A battery and its manufacturing method, a battery pack, a battery module, and an electrical device thereof.

Abstract

The present invention provides a battery, a method for manufacturing the same, a battery pack, a battery module, and an electrical device. The initial internal pressure of the battery is T MPa, where T satisfies 0 < T < 0.25. By defining the initial internal pressure of the battery as T MPa, the present invention effectively suppresses the gas generation side reaction of the battery, thereby avoiding potential safety hazards such as battery swelling, leakage, and thermal runaway caused by the gas generation side reaction, and improving the safety of battery use.

Description

Technical Field

[0001] This invention relates to the field of battery devices, and more particularly to a battery and its preparation method, a battery pack, a battery module, and an electrical device. Background Technology

[0002] Lithium-ion batteries have many advantages, such as high energy density, low self-discharge, wide operating temperature range, excellent cycle performance, good rate performance, and high output power. Therefore, lithium-ion batteries play a crucial role in the current wave of automotive electrification and intelligent energy storage.

[0003] However, due to the inherent flammability of the materials used in lithium-ion batteries, they are highly susceptible to thermal runaway under abusive conditions. Therefore, the safety of lithium-ion batteries has always been a major concern. Gas production is a common phenomenon during the charging and discharging process of lithium-ion batteries. Gas production increases the occurrence of internal side reactions and leads to poor contact between the positive and negative electrodes and the separator, resulting in increased positive electrode resistance, increased battery swelling, and localized lithium deposition. This causes a decrease in battery cycle life and rate performance, and also increases the risk of internal short circuits, leading to a rapid increase in local temperature and potentially thermal runaway. Therefore, to improve battery safety, it is necessary to suppress gas production reactions in lithium-ion batteries. Summary of the Invention

[0004] The present invention provides a battery that produces less gas during cycling, thus exhibiting higher safety in use.

[0005] The present invention also provides a method for preparing a battery, which can prepare the above-mentioned battery and is simple to operate and has low cost.

[0006] The present invention also provides a battery pack, which, because it includes the aforementioned battery, produces less gas during use, thereby reducing the risks of expansion, leakage, thermal runaway, etc. caused by gas production problems.

[0007] The present invention also provides a battery pack, which, since it includes the above-mentioned battery pack, can reduce safety issues caused by gas generation during use.

[0008] The present invention also provides an electrical device, which, since it includes at least one of the above-mentioned battery, battery pack, and battery module, has the advantages of long service life and high safety index.

[0009] In detail, in a first aspect, the present invention provides a battery having an initial internal pressure of T MPa, wherein T satisfies: 0 <T<0.25。

[0010] Furthermore, the battery contains a first gas and / or a second gas, wherein the first gas includes at least one of nitrogen, argon, and helium; and the second gas includes at least one of oxygen, carbon dioxide, carbon monoxide, methane, ethylene, and hydrogen.

[0011] Furthermore, the gas includes a first gas and a second gas, wherein the volume ratio of the first gas and the second gas is 0-60.

[0012] Furthermore, the battery also includes an electrolyte comprising a carbonate-based organic solvent, and the interior of the battery contains carbon dioxide.

[0013] Furthermore, the battery is prepared by a method comprising the following processes:

[0014] After the battery pre-product undergoes formation and capacity testing, the casing is fixed along the direction of the electrode assembly, gas is injected to make the internal pressure of the battery pre-product T MPa, and then it is welded and packaged to obtain the finished battery product.

[0015] In a second aspect, the present invention provides a method for preparing a battery as described in the first aspect, comprising the following steps:

[0016] The electrode assembly is placed in a housing containing an injection port. Electrolyte is injected through the injection port, and the injection port is sealed to obtain a pre-finished battery.

[0017] After the battery pre-product undergoes formation and capacity testing, the housing is fixed along the direction of the electrode assembly, the liquid injection port is opened, and gas is injected to make the internal pressure of the battery pre-product T MPa. The liquid injection port is then welded and sealed to obtain the finished battery product.

[0018] Further, fixing the housing along the direction of the electrode assembly includes the following steps:

[0019] The housing is fixed along the direction of the electrode assembly using a tooling fixture; or, the pre-assembled battery components are assembled into a battery pack or battery group to fix the housing.

