Battery and electric device

Abstract

The invention belongs to the field of batteries, and discloses a battery and an electric device. The battery comprises a plurality of positive plates, a plurality of negative plates and a plurality of diaphragms, the positive plates and the negative plates are alternately stacked, and the diaphragms are arranged between the adjacent positive plates and negative plates. Wherein the positive plate comprises a positive plate C2 and a positive plate C1; the positive plate C2 comprises a metal foil positive current collector and a polyanion positive material layer arranged on at least one side of the metal foil positive current collector; the positive plate C1 comprises a positive current collector and a layered oxide positive material layer arranged on at least one side of the positive current collector, and the positive plate located on the outermost layer is a positive plate C2 in the stacking direction of the positive plate and the negative plate. The battery provided by the invention has high specific energy and high safety performance.

Description

Technical Field

[0001] This application belongs to the field of batteries, specifically relating to batteries and electrical devices. Background Technology

[0002] With the development of electric vehicles, low-altitude electric aircraft, electric motorcycles, robots, and mobile intelligent devices, the requirements for battery range and safety performance are becoming increasingly stringent. Range is positively correlated with battery energy density, but for lithium-ion rechargeable batteries, higher energy density generally leads to lower safety. Therefore, developing a battery that combines high energy density and high safety is currently one of the challenges.

[0003] Application content This application aims to at least partially address one of the technical problems in the related art. To this end, this application proposes a battery and an electrical device. The battery possesses both high energy density and high safety characteristics.

[0004] In a first aspect, this application provides a battery comprising a plurality of positive electrode plates, a plurality of negative electrode plates, and a plurality of separators, wherein the positive electrode plates and the negative electrode plates are alternately stacked, and the separators are disposed between adjacent positive electrode plates and negative electrode plates. The positive electrode includes positive electrode C2 and positive electrode C1; The positive electrode C2 includes a metal foil positive electrode current collector and a polyanion positive electrode material layer disposed on at least one side of the metal foil positive electrode current collector; The positive electrode C1 includes a positive current collector and a layered oxide positive electrode material layer disposed on at least one side of the positive current collector; In the stacking direction of the positive electrode and the negative electrode, the outermost positive electrode is the positive electrode C2.

[0005] In the battery of this application, in the stacking direction of the positive and negative electrodes, the middle positive electrode (C1) uses a layered oxide positive electrode material with high specific capacity, while the outermost positive electrode (C2) uses a polyanion positive electrode material with high thermal stability. Thus, through the combination of these two types of positive electrode materials and structural design, high specific energy and high safety performance are achieved. Specifically, when the battery is punctured by external force, the positive electrode C2, which uses polyanion positive electrode material, short-circuits with the adjacent negative electrode, generating less heat and making it less likely for thermal runaway to spread to the internal electrode sheets, thereby effectively reducing the risk of battery thermal runaway. Meanwhile, the middle positive electrode C1 can effectively exert its high specific energy function, thus ensuring the battery's high specific energy. Therefore, this battery can achieve both high specific energy and high safety performance.

[0006] In addition, the battery according to the above embodiments of this application may also have the following additional technical features: In some embodiments, the number of positive electrode plates C2 is less than the number of positive electrode plates C1.

[0007] In some embodiments, the positive electrode C1 includes a positive electrode C11 and a positive electrode C12; The positive electrode C11 includes the metal foil positive electrode current collector and the layered oxide positive electrode material layer disposed on at least one side of the metal foil positive electrode current collector; The positive electrode C12 includes a composite positive electrode current collector and a layered oxide positive electrode material layer disposed on at least one side of the composite positive electrode current collector. The composite positive electrode current collector includes a positive electrode polymer layer and positive electrode conductor layers disposed on opposite sides of the positive electrode polymer layer.

[0008] In some embodiments, at least one positive electrode C11 and / or at least one positive electrode C2 are spaced apart between two adjacent positive electrode plates C12.

[0009] In some embodiments, the positive electrode C11 satisfies at least one of the following conditions: The bifacial loading of the positive electrode C11 is 20~60 mg / cm³. 2 ; The compaction density of the positive electrode C11 is 2.5~4.5 g / cm³. 3 ; The height of the tab of the metal foil positive current collector in the positive electrode plate C11 is 7~15mm; The thickness of the metal foil positive electrode current collector in the positive electrode C11 is 5~15μm. This helps to improve the energy density and structural stability of the battery.

[0010] In some embodiments, the positive electrode C12 satisfies at least one of the following conditions: The bifacial loading of the positive electrode C12 is 20~60 mg / cm³. 2 ; The compacted density of the C12 positive electrode is 2.5~4.5 g / cm³. 3 ; The tab height of the composite positive current collector in the positive electrode C12 is 4~10mm; The thickness of the composite positive current collector in the positive electrode C12 is 4~15μm. This helps to improve the energy density and structural stability of the battery.

[0011] In some embodiments, the positive electrode C2 satisfies at least one of the following conditions: The bifacial loading of the positive electrode C2 is 25~65 mg / cm³. 2 ; The compaction density of the positive electrode C2 is 2.0~3.2 g / cm³. 3 ; The height of the tab of the metal foil positive current collector in the positive electrode plate C2 is 7~15mm; The thickness of the metal foil positive electrode current collector in the positive electrode C2 is 4~15μm. This helps to improve the energy density and structural stability of the battery.

