thermal runaway, V(1) / Q(1), satisfies 1.11≤V(1) / Q(1)≤5.29, it can ensure that the exhaust chamber has sufficient buffer volume to promptly accommodate and guide the high-temperature and high-pressure fluid material ejected after the explosion-proof valve ruptures, and reduce the residence time of the high-temperature and high-pressure fluid material in the exhaust chamber. This ensures that the depressurization speed of the battery pack of this application embodiment can meet the requirements, suppress the risk of thermal spread, and effectively ensure the structural rigidity and impact resistance of the battery pack of this application embodiment. It also avoids the safety risk of weakening the structural strength of the battery pack due to the increase of exhaust channels, so that the battery pack of this application embodiment can effectively maintain structural integrity under vibration or collision conditions, and improve overall safety and operational reliability. Attached Figure Description

[0009] It should be understood that the following figures only illustrate certain embodiments of this application and should not be construed as limiting the scope.

[0010] It should be understood that the same or similar reference numerals are used in the accompanying drawings to denote the same or similar elements.

[0011] It should be understood that the accompanying drawings are only schematic, and the dimensions and scales of the elements in the drawings are not necessarily precise.

[0012] Figure 1 This is a perspective view of the battery pack according to an embodiment of this application.

[0013] Figure 2 This is a three-dimensional schematic diagram of the battery pack according to an embodiment of this application.

[0014] Figure 3 This is a partial cross-sectional schematic diagram of the battery pack according to an embodiment of this application.

[0015] Figure 4 This is a partial cross-sectional schematic diagram of some battery cells and the casing of the battery pack according to an embodiment of this application.

[0016] Figure 5 This is a partial internal schematic diagram of the battery pack according to an embodiment of this application.

[0017] Figure 6 This is a partial internal schematic diagram of the battery pack according to an embodiment of this application.

[0018] Figure 7 This is a partial cross-sectional schematic diagram of some battery cells and the casing of another battery pack according to an embodiment of this application.

[0019] Figure 8 This is a cross-sectional schematic diagram of the explosion-proof valve according to an embodiment of this application.

[0020] Figure 9 This is a cross-sectional schematic diagram of another explosion-proof valve according to an embodiment of this application.

[0021] Figure 10 This is a partial cross-sectional view of the battery pack in another direction according to an embodiment of this application.

[0022] Figure 11 This is a schematic diagram of the vehicle structure according to an embodiment of this application.

[0023] Attached image labels: 10. Battery pack; 11. Battery cell; 111. Explosion-proof valve; 112. Groove; 20. Housing; 21. First plate; 211. Through hole; 22. Second plate; 23. Exhaust chamber; 24. Separator; 25. Frame; 251. First wall; 252. Second wall; 26. Main pressure relief valve; 91. Battery pack; 92. Vehicle; 93. Controller.

[0024] X - First direction; Y - Second direction; Z - Height direction; Detailed Implementation Numerous specific details are set forth below to provide an understanding of the structure, function, and use of the embodiments described and illustrated in the specification and figures. It is to be understood that the embodiments described and illustrated herein are non-limiting examples, and thus it will be appreciated that the particular structural and functional details disclosed herein are representative and exemplary. Variations and changes may be made to these embodiments without departing from the scope of the claims.

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] The following is a description of some structures in the embodiments of this application: A battery cell includes a casing, a cell housed inside the casing, and an electrolyte.

[0027] A casing is a component used to provide a space to house and isolate the battery cell and other components from the external environment. A casing generally includes an opening at at least one end and a casing body. The opening in the casing body can be closed by a battery cover, sealing and isolating the internal environment of the battery cell from the external environment. The casing material includes at least one of the following: copper, iron, aluminum, stainless steel, titanium, and aluminum alloy.

[0028] A battery cell is the component within a single battery cell where electrochemical reactions occur; it is the smallest unit within the cell capable of performing electrochemical reactions such as charging and discharging. A battery cell typically consists of a positive electrode, a negative electrode, and a separator located between the positive and negative electrodes. Battery cells can be either wound or stacked. The main shapes of battery cells are cylindrical and cuboid. Lithium-ion battery cells primarily function by the intercalation and deintercalation of lithium ions between the positive and negative electrodes.

[0029] The positive electrode is one of the core components in a battery that carries the positive electrode active material. During charging, metal ions (e.g., lithium ions) are released from the positive electrode active material (oxidation reaction), migrate through the electrolyte, and intercalate into the negative electrode. During discharging, metal ions (e.g., lithium ions in a lithium battery) are released from the negative electrode and intercalated into the positive electrode active material (reduction reaction), thus realizing the storage and release of lithium ions.

[0030] A positive electrode generally includes a positive current collector and a positive active material layer. The positive active material layer is coated on at least one surface of the positive current collector and includes: a positive active material, a conductive agent, and a binder. The positive active material includes, but is not limited to, at least one of the following: lithium phosphates, lithium transition metal oxides and their respective modified compounds, or other conventional materials that can be used as positive active materials for batteries. These positive active materials can be used alone or in combination. The lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, at least one of lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt aluminum oxides, lithium nickel cobalt manganese oxides, and their modified compounds. Lithium nickel cobalt manganese oxides (lithium nickel cobalt manganese oxide) satisfy the general chemical formula LiNi x Co y Mn z M f O2, where 0.1 < x < 1, 0.1 < y < 1, 0.1 < z < 1, and x + y + z + f = 1, M is a dopant element, and M includes at least one of Al, Mg, Ti, Zr, B, P, Nb, Ta, W, Zr, and V.

[0031] The positive electrode current collector includes a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The positive electrode current collector can also include a composite current collector, which may include a polymer material substrate and a metal layer. Composite current collectors are formed by forming a metal material (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0032] The positive electrode conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene and carbon nanofibers.

[0033] The positive electrode binder includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0034] The negative electrode includes a negative current collector and a negative active layer disposed on at least one surface of the negative current collector. The negative current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The negative current collector may also include a composite current collector, which may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0035] The negative electrode active layer includes the negative electrode active material, conductive components, and binders. The negative electrode active material can be carbon-based materials such as graphite, porous carbon, hard carbon, soft carbon, and mesophase carbon microspheres, or silicon-based materials such as elemental silicon, silicon oxides, silicon-carbon composites, and silicon-ammonia composites. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0036] A separator is disposed between the positive and negative electrode plates to separate them and prevent short circuits caused by contact. The separator can be at least one of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF). A coating can also be applied to the separator surface. The coating can be an inorganic coating and / or an organic coating. The inorganic coating material includes at least one of alumina, silicon dioxide, titanium dioxide, magnesium oxide, zirconium oxide, and boehmite; the organic coating includes at least one of aramid coating and PVDF coating. The battery cell also includes tabs, which are located on one side of the positive / negative current collector and are either separate from or integrally formed with the current collector. The tabs are electrically connected to the current collector to conduct current through it. When the tabs and current collector are separate, they can be connected by welding. The tabs are made of a highly conductive metal material (such as copper, aluminum, or nickel).

[0037] The electrolyte is located between the positive and negative electrodes, serving to conduct ions between them. Electrolytes include liquid electrolytes, gel polymer electrolytes, and solid electrolytes; among them, liquid electrolytes refer to electrolytes that are in a liquid state, possessing the function of conducting ions while isolating electrons; liquid electrolytes are composed of chemical substances such as solvents, electrolyte salts, and additives; solvents can be carbonates, carboxylic acid esters, or ethers, etc.; electrolyte salts can be lithium salts, sodium salts, or zinc salts; additives can be ethylene carbonate, fluoroethylene carbonate, propylene sulfite, ethylene sulfite, etc.

[0038] Each battery cell includes terminals, which electrically connect the electrode assembly (cell) located inside the casing to external devices (adjacent batteries or other electrical devices) located outside the casing. The battery can discharge to external devices through the cell output terminal (tab) and terminals, and an external power source can charge the battery through the terminals and cell output terminal (tab). Terminals can be directly electrically connected to the cell tabs or connected via adapters. In this design, the terminals are preferably located on different surfaces from the battery explosion-proof valve, and preferably on the surface of the battery casing opposite the designated surface. This arrangement prevents the temperature of the terminals from affecting the explosion-proof valve's opening, and also prevents thermal runaway substances from affecting the terminals of other batteries and causing heat propagation when the terminals and the explosion-proof valve are on the same side. Terminals are made of metals including, but not limited to, copper, aluminum, aluminum alloys, and copper-aluminum alloys.

[0039] The battery cell also includes an adapter plate. One end of the adapter plate is used for electrical connection to the cell's output terminal (tab), and the other end is used for electrical connection to the battery's output terminal (post), allowing current to flow between the tab and post. The adapter plate is made of at least one of the following conductive metals: aluminum, aluminum alloy, etc. The specific material of the adapter plate is selected based on the materials of the battery's posts and tabs.

[0040] An explosion-proof valve is a component or part that can be actuated to release internal pressure or temperature when the internal pressure or temperature of a battery cell reaches a predetermined threshold. During battery use, explosion-proof valves are mainly used to prevent excessive pressure buildup that could cause deformation or explosion in the event of thermal runaway. They allow gas to escape from the battery, thus reducing internal pressure. The materials used in explosion-proof valves are not limited, including but not limited to aluminum, steel, and alloys. The shape of the explosion-proof valve is also not limited, including square, oblong, elliptical, racetrack-shaped, etc. The type of explosion-proof valve is also not limited, such as a notched explosion-proof valve, which can be formed by stamping or laser etching. The pressure relief mechanism achieves pressure relief by thinning the pressure relief plate to create a weak point. This thinned weak point forms a groove, which can be formed on the side near the battery cell, the side away from the battery cell, or both sides. The groove can be a V-shaped groove, a U-shaped groove, or a trapezoidal groove, etc.

[0041] The explosion-proof valve and the housing can be separate structures, that is, the housing and the explosion-proof valve plate are manufactured separately and can be fixedly connected by welding; or an integrated explosion-proof valve can be used, that is, a thinning area is made on the first surface of the housing, which can be formed by mechanical cutting, laser etching or other methods.

[0042] The explosion-proof valve may include a weak section, the thickness of which is less than the thickness of the setting surface, so that when the internal pressure of the battery cell reaches a certain level, the weak section is broken through to release pressure. The weak section may include a groove, the shape of which may be V-shaped, rectangular, U-shaped, or trapezoidal, with a residual thickness of 0.04~0.4mm. The explosion-proof valve and the setting surface may be integrally connected or separately connected. In the integral connection structure, the housing body is thinned by stamping or laser cutting to form a weak section, which serves as the explosion-proof valve. In the separate connection structure, an explosion-proof plate is set separately, and the setting surface has a through hole. The explosion-proof plate seals the through hole on the setting surface and is welded to the setting surface.

[0043] Research has found that one of the important reasons why the pressure relief of individual battery cells in existing battery packs is not timely is that the gas venting rate inside the battery pack is much lower than the gas production rate of the individual battery cells. This causes heat to accumulate inside the battery pack, and the temperature of each individual battery cell rises too quickly, leading to thermal runaway inside the battery pack. In extreme cases, this can result in the dangerous situation of the battery pack rapidly catching fire and exploding.