[0020] Thirdly, the present invention provides a battery pack comprising the battery described in the first aspect.

[0021] Fourthly, the present invention provides a battery pack comprising the battery pack described in the third aspect.

[0022] Fifthly, the present invention provides an electrical device comprising at least one of the battery described in the first aspect, the battery pack described in the third aspect, and the battery module described in the fourth aspect.

[0023] The battery provided by this invention effectively suppresses the gas-generating side reaction by limiting its initial internal pressure to T MPa, thereby avoiding safety hazards such as battery expansion, leakage and thermal runaway caused by the gas-generating side reaction, and improving the safety of battery use. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of the application will be clearly and completely described below in conjunction with the embodiments of the invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] In this invention, the term "and / or" describes the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0026] In this invention, the term "at least one" refers to one or more items, and "more than one" refers to two or more items. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0027] In a first aspect, the present invention provides a battery, wherein the initial internal pressure of the battery is T MPa, wherein T satisfies: 0 <T<0.25。

[0028] The initial internal pressure of the battery mentioned above refers to the internal pressure of the battery after formation, capacity testing, and removal from the production line, before it has been used again. Normally, the initial internal pressure of a battery is negative. The above embodiment limits the initial internal pressure of the battery to TMPa, which can slow down the initial gas-generating side reactions of the battery, thereby suppressing the gas generation rate of these side reactions. However, the initial internal pressure of the battery should not be too high. If T is greater than or equal to 0.25MPa, the initial internal pressure of the battery is too high, and the battery expands severely with the increase of cycle number, leading to premature battery failure.

[0029] In one optional embodiment, the battery contains a first gas and / or a second gas, wherein the first gas includes at least one of nitrogen, argon, and helium; and the second gas includes at least one of oxygen, carbon dioxide, carbon monoxide, methane, ethylene, and hydrogen.

[0030] It can be understood that the gas inside the battery is the main reason why the initial internal pressure of the battery is positive. By limiting the first gas and the second gas in the above-described embodiment, on the one hand, it helps to increase the internal pressure of the battery, thereby suppressing the gas production rate of the gas-producing reaction. On the other hand, when the battery contains the second gas, in addition to increasing the internal pressure of the battery, it can also specifically suppress the gas-producing side reactions that are consistent with the second gas during the battery chemical reaction process.

[0031] In one optional embodiment, the gas comprises a first gas and a second gas, with a volume ratio of 0-60 between the first and second gases. When the gas contains only the first gas (an inert protective gas), it can compress the reaction space; higher pressure compresses the internal space of the battery, reducing the space for gas molecules to move. This may inhibit some gas-generating reactions, as reactions require space for molecular rearrangement and recombination. When the gas also contains the second gas, according to the principle of chemical equilibrium, pressure changes can affect the equilibrium of the chemical reaction. For some reversible gas-generating reactions, increasing the pressure may shift the reaction towards a direction with reduced gas volume, thereby reducing gas production.

[0032] For example, the volume ratio of the first gas to the second gas is any value or a range of any two of the following: 1, 5, 6, 7, 10, 20, 30, 40, 50, 60.

[0033] In an alternative embodiment, the battery further includes an electrolyte, which generally comprises an organic solvent, wherein the organic solvent serves as a medium for transporting ions in the electrochemical reaction, and may be an organic solvent known in the art for use in battery electrolytes.

[0034] In one alternative embodiment, the electrolyte comprises a carbonate organic solvent, and the interior of the battery comprises carbon dioxide.

[0035] CO2 is the main component of gas produced by lithium-ion batteries, and the oxidative decomposition of carbonate organic solvents is the main source of CO2. Therefore, when the electrolyte includes carbonate organic solvents, the corresponding CO2 can be added to the battery to break the chemical equilibrium of the oxidative decomposition reaction of carbonate organic solvents, thereby inhibiting the oxidative decomposition of carbonate organic solvents and reducing the CO2 gas generation rate.

[0036] In some embodiments, the battery contains 60%-80% of a first gas and 20%-30% of CO2 gas by weight.

