Battery cell, battery apparatus, energy storage apparatus, energy storage system and electric apparatus
Patent Information
- Application Number
- PCT/CN2026/070910
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-24
- Filing Date
- 2026-01-06
- Publication Date
- 2026-08-27
Smart Images
Figure CN2026070910_27082026_PF_FP_ABST
Abstract
Description
Battery cells, battery devices, energy storage devices, energy storage systems, and electrical appliances.
[0001] Cross-reference to related applications
[0002] This application is based on and claims priority to CN application number 202510202386.2 filed on February 24, 2025, the contents of which are incorporated herein by reference in their entirety. Technical Field
[0003] This application relates to the field of battery technology, and in particular to battery cells, battery devices, energy storage devices, energy storage systems, and electrical devices. Background Technology
[0004] Energy storage batteries are the core components of energy storage systems, primarily utilizing chemical reactions to store energy. Energy storage requires battery structures with large capacity, long cycle life, high safety, and high energy efficiency. However, large-capacity energy storage batteries generate significant heat and have poor heat dissipation; continuous heat accumulation can lead to safety risks such as fire and explosion. Summary of the Invention
[0005] The first aspect of this application provides a battery cell, including a casing and an electrode assembly, wherein the electrode assembly includes a positive electrode, a negative electrode, a separator, and an electrolyte; the width B, height H, and thickness T of the battery cell satisfy 350mm≤B≤650mm, 170mm≤H≤300mm, and 50mm≤T≤90mm; the negative electrode includes a current collector and a negative electrode material layer disposed on at least one side of the current collector; when the battery cell is in a fully charged state, the heat release Q of the negative electrode material layer in the immersed electrolyte satisfies: 180J / g≤Q≤600J / g; the fully charged state refers to the battery cell having a state of charge of 100%.
[0006] In some embodiments, the first negative electrode material layer includes a particulate first negative electrode active material, and the second negative electrode material layer includes a particulate second negative electrode active material. The particle size of the negative electrode active material is Dv50, and the Dv50 of the first negative electrode active material and the second negative electrode active material are each independently 9μm to 20μm, and optionally 10μm to 15μm.
[0007] In some embodiments, the first and second negative electrode material layers each comprise particulate first and second negative electrode active materials, wherein the BET specific surface area of the first and second negative electrode active materials is 1.3 m². 2 / g~3m 2 / g.
[0008] In some embodiments, the negative electrode material layer includes a first negative electrode material layer and a second negative electrode material layer, the second negative electrode material layer being disposed on the side of the first negative electrode material layer away from the current collector, the ratio of the thickness t2 of the second negative electrode material layer to the thickness t1 of the first negative electrode material layer satisfying 2 / 3≤t2 / t1≤1.5; and / or the porosity of the second negative electrode material layer is greater than the porosity of the first negative electrode material layer.
[0009] In some embodiments, the thickness t1 of the first negative electrode material layer and the thickness t2 of the second negative electrode material layer are each independently selected from 57 μm to 87 μm; and / or, the porosity of the first negative electrode material layer and the porosity of the second negative electrode material layer are each independently selected from 25% to 36%.
[0010] In some embodiments, the electrolyte contains ethylene carbonate (EC), and the mass of the ethylene carbonate accounts for 15%-25% of the mass of the electrolyte.
[0011] In some embodiments, the electrolyte contains propylene carbonate (PC), and the mass of the propylene carbonate accounts for 1%-8% of the mass of the electrolyte.
[0012] In some embodiments, the housing includes a shell, the inner and / or outer surfaces of which include a coating having thermal conductivity; in some embodiments, the coating also has heat resistance; in some embodiments, the total thickness of the coating is 1 μm to 12 μm; in some embodiments, the coating comprises one or more of the following substances: AlN, BeO, SiC, boron nitride; further, in some embodiments, the coating further comprises one or more of the following substances: Si3N4, aluminum oxide, boehmite, zirconium oxide, titanium oxide.
[0013] In some implementations, the capacity of the battery cell is greater than or equal to 500 Ah.
[0014] In some embodiments, the positive electrode includes a positive electrode material layer, the positive electrode material layer includes a positive electrode active material, the positive electrode active material includes a lithium-containing phosphate, and in some embodiments, the lithium-containing phosphate includes lithium iron phosphate.
[0015] In some implementations, the charging voltage of the battery cell is 3.65V.
