Battery and preparation method thereof, battery pack, battery pack and electric equipment

Abstract

The invention provides a battery and a preparation method thereof, a battery pack, a battery pack and electric equipment, the initial internal pressure of the battery is TMPa, and T satisfies 0 lt; tlt; and 0.25%. According to the battery provided by the invention, the initial internal pressure is limited to be TMPa, so that the gas production side reaction of the battery is effectively inhibited, the potential safety hazards of battery expansion, leakage, thermal runaway and the like caused by the gas production side reaction can be avoided, and the use safety of the battery is improved.

Description

Technical Field

[0001] The present invention relates to the field of battery devices, and in particular to a battery and a preparation method thereof, a battery pack, a battery package, and electrical equipment. Background Art

[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 pivotal core role in today's wave of automotive electrification and intelligent energy storage.

[0003] However, due to the inherent flammable properties of the materials that make up lithium-ion batteries themselves, they are prone to thermal runaway under abuse conditions, so the safety of lithium-ion batteries has always been a focus of attention. Gas production is a common phenomenon in the charging and discharging process of lithium-ion batteries. When the battery produces gas, it will increase the occurrence of side reactions inside the battery, and at the same time, the contact between the positive and negative electrodes and the diaphragm will be poor, thereby causing the positive electrode impedance to increase, and the battery is prone to expansion and local lithium precipitation, resulting in a deterioration in the battery cycle life and rate performance. At the same time, it is also easy to cause a short circuit inside the battery, which causes a sharp increase in local temperature and causes thermal runaway. Therefore, in order to improve the safety of battery use, it is necessary to suppress the gas production reaction of lithium-ion batteries. Summary of the invention

[0004] The present invention provides a battery which produces less gas during the cycle process and thus has higher safety in use.

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

[0006] The present invention also provides a battery pack. Since the battery pack includes the above-mentioned battery, it 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. Since the battery pack includes the above-mentioned battery group, the safety problem caused by gas generation can be reduced during use.

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

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

[0010] Furthermore, the interior of the battery includes a first gas and / or a second gas, the first gas includes at least one of nitrogen, argon, and helium; 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, and a volume ratio of the first gas to the second gas is 0-60.

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

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

[0014] After the battery pre-product is subjected to formation and capacity separation treatment, the shell is fixed along the direction of the electrode assembly, gas is filled to make the internal pressure of the battery pre-product be T MPa, and welding and packaging are performed to obtain a 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 having a liquid injection port, electrolyte is injected through the liquid injection port, and the liquid injection port is sealed to obtain a battery pre-product;

[0017] After the battery pre-product is subjected to formation and capacity separation treatment, the shell is fixed along the direction of the electrode assembly, the injection port is opened, gas is filled to make the internal pressure of the battery pre-product be T MPa, and the injection port is welded and sealed to obtain a battery product.

[0018] Furthermore, fixing the shell along the direction of the electrode assembly comprises the following steps:

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

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

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

[0022] In a fifth aspect, 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 pack described in the fourth aspect.

[0023] The battery provided by the present invention limits its initial internal pressure to T MPa, so that the gas production side reaction of the battery is effectively suppressed, thereby avoiding safety hazards such as battery expansion, leakage and thermal runaway caused by the gas production side reaction, thereby improving the safety of battery use. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the application embodiments will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments in the application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the present invention, the term "and / or" describes the association relationship of associated objects, indicating that there may be three types of relationships. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural, and the character " / " generally indicates that the previously associated objects are in an "or" relationship.

[0026] In the present invention, the term "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c" can all mean: a, b, c, ab (i.e. a and b), ac, bc, or abc, where a, b, 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, and T satisfies: <T<0.25。

[0028] The initial internal pressure of the battery refers to the internal pressure of the battery after formation, capacity separation, and offline without being used. Usually, the initial internal pressure of the battery is negative pressure, and the above embodiment limits the initial internal pressure of the battery to TMPa, which can slow down the initial gas production side reaction of the battery, and then inhibit the gas production rate of the gas production side reaction of the battery. However, the initial internal pressure of the battery should not be too large. If T is greater than or equal to 0.25MPa, the initial internal pressure of the battery is too large, and the battery expands severely with the increase in the number of cycles, which leads to premature failure of the battery.

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

[0030] Among them, it can be understood that the gas inside the battery is the main reason why the initial internal pressure of the battery is positive, and the above-mentioned embodiment, by limiting the first gas and the second gas, on the one hand, helps to increase the internal pressure of the battery, thereby suppressing the gas production rate of the gas production reaction, and on the other hand, when the interior of the battery includes the second gas, in addition to increasing the internal pressure of the battery, it can also specifically suppress the gas production side reaction consistent with the second gas produced during the battery chemical reaction.