[0012] In some embodiments, at least one of the following conditions is met: The polyanionic cathode material includes at least one of lithium manganese phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, and lithium nickel phosphate. The layered oxide cathode material includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-rich manganese-based materials. The metal foil positive current collector includes aluminum foil; The positive electrode conductor layer is made of aluminum; The positive electrode polymer layer is made of at least one of polyethylene terephthalate and polyimide. This contributes to improving the battery's energy density, structural stability, and safety performance.

[0013] In some embodiments, the negative electrode includes negative electrode A11 and negative electrode A12. The negative electrode A11 includes a metal foil negative electrode current collector and a negative electrode material layer disposed on at least one side of the metal foil negative electrode current collector; The negative electrode A12 includes a composite negative electrode current collector and a negative electrode material layer disposed on at least one side of the composite negative electrode current collector. The composite negative electrode current collector includes a negative electrode polymer layer and negative electrode conductor layers disposed on opposite sides of the negative electrode polymer layer. This helps to improve the safety performance of the battery.

[0014] In some embodiments, at least one of the following conditions is met: In the stacking direction, the outermost negative electrode is the negative electrode A11; There is at least one negative electrode A11 between two adjacent negative electrode plates A12. This helps to improve the safety performance of the battery, etc.

[0015] In some embodiments, the negative electrode A11 satisfies at least one of the following conditions: The bifacial loading of the negative electrode A11 is 10~30 mg / cm³. 2 ; The compaction density of the negative electrode A11 is 1.0~1.8 g / cm³. 3 ; The height of the tab of the metal foil negative electrode current collector in the negative electrode sheet A11 is 7~15mm; The thickness of the metal foil negative electrode current collector in the negative electrode sheet A11 is 3~10μm. This helps to improve the energy density and structural stability of the battery.

[0016] In some embodiments, the negative electrode A12 satisfies at least one of the following conditions: The bifacial loading of the negative electrode A12 is 10~30 mg / cm³. 2 ; The compaction density of the negative electrode A12 is 1.0~1.8 g / cm³. 3 ; The height of the tab of the composite negative electrode current collector in the negative electrode sheet A12 is 4~10mm; The thickness of the composite negative electrode current collector in the negative electrode sheet A12 is 3~10μm.

[0017] In some embodiments, at least one of the following conditions is met: The negative electrode current collector of the metal foil includes copper foil; The negative electrode conductor layer is made of aluminum; The material of the negative electrode polymer layer includes at least one of polyethylene terephthalate and polyimide.

[0018] In some embodiments, the battery includes: a first solder joint and a second solder joint for welding tabs on a plurality of positive electrode plates together, the second solder joint being located on the side of the first solder joint away from the positive electrode material layer.

[0019] A second aspect of this application provides an electrical device comprising the aforementioned battery. Therefore, this electrical device exhibits excellent electrochemical performance and a long service life. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the battery structure in one embodiment of this application. Detailed Implementation

[0021] Embodiments of this application are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting it.

[0022] This application is based on the inventor's following discoveries and understandings: In related technologies, the energy density of batteries can be effectively improved by using high-nickel ternary cathode materials (capacity can reach over 200 mAh / g) and lithium-rich manganese-based cathode materials (capacity can reach around 300 mAh / g). However, high-energy-density cathode materials have poor intrinsic thermal stability. At temperatures above 150℃, the crystal structure of these cathode materials is prone to transformation, which can lead to thermal runaway problems in the battery. For batteries using polyanionic cathode materials (such as lithium iron phosphate and lithium manganese iron phosphate), although polyanionic cathode materials have good thermal stability, their low specific energy (capacity of 140 mAh / g) reduces the battery's energy density.

[0023] Based on the above understanding, the inventors considered combining high-energy-density cathode materials and polyanion cathode materials to design a battery that has both high energy-density and high safety characteristics.

[0024] In view of this, a first aspect of this application provides a battery comprising a plurality of positive electrode plates, a plurality of negative electrode plates, and a plurality of separators, wherein the positive electrode plates and the negative electrode plates are alternately stacked, and the separators are disposed between adjacent positive electrode plates and negative electrode plates. Specifically, the positive electrode plates include positive electrode plate C2 and positive electrode plate C1. Positive electrode plate C2 comprises a metal foil positive electrode current collector and a polyanion positive electrode material layer disposed on at least one side of the metal foil positive electrode current collector; positive electrode plate C1 comprises a positive electrode current collector and a layered oxide positive electrode material layer disposed on at least one side of the positive electrode current collector. In the stacking direction of the positive and negative electrode plates, the outermost positive electrode plate is positive electrode plate C2.

[0025] In the battery of this application, in the stacking direction of the positive and negative electrodes, the middle positive electrode (C1) uses a layered oxide positive electrode material with high specific capacity, while the outermost positive electrode (C2) uses a polyanion positive electrode material with high thermal stability. Thus, through the combination of these two types of positive electrode materials and structural design, high specific energy and high safety performance are achieved. Specifically, when the battery is punctured by external force, the positive electrode C2, which uses polyanion positive electrode material, short-circuits with the adjacent negative electrode, generating less heat and making it less likely for thermal runaway to spread to the internal electrode sheets, thereby effectively reducing the risk of battery thermal runaway. Meanwhile, the middle positive electrode C1 can effectively exert its high specific energy function, thus ensuring the battery's high specific energy. Therefore, this battery can achieve both high specific energy and high safety performance.

[0026] For example, when the positive and negative electrode plates are alternately stacked in a bottom-to-top direction, the statement in this document that "the outermost positive electrode plate is positive electrode plate C2 in the stacking direction of the positive and negative electrode plates" means that the bottommost and topmost positive electrode plates are positive electrode plates C2. Similar meanings apply to different stacking directions, and will not be elaborated further here.

