A secondary battery, a battery module, a battery pack, and an electric device

Abstract

The present application provides a secondary battery, a battery module, a battery pack, and a power consuming device. The secondary battery of the present application contains a carbon dioxide gas adsorbent including a closed ring-shaped solid amine compound having no hydroxyl group, the closed ring-shaped solid amine compound being a closed ring-shaped amine compound having a primary amine or a secondary amine and having a carbon atom number of 3 to 40, the secondary battery having a water content of 50 to 500 ppm, and a mass ratio of the water content of the secondary battery to a content of the closed ring-shaped solid amine compound having no hydroxyl group in the secondary battery being 0.16 or more. The carbon dioxide gas adsorbent adsorbs carbon dioxide generated inside the secondary battery, thereby reducing the internal pressure of the secondary battery, reducing the internal resistance growth rate, improving the capacity retention rate, and further improving the safety performance of the secondary battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a secondary battery, battery module, battery pack, and electrical device. Background Technology

[0002] In recent years, with the increasingly wide application of secondary batteries, they have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other fields. Due to the significant development of secondary batteries, higher requirements have been placed on their energy density, cycle performance, and safety performance.

[0003] Secondary batteries suffer from gas production issues; excessive gas production leads to cell swelling, increased impedance, and shortened lifespan. The gases generated inside secondary batteries mainly consist of CO2, CO, CH4, C2H4, C2H6, and H2, with CO2 being the most abundant. Therefore, selectively absorbing the main component of the gas produced by the battery cell (i.e., CO2) is an effective solution. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a secondary battery that can selectively absorb the main component of the gas produced by the cell (i.e., CO2) and solve the problems of high gas production pressure, increased internal resistance, and deterioration of power and capacity in lithium-ion batteries.

[0005] To achieve the above objectives, this application provides a secondary battery, a battery module, a battery pack, and an electrical device.

[0006] The first aspect of this application provides a secondary battery comprising a carbon dioxide gas adsorbent, the carbon dioxide gas adsorbent comprising a hydroxyl-free closed-ring solid amine compound, the hydroxyl-free closed-ring solid amine compound being a closed-ring amine compound containing a primary or secondary amine with 3 to 40 carbon atoms, the secondary battery having a water content of 50 to 500 ppm, and the mass ratio of the water content of the secondary battery to the content of the hydroxyl-free closed-ring solid amine compound in the secondary battery being 0.16 or more.

[0007] Therefore, it is possible to adsorb carbon dioxide generated inside the secondary battery, reduce the internal pressure of gas production in the secondary battery, reduce the rate of increase of battery internal resistance, improve the capacity retention rate, and further improve the safety performance of the secondary battery.

[0008] In any embodiment, the hydroxyl-free closed-ring solid amine compound may be a closed-ring amine compound containing a primary or secondary amine having 3 to 10 carbon atoms, and may be further selected from at least one of piperazine, homopiperazine, trans-1,4-diaminocyclohexane, and 1,4,7-triazacyclononane compounds.

[0009] In any embodiment, the carbon dioxide gas adsorbent further contains hydroxide. By containing hydroxide in the carbon dioxide gas adsorbent, a small amount of H2O can be generated by the reaction of the hydroxide. The generated H2O directly participates in the adsorption cycle reaction of the adsorbent, thereby slowing down the saturation rate of the adsorbent. On the other hand, since the generated H2O is only produced and utilized in the carbon dioxide gas adsorbent system, it will not have any other impact on the performance of the secondary battery.

[0010] In any embodiment, the hydroxide is selected from at least one of sodium hydroxide, calcium hydroxide, and lithium hydroxide.

[0011] In any embodiment, the content of the hydroxide is 24–159 ppm, optionally 48–96 ppm. By controlling the content of the hydroxide within the above range, the internal pressure of the secondary battery can be further reduced without causing other adverse effects on the secondary battery.

