Battery and electric device

Abstract

This application relates to a battery and an electrical device. The battery includes a positive electrode, a negative electrode, a separator, and an electrolyte; the positive electrode active material layer includes aluminum; the separator includes an oxide solid electrolyte coating; the electrolyte includes a solvent, an additive, and a lithium salt; the solvent includes a first solvent and a second solvent; the additive includes a first additive and a second additive; the first solvent includes propylene carbonate and / or ethylene carbonate, and the second solvent includes ethyl 2,2-difluoroacetate and / or trifluoroethyl methyl carbonate; the first additive includes mannitol sulfate, and the second additive includes ethylene sulfate; 0.08≤(A+C+D)×10000 / X≤0.77; 0.05≤(C+D)×100 / (B+W)≤2.77; 3.23≤(C+H) / B≤63.97. The solution provided in this application results in a battery exhibiting excellent thermal shock safety and high and low temperature cycling performance.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more particularly to batteries and electrical devices. Background Technology

[0002] Lithium-ion batteries have become the core energy source for electric vehicles, energy storage systems, and consumer electronics due to their advantages such as high energy density and long cycle life.

[0003] However, lithium-ion batteries still face a series of challenges in practical applications: under extreme thermal abuse conditions (such as thermal shock), traditional liquid electrolytes are prone to decomposition and gas production, posing a risk of thermal runaway; at low temperatures (0°C), electrolyte viscosity increases and ionic conductivity decreases, leading to a sharp decline in battery cycle performance and rate performance; during long-term cycling at high temperatures (45°C), side reactions at the electrolyte-electrode interface intensify, accelerating capacity decay.

[0004] Existing technologies often employ single methods to improve battery performance, such as coating the separator surface with an oxide solid electrolyte coating to enhance thermal stability, or adjusting the electrolyte formulation to improve low-temperature performance. However, these methods often address one aspect at the expense of another, making it difficult to achieve synergistic optimization of multiple performance characteristics.

[0005] Therefore, there is an urgent need to develop a battery that combines excellent thermal shock safety with high and low temperature cycling performance. Summary of the Invention

[0006] To address or partially address the problems existing in related technologies, this application provides a battery and an electrical device that exhibit excellent thermal shock safety and high and low temperature cycling performance.

[0007] The first aspect of this application provides a battery, wherein the battery includes a positive electrode, a negative electrode, a separator, and an electrolyte; The positive electrode sheet includes a positive current collector and a positive active material layer coated on at least one side of the positive current collector, wherein the positive active material in the positive active material layer includes aluminum. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on at least one side of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material; The diaphragm includes a base membrane and an oxide solid electrolyte coating disposed on at least one side of the base membrane; The electrolyte comprises a solvent, an additive, and a lithium salt; the solvent comprises a first solvent and a second solvent; the additive comprises a first additive and a second additive; the first solvent comprises propylene carbonate and / or ethylene carbonate, and the second solvent comprises ethyl 2,2-difluoroacetate and / or trifluoroethyl methyl carbonate; the first additive comprises mannitol sulfate, and the second additive comprises ethylene sulfate. 0.08≤(A+C+D)×10000 / X≤0.77; 0.05≤(C+D)×100 / (B+W)≤2.77; 3.23≤(C+H) / B≤63.97; Wherein, the mass percentage of the first solvent in the electrolyte is A; the mass percentage of the second solvent in the electrolyte is B; the mass percentage of the first additive in the electrolyte is C; the mass percentage of the second additive in the electrolyte is D; the thickness of the oxide solid electrolyte coating is H, in μm; the mass content of aluminum in the positive electrode active material is X, in ppm; and the specific surface area of ​​the negative electrode active material is W, in m². 2 / g.

[0008] The battery as described in the first aspect, wherein the battery satisfies the following conditions: 0.10≤(A+C+D)×10000 / X≤0.60; And / or, 0.10≤(C+D)×100 / (B+W)≤2.61; And / or, 3.47≤(C+H) / B≤40.40.

[0009] The battery as described in the first aspect, wherein the battery satisfies the following conditions: 5% ≤ A ≤ 30%; And / or, 5% ≤ B ≤ 30%; And / or, 0.5% ≤ C ≤ 4%; And / or, 0.3% ≤ D ≤ 2%; And / or, 0.5 ≤ H ≤ 4; And / or, 3000≤X≤12000; And / or, 1≤W≤30.

[0010] The battery as described in the first aspect, wherein the battery satisfies the following conditions: 10%≤A≤20%; And / or, 10% ≤ B ≤ 20%; And / or, 1% ≤ C ≤ 3%; And / or, 0.5% ≤ D ≤ 1.5%; And / or, 1≤H≤3; And / or, 5000≤X≤10000; And / or, 4≤W≤20.

[0011] As described in the first aspect, the battery wherein the oxide solid electrolyte coating comprises an oxide solid electrolyte; the oxide solid electrolyte comprises lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconate (LLZO), lithium aluminum germanium phosphate (LAGP), lithium lanthanum titanate (LLTO), and Li. 14 At least one of Zn(GeO4)4 (LISICON).