[0031] In an optional embodiment, the gas includes a first gas and a second gas, and the volume ratio of the first gas to the second gas is 0-60. Wherein, when the gas contains only the first gas (inert protective gas), the reaction space can be compressed, and the higher pressure will compress the space inside the battery, reducing the activity space of the gas molecules. This may inhibit the progress of some gas generation reactions because the reaction requires a certain space for the rearrangement and combination of molecules. When the gas also contains a second gas, according to the principle of chemical equilibrium, changes in pressure can affect the balance of the chemical reaction. For some reversible gas generation reactions, increasing the pressure may cause the reaction to move in the direction of reducing the gas volume, thereby reducing the generation of gas.

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

[0033] In an optional embodiment, the battery further comprises an electrolyte. Generally speaking, the electrolyte comprises an organic solvent, wherein the organic solvent serves as a medium for transporting ions in the electrochemical reaction, and any organic solvent known in the art for battery electrolytes may be used.

[0034] In an optional embodiment, the electrolyte includes a carbonate organic solvent, and the interior of the battery includes carbon dioxide.

[0035] CO2 is the main component of the 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 is filled into the battery, which can 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 generation rate of CO2 gas.

[0036] In some embodiments, the interior of the battery includes 60%-80% of the first gas and 20%-30% of CO 2 gas by mass.

[0037] Exemplarily, the carbonate organic solvent can be ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), or butylene carbonate (BC).

[0038] In addition to carbonate organic solvents, the above-mentioned electrolyte may also include other organic solvents, for example: at least one of 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), cyclopentane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0039] The electrolyte solution also includes electrolyte salt, wherein the electrolyte salt as a source of ions can be electrolyte salts known in the art for battery electrolytes, including but not limited to: at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonate (LiSbF6), lithium difluorophosphate (LiPF2O2), 4,5-dicyano-2-trifluoromethylimidazolium lithium (LiDTI), lithium bis(oxalyl)borate (LiBOB), lithium trifluoromethanesulfonate (LiTFS), lithium nitrate (LiNO3), and lithium fluoride (LiF).

[0040] The electrolyte may further include additives, which may be vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3-propane sultone, fluoroethylene carbonate (FEC), trifluoromethyl vinyl carbonate, dimethyl sulfate, vinyl sulfate, vinyl methyl sulfate, propylene sulfate, vinyl sulfite, succinic anhydride, biphenyl, toluene, xylene, cyclohexylbenzene, fluorobenzene, p-fluorotoluene, tert-butylbenzene, tert-amylbenzene, propylene sultone, butane sultone, methylene disulfonate, hexamethyldisilazane, heptamethyldisilazane, At least one of dimethyl methylphosphonate, diethyl ethylphosphonate, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, triphenyl phosphite, tris(trimethylsilyl) phosphate, acetonitrile (AN), malononitrile, succinonitrile (SN), glutaronitrile (GN), adiponitrile (ADN), 1,3,6-hexanetricarboxylic acid nitrile, ethylene glycol bis(propylene glycol nitrile), pentafluoroethoxycyclotriphosphazene, 1,4-dicyano-2-butene, p-methylbenzonitrile, 2-fluoroadiponitrile, 2,2-difluorosuccinonitrile, tricyanobenzene, acrylonitrile, crotononitrile, trans-butenedinitrile, and trans-hexenedinitrile.

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

[0042] The positive electrode sheet includes a current collector and a positive electrode paste disposed on at least one functional surface of the current collector, wherein the positive electrode paste includes a positive electrode active material, a conductive agent, and a binder. The present invention does not specifically limit the positive electrode active material. For example, the positive electrode active material can be selected from commonly used positive electrode active materials in the art, such as one or more of 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 selected from LiMnO2 and LiMn2O4; and lithium nickel cobalt manganese oxide can be selected from 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 0.1O2; the material of the above-mentioned current collector can be selected from any one or more of foam metal mesh, copper foil, titanium foil, tin foil, chromium foil and composite foil of the above metals; in order to improve the energy density of the battery, preferably, the paste is arranged on the two functional surfaces of the current collector in sequence; the above-mentioned 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, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate; the surface density and compaction of the above-mentioned positive electrode sheet are not specifically limited by the present invention, and the technicians can make corresponding designs according to the corresponding electrochemical system. For example, the double-sided surface density of the positive electrode sheet is 300-500g / m 2 , compacted density is 2.3~3.0g / cm 3 .