[0012] In some embodiments, the molar ratio of the hydroxyl-free closed-ring solid amine compound to the hydroxide content is 10:3 to 10:20, optionally 10:10. By controlling the molar ratio of the hydroxyl-free closed-ring solid amine compound to the hydroxide content within the above range, the internal pressure of gas generation in the secondary battery can be further reduced.

[0013] In some embodiments, the content of the hydroxyl-free closed-ring solid amine compound in the secondary battery is 86–421 ppm. Controlling the content of the hydroxyl-free closed-ring solid amine compound within the above range can reduce the internal pressure of gas generation in the secondary battery without affecting the energy density of the secondary battery.

[0014] In some embodiments, the carbon dioxide gas adsorbent is encapsulated in a porous, breathable membrane and placed in the top sealing space of the secondary battery. The volume percentage of the carbon dioxide gas adsorbent in the top sealing space is 0.3%-1.8%, optionally 0.6%-1.5%. This encapsulation method can effectively absorb the emitted carbon dioxide gas and reduce the internal pressure of the secondary battery.

[0015] In some embodiments, the carbon dioxide gas adsorbent is coated inside the casing of the secondary battery, and the coating thickness is 2-10 mm, optionally 3-8 mm. This method increases the contact area between the carbon dioxide gas adsorbent and the carbon dioxide gas, thereby achieving a better adsorption effect.

[0016] In some embodiments, the carbon dioxide gas adsorbent is added to the electrolyte. The above method is simple to operate and the preparation process is straightforward.

[0017] A second aspect of this application provides a battery module, including the secondary battery of the first aspect of this application.

[0018] A third aspect of this application provides a battery pack that includes the battery module of the second aspect of this application.

[0019] A fourth aspect of this application provides an electrical device comprising at least one selected from the secondary battery of the first aspect of this application, the battery module of the second aspect of this application, or the battery pack of the fifth aspect of this application.

[0020] The battery module, battery pack, and power device of this application include the secondary battery of the first aspect of this application, and therefore have at least the same or similar technical effects as the aforementioned secondary battery. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a secondary battery according to one embodiment of this application.

[0022] Figure 2 yes Figure 1 An exploded view of a secondary battery according to one embodiment of this application is shown.

[0023] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application.

[0024] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0025] Figure 5 yes Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown.

[0026] Figure 6 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Secondary battery; 51 Casing; 52 Electrode assembly; 53 Top cover assembly Detailed Implementation

[0029] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the secondary battery, battery module, battery pack, and electrical device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0030] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0032] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0033] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0034] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0035] Secondary batteries

[0036] In one embodiment of this application, a secondary battery is proposed to adsorb carbon dioxide generated inside the secondary battery, thereby reducing the internal pressure of the secondary battery, reducing the rate of increase in internal resistance, improving the capacity retention rate, and further improving the safety performance of the secondary battery.

[0037] This application provides a secondary battery comprising a carbon dioxide gas adsorbent, wherein the carbon dioxide gas adsorbent comprises a hydroxyl-free closed-ring solid amine compound, wherein the hydroxyl-free closed-ring solid amine compound is a closed-ring amine compound containing a primary or secondary amine with 3 to 40 carbon atoms, the secondary battery has a water content of 50 to 500 ppm, and the mass ratio of the water content of the secondary battery to the content of the hydroxyl-free closed-ring solid amine compound in the secondary battery is 0.16 or higher.

[0038] Although the mechanism is not yet clear, the inventors of this application have unexpectedly discovered that by including a carbon dioxide gas adsorbent in the secondary battery and controlling the water content of the secondary battery, and by keeping the mass ratio of the water content of the secondary battery to the content of the hydroxyl-free closed-ring solid amine compound in the secondary battery within a certain range, the gas production internal pressure of the secondary battery can be improved.

[0039] The inventors of this application speculate that, taking a hydroxyl-free closed-ring solid amine compound containing a primary amine as an example, the reaction pathway for the absorption of CO2 by the hydroxyl-free closed-ring solid amine compound is to carry out a closed-ring reaction according to the following formulas (1) and (2), thereby inducing the recycling of the hydroxyl-free closed-ring solid amine compound.