[0012] The battery as described in the first aspect, wherein the oxide solid electrolyte has a mass percentage content of 80% to 99% in the oxide solid electrolyte coating.

[0013] The battery as described in the first aspect, wherein the oxide solid electrolyte coating includes a binder comprising polyvinylidene fluoride and / or polymethyl methacrylate; Preferably, the binder has a mass percentage content of 1% to 20% in the oxide solid electrolyte coating.

[0014] The battery as described in the first aspect, wherein the positive electrode active material comprises a transition metal lithium oxide; the chemical formula of the transition metal lithium oxide is Li. 1+x Ni y Co z M (1-y-z) O2, wherein -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; M is selected from at least one of Mg, Zn, Ga, Ba, Al, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

[0015] The battery as described in the first aspect, wherein the negative electrode active material includes at least one of graphite, silicon-carbon composite material and lithium metal.

[0016] A second aspect of this application provides an electrical device, wherein the electrical device includes a battery as described in the first aspect.

[0017] The technical solution provided in this application can include the following beneficial effects: This application achieves synergistic effects by combining the first additive, the second additive, the first solvent, the second solvent, the aluminum doping in the positive electrode active material, the oxide solid electrolyte coating of the separator, and the specific surface area of ​​the negative electrode active material. By simultaneously controlling (A+C+D)×10000 / X, (C+D)×100 / (B+W), and (C+H) / B within a reasonable range, a stable SEI film and CEI film can be constructed to protect the positive and negative electrodes, stabilize the layered structure of the positive electrode active material, avoid the dissolution of transition metals and the oxidative decomposition of the electrolyte, improve the ionic conductivity of the electrolyte at low temperatures, and effectively block the positive and negative electrodes, thereby enabling the battery to exhibit excellent thermal shock safety and high and low temperature cycle performance.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Detailed Implementation

[0019] To facilitate understanding of this application, it will be described in detail below. However, before describing this application in detail, it should be understood that this application is not limited to the specific embodiments described. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be restrictive.

[0020] Where a numerical range is provided, it should be understood that every intermediate value between the upper and lower limits of the range and any other specified or intermediate value within the specified range is covered within this application. The upper and lower limits of these smaller ranges may be independently included in the smaller range and are also covered within this application, subject to any explicitly excluded limits within the specified range. Where the specified range includes one or two limits, the range excluding any or both of those included limits is also included within this application.

[0021] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While the methods and materials described herein, or any equivalent methods and materials, may also be used in the implementation or testing of this application, preferred methods and materials are now described.

[0022] Lithium-ion batteries still face a series of challenges in practical applications: Under extreme thermal abuse conditions (such as thermal shock), traditional liquid electrolytes are prone to decomposition and gas production, posing a risk of thermal runaway; at low temperatures (0°C), electrolyte viscosity increases and ionic conductivity decreases, leading to a sharp decline in battery cycle performance and rate performance; during long-term cycling at high temperatures (45°C), side reactions at the electrolyte-electrode interface intensify, accelerating capacity decay.

[0023] To address the aforementioned problems, this application provides a battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a positive current collector and a positive active material layer coated on at least one side of the positive current collector, wherein the positive active material layer comprises aluminum. The negative electrode includes a negative current collector and a negative active material layer coated on at least one side of the negative current collector, wherein the negative active material layer comprises a negative active material. The separator includes a base film and an oxide solid electrolyte coating disposed on at least one side of the base film. The electrolyte comprises a solvent, an additive, and a lithium salt. The solvent includes a first solvent and a second solvent. The additive includes a first additive and a second additive. The first solvent includes propylene carbonate (PC) and / or ethylene carbonate (EC), and the second solvent includes ethyl 2,2-difluoroacetate (DFEA) and / or trifluoroethyl methyl carbonate (FEMC). The first additive includes mannitol sulfate (CBS), and the second additive includes ethylene sulfate (DTD).

[0024] This application does not limit the choice of the positive electrode current collector; it can be any known material suitable for use as a positive electrode current collector, including aluminum, stainless steel, nickel plating, titanium, tantalum metal materials, carbon cloth, carbon paper, etc. This application does not limit the choice of the positive electrode active material; it can be selected according to actual needs. For example, lithium transition metal oxides can be used as the positive electrode active material. The positive electrode active material of this application includes aluminum element, which is coated on the surface of the positive electrode active material. The positive electrode active material layer of this application includes the positive electrode active material, a conductive agent, and a binder. Both the conductive agent and the binder in the positive electrode active material layer of this application can be selected from conventional materials in the art.

[0025] This application does not limit the selection of the negative electrode current collector. For example, the negative electrode current collector can be copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or composite current collectors. This application does not limit the selection of the negative electrode active material; it can be selected according to actual needs. For example, natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, and soft carbon can be used as the negative electrode active material. The negative electrode active material layer of this application includes the negative electrode active material, a conductive agent, and a binder. Both the conductive agent and the binder in the negative electrode active material layer of this application can be selected from conventional materials in the art.