[0044] Therefore, as Figure 1As shown, this application embodiment provides a battery pack. The battery pack of this application embodiment can be a complete functional unit that can directly output electrical energy, which is formed by combining multiple battery cells 11 in series and / or parallel to form a battery pack 10, a battery management system (BMS), a thermal management system, an electrical connection system (high voltage / low voltage connectors, wiring harnesses, etc.), structural components (shell, brackets, etc.), and protective components, and placing the above components into a box 20 and sealing it with a cover plate.

[0045] Specifically, the battery pack in this embodiment includes at least a battery pack 10 and a housing 20. The battery pack 10 includes at least one battery cell 11, which includes a housing and a battery cell disposed inside the housing. An explosion-proof valve 111 is provided on the set surface of the housing. The explosion-proof valve 111 includes a weak portion, the thickness of which is less than the thickness of the set surface. The housing 20 is configured to accommodate the battery pack 10, and an exhaust chamber 23 corresponding to and communicating with the explosion-proof valve 111 is provided inside the housing 20. By setting a directional communication channel corresponding to the position of the explosion-proof valve 111, and reasonably controlling the amount of gas generated by thermal runaway of a single battery device and the volume of the exhaust chamber inside the housing, the structural strength of the battery pack is ensured while improving the pressure relief rate of the battery device, thereby enhancing the structural safety of the battery pack.

[0046] It is understood that the housing is equipped with an explosion-proof valve 111 on the setting surface. The setting surface can be the top surface, bottom surface, or any side surface of the battery cell, and there is no limitation here.

[0047] Multiple battery cells 11 with similar capacity and internal resistance can be connected in series or in parallel to form a battery pack 10. Each battery cell 11 can store chemical energy and controllably convert chemical energy into electrical energy. In a recyclable battery, the active material can be activated by charging after discharge so that it can continue to be used.

[0048] The battery cell 11 can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application embodiment is not limited to this. The battery cell 11 typically includes a battery casing, a cell, an adapter plate, and an electrolyte. The battery casing is used to house the cell and the electrolyte, and the battery casing generally includes a battery casing body and a cover plate. At least one positive electrode post and at least one negative electrode post are disposed on the casing and / or the cover plate. The cell includes one or more electrode assemblies, which are formed by stacking or winding positive electrode plates, negative electrode plates, and separators. The separator is located between adjacent positive and negative electrode plates to insulate the positive and negative electrode plates, and at least one end of the electrode assembly has a tab. One end of the adapter plate is electrically connected to the tab, and the other end is electrically connected to the electrode post.

[0049] like Figure 1As shown, the battery cells 11 can be arranged in a linear fashion to form a battery pack 10, or they can be arranged in an array to form a battery pack 10, and there is no limitation on this.

[0050] Specifically, such as Figure 2 As shown, the explosion-proof valve 111 is disposed on the setting surface of the battery cell 11. This setting surface can be the top, bottom, or side surface of the battery cell 11, and is not limited thereto. It is understood that, as... Figure 3 As shown, when the internal pressure of the battery cell 11 is too high, the explosion-proof valve 111 ruptures and forms an opening, which causes the high-temperature and high-pressure fluid material inside the battery cell 11 to spray out along the opening formed after the explosion-proof valve 111 ruptures. The sprayed high-temperature and high-pressure fluid material will flow into the exhaust chamber 23 of the housing 20, which is connected to the explosion-proof valve 111, and flow to the outside along the exhaust chamber 23.

[0051] The enclosure 20 can be a closed or semi-closed structure made of materials such as metal or plastic. It serves as the physical carrier of the battery pack 10, and its design and manufacturing must meet the safety, reliability, and functionality requirements of the battery pack under different usage scenarios. The enclosure 20 provides installation space for the battery pack 10, BMS, cooling system, electrical connection components, etc., and through a reasonable structural design, fixes these components inside the enclosure 20 to ensure a relatively stable position during battery pack operation, avoiding damage to components or loosening of connections due to vibration, impact, or other factors.

[0052] The housing 20 may include a lower housing and an upper housing. The lower housing includes a base plate and a frame that connects to and surrounds the base plate. The upper housing, also generally referred to as a cover, is connected to the frame and has a cover plate opposite to the base plate. The upper and lower housings together form a receiving cavity. The frame and base plate can be integrally formed or processed separately and then fixedly connected. Specifically, the frame and base plate are fixedly connected by welding, riveting, screwing, etc. When the housing 20 is a cube, the frame of the lower housing generally has four side plates surrounding the periphery of the base plate. In other embodiments, the shape of the housing 20 may also be a cylinder or other shapes. The frame mainly serves to support, protect, and connect. The frame can be formed by splicing multiple beams together. The frame can be rectangular, circular, polygonal, etc., without limitation. The beams of the frame can be solid structures or contain cavities. The base plate is the main load-bearing component of the battery pack, used to support and fix the battery pack 10, battery management system, cooling system, and other components inside the battery pack. The housing 20 can be cast from materials such as steel and aluminum alloy, or made from lightweight materials such as glass fiber reinforced composite materials and carbon fiber reinforced composite materials.

[0053] Specifically, such as Figure 3 and Figure 4As shown, in one embodiment of this application, the base plate includes a first plate 21 fixedly connected to the setting surface of the battery pack 10 and a second plate 22 spaced apart from the first plate 21. The first plate 21 and the second plate 22 can be fixedly connected to the frame respectively, or they can be fixedly connected to the frame through the same fixing point. The first plate 21 is disposed between the setting surface and the second plate 22. The first plate 21 and the second plate 22 are parallel to the setting surface of the battery pack. An exhaust chamber 23 is formed between the first plate 21 and the second plate 22. The exhaust chamber 23 is connected to the explosion-proof valve 111 through a connecting channel penetrating the first plate 21.

[0054] The first plate 21 is fixedly connected to the set surface of the explosion-proof valve 111 of the battery pack 10. This connection can be a direct contact connection such as welding, bonding, riveting, or bolting, or an indirect contact connection achieved through an intermediate layer such as a heat insulation pad. The adhesive used for bonding can be polyurethane, epoxy resin, acrylic, silicone, etc. The second plate 22 is arranged parallel or nearly parallel to the first plate 21, with the space between them forming the exhaust chamber 23. A connecting channel passes through the first plate 21 to connect the exhaust chamber 23 to the corresponding explosion-proof valve 111.

[0055] The exhaust chamber 23 can be a single unit or multiple units. When there are multiple exhaust chambers 23, adjacent exhaust chambers 23 are separated by separators. The arrangement direction of the multiple exhaust chambers can be parallel to the stacking direction of the battery cells in the battery pack or perpendicular to the stacking direction of the battery cells in the battery pack. The connecting channel can be a through hole, a gap, a groove, or other structure. When the connecting channel is a through hole, the shape of the through hole can include circular, square, elliptical, etc.

[0056] Therefore, in the battery pack of this application embodiment, an exhaust chamber 23 can be formed between the first plate 21 and the second plate 22. The high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111 of the battery cell 11 flows to the exhaust chamber 23 through the connecting channel penetrating the first plate 21, and then flows to the outside along the exhaust chamber 23. This effectively limits the ejection path of the high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111, and can prevent the high-temperature and high-pressure fluid material from spreading inside the battery pack after being ejected from the explosion-proof valve 111. This significantly reduces the risk of the high-temperature ejected material directly heating adjacent battery cells 11 or other electrical connectors in the housing 20, reduces the impact of thermal runaway of a single battery pack, and improves the thermal safety isolation performance of the battery pack.

[0057] The first plate 21 and the second plate 22 can be an integral structure or a separate structure, preferably a separate structure. The first plate 21 and / or the second plate 22 can be fixed to the battery pack housing by riveting or by welding.

[0058] The material of the first plate 21 includes at least one of aluminum alloy, iron, stainless steel, etc.; the material of the second plate 22 includes at least one of aluminum alloy, iron, stainless steel, etc.

[0059] Specifically, in the battery pack of this application embodiment, the gas production of a single battery cell 11 during thermal runaway is Q(1) L; and the volume of the exhaust chamber 23 is V(1) L, where V(1) / Q(1) satisfies 1.11≤ V(1) / Q(1) ≤5.29.

[0060] Specifically, the test method for the volume V(1)L of the exhaust chamber 23 is as follows: The battery pack was disassembled, and the exhaust chamber was scanned using a laser scanner. The data was processed using software such as Geomagic Control X and PolyWorks to establish a three-dimensional model of the exhaust chamber and calculate the specific volume of the exhaust chamber, denoted as V(1)L.

[0061] The test method for the gas production Q(1)L of a single battery cell 11 during thermal runaway is as follows: Disassemble the battery pack, remove the individual battery cells, and let the individual battery cells stand at 25°C for 1 hour. Then, charge them at 0.33C to the upper limit voltage at 25°C, let them stand for 20 minutes, and then discharge them at 0.33C to the lower limit voltage. Let them stand for 20 minutes. Repeat this cycle 3 times. Record the discharge capacity of the third cycle as the actual capacity C1 of the individual battery cells. Charge the individual battery cells to 80% SOC at 0.33C1 (0.33 times the actual capacity). Measure the amount of gas generated during thermal runaway of the individual battery cells according to standard QC / T 1239-2025 and record it as Q(1) L. When the positive electrode active material includes nickel-cobalt-manganese ternary materials, the upper limit voltage is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material includes lithium iron phosphate, the upper limit voltage is 3.65V and the lower limit voltage is 2.5V.

[0062] The method for controlling the gas production Q(1)L of a single battery cell 11 during thermal runaway is as follows: When the positive electrode active material remains unchanged, the compaction density of the positive electrode sheet (2.4~3.8 g / cm³) can be adjusted. 3 Adjust the amount of gas generated by a single cell 11 during thermal runaway; the greater the compaction density of the positive electrode sheet, the greater the amount of gas generated by the cell during thermal runaway under the same charge state, and the smaller the compaction density of the positive electrode sheet, the smaller the amount of gas generated by the cell during thermal runaway under the same charge state.

[0063] In a specific embodiment, the compaction density of the positive electrode sheet ranges from 2.4 g / cm³ to 3.8 g / cm³. Specific values ​​such as 2.4 g / cm³, 2.55 g / cm³, 2.7 g / cm³, 2.85 g / cm³, 3.0 g / cm³, 3.15 g / cm³, 3.3 g / cm³, 3.45 g / cm³, 3.6 g / cm³, and 3.8 g / cm³ can be selected, or other reasonable specific values ​​can be selected within the above range. No restrictions are imposed here.

[0064] The amount of gas produced can also be adjusted by changing the type of positive electrode active material, which can include lithium iron phosphate or lithium nickel cobalt manganese oxide. Specifically, when lithium nickel cobalt manganese oxide is used, the amount of gas produced by the battery cell during thermal runaway can also be adjusted by changing the molar percentage of nickel in the lithium nickel cobalt manganese oxide. The molar percentage of nickel in lithium nickel cobalt manganese oxide ranges from 20% to 90%. A higher molar percentage of nickel results in a higher amount of gas produced by the battery cell during thermal runaway, and vice versa.

[0065] In a specific embodiment, the molar percentage of nickel in lithium nickel cobalt manganese oxide ranges from 20% to 90%, and specific values ​​such as 20%, 28%, 36%, 44%, 52%, 60%, 68%, 76%, 83%, and 90% can be selected, or other reasonable specific values ​​can be selected within the above range, without limitation.

