Shell structure, battery and battery pack

Abstract

The invention relates to the technical field of new energy, and discloses a shell structure, a battery and a battery pack. A pressure release valve is arranged on the first wall surface of the shell structure, and the bursting pressure of the pressure release valve is a; the pressure release valve comprises a weak part, and the residual thickness ratio of the weak part is b; the ratio of the mass of the Ti element of the shell structure to the total mass of all the elements of the shell structure is c; wherein c is greater than or equal to 60%; and c * b * a is greater than or equal to 1.5 and less than or equal to 24. According to the shell structure provided by the invention, the light weight of the shell structure is realized by comprehensively controlling the relationship among a, b and c, so that the energy density of the battery is improved; and meanwhile, when the battery is in thermal runaway, the pressure release valve can be opened in time, internal heat is effectively discharged, and detonation of the shell is avoided, so that light weight and safety are both considered. When the formula value of c.b.a is lower than the lower limit, light weight of the shell structure is not facilitated, and when the formula value of c.b.a is higher than the upper limit, the opening pressure of the pressure release valve is too large, and heat cannot be discharged in time.

Description

Technical Field

[0001] The present invention relates to the field of new energy technologies, and in particular to a shell structure, a battery, and a battery pack. Background Art

[0002] In related technologies, battery casings are often made of steel to meet the requirements of high strength and safety. However, the high density of steel casings can easily increase the overall weight of the battery pack, which in turn can affect vehicle range and performance. Furthermore, in the event of thermal runaway, the high-strength casing prevents the smooth dissipation of internal heat, which can easily cause the casing to explode and cause accidents. Summary of the Invention

[0003] In view of this, the present invention provides a shell structure, a battery, and a battery pack to solve the problem of how to balance lightweight and smooth exhaust requirements during thermal runaway.

[0004] In a first aspect, the present invention provides a shell structure, the shell structure comprising a Ti element;

[0005] A pressure relief valve is provided on the first wall surface of the shell structure, and the bursting pressure of the pressure relief valve is a;

[0006] The pressure relief valve includes a weak portion, the residual thickness of the weak portion is b1, the thickness of the first wall is b2, and the residual thickness ratio of the weak portion is b, where b=b1 / b2;

[0007] The mass of the Ti element of the shell structure accounts for c of the total mass of all elements of the shell structure; wherein c ≥ 60%;

[0008] And it satisfies: 1.5≤c·b·a≤24.

[0009] Beneficial Effects: The shell structure provided by the embodiments of the present invention achieves lightweight shell structure by comprehensively controlling the relationship between a, b, and c, thereby improving the energy density of the battery. At the same time, it ensures that when the battery thermally runs away, the pressure relief valve can open in time to effectively discharge internal heat and prevent the shell from exploding, thus achieving a balance between lightweight and safety. When the formula value of c·b·a is lower than the lower limit, the battery is prone to abnormal explosion during normal charging and discharging. This is also detrimental to lightweight shell structure and can easily affect the energy density of the battery. When the formula value is higher than the upper limit, the pressure relief valve opening pressure is too high, which is not conducive to opening the pressure relief valve. Heat cannot be discharged in time, resulting in severe heat accumulation inside the battery, causing the shell to explode, posing a safety hazard.

[0010] In a second aspect, the present invention further provides a battery comprising:

[0011] and a shell structure as described above, wherein a cavity is formed inside the shell structure, and the cavity is suitable for accommodating the battery cell.

[0012] Since the battery includes a shell structure, it has the same effect as the shell structure and will not be described in detail here.

[0013] In a third aspect, the present invention further provides a battery pack comprising: a box body and a plurality of batteries as described above, wherein the box body comprises a bottom plate and a plurality of side plates, and the batteries are fixed to the bottom plate of the box body.

[0014] Because the battery pack includes a shell structure, it has the same effect as the shell structure and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 is a schematic diagram of the housing structure of the present invention;

[0017] Figure 2 A top view of the housing structure of the present invention;

[0018] Figure 3 A top view of another housing structure of the present invention;

[0019] Figure 4 for Figure 2 Partial schematic diagram of the AA section;

[0020] Figure 5 for Figure 4 Enlarged view of point B in the middle;

[0021] Figure 6 for Figure 4 Another enlarged view of point B in the middle;

[0022] Figure 7 for Figure 4 Another enlarged view of point B in the middle;

[0023] Figure 8 for Figure 4 Another enlarged view of point B in the middle;

[0024] Figure 9 A partially enlarged view of the first wall surface of the present invention;

[0025] Figure 10 Another partial enlarged view of the first wall of the present invention;

[0026] Figure 11This is another partial enlarged view of the first wall surface of the present invention;

[0027] Figure 12 This is another partial enlarged view of the first wall surface of the present invention;

[0028] Figure 13 A top view of another housing structure of the present invention;

[0029] Figure 14 Schematic diagram of the decomposition of the battery of the present invention;

[0030] Figure 15 Schematic diagram of the groove of the present invention.

[0031] Description of reference numerals:

[0032] 1. Housing structure; 10. Housing body; 11. First wall; 12. Compacted portion; 13. Recessed portion; 14. Cover plate; 15. Second wall; 2. Pressure relief valve; 21. Weak portion; 22. Valve plate; 23. First groove portion; 24. Second groove portion; 241. Second inner groove portion; 242. Second outer groove portion;

[0033] 3. Pole; 4. Cell; 41. Cell body; 42. Positive electrode tab; 43. Negative electrode tab;

[0034] 51. Opening; 52. Bottom wall; 53. Side wall; 54. Arc-shaped transition portion. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0038] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] In the prior art, battery casings are often made of steel to meet the requirements of high strength and high safety performance. However, the high density of steel casings can easily increase the overall weight of the battery pack, which in turn can easily affect the vehicle's range and performance.

[0040] The density of metallic Ti is significantly lower than that of steel. Under the same strength requirements, Ti components can be lighter than steel. Therefore, by adding a certain proportion of Ti to the shell, the shell weight can be reduced, the shell can be lightweighted, and the energy density of the battery can be increased. However, due to the high strength of Ti, when the battery thermally runs away, the heat and gas inside the high-strength shell need to break through the weak part, and the heat can be released after the weak part opens. If the strength of the weak part is too high, the heat and gas inside the shell are not enough to break the weak part open, and as the heat inside the shell continues to generate and accumulate, it is easy to cause instantaneous explosions, causing safety accidents. Therefore, how to reduce the weight of the shell, achieve lightweight shells, and increase the energy density of the battery; while taking into account the smooth exhaust of the high-strength shell when the battery thermally runs away, has become an urgent problem to be solved.

[0041] In order to better understand the technical solution of this application, first, the following is explained:

[0042] The battery in this application is a secondary battery, also known as a rechargeable battery or storage battery, which refers to a battery that can be recharged to activate the active material after the battery is discharged and continue to be used.