[0027] In some embodiments, the number of positive electrode plates C2 is less than the number of positive electrode plates C1. Positive electrode plate C1 is a high-energy-density layered oxide positive electrode plate, which determines the battery's energy density. Positive electrode plate C2 is a thermally stable polyanion positive electrode plate, which determines the battery's safety performance. This arrangement allows for a higher proportion of high-energy-density positive electrode material in the battery, resulting in higher energy density, while also ensuring safety performance.

[0028] In most related technical solutions, metal foil current collectors are used for the positive and negative electrodes of the battery. When an internal short circuit occurs (such as when the positive and negative electrodes come into contact or the separator is damaged), the short circuit generates a large amount of heat. However, because of their high melting point, metal foil current collectors cannot melt and break the circuit in time, so the short circuit persists. As the short circuit time increases, heat continues to accumulate, which can eventually lead to battery thermal runaway (fire or explosion). Some batteries use composite current collectors (with relatively low melting points) for the positive and negative electrodes. While this improves safety, it increases the difficulty of manufacturing and reduces the conductivity and thermal conductivity of the current collectors on the corresponding electrodes. This increases the battery's internal resistance and heat generation, preventing internal heat from being dissipated from the tabs in time, causing the internal temperature of the battery to rise and accelerating the degradation of the battery's lifespan.

[0029] To address the aforementioned issues, the battery of this application combines a metal foil current collector and a composite current collector. Therefore, in some embodiments, the positive electrode C1 comprises a positive electrode C11 and a positive electrode C12. The positive electrode C11 comprises the metal foil positive current collector and a layered oxide positive electrode material layer disposed on at least one side of the metal foil positive current collector; the positive electrode C12 comprises a composite positive current collector and a layered oxide positive electrode material layer disposed on at least one side of the composite positive current collector. This approach balances battery conductivity, low internal resistance, and safety performance.

[0030] Specifically, the metal foil positive electrode current collector includes aluminum foil. It exhibits strong electrochemical stability, does not undergo side reactions with the positive electrode material or electrolyte, and can maintain the stability of the positive electrode current collector over a long period.

[0031] The composite positive electrode current collector includes a positive electrode polymer layer and positive electrode conductor layers disposed on opposite sides of the positive electrode polymer layer. The positive electrode conductor layer is made of aluminum, and the positive electrode polymer layer is made of at least one of PET (polyethylene terephthalate) and PI (polyimide).

[0032] High-energy-density cathode materials utilize composite foil, which can promptly cut off the electron path at the corresponding location in the event of an internal short circuit, shortening the short circuit time and thus reducing heat generation. This lowers the risk of thermal runaway in cathode materials with poor thermal stability. Therefore, while ensuring the battery's thermal and electrical conductivity, it further improves the battery's safety performance. Furthermore, composite current collectors are easier to process and are lighter than metal current collectors, allowing for a certain degree of improvement in gravimetric energy density.

[0033] In some embodiments, at least one positive electrode C11 and / or at least one positive electrode C2 (polyanion positive electrode) is spaced between two adjacent positive electrode plates C12. The spacer of positive electrode plate C11 between the two positive electrode plates C12 ensures the battery's electrical and thermal conductivity. The spacer of positive electrode plate C2 between the two positive electrode plates C12 helps regulate heat generation and isolate heat, reducing the risk of thermal runaway of the entire battery. Furthermore, the presence of metal current collectors on both sides of the composite current collector positive electrode facilitates the welding and connection of the composite current collector.

[0034] For example, refer to Figure 1 As can be seen, the positive and negative electrode plates in the battery are alternately stacked, with the separator positioned between adjacent positive and negative electrode plates. Furthermore, it can be observed that the outermost positive electrode plate is positive electrode plate C2. The middle positive electrode plates can be arranged according to actual needs and the description above.

[0035] In some embodiments, the bifacial loading of the positive electrode C11 is 20 mg / cm². 2 ~60mg / cm 2 Specifically, it can be 20 mg / cm³ 2 25 mg / cm 2 30 mg / cm 2 35 mg / cm 2 40 mg / cm 2 45 mg / cm 2 50 mg / cm 2 55 mg / cm 2 60 mg / cm 2 Within the above-mentioned loading range, a greater amount of layered oxide cathode material can be loaded, thereby increasing the energy density of the battery.

[0036] In some embodiments, the bifacial loading of C12 on the positive electrode is 20 mg / cm³. 2 ~60mg / cm 2 Specifically, it can be 20 mg / cm³ 2 25 mg / cm 2 30 mg / cm 2 35 mg / cm 2 40 mg / cm 2 45 mg / cm 2 50 mg / cm 2 55 mg / cm 2 60 mg / cm 2 Within the above-mentioned loading range, a greater amount of layered oxide cathode material can be loaded, thereby increasing the energy density of the battery.

[0037] In some embodiments, the bifacial loading of the positive electrode C2 is 25 mg / cm². 2 ~65mg / cm 2 Specifically, it can be 25mg / cm 2 30 mg / cm 2 35 mg / cm 2 40 mg / cm 2 45 mg / cm 2 50 mg / cm 2 55 mg / cm 2 60 mg / cm 2 65mg / cm 2 Within the above range, a greater amount of polyanion cathode material can be loaded, thus ensuring that the cathode C2 also has high capacity performance, thereby improving the energy density of the battery.

[0038] In some embodiments, the layered oxide cathode material on the cathode sheet C11 or C12 includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-rich manganese-based materials. These cathode materials exhibit excellent capacity performance, contributing to the production of high-energy-density batteries.