[0066] The positive electrode includes a positive current collector and a positive active material layer coated on the surface of the positive current collector. The negative electrode includes a negative current collector and a negative active material layer coated on the surface of the negative current collector. The ratio of the thickness of the positive active material layer to the thickness of the positive current collector can be adjusted, and / or the ratio of the thickness of the negative active material layer to the thickness of the negative current collector can adjust the amount of gas generated by the battery cell during thermal runaway. The larger the ratio of the thickness of the active material layer to the thickness of the current collector, the greater the amount of gas generated, and vice versa.

[0067] Under the same capacity and state of charge, the gas production of a single battery cell with lithium nickel cobalt manganese oxide as the positive electrode active material is greater than that of a single battery cell with lithium iron phosphate as the positive electrode active material.

[0068] The preparation method of battery cell 11 is as follows: (1) Preparation of the positive electrode: The positive electrode active material, conductive agent (e.g., acetylene black), and binder (e.g., PVDF) are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, the positive electrode sheet is obtained by rolling and slitting.

[0069] Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98): (4~1): (4~1).

[0070] (2) Preparation of negative electrode: The negative electrode active material, conductive agent (e.g., acetylene black), thickener (e.g., carboxymethyl cellulose (CMC)), and binder (e.g., styrene-butadiene rubber (SBR)) are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, dried at room temperature, and then transferred to an oven for further drying. Finally, the negative electrode sheet is obtained by rolling and slitting.

[0071] Specifically, the ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0072] (3) Preparation of electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0073] (4) Preparation of the diaphragm: Polyethylene film is selected as the diaphragm.

[0074] (5) Preparation of lithium-ion batteries: The above-mentioned positive electrode sheet, separator, and negative electrode sheet are sequentially wound or stacked to form a bare cell; the bare cell is placed in the battery casing, which is a square casing, the battery is dried, electrolyte is injected, and after encapsulation, settling, formation, and volume adjustment, a lithium-ion battery is obtained.

[0075] In the selection of materials for the aforementioned battery, this application may also select other materials, not limited to those limited by the above preparation method. The positive electrode active material may be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate. The conductive agent in the positive electrode sheet may also be selected from one or more of graphite, superconducting carbon, Ketjen black, Super P, carbon nanotubes, graphene, and carbon nanofibers. The binder in the positive electrode sheet may also be selected from one or more of polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan. The positive electrode current collector may also be selected from one or more of stainless steel with surface silver plating, stainless steel, aluminum, nickel, carbon electrode, carbon, nickel, and titanium. The positive electrode current collector may also include a composite current collector, which may include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming metallic materials (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on a polymer substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0076] The negative electrode active material can be selected from one or more of the following negative electrode active main materials: artificial graphite, natural graphite, silicon carbide, silicon oxide, lithium titanate, etc.; the conductive agent in the negative electrode sheet can be selected from one or more of the following: conductive carbon black, conductive graphite, carbon nanotubes, graphene, carbon fiber, etc.; the binder in the negative electrode sheet can be selected from one or more of the following: styrene-butadiene rubber, polyacrylic acid and its salts, sodium alginate, etc.; the thickener in the negative electrode sheet can be selected from one or more of the following: sodium carboxymethyl cellulose, polyacrylonitrile multi-component copolymer, etc.; the negative electrode current collector can also be selected from one or more of the following: stainless steel with silver plating, stainless steel, copper, nickel, carbon electrode, carbon, nickel, titanium, etc.; the negative electrode current collector can also include composite current collectors, which can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0077] Battery pack manufacturing method Battery cells are manufactured according to the above-described battery preparation method. Ten battery cells are stacked into a group, and a heat insulation component is placed between adjacent battery cells to obtain a battery pack. Three battery packs are prepared and placed on the first plate. The three battery packs are electrically connected, and the upper casing is sealed to the frame. The first plate is sealed and fixedly connected to the frame. A second plate is set on the side of the first plate away from the battery pack and is spaced apart from the first plate to form an exhaust chamber. The second plate is sealed and fixedly connected to the frame. A main pressure relief valve is set on the frame. The main pressure relief valve is connected to the explosion-proof valve of the battery cell through the exhaust chamber. The first plate is provided with a through hole corresponding to the position of the battery explosion-proof valve. The explosion-proof valve of the battery cell is provided with a corresponding through hole.

[0078] The test method for battery thermal runaway testing is as follows: According to the above-described battery pack preparation method, one battery pack was made for each embodiment and comparative example. The V(1) and Q(1) values ​​of each embodiment and comparative example are shown in the table below. Except for the above, the other structures are the same. Each battery cell in the battery pack was charged to the upper limit voltage at a charging rate of 0.33C. Heating plates were set on two sides of any battery cell in the battery pack along the stacking direction. The heating plates were set between the heat insulation component and the side of the battery cell. The battery cell was heated at a heating rate of 5±2℃ / min until thermal runaway occurred. The timing was started from the occurrence of thermal runaway of the battery cell. The time of thermal runaway of other battery cells in the battery pack was observed and recorded. If the thermal runaway time of other battery cells was greater than or equal to 180min, the test result was good. If the thermal runaway time of other battery cells was less than 180min and greater than or equal to 120min, the test result was qualified. If the thermal runaway time of other battery cells was less than 120min, the test result was unqualified.

[0079] When the positive electrode active material includes lithium nickel cobalt manganese oxide, the upper limit voltage is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material includes lithium iron phosphate, the upper limit voltage is 3.65V and the lower limit voltage is 2.5V.

[0080] The positive electrode active materials used in the examples and comparative examples in this test were selected from LiNi. 0.6 Co 0.2 Mn 0.2 O2 or lithium iron phosphate, other positive electrode materials meet the above test requirements, the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; negative electrode active material is selected from artificial graphite, the ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2, the cell style is selected as wound cell, other cell types meet the above test requirements.

[0081] The test method for exhaust cavity deformation testing is as follows: According to the above-described battery pack preparation method, one battery pack was made for each embodiment and comparative example. The V(1) and Q(1) values ​​of each embodiment and comparative example are shown in the table below. Apart from this, the other structures are the same. The battery packs of each embodiment and comparative example were placed in a vibration table. According to the national standard GB38031-2020.8.2, under the conditions of random vibration in the Z / Y / X directions and sinusoidal fixed-frequency vibration, the battery pack was disassembled after continuous random vibration for 12 hours and sinusoidal fixed-frequency vibration for 2 hours in each direction. The deformation of the first plate and / or the second plate constituting the exhaust chamber was observed and measured. If the deformation of the first plate and / or the second plate is greater than 3 mm, it is unqualified. If the deformation of the first plate and / or the second plate is less than or equal to 3 mm and greater than 1 mm, the test result is qualified. If the deformation of the first plate and / or the second plate is less than or equal to 1 mm, the test result is good.

[0082] The parameters and test results of Examples 1 to 18 and Comparative Examples 1 to 4 of this application are as follows: In Examples 1-17 and Comparative Examples 1-5, the set surface is the surface of the battery cell housing facing the bottom plate of the battery pack. In Examples 18 and Comparative Example 6, the set surface is the surface of the battery cell housing facing away from the bottom plate.

[0083] It can be seen that the V(1) / Q(1) values ​​of comparative examples 1, 4, 5, and 6 are less than 1.11, and the battery thermal runaway test results are unqualified. According to the analysis, when the ratio of the volume V(1)L of the exhaust chamber 23 to the gas production Q(1)L of a single battery cell 11 during thermal runaway is less than 1.11, the volume of the exhaust chamber 23 is relatively insufficient. The pressure relief efficiency after the explosion-proof valve 111 of any battery cell 11 breaks is low, and the high-temperature and high-pressure fluid material ejected stays in the exhaust chamber 23 for a long time, which can easily cause other battery cells 11 to experience chain thermal runaway.

[0084] The V(1) / Q(1) values ​​of Comparative Examples 2 and 3 are greater than 5.29, and the results of the exhaust cavity deformation test are unqualified. According to the analysis, when V(1) / Q(1) is greater than 5.29, the exhaust cavity 23 needs to occupy more space, thereby weakening the structural rigidity of the entire battery pack, and the battery pack housing 20 is prone to deformation.

[0085] In all embodiments, the V(1) / Q(1) values ​​satisfy 1.11≤ V(1) / Q(1) ≤5.29, and the battery thermal runaway test results and exhaust chamber deformation test results are all qualified or good. According to the analysis, in the battery pack of this application embodiment, when the ratio V(1) / Q(1) of the volume V(1)L of the exhaust chamber 23 to the gas production Q(1)L of a single battery cell 11 during thermal runaway satisfies 1.11≤ V(1) / Q(1) ≤5.29, it can be ensured that the exhaust chamber 23 has sufficient buffer volume to timely accommodate and guide the high-temperature and high-pressure fluid material ejected after the explosion-proof valve 111 ruptures, and reduce the residence time of the high-temperature and high-pressure fluid material in the exhaust chamber 23 to ensure that the depressurization speed of the battery pack of this application embodiment can meet the requirements, suppress the risk of thermal propagation, and also effectively ensure the structural rigidity and impact resistance of the battery pack of this application embodiment, so that the battery pack of this application embodiment can effectively maintain structural integrity under vibration or collision conditions, and improve overall safety and operational reliability.

[0086] In a specific embodiment, V(1) ranges from 5 to 70, Q(1) ranges from 3 to 60, the orthographic projection area of ​​the exhaust chamber 23 on the plane of the first plate ranges from 320,000 mm² to 2,700,000 mm², and the height of the exhaust chamber 23 ranges from 6 mm to 20 mm; V(1) / Q(1) ranges from 1.11 to 5.29, and specific values ​​such as 1.11, 1.58, 2.05, 2.52, 2.99, 3.46, 3.93, 4.40, 4.87, and 5.29 can be selected, or other reasonable specific values ​​can be selected within the above range, without limitation.

[0087] Furthermore, in one embodiment of this application, the battery pack of this embodiment satisfies 1.3≤ V(1) / Q(1) ≤4.51. As shown in the table, the battery packs of embodiments 9-16 all satisfy 1.3≤ V(1) / Q(1) ≤4.51, and the battery thermal runaway test results and exhaust cavity deformation test results are both good.

[0088] In the battery pack of this application embodiment, when the ratio of the volume V(1)L of the exhaust chamber 23 to the gas production Q(1)L of a single battery cell 11 during thermal runaway, V(1) / Q(1) satisfies 1.3≤V(1) / Q(1)≤4.51, it can further ensure that the exhaust chamber 23 has sufficient buffer volume to timely accommodate and guide the high-temperature and high-pressure fluid material ejected after the explosion-proof valve 111 ruptures, and reduce the residence time of the high-temperature and high-pressure fluid material in the exhaust chamber 23. This ensures that the depressurization speed of the battery pack of this application embodiment can meet the requirements, suppress the risk of thermal spread, and further ensure the structural rigidity and impact resistance of the battery pack of this application embodiment. This enables the battery pack of this application embodiment to effectively maintain structural integrity under vibration or collision conditions, and improve overall safety and operational reliability.

[0089] In a specific embodiment, V(1) / Q(1) ranges from 1.3 to 4.51. Specific values ​​such as 1.3, 1.66, 2.02, 2.38, 2.74, 3.1, 3.46, 3.82, 4.18, and 4.51 can be selected, or other reasonable specific values ​​can be selected within the above range. No restrictions are imposed here.