[0043] Typically, a secondary battery includes a cell, an electrolyte, and a housing. The cell includes a positive electrode, a negative electrode, and a separator. The cell and electrolyte are assembled in the housing. During the battery charge and discharge process, active ions (such as lithium ions) are embedded and released back and forth between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through. The electrolyte between the positive electrode and the negative electrode mainly plays the role of conducting active ions.

[0044] As an example, the preparation process of a secondary battery is as follows: stack the positive electrode sheet, separator, and negative electrode sheet in order, so that the separator is placed between the positive and negative electrode sheets to act as an isolate, and then wind or stack the sheets to obtain a battery cell; place the battery cell in a shell, dry it, and then inject the electrolyte, and obtain a secondary battery through vacuum packaging, standing, formation, shaping and other processes.

[0045] The positive electrode sheet, negative electrode sheet, electrolyte, and diaphragm are introduced in order as follows:

[0046] [Positive electrode]

[0047] The positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material, which can be any positive electrode active material disclosed in the prior art or a positive electrode active material optimized on the basis of the prior art.

[0048] The present application does not impose any particular restrictions on the type of positive electrode active material of the positive electrode sheet. As an example, the positive electrode active materials in the present application include lithium-containing transition metal oxides (e.g., LiCoO2), phosphides (e.g., LiFePO4), or lithium-intercalated compounds (e.g., lithium cobalt oxide, lithium nickel oxide, and other positive electrode materials for binary lithium batteries, or lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and other positive electrode materials for ternary lithium batteries).

[0049] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (for example, N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, rolling, cutting and other processes, the positive electrode sheet can be obtained.

[0050] In this application, the binder is used to improve the adhesion between the positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. This application does not particularly limit the type of binder for the positive electrode sheet. In this application, the binder can be a conventional choice in the battery field. Specifically, the binder can be at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polyimide (PI), polyacrylic acid (PAA), polyacrylate, polyolefin, sodium carboxymethyl cellulose (CMC), or sodium alginate.

[0051] The present application has no particular limitation on the positive electrode current collector, as long as it has conductivity and does not cause adverse chemical changes in the battery, and can use, for example: stainless steel, aluminum, nickel, titanium, fired carbon; or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium, silver, etc.

[0052] [Negative electrode]

[0053] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. The negative electrode active material layer includes a silicon-based material. The present application does not specifically limit the type of silicon-based material. The silicon-based material can be a silicon-carbon material and / or a silicon-oxygen material. As an example, the silicon-based material can be one or more of a silicon-carbon composite negative electrode material, a silicon monoxide negative electrode material, a modified silicon monoxide negative electrode material, and a nano-silicon material. The negative electrode active material in the negative electrode active material layer can also optionally include one or more of artificial graphite, natural graphite, and hard carbon.

[0054] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, rolling, cutting and other processes, the negative electrode sheet can be obtained.

[0055] The present application has no specific restrictions on the type of negative electrode conductive agent. In some embodiments, as an example, the negative electrode conductive agent can be one or more conventional negative electrode conductive agents such as acetylene black and carbon nanotubes. The present application has no specific restrictions on the type of negative electrode binder. In some embodiments, as an example, the binder can be one or more conventional negative electrode binders such as styrene-butadiene rubber latex (SBR), polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), sodium carboxymethyl cellulose (CMC), etc. In the present application, the binder is preferably PAA, SBR and CMC, and the mass ratio of PAA, SBR and CMC can be (34.38-74.29): (20-59.38): (5-7.14).

[0056] The present application has no specific limitation on the type of the negative electrode current collector. In some embodiments, as an example, the negative electrode current collector can be one of the conventional negative electrode current collectors such as copper foil.

[0057] [Electrolyte]

[0058] The electrolyte conducts ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and one may be selected based on needs. For example, the electrolyte of this application may be any electrolyte suitable for electrochemical energy storage devices in the art. The electrolyte includes an electrolyte and a solvent. The electrolyte may typically include a lithium salt, and additives may also be added to the electrolyte.

[0059] Specifically, the lithium salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bis(oxalatoborate) (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalatophosphate) (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP). The concentration of the electrolyte in the electrolyte solution may be 0.5 to 5 mol / L.

[0060] Specifically, the solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE).

[0061] In some embodiments, as examples, the additive may be conventional electrolyte additives such as fluoroethylene carbonate (FEC), chloroethylene carbonate (CEC), and vinylene carbonate (VC).

[0062] [Diaphragm]

[0063] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0064] In some embodiments, as an example, the diaphragm can be one of PP, PE, and PP / PF; the diaphragm can also be a structure in which a coating is provided on the surface of the base film, wherein the base film coating can be one of PP, PE, and PP / PF, and the coating is an inorganic coating and / or an organic coating, the inorganic coating can be selected from alumina ceramic layer, beryl, etc., and the organic coating can be selected from PVDF, etc.

[0065] The following combination Figures 1 to 14 , describing embodiments of the present invention.

[0066] According to an embodiment of the present invention, in one aspect, a shell structure 1 is provided, the shell structure 1 comprising a Ti element;

[0067] A pressure relief valve 2 is provided on the first wall surface 11 of the shell structure 1, and the bursting pressure of the pressure relief valve 2 is a;

[0068] The pressure relief valve 2 includes a weak portion 21 , the residual thickness of the weak portion 21 is b1 , the thickness of the first wall 11 is b2 , and the residual thickness ratio of the weak portion 21 is b, where b=b1 / b2;

[0069] The mass of the Ti element of the shell structure accounts for c of the total mass of all elements of the shell structure; wherein c ≥ 60%;

[0070] And it satisfies: 1.5≤c·b·a≤24.

[0071] The housing structure 1 of this embodiment is applied to a battery. Optionally, the battery can be a cylindrical battery or a quadrangular prism battery (not shown in the figure). The battery can be prepared in a wound form or a laminated form.

[0072] The pressure relief valve 2 is used to release the gas and heat inside the battery when thermal runaway occurs.

[0073] The casing structure 1 of this embodiment contains Ti, which helps achieve lightweight construction and thus improve the battery's energy density. However, due to the high strength of Ti, a larger c increases the overall strength of the casing structure 1, making heat dissipation more difficult during thermal runaway. This, in turn, increases the burst pressure a of the pressure relief valve 2. Heat accumulated within the battery cannot be smoothly discharged through the pressure relief valve 2, potentially causing battery explosions.

[0074] In this embodiment, the content of C is greater than or equal to 60%. As a further optional solution, the material of the shell structure can be pure titanium or a Ti alloy, such as titanium aluminum alloy, titanium aluminum zirconium alloy, titanium molybdenum alloy, etc.

[0075] When the material of the shell structure is pure titanium, it means that the content of C in the shell structure is greater than or equal to 99.95%.