[0037] For example, carbonate organic solvents may be ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), and butylene carbonate (BC).

[0038] In addition to carbonate organic solvents, the electrolyte may also include other organic solvents, such as at least one of the following: 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), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0039] The electrolyte also includes an electrolyte salt, which serves as an ion source and can be any electrolyte salt known in the art for use in battery electrolytes. This includes, but is not limited to, at least one of: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonyate (LiSbF6), lithium difluorophosphate (LiPF2O2), lithium 4,5-dicyano-2-trifluoromethylimidazolium (LiDTI), lithium dioxoborate (LiBOB), lithium trifluoromethanesulfonate (LiTFS), lithium nitrate (LiNO3), and lithium fluoride (LiF).

[0040] The electrolyte may also include additives, such as vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3-propane sulfonate lactone, fluoroethylene carbonate (FEC), trifluoromethyl vinyl carbonate, dimethyl sulfate, vinyl sulfate, methyl vinyl sulfate, propylene sulfate, vinyl sulfite, succinic anhydride, biphenyl, toluene, xylene, cyclohexylbenzene, fluorobenzene, p-fluorotoluene, tert-butylbenzene, tert-amylbenzene, propylene sulfonate lactone, butane sulfonate lactone, methane disulfonate methylene, hexamethyldisilazane, heptamethyldisilazane, and heptamethyldisilazane. The following is a list of at least one of the following: dimethyl methylphosphonate, diethyl ethylphosphonate, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, triphenyl phosphite, tris(trimethylsilyl)phosphate, acetonitrile (AN), malononitrile, succinic anion (SN), glutaronitrile (GN), adiponitrile (ADN), 1,3,6-hexanetrionitrile, ethylene glycol dipropionitrile ether, pentafluoroethoxycyclotriphosphonon, 1,4-dicyano-2-butene, p-methylbenzonitrile, 2-fluoroadiponitrile, 2,2-difluorosuccinic anion, tricyanobenzene, acrylonitrile, crotonitrile, trans-butenedionitrile, and trans-hexenedionitrile.

[0041] It is understood that the battery of the present invention may also include a positive electrode, a negative electrode, and a separator.

[0042] The aforementioned positive electrode sheet includes a current collector and a positive electrode paste disposed on at least one functional surface of the current collector. The positive electrode paste includes a positive electrode active material, a conductive agent, and a binder. This invention does not particularly limit the positive electrode active material. Exemplarily, the positive electrode active material can be one or more commonly used in the art, such as lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium iron phosphate; lithium manganese oxide can be LiMnO2 or LiMn2O4; and lithium nickel cobalt manganese oxide can be LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1One or more of O2; the material of the current collector can be selected from one or more of foam metal mesh, copper foil, titanium foil, tin foil, chromium foil, and composite foils of the above metals; to improve the energy density of the battery, preferably, the paste is sequentially applied to the two functional surfaces of the current collector; the conductive agent can be selected from at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, metal powder, and graphene; the binder can be selected from at least one of carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate; the areal density and compaction of the positive electrode sheet are not specifically limited in this invention, and those skilled in the art can make corresponding designs according to the corresponding electrochemical system. For example, the areal density of the positive electrode sheet on both sides is 300-500 g / m³. 2 The compacted density is 2.3–3.0 g / cm³. 3 .

[0043] The aforementioned negative electrode sheet includes a current collector and a negative electrode paste disposed on at least one functional surface of the current collector. The negative electrode paste includes a negative electrode active material, a conductive agent, and a binder. The negative electrode active material includes one or more of graphite, hard carbon, soft carbon, silicon-based negative electrode, titanium-based material, nitride, tin compound, and lithium metal. The negative electrode current collector can be a conventional negative electrode current collector in the art, such as copper foil. The aforementioned conductive agent can be selected from at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotube, metal powder, and graphene. The binder can be selected from at least one of carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate.

[0044] The aforementioned diaphragm can be any known porous membrane with electrochemical and chemical stability, such as at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The diaphragm can be single-layered or multi-layered.