[0039] For example, lithium nickel cobalt manganese oxide includes NCM111, NCM532, NCM613, NCM712, NCM811, etc. Among them, NCM111 refers to a cathode material with a nickel, cobalt, and manganese molar ratio of 1:1:1 (i.e., Ni...). 1 / 3 Co 1 / 3 Mn 1 / 3 O2). NCM532 refers to a cathode material with a nickel, cobalt, and manganese molar ratio of 5:3:2 (i.e., Ni). 0.5 Co 0.3 Mn 0.2 O2). NCM613 refers to a cathode material with a molar ratio of nickel, cobalt, and manganese of 6:1:3 (i.e., Ni). 0.6 Co 0.1 Mn 0.3 O2).

[0040] In some embodiments, the polyanionic cathode material on the cathode sheet C2 includes at least one of lithium manganese phosphate, lithium iron manganese phosphate (LFMP), lithium vanadium phosphate, lithium cobalt phosphate, and lithium nickel phosphate. These cathode materials exhibit excellent thermal stability, which helps improve the safety performance of the battery.

[0041] In some embodiments, the layered oxide cathode material layer on cathode C11 or C12 or the polyanionic cathode material layer on cathode C2 may also include cathode conductive agent and cathode binder, and additives with specific functions and effects may also be added as needed, such as lithium supplement, film-forming additive, flame retardant, high temperature / low temperature stabilizer, etc.

[0042] In some embodiments of this application, the positive electrode adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a terpolymer of PVDF-tetrafluoroethylene-propylene, a terpolymer of PVDF-hexafluoropropylene-tetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorinated acrylate resin. This allows the positive electrode dressing layer to adhere well to the positive electrode current collector, resulting in strong adhesion and reducing the likelihood of problems such as positive electrode dressing detachment.

[0043] In some embodiments of this application, the positive electrode conductive agent may include at least one selected from Super P, superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes (CNTs), graphene, and carbon nanofibers. This effectively improves conductivity, reduces internal resistance, and enhances the electrochemical performance of lithium-ion batteries.

[0044] In some embodiments, the compaction density of the positive electrode C11 is 2.5 g / cm³. 3 ~4.5g / cm 3 Specifically, it can be 2.5g / cm³. 3 3 g / cm 3 3.5 g / cm 3 4 g / cm 3 4.5 g / cm 3 Or a range between the above two. The compaction density within the above range can basically ensure sufficient contact between the positive electrode material particles on the positive electrode sheet C11, thereby ensuring the electronic conductivity of the electrode, reducing the internal resistance of the electrode, promoting the electrochemical reaction, and improving the power performance of the battery.

[0045] In some embodiments, the compaction density of the positive electrode C12 is 2.5 g / cm³. 3 ~4.5g / cm 3 Specifically, it can be 2.5g / cm³. 3 3 g / cm 3 3.5 g / cm 3 4 g / cm 3 4.5 g / cm 3Or a range between the above two. The compaction density within the above range can basically ensure sufficient contact between the positive electrode material particles on the positive electrode sheet C12, thereby ensuring the electronic conductivity of the electrode, reducing the internal resistance of the electrode, promoting the electrochemical reaction, and improving the power performance of the battery.

[0046] In some embodiments, the compaction density of the positive electrode C2 is 2.0 g / cm³. 3 ~3.2g / cm 3 Specifically, it can be 2.0 g / cm³. 3 2.2 g / cm 3 2.4 g / cm 3 2.6 g / cm 3 2.8 g / cm 3 3.0 g / cm 3 3.2 g / cm 3 The compaction density within the above range can basically ensure sufficient contact between the positive electrode material particles on the positive electrode C2, thereby ensuring the electronic conductivity of the electrode, reducing the internal resistance of the electrode, promoting the electrochemical reaction, and improving the power performance of the battery.

[0047] In this article, the compaction density of the positive electrode sheet refers to the mass of the positive electrode material per unit volume. It can be calculated using the following formula: Compaction density of the positive electrode sheet = Mass of the positive electrode material / Volume of the positive electrode sheet. Specifically, it can be tested by punching 10cm pieces of the rolled positive electrode sheet. 2 For the circular discs, measure their weight and thickness; compaction density = (total weight of discs - weight of disc foil) g / (total thickness of discs - thickness of foil) cm / 10cm 2 .

[0048] In some embodiments, refer to Figure 1 The tab height H of the metal foil positive current collector in the positive electrode C11 is 7mm to 15mm. Specifically, it can be 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, or any range between two of them. The tab height of the positive electrode C11 can be designed according to the different sizes of the battery cells.

[0049] In some embodiments, the tab height of the composite positive current collector in the positive electrode C12 is 4 mm to 10 mm. Specifically, it can be 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or any combination thereof. A tab height within the above range helps to improve the current collection effect among multiple positive current collectors, and also helps to improve the transition strength of the tabs on multiple positive current collectors.

[0050] In some embodiments, the tab height of the metal foil positive current collector in the positive electrode C2 is 7-15 mm. Specifically, it can be 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, or any range between two of them. The tab height can be flexibly designed according to the size of the battery cell to ensure smooth connection between all tabs.

[0051] In some embodiments, the thickness of the metal foil positive current collector in the positive electrode C11 is 5~15 μm. Specifically, it can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc. The thickness of the metal foil positive current collector in the positive electrode C11 within the above range can basically ensure the mechanical stability of the positive electrode C11. This ensures that the positive current collector stably supports the positive electrode material without affecting the gravimetric energy density of the positive electrode due to excessive thickness of the positive current collector.