[0076] The shell structure 1 provided in the embodiments of the present invention achieves lightweighting of the shell structure 1 by comprehensively controlling the relationship between a, b, and c, thereby improving the battery's energy density. At the same time, it ensures that the pressure relief valve 2 can open promptly in the event of thermal runaway, effectively discharging internal heat and preventing the shell from exploding, thus achieving a balance between lightweighting and safety. When the formula value of c·b·a is below the lower limit, the battery is prone to abnormal explosion during normal charging and discharging. This is also detrimental to lightweighting the shell structure and can easily affect the battery's energy density. When the formula value is above the upper limit, the pressure relief valve opening pressure is too high, hindering its opening, preventing timely heat dissipation, and causing severe heat accumulation within the battery, which can lead to explosions in the shell and pose a safety hazard.

[0077] By controlling the relationship between the three, the shell structure 1 effectively reduces the overall weight while maintaining high strength, achieving lightweight shell structure and improving the energy density of the battery. At the same time, it ensures that in the thermal runaway state, the pressure relief valve 2 responds quickly and discharges heat smoothly, significantly improving the battery safety performance and vehicle endurance.

[0078] Illustratively, in this embodiment, the value of c·b·a can be 1.5 or 2.17 or 2.26 or 2.36 or 2.42 or 2.67 or 2.85 or 3 or 3.12 or 3.54 or 4.18 or 4.35 or 5.3 or 6.4 or 8.8 or 9.5 or 10 or 12.3 or 13.8 or 15.2 or 16.9 or 18.7 or 20 or 21.2 or 23.7 or 24, etc., or it can be an interval range formed by any two of the above values.

[0079] In some embodiments, a satisfies: 1.3 MPa≤a≤2.6 MPa;

[0080] and / or, b satisfies: 0.01≤b≤0.1;

[0081] And / or, c satisfies: 60%≤c≤99.99%.

[0082] This embodiment further controls c within the range of 60% ≤ c ≤ 99.99%, thereby avoiding excessive casing strength due to an excessively high mass fraction of the Ti element. This ensures that pressure relief valve 2 opens promptly in the event of thermal runaway, effectively dissipating heat and preventing battery explosion, achieving a balance between lightweighting and safety. This also ensures that casing structure 1 possesses sufficient strength to prevent safety hazards caused by insufficient strength during normal use, while maintaining the lightweight nature of casing structure 1, improving the battery's energy density and preserving its lightweight advantages.

[0083] To ensure timely pressure relief at high temperatures, b is further controlled within the range of 0.01 ≤ b ≤ 0.1. This allows the gas to quickly open the weak portion 21 of the pressure relief valve 2 in the event of thermal runaway, allowing the hot gases to be discharged promptly. This also prevents the weak portion 21 from opening abnormally during normal battery operation. Precisely controlling the residual thickness ratio b of the weak portion 21 ensures a rapid response at high temperatures and stability under normal conditions.

[0084] Additionally, in order to ensure timely pressure relief under high temperature conditions, the bursting pressure a of the pressure relief valve 2 is appropriately reduced so that it can respond in a timely manner under high temperature conditions, ensuring that heat is quickly discharged and preventing the shell from exploding. At the same time, the bursting pressure a of the pressure relief valve 2 cannot be too low to avoid false triggering under normal working conditions, affecting battery safety, and ensuring the integrity of the weak portion 21 under normal working conditions.

[0085] Illustratively, in this embodiment, the value of a can be 1.3 MPa or 1.5 MPa or 1.8 MPa or 1.92 MPa or 2 MPa or 2.15 MPa or 2.23 MPa or 2.4 MPa or 2.6 MPa, etc., or it can be an interval range formed by any two of the above values.

[0086] Illustratively, in this embodiment, the value of b may be 0.01 or 0.03 or 0.04 or 0.05 or 0.07 or 0.1, etc., or may be an interval formed by any two of the above values.

[0087] Illustratively, in this embodiment, the value of c may be 60% or 70% or 75% or 80% or 85% or 88% or 92% or 99.99%, etc., or may be an interval formed by any two of the above values.

[0088] In conjunction with Table 1 below, through several examples and comparative examples, the provided batteries were subjected to weight loss rate tests and cycle performance tests to verify whether they were qualified.

[0089] Table 1

[0090]

[0091] Regarding the above table, the following are explained:

[0092] Performance 1: Weight Loss Test. Test method: Use a flat or rod-shaped heating device covered with a ceramic, metal, or insulating layer. Place the heating surface of the heating device in direct contact with the surface of the battery cell. Within 24 hours, activate the heating device and heat the triggering object at its maximum power. Temperature sensors are placed at the pressure relief valve port / on the large side of the battery. Calculate the mass of the battery cell before and after thermal runaway: m1 for the mass of the battery cell before thermal runaway and m2 for the mass of the battery cell after thermal runaway. Calculate the value (m1-m2) / m1. A value less than 40% is considered a failure, indicating that the material inside the housing has not erupted and the internal temperature is too high. A value greater than or equal to 40% is considered a pass, indicating that heat can be smoothly discharged through the pressure relief valve, preventing excessive internal heating. Thermal runaway triggering criteria include: a) a voltage drop at the triggering object exceeding 25% of the initial voltage; b) the temperature at the monitoring point reaches the manufacturer's specified maximum operating temperature; and c) the temperature rise rate dT / dt at the monitoring point is ≥ 1°C / s and persists for at least 3 seconds. When a) and c) or b) and c) occur, it is determined that thermal runaway occurs.

[0093] In the table above, the conclusions of the weight loss rate test include the following: whether the pressure relief valve can open normally during thermal runaway; and the specific numerical range of the weight loss rate.

[0094] Performance 2: Cycling performance test. Test method: At 25°C, the lithium-ion batteries prepared in the examples and comparative examples were subjected to a cycling test according to the following procedure:

[0095] 1) Charge at a constant current rate of 1C to the upper limit voltage, and then charge at a constant voltage until the current drops to 0.05C;

[0096] 2) Let it sit for 20 minutes;

[0097] 3) Discharge at a rate of 1C to the lower limit voltage;

[0098] 4) Let it sit for 20 minutes.

[0099] Perform a cycle test according to steps 1)-4) for 50 cycles. Observe whether the pressure relief valve flies out during the cycle. If the pressure relief valve flies out, it indicates that the battery is abnormally opened under working conditions and fails the test.

[0100] Among them, LiNi 0.9 Co 0.05 Mn 0.05 02 upper limit voltage 4.25V, lower limit voltage 2.5V; lithium iron phosphate upper limit voltage 3.65V, lower limit voltage 2.5V.

[0101] In the above table, the conclusions of the cycle performance test include the following: whether the battery is abnormally turned on when it is working.

[0102] It should be noted that the battery cell is composed of a positive electrode sheet, a negative electrode sheet and a separator disposed therebetween, which are stacked to form a battery cell body 41 .