[0043] The above-mentioned negative electrode sheet includes a current collector and a negative electrode paste arranged on at least one functional surface of the current collector, wherein the negative electrode paste includes a negative electrode active material, a conductive agent and a binder, and the negative electrode active material includes one or more of graphite, hard carbon, soft carbon, silicon-based negative electrode, titanium-based material, nitride, tinide, and metallic lithium; the negative electrode current collector can be a conventional negative electrode current collector in the art, such as copper foil, etc.; the above-mentioned 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, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate.

[0044] The above-mentioned separator can be any known porous structure separator with electrochemical stability and chemical stability, for example, it can be at least one of glass fiber, non-woven fabric, polyethylene, polypropylene or polyvinylidene fluoride. The separator can be single-layer or multi-layer.

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

[0046] After the battery pre-product is subjected to formation and capacity separation treatment, the shell is fixed along the direction of the electrode assembly, the injection port is opened, gas is filled to make the internal pressure of the battery pre-product be T MPa, and the injection port is welded and sealed to obtain a battery product.

[0047] Among them, the above method injects gas before the battery is officially put into use to make the internal pressure positive, so that the chemical balance of the initial gas production side reaction of the battery is broken, thereby reducing the gas production rate of the gas production side reaction.

[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 having a liquid injection port, electrolyte is injected through the liquid injection port, and the liquid injection port is sealed to obtain a battery pre-product;

[0050] After the battery pre-product is subjected to formation and capacity separation treatment, the shell is fixed along the direction of the electrode assembly, the injection port is opened, gas is filled to make the internal pressure of the battery pre-product be T MPa, and the injection port is welded and sealed to obtain a battery product.

[0051] The preparation of the above-mentioned battery pre-finished products and the processes such as formation and capacity separation 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, and its 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 above-mentioned 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 shell is an aluminum-plastic film shell; the injection coefficient of the above-mentioned injected electrolyte is generally 2.0 to 4.5 g / Ah.

[0053] In some embodiments, the formation and capacity division treatment includes: S1, placing the battery pre-finished product in a formation cabinet, ensuring that the battery is well connected, and using a constant current constant voltage (CC-CV) mode for initial charging. 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 and the current is gradually reduced until the current drops to a set cutoff value; S2, performing initial discharge in a 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, cycling the above charge and discharge process to further activate battery performance.

[0054] In some embodiments, before the gas is filled, a process of drawing negative pressure is also included.

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

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

[0057] By fixing the shell along the direction of the electrode assembly, the probability of expansion of the battery pre-finished product due to inflation can be reduced.

[0058] In a third aspect, 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 caused by inflation, after the battery pre-product is formed and capacity-separated, before the liquid injection port is opened, the battery pre-product is first assembled into components, and then the liquid injection port is opened for inflation.

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

[0061] In a fifth aspect, 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 pack described in the fourth aspect.

[0062] It should be noted that the above-mentioned electronic equipment can be any conventional equipment that requires electricity, for example, including but not limited to computers, electric cars, air conditioners, refrigerators, washing machines, microwave ovens, printers, fax machines, etc.

[0063] The present invention is further described below in conjunction with specific embodiments:

[0064] The following test involves a method for testing the internal pressure of the battery: piercing the sealing nail with an internal pressure instrument and reading the internal pressure value of the battery.

[0065] Example 1

[0066] The present invention provides a battery, wherein the initial internal pressure of the battery is 0.03 MPa.

[0067] The preparation method comprises the following steps:

[0068] S1. Prepare a positive electrode sheet: dissolve a positive electrode active material (lithium nickel cobalt manganese oxide, wherein nickel:cobalt:manganese=7:1:2 by mole), a conductive agent CNT, a conductive agent SP and a binder PVDF in NMP to form a positive electrode slurry, apply the positive electrode slurry on both surfaces of an aluminum foil thicker than 13 μm, and obtain a positive electrode sheet including a positive electrode active layer after drying, rolling and slitting; wherein, in the positive electrode slurry, the mass ratio of the positive electrode active material, CNT, SP, PVDF and NMP is 100:18:0.5:1.6:25;

[0069] S2. Prepare negative electrode sheet: Mix and stir graphite, conductive agent, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber, water and NMP in a ratio of 100:1:1.5:3:130:3 to obtain a uniform negative electrode slurry, and evenly coat the negative electrode slurry on both surfaces of 8 mm thick conductive copper foil, dry at 110° C., and obtain a negative electrode sheet including a negative electrode active layer by slitting and die-cutting;