[0052] In some embodiments, the thickness of the composite positive current collector in the positive electrode C12 is 4~15 μm. Specifically, it can be 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc. This essentially ensures the mechanical stability of the positive electrode C12.

[0053] In some embodiments, the thickness of the metal foil positive current collector in the positive electrode C2 is 4~15 μm. Specifically, it can be 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc. This essentially ensures the mechanical stability of the positive electrode C2.

[0054] In some embodiments, the negative electrode in the battery of this application includes a negative electrode A11 and a negative electrode A12. Negative electrode A11 includes a metal foil negative electrode current collector and a negative electrode material layer disposed on at least one side of the metal foil negative electrode current collector; negative electrode A12 includes a composite negative electrode current collector and the negative electrode material layer disposed on at least one side of the composite negative electrode current collector. Thus, the negative electrode combines the metal foil current collector and the composite current collector, which can further ensure the battery's thermal and electrical conductivity while further improving the battery's safety performance.

[0055] In some embodiments, the metal foil negative electrode current collector includes copper foil. Copper has excellent conductivity, enabling efficient electron transfer to the negative electrode, reducing the internal resistance of the electrode, and improving the rate performance of the battery. Simultaneously, copper does not undergo side reactions with the negative electrode material.

[0056] In some embodiments, the composite negative electrode current collector includes a negative electrode polymer layer and negative electrode conductor layers disposed on opposite sides of the negative electrode polymer layer. The negative electrode conductor layer is made of aluminum. The negative electrode polymer layer is made of at least one of PET (polyethylene terephthalate) and PI (polyimide). The composite current collector described above has a relatively low melting point, which helps to improve battery safety performance.

[0057] In some embodiments of this application, the negative electrode material layer includes a negative electrode active material, such as artificial graphite, porous carbon, etc. These negative electrode active materials possess excellent capacity performance and low cost; different active materials can be selected according to actual needs.

[0058] In some embodiments of this application, the negative electrode material layer may further include a negative electrode conductive agent, a negative electrode binder, a thickener, etc. The negative electrode binder may include, but is not limited to, 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). The negative electrode conductive agent may include, but is not limited to, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The thickener includes sodium carboxymethyl cellulose (CMC), etc.

[0059] In some embodiments, refer to Figure 1 In the stacking direction, the outermost negative electrode is negative electrode A11, and there is at least one negative electrode A11 between two adjacent negative electrode sheets A12. The outermost negative electrode directly contacts the battery casing or the external environment. Using negative electrode A11 can better support the stacked structure of the battery (negative electrode A11 has excellent mechanical stability and can prevent deformation of the outer electrode sheets). At the same time, the high electrical and thermal conductivity of negative electrode A11 allows for smoother electron transport and heat dissipation in the outer layer, avoiding excessively high internal resistance and localized overheating, and ensuring the overall stability of the cell performance.

[0060] In some embodiments, the bifacial loading of the negative electrode Al1 is 10~30 mg / cm². 2 Specifically, it can be 10 mg / cm³. 2 15 mg / cm 2 20 mg / cm 2 25 mg / cm 2 30 mg / cm 2 And so on. A loading capacity within the above range can accommodate a larger amount of negative electrode material, matching the capacity of the positive electrode and ensuring the battery's energy density.

[0061] In some embodiments, the compaction density of the negative electrode A11 is 1.0~1.8 g / cm³.3 Specifically, it can be 1.0 g / cm³. 3 1.2 g / cm 3 1.4 g / cm 3 1.6 g / cm 3 1.8 g / cm 3 Or a range between the above two. The compaction density within the above range can basically ensure sufficient contact between the negative electrode material particles on the negative electrode sheet A11, thereby ensuring the electronic conductivity of the electrode, reducing the internal resistance of the electrode, promoting the electrochemical reaction, and improving the power performance of the battery.

[0062] In this article, the compaction density of the negative electrode sheet refers to the mass of the negative electrode material per unit volume. It can be calculated using the following formula: Compaction density of the negative electrode sheet = Mass of the negative electrode material / Volume of the negative electrode sheet. Specifically, it can be tested by punching 10cm pieces of the rolled negative electrode sheet. 2 For the circular discs, measure their weight and thickness; compaction density = (total weight of discs - weight of disc foil) g / (total thickness of discs - thickness of foil) cm / 10cm 2 .

[0063] In some embodiments, the tab height of the metal foil negative electrode current collector in the negative electrode sheet A11 is 7~15mm. Specifically, it can be 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, or any range between two of them. The tab height of the negative electrode sheet A11 can be designed according to the different sizes of the battery cells.

[0064] In some embodiments, the thickness of the metal foil negative electrode current collector in the negative electrode sheet A11 is 3~10 μm. Specifically, it can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc. The thickness of the metal foil positive electrode current collector in the negative electrode sheet A11 within the above range can basically ensure the mechanical stability of the negative electrode sheet A11, ensuring that the negative electrode current collector stably supports the negative electrode material, thereby improving the capacity performance of the battery.

[0065] In some embodiments, the bifacial loading of the negative electrode A12 is 10~30 mg / cm². 2 Specifically, it can be 10 mg / cm³. 2 15 mg / cm 2 20 mg / cm 2 25 mg / cm 2 30 mg / cm 2 And so on. A loading capacity within the above range can accommodate a larger amount of negative electrode material, matching the capacity of the positive electrode and ensuring the battery's energy density.