[0103] Positive electrode sheet: includes a positive electrode current collector and a positive electrode active material. The positive electrode current collector can be made of metal materials such as aluminum foil, nickel foil, stainless steel, or a composite foil formed by a combination of metal and insulating materials. The positive electrode active material includes a positive electrode active main material, a conductive agent, an adhesive, etc. The positive electrode active main material includes one or more lithium-containing positive electrode active materials such as lithium iron phosphate, a ternary material containing nickel, cobalt and manganese, and lithium iron manganese phosphate;

[0104] Negative electrode sheet: includes negative electrode current collector and negative electrode active material. The negative electrode current collector can be made of metal materials such as copper foil, aluminum foil, stainless steel, or a composite foil formed by a combination of metal and insulating materials; the negative electrode active material includes negative electrode active main material, conductive agent, adhesive, etc. The negative electrode active main material includes one or more negative electrode active main materials such as artificial graphite, natural graphite, silicon carbon, silicon oxide, lithium titanate, etc.

[0105] The preparation of the battery includes the following steps:

[0106] (1) Preparation of positive electrode sheet:

[0107] The prepared positive electrode active material, conductive agent acetylene black, and binder PVDF are mixed, and the solvent NMP is added. The mixture is stirred in a vacuum mixer until the system is uniform to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on both surfaces of the positive electrode current collector aluminum foil, dried at room temperature, and then transferred to an oven for further drying. The positive electrode sheets are then cold pressed and cut into pieces. Specifically, the mass ratio of positive electrode material: conductive agent: binder meets 96:2:2.

[0108] The positive electrode material of Examples 1-12 and Comparative Examples 1-3 is selected from LiNi 0.9 Co 0.05 Mn 0.05 02; In Examples 14 and 15 and Comparative Examples 4-5, the positive electrode material is selected from lithium iron phosphate.

[0109] (2) Preparation of negative electrode sheet:

[0110] The negative electrode active material graphite, conductive agent acetylene black, thickener CMC, and binder SBR are mixed, and deionized water is added as a solvent. The mixture is stirred in a vacuum mixer until the system becomes uniform to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on both surfaces of the negative electrode current collector copper foil. After drying at room temperature, it is transferred to an oven for further drying. The negative electrode sheets are then cold pressed and cut into pieces. The ratio of negative electrode graphite: conductive agent: thickener: binder is 96:1.5:1.5:1.

[0111] (3) Preparation of electrolyte:

[0112] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0113] (4) Preparation of diaphragm:

[0114] A polyethylene film was selected as the separator.

[0115] (5) Preparation of lithium-ion batteries:

[0116] The above-mentioned positive electrode sheet, separator, and negative electrode sheet are prepared in sequence through the lamination process, so that the separator is placed between the positive and negative electrode sheets to play an isolating role. After the battery cell is prepared, the battery cell is placed in the shell, the battery cover is welded, and the battery is subjected to processes such as liquid injection, formation, and constant capacity.

[0117] It should be noted that the embodiments listed above are only some possible implementation forms that may be used in the battery preparation process, and are not an exhaustive list of all implementation forms. Those skilled in the art can understand that the preparation of batteries is not limited to the selection of positive and negative electrode materials, electrolyte formulation, and diaphragm selection listed above.

[0118] Regarding the test results, combined with Table 1 above, the following is explained:

[0119] In Examples 1-12, the value of c·b·a satisfies the following: 1.5≤c·b·a≤24. Performance Test 1 shows that during thermal runaway, the pressure relief valve can open normally, the weight loss rate is greater than or equal to 40%, and surface heat can be smoothly discharged through the pressure relief valve, preventing excessive internal heating of the battery, thus meeting performance requirements. Performance Test 2 shows that the pressure relief valve does not open abnormally when the battery is operating, thus meeting performance requirements.

[0120] In Comparative Example 1, the value of c·b·a is greater than the upper limit of the formula value. After performance test 1, during thermal runaway, the pressure relief valve cannot open normally, and the weight loss rate is less than 40%, indicating that the material inside the shell has not erupted, the temperature inside the shell is too high, and the performance requirements cannot be met.

[0121] In Comparative Example 2, the value of c·b·a is less than the lower limit of the formula value. After the second performance test, the battery is abnormally turned on when working and cannot meet the performance requirements.

[0122] In Comparative Example 3, the value of c·b·a is greater than the upper limit of the formula value. According to Performance Test 1, during thermal runaway, the pressure relief valve cannot open normally, and the weight loss rate is less than 40%, indicating that the material inside the shell has not erupted, the temperature inside the shell is too high, and the performance requirements cannot be met.

[0123] Combining the comparison between Comparative Examples 1-3 and Examples 1-12, it can be seen that when the formula values ​​do not meet the range, there is a risk of unqualified weight loss rate or abnormal explosion under normal working conditions. Furthermore, when the formula values ​​do not meet the range, the performance requirements cannot be met.

[0124] In Examples 13-15, the values ​​of c·b·a satisfy the following: 1.5≤c·b·a≤24. Performance Test 1 shows that during thermal runaway, the pressure relief valve can open normally, the weight loss rate is greater than or equal to 40%, and surface heat can be smoothly discharged through the pressure relief valve, preventing excessive internal heating of the battery, thus meeting performance requirements. Performance Test 2 shows that there is no abnormal opening when the battery is operating, thus meeting performance requirements.

[0125] In Comparative Example 3, the value of c·b·a is greater than the upper limit of the formula value. According to Performance Test 1, during thermal runaway, the pressure relief valve cannot open normally, and the weight loss rate is less than 40%, indicating that the material inside the shell has not erupted, the temperature inside the shell is too high, and the performance requirements cannot be met.

[0126] In Comparative Example 4, the value of c·b·a is less than the lower limit of the formula value. After performance test 1, when thermal runaway occurs, the pressure relief valve can be opened normally, the weight loss rate is greater than or equal to 40%, and the surface heat can be smoothly discharged through the pressure relief valve, avoiding excessive heat inside the battery and meeting the performance requirements.

[0127] Combining the comparison of Comparative Examples 3-4 and Examples 13-15, it can be seen that when the formula values ​​do not meet the range, there is a risk of unqualified weight loss rate or abnormal explosion under normal working conditions. Furthermore, when the formula values ​​do not meet the range, the performance requirements cannot be met.

[0128] In some embodiments, a groove is formed partially on the first wall 11 , the groove forms a weak portion 21 , and b satisfies: 0.02≤b≤0.08.