[0090] In a specific embodiment, V(1) ranges from 7 to 65. Specific values ​​such as 7, 13, 20, 26, 32, 39, 45, 51, 58, and 65 can be selected. Other reasonable specific values ​​can also be selected within the above range. This can further ensure that the exhaust chamber 23 has sufficient buffer volume to promptly accommodate and guide the high-temperature and high-pressure fluid material ejected after the explosion-proof valve 111 ruptures, reduce the residence time of the high-temperature and high-pressure fluid material in the exhaust chamber 23, ensure that the pressure relief speed of the battery pack in this embodiment meets the requirements, suppress the risk of heat spread, and further ensure the structural rigidity and impact resistance of the battery pack in this embodiment. This allows the battery pack in this embodiment to effectively maintain structural integrity under vibration or collision conditions, improving overall safety and operational reliability.

[0091] In a specific embodiment, Q(1) ranges from 5 to 50, and specific values ​​such as 5, 10, 15, 20, 26, 31, 37, 42, 46, and 50 can be selected. Other reasonable specific values ​​can also be selected within the above range. This can limit the amount of gas generated by a single battery cell 11 during thermal runaway while improving the energy density of the battery cell.

[0092] In one embodiment of this application, the setting surface of the battery cell 11 is the top surface of the battery cell 11, and the first plate 21, the second plate 22 and the exhaust cavity 23 are all located above the battery cell 11; along the direction perpendicular to the setting surface, the extension height of the exhaust cavity 23 is H(1) mm, and H(1) mm satisfies 8mm≤H(1) mm≤20mm.

[0093] It is understandable that the top surface of the battery cell 11 is the upper surface of the battery cell 11 in the normal placement height direction. The explosion-proof valve 111 of the battery cell 11 is set on the top surface of the battery cell 11, and the first plate 21, the exhaust chamber 23 and the second plate 22 are located above the battery cell 11 in sequence. After the explosion-proof valve 111 breaks, it will spray high temperature and high pressure fluid substances upward of the battery cell 11.

[0094] Under the above structure, the extension height H(1) of the exhaust chamber 23 is the dimension of the exhaust chamber 23 in the height direction of the battery cell 11. When the extension height of the exhaust chamber 23 is less than 8 mm, the extension height of the exhaust chamber 23 is too small, the volume of the exhaust chamber 23 is small, the high temperature and high pressure fluid material ejected by the explosion-proof valve 111 has a large flow resistance in the exhaust chamber 23, the buffering effect of the exhaust chamber 23 on the high temperature and high pressure fluid material is insufficient, and the buffering effect on external impact is also relatively poor. When H(1) mm is greater than 20 mm, the exhaust chamber 23 needs to occupy a large space, which can easily affect the energy density of the battery pack in this embodiment.

[0095] Therefore, when the extension height of the exhaust chamber 23 is H(1) mm, satisfying 8 mm ≤ H(1) mm ≤ 20 mm, the buffering effect of the exhaust chamber 23 on the high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111 can be effectively improved, the pressure relief efficiency of the exhaust chamber 23 can be improved, and the high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111 can be prevented from breaking through the second plate 22 and being ejected into the passenger compartment of electric vehicles and other electrical devices. It can also improve the buffering effect of the first plate 21 and the second plate 22 on external impacts. It can also effectively save the space occupied by the exhaust chamber 23 and improve the energy density of the battery pack in this embodiment. In a specific embodiment, the range of H(1) mm is 8 mm to 20 mm. Specific values ​​such as 8 mm, 9.5 mm, 11 mm, 12.5 mm, 14 mm, 15.5 mm, 17 mm, 18.5 mm, 19 mm, and 20 mm can be selected. Other reasonable specific values ​​can also be selected within the above range, which are not limited here.

[0096] like Figure 2 and Figure 4 As shown, in one embodiment of this application, the setting surface of the battery cell 11 is the bottom surface of the battery cell 11, and the first plate 21, the second plate 22 and the exhaust cavity 23 are all located below the battery cell 11; along the direction perpendicular to the setting surface, the extension height of the exhaust cavity 23 is H(2) mm, and H(2) mm satisfies 8mm≤H(2) mm≤18mm.

[0097] It is understandable that the bottom surface of the battery cell 11 is the lower end surface in the normal placement height direction of the battery cell 11, the explosion-proof valve 111 of the battery cell 11 is set on the bottom surface of the battery cell 11, and the first plate 21, the exhaust chamber 23 and the second plate 22 are located below the battery cell 11 in sequence. After the explosion-proof valve 111 breaks, it will spray high temperature and high pressure fluid material downwards of the battery cell 11.

[0098] Under the above structure, the extension height H(2) of the exhaust chamber 23 is the dimension of the exhaust chamber 23 in the height direction of the battery cell 11. When the extension height of the exhaust chamber 23 is less than 8 mm, the extension height of the exhaust chamber 23 is too small, the volume of the exhaust chamber 23 is small, the high temperature and high pressure fluid material ejected by the explosion-proof valve 111 has a large flow resistance in the exhaust chamber 23, and the buffering effect of the exhaust chamber 23 on the high temperature and high pressure fluid material is insufficient. When H(2) mm is greater than 18 mm, the exhaust chamber 23 needs to occupy a large space, which can easily affect the energy density of the battery pack in this embodiment.

[0099] Therefore, when the extension height of the exhaust chamber 23 is H(2) mm, satisfying 8 mm ≤ H(1) mm ≤ 18 mm, the buffering effect of the exhaust chamber 23 on the high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111 can be effectively improved, the pressure relief efficiency of the exhaust chamber 23 can be improved, the high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111 can be prevented from breaking through the second plate 22 and being ejected to the outside, and the buffering effect of the first plate 21 and the second plate 22 on external impacts can be improved, reducing the damage to the battery pack of this embodiment after being impacted by the bottom collision, ensuring the structural safety and reliability of the battery pack; it can also effectively save the space occupied by the exhaust chamber 23 and improve the energy density of the battery pack of this embodiment. In a specific embodiment, the range of H(2) mm is 8 mm to 18 mm, and specific values ​​such as 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, and 18 mm can be selected, or other reasonable specific values ​​can be selected within the above range, which are not limited here.

[0100] like Figure 6 As shown, in one embodiment of this application, the orthographic projection of the explosion-proof valve 111 on the first plate 21 at least partially coincides with the orthographic projection of the connecting channel on the first plate 21. Since the orthographic projection of the explosion-proof valve 111 on the first plate 21 at least partially coincides with the orthographic projection of the connecting channel on the first plate 21, at least a portion of the high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111 of the battery cell 11 can flow directly along the connecting channel penetrating the first plate 21 to the exhaust chamber 23.

[0101] like Figure 6As shown, in one embodiment of this application, the explosion-proof valve 111 falls entirely within the orthographic projection of the connecting channel onto the first plate 21. Because the explosion-proof valve 111 falls entirely within the orthographic projection of the connecting channel onto the first plate 21, it is convenient for all the high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111 of the battery cell 11 to flow directly along the connecting channel penetrating the first plate 21 to the exhaust chamber 23.

[0102] like Figure 4 As shown, in one embodiment of this application, the orthographic projection of a single exhaust chamber 23 on the first plate 21 and the orthographic projection of the explosion-proof valve 111 of at least two adjacent battery cells 11 on the first plate 21 are at least partially overlapped.

[0103] Specifically, since the battery cells 11 can be arranged in a linear fashion to form a battery pack 10, or arranged in an array to form a battery pack 10, the exhaust chamber 23 can be a continuous long chamber extending along the battery arrangement direction, so as to ensure that the orthographic projection of the exhaust chamber 23 on the first plate 21 and the orthographic projection of the explosion-proof valve 111 of at least two adjacent battery cells 11 on the first plate 21 are at least partially overlapped.

[0104] In this way, the high-temperature and high-pressure fluid material ejected after the explosion-proof valves 111 of at least two adjacent battery cells 11 corresponding to a single exhaust chamber 23 rupture can be directly ejected into the exhaust chamber 23, effectively increasing the pressure relief rate of the battery cell 11 during thermal runaway, optimizing the space utilization of the exhaust chamber 23, reducing the number of independent exhaust chambers 23 in the housing 20, and simplifying the structural design and manufacturing process of the housing 20. It is also conducive to the rapid extraction of high-temperature and high-pressure fluid material generated after thermal runaway.

[0105] Furthermore, in one embodiment of this application, under the premise that the orthographic projection of the exhaust chamber 23 on the first plate 21 and the orthographic projection of the explosion-proof valve 111 of at least two adjacent battery cells 11 on the first plate 21 are at least partially overlapped, V(1) / Q(1)≥2, that is, the ratio of the volume V(1)L of the exhaust chamber 23 to the gas production Q(1)L of a single battery cell 11 during thermal runaway is greater than that of the exhaust chamber 23. This enables the exhaust chamber 23 to effectively cope with the situation where two or more battery cells 11 experience thermal runaway successively or simultaneously, effectively providing a larger gas containment buffer space, ensuring that even under abnormal conditions, the exhaust chamber 23 still has sufficient volume for depressurization, significantly improving the exhaust safety redundancy of the battery pack in extreme conditions in this application embodiment, further reducing the risk of thermal spread of battery cells 11 in the battery pack, and further improving the safety of the battery pack in this application embodiment.

[0106] Specifically, such as Figure 5As shown, in one embodiment of this application, the first plate 21 is provided with a through hole 211 corresponding to the explosion-proof valve 111 of the battery cell 11. That is, the through hole 211 can be processed on the first plate 21 by processes such as stamping or laser cutting. The position of the through hole 211 corresponds one-to-one with the position of the explosion-proof valve 111 of the battery cell 11. Each explosion-proof valve 111 of the battery cell 11 is directly connected to the exhaust chamber 23 through the corresponding through hole 211, ensuring that the high-temperature, high-pressure fluid ejected from the explosion-proof valve 111 can be directly discharged to the corresponding exhaust chamber 23.

[0107] like Figure 5 As shown, in one embodiment of this application, the battery pack 10 includes at least two battery cells 11 arranged along a set direction; the set direction is perpendicular to the length direction of the set surface of the battery cell 11, and along the set direction, the spacing between adjacent through holes 211 of the first plate 21 is D(2) mm, which satisfies 8mm≤D(2) mm≤50mm.

[0108] That is, the setting direction is the direction in which the battery cell 11 is arranged in the battery pack 10, which can be the length direction or the width direction of the battery cell 11. The spacing D(2) between adjacent through holes 211 is the shortest distance between the edges of two adjacent through holes 211 on the first plate 21 along the setting direction.

[0109] When the distance between adjacent through holes 211 of the first plate 21 along the set direction is D (2) mm less than 8 mm, the structural strength of the first plate 21 is poor and it is prone to structural deformation. When D (2) mm is greater than 50 mm, it is easy to affect the area that can be arranged in the through holes 211, thereby affecting the pressure relief effect of the battery pack in this embodiment.