[0026] This application does not limit the choice of the base membrane; for example, the base membrane can be a polyethylene diaphragm, a polypropylene diaphragm, etc. The oxide solid electrolyte coating of this application includes an oxide solid electrolyte. This application does not limit the choice of the oxide solid electrolyte; for example, the oxide solid electrolyte can be lithium aluminum titanium phosphate, lithium lanthanum zirconate, lithium aluminum germanium phosphate, etc.

[0027] The electrolyte of this application comprises a solvent, an additive, and a lithium salt. The solvent comprises a first solvent and a second solvent, wherein the first solvent comprises propylene carbonate (PC) and / or ethylene carbonate (EC), and the second solvent comprises ethyl 2,2-difluoroacetate (DFEA) and / or trifluoroethyl methyl carbonate (FEMC). The additive comprises a first additive and a second additive, wherein the first additive comprises mannitol sulfate (CBS), and the second additive comprises ethylene sulfate (DTD). The first additive, the second additive, and the lithium salt are dissolved in a solvent composed of the first solvent and the second solvent to form the electrolyte.

[0028] The first additive (CBS), as a multifunctional film-forming additive, has sulfate and carbonate groups in its molecular structure that can be preferentially reduced on the negative electrode surface to form a dense and robust SEI film rich in inorganic components such as Li2SO3 and Li2CO3. This greatly inhibits the side reactions between the electrolyte and active materials at high temperatures, thus significantly improving thermal shock safety.

[0029] The second additive (DTD), as a film-forming additive at the cathode interface, can form a stable CEI film with good ionic conductivity on the cathode surface, effectively inhibiting the oxidative decomposition of the electrolyte and the dissolution of transition metal ions, thereby improving the cycle stability of the battery.

[0030] The first solvent (PC, EC) has a low melting point, good low-temperature fluidity, and a high reduction potential, which can participate in the formation of the SEI film and improve the low-temperature and early-stage cycling performance of the battery.

[0031] The second solvent (DFEA, FEMC) contains fluorine atoms, has low viscosity and certain flame retardancy, and can effectively improve the ionic conductivity of the electrolyte at low temperatures, thereby enhancing the low-temperature performance of the battery. Aluminum doping in the positive electrode active material allows aluminum to enter the crystal lattice, stabilizing the layered structure, suppressing phase transitions and oxygen release at high temperatures, thus improving the intrinsic thermal stability of the positive electrode active material and ensuring the cycle stability of the battery.

[0032] Oxide solid electrolyte coatings have excellent thermal stability and mechanical strength, and can effectively physically block the positive and negative electrodes and suppress lithium dendrite puncture, thus serving as a thermal safety barrier and improving the thermal shock safety of batteries.

[0033] The battery in this application meets the following conditions: 0.08≤(A+C+D)×10000 / X≤0.77; 0.05≤(C+D)×100 / (B+W)≤2.77; 3.23≤(C+H) / B≤63.97; Wherein, the mass percentage of the first solvent in the electrolyte is A; the mass percentage of the second solvent in the electrolyte is B; the mass percentage of the first additive in the electrolyte is C; the mass percentage of the second additive in the electrolyte is D; the thickness of the oxide solid electrolyte coating is H, in μm; the mass content of aluminum in the positive electrode active material is X, in ppm; and the specific surface area of ​​the negative electrode active material is W, in m². 2 / g.

[0034] For example, (A+C+D)×10000 / X can be 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.77, etc.

[0035] For example, (C+D)×100 / (B+W) can be 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 2.77, etc.

[0036] For example, (C+H) / B can be 3.23, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 63.97, etc.

[0037] Based on experience and experimental findings, (A+C+D)×10000 / X comprehensively regulates the balance between the total amount of the main film-forming components (PC, EC, CBS, DTD) in the electrolyte and the aluminum doping amount (X) in the positive electrode active material. The numerator (A+C+D) represents the total amount of key components involved in constructing the stable SEI film (PC, EC, CBS) and CEI film (DTD), while the denominator X represents the degree to which the positive electrode crystal structure is stabilized through aluminum doping. If (A+C+D)×10000 / X < 0.08, it indicates that the total amount of film-forming components (PC, EC, CBS, DTD) is relatively insufficient or the aluminum doping amount (X) is too high, resulting in insufficient interface protection or positive electrode capacity loss, and a decrease in thermal shock performance and cycle life. When (A+C+D)×10000 / X > 0.77, it indicates that the film-forming components are excessive or the aluminum doping amount is too low, which easily leads to the formation of an excessively thick interface film, increasing impedance, and insufficient positive electrode structural stability, resulting in performance deterioration during thermal shock and long-term cycling.