[0040]

[0041]

[0042] The hydroxyl-free, closed-ring solid amine compound itself can react rapidly with CO2 to form a zwitterionic compound in a stoichiometric ratio of 2:1. Under the condition that the water content of the secondary battery is 50-500 ppm, the zwitterionic compound reacts with water molecules to generate bicarbonate and the hydroxyl-free, closed-ring solid amine compound. That is, the hydroxyl-free, closed-ring solid amine compound can also participate in the adsorption of CO2, with the stoichiometric ratio optimized to 1:1.

[0043] Furthermore, the hydroxyl-free closed-ring solid amine compound, lacking hydroxyl groups, reduces its protonation reaction and the likelihood of water molecule formation. This hydroxyl-free closed-ring solid amine compound also exhibits high stability due to its closed-ring structure, minimizing its reaction with the electrolyte. This allows for the adsorption of carbon dioxide generated inside the secondary battery, reducing the internal pressure of gas production, decreasing the rate of increase in internal resistance, improving capacity retention, and further enhancing the safety performance of the secondary battery.

[0044] In some embodiments, the hydroxyl-free closed-ring solid amine compound may be a closed-ring amine compound containing a primary or secondary amine having 3 to 10 carbon atoms, and may be further selected from at least one of the following compounds: piperazine (Formula 1), homopiperazine (Formula 2), trans-1,4-diaminocyclohexane (Formula 3), and 1,4,7-triazacyclononane (Formula 4).

[0045]

[0046] In some embodiments, the carbon dioxide gas adsorbent also contains hydroxide. During gas adsorption, zwitterionic compounds form a passivation layer on the surface of a hydroxyl-free closed-ring solid amine compound. This passivation layer causes equation (1) to reach saturation after a certain period. By including hydroxide in the carbon dioxide gas adsorbent, H2O can be introduced through the reaction of the hydroxide, thereby participating in the reaction of equation (2) above, slowing down the gas adsorption saturation rate caused by the passivation layer, and promoting the reduction of the internal pressure of gas generation in the secondary battery. On the other hand, since the H2O generated by the hydroxide can be generated only in the carbon dioxide gas adsorbent system and directly utilized, it will not have other adverse effects on the performance of the secondary battery.

[0047] In some embodiments, the hydroxide is selected from at least one of sodium hydroxide, calcium hydroxide, and lithium hydroxide.

[0048] In some embodiments, the hydroxide content is 24–159 ppm, optionally 48–96 ppm. By controlling the hydroxide content within the above range, the internal pressure of the secondary battery can be further reduced without causing other adverse effects on the secondary battery.

[0049] In some embodiments, the molar ratio of the hydroxyl-free closed-ring solid amine compound to the hydroxide content is 10:3 to 10:20, optionally 10:10. By controlling the molar ratio of the hydroxyl-free closed-ring solid amine compound to the hydroxide content within the above range, the internal pressure of gas generation in the secondary battery can be further reduced.

[0050] In some embodiments, the content of the hydroxyl-free closed-ring solid amine compound in the secondary battery is 86–421 ppm. Controlling the content of the hydroxyl-free closed-ring solid amine compound within the above range can reduce the internal pressure of gas generation in the secondary battery without affecting the energy density of the secondary battery.

[0051] In some embodiments, the carbon dioxide gas adsorbent is encapsulated in a porous, breathable membrane and placed in the top sealing space of the secondary battery. The volume percentage of the carbon dioxide gas adsorbent in the top sealing space is 0.3%-1.8%, optionally 0.6%-1.5%. The top sealing space is the space between the internal winding structure (JR) of the battery and the top cover, and the top sealing space must be positioned to avoid the liquid injection hole. This encapsulation method can effectively absorb the emitted carbon dioxide gas, further reducing the internal pressure of the secondary battery.

[0052] In some embodiments, the carbon dioxide gas adsorbent is coated inside the casing of the secondary battery, and the coating thickness is 2-10 mm, optionally 3-8 mm. This method increases the contact area between the carbon dioxide gas adsorbent and the carbon dioxide gas, thereby achieving a better adsorption effect.

