Current collector, battery pole piece, battery cell and battery pack body

Abstract

The invention discloses a current collector, a battery pole piece, a battery cell and a battery pack body, relates to the technical field of batteries, and aims to solve the problem of temperature difference between battery cells in the battery pack body and between parts in the battery cells. The current collector comprises a first metal layer, a middle layer and a second metal layer which are sequentially stacked. And the material of the middle layer comprises a binding material and a negative temperature coefficient thermistor material.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a current collector, a battery pole piece, a battery cell and a battery package. Background Art

[0002] When the battery cells are assembled into a battery pack, under different operating conditions, due to the influence of various factors such as differences in heat conduction between the internal battery cells, uneven heat dissipation conditions, and different arrangements of the battery cells, there will be temperature differences between the battery cells and between the various parts inside the battery cells, which will cause uneven current density distribution between the battery cells and between the various parts inside the battery cells, resulting in different speeds of chemical reactions between the battery cells and between the various parts inside the battery cells, and ultimately leading to inconsistent life decay between different battery cells; in addition, during long-term use, due to inconsistent life decay between the battery cells, the voltage difference between the battery cells will gradually increase. When the voltage difference exceeds a certain threshold, the system will trigger an alarm, causing trouble to the user. Summary of the Invention

[0003] The purpose of this application is to provide a current collector, battery pole piece, battery cell and battery package, aiming to solve the problem of temperature difference between battery cells in the battery package and between various parts inside the battery cell, thereby improving the life of the battery package.

[0004] To achieve the above objectives, this application adopts the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides a current collector comprising: a first metal layer, an intermediate layer, and a second metal layer stacked in sequence. The intermediate layer comprises a bonding material and a negative temperature coefficient thermistor material.

[0006] In the material of the middle layer of the current collector provided in the embodiment of the present application, the resistance value of the negative temperature coefficient thermistor material decreases as the temperature increases (i.e., the NTC effect). By introducing this material into the material of the middle layer of the current collector, its characteristics can be used to balance the temperature difference. When the temperature of a certain part is too high, the resistance of the negative temperature coefficient thermistor material in that area decreases, thereby increasing the heat dissipation in that area, which helps to reduce the temperature. On the contrary, the area with lower temperature has higher resistance and relatively less heat dissipation, which helps to reduce the temperature from dropping further. Therefore, through the distribution of the negative temperature coefficient thermistor material, the self-regulation and balance of the internal temperature of the current collector can be achieved, and the consistency of the temperature at different positions on the current collector can be improved. In the material of the middle layer, the bonding material can ensure close contact and effective heat conduction between the middle layer and the first metal layer and the second metal layer, which helps to quickly conduct heat from the high temperature area to the low temperature area, thereby further improving the temperature consistency at different positions on the current collector.

[0007] Improving the temperature consistency at different locations on the current collector can improve the temperature consistency at different locations on the battery electrode. The temperature consistency at different locations on the battery electrode in the battery cell ensures temperature consistency between various parts of the battery cell and between the cells, making the chemical reaction rates of various parts of the battery cell and between the cells similar, thereby avoiding uneven current density and impedance distribution between various parts of the battery cell and between the cells due to temperature differences, making the aging rates of the cells similar, and improving the consistency of the battery cell life attenuation; moreover, the temperature consistency at different locations on the battery electrode can also make the thermal stress distribution inside the battery cell more uniform, reducing the risk of thermal stress concentration and battery cell rupture due to temperature differences.

[0008] In some embodiments, the negative temperature coefficient thermistor material includes: a metal oxide.

[0009] In some embodiments, the metal oxide includes at least one of cobalt oxide, nickel oxide, manganese oxide, yttrium oxide, aluminum oxide, zirconium oxide, and titanium oxide.

[0010] In some embodiments, the ratio of the sum of the mass of cobalt oxide, nickel oxide, and manganese oxide to the total mass of the metal oxides is in a range of 0.66 to 0.95.

[0011] In some embodiments, the metal oxide includes the following materials in parts by weight: 31 to 40 parts cobalt oxide, 10 to 15 parts nickel oxide, 25 to 40 parts manganese oxide, 1 to 2 parts yttrium oxide, 1 to 5 parts aluminum oxide, 1 to 2 parts zirconium oxide, and 1 to 2 parts titanium oxide.

[0012] In some embodiments, the ratio of the mass of the negative temperature coefficient thermistor material to the total mass of the intermediate layer material is in a range of 0.7 to 0.9.

[0013] In some embodiments, the bonding material includes at least one of an ethoxy polymer, a vinylidene fluoride polymer, a silane polymer, an ether polymer, and an ester polymer.