[0045] In an alternative embodiment, the battery is prepared by a method comprising the following processes:

[0046] After the battery pre-product undergoes formation and capacity testing, the housing is fixed along the direction of the electrode assembly, the liquid injection port is opened, and gas is injected to make the internal pressure of the battery pre-product T MPa. The liquid injection port is then welded and sealed to obtain the finished battery product.

[0047] The above method involves injecting gas before the battery is put into use, creating a positive pressure inside the battery. This disrupts the chemical equilibrium of the initial gas-producing side reactions, thereby reducing the gas production rate of the side reactions.

[0048] In a second aspect, the present invention provides a method for preparing a battery as described in the first aspect, comprising the following steps:

[0049] The electrode assembly is placed in a housing containing an injection port. Electrolyte is injected through the injection port, and the injection port is sealed to obtain a pre-finished battery.

[0050] After the battery pre-product undergoes formation and capacity testing, the housing is fixed along the direction of the electrode assembly, the liquid injection port is opened, and gas is injected to make the internal pressure of the battery pre-product T MPa. The liquid injection port is then welded and sealed to obtain the finished battery product.

[0051] The preparation of the above-mentioned battery pre-finished products and the processes such as formation and capacity testing are consistent with those of conventional batteries. In some embodiments, the electrode assembly includes: a positive electrode sheet, a separator, and a negative electrode sheet. The preparation method includes: stacking the positive electrode sheet, the separator, and the negative electrode sheet in sequence to obtain the electrode assembly, or stacking the positive electrode sheet, the separator, and the negative electrode sheet in sequence and then winding them to obtain the electrode assembly.

[0052] In some embodiments, the housing is an aluminum-plastic film housing; the injection coefficient of the injected electrolyte is generally 2.0 to 4.5 g / Ah.

[0053] In some embodiments, the formation and capacity testing process includes: S1, placing the pre-finished battery in a formation cabinet, ensuring good battery connection, and performing initial charging in constant current-constant voltage (CC-CV) mode. In the constant current stage, the battery is charged with a set current until the voltage reaches a set value. In the constant voltage stage, the voltage is kept constant while the current gradually decreases until the current drops to a set cutoff value; S2, performing initial discharge in constant current (CC) mode, setting the discharge parameters of the formation cabinet, including current and cutoff voltage, and discharging the battery with a set current until the voltage drops to a set cutoff value; S3, repeating the above charging and discharging process to further activate battery performance.

[0054] In some embodiments, a negative pressure extraction process is included before the gas is introduced.

[0055] In some embodiments, fixing the housing along the direction of the electrode assembly includes the following steps:

[0056] The housing is fixed along the direction of the electrode assembly using a tooling fixture; or, the pre-assembled battery components are assembled into a battery pack or battery group to fix the housing.

[0057] By fixing the housing along the direction of the electrode assembly, the probability of the pre-built battery expanding due to inflation can be reduced.

[0058] Thirdly, the present invention provides a battery pack comprising the battery described in the first aspect.

[0059] In some embodiments, in order to reduce the expansion rate of the battery pre-product due to inflation, after the battery pre-product has undergone formation and capacity testing, before opening the injection port, the battery pre-product is assembled into components and then the injection port is opened for inflation.

[0060] Fourthly, the present invention provides a battery pack comprising the battery pack described in the third aspect.

[0061] Fifthly, the present invention provides an electrical device comprising at least one of the battery described in the first aspect, the battery pack described in the third aspect, and the battery module described in the fourth aspect.

[0062] It should be noted that the aforementioned electronic devices can be any conventional device that requires electricity, such as, but not limited to, computers, electric vehicles, air conditioners, refrigerators, washing machines, microwave ovens, printers, fax machines, etc.

[0063] The present invention will be further described below with reference to specific embodiments:

[0064] The following test methods involve measuring the internal pressure of the battery by piercing the seal with an internal pressure instrument and reading the internal pressure value of the battery.

[0065] Example 1

[0066] The present invention provides a battery with an initial internal pressure of 0.03 MPa.