[0053] In some embodiments, the carbon dioxide gas adsorbent is added to the electrolyte. The above method is simple to operate and the preparation process is straightforward.

[0054] In addition, the secondary battery, battery module, battery pack and power device of this application will be described below with appropriate reference to the accompanying drawings.

[0055] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0056] [Positive electrode plate]

[0057] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including the positive electrode active material of the first aspect of this application.

[0058] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0059] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0060] In some embodiments, the positive electrode active material may be a known battery positive electrode active material. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0061] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0062] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0063] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0064] [Negative electrode plate]

[0065] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0066] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0067] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0068] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0069] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0070] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0071] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0072] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0073] [Electrolytes]

[0074] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0075] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0076] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0077] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0078] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0079] [Isolation membrane]

[0080] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0081] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0082] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0083] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0084] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0085] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 This is an example of a square-structured secondary battery 5.

[0086] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 can be placed over the opening to close the receiving cavity. A positive electrode, a negative electrode, and a separator can be formed into an electrode assembly 52 using a winding or stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The secondary battery 5 may contain one or more electrode assemblies 52, which can be selected by those skilled in the art according to specific practical needs.

[0087] In some implementations, the secondary batteries can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0088] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple secondary batteries 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple secondary batteries 5 can be fixed in place using fasteners.

[0089] Optionally, the battery module 4 may also include a housing with a receiving space in which a plurality of secondary batteries 5 are received.

[0090] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0091] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0092] In addition, this application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0093] As the electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0094] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0095] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0096] Example

[0097] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0098] Example 1

[0099] 1) Preparation of positive electrode sheet

[0100] LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2, PVDF binder, conductive carbon black, carbon nanotube (CNT) conductive paste, and Li2CO3 were mixed in a mass ratio of 28.5:66.5:1.1:2.3:0.4:1.2. NMP solvent was added, and the mixture was stirred in a vacuum mixer until a homogeneous and transparent system was obtained to obtain the positive electrode paste. The positive electrode paste was uniformly coated onto the positive electrode current collector aluminum foil, dried at room temperature, transferred to an oven for drying, and then cold-pressed and slit to obtain the positive electrode sheet.

[0101] 2) Preparation of negative electrode sheet

[0102] Artificial graphite (anode active material), sodium carboxymethyl cellulose (CMC) (thickener), and styrene-butadiene rubber (SBR) (binder) (mass ratio 98:1:1) are mixed with deionized water (solvent) and stirred in a vacuum mixer to obtain anode slurry. The anode slurry is then uniformly coated onto copper foil (anode current collector). After being dried at room temperature, the coating is transferred to an oven for drying, followed by cold pressing and slitting to obtain the anode sheet.

[0103] 3) Separating membrane

[0104] A 9μm thick polypropylene (PP) film (model A273, supplied by Celgard) was used.

[0105] 4) Preparation of electrolyte

[0106] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed thoroughly in a volume ratio of 1:1:1 to obtain an organic solvent. 1 mol / L LiPF6 was dissolved in the above organic solvent to obtain the electrolyte.

[0107] 5) Preparation of lithium-ion secondary batteries

[0108] The positive electrode, separator, and negative electrode are stacked sequentially, with the separator acting as a barrier between the positive and negative electrodes. They are then wound into a square bare cell, and tabs are welded on. The bare cell is then installed into a casing. After the cell is installed, the top cover is welded on. First, the cell is vacuum-dried in a vacuum drying oven at 110℃±5℃, with a vacuum level of ≤90Pa, for 29 hours (hrs). After cooling to room temperature, 10 mmol of piperazine is encapsulated in an oleophobic polypropylene (PP) bare film bag (length * width ≈ 1 / 3 of the top cover length * top cover width) and placed in the top sealing space of the cell (away from the electrolyte injection port to minimize interaction with the electrolyte). After welding the top cover, electrolyte is injected and the cell is sealed. Following standing, formation, and shaping processes, a lithium-ion secondary battery is obtained. The secondary battery contains 50 ppm of water and 298 ppm of piperazine.