[0016] In some embodiments, the immersion electrolyte comprises ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7, and LiPF6 at a concentration of 1 mol / L.
[0017] The second embodiment of this application provides a battery device including a plurality of battery cells provided in the first embodiment of this application.
[0018] The third embodiment of this application provides an energy storage device, including a plurality of battery cells provided in the first embodiment of this application or a plurality of battery devices provided in the second embodiment of this application, wherein the battery cells or the battery devices are used to store or provide electrical energy.
[0019] The fourth embodiment of this application provides an energy storage system, including a power conversion device and an energy storage device provided in the third embodiment of this application, wherein the power conversion device is used to electrically connect a power generation device and the energy storage device.
[0020] The fifth embodiment of this application provides an electrical device, including a battery cell provided in the first embodiment of this application, a battery device provided in the second embodiment of this application, an energy storage device provided in the third embodiment of this application, or an energy storage system provided in the fourth embodiment of this application, wherein the battery cell or the battery device is used to store or provide electrical energy. Attached Figure Description
[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.
[0022] Figure 1 is a schematic diagram of the width B, height H and thickness T of a battery cell according to an embodiment of this application.
[0023] Figure 2 is a schematic diagram of a battery cell according to one embodiment of this application.
[0024] Figure 3 is an exploded view of a battery cell according to an embodiment of this application shown in Figure 2.
[0025] Figure 4 is a schematic diagram of a battery module according to one embodiment of this application.
[0026] Figure 5 is a schematic diagram of a battery pack according to one embodiment of this application.
[0027] Figure 6 is an exploded view of the battery pack of one embodiment of this application shown in Figure 5.
[0028] Figure 7 is a schematic diagram of an electrical device in which a single battery cell is used as a power source according to an embodiment of this application.
[0029] The accompanying drawings are not drawn to scale.
[0030] Explanation of reference numerals in the attached diagram: 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 End cap. Detailed Implementation
[0031] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.
[0032] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the negative electrode active material and its manufacturing method, positive electrode sheet, negative electrode sheet, secondary battery, battery module, battery pack, and power-consuming 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.
[0033] 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.
[0034] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.
[0035] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.
[0036] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.
[0037] Unless otherwise specified, the terms "comprising" and "including" as used in this application are open-ended. For example, "comprising" and "including" may mean that other components not listed may also be included or contained.
[0038] Unless otherwise specified, the term "or" is inclusive in this application. For example, any of the following conditions satisfies the condition "A or B": 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).
[0039] [Battery cell]
[0040] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.
[0041] The battery cell can be a lithium-ion battery, a sodium-lithium-ion battery, a magnesium-ion battery, etc., but this application does not limit this.
[0042] Typically, a secondary battery consists of a positive electrode, a negative electrode, a separator, and an electrolyte. During charging and discharging, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing active ions to pass through. The electrolyte, also positioned between the positive and negative electrodes, mainly serves to conduct active ions.
[0043] One embodiment of this application provides a battery cell, including a casing and an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, a separator, and an electrolyte. The width B, height H, and thickness T of the battery cell satisfy 350mm≤B≤650mm, 170mm≤H≤300mm, and 50mm≤T≤90mm. The negative electrode includes a current collector and a negative electrode material layer disposed on at least one side of the current collector. When the battery cell is fully charged, the heat release Q of the negative electrode material in the immersed electrolyte satisfies 180J / g≤Q≤600J / g. The fully charged state refers to the battery cell having a state of charge of 100%.
[0044] While increasing the size of electrode components can meet the demand for high capacity, it also brings problems such as high heat generation and poor heat dissipation. Furthermore, large-size electrode components also suffer from uneven current density distribution and increased impedance. The inventors discovered that by limiting the heat generation of the negative electrode material layer under full charge to the aforementioned range, the heat generation of large electrode components can be significantly reduced, overcharge performance improved, and the safety performance of individual battery cells enhanced.
[0045] In some implementations, the width B of the battery cell satisfies 350mm≤B≤400mm, 400mm≤B≤500mm, 500mm≤B≤560mm, 560mm≤B≤600mm, or 600mm≤B≤650mm.
[0046] In some implementations, the height H of the battery cell satisfies 170mm≤H≤200mm, 200mm≤H≤250mm, or 250mm≤H≤300mm.