[0067] Its preparation method includes the following steps:

[0068] S1. Preparation of positive electrode sheet: The positive electrode active material (lithium nickel cobalt manganese oxide, wherein, on a molar basis, nickel:cobalt:manganese = 7:1:2), conductive agent CNT, conductive agent SP, and binder PVDF are dissolved in NMP to form a positive electrode slurry. The positive electrode slurry is coated on both surfaces of an aluminum foil with a thickness of 13μm. After drying, rolling, and slitting, a positive electrode sheet including a positive electrode active layer is obtained. The mass ratio of positive electrode active material, CNT, SP, PVDF, and NMP in the positive electrode slurry is 100:18:0.5:1.6:25.

[0069] S2. Preparation of negative electrode sheet: Graphite, conductive agent, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber, water and NMP are mixed and stirred in a ratio of 100:1:1.5:3:130:3 to obtain a uniform negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of an 8mm thick conductive copper foil, dried at 110℃, and then slit and die-cut to obtain a negative electrode sheet including the negative electrode active layer.

[0070] S3. Preparation of electrolyte: It consists of solvent, lithium hexafluorophosphate and vinylene carbonate. The solvent is a mixture of vinylene carbonate and methyl ethyl carbonate in a mass ratio of 3:7. The concentration of lithium hexafluorophosphate is 1 mol / L and vinylene carbonate accounts for 3 wt% of the electrolyte.

[0071] S4. Assemble pre-finished battery: Stack the positive electrode sheet, polypropylene separator and negative electrode sheet in a Z-shaped stacking manner to assemble a lithium-ion battery electrode assembly in one direction. Then, hot press them to assemble them into a soft pack battery. Vacuum liquid injection is performed according to the liquid injection coefficient of 3.2g / Ah. After sealing, it undergoes high-temperature aging, formation, aging, capacity testing and vacuum final sealing to produce a square aluminum-cased battery with a length of 200mm, a width of 28mm and a height of 105mm.

[0072] S5. Preparation of finished battery: After the battery sample is subjected to formation and capacity testing, and equipped with the necessary tooling and fixtures for testing, N2 is filled into the injection port until the internal pressure is 0.03 MPa. The battery is then sealed with a welded cover to obtain the finished battery.

[0073] Example 2

[0074] The only difference from Example 1 is that the initial internal pressure of the battery is 0.05 MPa.

[0075] Example 3

[0076] The only difference from Example 1 is that the initial internal pressure of the battery is 0.1 MPa.

[0077] Example 4

[0078] The only difference from Example 1 is that the initial internal pressure of the battery is 0.15 MPa.

[0079] Example 5

[0080] The only difference from Example 1 is that the initial internal pressure of the battery is 0.2 MPa.

[0081] Example 6

[0082] The only difference from Example 1 is that Ar2 gas is introduced, and the initial internal pressure of the battery is 0.1 MPa.

[0083] Example 7

[0084] The only difference from Example 1 is that a 70% N2 + 30% CO2 mixed gas is introduced to make the initial internal pressure of the battery 0.1 MPa.

[0085] Comparative Example 1

[0086] The only difference from Example 1 is that the initial internal pressure of the battery is -0.01 MPa.

[0087] The preparation method is the same as in Example 1, except that the steps for preparing the finished battery are as follows: after the battery is formed and tested, a micro-vacuum sealing and welding cover is used to obtain the finished battery with a vacuum degree of -0.01 MPa.

[0088] Comparative Example 2

[0089] The only difference from Example 1 is that the initial internal pressure of the battery is -0.04 MPa.

[0090] The preparation method is the same as in Example 1, except that the steps for preparing the finished battery are as follows: after the battery is formed and tested, the cover is vacuum-sealed to obtain the finished battery with a vacuum degree of -0.04 MPa.

[0091] Comparative Example 3

[0092] The only difference from Example 1 is that the initial internal pressure of the battery is 0.25 MPa.

[0093] Comparative Example 4

[0094] The only difference from Example 1 is that the initial internal pressure of the battery is 0.3 MPa.