[0038] The formula (C+D)×100 / (B+W) precisely matches the synergistic relationship between film-forming additives (CBS, DTD), low-temperature functional solvents (DFEA, FEMC), and the negative electrode active material (W). The numerator (C+D) represents the total amount of core additives needed to form a high-quality interfacial film. In the denominator, B (DFEA, FEMC) provides excellent low-temperature ionic conductivity, and W (the specific surface area of ​​the negative electrode active material) determines the number of reactive sites. If (C+D)×100 / (B+W) < 0.05, it indicates that the total amount of film-forming additives (CBS, DTD) is insufficient relative to the low-temperature solvent (B) and the negative electrode reaction interface (W), resulting in poor interfacial film quality and prominent high-temperature side reactions and low-temperature impedance issues. When (C+D)×100 / (B+W) > 2.77, it indicates excessive additives or insufficient B and W, which can lead to an excessively thick interfacial film, altered electrolyte properties, and severely impaired low-temperature rate performance and long-term cycle life.

[0039] The (C+H) / B ratio defines the proportional relationship between the thermal stability enhancement components (negative electrode film-forming additive CBS and separator thermal barrier coating H) and the relatively thermally unstable low-temperature solvents (DFEA, FEMC). C and H together construct the thermal stability protective layer inside the battery (negative electrode interface) and outside (separator). However, DFEA and FEMC are prone to decomposition at high temperatures. If the battery's thermal stability protection is insufficient, it will lead to the degradation of the battery's electrochemical performance. If (C+H) / B < 3.23, it indicates that the thermal stability enhancement components (CBS, H) are insufficient to suppress the decomposition of the thermally unstable solvents DFEA and FEMC (B), resulting in poor thermal shock safety. When (C+H) / B > 63.97, it indicates that the coating is too thick (H is too large) or DFEA and FEMC are too few (B is too small). Although the thermal safety is high, the solid-phase ion transport impedance increases significantly, seriously sacrificing the battery's power performance and cycle life.

[0040] This application achieves a synergistic effect by combining the first additive, the second additive, the first solvent, the second solvent, the aluminum doping in the positive electrode active material, the oxide solid electrolyte coating of the separator, and the specific surface area of ​​the negative electrode active material. By simultaneously controlling (A+C+D)×10000 / X, (C+D)×100 / (B+W), and (C+H) / B within reasonable ranges, stable SEI and CEI films can be constructed to protect the positive and negative electrodes, stabilize the layered structure of the positive electrode active material, prevent the dissolution of transition metals and the oxidative decomposition of the electrolyte, improve the ionic conductivity of the electrolyte at low temperatures, and effectively block the positive and negative electrodes, thereby enabling the battery to exhibit excellent thermal shock safety and high and low temperature cycling performance.

[0041] In one specific implementation, the battery satisfies the following conditions: 0.10≤(A+C+D)×10000 / X≤0.60; And / or, 0.10≤(C+D)×100 / (B+W)≤2.61; And / or, 3.47≤(C+H) / B≤40.40.

[0042] For example, (A+C+D)×10000 / X can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, etc.

[0043] For example, (C+D)×100 / (B+W) can be 0.1, 0.5, 1, 1.5, 2, 2.5, 2.61, etc.

[0044] For example, (C+H) / B can be 3.47, 5, 10, 15, 20, 25, 30, 35, 40, 40.4, etc.

[0045] When (A+C+D)×10000 / X, (C+D)×100 / (B+W), and (C+H) / B are within the above ranges, the relationship between the positive electrode structure stability, electrolyte composition, negative electrode characteristics, and separator interface coating can be further synergistically controlled, resulting in better thermal shock safety and high and low temperature cycle performance of the battery.

[0046] In one specific embodiment, 5% ≤ A ≤ 30%, for example, A can be 5%, 10%, 15%, 20%, 25%, 30%, etc. When A is within the above range, the content of the first solvent is moderate, which can utilize its low-temperature advantage to participate in film formation, without causing excessive reduction on the negative electrode surface due to excessive content, leading to gas expansion and reduced SEI film stability, thereby resulting in better electrochemical performance of the battery. Preferably, 10% ≤ A ≤ 20%.

[0047] In one specific embodiment, 5% ≤ B ≤ 30%, for example, B can be 5%, 10%, 15%, 20%, 25%, 30%, etc. When B is within the above range, the content of the second solvent is moderate, which can both play its role in improving low-temperature conductivity and avoid excessive decomposition and generation of flammable gases due to excessive content, thus preventing excessive deterioration of thermal stability. This allows the battery to further balance low-temperature performance and thermal shock safety. Preferably, 10% ≤ B ≤ 20%.

[0048] In one specific embodiment, 0.5% ≤ C ≤ 4%, for example, C can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, etc. When C is within the above range, the CBS content is moderate, sufficient to form a stable SEI film to ensure thermal safety, without causing excessive low-temperature resistance due to excess, thus improving the thermal shock safety and low-temperature performance of the battery. Preferably, 1% ≤ C ≤ 3%.

[0049] In one specific embodiment, 0.3% ≤ D ≤ 2%, for example, D can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, etc. When D is within the above range, the DTD content is moderate, which can form a stable CEI film on the positive electrode surface, inhibiting transition metal dissolution and electrolyte oxidation, without excessively increasing the electrolyte viscosity, further ensuring the high and low temperature cycle performance of the battery. Preferably, 0.5% ≤ D ≤ 1.5%.