[0047] In some implementations, the thickness T of the battery cell satisfies 50mm≤T≤65mm, 65mm≤T≤70mm, 70mm≤T≤80mm, or 80mm≤T≤90mm.
[0048] Figure 1 is a schematic diagram of the width B, height H, and thickness T of a battery cell according to an embodiment of this application. The width B, height H, and thickness T of the battery cell can be measured using a ruler.
[0049] The aforementioned control over the size of individual battery cells helps to avoid problems such as uneven current density distribution and increased impedance caused by excessively large battery cell sizes.
[0050] In some embodiments, when the battery cell is fully charged, the heat release Q of the negative electrode material layer in the immersed electrolyte satisfies the following conditions: 180 J / g ≤ Q ≤ 200 J / g, 200 J / g ≤ Q ≤ 230 J / g, 230 J / g ≤ Q ≤ 300 J / g, 300 J / g ≤ Q ≤ 360 J / g, 360 J / g ≤ Q ≤ 400 J / g, 400 J / g ≤ Q ≤ 500 J / g, 500 J / g ≤ Q ≤ 550 J / g, or 550 J / g ≤ Q ≤ 600 J / g.
[0051] The following method can be used to measure the heat release Q of the negative electrode material layer in the immersed electrolyte:
[0052] 1) Preparation of negative electrode material layer samples: The fully charged battery cell was disassembled in a glove box, and an appropriate amount of negative electrode sheet was taken out. The negative electrode sheet was placed in DMC solvent for 2 minutes to wash away the residual electrolyte, and then dried for 8 hours. The active material layer on the electrode sheet was scraped off.
[0053] 2) Preparation of electrolyte: Ethyl carbonate and ethyl methyl carbonate are mixed in a volume ratio of 3:7, and LiPF6 is added to the mixture to form an electrolyte with a concentration of 1 mol / L.
[0054] 3) Test of heat release of negative electrode material layer: The heat release Q of negative electrode material layer is measured by differential scanning calorimetry. The measurement process is to add negative electrode material layer and electrolyte to test crucible at a mass ratio of 0.78:1, and heat from 30℃ to 450℃ at a heating rate of 5℃ / min.
[0055] The electrolyte formulation used in the above measurements is a relatively basic and conventional formulation. The results obtained by using this electrolyte to evaluate the heat release are of reference value for other electrolyte formulations. Those skilled in the art can also use other electrolyte formulations to measure Q.
[0056] In some implementations, the charging voltage of the battery cell is 3.65V.
[0057] In some embodiments, the immersion electrolyte comprises ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7, and LiPF6 at a concentration of 1 mol / L.
[0058] [Negative electrode plate]
[0059] The negative electrode sheet includes a negative current collector and a negative electrode material layer (negative electrode film layer) disposed on at least one surface of the negative current collector, wherein the negative electrode material layer includes a negative electrode active material.
[0060] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.
[0061] In some embodiments, the first negative electrode material layer includes a particulate first negative electrode active material, and the second negative electrode material layer includes a particulate second negative electrode active material. The particle size of the negative electrode active material is Dv50, and the Dv50 of the first negative electrode active material and the second negative electrode active material are each independently 9μm to 20μm (e.g., 9μm to 10μm, 10μm to 13μm, 13μm to 15μm, 15μm to 18μm or 18μm to 20μm), optionally 10μm to 15μm.
[0062] Dv50 represents the particle size corresponding to a cumulative percentage of 50%. Dv50 can be determined using a particle size analyzer-laser diffraction method; specifically, it can be measured according to standard GB / T 19077-2016.
[0063] In some embodiments, the first and second negative electrode material layers each comprise particulate first and second negative electrode active materials, and the BET specific surface area of each of the first and second negative electrode active materials is independently 1.3 m². 2 / g~3m 2 / g, for example 1.3m 2 / g~1.5m 2 / g, 1.5m 2 / g~2m 2 / g、2m 2 / g~2.1m 2 / g、2.1m 2 / g~2.9m 2 / g, 2.9m 2 / g~3m 2 / g.
[0064] The BET specific surface area of the negative electrode active material can be measured by referring to the following method: determined by the specific surface area meter-static volumetric method according to the standard GB / T19587-2017. Specifically, according to the embodiments of this application, a flow method gas adsorption type specific surface area measuring device can be used for measurement.