[0110] Therefore, when the spacing between adjacent through holes 211 of the first plate 21 along the aforementioned set direction is D (2) mm, satisfying 8 mm ≤ D (2) mm ≤ 50 mm, it can be ensured that there is a relatively wide solid portion between adjacent through holes 211, thereby ensuring the structural strength of the first plate 21, ensuring that the first plate 21 is not prone to cracking or excessive deformation when subjected to internal stress or external vibration of the battery pack, ensuring the supporting function of the first plate 21, and also ensuring the area where the through holes 211 can be arranged, improving the pressure relief effect of the battery pack in this embodiment, thereby effectively improving the overall structural safety and thermal safety performance of the battery pack in this embodiment. In a specific embodiment, the range of D (2) mm is from 8 mm to 50 mm, and specific values ​​such as 8 mm, 12 mm, 16 mm, 20 mm, 24 mm, 28 mm, 32 mm, 38 mm, 44 mm, and 50 mm can be selected, or other reasonable specific values ​​can be selected within the above range, which are not limited here.

[0111] Furthermore, in one embodiment of this application, the area S(1) mm² of the through hole 211 is greater than the area S(2) mm² of the region enclosed by the corresponding explosion-proof valve 111.

[0112] When the explosion-proof valve 111 includes a weak part, the area of ​​the region enclosed by the explosion-proof valve 111 is the area of ​​the region enclosed by the weak part. If the weak part is a discontinuous structure, the area of ​​the region enclosed by connecting the endpoints of adjacent weak parts together with a straight line is denoted as S(2) mm².

[0113] Since the area S(1)mm² of the through hole 211 is larger than the area S(2)mm² of the area enclosed by the corresponding explosion-proof valve 111, it can be ensured that the high-temperature and high-pressure fluid material is not easily obstructed by the hole wall of the through hole 211 in the passage from the explosion-proof valve 111 to the exhaust chamber 23. This ensures that the high-temperature and high-pressure fluid material can pass through the through hole 211 on the first plate 21 quickly, accelerate the depressurization rate inside the battery pack, and reduce the residence time of the high-temperature and high-pressure fluid material in the battery pack.

[0114] like Figure 7 As shown, in one embodiment of this application, at least two exhaust chambers 23 are provided inside the housing 20, and the exhaust chambers 23 are respectively connected to at least one explosion-proof valve 111; the exhaust chambers 23 are configured to be isolated from each other by a separator 24, and the distance between adjacent exhaust chambers 23 is D(1) mm, where D(1) mm satisfies 5 mm ≤ D(1) mm ≤ 30 mm.

[0115] A separator 24 is provided between the first plate 21 and the second plate 22 to isolate the two exhaust chambers 23. The distance D(1) between adjacent exhaust chambers 23 is the shortest distance between adjacent exhaust chambers 23. When the distance D(1) mm between adjacent exhaust chambers 23 is less than 5 mm, the separator 24 has a poor separating effect and is easily broken by the high-temperature and high-pressure fluid material sprayed from the explosion-proof valve 111. When D(1) mm is greater than 30 mm, it can easily affect the usable volume of the exhaust chamber 23, thereby affecting the pressure relief efficiency of the battery pack in this embodiment.

[0116] Therefore, when the distance between adjacent exhaust chambers 23 is D(1) mm, satisfying 5 mm ≤ D(1) mm ≤ 30 mm, it can be ensured that the separator 24 has sufficient width to achieve effective separation, preventing the high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111 from breaking through the separator 24 and spreading to adjacent exhaust chambers 23. At the same time, it ensures that the cross-sectional area of ​​each exhaust chamber 23 meets the requirements, thereby improving the pressure relief efficiency of the battery pack in this embodiment. In a specific embodiment, the range of D(1) mm is 5 mm to 30 mm, and specific values ​​such as 5 mm, 8 mm, 11 mm, 14 mm, 17 mm, 20 mm, 23 mm, 26 mm, 28 mm, and 30 mm can be selected. Other reasonable specific values ​​can also be selected within the above range, which are not limited here.

[0117] The material of the separator 24 may include plastic, metal, or foam. Plastics include polycarbonate, polyamide, acrylonitrile-butadiene-styrene copolymer, etc.; metals include aluminum alloy, steel, etc.; and foam materials include rigid PET foam, silicone foam, etc. The separator can be fixed to the first plate by welding, or by adhesive, snap-fit, etc.

[0118] When the first plate 21 is a heat exchange plate, the first plate 21 includes a heat exchange channel, which is at least partially located within the exhaust chamber to form a partition. The heat exchange channel is configured for the flow of a heat exchange medium; the heat exchange channel and the clearance hole are spaced apart. The heat exchange medium can be a gas (air), a liquid (such as water, alcohol, refrigerant, oil, etc.), or a solid (such as thermally conductive adhesive, thermally conductive solder paste, etc.). The heat exchange channel has an inlet and an outlet for the heat exchange medium. The heat exchange medium can enter the heat exchange channel through the inlet and, after heat exchange with the battery cells, exit through the outlet, thereby achieving heat exchange with the battery cells.

[0119] In one embodiment of this application, the height of the separator 24 in the exhaust chamber 23 is less than the height of the exhaust chamber. Since the height of the separator 24 in the exhaust chamber 23 is less than the height of the exhaust chamber, it is convenient to depressurize the battery cell 11 that has experienced thermal runaway, and prevent the battery pack from exploding due to slow depressurization of the thermal runaway battery caused by slow exhaust rate, thereby improving the working safety of the battery pack.

[0120] like Figure 7 As shown, in one embodiment of this application, at least two partitions 24 are provided inside the housing 20. At least some of the partitions 24 are spaced apart along the stacking direction of the battery cells 11. The above structure can further prevent the high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111 from breaking through the partitions 24 and spreading to the adjacent exhaust chambers 23, while ensuring that the cross-sectional area of ​​each exhaust chamber 23 meets the requirements, thereby improving the pressure relief efficiency of the battery pack in this embodiment of the application.

[0121] like Figure 7 As shown, along the stacking direction of the battery cells 11, the spacing between adjacent separators 24 is less than the extension length of a single battery cell 11 in the stacking direction. It is understood that when the spacing between adjacent separators 24 is less than the extension length of a single battery cell 11 in the stacking direction, the separating function of the separators 24 can be guaranteed while ensuring that the cross-sectional area of ​​each exhaust chamber 23 meets the requirements, thus effectively improving the structural strength of the battery pack in this embodiment.

[0122] Furthermore, in one embodiment of this application, for the structure in which the spacing distance between adjacent separators 24 is less than the extension length of a single battery cell 11 in the stacking direction of the battery cell 11, the gas production Q1 L of a single battery cell 11 during thermal runaway satisfies 3L≤Q(1) L≤55L, which can effectively limit the gas production of a single battery cell 11 during thermal runaway and improve the exhaust rate of a single battery cell 11.

[0123] like Figure 5 As shown, in one embodiment of this application, the ratio of the area S(2) mm² of the region enclosed by the explosion-proof valve 111 to the area S(3) mm² of the set surface of the battery cell 11 is S(2) / S(3)≤0.2, and V(1) / Q(1)≥1.8.

[0124] When the ratio of the area S(2) mm² of the region enclosed by the explosion-proof valve 111 to the area S(3) mm² of the set surface of the battery cell 11 is S(2) / S(3)≤0.2, the area of ​​the explosion-proof valve 111 is relatively small, resulting in a relatively limited pressure relief and exhaust capacity of the battery pack. Therefore, it is necessary to meet the condition V(1) / Q(1)≥1.8 to ensure that even if the area of ​​the explosion-proof valve 111 is small, resulting in a limited flow of high-temperature and high-pressure fluid, the exhaust chamber 23 can still relieve pressure in time, thereby avoiding excessive pressure buildup inside the exhaust chamber 23 due to poor exhaust, and further improving the working safety of the battery pack in this embodiment.

[0125] In a specific embodiment, the area S(3) mm² of the set surface of the battery cell 11 ranges from 3000 mm² to 36000 mm², and specific values ​​such as 3000 mm², 6700 mm², 10400 mm², 14100 mm², 17800 mm², 21500 mm², 25200 mm², 28900 mm², 32600 mm², and 36000 mm² can be selected; the area S(2) mm² of the region enclosed by the explosion-proof valve 111 ranges from 50 mm² to 1500 mm², and specific values ​​such as 50 mm², 200 mm², 350 mm², 500 mm², 650 mm², 800 mm², 950 mm², 1100 mm², 1300 mm², and 1500 mm² can be selected, and S(2) / S (3) Specific values ​​such as 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18, and 0.2 can be selected, or other reasonable specific values ​​can be selected within the above range. Specific values ​​such as 1.8, 2.2, 2.6, 3.0, 3.4, 3.8, 4.2, 4.6, 5.0, and 5.29 can be selected, and no restrictions are imposed here.

[0126] like Figure 8 As shown, in one embodiment of this application, a groove 112 is formed on the explosion-proof valve 111; the groove 112 is disposed on the inner surface of the explosion-proof valve 111 near the battery cell; since the groove 112 is formed on the explosion-proof valve 111, the thickness of the groove 112 is small, and when the explosion-proof valve 111 breaks, it will break along the groove 112, thereby forming an opening for high-temperature and high-pressure fluid substances to be ejected.

[0127] When a groove 112 is formed on the explosion-proof valve 111 and the groove 112 is disposed on the inner surface of the explosion-proof valve 111, when Q(1)L≤60L, the amount of gas generated by a single battery cell 11 during thermal runaway can be limited, thereby ensuring that the pressure relief efficiency of the battery pack in this application embodiment can meet the requirements while ensuring that the battery pack in this application embodiment has sufficient structural strength.

[0128] like Figure 9 As shown, in one embodiment of this application, a groove 112 is formed on the explosion-proof valve 111; the groove 112 is disposed on the outer surface of the explosion-proof valve 111 away from the battery cell. As mentioned above, since the groove 112 is formed on the explosion-proof valve 111, the thickness of the groove 112 is small, and when the explosion-proof valve 111 breaks, it will break along the groove 112, thereby forming an opening for high-temperature and high-pressure fluid substances to be ejected.

[0129] Compared to the case where the groove 112 is provided on the inner surface of the explosion-proof valve 111, the groove 112 is more likely to break when it is provided on the outer surface of the explosion-proof valve 111. Therefore, when the groove 112 is formed on the explosion-proof valve 111 and the groove 112 is provided on the outer surface of the explosion-proof valve 111, when V(1)L≥12L, the volume of the exhaust chamber can be increased to further ensure that the pressure relief efficiency of the battery pack in this application embodiment meets the requirements, while ensuring that the battery pack in this application embodiment has sufficient structural strength.

[0130] In one embodiment of this application, the gas production Q(1)L of a single battery cell 11 during thermal runaway satisfies 3 L ≤ Q(1)L ≤ 60 L. When the gas production Q(1)L of a single battery cell 11 during thermal runaway satisfies 3 L ≤ Q(1)L ≤ 60 L, the pressure relief effect of the battery pack in this embodiment is guaranteed, and the working efficiency of the battery cells 11 in the battery pack is also guaranteed. In a specific embodiment, Q(1)L ranges from 3L to 60L, and specific values ​​such as 3L, 10L, 16L, 22L, 28L, 34L, 40L, 46L, 53L, and 60L can be selected. Other reasonable specific values ​​within the above range can also be selected, and no limitation is imposed here.