[0014] In some embodiments, the size of the intermediate layer in the first direction ranges from 1 μm to 5 μm; the first direction is the direction in which the first metal layer, the intermediate layer, and the second metal layer are stacked in sequence.

[0015] In a second aspect, an embodiment of the present application provides a battery pole piece, the battery pole piece comprising: a current collector according to any one of the above embodiments and an electrode active material. The electrode active material is located on at least one side of the current collector.

[0016] In a third aspect, embodiments of the present application provide a battery electrode sheet comprising a current collector and a material layer. The material layer is disposed on at least one side of the current collector. The material layer comprises an electrode active material, a binder material, and a negative temperature coefficient thermistor material.

[0017] In some embodiments, the material layer includes the following materials in parts by mass: 85 to 96 parts of electrode active material, 1 to 6 parts of negative temperature coefficient thermistor material, and 1 to 4 parts of bonding material.

[0018] In some embodiments, the material of the material layer further includes: a conductive agent.

[0019] In some embodiments, the ratio of the mass of the electrode active material to the mass of the conductive agent ranges from 17 to 48.

[0020] In a fourth aspect, an embodiment of the present application provides a battery cell, comprising: a battery cell housing and a battery electrode according to any one of the above embodiments. The battery electrode is disposed in the battery cell housing.

[0021] It can be understood that the beneficial effects that can be achieved by the battery cell provided by the above embodiments of the present application can refer to the beneficial effects of the current collector mentioned above, and will not be repeated here.

[0022] In a fifth aspect, embodiments of the present application provide a battery package comprising: a plurality of battery cells and a battery package housing. The plurality of battery cells are disposed within the battery package housing. At least one of the plurality of battery cells is a battery cell described in the above embodiments.

[0023] It can be understood that the beneficial effects that can be achieved by the battery pack provided by the above embodiments of the present application can refer to the beneficial effects of the current collector described above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1 A schematic diagram of a battery pack is provided for an embodiment of the present application;

[0026] Figure 2 A schematic diagram of a current collector is provided for an embodiment of the present application;

[0027] Figure 3 Schematic diagram of the current collector in some embodiments of the present application;

[0028] Figure 4 Schematic diagrams of current collectors in some other embodiments of the present application;

[0029] Figure 5 A schematic diagram of a battery electrode is provided for an embodiment of the present application;

[0030] Figure 6 A schematic diagram of another battery electrode is provided for an embodiment of the present application.

[0031] Figure numerals: 10 - current collector, 1 - first metal layer, 2 - intermediate layer, 3 - second metal layer, 4 - adhesive material layer, 5 - electrode active material, 6 - material layer, 20 - battery pole piece, 100 - battery package, 200 - battery package shell, 300 - battery cell. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0033] In the description of this application, it should be understood that the terms "upper," "lower," "left," "right," "front," "back," "inner," "outer," and the like, indicating directions or positional relationships, are based on the directions or relative positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction. Therefore, they should not be construed as limitations on this application. Unless otherwise specified, the above-mentioned directionality descriptions may be flexibly set in actual application, provided that the relative positional relationships shown in the accompanying drawings are met.

[0034] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0035] In the embodiments of the present application, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, article, or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of other identical elements in the process, article, or device comprising the element.

[0036] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0037] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0038] like Figure 1 As shown, an embodiment of the present application provides a battery package 100. The battery package 100 includes: a plurality of battery cells 300 and a battery package shell 200. The plurality of battery cells 300 are disposed in the battery package shell 200.

[0039] The battery cell 300 is the core component of the battery package 100, responsible for storing and releasing electrical energy. The battery package casing 200 protects the battery cell 300, providing physical protection from external impact and damage and supporting the heat dissipation and insulation structure within the battery package 100.

[0040] When the battery cells 300 are assembled into a battery pack 100 (including a battery module), under different operating conditions, due to the influence of various factors such as the difference in heat conduction between the internal battery cells 300, the uneven heat dissipation conditions, and the different arrangements of the battery cells 300, the temperature differences between the battery cells 300 and between the various parts inside the battery cells 300 will cause uneven current density distribution between the battery cells 300 and between the various parts inside the battery cells 300, resulting in different speeds of chemical reactions between the battery cells 300 and between the various parts inside the battery cells 300, ultimately leading to inconsistent life attenuation between different battery cells 300; in addition, during long-term use, due to the inconsistent life attenuation between the battery cells 300, the voltage difference between the battery cells 300 will gradually increase. When the voltage difference exceeds a certain threshold, the system will trigger an alarm, causing trouble to the user.

[0041] To this end, an embodiment of the present application provides a battery cell 300. The battery cell 300 includes a battery cell housing and a battery electrode. The battery electrode is disposed in the battery cell 300 housing.