[0129] In this embodiment, the groove of the first wall 11 can be specifically realized by laser etching or stamping. Since the groove is integrally formed on the first wall 11 of the shell structure, compared with the case of providing an independent pressure relief valve, the integrally formed groove as a pressure relief valve is more difficult to explode. In order to ensure timely pressure relief under high temperature conditions, the residual thickness ratio b of the weak portion 21 is controlled to be smaller, so that when the battery thermal runaway occurs, the gas can quickly open the weak portion 21 of the pressure relief valve 2 so that the high-temperature gas can be discharged in time; at the same time, the residual thickness ratio b of the weak portion 21 cannot be controlled too small to avoid the abnormal opening of the weak portion 21 under normal working conditions of the battery. By precisely controlling the residual thickness ratio b of the weak portion 21, it is ensured that it responds quickly at high temperatures and remains stable under normal conditions.

[0130] A cavity suitable for accommodating the battery cell is formed inside the shell structure. As an optional implementation form, combined with Figure 7 As shown, the opening of the groove formed locally on the first wall 11 is set toward the cavity. Figure 6 As shown, the opening of the groove formed locally on the first wall 11 is set away from the cavity. Figure 8 As shown, the first wall 11 forms grooves on both sides facing toward the cavity and away from the cavity.

[0131] In some embodiments, combined Figure 15 As shown, the groove has an opening 51 and a bottom wall 52 , and the width of the opening 51 is greater than the width of the bottom wall 52 .

[0132] The width of the opening 51 is greater than that of the bottom wall 52, which can concentrate the heat more on the bottom wall 52, that is, in a smaller area, which is more conducive to the explosion of the pressure relief valve and the release of heat. It is also more conducive to the molding of the pressure relief valve.

[0133] In some embodiments, combined Figure 15 As shown, the width of the groove gradually decreases along the direction from the opening 51 to the bottom wall 52; along the width direction of the groove, the ratio of the width of the groove to the size of the first wall surface 11 ranges from 0.2 to 0.55.

[0134] The width of the groove gradually decreases along the direction from the opening 51 to the bottom wall 52, thereby forming a guiding effect, which is more conducive to the explosion of the pressure relief valve.

[0135] In some embodiments, combined Figure 15 As shown, the groove further includes a side wall 53 , which is located between the opening 51 and the bottom wall 52 , and the side wall 53 and the bottom wall 52 form an arc-shaped transition portion 54 .

[0136] By forming the arc-shaped transition portion 54 on the side wall 53 and the bottom wall 52 , stress concentration at the connection position between the side wall 53 and the bottom wall 52 can be avoided, thereby preventing the groove from being deformed and further avoiding affecting the blasting.

[0137] In some embodiments, combined Figure 2 As shown, the pressure relief valve 2 includes a valve plate portion 22, and the weak portion 21 surrounds the valve plate portion 22 to form a closed ring, and b satisfies: 0.025≤b≤0.08;

[0138] Or, combined Figure 3 As shown, the pressure relief valve 2 also includes a compacted portion 12, a weak portion 21 is arranged around the outer periphery of the valve plate portion 22 and forms a non-closed ring, and the compacted portion 12 is formed in the ring-shaped area where the weak portion 21 is not provided; b satisfies: 0.02≤b≤0.07.

[0139] When the weak portion 21 surrounds the valve plate portion 22 to form a closed ring, the valve plate portion 22 is evenly stressed, ensuring rapid opening during pressure relief. By reasonably selecting the value range of the residual thickness ratio b of the weak portion 21, the pressure relief efficiency is guaranteed, false triggering is avoided, and the overall safety performance of the battery is improved.

[0140] When formed into a non-closed ring, the compacted portion 12 serves as a connecting structure when the pressure relief valve 2 explodes, maintaining the connection between the valve plate 22 and the rest of the first wall 11, preventing fragments from flying during pressure relief and further ensuring battery safety. By properly selecting the value range of the residual thickness ratio b of the weak portion 21, efficient pressure relief is achieved while preventing the compacted portion 12 from tearing during pressure relief, thereby improving the overall safety of the battery.

[0141] In some embodiments, combined Figure 9 or Figure 10 or Figure 11 or Figure 12 As shown, the shell structure is formed with a first groove portion 23 , a second groove portion 24 is formed in the first groove portion 23 , and b satisfies: 0.015≤b≤0.08.

[0142] By forming a first groove portion 23 in the shell structure and further forming a second groove portion 24 in the first groove portion 23, the first groove portion 23 is utilized to enhance the local strength of the shell structure, reduce stress concentration, and prevent deformation of the shell structure from affecting the second groove portion 24, thereby making the second groove portion 24 more stable, ensuring that the second groove portion 24 can respond accurately at high temperatures, further optimizing the pressure relief effect, and improving the safety and reliability of the overall structure.

[0143] In this embodiment, the second groove 24 is the specific implementation location of the weak portion 21. Since the second groove 24 is more stable, the residual thickness ratio b of the weak portion 21 has a more precise value range, and the mass proportion c of Ti in the shell structure can be appropriately increased.

[0144] In some embodiments, combined Figure 10 As shown, a cavity suitable for accommodating the battery cell is formed inside the shell structure; the second groove portion 24 includes a second inner groove portion 241 with an opening facing the cavity.

[0145] In some embodiments, combined Figure 9 As shown, a cavity suitable for accommodating the battery cell is formed inside the shell structure; the second groove portion 24 includes a second outer groove portion 242 with an opening facing away from the cavity.

[0146] In some embodiments, combined Figure 11 or Figure 12As shown, a cavity suitable for accommodating the battery cell is formed inside the shell structure; the second groove portion 24 includes a second inner groove portion 241 with an opening toward the cavity and a second outer groove portion 242 with an opening away from the cavity; the second inner groove portion 241 and the second outer groove portion 242 are arranged opposite to each other; b satisfies: 0.025≤b≤0.075.

[0147] When the second groove portion 24 includes a second inner groove portion 241 opening toward the cavity and a second outer groove portion 242 opening away from the cavity, the two are arranged relative to each other. This allows the pressure relief valve 2 to more easily open in the event of thermal runaway, discharging internal heat promptly and effectively preventing excessive internal pressure and the risk of explosion. Therefore, the residual thickness ratio b of the weak portion 21 must be strictly controlled to prevent premature rupture under high temperature and pressure, ensuring that the pressure relief valve 2 can be reliably activated at critical moments.

[0148] In some embodiments, the area of ​​the enclosed region of the pressure relief valve 2 is S1, and the area of ​​the first wall 11 is S2, satisfying: 0.03≤S1 / S2≤0.06.

[0149] By increasing the ratio of S1 / S2, the opening area of ​​pressure relief valve 2 can be effectively adjusted, increasing the opening space during thermal runaway. This allows heat and gas inside the housing to be more fully discharged during thermal runaway, thereby improving pressure relief efficiency. However, increasing the opening area of ​​pressure relief valve 2 makes it more difficult to open. Further control is needed to control the range of the values ​​in the formula c·b·a to ensure that pressure relief valve 2 can still open smoothly under high temperature and high pressure environments, balancing pressure relief efficiency and opening difficulty, and further improving the safety and reliability of the housing structure.