[0050] In one specific embodiment, 0.5 ≤ H ≤ 4, for example, H can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, etc. When H is within the above range, the oxide solid electrolyte coating thickness is moderate, which can provide an effective thermal barrier and lithium dendrite suppression effect without seriously hindering ion transport, thereby better improving the battery's thermal shock safety and high and low temperature cycling performance. Preferably, 1 ≤ H ≤ 3.

[0051] In one specific embodiment, 3000 ≤ X ≤ 12000, for example, X can be 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, etc. When X is within the above range, the aluminum doping amount in the positive electrode active material is moderate, achieving a good balance between stable structure and capacity maintenance. Preferably, 5000 ≤ X ≤ 10000.

[0052] In one specific embodiment, 1 ≤ W ≤ 30, for example, W can be 1, 5, 10, 15, 20, 25, 30, etc. When W is within the above range, the specific surface area of ​​the negative electrode active material is moderate, which can take into account both low-temperature reaction kinetics and interfacial side reaction control, providing more reactive sites for the battery, shortening the lithium-ion insertion / extraction path, and avoiding excessive contact area with the electrolyte, resulting in better electrochemical performance of the battery. Preferably, 4 ≤ W ≤ 20.

[0053] In one specific embodiment, the oxide solid electrolyte coating includes an oxide solid electrolyte; the oxide solid electrolyte includes lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconate (LLZO), lithium aluminum germanium phosphate (LAGP), lithium lanthanum titanate (LLTO), and Li. 14 At least one of Zn(GeO4)4 (LISICON). Using the aforementioned oxide solid electrolyte provides a suitable ion transport channel for the oxide solid electrolyte coating, supporting the rapid movement of lithium ions at low migration barriers. This improves ion transport efficiency while ensuring effective thermal barrier and lithium dendrite suppression, thereby enhancing the battery's thermal shock safety and high / low temperature cycling performance.

[0054] In one specific embodiment, the oxide solid electrolyte in the oxide solid electrolyte coating has a mass percentage content of 80% to 99%, for example, the mass percentage content of the oxide solid electrolyte can be 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, etc. When the content of the oxide solid electrolyte is within the above range, the oxide solid electrolyte coating has excellent ion transport capability, which can further improve the thermal shock safety and high and low temperature cycling performance of the battery.

[0055] In one specific embodiment, the oxide solid electrolyte coating includes a binder comprising polyvinylidene fluoride (PVDF) and / or polymethyl methacrylate (PMMA). Introducing a binder into the oxide solid electrolyte coating enhances interparticle bonding, improves electrode / electrolyte interface contact, and improves the coating's mechanical integrity. PVDF, with its strongly polar CF bonds, provides excellent electrochemical stability and adhesion to inorganic fillers, while PMMA, due to its high dielectric constant and flexible chain structure, helps wet the electrolyte particle surface, promotes lithium salt dissociation, and buffers volume changes. Both form a continuous polymer network between the oxide solid electrolyte particles through solution film formation, maintaining ion conduction pathways while improving coating flexibility and interfacial compatibility, thus ensuring battery safety and cycle performance.

[0056] In one specific embodiment, the binder content in the oxide solid electrolyte coating is 1% to 20% by mass. For example, the binder content can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc. When the binder content is within the above range, the mechanical integrity and ion transport performance of the oxide solid electrolyte coating can be balanced. If the binder content is too low, the bonding force between the oxide solid electrolyte particles is insufficient, leading to easy cracking and poor interfacial contact in the oxide solid electrolyte coating. If the content is too high, it will encapsulate the oxide solid electrolyte particles, blocking the lithium ion conduction path, significantly increasing interfacial impedance and reducing overall ionic conductivity.

[0057] In one specific embodiment, the positive electrode active material includes a transition metal lithium oxide; the chemical formula of the transition metal lithium oxide is Li. 1+x Ni y Co z M (1-y-z)O2, wherein -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; M is selected from at least one of Mg, Zn, Ga, Ba, Al, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr. When the above compounds are selected as the positive electrode active material, the positive electrode active material can fully exert its performance and improve the electrochemical performance of the battery.

[0058] In one specific embodiment, the negative electrode active material includes at least one of graphite, silicon-carbon composite material, and lithium metal. When the above-mentioned compounds are selected as the negative electrode active material, the negative electrode active material has reasonable reaction sites, providing suitable insertion / extraction pathways for lithium ions, thereby improving the electrochemical performance of the battery.

[0059] In one specific embodiment, the electrolyte of this application includes a base solvent, which includes at least one selected from diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl propionate (EP), and propyl propionate (PP). When the organic solvent of the electrolyte is selected from the above-mentioned organic solvents, the ionic conductivity of the electrolyte is higher, which is beneficial to improving the migration rate of lithium ions. At the same time, it can improve the stability of the electrolyte, reduce the decomposition reaction of the electrolyte, and thus improve the high and low temperature performance and safety performance of the battery.