[0065] By selecting the particle size and BET specific surface area of the negative electrode active materials included in the first and second negative electrode material layers, the contact area between graphite and electrolyte can be adjusted, thereby controlling the heat generation of the side reactions between graphite and electrolyte, and thus controlling the heat release Q of the negative electrode material layer.
[0066] In some embodiments, the first and second anode material layers contain the same anode active material, such as graphite. This can be identical graphite or graphite with different particle sizes and / or BET specific surface areas. If the anode active material is identical, the difference in porosity between the first and second anode material layers can be achieved by adjusting the formulation of the first and second anode material layers, thereby improving battery kinetics.
[0067] In some embodiments, the negative electrode material layer includes a first negative electrode material layer and a second negative electrode material layer, the second negative electrode material layer being disposed on the side of the first negative electrode material layer away from the current collector, and the ratio of the thickness t2 of the second negative electrode material layer to the thickness t1 of the first negative electrode material layer satisfying 2 / 3≤t2 / t1≤1.5; in some embodiments, the porosity of the second negative electrode material layer is greater than the porosity of the first negative electrode material layer.
[0068] In some embodiments, the porosity of the two layers can be adjusted by modifying the formulations of the coating slurry for the first and second negative electrode layers. For example, the coating slurry for the second negative electrode layer can have a higher conductive carbon content and a lower graphite content compared to the coating slurry for the first negative electrode layer. After coating and cold pressing, the compaction density of the second negative electrode layer will be slightly lower than that of the first negative electrode layer, thereby increasing the porosity of the second negative electrode layer.
[0069] In some embodiments, the ratio of the thickness t2 of the second negative electrode material layer to the thickness t1 of the first negative electrode material layer satisfies 2 / 3≤t2 / t1≤1 or 1≤t2 / t1≤1.5.
[0070] In some embodiments, the thickness t1 of the first negative electrode material layer and the thickness t2 of the second negative electrode material layer are each independently selected from 57μm to 87μm, for example 57μm to 60μm, 60μm to 65μm, 65μm to 70μm, 70μm to 72μm, 72μm to 80μm or 80μm to 87μm.
[0071] In some embodiments, the porosity of the first negative electrode material layer and the porosity of the second negative electrode material layer are each independently selected from 25% to 36%, for example 25% to 26%, 26% to 28%, 28% to 30%, 30% to 32%, 32% to 34%, or 34% to 36%.
[0072] The interfacial impedance of a single-layer coating is greater than that of a multi-layer coating. Using a multi-layer negative electrode material has several advantages. First, it reduces the binder content in each layer, lowering the interfacial impedance. Second, it improves the uniformity of binder distribution within the electrode, enhancing current density. Furthermore, the tiered porosity distribution (wider at the top, denser at the bottom) facilitates thorough electrolyte wetting. Since the electrolyte conducts lithium ions, this design accelerates ion transport on the negative electrode surface, ultimately improving cell dynamics and extending cycle life. Therefore, this negative electrode design is particularly suitable for large-size, high-capacity electrode assemblies.
[0073] The thickness of the first negative electrode material layer and the thickness of the second negative electrode material layer can be measured using the following methods:
[0074] Take a cross-section of the negative electrode sheet and observe it using tomographic SEM. A clear boundary line between the two coating layers can be seen. Using the boundary line as a baseline, measure the thickness from the boundary line to the current collector surface, which is the thickness of the first active layer; measure the thickness from the boundary line to the upper surface of the electrode sheet, which is the thickness of the second active layer.
[0075] The porosity of the negative electrode sheet can be measured using the following methods:
[0076] A cross-section of the negative electrode sheet was taken, and the double-layer coating structure of the negative electrode sheet was observed using tomographic SEM. A cross-sectional SEM image of a randomly selected field of view was taken, ensuring it contained the complete first and second active layers. The total area S1 of the first active layer and the total area R1 occupied by the first active material in the first active layer were measured. The porosity of the first active layer was defined as (1-R1 / S1)×100%. The total area S2 of the second active layer and the total area R2 occupied by the second active material in the second active layer were measured. The porosity of the second active layer was defined as (1-R2 / S2)×100%.
[0077] 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 material substrate and a metal layer formed on at least one surface of the polymer material 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 material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
[0078] 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. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials 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.
[0079] In some embodiments, the negative electrode film layer may optionally include a binder. As an example, 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).
[0080] In some embodiments, the negative electrode film may optionally include a conductive agent. As an example, 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.
[0081] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).