[0150] Illustratively, in this embodiment, the value of S1 / S2 may be 0.03, 0.04, 0.05, 0.06, etc., or may be an interval formed by any two of the above values.

[0151] The housing structure of this embodiment also includes a terminal 3, which serves as the current output terminal of the battery. The terminal 3 can be made of aluminum, a copper-aluminum composite material, or other materials. The housing structure 1 includes a housing body 10, with the terminal 3 disposed on one of the walls of the housing body 10. As a variation, the housing structure 1 includes the housing body 10 and a cover plate 14. The housing body 10 has an opening formed therein. The cover plate 14 covers the opening of the housing body 10 and is secured by a sealing structure to ensure the stability and safety of the internal environment of the battery. The terminal 3 can also be disposed on the cover plate 14, insulated from the housing body 10.

[0152] In some embodiments, combined Figure 1 As shown, the shell structure further includes a pole 3 , and the pressure relief valve 2 and the pole 3 are both arranged on the first wall 11 , and b satisfies: 0.018≤b≤0.075.

[0153] Because the terminal 3 acts as a flow control point and generates considerable heat during operation, placing both the pressure relief valve 2 and the terminal 3 on the first wall 11 can easily lead to localized overheating of the first wall 11, affecting the proper functioning of the pressure relief valve 2 and increasing the risk of abnormal explosion. Therefore, it is necessary to strictly control the residual thickness ratio b of the weak portion 21 to ensure that the first wall 11 maintains structural stability even in high-temperature environments, preventing malfunction of the pressure relief valve 2 caused by localized overheating and effectively reducing safety risks.

[0154] In some other embodiments, the shell structure further includes a pole 3 , which is disposed on the second wall 15 . The second wall 15 and the first wall 11 are disposed on opposite sides of the shell structure, and b satisfies: 0.025≤b≤0.08.

[0155] The pressure relief valve 2 is mounted on the first wall 11, and the terminal 3 is mounted on the second wall 15. The second wall 15 and the first wall 11 are positioned on opposite sides of the housing structure, achieving thermal and electrical separation and improving battery safety. By controlling the residual thickness ratio b of the weak portion 21, the pressure relief valve 2 can be opened promptly under high temperature and pressure while preventing the terminal 3 from being accidentally ejected due to excessive opening pressure.

[0156] In some embodiments, when c satisfies: c ≥ 99.5%, b satisfies: 0.01 ≤ b ≤ 0.075;

[0157] In some embodiments, when c satisfies: 60%≤c<99.5%, b satisfies: 0.02≤b≤0.09.

[0158] When the c content is high, the overall strength of the housing structure 1 is also increased, making it more difficult for the pressure relief valve 2 to open, making it more difficult to dissipate heat during thermal runaway. When c satisfies the following conditions: c ≥ 99.5%, by further controlling b within the range of 0.01 ≤ b ≤ 0.075, the gas can quickly open the weak portion 21 of the pressure relief valve 2 in the event of thermal runaway, allowing the high-heat gas to be discharged in a timely manner. When c satisfies the following conditions: 60% ≤ c ≤ 99.5%, by further controlling b within the range of 0.01 ≤ b ≤ 0.075, it ensures a rapid response at high temperatures and stability under normal conditions.

[0159] In some embodiments, the shell structure includes Al, and b satisfies: 0.2≤b≤0.8. The addition of Al facilitates the opening of the pressure relief valve, and the residual thickness of the weak portion 21 can be increased to prevent abnormal opening of the pressure relief valve under normal circumstances.

[0160] In some embodiments, the shell structure is cylindrical and satisfies: 5≤c·b·a≤24.

[0161] Because the cylindrical housing structure is symmetrically stressed under thermal expansion and mechanical stress, deformation is minimal during long-term cycling, thereby improving the stability and reliability of the pressure relief valve 2 and reducing the risk of pressure relief failure due to housing deformation. Furthermore, the cylindrical housing structure allows the battery to better disperse stress when subjected to external impact, enhancing the overall structure's impact resistance and effectively preventing housing rupture. By rationally selecting the c·b·a value range, the housing structure maintains excellent performance in both high-temperature and impact environments, ensuring a timely response from the pressure relief valve while preventing false triggering.

[0162] In some embodiments, the shell structure is a quadrangular prism, satisfying: 1.5≤c·b·a≤20.

[0163] A quadrangular prism offers advantages in terms of space utilization. However, due to the uneven stress distribution along its edges, this can lead to localized stress concentrations, increasing the risk of deformation. Thermal expansion and mechanical stress can easily lead to localized stress concentrations, making edges or corners more susceptible to damage. Precise control of the c·b·a values ​​is necessary to balance the stress distribution along the edges and prevent localized deformation. This ensures the stability of the housing structure under high temperatures and impacts, enabling timely pressure relief and preventing false triggering, thereby enhancing overall battery safety.

[0164] In some embodiments, the thickness b2 of the first wall 11 satisfies: 0.2 mm ≤ b2 ≤ 2.0 mm.

[0165] By limiting the thickness b2 of the first wall 11 to a value within the range of 0.2 mm ≤ b2 ≤ 2.0 mm, it is ensured that it has sufficient strength to resist external impact and internal pressure; the wall is prevented from being too thick, which leads to an increase in weight, and its good thermal conductivity is guaranteed, thereby ensuring strength while meeting lightweight requirements, avoiding weight increase and reduced heat dissipation efficiency caused by the excessive thickness b2 of the first wall 11, and reducing the difficulty of processing the residual thickness of the weak portion 21.

[0166] Illustratively, in this embodiment, the value of b2 can be 0.2 mm or 0.3 mm or 0.4 mm or 0.5 mm or 0.8 mm or 1 mm or 1.3 mm or 1.5 mm or 1.8 mm or 1.92 mm or 2 mm, etc., or it can be an interval range formed by any two of the above values.

[0167] In some embodiments, the residual thickness b1 of the weak portion 21 satisfies the following range: 0.02 mm ≤ b1 ≤ 0.25 mm.

[0168] By precisely controlling the value of b1, the weak portion 21 is ensured to have sufficient structural strength under extreme conditions to prevent the shell from rupturing. At the same time, the opening sensitivity of the pressure relief valve 2 is optimized, further improving the overall safety and reliability of the battery system.

[0169] Illustratively, in this embodiment, the value of b1 may be 0.02 mm or 0.03 mm or 0.05 mm or 0.08 mm or 0.1 mm or 0.12 mm or 0.15 mm or 0.18 mm or 0.mm or 0.23 mm or 0.25 mm, etc., or may be an interval formed by any two of the above values.

[0170] In some embodiments, the shell structure includes a shell body 10 and a cover plate 14 , the wall thickness of the shell body 10 is smaller than that of the cover plate 14 , and the pressure relief valve 2 is disposed on the shell body 10 , satisfying: 0.01≤b≤0.08.