[0060] In one specific embodiment, the electrolyte of this application comprises a lithium salt, which includes at least one selected from lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium difluorooxalate borate (LiODFB). When the selection of the lithium salt and its molar content are within the above-mentioned range, the electrolyte has high conductivity and reasonable viscosity, which can ensure the high and low temperature cycling performance of the battery.

[0061] In one specific embodiment, the positive electrode active layer includes a positive electrode conductive agent, a positive electrode binder, and a solvent. This application does not limit the type of positive electrode conductive agent mentioned; any known conductive agent can be used.

[0062] In one specific embodiment, the positive electrode conductive agent mentioned in this application includes at least one of carbon materials such as natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene.

[0063] In one specific embodiment, this application does not limit the type of positive electrode binder, and any known positive electrode binder can be used.

[0064] In one specific embodiment, the positive electrode binder includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose.

[0065] In one specific embodiment, the negative electrode active material layer includes a negative electrode conductive agent, a negative electrode binder, a thickener, and a solvent.

[0066] In one specific embodiment, the negative electrode conductive agent includes at least one of carbon materials such as natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene; the negative electrode binder includes styrene-butadiene latex; the thickener includes CMC; and the solvent includes deionized water.

[0067] In one specific embodiment, this application does not have any particular limitation on the negative electrode current collector, as long as it can achieve the purpose of this application. For example, it can be copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or composite current collector, etc.

[0068] In one specific embodiment, the negative current collector comprises copper foil.

[0069] In one specific embodiment, the outer packaging of the lithium-ion battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.

[0070] The outer packaging of lithium-ion batteries can also be a soft pack, such as a pouch. The material of the soft pack can be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0071] This application does not impose any particular restrictions on the shape of the lithium-ion battery; it can be cylindrical, square, or any other arbitrary shape.

[0072] Another embodiment of the present invention provides an electrical device including the aforementioned battery. This electrical device has advantages corresponding to the battery described above, which will not be elaborated further.

[0073] The application fields of the electrical devices in this application embodiment are not particularly limited, and can be used in consumer electronics products, new energy vehicles, and energy storage. For example, the above-mentioned electronic devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., without particular limitation.

[0074] The present application will be further described in detail below through specific embodiments.

[0075] Example 1 1. Preparation of positive electrode sheet The positive electrode current collector is a 10μm aluminum foil. The positive electrode active material (lithium cobalt oxide), with an aluminum element content of 8000ppm, is mixed evenly with the positive electrode conductive agent acetylene black (SuperP) and polyvinylidene fluoride (PVDF) binder at a mass ratio of 97:1.5:1.5. The mixture is then evenly dispersed with 1-methyl-2-pyrrolidone (NMP) to form a uniform positive electrode slurry. The positive electrode slurry is coated onto the aluminum foil current collector and then baked and rolled to obtain the positive electrode sheet.

[0076] 2. Preparation of the diaphragm The base membrane is a 6μm PE base membrane. The oxide solid electrolyte LATP, polyvinylidene fluoride (PVDF) binder, and 1-methyl-2-pyrrolidone (NMP) are mixed in a mass ratio of 50:2:48. After uniform mixing, an oxide solid electrolyte coating slurry is obtained. The coating slurry is uniformly applied to the side of the separator facing the positive electrode. After baking and rolling, the coating thickness H on one side is measured by calipers and is 2μm.

[0077] 3. Preparation of negative electrode sheet Artificial graphite (anode active material), acetylene black (SuperP) (anode conductive agent), CMC (thickener), and SBR (anode binder) (anode binder) were mixed evenly in a mass ratio of 94:2:1.2:2.8 and then uniformly dispersed with deionized water to form a uniform anode slurry. The mixed slurry was coated on both sides of a copper foil current collector, and then baked, rolled, and cut into sheets to obtain the anode sheet. The specific surface area W of the artificial graphite was 6 m² / g.

[0078] 4. Preparation of electrolyte a. Mix propyl propionate (PP) and diethyl carbonate (DEC) at a mass ratio of 15:15 to form a mixed solvent. Remove water using a molecular sieve and set aside. b. Add 1M LiPF6 and mix well to obtain the electrolyte base solution; c. Add PC, DFEA, CBS, and DTD to the electrolyte base solution at concentrations of 5%, 15%, 2%, and 1%, respectively, to obtain the final electrolyte.

[0079] 5. Manufacturing of lithium-ion batteries The prepared positive electrode, separator, and negative electrode are stacked in sequence, with the separator in the middle of the positive and negative electrode, and the oxide solid electrolyte coating facing the positive electrode. After winding and welding the tabs, a bare cell is obtained. The bare cell is placed in an aluminum-plastic film for electrolyte injection, encapsulation, secondary sealing, and capacity testing to obtain a lithium-ion battery.

[0080] Examples 2-50 and Comparative Examples 1-57 are used to illustrate the lithium-ion battery of this application, including most of the operations in Example 1, except that: the type and percentage content (A, B, C, D) of the first solvent, the second solvent, the first additive and the second additive, the thickness H of the oxide solid electrolyte coating on the separator surface, the content X of aluminum element in the positive electrode active material and the specific surface area W of the negative electrode active material are based on Table 1 and Table 2, respectively.