[0082] 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.
[0083] [Electrolytes]
[0084] 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.
[0085] In some embodiments, the electrolyte is liquid and includes an electrolyte salt and a solvent.
[0086] 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.
[0087] In some embodiments, the solvent may be selected from at least one of ethylene carbonate (ethylene carbonate), propylene 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.
[0088] In some embodiments, the electrolyte contains ethylene carbonate (EC) at a mass percentage of 15%-25% (e.g., 15%-18%, 18%-20%, or 20%-25%) of the electrolyte. Ethylene carbonate has a high dielectric constant and good lithium salt dissolution and electrolysis capabilities, but its viscosity is high. Adding too much can easily degrade the electrolyte's conductivity and affect its wetting ability. For large-size, high-capacity battery cells, electrolyte wetting is more difficult compared to smaller cells. Adding ethylene carbonate within the aforementioned mass percentage range allows the high dielectric constant and good lithium salt dissolution and electrolysis capabilities to be utilized, while also ensuring sufficient electrolyte conductivity and good wetting ability.
[0089] In some embodiments, the electrolyte contains propylene carbonate (PC) at a mass percentage of 1%-8% (e.g., 1%-2%, 2%-4%, 4%-6%, or 6%-8%) of the electrolyte. Propylene carbonate has a high dielectric constant and a low freezing point; its inclusion in the electrolyte is beneficial for improving the low-temperature conductivity of the electrolyte, thereby improving the battery's low-temperature performance. However, excessive addition can lead to the carbonation of the negative electrode active material along with lithium ions, resulting in the stripping of the negative electrode active material and deteriorating the battery's cycle life. Adding propylene carbonate within the aforementioned mass percentage range can improve the battery's low-temperature performance without adversely affecting its cycle life.
[0090] In some embodiments, the electrolyte may optionally include additives. As examples, 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.
[0091] [shell]
[0092] The battery cell of this application may include a casing. The casing may be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum-plastic film, etc. In some embodiments, the casing may be a sealed structure or a non-sealed structure. As an example, when the casing is a non-sealed structure, the casing serves to protect the electrode assembly, and a sealing bag is included between the casing and the electrode assembly for encapsulating the electrode assembly and electrolyte. Specifically, the sealing bag may be a bag-shaped insulating component or an aluminum-plastic film. When the casing is a sealed structure, it is used to encapsulate components such as the electrode assembly and electrolyte.
[0093] In some embodiments, the housing includes a casing, the inner and / or outer surfaces of which include a coating that has thermal conductivity. Providing a thermally conductive coating on the inner and / or outer surfaces of the casing can facilitate heat dissipation from within the battery cell, thereby improving heat dissipation capacity.
[0094] Furthermore, the casing may also have heat resistance to prevent it from melting and breaking through due to heat, thereby improving the safety performance of the battery cell.
[0095] In some embodiments, the total thickness of the coating is 1 μm to 12 μm (e.g., 1 μm to 4 μm, 4 μm to 8 μm, or 8 μm to 12 μm).
[0096] The coating material can be selected to possess both thermal conductivity and heat resistance, or additional heat-resistant materials can be added to the coating. In some embodiments, the coating comprises one or more of the following substances: aluminum nitride (AlN), BeO, SiC, and boron nitride, to obtain thermal conductivity. SiC and boron nitride, in particular, possess both thermal conductivity and heat resistance. In some embodiments, the coating further comprises one or more of aluminum oxide, boehmite, zirconium oxide, titanium oxide, and Si3N4 to obtain heat resistance.
[0097] In some embodiments, the inner surface of the housing includes a coating with a thickness of 1 μm to 4 μm.
[0098] In some embodiments, the outer surface of the housing includes a coating with a thickness of 1 μm to 4 μm.
[0099] In some embodiments, both the inner and outer surfaces of the housing include coatings, the thickness of which is independently 1 μm to 4 μm.
[0100] In some embodiments, the inner surface coating comprises aluminum nitride and boehmite.
[0101] In some embodiments, the outer surface coating comprises aluminum nitride and boehmite.
[0102] The coating thickness on the inner or outer surface of the housing can be measured using the following methods:
[0103] Take a portion of the shell, smooth the cross-section, place it under a CCD microscope, observe the coating on the inner and outer surfaces of the cut surface, and measure the thickness of the coating.
[0104] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. This application does not have any particular limitations.