[0109] Example of PP film oil-repellent treatment: After immersing the PP film in polytetrafluoroethylene (PTFE) emulsion, it is taken out and dried.

[0110] Examples 2-24 and Comparative Examples 1-3

[0111] Except for changing the type and content of carbon dioxide gas adsorbent as shown in Table 1 and changing the water content of the secondary battery by adjusting the vacuum drying time, lithium-ion secondary batteries were prepared in the same manner as in Example 1. Comparative Example 3 served as a blank group, in which no carbon dioxide gas adsorbent was added.

[0112] The lithium-ion secondary batteries prepared in the above embodiments and comparative examples were tested for battery performance using the following methods, and the results are shown in Table 2.

[0113] (1) Gas generation internal pressure (MPa) of secondary battery @ 20D test

[0114] A self-made gas-generating battery cell with a gas tube and an internal pressure gauge was prepared. The battery cell was placed in a high-low temperature chamber, and the test temperature was set to 70℃ for 20 days. The internal pressure gauge can monitor and record the internal gas pressure value inside the battery cell in real time.

[0115] (2) Test on the improvement ratio of gas production in secondary batteries

[0116] By comparing the gas production internal pressure values ​​of the examples (or comparative examples) and the control group, the internal pressure improvement ratio of each example (or comparative example) can be obtained.

[0117] Improvement ratio = (1 - gas production internal pressure value of the example (or comparative example) / gas production internal pressure value of the comparative blank group) × 100%.

[0118] (3) Test of the internal resistance growth rate of secondary batteries

[0119] At room temperature, the battery cell is first fully charged to the upper limit voltage of 4.2V in a high and low temperature chamber. Then, the state of charge (SOC) of the battery cell is adjusted to a specified 50% SOC, and the initial voltage value V0 is recorded. The charge / discharge machine is set with a constant current of 1C (C = rated capacity of the battery cell 205Ah), a lower limit voltage of 2.8V, and a pulse discharge time of 30s. When the discharge time meets 30s, the voltage at the end of the discharge is recorded as Vt. Internal resistance = (V0 - Vt) / 1C (mohm). The internal resistance values ​​are recorded before the start of storage and after 20 days of storage, and the growth rate of internal resistance can be calculated.

[0120] Internal resistance growth rate (%) = Internal resistance after 20 days of storage / Initial internal resistance × 100%.

[0121] (4) Capacity retention test of secondary batteries

[0122] Set the temperature to room temperature in a high and low temperature chamber, fully charge the battery cell to the upper limit voltage of 4.2V, then discharge it with a constant current of 1 / 3C to the lower limit voltage of 2.8V, and record the initial capacity value. After 20 days of storage, record the capacity value again, and the battery's capacity retention rate can be calculated.

[0123] Capacity retention rate (%) = Capacity after 20 days of storage / Initial capacity × 100%.

[0124] (5) Water content test of secondary batteries

[0125] The battery cells prepared in the examples (or comparative examples) were placed in a vacuum drying oven, and the drying temperature was set to 110℃±5℃ and the vacuum degree to ≤90Pa. The battery cells were then removed from the vacuum drying oven, placed in a test tube bottle, and the water content value was read.

[0126] Table 1: Relevant parameters of Examples 1-24 and Comparative Examples 1-3

[0127]

[0128] Table 2: Performance test results of Examples 1-24 and Comparative Examples 1-3

[0129]

[0130] As shown in Tables 1 and 2, in Examples 1 to 24, which contain hydroxyl-free closed-ring solid amine compounds, by controlling the water content of the secondary battery and the mass ratio of the water content to the content of the hydroxyl-free closed-ring solid amine compounds within a specified range, carbon dioxide generated inside the secondary battery is adsorbed, reducing the internal pressure of gas generation in the secondary battery. At the same time, the rate of increase in battery internal resistance is reduced, the improvement ratio and capacity retention rate of the battery are increased, and the safety performance of the secondary battery is further improved.