[0081] Table 1

[0082] Table 2

[0083] Test case The following performance tests were performed on the batteries prepared in the examples and comparative examples: 1. Thermal shock test The lithium-ion battery was charged at 25°C at a rate of 1C to the cutoff voltage with a cutoff current of 0.025C. It was then transferred to an oven and heated to 150°C at a rate of 5°C / min. The temperature was kept constant for 60 minutes. The battery was considered to have passed the test if it did not catch fire or explode. The number of battery cells tested was 20.

[0084] 2. 45℃ Cyclic Performance Test The lithium-ion battery was charged and discharged at 45°C at a rate of 1C / 1C within the charge and discharge cutoff voltage range. The discharge capacity of the first cycle was recorded as C1, and the discharge capacity of the Nth cycle was recorded as C2. The capacity of the Nth cycle was divided by the capacity of the first cycle to obtain the cycle capacity retention rate R2 = C2 / C1. The number of cycles of the lithium-ion battery when the cycle capacity retention rate R2 was 80% was recorded.

[0085] 3. 0℃ Cyclic Performance Test The lithium-ion battery was charged and discharged at 0°C at a rate of 1C / 1C within the charge and discharge cutoff voltage range. The discharge capacity of the first cycle was recorded as Y1, and the discharge capacity of the Nth cycle was recorded as Y2. The capacity of the Nth cycle was divided by the capacity of the first cycle to obtain the cycle capacity retention rate of the Nth cycle, X2 = Y2 / Y1. The cycle number of the lithium-ion battery when the cycle capacity retention rate X2 was 80% was recorded.

[0086] Table 3

[0087] As shown in Table 3: Examples 1-50 and Comparative Examples 1-31 (lacking key components): clearly demonstrate that the multi-component synergistic system of this application is indispensable. The absence of any core component (first solvent, second solvent, first additive, first additive, oxide solid electrolyte coating) leads to a severe collapse of at least one key performance characteristic. For example, Comparative Example 7 (PC and DFEA only) passed thermal shock 0; Comparative Example 4 (CBS only) only cycled for 234 cycles at 0°C.

[0088] Examples 1-35 and Comparative Examples 32-45 (parameters outside the preferred range of this invention): demonstrate that the independent range of each parameter is the basis for maintaining system balance. If any parameter exceeds its declared range, even if other parameters are normal, synergy will be disrupted, leading to overall performance degradation. For example, Comparative Example 33 (A=40%), Comparative Example 35 (B=40%), Comparative Example 37 (C=8%), Comparative Example 41 (H=8μm), Comparative Example 43 (X=20000ppm), and Comparative Example 45 (W=50m) 2 ( / g), none of them can achieve a balanced and excellent performance across the three aspects.

[0089] Examples 3 and Comparative Examples 46-50 (component substitution): demonstrate the irreplaceability and synergistic uniqueness of the specific combination of substances selected in this application (specific first solvent, specific second solvent, CBS, DTD, specific oxide solid electrolyte). Substituting other common solvents (such as PP), additives (such as MMDS, PS), or coating types (ordinary ceramics) resulted in significantly lower performance than the system in this application.

[0090] Comparative Examples 51-56 (Relation Imbalance): These examples convincingly demonstrate that merely satisfying the independent ranges of each parameter is insufficient. While some parameters in Comparative Examples 51-56 are within their ranges, the simultaneous imbalance of the three core relations leads to a comprehensive performance degradation, far below that of the implementation examples. This underscores the absolute necessity of simultaneously satisfying all three relations for achieving synergistic performance optimization.

[0091] Example 3 / 8: As an example near the center point, its parameters (A=15%, B=15% / 17%, C=2%, D=1%, H=2μm, X=8000ppm, W=6m) 2All values ​​( / g) are within the preferred range. The calculation results of the three relationships are excellent, and the corresponding performance (thermal shock 15 / 14 particles passed, 0℃ cycling 607 / 609 cycles, 45℃ cycling 575 / 544 cycles) is comprehensive, balanced and leading, demonstrating the best synergistic effect of this application.

[0092] Examples 36-39 (Different Oxide Solid Electrolyte Types): Using various oxide solid electrolytes such as LATP, LLZO, LAGP, LISICON, and LLTO, excellent and similar performances were observed while keeping other parameters and relationships constant. This demonstrates that the core of the synergistic mechanism of this application lies in the coating thickness (H) and its synergistic effect with the electrolyte system, while being inclusive of the selection of specific oxide types. Similarly, Examples 3 and 46, and Examples 3 and 47, were compared: using EC as the first solvent and FEMC as the second solvent, excellent and similar performances were observed.

[0093] Examples 40-45 (Boundary Examples): The parameters in these examples ensure that one or more relational values ​​lie within the boundaries of this patent claim (e.g., (A+C+D)×10000 / X=0.08 in Example 40, (C+H) / B=63.97 in Example 45). While their performance is slightly inferior to the central examples, it is still significantly and comprehensively superior to the vast majority of comparative examples, which strongly demonstrates the validity and rationality of the scope of relations claimed in this invention.