[0042] The battery cell 300 shell is the external protective structure of the battery cell 300, usually made of metal or alloy materials, with good mechanical strength and corrosion resistance. Its main function is to protect the battery electrodes and internal electrolyte from the influence of the external physical and chemical environment, while providing structural support for the battery cell 300.

[0043] The battery electrode is the core component of the battery cell 300. It is composed of positive and negative electrode materials and is coated on a current collector. The electrolyte forms an ion channel between the positive and negative electrode materials, enabling the storage and release of electrical energy. Multiple battery electrode sheets and other components (such as separators and electrolytes) are assembled to form the battery cell 300.

[0044] The temperatures at different positions on the battery electrodes in the above-mentioned battery cell 300 are consistent. In this way, the temperatures between various parts inside the battery cell 300 and between the battery cells 300 can be ensured to be consistent, so that the chemical reaction rates of various parts inside the battery cell 300 and between the battery cells 300 are similar, thereby avoiding uneven current density and impedance distribution among various parts inside the battery cell 300 and between the battery cells 300 due to temperature differences, making the aging rates of the battery cells 300 similar, so as to improve the consistency of the life attenuation of the battery cells 300; moreover, the consistent temperatures at different positions on the battery electrodes can also make the thermal stress distribution inside the battery cell 300 more uniform, reducing the risk of thermal stress concentration and battery cell rupture due to temperature differences.

[0045] In some embodiments, at least one of the plurality of battery cells 300 of the battery pack 100 is the aforementioned battery cell 300 .

[0046] Therefore, in order to improve the temperature consistency at different positions on the battery electrode, considering that the current collector is a key component in the battery electrode, as a bridge connecting the positive and negative poles with the outside world, it mainly plays the role of conduction, current collection and heat dissipation; improving the temperature consistency at different positions on the current collector can improve the temperature consistency at different positions on the battery electrode.

[0047] Based on this, Figure 2 As shown, an embodiment of the present application provides a current collector 10, which includes: a first metal layer 1, an intermediate layer 2, and a second metal layer 3 stacked in sequence. The material of the intermediate layer 2 includes: a bonding material and a negative temperature coefficient thermistor material.

[0048] The main functions of the first metal layer 1 and the second metal layer 3 are to carry positive and negative electrode materials, and to collect and output the current generated by the active materials during the charge and discharge process, or to input the current to the active materials.

[0049] In some exemplary embodiments, the first metal layer 1 and the second metal layer 3 may be metal foils.

[0050] Illustratively, the first metal layer 1 may be any one of copper foil and aluminum foil.

[0051] Illustratively, the second metal layer 3 may be any one of copper foil and aluminum foil.

[0052] Here, the first metal layer 1 and the second metal layer 3 may be the same or different.

[0053] The main function of the intermediate layer 2 is to balance the temperature difference at different locations on the current collector 10 and improve the temperature consistency at different locations on the current collector 10 .

[0054] Among them, the resistance value of the negative temperature coefficient thermistor material in the material of the intermediate layer 2 decreases as the temperature increases (i.e., the NTC effect). By introducing this material into the material of the intermediate layer 2 of the current collector 10, its characteristics can be used to balance the temperature difference. When the temperature of a certain part is too high, the resistance of the negative temperature coefficient thermistor material in that area decreases, thereby increasing the heat dissipation in that area, which helps to reduce the temperature. On the contrary, the area with a lower temperature has a higher resistance and relatively less heat dissipation, which helps to reduce further temperature drops. Therefore, through the distribution of the negative temperature coefficient thermistor material, the self-regulation and balance of the internal temperature of the current collector 10 can be achieved, and the consistency of the temperature at different locations on the current collector 10 can be improved.

[0055] Among the materials of the intermediate layer 2, the adhesive material can ensure close contact and effective heat conduction between the intermediate layer 2 and the first metal layer 1 and the second metal layer 3, which helps to quickly conduct heat from the high-temperature area to the low-temperature area, thereby further improving the temperature consistency at different positions on the current collector 10.

[0056] Compared to Figure 3 The single current collector 10 shown is composed of a single metal layer, and relative to Figure 4 The composite current collector 10 shown is composed of a first metal layer 1, a second metal layer 3 and an intermediate adhesive material layer 4. A current collector 10 of the present application has obvious advantages in improving the temperature consistency of different positions on the current collector 10.

[0057] In some embodiments, the negative temperature coefficient thermistor material includes: a metal oxide.

[0058] As the temperature rises, some electrons in the metal oxide that were originally bound around atoms or molecules will gain enough energy to break free and become free electrons (for n-type semiconductors) or holes (for p-type semiconductors). The increase in free electrons or holes will increase the conductivity of the material, thereby reducing the resistance value. In other words, metal oxides have a good NTC effect; and metal oxides have good thermal conductivity, which helps to quickly conduct heat from high-temperature areas to low-temperature areas. In the current collector 10, when the intermediate layer 2 contains metal oxide, the metal oxide can act as an effective thermal bridge to promote the uniform distribution of heat in the current collector 10, reduce the occurrence of local overheating or overcooling, and improve the temperature consistency at different positions on the current collector 10.