[0105] In some embodiments, the housing includes an end cap and a housing, the housing having an opening, and the end cap covering the opening. The housing may have one or more openings. The end cap may also have one or more.
[0106] In some embodiments, at least one electrode terminal is provided on the housing, and the electrode terminal is electrically connected to the tab. The electrode terminal can be directly connected to the tab, or it can be indirectly connected to the tab through a current collector. The electrode terminal can be provided on the end cap or on the housing.
[0107] In some embodiments, a pressure relief mechanism is provided on the casing. The pressure relief mechanism is used to release the internal gas of the battery cell.
[0108] As an example, the internal pressure or temperature of a battery cell is actuated to release the internal pressure or temperature when it reaches a predetermined threshold. When the internal pressure or temperature of the battery cell reaches the predetermined threshold, the pressure relief mechanism is activated or a weak structure in the pressure relief mechanism is broken, thereby creating an opening or channel for the internal pressure or temperature to be released. The threshold design varies depending on the design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell.
[0109] As an example, the pressure relief mechanism can be integrally molded with the housing.
[0110] As an example, the pressure relief mechanism can also be separately installed and connected to the housing.
[0111] The term "actuation" as used in this application refers to the activation or actuation of the pressure relief mechanism to a certain state, thereby releasing the internal pressure and temperature of the battery cell. The actions of the pressure relief mechanism may include, but are not limited to: movement of components within the mechanism to form an exhaust channel, rupture, breakage, tearing, or opening of at least a portion of the mechanism, etc. When the pressure relief mechanism is activated, the high-temperature, high-pressure substances inside the battery cell are discharged as waste from the activated portion. This method allows for pressure and temperature relief of the battery cell under controllable pressure or temperature, thereby preventing potentially more serious accidents.
[0112] In some embodiments, when the housing is a non-sealed structure, the pressure relief mechanism can be configured as a through hole for venting gas inside the battery cell.
[0113] The emissions from battery cells mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.
[0114] [Positive electrode plate]
[0115] In some embodiments, the positive electrode sheet includes a positive electrode material layer, the positive electrode material layer includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate. Optionally, the lithium-containing phosphate includes lithium iron phosphate (e.g., soft carbon-coated lithium iron phosphate).
[0116] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector. As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.
[0117] As an example, the positive current collector can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, pure metals, alloys, or surface-treated metals can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).
[0118] In some embodiments, the battery cell is a lithium-ion battery, and the positive electrode active material can be a positive electrode active material known in the art for lithium-ion batteries. The positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, 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 phosphate include, but are not limited to, at least one of 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 iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (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 0.05 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by doping or coating, or other modification methods, based on the aforementioned substances.
[0119] In the examples of positive electrode active materials in this application, the molar content of oxygen is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of oxygen will fluctuate.
[0120] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.
[0121] 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.
[0122] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, a positive electrode active material is filled and / or deposited within the foamed metal.
[0123] 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.
[0124] [Isolation membrane]
[0125] 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.
[0126] 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.
[0127] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.
[0128] This application enables large-size battery cells to have high capacity while generating low heat, improving overcharge performance and enhancing battery cell safety. In some embodiments, the capacity of the battery cell is greater than or equal to 500Ah, for example, 500Ah to 640Ah, 640Ah to 730Ah, or 730Ah to 1100Ah.
[0129] The capacity of a single battery cell can be tested using the following methods:
[0130] At 25℃, the capacity of the battery cells was tested on a charge-discharge meter. First, the battery cells were discharged to 2.5V at a rate of 0.25P and left to stand for 10 minutes. Then, they were charged to 3.65V at a rate of 0.25P and left to stand for 30 minutes. Finally, they were discharged to 2.5V at a rate of 0.25P. The discharge capacity recorded was the capacity of the battery cells.
[0131] Figure 2 shows a square-structured battery cell 5 as an example.
[0132] In some embodiments, referring to FIG3, the housing may include a housing 51 and an end cap 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 end cap 53 can be closed by covering the opening to seal the receiving cavity. A positive electrode sheet, a negative electrode sheet, and a separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. The number of electrode assemblies 52 contained in a single battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.
[0133] [Battery Device]
[0134] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.
[0135] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.
[0136] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.
[0137] Figure 4 shows a battery module 4 as an example. Referring to Figure 4, in the battery module 4, multiple battery cells 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other arbitrary way. Furthermore, the multiple battery cells 5 can be fixed in place using fasteners.