[0094] Examples 48-50 and Comparative Example 57: The mass ratio of oxide solid electrolyte in the oxide solid electrolyte coating was compared. The performance of Examples 48-50 was higher than that of Comparative Example 57, which proves the influence of the mass ratio of oxide solid electrolyte on battery performance.

[0095] In summary, this application constructs a highly synergistic lithium-ion battery system by defining: a material system with specific functional combinations (first solvent, second solvent, CBS, DTD, and oxide solid electrolyte coating); independent optimization ranges for each key parameter (A, B, C, D, H, X, W); and three multi-dimensional synergistic relationships ((A+C+D)×10000 / X, (C+D)×100 / (B+W), (C+H) / B). Only by simultaneously satisfying all the above conditions can the performance trade-off dilemma of "improving thermal safety at the expense of low-temperature performance, and improving cycle life at the expense of increased thermal risk" in traditional technologies be overcome, truly achieving simultaneous and significant improvement in thermal shock safety, low-temperature cycle life, and high-temperature cycle life. This application's solution is particularly suitable for high-end fields such as electric vehicles and large-scale energy storage systems, which have extremely high requirements for safety, environmental adaptability, and long-term reliability.

[0096] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A battery, characterized in that, The battery includes a positive electrode, a negative electrode, a separator, and an electrolyte; The positive electrode sheet includes a positive current collector and a positive active material layer coated on at least one side of the positive current collector, wherein the positive active material in the positive active material layer includes aluminum. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on at least one side of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material; The diaphragm includes a base membrane and an oxide solid electrolyte coating disposed on at least one side of the base membrane; The electrolyte comprises a solvent, an additive, and a lithium salt; the solvent comprises a first solvent and a second solvent; the additive comprises a first additive and a second additive; the first solvent comprises propylene carbonate and / or ethylene carbonate; the second solvent comprises ethyl 2,2-difluoroacetate and / or trifluoroethyl methyl carbonate; the first additive comprises mannitol sulfate; the second additive comprises ethylene sulfate. 0.08≤(A+C+D)×10000 / X≤0.77; 0.05≤(C+D)×100 / (B+W)≤2.77; 3.23≤(C+H) / B≤63.97; Wherein, the mass percentage of the first solvent in the electrolyte is A; the mass percentage of the second solvent in the electrolyte is B; the mass percentage of the first additive in the electrolyte is C; the mass percentage of the second additive in the electrolyte is D; the thickness of the oxide solid electrolyte coating is H, in μm; the mass content of aluminum in the positive electrode active material is X, in ppm; and the specific surface area of ​​the negative electrode active material is W, in m². 2 / g.

2. The battery according to claim 1, characterized in that, The battery meets the following conditions: 0.10≤(A+C+D)×10000 / X≤0.60; And / or, 0.10≤(C+D)×100 / (B+W)≤2.61; And / or, 3.47≤(C+H) / B≤40.

40.

3. The battery according to claim 1, characterized in that, The battery meets the following conditions: 5%≤A≤30%； And / or, 5% ≤ B ≤ 30%; And / or, 0.5% ≤ C ≤ 4%; And / or, 0.3% ≤ D ≤ 2%; And / or, 0.5 ≤ H ≤ 4; And / or, 3000≤X≤12000; And / or, 1≤W≤30.

4. The battery according to claim 3, characterized in that, The battery meets the following conditions: And / or, 10% ≤ A ≤ 20%; And / or, 10% ≤ B ≤ 20%; And / or, 1% ≤ C ≤ 3%; And / or, 0.5% ≤ D ≤ 1.5%; And / or, 1≤H≤3; And / or, 5000≤X≤10000; And / or, 4≤W≤20.

5. The battery according to claim 1, characterized in that, The oxide solid electrolyte coating comprises an oxide solid electrolyte; the oxide solid electrolyte includes lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconate (LLZO), lithium aluminum germanium phosphate (LAGP), lithium lanthanum titanate (LLTO), and Li. 14 At least one of Zn(GeO4)4 (LISICON).

6. The battery according to claim 5, characterized in that, The oxide solid electrolyte has a mass percentage content of 80% to 99% in the oxide solid electrolyte coating.

7. The battery according to claim 5, characterized in that, The oxide solid electrolyte coating includes a binder, which includes polyvinylidene fluoride and / or polymethyl methacrylate; Preferably, the binder has a mass percentage content of 1% to 20% in the oxide solid electrolyte coating.

8. The battery according to claim 1, characterized in that, The positive electrode active material includes a transition metal lithium oxide; the chemical formula of the transition metal lithium oxide is Li. 1+x Ni y Co z M (1-y-z) O2, wherein -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; M is selected from at least one of Mg, Zn, Ga, Ba, Al, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

9. The battery according to claim 1, characterized in that, The negative electrode active material includes at least one of graphite, silicon-carbon composite material and lithium metal.

10. An electrical device, characterized in that, The electrical device includes the battery as described in any one of claims 1 to 9.

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