[0059] In some embodiments, the metal oxide includes at least one of cobalt oxide, nickel oxide, manganese oxide, yttrium oxide, aluminum oxide, zirconium oxide, and titanium oxide.

[0060] The above-mentioned cobalt oxide, nickel oxide, manganese oxide, yttrium oxide, aluminum oxide, zirconium oxide and titanium oxide not only have the characteristics of negative temperature coefficient thermistor materials that can improve the temperature consistency at different positions on the current collector 10, but also have other characteristics such as high sensitivity, good stability, fast response and long life, thereby improving the performance of the current collector 10.

[0061] In some embodiments, the ratio of the sum of the mass of cobalt oxide, nickel oxide, and manganese oxide to the total mass of the metal oxides is in a range of 0.66 to 0.95.

[0062] For example, the ratio of the sum of the mass of cobalt oxide, nickel oxide and manganese oxide to the total mass of the metal oxides may be 0.66, 0.75, 0.85 or 0.95, etc., which is not limited here.

[0063] By setting the ratio of the sum of the mass of the above-mentioned cobalt oxide, the mass of the nickel oxide and the mass of the manganese oxide to the total mass of the metal oxide in the range of 0.66 to 0.95, that is, cobalt oxide, nickel oxide and manganese oxide occupy a major proportion in the metal oxide, since cobalt oxide, nickel oxide and manganese oxide are more sensitive to temperature changes, the material of the intermediate layer 2 can exhibit a stronger NTC effect, so that the current collector 10 can respond faster and adjust its temperature distribution when the temperature changes, thereby improving the consistency of the temperature at different positions on the current collector 10.

[0064] In addition, cobalt oxide, nickel oxide and manganese oxide have good chemical stability and thermal stability, are well compatible with the first metal layer 1 and the second metal layer 3, can maintain stable performance over a wider temperature range, are not prone to phase change or decomposition, and help ensure the long-term stable operation of the current collector 10 in high or low temperature environments.

[0065] In some embodiments, the metal oxide includes the following materials in parts by weight: 31 to 40 parts cobalt oxide, 10 to 15 parts nickel oxide, 25 to 40 parts manganese oxide, 1 to 2 parts yttrium oxide, 1 to 5 parts aluminum oxide, 1 to 2 parts zirconium oxide, and 1 to 2 parts titanium oxide.

[0066] By further setting the mass fractions of the above-mentioned metal oxide components and cooperating with each other, the temperature consistency at different positions on the current collector 10 can be further improved.

[0067] In some embodiments, the ratio of the mass of the negative temperature coefficient thermistor material to the total mass of the intermediate layer material is in a range of 0.7 to 0.9.

[0068] For example, the ratio of the mass of the negative temperature coefficient thermistor material to the total mass of the intermediate layer material may be 0.7, 0.75, 0.80, 0.85, or 0.90, etc., which is not limited here.

[0069] By setting the ratio of the mass of the negative temperature coefficient thermistor material to the total mass of the intermediate layer material in the range of 0.7 to 0.9, the adhesive material can effectively fill the small gaps between the negative temperature coefficient thermistor material and the first metal layer 1 and the second metal layer 3, forming a strong mechanical bond, ensuring that the intermediate layer 2 is not easily peeled off or detached from the first metal layer 1 and the second metal layer 3 under the influence of external factors such as temperature changes and mechanical stress. It can also ensure that the negative temperature coefficient thermistor material dominates the intermediate layer 2, thereby improving the significance and accuracy of the NTC effect of the current collector 10, and ensuring that heat is effectively transferred between the negative temperature coefficient thermistor material and the first metal layer 1 and the second metal layer 3, reducing thermal resistance, improving the response speed of the intermediate layer 2 to temperature differences, and further improving the temperature consistency at different locations on the current collector 10.

[0070] In some embodiments, the bonding material includes at least one of an ethoxy polymer, a vinylidene fluoride polymer, a silane polymer, an ether polymer, and an ester polymer.

[0071] Ethoxylated polymers generally have good adhesion and flexibility, bonding well to metal surfaces and providing some resilience to mechanical stresses caused by temperature changes.

[0072] Vinylidene fluoride-based polymers (such as polyvinylidene fluoride PVDF) have excellent chemical resistance, heat resistance and weather resistance, and are suitable for use in high temperature, humid or corrosive environments.