[0171] Since the wall thickness of the shell body 10 is smaller than that of the cover plate 14, the pressure relief valve 2 is arranged on the shell body 10, which makes the opening sensitivity of the pressure relief valve 2 on the shell body 10 higher and can be started under a relatively low pressure. It is necessary to control the value range of the formula c·b·a, not only to ensure that the pressure relief valve 2 can be opened smoothly under high temperature and high pressure environment, but also to avoid the pressure relief valve 2 from opening prematurely due to the thin wall thickness.

[0172] In some other embodiments, the shell structure includes a shell body 10 and a cover plate 14 , the wall thickness of the shell body 10 is smaller than the wall thickness of the cover plate 14 , and the pressure relief valve 2 is arranged on the cover plate 14 , satisfying: 0.02≤b≤0.09.

[0173] Since the wall thickness of the shell body 10 is smaller than that of the cover plate 14 , the pressure relief valve 2 is arranged on the cover plate 14 , and the opening stability of the pressure relief valve 2 on the cover plate 14 is higher. It is necessary to precisely control the value range of the formula c·b·a to ensure that the pressure relief valve 2 can be opened reliably in the event of thermal runaway, while avoiding the opening delay caused by the difference in wall thickness, thereby further improving the overall safety performance.

[0174] In some embodiments, 4≤c·b·a≤18 is satisfied.

[0175] The shell structure 1 provided in the embodiment of the present invention achieves lightweighting of the shell structure 1 by comprehensively controlling the relationship between a, b, and c, thereby avoiding abnormal explosion of the battery during normal charging and discharging, and improving the energy density of the battery. At the same time, it can ensure that when the battery thermally runs away, the pressure relief valve 2 can be opened in time to effectively discharge internal heat and avoid explosion of the shell, thereby taking into account both lightweighting and safety.

[0176] According to another aspect of an embodiment of the present invention, a battery is provided, comprising:

[0177] and the shell structure as described above, wherein a cavity is formed inside the shell structure, and the cavity is suitable for accommodating the battery core 4.

[0178] In this embodiment, the battery can be a cylindrical battery made in a wound form. The battery cell 4 includes a battery cell body 41 and tabs, wherein the tabs can include a positive tab 42 and a negative tab 43.

[0179] The tabs are key components of the battery, used to transmit and extract the current within the cell. The tabs can be made of the same material as the current collector. For example, the tabs can be made of silver-plated aluminum, silver-plated stainless steel, stainless steel, copper, aluminum, nickel, carbon, nickel, or titanium. Furthermore, the tabs can be cut from the current collector or formed as separate metal parts. It is understood that the positive tab 42 is electrically connected to the positive electrode sheet in the cell body 41, and the negative tab 43 is electrically connected to the negative electrode sheet in the cell body 41.

[0180] In some embodiments, the battery cell 4 includes a battery cell body 41 and a positive electrode tab 42 and a negative electrode tab 43;

[0181] The positive electrode tab 42 and the negative electrode tab 43 are located on the same side of the battery cell body 41 and are arranged on the same side as the pressure relief valve 2; b satisfies: 0.02≤b≤0.08.

[0182] The positive electrode tab 42 and the negative electrode tab 43 are located on the same side of the battery cell body 41. The positive electrode tab 42 and the negative electrode tab 43 can be electrically connected to the pole respectively; or one of them can be electrically connected to the pole and the other can be electrically connected to the battery shell structure 1.

[0183] When the positive electrode tab 42 and the negative electrode tab 43 are located on the same side of the battery cell body 41, the current path can be effectively shortened, reducing internal resistance. Furthermore, when the positive electrode tab 42, the negative electrode tab 43, and the pressure relief valve 2 are located on the same side, the tabs act as overcurrent relief devices, generating significant heat during operation. This can easily lead to localized overheating of the first wall 11, affecting the proper functioning of the pressure relief valve 2 and increasing the risk of abnormal explosion. Therefore, the residual thickness ratio b of the weak portion 21 must be strictly controlled to ensure that the first wall 11 maintains structural stability even in high-temperature environments, preventing malfunction of the pressure relief valve 2 due to localized overheating, and thus effectively reducing safety risks.

[0184] In some embodiments, the battery cell 4 includes a battery cell body 41 and a positive electrode tab 42 and a negative electrode tab 43;

[0185] The positive electrode tab 42 and the negative electrode tab 43 are located on the same side of the battery cell body 41 and are arranged on the opposite side of the pressure relief valve 2; b satisfies: 0.01≤b≤0.07.

[0186] When the positive electrode tab 42 and the negative electrode tab 43 are located on the same side of the battery cell body 41, the current path can be effectively shortened and the internal resistance can be reduced. Furthermore, when the tab and the pressure relief valve 2 are located on opposite sides, thermal and electrical separation is achieved, improving the safety performance of the battery. However, due to the limited internal space of the shell structure, if the pressure relief valve 2 cannot promptly release the heat from the shell structure, the heat from the shell structure will also impact the side where the pole is located, causing the connection between the pole 3 and the shell to fail, the pole 3 to be ejected, and thus the problem of electrical connection failure. In this case, by controlling the residual thickness ratio b of the weak portion 21, the timely opening of the pressure relief valve 2 under high temperature and high pressure can be ensured, while the accidental ejection of the pole 3 due to excessive opening pressure can be avoided.

[0187] In some embodiments, the battery cell 4 includes a battery cell body 41 and a positive electrode tab 42 and a negative electrode tab 43;

[0188] The positive electrode tab 42 and the negative electrode tab 43 are located on opposite sides of the battery cell body 41; b satisfies: 0.02≤b≤0.075.

[0189] The positive electrode tab 42 and the negative electrode tab 43 are located on opposite sides of the battery cell body 41. The positive electrode tab 42 and the negative electrode tab 43 can be electrically connected to the pole respectively; or one of them can be electrically connected to the pole and the other can be electrically connected to the battery shell structure 1.

[0190] The positive and negative tabs 42 and 43 are located on opposite sides of the cell body 41. This results in a longer current path through one tab, increasing the current path and internal resistance, which can lead to excessive heat generation within the battery. By controlling the residual thickness ratio b of the weak portion 21, the pressure relief valve 2 can be opened smoothly while reducing the risk of abnormal opening, ensuring the stability and safety of the battery in high-temperature and high-pressure environments.

[0191] In some embodiments, the battery cell 4 includes a positive electrode sheet and a negative electrode sheet, wherein the thickness of the positive electrode sheet is f, which satisfies: 80 μm≤f≤150 μm.

[0192] When the thickness f of the positive electrode sheet increases, the internal resistance of the battery cell also increases, resulting in an increase in heat generation. It is necessary to further control the value range of the formula c·b·a to ensure that the pressure relief valve 2 can respond in a timely manner under high temperature and high pressure environments, reasonably control the opening difficulty, and further improve the safety and reliability of the shell structure.