[0138] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.
[0139] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.
[0140] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.
[0141] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.
[0142] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.
[0143] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.
[0144] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.
[0145] Figures 5 and 6 show a battery pack 1 as an example. Referring to Figures 5 and 6, 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 box 2 and a lower box 3, with the upper box 2 covering the lower box 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.
[0146] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.
[0147] Figure 7 shows an example of an electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the individual battery cells, a battery pack or battery module can be used. [Example]
[0148] 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.
[0149] General testing methods:
[0150] Test the following parameters using the method described above:
[0151] The particle size and BET specific surface area of the negative electrode active material, the width B, height H and thickness T of the battery cell, the heat release of the negative electrode material layer, the porosity of the negative electrode sheet, the capacity of the battery cell, the coating thickness of the inner or outer surface of the casing, the thickness of the first negative electrode material layer and the thickness of the second negative electrode material layer.
[0152] Overcharge test method
[0153] The overcharge test was conducted in accordance with the overcharge test standard in GBT 36276-2023, and the highest temperature of the large surface of the battery cell during the overcharge test was recorded.
[0154] Battery cycle life test method
[0155] At 25℃, the battery was charged at 1C to 3.65V, then charged at a constant voltage to 0.05C, allowed to stand for 10 minutes, and then discharged at 1C to 2.5V. The first discharge capacity was recorded as C0. The charge-discharge cycle test was performed according to the above procedure, and the capacity retention rate after the cycles was calculated. The capacity retention rate after the 25℃ cycle is: Capacity retention rate after the nth cycle = (Discharge capacity after the nth cycle / Discharge capacity C0 of the first cycle) * 100%.
[0156] Battery Low Temperature Fast Charging Performance Test
[0157] At 25℃, the battery is charged at 1C to 3.65V, then charged at a constant voltage to 0.05C, and then left to stand for 10 minutes. It is then discharged at 1C to 2.5V, and the discharge capacity is recorded as D0. The battery is then placed at -10℃ for charging. It is charged at 0.5D0 to 3.65V, and the charging capacity is recorded as D1. It is then discharged at 1D0 to 2.5V, left to stand for 30 minutes, and then charged at 2D0 to 3.65V, and the charging capacity is recorded as D2. The low-temperature fast charging capacity retention rate = D2 / D1.
[0158] Example 1
[0159] Preparation of the positive electrode sheet
[0160] Lithium iron phosphate (LiFePO4), conductive agent Super P, and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 97:1:2. N-methylpyrrolidone was added as a solvent and stirred until homogeneous to obtain a positive electrode slurry. The positive electrode slurry was uniformly coated on both sides of the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain a positive electrode sheet.
[0161] Preparation of the negative electrode sheet
[0162] (1) The first active material graphite, conductive agent Super-P, dispersant CMC and binder SBR are mixed in an appropriate amount of deionized water at a mass ratio of 96.4:0.4:1.0:2.2 to form a uniform negative electrode slurry A1.
[0163] (2) The second active material graphite, conductive agent Super-P, dispersant CMC and binder SBR are mixed in an appropriate amount of deionized water at a mass ratio of 96.0:0.7:1.1:2.2 to form a uniform negative electrode slurry A2.
[0164] (3) The negative electrode paste A1 is coated on the negative electrode current collector copper foil, and the negative electrode paste A2 is coated on A1. After drying, cold pressing, electrode tab die cutting and slitting, a double-coated negative electrode sheet is obtained.
[0165] Preparation of Electrolyte
[0166] In an argon-filled glove box (water content <10ppm, oxygen content <1ppm), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and propylene carbonate (PC) were mixed in a mass ratio of 18:78:4 to obtain an electrolyte solvent. Then, fully dried lithium salt LiPF6 was added to the above solvent and mixed to prepare an electrolyte with a lithium salt concentration of 1mol / L.
[0167]
Isolation Film
[0168] Polyethylene film is used as the separation membrane.
[0169] [Preparation of battery cells]
[0170] The positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, with the separator positioned between the positive and negative electrode sheets for isolation. After winding, a bare electrode assembly is obtained. Positive and negative tabs are then welded on to obtain the electrode assembly. The electrode assembly is then assembled into a casing, and the prepared electrolyte is injected. The battery is then encapsulated, allowed to stand, formed, shaped, and its capacity tested to finally produce a lithium-ion battery.