[0073] Silane-based polymers have excellent high-temperature resistance and good adhesion, making them particularly suitable for applications requiring high-temperature stability. They also have good weather resistance and aging resistance.

[0074] Ether polymers have good flexibility and low-temperature resistance, can maintain good physical properties in low-temperature environments, and also have good processing properties, which facilitates coating and molding during the manufacturing process.

[0075] Ester polymers have good mechanical properties and oil resistance and are suitable for applications that require resistance to grease or solvent corrosion.

[0076] At least one of the above-mentioned ethoxy polymers, vinyl fluoride polymers, silane polymers, ether polymers and ester polymers is used as the material of the intermediate layer 2, which can achieve better bonding between the intermediate layer 2 and the first metal layer 1 and the second metal layer 3, and suitable bonding materials can also be selected according to different working conditions.

[0077] In some embodiments, as Figure 2 As shown, the size D of the intermediate layer 2 in the first direction Y is in the range of 1 μm to 5 μm. The first direction Y is the direction in which the first metal layer 1 , the intermediate layer 2 and the second metal layer 3 are stacked in sequence.

[0078] For example, the dimension D of the intermediate layer 2 in the first direction Y may be 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, etc., which is not limited here.

[0079] By setting the size D of the intermediate layer 2 in the first direction Y to be in the range of 1μm to 5μm, it helps to transfer heat faster between the negative temperature coefficient thermistor material and the first metal layer 1 and the second metal layer 3; it also helps to improve the contact between the intermediate layer 2, the first metal layer 1 and the second metal layer 3, reducing the material falling when the intermediate layer 2 is larger, and reducing the bonding strength when the intermediate layer 2 is smaller, increasing the risk of peeling or falling off under mechanical stress, thereby improving the stability of the current collector 10.

[0080] The embodiment of the present application provides a battery electrode 20. Figure 5 As shown, the battery electrode 20 includes: the current collector 10 of any one of the above embodiments and an electrode active material 5. The electrode active material 5 is located on at least one side of the current collector 10.

[0081] Particles (e.g., electrons) migrate within the electrode active material 5 and between the electrode active material 5 and the electrolyte interface to form an electric current. By placing the electrode active material 5 on at least one side of the current collector 10, the negative temperature coefficient thermistor material has less influence on the movement of particles within the electrode active material. Furthermore, good contact between the current collector 10 and the electrode active material 5 reduces thermal resistance, making it easier for heat to transfer from the electrode active material 5 to the current collector 10. Therefore, placing the current collector 10 according to any of the above embodiments on a battery electrode can improve the temperature consistency at different locations on the battery electrode 20.

[0082] The embodiment of the present application provides another battery electrode 20. Figure 6 As shown, the battery electrode 20 includes: a current collector 10 and a material layer 6. The material layer 6 is provided on at least one side of the current collector 10. The material of the material layer 6 includes: an electrode active material, a binder material and a negative temperature coefficient thermistor material.

[0083] Illustratively, the current collector 10 may be any one of the current collectors 10 in any of the above embodiments.

[0084] For example, the current collector 10 may also be a single current collector 10 (eg Figure 3 As shown), composite current collector 10 (as Figure 4 Any one of the ones shown).

[0085] It can be understood that by introducing a negative temperature coefficient thermistor material into the material layer 6, the temperature difference can be balanced by utilizing the characteristic that its resistance value decreases as the temperature increases. When the temperature of a certain part is too high, the resistance of the negative temperature coefficient thermistor material in that area decreases, thereby increasing the heat dissipation in that area, which helps to reduce the temperature. On the contrary, the area with a lower temperature has a higher resistance and relatively less heat dissipation, which helps to reduce the temperature from dropping further. Therefore, through the distribution of the negative temperature coefficient thermistor material, the internal temperature of the current collector 10 can be self-regulated and balanced, and the temperature consistency of different positions on the current collector 10 can be improved. The adhesive material can ensure close contact and effective heat conduction between the material layer 6 and the current collector 10, which helps to quickly conduct heat from the high temperature area to the low temperature area, thereby further improving the temperature consistency of different positions on the battery electrode 20.

[0086] In some embodiments, the material layer includes the following materials in the following weight proportions: 85 to 96 parts of electrode active material, 1 to 6 parts of negative temperature coefficient thermistor material, and 1 to 4 parts of bonding material.

[0087] For example, the mass fraction of the electrode active material can be 85, 87, 90, 93 or 96, etc., which is not limited here.

[0088] For example, the mass fraction of the negative temperature coefficient thermistor material can be 1, 2, 3, 4, 5 or 6, etc., which is not limited here.

[0089] For example, the mass fraction of the bonding material may be 1, 2, 3 or 4, etc., which is not limited here.