[0070] S3, preparing an electrolyte: consisting of a solvent, lithium hexafluorophosphate, and vinylene carbonate, wherein the solvent is a mixed solvent of vinyl carbonate and ethyl methyl 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, assembling battery pre-finished products: stacking 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, and then hot-pressing and assembling it into a soft-pack battery, vacuum-filling it according to the filling coefficient of 3.2g / Ah, sealing it, and then vacuum-sealing it after high-temperature aging, formation, aging, and volume separation to make a square aluminum shell battery with a length of 200mm, a width of 28mm, and a height of 105mm;

[0072] S5. Prepare finished battery: After the battery preparation is divided into components and equipped with the fixtures required for testing, N2 is filled into the liquid injection port until the internal pressure is 0.03MPa. Then the cover is sealed and welded to obtain a 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 gas Ar2 is filled 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 filled so that the initial internal pressure of the battery is 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 thereof refers to Example 1, with the only difference being that the steps for preparing the finished battery are as follows: after the battery is divided into capacities, a micro-vacuum sealing and welding cover is performed to obtain a finished battery, and the vacuum degree is -0.01Mpa.

[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 thereof refers to Example 1, with the only difference being that the steps for preparing the finished battery are as follows: after the battery is divided into capacities, vacuum sealing and welding the cover to obtain the finished battery, and the vacuum degree is -0.04Mpa.

[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 cycle: The batteries in the above embodiments and comparative examples are equipped with explosion-proof valves, and the opening pressure of the explosion-proof valves is 0.6±0.1MPa; at 25℃, the batteries are fully charged to 4.30V at 0.33C constant current and constant voltage, with a cut-off current of 0.02C, and then discharged to 2.0V at 0.33C constant current after being put aside, and repeated 3 times, and the third discharge capacity is recorded as C0, in Ah; after being put aside at 50℃ for 6h, the batteries are charged to 4.30V at 1C0 constant current and constant voltage, with a cut-off current of 0.05C0, and then allowed to stand for 30min, and then discharged to 2.0V at 0.33C constant current, and then allowed to stand for 30min; the above steps are cycled for 1500 times, and the internal pressure values ​​p0th, p500th, p1000t, and p500th of each battery before the cycle, after 500 cycles, 1000 cycles, and 1500 cycles are tested respectively, 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] It can be seen from Table 1 that compared with Comparative Examples 1-2, the difference in internal pressure of the battery in the embodiment after 1500 cycles and 500 cycles is smaller, indicating that the internal pressure growth rate of the battery in the embodiment is slower and the gas production side reaction is effectively suppressed. However, in Comparative Examples 3-4, due to the excessive initial internal pressure of the battery, 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, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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, and T satisfies: 0 <T<0.25。 2. The battery according to claim 1, characterized in that The interior of the battery includes 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.

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

4. The battery according to claim 3, characterized in that The battery further includes an electrolyte, the electrolyte includes a carbonate organic solvent, and the interior of the battery includes carbon dioxide.

5. The battery according to any one of claims 1 to 4, characterized in that: The battery is prepared by a method comprising the following steps: After the battery pre-product is subjected to formation and capacity separation treatment, the shell is fixed along the direction of the electrode assembly, gas is filled to make the internal pressure of the battery pre-product be T MPa, and welding and packaging are performed to obtain a battery product.

6. A method for preparing a battery according to any one of claims 1 to 5, characterized in that: The following steps are involved: The electrode assembly is placed in a housing having a liquid injection port, electrolyte is injected through the liquid injection port, and the liquid injection port is sealed to obtain a battery pre-product; After the battery pre-product is subjected to formation and capacity separation treatment, the shell is fixed along the direction of the electrode assembly, the injection port is opened, gas is filled to make the internal pressure of the battery pre-product be T MPa, and the injection port is welded and sealed to obtain a battery product.

7. The preparation method according to claim 6, characterized in that: The step of fixing the housing along the direction of the electrode assembly comprises the following steps: The shell is fixed along the direction of the electrode assembly by using a fixture; or, the battery pre-finished products are assembled into a battery pack or a battery group to fix the shell.

8. A battery pack, characterized in that: A battery comprising any one of claims 1 to 5.

9. A battery pack, characterized in that: A battery pack comprising the battery pack of claim 8.

10. An electrical device, characterized in that: It comprises at least one of the battery according to any one of claims 1 to 5, the battery pack according to claim 8, and the battery pack according to claim 9.