[0131] In one embodiment of this application, the volume V(1)L of the exhaust chamber 23 satisfies 5L≤V(1)L≤70L. When the volume V(1)L of the exhaust chamber 23 satisfies 5L≤V(1)L≤70L, it can be ensured that the pressure relief efficiency of the battery pack in this embodiment meets the requirements while also ensuring that the battery pack in this embodiment has sufficient structural strength. In a specific embodiment, V(1)L ranges from 5L to 70L, and specific values ​​such as 5L, 12L, 20L, 28L, 35L, 43L, 50L, 58L, 64L, and 70L can be selected, or other reasonable specific values ​​can be selected within the above range, without limitation.

[0132] like Figure 4 As shown, in one embodiment of this application, the extension length of the battery cell 11 in the first direction is less than the extension length in the second direction. The extension length D(3)mm of the battery cell 11 in the first direction is ≤30mm, and the first direction, the second direction and the height direction of the battery cell 11 are all perpendicular to each other. The first direction is the width direction of the battery cell setting surface; V(1) / Q(1) satisfies 1.11≤V(1) / Q(1)≤5.

[0133] It is understandable that when the extension length of the battery cell 11 in the first direction is less than the extension length in the second direction, and the first direction, the second direction and the height direction of the battery cell 11 are all perpendicular to each other, the width direction of the battery cell 11 is the first direction, the length direction is the second direction, and the extension length D(3) mm of the battery cell 11 in the first direction is the thickness of the battery cell 11. When the thickness of the battery cell 11 is less than or equal to 30 mm, the gas generation process of the battery cell 11 after thermal runaway is usually less severe.

[0134] Therefore, the extension length D(3)mm ≤ 30mm of the battery cell 11 in the first direction, and V(1) / Q(1) satisfy 1.11 ≤ V(1) / Q(1) ≤ 5, can further reduce the required volume of the exhaust chamber 23, thereby further improving the overall structural rigidity and deformation resistance of the battery pack in this embodiment, and ensuring that the battery pack has good thermal safety and structural reliability. In a specific embodiment, D(3)mm ≤ 30mm can be selected from specific values ​​such as 3mm, 6mm, 9mm, 12mm, 15mm, 18mm, 21mm, 24mm, 30mm, or other reasonable specific values ​​within the above range. The range of V(1) / Q(1) is from 1.11 to 5, and specific values ​​such as 1.11, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.3, 4.7, 5, or other reasonable specific values ​​within the above range can be selected, without limitation.

[0135] In another embodiment of this application, the range of D (3) mm is 30 mm to 60 mm. Specific values ​​such as 30 mm, 33 mm, 36 mm, 39 mm, 42 mm, 45 mm, 48 mm, 51 mm, 55 mm, and 60 mm can be selected. Other reasonable specific values ​​can also be selected within the above range, and no restrictions are imposed here.

[0136] Specifically, in one embodiment of this application, the height of the battery cell 11 ranges from 70 mm to 250 mm, and is more preferably from 70 mm to 150 mm, and the length of the battery cell 11 ranges from 140 mm to 320 mm.

[0137] In one embodiment of this application, the extension length of the battery cell 11 in the first direction is less than the extension length in the second direction. The extension length D(3)mm of the battery cell 11 in the first direction is greater than or equal to 60mm. The first direction, the second direction and the height direction of the battery cell 11 are all perpendicular to each other. The first direction is the width direction of the set surface of the battery cell 11, and 10L≤V(1)L≤70L.

[0138] When the extension length D(3)mm of the battery cell 11 in the first direction is ≥60mm and 10L≤V(1)L≤70L, the exhaust rate of the battery pack in this embodiment can be further improved by increasing the volume of the exhaust chamber 23. In a specific embodiment, D(3)mm can be selected from specific values ​​such as 60mm, 75mm, 90mm, 105mm, 120mm, 135mm, 150mm, 165mm, 180mm, 200mm, etc., or other reasonable specific values ​​can be selected within the above range, without limitation. In one embodiment of this application, the positive electrode active material of the battery cell 11 includes lithium nickel cobalt manganese oxide; and the volumetric energy density of the battery pack is greater than 300Wh / L; V(1) / Q(1) satisfies 1.5≤V(1) / Q(1)≤5.29.

[0139] It is understandable that lithium nickel cobalt manganese oxide (NCM) is a common cathode material system for lithium-ion batteries. When the cathode active material of the battery cell 11 includes lithium nickel cobalt manganese oxide and the volumetric energy density of the battery pack is greater than 300Wh / L, the gas generation process of the battery cell 11 after thermal runaway is relatively more intense, with not only a faster gas generation rate but also a potentially larger gas generation amount.

[0140] Therefore, when the positive electrode active material of the battery cell 11 includes lithium nickel cobalt manganese oxide; and the volumetric energy density of the battery pack is greater than 300Wh / L; and V(1) / Q(1) satisfies 1.5≤V(1) / Q(1)≤5.29, the pressure relief performance of the battery pack in this embodiment can be further improved, effectively reserving a safety margin, and more effectively preventing pressure runaway and heat propagation caused by low exhaust efficiency, thereby improving the safety protection level of high-energy-density battery packs such as ternary lithium under extreme conditions. It is understood that the molar percentage of nickel in lithium nickel cobalt manganese oxide ranges from 40% to 90%, and the compressive density ranges from 3.0 to 3.8 g / cm³. 3 Under these conditions, the volumetric energy density of the battery pack can be effectively improved, ensuring that the volumetric energy density of the battery pack is greater than 300 Wh / L. In one embodiment of this application, the upper limit of the volumetric energy density of the battery pack is 950 Wh / L.

[0141] In a specific embodiment, the volumetric energy density of the battery pack can be selected from specific values ​​such as 300Wh / L, 370Wh / L, 440Wh / L, 510Wh / L, 580Wh / L, 650Wh / L, and 720Wh / L, or other reasonable specific values ​​within the above range, without limitation; the range of V(1) / Q(1) is 1.5 to 5.29, and specific values ​​such as 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.4, 4.8, 5.1, and 5.29 can be selected, or other reasonable specific values ​​within the above range, without limitation.

[0142] The test method for the energy density of the battery pack is as follows: Measure the maximum length l, maximum width d, and maximum thickness h of the battery cell. Calculate the volume of a single cell using the formula V = l × d × h, in liters (L). Place the battery cell in a 25°C chamber and perform the following operations: charge at 0.33C to the upper limit voltage, then charge at a constant voltage to the cutoff current of 0.05C; let stand for 30 minutes, then discharge at 0.33C to the lower limit voltage; repeat the above operation 3 times. Take the discharge capacity of the third cycle as the battery's fixed capacity, denoted as W, in Ah. Calculate the volumetric energy density of the battery cell using the formula volumetric energy density = (W × N) / V, in Wh / L, where N is the average operating voltage of the battery cell.

[0143] If the cathode material is lithium nickel cobalt manganese oxide, the upper limit voltage is 4.25V, the lower limit voltage is 2.5V, and the average operating voltage is 3.7V. If the cathode material is lithium iron phosphate, the upper limit voltage is 3.65V, the lower limit voltage is 2.5V, and the average operating voltage is 3.3V.

[0144] In another embodiment of this application, the positive electrode active material of the battery cell 11 includes lithium iron phosphate; V(1) / Q(1) satisfies 1.11≤ V(1) / Q(1) ≤4.92.

[0145] Understandably, lithium iron phosphate (LFP) is also a common cathode material system for lithium-ion batteries, and its general chemical formula can be LiFe. 1-x M x PO y Q zWherein, 0≤x≤0.1, 3.85≤y<4, 0≤z≤0.05, and the doping element M includes, but is not limited to, one or more of Mn, Ni, Co, Cr, Cu, Bi, and Sb, and the doping element Q includes, but is not limited to, one or more of F, N, and Cl. When the positive electrode active material of the battery cell 11 includes lithium iron phosphate, the gas generation process of the battery cell 11 after thermal runaway is relatively mild, typically with a relatively small total gas generation and a relatively low degree of reaction intensity.

[0146] Therefore, when the positive electrode active material of the battery cell 11 includes lithium iron phosphate, V(1) / Q(1) satisfies 1.11≤ V(1) / Q(1) ≤4.92, which can reduce the space occupied by the exhaust chamber 23 in the housing 20 while meeting the exhaust requirements of the lithium iron phosphate battery pack, and effectively improve the energy density and structural strength of the battery pack in this embodiment.

[0147] In a specific embodiment, V(1) / Q(1) ranges from 1.11 to 4.92. Specific values ​​such as 1.11, 1.5, 2.0, 2.4, 2.9, 3.3, 3.7, 4.1, 4.5, and 4.92 can be selected, or other reasonable specific values ​​can be selected within the above range. No restrictions are imposed here.

[0148] In another embodiment of this application, the volumetric energy density of the battery pack can be less than 300Wh / L, and specific values ​​such as 10Wh / L, 40Wh / L, 70Wh / L, 100Wh / L, 130Wh / L, 160Wh / L, 190Wh / L, 220Wh / L, 260Wh / L, and 300Wh / L can be selected. Other reasonable specific values ​​can also be selected within the above range, and no restrictions are imposed here.

[0149] In one embodiment of this application, the battery cell 11 includes a positive electrode and a negative electrode; the positive electrode includes a positive current collector and a positive active material layer coated on the surface of the positive current collector, the ratio of the thickness of the positive active material layer to the thickness of the positive current collector is in the range of 0.625 to 0.972; the negative electrode includes a negative current collector and a negative active material layer coated on the surface of the negative current collector, the ratio of the thickness of the negative active material layer to the thickness of the negative current collector is in the range of 0.714 to 0.98.

[0150] Specifically, the thickness of the positive electrode active material layer ranges from 30 μm to 210 μm, the thickness of the positive electrode current collector ranges from 6 μm to 18 μm, the thickness of the negative electrode active material layer ranges from 30 μm to 200 μm, and the thickness of the positive electrode current collector ranges from 4 μm to 12 μm. When the positive electrode active material includes lithium nickel cobalt manganese oxide, the thickness of the positive electrode active material layer can range from 30 μm to 150 μm, and when the negative electrode active material includes graphite, the thickness of the negative electrode active material layer can range from 36 μm to 180 μm.

[0151] In a specific embodiment, the ratio of the thickness of the positive electrode active material layer to the thickness of the positive electrode current collector ranges from 0.625 to 0.972, and specific values ​​such as 0.625, 0.67, 0.72, 0.77, 0.82, 0.87, 0.90, 0.93, 0.95, and 0.972 can be selected, or other reasonable specific values ​​can be selected within the above range. The ratio of the thickness of the negative electrode active material layer to the thickness of the negative electrode current collector ranges from 0.714 to 0.98, and specific values ​​such as 0.714, 0.75, 0.79, 0.83, 0.87, 0.90, 0.93, 0.95, 0.96, and 0.98 can be selected, or other reasonable specific values ​​can be selected within the above range. The thickness of the positive electrode active material layer ranges from 30 μm. The thickness of the positive electrode current collector ranges from 6 μm to 210 μm, with specific values ​​such as 30 μm, 50 μm, 70 μm, 90 μm, 110 μm, 130 μm, 150 μm, 170 μm, 190 μm, and 210 μm available, or other reasonable values ​​within the above ranges. The thickness of the negative electrode active material layer ranges from 30 μm to 200 μm, with specific values ​​such as 30 μm, 48 μm, 66 μm, 84 μm, 102 μm, 120 μm, 138 μm, 156 μm, 178 μm, and 200 μm available. Specific values ​​can be selected from the above range, such as 4μm to 12μm, including 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 10.5μm, 11μm, and 12μm. Other reasonable values ​​can also be selected from the above range. When the positive electrode active material includes lithium nickel cobalt manganese oxide, the thickness of the positive electrode active material layer ranges from 30μm to 150μm, including 30μm, 42μm, 56μm, 70μm, 84μm, 98μm, 112μm, 126μm, 138μm, and 150μm. Other reasonable values ​​can also be selected from the above range. When the negative electrode active material includes graphite, the thickness of the negative electrode active material layer ranges from 36μm. Up to 180μm, specific values ​​such as 36μm, 50μm, 64μm, 78μm, 92μm, 106μm, 120μm, 134μm, 155μm, and 180μm can be selected, or other reasonable specific values ​​can be selected within the above range, without any restrictions.