[0090] By configuring the material layer to include the following materials in proportion by mass: 85 to 96 parts of electrode active material, 1 to 6 parts of negative temperature coefficient thermistor material, and 1 to 4 parts of adhesive material, the transmission of electrons is ensured, the influence of the negative temperature coefficient thermistor material and the adhesive material on the electrons is reduced, the conductive performance of the material layer 6 can be improved, and the overall temperature consistency on the battery electrode 20 can be improved.

[0091] In some embodiments, the material of the material layer further includes: a conductive agent.

[0092] Conductive agents (such as carbon black, carbon nanotubes, and graphene) are added to improve the conductivity of the electrode material. These agents can form a conductive network within the electrode material, promoting electron transport and reducing the effects of the negative temperature coefficient thermistor material and adhesive on electrons. This can enhance the conductivity of the material layer 6 and improve overall temperature consistency across the battery electrode 20.

[0093] In some embodiments, the ratio of the mass of the electrode active material to the mass of the conductive agent ranges from 17 to 48.

[0094] For example, the ratio of the mass of the conductive agent to the mass of the electrode active material may be 17, 25, 33, 38, 43, or 48, etc., which is not limited here.

[0095] By setting the ratio of the mass of the electrode active material to the mass of the conductive agent in the range of 17 to 48, the transmission of electrons can be further promoted, the influence of the negative temperature coefficient thermistor material and the bonding material on the electrons can be reduced, the conductivity of the material layer 6 can be improved, and the overall temperature consistency on the battery electrode 20 can be improved.

[0096] The following describes the method for preparing the battery cell in further detail using specific embodiments as examples.

[0097] Example 1

[0098] The method for preparing the battery cell 300 of Example 1 includes the following steps:

[0099] Step (1): preparing a mixed slurry of a bonding material and a metal oxide; wherein the ratio of the mass of the metal oxide to the sum of the mass of the bonding material and the mass of the metal oxide is in the range of 0.7; the metal oxide comprises the following materials in parts by mass: 31 parts by mass of CoO, 10 parts by mass of NiO, 25 parts by mass of MnO, 1 part by mass of Y2O3, 1 part by mass of Al2O3, 1 part by mass of ZrO2, and 1 part by mass of TiO2.

[0100] Step (2): The mixed slurry of the prepared adhesive material and metal oxide is coated between the copper foil and the aluminum foil to obtain an intermediate layer 2, forming a current collector 10, wherein the thickness of the intermediate layer 2 is 3 μm.

[0101] Step (3): coating the positive and negative electrode slurries on the current collector 10 to form the electrode sheet 20.

[0102] Step (4): The electrode plate 20 is prepared into a battery cell 300 through processes such as baking, rolling, slitting, and assembly.

[0103] Example 2

[0104] The method for preparing the battery cell 300 of Example 2 includes the following steps:

[0105] Step (1): preparing a bonding material and a metal oxide slurry; wherein the ratio of the mass of the metal oxide to the sum of the mass of the bonding material and the mass of the metal oxide is in the range of 0.8; the metal oxide comprises the following materials in parts by mass: 35 parts by mass of CoO, 12 parts by mass of NiO, 28 parts by mass of MnO, 1.5 parts by mass of Y2O3, 1 part by mass of Al2O3, 1 part by mass of ZrO2, and 1.5 parts by mass of TiO2;

[0106] Step (2): The mixed slurry of the prepared adhesive material and metal oxide is coated between the copper foil and the aluminum foil to obtain an intermediate layer 2, forming a current collector 10, wherein the thickness of the intermediate layer 2 is 5 μm.

[0107] Step (3): coating the positive and negative electrode slurries on the current collector 10 to form the electrode sheet 20.

[0108] Step (4): The electrode plates are prepared into battery cells 300 through processes such as baking, rolling, slitting, and assembly.

[0109] Example 3

[0110] The method for preparing the battery cell 300 of Example 3 includes the following steps:

[0111] Step (1): Prepare a positive electrode slurry, the positive electrode material includes the following materials in parts by mass: 90 parts by mass of a positive electrode active material, 4.2 parts by mass of a conductive agent, 3.4 parts by mass of a binder and 2.4 parts by mass of a metal oxide, wherein the metal oxide includes the following materials in parts by mass: 1.05 parts by mass of CoO, 0.36 parts by mass of NiO, 0.84 parts by mass of MnO, 0.045 parts by mass of Y2O3, 0.03 parts by mass of Al2O3, 0.03 parts by mass of ZrO2, and 0.045 parts by mass of TiO2.

[0112] Step (2): The prepared positive electrode slurry is coated on the composite current collector 10 formed by copper foil and aluminum foil by coating to form an electrode plate 20.

[0113] Step (3): The electrode plates are prepared into battery cells 300 through processes such as baking, rolling, slitting, and assembly.