Claims
1. A battery cell, comprising a casing and an electrode assembly, wherein the electrode assembly comprises a positive electrode, a negative electrode, a separator, and an electrolyte; the width B, height H, and thickness T of the battery cell satisfy 350mm≤B≤650mm, 170mm≤H≤300mm, and 50mm≤T≤90mm; the negative electrode comprises a current collector and a negative electrode material layer disposed on at least one side of the current collector, wherein, when the battery cell is in a fully charged state, the heat release Q of the negative electrode material layer in the immersed electrolyte satisfies: 180J / g≤Q≤600J / g; the fully charged state refers to the battery cell having a state of charge of 100%.
2. The battery cell according to claim 1, wherein, The first negative electrode material layer includes a particulate first negative electrode active material, and the second negative electrode material layer includes a particulate second negative electrode active material. The particle size of the negative electrode active material is Dv50. The Dv50 of the first negative electrode active material and the second negative electrode active material are each independently 9μm to 20μm, and can be selected as 10μm to 15μm.
3. The battery cell according to claim 1 or 2, wherein, The first and second negative electrode material layers each comprise particulate first and second negative electrode active materials, and the BET specific surface area of the first and second negative electrode active materials is 1.3 m². 2 / g~3m 2 / g.
4. The battery cell according to any one of claims 1-3, wherein, The negative electrode material layer includes a first negative electrode material layer and a second negative electrode material layer. The second negative electrode material layer is disposed on the side of the first negative electrode material layer away from the current collector. The ratio of the thickness t2 of the second negative electrode material layer to the thickness t1 of the first negative electrode material layer satisfies 2 / 3≤t2 / t1≤1.5; and / or the porosity of the second negative electrode material layer is greater than that of the first negative electrode material layer.
5. The battery cell according to any one of claims 1-4, wherein, The thickness t1 of the first negative electrode material layer and the thickness t2 of the second negative electrode material layer are each independently selected from 57 μm to 87 μm; and / or, the porosity of the first negative electrode material layer and the porosity of the second negative electrode material layer are each independently selected from 25% to 36%.
6. The battery cell according to any one of claims 1-5, wherein, The electrolyte contains ethylene carbonate (EC), and the mass of the ethylene carbonate accounts for 15%-25% of the mass of the electrolyte.
7. The battery cell according to any one of claims 1-6, wherein, The electrolyte contains propylene carbonate (PC), and the mass of propylene carbonate accounts for 1%-8% of the mass of the electrolyte.
8. The battery cell according to any one of claims 1-7, wherein, The housing includes a shell, the inner surface and / or outer surface of which includes a coating that has a thermally conductive function; Optionally, the coating also has heat resistance; Optionally, the total thickness of the coating is 1 μm to 12 μm; Optionally, the coating comprises one or more of the following substances: AlN, BeO, SiC, and boron nitride; further optionally, the coating also comprises one or more of the following substances: Si3N4, aluminum oxide, boehmite, zirconium oxide, and titanium oxide.
9. The battery cell according to any one of claims 1-8, wherein, The capacity of the battery cell is greater than or equal to 500Ah.
10. The battery cell according to any one of claims 1-9, wherein, The positive electrode sheet includes a positive electrode material layer, the positive electrode material layer includes a positive electrode active material, the positive electrode active material includes a lithium phosphate, and optionally, the lithium phosphate includes lithium iron phosphate.
11. The battery cell according to any one of claims 1-10, wherein, The charging voltage of the battery cell is 3.65V.
12. The battery cell according to any one of claims 1-11, wherein, The electrolyte used for immersion comprises ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7, and LiPF6 at a concentration of 1 mol / L.
13. A battery device comprising a plurality of battery cells according to any one of claims 1-10.
14. An energy storage device comprising a plurality of battery cells according to any one of claims 1-10 or a plurality of battery devices according to claim 11, wherein the battery cells or the battery devices are used to store or provide electrical energy.
15. An energy storage system comprising a power conversion device and an energy storage device according to claim 12, wherein the power conversion device is used to electrically connect a power generation device and the energy storage device.
16. An electrical device comprising a battery cell according to any one of claims 1-10, a battery device according to claim 11, an energy storage device according to claim 12, or an energy storage system according to claim 13, wherein the battery cell or the battery device is used to store or provide electrical energy.