[0095] Performance testing

[0096] 50℃ High Temperature Cycling: Explosion-proof valves were installed on the batteries in the above embodiments and comparative examples. The opening pressure of the explosion-proof valves was 0.6±0.1MPa. At 25℃, the batteries were fully charged to 4.30V with a constant current and constant voltage of 0.33C and a cutoff current of 0.02C. After resting, the batteries were discharged to 2.0V with a constant current of 0.33C. This process was repeated 3 times, and the capacity discharged in the third cycle was recorded as C0 in Ah. After resting at 50℃ for 6 hours, the batteries were charged to 4.30V with a constant current and constant voltage of 1C0 and a cutoff current of 0.05C0. After resting for 30 minutes, the batteries were discharged to 2.0V with a constant current of 0.33C0 and then rested for 30 minutes. The above process was repeated 1500 times. The internal pressure values ​​p0th, p500th, p1000t, and p500th of each battery were measured before cycling, after 500, 1000, and 1500 cycles, and recorded in Table 1.

[0097] Table 1:

[0098] p0th / MPa p500th / MPa p1000th / MPa p1500th / MPa p1500th-p500th Example 1 0.03 0.158 0.309 0.489 0.331 Example 2 0.05 0.17 0.318 0.49 0.32 Example 3 0.1 0.191 0.312 0.473 0.282 Example 4 0.15 0.221 0.333 0.48 0.259 Example 5 0.2 0.248 0.346 0.478 0.23 Example 6 0.1 0.189 0.317 0.477 0.288 Example 7 0.1 0.187 0.309 0.467 0.280 Comparative Example 1 -0.01 0.132 0.3 0.514 0.382 Comparative Example 2 -0.04 0.112 0.288 0.519 0.407 Comparative Example 3 0.25 0.299 0.398 0.531 0.232 Comparative Example 4 0.3 0.352 0.453 Open valve

[0099] As shown in Table 1, compared with Comparative Examples 1-2, the internal pressure difference of the battery in the embodiment is smaller after 1500 cycles and 500 cycles, indicating that the internal pressure growth rate of the battery in the embodiment is slower and the gas production side reaction is effectively suppressed. In contrast, due to the excessive initial internal pressure of the battery in Comparative Examples 3-4, the internal pressure of the battery is high after 1500 cycles, and the battery fails prematurely.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery, characterized in that, The initial internal pressure of the battery is T MPa, where T satisfies: 0 <T<0.25; The battery contains a second gas; or, it contains a first gas and a second gas, wherein the first gas contains at least one of nitrogen, argon, and helium; and the second gas contains at least one of oxygen, carbon monoxide, methane, ethylene, and hydrogen.

2. The battery according to claim 1, characterized in that, The gas includes a first gas and a second gas, and the volume ratio of the first gas and the second gas is 0-60.

3. The battery according to claim 2, characterized in that, The battery also includes an electrolyte, which comprises a carbonate organic solvent, and the interior of the battery contains carbon dioxide.

4. The battery according to any one of claims 1-3, characterized in that, The battery is prepared by a method including the following processes: After the battery pre-product undergoes formation and capacity testing, the casing is fixed along the direction of the electrode assembly, gas is injected to make the internal pressure of the battery pre-product T MPa, and then it is welded and packaged to obtain the finished battery product.

5. A method as claimed in claim 1 4. A method for preparing any of the batteries described above, characterized in that, Includes the following steps: The electrode assembly is placed in a housing containing an injection port. Electrolyte is injected through the injection port, and the injection port is sealed to obtain a pre-finished battery. After the battery pre-product undergoes formation and capacity testing, the housing is fixed along the direction of the electrode assembly, the liquid injection port is opened, and gas is injected to make the internal pressure of the battery pre-product T MPa. The liquid injection port is then welded and sealed to obtain the finished battery product.

6. The preparation method according to claim 5, characterized in that, Fixing the housing along the direction of the electrode assembly includes the following steps: The housing is fixed along the direction of the electrode assembly using a tooling fixture; or, the pre-assembled battery components are assembled into a battery pack or battery assembly to fix the housing.

7. A battery pack, characterized in that, Including claim 1 4. Any of the batteries described above.

8. A battery pack, characterized in that, Includes the battery pack as described in claim 7.

9. An electrical device, characterized in that, Including claim 1 4. At least one of the following: the battery as described in claim 7, the battery pack as described in claim 8.