[0114] Comparative Example 1

[0115] The preparation method of the battery cell 300 of Comparative Example 1 includes the following steps:

[0116] Step (1): coating the positive and negative electrode slurries on the copper-aluminum composite current collector 10 to form the electrode plate 20.

[0117] Step (2): The electrode plate 20 is prepared into a battery cell 300 through processes such as baking, rolling, slitting, and assembly.

[0118] Comparative Example 2

[0119] The preparation method of the battery cell 300 of Comparative Example 2 includes the following steps:

[0120] Step (1): preparing bonding material slurry.

[0121] Step (2): The prepared adhesive material slurry is coated between the copper foil and the aluminum foil to obtain an intermediate layer 2, thereby forming a current collector 10, wherein the thickness of the intermediate layer 2 is 3 μm.

[0122] Step (3): coating the positive and negative electrode slurries on the current collector 10 to form the electrode sheet 20.

[0123] Step (4): The electrode plate 20 is prepared into a battery cell 300 through processes such as baking, rolling, slitting, and assembly.

[0124] Performance testing

[0125] The rolled battery pole pieces 20 and battery packages 100 prepared in the above-mentioned embodiments and comparative examples were subjected to pole piece-level membrane resistance and battery package 100-level operating cycle tests.

[0126] 1. Pole sheet resistance test method: Take the positive / negative electrode sheet after rolling, cut the battery electrode sheet 20 into 5cm×10cm strips, place it between the two electrodes of the electrode sheet resistance meter, turn on the equipment, set the test pressure, holding time, etc., and the equipment automatically reads the resistivity data of the battery electrode sheet. The results are shown in Table 1 below.

[0127] Table 1 Resistivity of battery electrodes corresponding to the embodiment and comparative example

[0128] Pole cathode materials Anode materials Resistivity / Ω·m Example 1 NCM111 graphite 0.1247 Example 2 NCM111 graphite 0.1276 Example 3 NCM111 graphite 0.1583 Comparative Example 1 NCM111 graphite 0.1230 Comparative Example 2 NCM111 graphite 0.1240

[0129] It should be noted that NCM111 is nickel cobalt manganese oxide (NiCoMnO2), a composite material made of a mixture of metal oxides such as nickel, cobalt, and manganese.

[0130] It can be seen from Table 1 that the resistivity of Example 1, Example 2, Example 3, and Comparative Example 1 and Comparative Example 2 are similar, ranging from 0.1230 / Ω·m to 0.1276 / Ω·m, indicating that the addition of the intermediate layer 2 between the first metal layer 1 and the second metal layer 3 of the current collector 10 in this application does not affect the conductive performance of the battery electrode 20.

[0131] 2. Battery pack 100 working condition cycle test method:

[0132] Capacity test:

[0133] (1) Adjust the ambient temperature to 25°C ± 2°C and leave for 6 hours;

[0134] (2) 1C discharge to the discharge cut-off voltage of 2.8V, and then stand for 30 minutes;

[0135] (3) 1C constant current and constant voltage charging to 4.2V, cut-off current 0.05C, and stand for 30 minutes;

[0136] (4) 1C discharge to the discharge cut-off voltage of 2.8V, and then stand for 30 minutes;

[0137] (5) Repeat steps (3) to (4) three times, with the third discharge capacity serving as the Q and 1C for subsequent charge and discharge capacities;

[0138] DC resistance test:

[0139] (1) Charge at 1C to 80% of the battery's state of charge and leave for 1 hour;

[0140] (2) 200A discharge for 10s, sampling frequency 0.1s, and shelving for 30s;

[0141] (3) 200A charging for 10s, sampling frequency 0.1s, and rest for 1h;

[0142] (4) Repeat steps (1) to (3) twice, testing the state of charge of 50% of the batteries and the state of charge of 30% of the batteries respectively.

[0143] Working cycle test:

[0144] (1) Adjust the ambient temperature to the test temperature and leave it for 6 hours;

[0145] (2) 1C discharge to a cut-off voltage of 2.8V, and then stand for 30 minutes;

[0146] (3) 1C charging to 55% battery state of charge;

[0147] (4) Perform 8 cycles of the World Light Duty Car Test (WLTC) cycle;

[0148] (5) Set aside for 2 hours;

[0149] (6) Repeat steps (3) to (5) twice;

[0150] (7) 1C discharge to a cut-off voltage of 2.8V, and then stand for 30 minutes;

[0151] (8) 1C charge to 75% battery state of charge;

[0152] (9) Carry out one test cycle simulating urban driving conditions (city);

[0153] (10) Repeat steps (3) to (9) 60 times;

[0154] (11) Generate and submit a detailed test report using the above-mentioned capacity test and DC resistance test results;

[0155] (12) Adjust the temperature of the environmental chamber to -10℃±2℃ and leave it for 12 hours;

[0156] (13) Adjust the temperature of the environmental chamber to 35℃±2℃ and leave it for 12 hours;

[0157] (14) Repeat steps (3) to (13) 11 times; the results are shown in Table 2 below.