[0066] In some embodiments, the compaction density of the negative electrode A12 is 1.0~1.8 g / cm³. 3 Specifically, it can be 1.0 g / cm³. 3 1.2 g / cm 3 1.4 g / cm 3 1.6 g / cm 3 1.8 g / cm 3 Or a range between the above two. The compaction density within the above range can basically ensure sufficient contact between the negative electrode material particles on the negative electrode sheet A12, thereby ensuring the electronic conductivity of the electrode, reducing the internal resistance of the electrode, promoting the electrochemical reaction, and improving the power performance of the battery.

[0067] In some embodiments, the tab height of the composite negative current collector in the negative electrode sheet A12 is 4-10 mm. Specifically, it can be 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or any combination thereof. A tab height within the above range helps improve the current collection effect among multiple negative current collectors, and also helps improve the connection strength of the tabs on multiple negative current collectors. The tab height can be flexibly designed according to the size of the battery cell, ensuring smooth connection between all tabs.

[0068] In some embodiments, the thickness of the composite negative electrode current collector in the negative electrode sheet A12 is 3~10 μm. Specifically, it can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc. The thickness of the metal foil positive electrode current collector in the negative electrode sheet A12 within the above range can basically ensure the mechanical stability of the negative electrode sheet A12, ensuring that the negative electrode current collector stably supports the negative electrode material, thereby improving the capacity performance of the battery.

[0069] In some embodiments, the battery of this application includes a first solder joint and a second solder joint for welding the tabs on the plurality of positive electrode plates together, wherein the second solder joint is located on the side of the first solder joint away from the positive electrode material layer. Specifically, the first solder joint close to the positive electrode material layer is to ensure that all the tabs are welded together, ensuring electron current collection for all positive electrode plates (C11, C12, and C2); the second solder joint away from the positive electrode material layer is to weld the current collector tabs of positive electrode plates C11 and C2 together again, which can enhance the current conduction effect and strength of the tabs after welding.

[0070] For example, the welding process for the current collector in the positive or negative electrode is as follows: The first welding is performed close to the positive electrode material layer (e.g., welding according to the height of the positive electrode C12 tab), where all the current collectors of the positive electrode can be bundled together; the second welding is performed on the side away from the positive electrode material layer, i.e., the welding height is higher than the height of the positive electrode C12 tab, again bundling the metal foil current collectors (positive electrode C11 and positive electrode C2) into a whole for connecting to the tab containing the tab adhesive block. Welding options include ultrasonic welding, laser welding, and resistance welding, with ultrasonic welding being preferred.

[0071] According to the embodiments of this application, it can be understood that there is no particular limitation on the specific type of battery, which can be a primary battery or a secondary battery; the shape of the battery can be a cylindrical battery, a square battery or other arbitrary shape batteries, and according to the outer packaging, the battery can be a hard-shell battery, a soft-pack battery, etc.

[0072] Typically, a battery includes the aforementioned positive electrode, negative electrode, electrolyte, and separator. The positive electrode, negative electrode, and separator can be manufactured into a cell using winding or stacking processes. The cell and electrolyte can be housed in an outer packaging. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0073] In some embodiments, the battery in this application can be an all-solid-state battery, including the above-mentioned positive electrode, negative electrode and separator, etc. During the charging and discharging process of the battery, active ions are inserted and extracted back and forth between the positive electrode and the negative electrode. The separator is disposed between the positive electrode and the negative electrode, mainly to prevent short circuit between the positive electrode and the negative electrode, while allowing active ions to pass through.

[0074] In some embodiments, the separator may be a separator known in the art that can be used in lithium-ion batteries and is stable to the electrolyte used, such as a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene composite separator, etc.

[0075] According to embodiments of this application, the electrolyte may include lithium salt and solvent. Furthermore, additives with specific functions, such as film-forming additives, lithium replenishing agents, flame retardants, and thermal stability additives, may be added to the electrolyte as needed. As an example, the electrolyte may include lithium salt, solvent, and additives. In some embodiments of this application, the lithium salt may include LIPF6. Lithium salt can provide lithium ions to the battery, support the stability of the electrolyte and electrochemical reactions, help form a protective SEI film, improve conductivity, and enhance the safety of lithium-ion batteries.

[0076] According to embodiments of this application, the solvent may include carbonates, fluorocarbonates, etc. This allows for the sufficient dissolution of lithium salts, provides an ion transport medium, and also helps improve the electrochemical and safety performance of lithium-rich manganese-based batteries.

[0077] According to the embodiments of this application, the battery can be a single cell, a battery module, or a battery pack. The specific structure of the battery module or battery pack is not particularly limited and can be carried out with reference to conventional techniques in the art.

[0078] In a second aspect of this application, an electrical device is provided, comprising the aforementioned battery. Therefore, this electrical device exhibits excellent electrochemical performance and a long service life.

[0079] In some embodiments, the specific type of electrical device is not particularly limited and can be any device that uses a battery as a power source or energy storage unit. Examples of electrical devices include, but are not limited to, electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), mobile terminals (e.g., mobile phones, laptops, game consoles, wearable devices, etc.), drones, aerospace equipment, satellites, ships, energy storage systems, and so on.

[0080] It is understood that, in addition to the battery mentioned above, the electrical device also includes other necessary structures and components, all of which can be made with reference to conventional technologies. For example, an electric vehicle may include a body, chassis, tires, navigation system, radar system, steering system, braking system, lubrication system, cooling system, driving system, etc., which will not be described in detail here.

[0081] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.