[0131] Examples 25-30

[0132] The secondary batteries in Examples 25-30 are prepared using a method similar to that in Example 1, but the position of the carbon dioxide gas adsorbent within the secondary battery is adjusted. In Examples 25-30, the carbon dioxide gas adsorbent is coated inside the cell casing.

[0133] Coating process: Prepare an aluminum shell for use as the battery cell housing. Prepare a piperazine film in the laboratory and coat it onto the inside of the battery cell housing. Other battery cell manufacturing processes are the same as normal battery cell operation procedures. Specifically, the piperazine film is prepared by processing 90wt% piperazine and 10wt% PVDF binder into a slurry with 30wt% NMP (70% solids content), and then coating it onto the inside of the housing, with a coating area of ​​2*2cm. 2 Then it is dried in a drying oven.

[0134] Table 3: Relevant parameters and performance test results of Examples 25-30

[0135]

[0136] As shown in Table 3, applying hydroxyl-free closed-ring solid amine compounds to the inside of the secondary battery casing for 25-30 cycles, while controlling the coating thickness, also yielded good results.

[0137] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A secondary battery, characterized in that, The invention comprises a carbon dioxide gas adsorbent, wherein the carbon dioxide gas adsorbent includes a hydroxyl-free closed-ring solid amine compound, wherein the hydroxyl-free closed-ring solid amine compound is a closed-ring amine compound containing a primary or secondary amine with 3 to 40 carbon atoms. The water content of the secondary battery is greater than or equal to 50 ppm and less than or equal to 300 ppm. The ratio of water content to the content of the hydroxyl-free closed-ring solid amine compound in the secondary battery is 0.16-1.

01. The carbon dioxide gas adsorbent further comprises a hydroxide, wherein the molar ratio of the hydroxyl-free closed-ring solid amine compound to the hydroxide is greater than 10:20 and less than 10:

3.

2. The secondary battery according to claim 1, characterized in that, The hydroxyl-free closed-ring solid amine compound is selected from at least one of piperazine, homopiperazine, trans-1,4-diaminocyclohexane, and 1,4,7-triazacyclononane.

3. The secondary battery according to claim 1, characterized in that, The hydroxide is selected from at least one of sodium hydroxide, calcium hydroxide, and lithium hydroxide.

4. The secondary battery according to claim 1, characterized in that, The content of the hydroxide is greater than 24 and less than or equal to 159 ppm.

5. The secondary battery according to claim 4, characterized in that, The content of the hydroxide is 48–96 ppm.

6. The secondary battery according to claim 1, characterized in that, The molar ratio of the hydroxyl-free closed-ring solid amine compound to the hydroxide is 1:

1.

7. The secondary battery according to claim 1, characterized in that, The content of the hydroxyl-free closed-ring solid amine compound in the secondary battery is 86-421 ppm.

8. The secondary battery according to claim 1, characterized in that, The carbon dioxide gas adsorbent is encapsulated in a porous, breathable membrane and placed in the top sealing space of the secondary battery. The volume percentage of the carbon dioxide gas adsorbent in the top sealing space is 0.3%-1.8%.

9. The secondary battery according to claim 8, characterized in that, The carbon dioxide gas adsorbent accounts for 0.6%-1.5% of the volume of the top-sealed space.

10. The secondary battery according to claim 1, characterized in that, The carbon dioxide gas adsorbent is coated inside the casing of the secondary battery, and the coating thickness is 2-10 mm.

11. The secondary battery according to claim 10, characterized in that, The coating thickness is 3-8 mm.

12. The secondary battery according to claim 1, characterized in that, The carbon dioxide gas adsorbent is added to the electrolyte.

13. A battery module, characterized in that, Includes the secondary battery as described in any one of claims 1-12.

14. A battery pack, characterized in that, Includes the battery module as described in claim 13.

15. An electrical appliance, characterized in that, It includes at least one selected from the secondary battery of any one of claims 1-12, the battery module of claim 13, or the battery pack of claim 14.

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