[0158] Table 2 SOH extremes of each cell in the battery pack 100 after 300 cycles in the examples and comparative examples

[0159] Equivalent mileage SOH difference between cells Example 1 72727km 1.0％ Example 2 72727km 1.1％ Example 3 72727km 2.4％ Comparative Example 1 72727km 4.1％ Comparative Example 2 72727km 4.2％

[0160] It should be noted that the SOH range refers to the difference in the health status of different battery cells 300 in the battery pack 100. The SOH range is a parameter that describes the performance level or health status of the battery, measuring the accumulated loss and aging of the battery during long-term use. The equivalent mileage refers to the equivalent mileage obtained by testing the vehicle or powertrain under the above-mentioned test conditions by simulating various conditions in actual road driving (such as acceleration, deceleration, constant speed, idling, etc.).

[0161] It can be seen from Table 2 that under the same equivalent mileage, the SOH range of Examples 1 to 3 is smaller than the SOH range of Comparative Examples 1 and 2, indicating that when the material in the intermediate layer 2 of the current collector 10 of the present application includes a bonding material and a negative temperature coefficient thermistor material, the accumulated loss and aging of the battery package 100 during long-term use can be reduced, and the consistency of the life of the battery cell 300 in the battery package 100 can be improved. This is mainly because the temperature at different positions on the current collector 10 on the battery electrode 20 in the battery cell 300 is consistent.

[0162] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A current collector, characterized in that: include: A first metal layer, an intermediate layer, and a second metal layer are stacked in sequence; The materials of the intermediate layer include: bonding material and negative temperature coefficient thermistor material.

2. The current collector according to claim 1, characterized in that The negative temperature coefficient thermistor material includes: metal oxide.

3. The current collector according to claim 2, characterized in that The metal oxide includes at least one of cobalt oxide, nickel oxide, manganese oxide, yttrium oxide, aluminum oxide, zirconium oxide and titanium oxide.

4. The current collector according to claim 3, characterized in that The ratio of the sum of the mass of the cobalt oxide, the mass of the nickel oxide and the mass of the manganese oxide to the total mass of the metal oxide is in the range of 0.66 to 0.

95.

5. The current collector according to claim 3, characterized in that The metal oxide includes the following materials in parts by mass: 31 to 40 parts of cobalt oxide, 10 to 15 parts of nickel oxide, 25 to 40 parts of manganese oxide, 1 to 2 parts of yttrium oxide, 1 to 5 parts of aluminum oxide, 1 to 2 parts of zirconium oxide and 1 to 2 parts of titanium oxide.

6. The current collector according to claim 1, characterized in that The ratio of the mass of the negative temperature coefficient thermistor material to the total mass of the intermediate layer material is in the range of 0.7 to 0.

9.

7. The current collector according to claim 1, characterized in that The bonding material includes at least one of an ethoxy polymer, a vinylidene fluoride polymer, a silane polymer, an ether polymer and an ester polymer.

8. The current collector according to any one of claims 1 to 7, characterized in that The size of the intermediate layer in the first direction ranges from 1 μm to 5 μm; the first direction is the direction in which the first metal layer, the intermediate layer and the second metal layer are stacked in sequence.

9. A battery pole piece, characterized in that: include: The current collector according to any one of claims 1 to 8; The electrode active material is located on at least one side of the current collector.

10. A battery pole piece, characterized in that: include: current collector; a material layer, disposed on at least one side of the current collector; The materials of the material layer include: electrode active material, bonding material and negative temperature coefficient thermistor material.

11. The battery electrode according to claim 10, characterized in that: The material layer comprises the following materials in parts by mass: 85 to 96 parts of electrode active material, 1 to 6 parts of negative temperature coefficient thermistor material, and 1 to 4 parts of bonding material.

12. The battery electrode according to claim 10, characterized in that: The material of the material layer also includes: a conductive agent.

13. The battery electrode according to claim 12, characterized in that: The ratio of the mass of the electrode active material to the mass of the conductive agent is in the range of 17 to 48.

14. A battery cell, characterized in that: include: A battery cell shell and a battery pole piece according to any one of claims 9 to 13; The battery pole piece is arranged in the battery cell shell.

15. A battery pack, characterized in that: include: A plurality of battery cells and a battery package shell; the plurality of battery cells are arranged in the battery package shell; at least one of the plurality of battery cells is the battery cell according to claim 14.

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