[0082] Example 1 Preparation of positive electrode: a. The positive electrode active material NCM613, conductive agent 1 (Super P), conductive agent 2 (CNTs), and binder (PVDF) are mixed in a weight ratio of 97:0.75:0.75:1.5, poured into N-methyl-2-pyrrolidone solvent, mixed and stirred evenly to obtain a positive electrode slurry Z1 with a solid content of 75wt%. b. Mix the positive electrode active material lithium vanadium phosphate, conductive agent 1 (Super P), conductive agent 2 (CNTs), and binder (PVDF) in a weight ratio of 96:1:1:2, pour the mixture into N-methyl-2-pyrrolidone, mix and stir evenly to obtain a positive electrode slurry Z2 with a solid content of 70%. c. Part of the positive electrode slurry Z1 was coated on both sides onto a 12μm thick aluminum foil current collector. After drying, the total coating loading was 30.9 mg / cm³. 2 The positive electrode plate C11 is obtained; d. The remaining positive electrode slurry Z1 was coated on both sides onto a 12μm thick composite aluminum foil current collector. After drying, the total coating loading was 30.9 mg / cm³. 2 The positive electrode plate C12 is obtained; e. The positive electrode slurry Z2 was coated on both sides onto a 12μm thick aluminum foil current collector. After drying, the total coating loading was 43.1 mg / cm³. 2 The positive electrode C2 is obtained; f. Roll the positive electrode plates C11 and C12 to a thickness of 100 μm; roll the positive electrode plate C2 to a thickness of 178 μm.

[0083] Preparation of negative electrode: a. The negative electrode active material artificial graphite, conductive agent (Super P), thickener CMC and binder SBR are mixed in a weight ratio of 94.5:1.5:1.5:2.5, water is added and stirred until uniform, to obtain a negative electrode slurry F with a solid content of 50wt%; b. Part of the negative electrode slurry F was coated onto a 6μm copper foil current collector. After drying, the total coating loading was 19.2 mg / cm³. 2 The negative electrode A11 is obtained; c. The remaining negative electrode slurry F was coated onto a 6μm composite copper foil current collector. After drying, the total coating loading was 19.2 mg / cm³. 2 The negative electrode A12 is obtained; d. Roll the negative electrode sheets A11 and A12 to a thickness of 121 μm.

[0084] The manufacturing process of lithium-ion batteries: a. Die-cut the positive and negative electrode sheets obtained by the above process so that the tab height of C11, C2 and A11 is 10mm and the tab height of C12 and A12 is 6mm. b. The core package is formed by stacking the PE separator with the core. The specific stacking sequence is: A11 / C2 / A12 / C12 / A11 / C11 / A12 / C12 / A11 / C11 / A12 / C12 / A11 / C2 / A12 / C12 / A11 / C11 / A12 / C12 / A11 / C11 / A12 / C12 / A11 / C12 / A12 / C12 / A11 / C11 / A12 / C12 / A11 / C2 / A11, where a separator is stacked between the positive and negative electrodes, which is omitted here.

[0085] c. The electrode tabs are ultrasonically welded in two stages. The first welding is 3mm away from the material area and the weld width is 3mm. The second welding is 0.5mm away from the edge of the first weld and the weld width is 4mm. d. After ultrasonically welding the tabs with adhesive tape, seal with aluminum-plastic film; e. Electrolyte preparation: Mix the lithium salt, solvent, and additives. Specifically, the concentration of lithium salt LiPF6 in the electrolyte is 1.3 mol / L; the solvent mass ratio is EC:EMC = 3:7; based on the total mass of the electrolyte, the additives are: vinylene carbonate (VC) 0.5 wt% VC; fluoroethylene carbonate (FEC) 1.0 wt% VC; 1,3-propanesulfonate lactone (1,3-PS) 0.8 wt% 1.5 wt% 1.5 wt% 1.0 ... f. Inject the above electrolyte into the packaged battery cell, let it stand, form, degas, age, and test its capacity, and then conduct relevant performance tests with a voltage range of 2.75~4.35V.

[0086] Examples 2-3 Same as Example 1, the main differences are shown in Tables 1 and 2.

[0087] Comparative Examples 1-3 Same as Example 1, the main differences are shown in Tables 1 and 2.

[0088] Test methods The batteries were weighed, tested for energy, and subjected to nail penetration tests at 25°C, as follows: Discharge energy test method: Charge at 0.5C constant current and constant voltage to the corresponding upper limit voltage, and cut off the current to 0.05C; discharge at 0.5C constant current to the lower limit voltage, and the charging and discharging equipment records the corresponding discharge energy; Needle penetration test method: Charge the battery cell at 0.5C constant current and constant voltage to the corresponding upper limit voltage, cut off the current to 0.05, let it stand for 1 hour, attach the temperature sensing wire near the center of the battery cell, and use a 5mm diameter high temperature resistant steel needle (the cone angle of the needle tip is 45°) to penetrate from the direction perpendicular to the battery cell plate at a speed of 25mm / s. The penetration position should be close to the geometric center of the pierced surface. The steel needle stays in the battery cell and is observed for 1 hour.

[0089] Test results The battery performance test results in the examples and comparative examples are shown in Table 3.

[0090]

[0091]

[0092] Conclusion: The battery performance data from Examples 1-3 and Comparative Examples 1-3 show that, when using the same positive electrode active material, the energy density of the battery in this application is higher than that of the battery in the comparative examples, and both passed the nail penetration test with a lower temperature rise than the comparative examples. This indicates that the battery in this application can achieve both high specific energy and high safety.