[0152] In one embodiment of this application, the areal density of the positive electrode active material layer ranges from 96 g / m² to 292 g / m²; and / or the areal density of the negative electrode active material layer ranges from 36 g / m² to 180 g / m².

[0153] The testing methods for the density of the positive electrode active material layer and the negative electrode active material layer are as follows: 1. Pretreatment: Battery cell 11 is discharged at 0.33C to the lower limit voltage. Based on the specific system, the lower limit voltage is determined, where LFP, NCM, and LMFP are -2.5V; lithium nickel manganese oxide is -3.5V. The electrode sheets are disassembled and soaked in dimethyl carbonate (DMC) solution for 4 hours; then dried at 60℃ for 24 hours. 2. Use a punching machine to punch the pretreated electrode into circular pieces of a fixed area, denoted as S0 mm². Take three circular pieces as parallel samples, and weigh each of the three circular pieces using an electronic balance. Take the average value and record it as M1 g. Add an appropriate amount of deionized water to each of the three circular pieces, and gently wipe off the coating on the circular pieces with lint-free paper to expose the current collector. Let them stand at room temperature or dry for 10 minutes. After the current collector is dry, weigh each of the three current collectors and take the average value and record it as M0 g. Calculate the surface density of the electrode using the following formula: M1 - M0 / S0.

[0154] In one embodiment of this application, the battery cell 11 further includes an electrolyte disposed inside the casing. The electrolyte includes a lithium salt, specifically lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI), with the molar concentration of LiFSI being 0.2 mol / L to 2.0 mol / L. Since lithium hexafluorophosphate produces a relatively large amount of gas at room temperature, the amount of LiFSI can be appropriately increased to reduce the amount of gas produced by the battery cell 11 at room temperature. Simultaneously, because LiFSI produces gas at higher temperatures at relatively fast rates, limiting the amount of LiFSI can reduce the amount of gas produced by the battery cell 11 at high temperatures.

[0155] In a specific embodiment, the molar concentration of lithium bis(fluorosulfonyl)imide ranges from 0.2 mol / L to 2.0 mol / L. Specific values ​​such as 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, and 2.0 mol / L can be selected, or other reasonable specific values ​​can be selected within the above range. No restrictions are imposed here.

[0156] The content test methods for lithium hexafluorophosphate and lithium difluorosulfonylimide are as follows: 1) Electrolyte Collection: If the electrolyte of the test object is in a secondary battery, use a battery charge / discharge device to discharge the secondary battery under test. Discharge conditions: current 0.3C, cutoff lower limit voltage (determine the lower limit voltage based on the specific system, where LFP, LMFP - 2.5V, NCM - 2.8V, lithium nickel manganese oxide - 3.5V). After recording the battery number / barcode, disassemble the battery in a glove box (H2O ≤ 0.1ppm, O2 ≤ 0.1ppm) to collect the electrolyte. There are three methods for collecting the electrolyte: After removing the battery cover, ① if there is free electrolyte, use a pipette to collect the electrolyte into a 5mL sample tube and seal it with sealing tape to prevent electrolyte leakage. ② if there is no free electrolyte, use a hydraulic press (Beijing Heng'ao Technology Co., Ltd.'s FY-30 hydraulic press) to continuously pressurize until free electrolyte appears, collect the electrolyte into a sample tube and seal it. ③ Add an appropriate amount of dichloromethane extractant to the battery and record the dichloromethane content. After adding dichloromethane, put the battery into an aluminum-plastic bag and seal it with a heat sealer. Transfer it to an ultrasonic oscillator and oscillate for 12 hours to allow the electrolyte in the electrode to mix thoroughly with the dichloromethane. Then, use a pipette to draw the mixture of dichloromethane and electrolyte into a 5mL sample tube and seal the sample tube with sealing glue. If the electrolyte of the test object is a finished product, the component content can be determined directly by comparing the standard GC-MS spectrum, without the need for electrolyte collection.

[0157] 2) After filtering out solid suspended matter from the collected electrolyte sample, transfer 0.2 g of the above organic solution to a centrifuge tube containing approximately 19.8 g of ultrapure water. Shake vigorously to ensure the lithium salt (e.g., LiPF6) reacts fully with the water, dissociating the anion to be tested (e.g., F). - The sample solution was filtered using an aqueous syringe filter (0.22 or 0.45 μm pore size), placed in an IC-specific sample vial, and tested using an IC to obtain an IC spectrum. The obtained IC spectrum was compared with the standard spectrum in the IC database (the IC database contains spectra of all ionic substances) to confirm the type of lithium salt (the matching degree between the standard curve and the sample curve of the electrolyte to be tested is ≥98%). Then, the molar concentration of the corresponding lithium salt / inorganic salt additive was determined based on the peak area of ​​the anion to be tested in the electrolyte to be tested.

[0158] In one embodiment of this application, the battery cell 11 is a stacked cell; compared with the wound cell, the stacked cell can increase the exhaust rate of the battery cell 11, reduce the internal heat accumulation of the battery cell 11, and reduce the risk of thermal runaway of the battery cell 11.

[0159] Specifically, a laminated battery cell is a battery cell made by laminating positive electrode plates, negative electrode plates, and separators using a lamination process. The positive and negative electrode plates are separated by a separator, and adjacent positive and / or negative electrode plates within the battery cell are discontinuous. A wound battery cell is generally a battery cell made by winding continuous positive and negative electrode plates and separators using a winding process. The separator is located between adjacent positive and negative electrode plates.

[0160] like Figure 10 As shown, in one embodiment of this application, the housing 20 includes a frame 25 and a main pressure relief valve 26. The frame 25 includes a first wall 251 on the side closer to the battery pack 10 and a second wall 252 on the side farther from the battery pack 10. A through hole 211 is provided on the second wall 252. The main pressure relief valve 26 passes through the through hole 211 at least partially and is fixed to the second wall 252. The main pressure relief valve 26 is connected to the explosion-proof valve 111 of the battery cell 11 through the exhaust chamber 23. The high-temperature and high-pressure fluid material ejected from the explosion-proof valve 111 of the battery cell 11 can flow along the connecting channel penetrating the first plate 21 to the exhaust chamber 23, and then flow along the exhaust chamber 23 to the outside through the main pressure relief valve 26, effectively improving the safety performance of the battery pack. In one embodiment of this application, the opening area of ​​the main pressure relief valve 26 during pressure relief ranges from 800 mm² to 4300 mm², which effectively ensures the pressure relief performance of the main pressure relief valve 26, prevents high-temperature and high-pressure fluid substances from spreading inside the battery pack after being ejected from the explosion-proof valve 111, significantly reduces the risk of high-temperature ejected substances directly heating adjacent battery cells 11 or other electrical connections inside the housing 20, reduces the impact of thermal runaway of a single battery pack, and improves the thermal safety isolation performance of the battery pack. In a specific embodiment, the opening area of ​​the main pressure relief valve 26 during pressure relief ranges from 800 mm² to 4300 mm², and specific values ​​such as 800 mm², 1200 mm², 1600 mm², 2000 mm², 2400 mm², 2800 mm², 3200 mm², 3600 mm², 4000 mm², and 4300 mm² can be selected, or other reasonable specific values ​​can be selected within the above range, without limitation.

[0161] like Figure 10As shown, in one embodiment of this application, the distance between the main pressure relief valve 26 and the first plate 21 in the direction perpendicular to the first plate 21 is H(3) mm, where 8 ≤ H(3) ≤ 40. Since the distance between the main pressure relief valve 26 and the first plate 21 in the direction perpendicular to the first plate 21 is H3 mm, where 8 ≤ H(3) ≤ 40, it can effectively avoid the main pressure relief valve 26 being too high, leading to difficulty in venting and inability to release pressure in time, which could cause thermal runaway of other batteries. It can also avoid the main pressure relief valve 26 and the first plate 21 being at the same height, reducing the risk of deformation of the first plate 21, and also preventing structural failure after deformation of the main pressure relief valve 26. In a specific embodiment, the distance H(3) mm between the main pressure relief valve 26 and the first plate 21 is in the range of 8 to 40 mm. Specific values ​​such as 8 mm, 11 mm, 14 mm, 17 mm, 20 mm, 23 mm, 26 mm, 30 mm, 35 mm, and 40 mm can be selected. Other reasonable specific values ​​can also be selected within the above range, and no restrictions are imposed here.

[0162] This application provides a battery device that can serve as an operating power source or a driving power source for an electrical device, replacing or partially replacing fuel or natural gas to provide driving power for a vehicle 92. The electrical device encompasses a wide range of technical fields, including energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace.

[0163] The following example uses vehicle 92 as a specific example of an electrical device. Vehicle 92 can be a new energy vehicle, encompassing various types such as pure electric vehicles, hybrid electric vehicles, and range-extended electric vehicles. The battery pack can be located at the bottom, front, or rear of vehicle 92, providing electrical support, for example, acting as the vehicle 92's operating power source. Furthermore, vehicle 92 typically includes a controller 93, which manages the battery discharge process to cover various electrical needs during vehicle 92 startup, navigation, and driving.

[0164] In some embodiments, the battery device comprises one or more battery packs 91, which can be connected in series, parallel, or a hybrid configuration. A hybrid configuration refers to the simultaneous presence of series and parallel connections in the connection of multiple battery packs 91. In other embodiments, the battery device is a cluster-level battery architecture composed of multiple battery packs 91 connected in series, wherein the number of battery packs 91 in each cluster is strictly configured according to voltage and capacity requirements. More specifically, the battery unit of the battery device includes multiple batteries, some of which are connected in series to form a cluster that meets a preset power supply voltage requirement, and at least one spare battery among the multiple batteries is bypassed.

[0165] like Figure 11As shown, the battery pack 91 is disposed inside the electric vehicle and can be installed at the bottom, front, or rear of the electric vehicle. The battery pack 91 can provide power to the electric vehicle, such as acting as the operating power source for the electric vehicle. The electric vehicle may also be equipped with a controller 93 and a motor. The controller 93 is used to schedule the supply of electrical energy from the battery pack 91 to the motor to meet the power needs of the electric vehicle during starting, navigation, and driving.