[0193] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the present invention.

Claims

1. A housing structure, characterized in that: The shell structure includes Ti element; A pressure relief valve (2) is provided on the first wall surface (11) of the shell structure, and the bursting pressure of the pressure relief valve (2) is a; The pressure relief valve (2) includes a weak portion (21), the residual thickness of the weak portion (21) is b1, the thickness of the first wall (11) is b2, and the residual thickness ratio of the weak portion (21) is b, wherein b=b1 / b2; The mass of the Ti element of the shell structure accounts for c of the total mass of all elements of the shell structure; wherein c ≥ 60%; And it satisfies: 1.5≤c·b·a≤24.

2. The housing structure according to claim 1, wherein: The a satisfies: 1.3Mpa≤a≤2.6Mpa; And / or, b satisfies: 0.01≤b≤0.1; And / or, c satisfies: 60%≤c≤99.99%.

3. The housing structure according to claim 1, wherein: A groove is partially formed on the first wall surface (11), the groove forms the weak portion (21), and b satisfies: 0.02≤b≤0.

08.

4. The housing structure according to claim 3, characterized in that: The groove has an opening portion (51) and a bottom wall (52), and the width of the opening portion (51) is greater than the width of the bottom wall (52).

5. The housing structure according to claim 4, characterized in that: The width of the groove gradually decreases in a direction from the opening (51) toward the bottom wall (52).

6. The housing structure according to claim 3, characterized in that: Along the width direction of the groove, the ratio of the width direction of the groove to the size of the first wall surface (11) ranges from 0.2 to 0.

55.

7. The housing structure according to claim 4, characterized in that: The groove further comprises a side wall (53), wherein the side wall (53) is located between the opening portion (51) and the bottom wall (52), and the side wall (53) and the bottom wall (52) form an arc-shaped transition portion (54).

8. The housing structure according to claim 1, wherein: The pressure relief valve (2) comprises a valve plate portion (22), the weak portion (21) surrounds the valve plate portion (22) to form a closed ring, and b satisfies: 0.025≤b≤0.08; Alternatively, the pressure relief valve (2) further includes a compacted portion (12), the weak portion (21) is arranged around the outer periphery of the valve plate portion (22) and forms a non-closed ring, the compacted portion (12) is formed in an area of ​​the ring where the weak portion (21) is not provided; and b satisfies: 0.02≤b≤0.

07.

9. The housing structure according to claim 3, wherein: The housing structure is formed with a first groove portion (23), a second groove portion (24) is formed in the first groove portion (23), and b satisfies: 0.015≤b≤0.08; A cavity suitable for accommodating a battery cell is formed inside the shell structure; the second groove portion (24) includes a second inner groove portion (241) opening toward the cavity and / or the second groove portion (24) includes a second outer groove portion (242) opening away from the cavity.

10. The housing structure according to claim 9, characterized in that: A cavity suitable for accommodating a battery cell is formed inside the shell structure; the second groove portion (24) includes a second inner groove portion (241) with an opening toward the cavity and a second outer groove portion (242) with an opening away from the cavity; The second inner groove portion (241) and the second outer groove portion (242) are arranged opposite to each other; and b satisfies the following conditions: 0.025≤b≤0.

075.

11. The housing structure according to claim 1, wherein: The area of ​​the enclosed region of the pressure relief valve (2) is S1, and the area of ​​the first wall surface (11) is S2, satisfying: 0.03≤S1 / S2≤0.

06.

12. The housing structure according to claim 1, wherein: The shell structure further includes a pole (3), the pressure relief valve (2) and the pole (3) are both arranged on the first wall surface (11), and b satisfies: 0.018≤b≤0.

075.

13. The housing structure according to claim 1, wherein: The shell structure further includes a pole (3), the pole (3) being arranged on a second wall surface (15), the second wall surface (15) and the first wall surface (11) being arranged on two sides of the shell structure opposite to each other, and b satisfies: 0.025≤b≤0.

08.

14. The housing structure according to claim 1, wherein: When the c satisfies: c≥99.5%, the b satisfies: 0.01≤b≤0.

075.

15. The housing structure according to claim 1, wherein: When the c satisfies: 60%≤c<99.5%, the b satisfies: 0.02≤b≤0.

09.

16. The housing structure according to claim 1, wherein: The shell structure includes Al element, and b satisfies: 0.2≤b≤0.

8.

17. The housing structure according to claim 1, wherein: The shell structure is cylindrical and satisfies: 5≤c·b·a≤24.

18. The housing structure according to claim 1, wherein: The shell structure is a quadrangular prism, satisfying: 1.5≤c·b·a≤20.

19. The housing structure according to claim 1, wherein: The thickness b2 of the first wall surface (11) satisfies: 0.2 mm ≤ b2 ≤ 2.0 mm.

20. The housing structure according to claim 1, wherein: The residual thickness b1 of the weak portion (21) satisfies the following value range: 0.02 mm ≤ b1 ≤ 0.25 mm.

21. The housing structure according to claim 1, wherein: The shell structure comprises a shell body (10) and a cover plate (14); the wall thickness of the shell body (10) is smaller than the wall thickness of the cover plate (14); the pressure relief valve (2) is arranged on the shell body (10), and satisfies the following conditions: 0.01≤b≤0.

08.

22. The housing structure according to claim 1, wherein: The shell structure comprises a shell body (10) and a cover plate (14); the wall thickness of the shell body (10) is smaller than the wall thickness of the cover plate (14); the pressure relief valve (2) is arranged on the cover plate (14), and satisfies the following conditions: 0.02≤b≤0.

09.

23. The housing structure according to claim 1, wherein: Satisfies: 4≤c·b·a≤18.

24. A battery, characterized in that: include: Battery cells (4); as well as The housing structure according to any one of claims 1 to 23, wherein a cavity is formed inside the housing structure, and the cavity is suitable for accommodating the battery core (4).

25. The battery according to claim 24, characterized in that The battery cell (4) comprises a battery cell body (41), a positive electrode tab (42), and a negative electrode tab (43); The positive electrode tab (42) and the negative electrode tab (43) are located on the same side of the battery cell body (41) and are arranged on the same side as the pressure relief valve (2); and b satisfies: 0.02≤b≤0.

08.

26. The battery according to claim 24, characterized in that The battery cell (4) comprises a battery cell body (41), a positive electrode tab (42), and a negative electrode tab (43); The positive electrode tab (42) and the negative electrode tab (43) are located on the same side of the battery cell body (41) and are arranged on the opposite side of the pressure relief valve (2); and b satisfies: 0.01≤b≤0.

07.

27. A battery pack, characterized in that: include: A box and a plurality of batteries according to any one of claims 24 to 26, wherein the box comprises a bottom plate and a plurality of side plates, and the batteries are fixed to the bottom plate of the box.

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