[0093] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0094] Furthermore, 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0095] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0096] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0097] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0098] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A battery, characterized in that, It includes multiple positive electrode plates, multiple negative electrode plates, and multiple separators, wherein the positive electrode plates and the negative electrode plates are alternately stacked, and the separators are disposed between adjacent positive electrode plates and negative electrode plates; The positive electrode includes positive electrode C2 and positive electrode C1; The positive electrode C2 includes a metal foil positive electrode current collector and a polyanion positive electrode material layer disposed on at least one side of the metal foil positive electrode current collector; The positive electrode C1 includes a positive current collector and a layered oxide positive electrode material layer disposed on at least one side of the positive current collector; In the stacking direction of the positive electrode and the negative electrode, the outermost positive electrode is the positive electrode C2.

2. The battery according to claim 1, characterized in that, The number of positive electrode plates C2 is less than the number of positive electrode plates C1.

3. The battery according to claim 1, characterized in that, The positive electrode C1 includes positive electrode C11 and positive electrode C12; The positive electrode C11 includes the metal foil positive electrode current collector and the layered oxide positive electrode material layer disposed on at least one side of the metal foil positive electrode current collector; The positive electrode C12 includes a composite positive electrode current collector and a layered oxide positive electrode material layer disposed on at least one side of the composite positive electrode current collector. The composite positive electrode current collector includes a positive electrode polymer layer and positive electrode conductor layers disposed on opposite sides of the positive electrode polymer layer.

4. The battery according to claim 3, characterized in that, There is a gap of at least one positive electrode C11 and / or at least one positive electrode C2 between two adjacent positive electrode plates C12.

5. The battery according to claim 3, characterized in that, The positive electrode C11 satisfies at least one of the following conditions: The bifacial loading of the positive electrode C11 is 20~60 mg / cm³. 2 ; The compaction density of the positive electrode C11 is 2.5~4.5 g / cm³. 3 ; The height of the tab of the metal foil positive current collector in the positive electrode plate C11 is 7~15mm; The thickness of the metal foil positive current collector in the positive electrode C11 is 5~15μm.

6. The battery according to claim 3, characterized in that, The positive electrode C12 satisfies at least one of the following conditions: The bifacial loading of the positive electrode C12 is 20~60 mg / cm³. 2 ; The compacted density of the C12 positive electrode is 2.5~4.5 g / cm³. 3 ; The tab height of the composite positive current collector in the positive electrode C12 is 4~10mm; The thickness of the composite positive current collector in the positive electrode C12 is 4~15μm.

7. The battery according to claim 1, characterized in that, The positive electrode C2 satisfies at least one of the following conditions: The bifacial loading of the positive electrode C2 is 25~65 mg / cm³. 2 ; The compaction density of the positive electrode C2 is 2.0~3.2 g / cm³. 3 ; The height of the tab of the metal foil positive current collector in the positive electrode plate C2 is 7~15mm; The thickness of the metal foil positive current collector in the positive electrode C2 is 4~15μm.

8. The battery according to claim 3, characterized in that, At least one of the following conditions must be met: The polyanionic cathode material includes at least one of lithium manganese phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, and lithium nickel phosphate. The layered oxide cathode material includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-rich manganese-based materials. The metal foil positive current collector includes aluminum foil; The positive electrode conductor layer is made of aluminum; The material of the positive electrode polymer layer includes at least one of polyethylene terephthalate and polyimide.

9. The battery according to claim 1, characterized in that, The negative electrode includes negative electrode A11 and negative electrode A12. The negative electrode A11 includes a metal foil negative electrode current collector and a negative electrode material layer disposed on at least one side of the metal foil negative electrode current collector; The negative electrode A12 includes a composite negative electrode current collector and a negative electrode material layer disposed on at least one side of the composite negative electrode current collector. The composite negative electrode current collector includes a negative electrode polymer layer and negative electrode conductor layers disposed on opposite sides of the negative electrode polymer layer.

10. The battery according to claim 9, characterized in that, At least one of the following conditions must be met: In the stacking direction, the outermost negative electrode is the negative electrode A11; There is at least one negative electrode A11 between two adjacent negative electrode plates A12.

11. The battery according to claim 9, characterized in that, The negative electrode A11 satisfies at least one of the following conditions: The bifacial loading of the negative electrode A11 is 10~30 mg / cm³. 2 ; The compaction density of the negative electrode A11 is 1.0~1.8 g / cm³. 3 ; The height of the tab of the metal foil negative electrode current collector in the negative electrode sheet A11 is 7~15mm; The thickness of the metal foil current collector in the negative electrode A11 is 3~10μm.

12. The battery according to claim 9, characterized in that, The negative electrode A12 satisfies at least one of the following conditions: The bifacial loading of the negative electrode A12 is 10~30 mg / cm³. 2 ; The compaction density of the negative electrode A12 is 1.0~1.8 g / cm³. 3 ; The height of the tab of the composite negative electrode current collector in the negative electrode sheet A12 is 4~10mm; The thickness of the composite negative electrode current collector in the negative electrode sheet A12 is 3~10μm.

13. The battery according to claim 9, characterized in that, At least one of the following conditions must be met: The negative electrode current collector of the metal foil includes copper foil; The material of the negative electrode conductor layer includes aluminum; The material of the negative electrode polymer layer includes at least one of polyethylene terephthalate and polyimide.

14. The battery according to claim 1, characterized in that, include: A first solder joint and a second solder joint are used to weld the tabs on the plurality of positive electrode plates together, wherein the second solder joint is located on the side of the first solder joint away from the positive electrode material layer.

15. An electrical device comprising the battery according to any one of claims 1 to 14.

Images