[0166] The battery pack 91, as a rechargeable battery, is the power source for new energy vehicles. The battery pack 91 includes a housing and multiple battery cells housed within it. The housing provides space for the battery cells and other components, while also providing dustproof, waterproof, and protective functions to reduce the adverse effects of external liquids or foreign objects on the effectiveness and performance of the battery cells and other components, effectively extending the lifespan of the battery pack 91. The shape of the housing is not limited; for example, it can be a cuboid or cylinder. The material of the housing can also be flexibly selected, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic.

[0167] The battery pack 91 in this embodiment includes multiple battery groups, with one battery group disposed in each sub-accommodating space. Each battery group includes multiple stacked battery cells, and the stacking direction of the battery cells can be parallel to the plane of the base plate. The battery pack 91 also includes a battery management system (BMS), a thermal management system, an electrical connection system, high-voltage / low-voltage connectors, wiring harnesses, structural components such as housings and brackets, and protective components. These components are placed inside a housing and sealed by a top plate, forming a complete functional unit that can directly output electrical energy.

[0168] This application embodiment also provides an electrical device, which includes the aforementioned battery pack 91. It is understood that this electrical device can be various electrical devices such as energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, and electric vehicles. The aforementioned battery pack 91 can serve as the operating power source for the electrical device, or as the driving power source for the electrical device, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 92. It is applicable to numerous fields such as civilian use, military equipment, and aerospace, and is not limited thereto.

[0169] It should be noted that the elements described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this application will not describe the various possible combinations separately.

[0170] It should be understood that multiple components and / or parts can be provided by a single integrated component or part. Alternatively, a single integrated component or part can be divided into multiple separate components and / or parts. The use of the public designation "a" or "an" to describe a component or part does not exclude other components or parts.

[0171] It should be understood that while terms such as "first" or "second" may be used in this application to describe various elements, these elements are not limited by these terms; these terms are merely used to distinguish one element from another. The terminology used in one or more embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of one or more embodiments of this application. The singular forms "a," "the," and "the" as used in one or more embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used in one or more embodiments of this application refers to and includes any or all possible combinations of one or more associated listed items.

[0172] In this document, terms such as "upper," "lower," "front," "back," "left," and "right" are used only to indicate the relative positional relationship between related parts, and not to limit the absolute position of these related parts. In this document, terms such as "equal" and "same" are not strict mathematical and / or geometric limitations, but also include errors that are understandable to those skilled in the art and permissible in manufacturing or use. Unless otherwise stated, the numerical ranges in this document include not only the entire range within its two endpoints, but also several sub-ranges contained therein. The basic principles of this application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of the various embodiments of this application. Furthermore, the specific details disclosed above are only for illustrative and facilitative purposes, and are not limitations. The above details do not limit the application to the necessity of adopting the above specific details for implementation.

[0173] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A battery pack, characterized in that, include: The battery pack (10) includes at least one battery cell (11), the battery cell (11) includes a housing and a cell disposed inside the housing, the housing is provided with an explosion-proof valve (111) on the set surface, the explosion-proof valve includes a weak part, the thickness of the weak part is less than the thickness of the set surface, and the gas production of a single battery cell (11) during thermal runaway is Q(1) L; The enclosure (20) is configured to accommodate the battery pack (10), and the enclosure (20) is provided with an exhaust chamber (23) corresponding to and connected to the explosion-proof valve (111). The volume of the exhaust chamber (23) is V(1)L, and V(1) / Q(1) satisfies 1.11≤V(1) / Q(1)≤5.29; The housing (20) includes a first plate (21) fixedly connected to the setting surface of the battery pack (10) and a second plate (22) spaced apart from the first plate (21). The first plate (21) is disposed between the setting surface and the second plate (22). The first plate (21) and the second plate (22) are parallel to the setting surface of the battery pack. The exhaust chamber (23) is formed between the first plate (21) and the second plate (22). The exhaust chamber (23) is connected to the explosion-proof valve (111) through a connecting channel penetrating the first plate (21).

2. The battery pack according to claim 1, characterized in that, The orthographic projection of the explosion-proof valve (111) on the first plate (21) is at least partially aligned with the orthographic projection of the connecting channel on the first plate (21).

3. The battery pack according to claim 2, characterized in that, The explosion-proof valve (111) falls completely within the orthographic projection of the connecting channel onto the first plate (21).

4. The battery pack according to claim 1, characterized in that, The set surface of the battery cell (11) is the top surface of the battery cell (11), and the first plate (21), the second plate (22) and the exhaust chamber (23) are all located above the battery cell (11). Along the direction perpendicular to the set surface, the extension height of the exhaust chamber (23) is H(1) mm, where H(1) mm satisfies 8mm≤H(1) mm≤20mm.

5. The battery pack according to claim 2, characterized in that, The set surface of the battery cell (11) is the bottom surface of the battery cell (11), and the first plate (21), the second plate (22) and the exhaust chamber (23) are all located below the battery cell (11); Along the direction perpendicular to the set surface, the extension height of the exhaust chamber (23) is H(2) mm, where H(2) mm satisfies 8mm≤H(2) mm≤18mm.

6. The battery pack according to claim 1, characterized in that, The orthographic projection of a single exhaust chamber (23) on the first plate (21) and the orthographic projection of the explosion-proof valve (111) of at least two adjacent battery cells (11) on the first plate (21) are at least partially overlapped.

7. The battery pack according to claim 6, characterized in that, V(1) / Q(1)≥2.

8. The battery pack according to claim 6, characterized in that, The first plate (21) is provided with a through hole (211) that is connected to the explosion-proof valve (111) of the battery cell (11).

9. The battery pack according to claim 8, characterized in that, The battery pack (10) includes at least two battery cells (11) arranged along a set direction; the set direction is perpendicular to the length direction of the set surface of the battery cell (11), and along the set direction, the distance between the first plate (21) and the adjacent through hole (211) is D(2) mm, which satisfies 8mm≤D(2)mm≤50mm.

10. The battery pack according to claim 8, characterized in that, The area S(1)mm² of the through hole (211) is greater than the area S(2)mm² of the region enclosed by the corresponding explosion-proof valve (111).

11. The battery pack according to claim 1, characterized in that, The housing (20) is provided with at least two exhaust chambers (23), and the exhaust chambers (23) are respectively connected to at least one of the explosion-proof valves (111); The exhaust chambers (23) are configured to be isolated from each other by means of a separator (24), and the distance between adjacent exhaust chambers (23) is D(1) mm, where D(1) mm satisfies 5mm≤D(1) mm≤30mm.

12. The battery pack according to claim 11, characterized in that, The height of the separator (24) in the exhaust chamber (23) is less than the height of the exhaust chamber.

13. The battery pack according to claim 11, characterized in that, The housing (20) is provided with at least two of the separators (24), and at least some of the separators (24) are spaced apart along the stacking direction of the battery cells (11).

14. The battery pack according to claim 13, characterized in that, Along the stacking direction of the battery cells (11), the spacing between adjacent separators (24) is less than the extension length of a single battery cell (11) in the stacking direction of the battery cells (11); 3L≤Q (1)L≤55L.

15. The battery pack according to any one of claims 1 to 14, characterized in that, The ratio of the area S(2) mm² of the region enclosed by the explosion-proof valve (111) to the area S(3) mm² of the set surface of the battery cell (11) is S(2) / S(3)≤0.2, and V(1) / Q(1)≥1.

8.

16. The battery pack according to any one of claims 1 to 14, characterized in that, A groove (112) is formed on the explosion-proof valve (111); the groove (112) is located on the inner surface of the explosion-proof valve (111) near the battery cell; Q(1)L≤60L.

17. The battery pack according to any one of claims 1 to 14, characterized in that, A groove (112) is formed on the explosion-proof valve (111); the groove (112) is located on the outer surface of the explosion-proof valve (111) away from the battery cell; V(1)L≥12L.

18. The battery pack according to any one of claims 1 to 14, characterized in that, 3 L≤Q(1) L≤60 L; And / or, 5 L≤V(1) L≤70 L.

19. The battery pack according to any one of claims 1 to 14, characterized in that, The extension length of the battery cell (11) in the first direction is less than the extension length in the second direction. The extension length D(3)mm of the battery cell (11) in the first direction is ≤30mm. The first direction, the second direction and the height direction of the battery cell (11) are all perpendicular to each other. The first direction is the width direction of the set surface of the battery cell (11). V(1) / Q(1) satisfies 1.11≤V(1) / Q(1)≤5.

20. The battery pack according to any one of claims 1 to 14, characterized in that, The extension length of the battery cell (11) in the first direction is less than the extension length in the second direction. The extension length D(3)mm of the battery cell (11) in the first direction is greater than or equal to 60mm. The first direction, the second direction and the height direction of the battery cell (11) are all perpendicular to each other. The first direction is the width direction of the set surface of the battery cell (11), and 10L≤V(1)L≤70L.

21. The battery pack according to any one of claims 1 to 14, characterized in that, The positive electrode active material of the battery cell (11) includes lithium nickel cobalt manganese oxide; and the volumetric energy density of the battery pack is greater than 300Wh / L; V(1) / Q(1) satisfies 1.5≤ V(1) / Q(1) ≤5.

29.

22. The battery pack according to any one of claims 1 to 14, characterized in that, The positive electrode active material of the battery cell (11) includes lithium iron phosphate; V(1) / Q(1) satisfies 1.11≤ V(1) / Q(1) ≤4.

92.

23. The battery pack according to any one of claims 1 to 14, characterized in that, The battery cell (11) includes a positive electrode and a negative electrode. The positive electrode sheet includes a positive current collector and a positive active material layer coated on the surface of the positive current collector, wherein the ratio of the thickness of the positive active material layer to the thickness of the positive current collector ranges from 0.625 to 0.

972. and / or; The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector. The ratio of the thickness of the negative electrode active material layer to the thickness of the negative electrode current collector ranges from 0.714 to 0.

98.

24. The battery pack according to claim 23, characterized in that, The areal density of the positive electrode active material layer ranges from 96 g / m² to 292 g / m². And / or; the areal density of the negative electrode active material layer ranges from 36 g / m² to 180 g / m².

25. The battery pack according to any one of claims 1 to 14, characterized in that, The battery cell (11) also includes an electrolyte disposed inside the casing, the electrolyte including lithium salt, the lithium salt including lithium hexafluorophosphate and lithium bisfluorosulfonylimide, the molar concentration of the lithium bisfluorosulfonylimide being 0.2 mol / L to 2.0 mol / L.

26. The battery pack according to any one of claims 1 to 14, characterized in that, The battery cell is a laminated battery cell.

27. The battery pack according to any one of claims 1 to 14, characterized in that, The housing (20) includes a frame (25) and a main pressure relief valve (26). The frame (25) includes a first wall (251) on the side close to the battery pack (10) and a second wall (252) on the side away from the battery pack (10). A through hole (211) is provided on the second wall (252). The main pressure relief valve (26) passes through the through hole (211) at least partially and is fixed on the second wall (252). The main pressure relief valve (26) is connected to the explosion-proof valve (111) of the battery cell (11) through the exhaust chamber (23).

28. The battery pack according to claim 27, characterized in that, In the direction perpendicular to the first plate (21), the distance between the main pressure relief valve (26) and the first plate (21) is H(3) mm, where 8 ≤ H(3) ≤ 40.

29. An electrical appliance, characterized in that, Includes the battery pack according to any one of claims 1 to 28.

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