A battery and an electric device

Abstract

The application provides a battery and a power utilization device, a positive electrode sheet comprises a positive electrode active material, the positive electrode active material is doped and / or coated with a lanthanum element; a separator surface is coated with a ceramic coating; an electrolyte comprises a first solvent, a second solvent, a first additive and a second additive; the first solvent comprises a cyclic carbonate compound, the second solvent comprises a chain fluorosulfonamide compound, the first additive comprises mannitol carbonic acid sulfate, and the second additive comprises succinonitrile; by doping / coating the positive electrode active material with the lanthanum element, the application can effectively inhibit the release of lattice oxygen under high voltage or high temperature, and reduce the exothermic reaction activity at the thermal runaway starting temperature; the first additive and the second additive in the electrolyte form a dense, high-thermal-stability CEI film and SEI film on the positive and negative electrode surfaces respectively; the separator ceramic coating provides a physical barrier, improves the thermal shrinkage temperature of the separator, and prevents internal short circuit.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage technology, specifically to a battery and an electrical device. Background Technology

[0002] Lithium-ion batteries, as the dominant rechargeable battery technology, have become the core power source for electric vehicles, consumer electronics, and large-scale energy storage systems due to their high energy density, long cycle life, and relatively mature industrialization. However, as application scenarios continue to expand into extreme environments (such as frigid regions, high-temperature climates, or high-power fast charging conditions), lithium-ion batteries have revealed significant shortcomings in thermal safety, low-temperature performance, and long-term cycle stability at high temperatures, severely restricting their comprehensive application performance under complex operating conditions.

[0003] In terms of thermal safety, traditional liquid electrolytes are typically composed of flammable organic solvents. Under conditions of thermal abuse such as overcharging, short circuits, mechanical damage, or external heating, they are highly susceptible to triggering a chain reaction of exothermic reactions. This leads to a sharp increase in the internal temperature of the battery, which in turn triggers a series of chain reactions, including positive electrode decomposition, negative electrode SEI film rupture, and separator melting and shrinkage. Ultimately, this can lead to thermal runaway or even fire and explosion. Although some studies have improved the thermal dimensional stability of the separator by coating the surface with inorganic ceramic layers such as alumina and silicon dioxide, or by introducing flame-retardant additives to inhibit electrolyte combustion, these strategies often focus only on local modification of a single component and fail to consider the overall thermal-electrochemical coupling mechanism of the battery for system design. Consequently, it is difficult to balance electrochemical performance and intrinsic safety.

[0004] In terms of low-temperature performance, conventional carbonate electrolytes exhibit significant increases in viscosity and decreases in ionic conductivity below 0°C. Simultaneously, the desolvation barrier of lithium ions at the electrode / electrolyte interface rises, leading to a sharp increase in interfacial charge transfer resistance, severe battery polarization, a rapid drop in capacity, and deterioration in rate capability. Although some studies have attempted to optimize the solvation structure by introducing low-melting-point cosolvents (such as fluorinated carbonates and ethers) or additives with high donor numbers, such modifications are often accompanied by decreased high-temperature stability or poor compatibility with high-voltage cathode materials, resulting in a trade-off between performance aspects.

[0005] Regarding long-term cycling stability at high temperatures, the continuous oxidative decomposition of the electrolyte on the high-potential positive electrode surface, as well as the cross-contamination of the negative electrode caused by the dissolution of transition metal ions, accelerates the degradation and reconstruction of the solid electrolyte interface (SEI) and the positive electrode electrolyte interface (CEI), leading to irreversible capacity loss and increased internal resistance. Although some functional additives (such as VC, FEC, DTD, etc.) can stabilize the interface to a certain extent, their effectiveness is highly dependent on physical parameters such as the specific surface area, compaction density, and pore structure of the electrode material. However, existing technologies lack a quantitative description of the matching relationship between electrolyte components and electrode microstructure, relying heavily on empirical trial and error, making precise control difficult.

[0006] More importantly, the three major performance pain points mentioned above—thermal safety, low-temperature kinetics, and high-temperature durability—are inherently coupled and mutually restrictive. For example, high-concentration electrolytes that improve thermal stability often have high viscosity and poor low-temperature performance; weak solvation systems that enhance low-temperature lithium conductivity may sacrifice oxidation stability; and film-forming additives used to stabilize high-temperature interfaces may form high-resistivity interface layers at low temperatures. Traditional R&D paradigms typically optimize a single component (such as the separator, electrolyte, or electrode) in isolation, lacking a deep understanding of the synergistic design and cross-scale correlation mechanisms of the battery's "electrolyte-electrode-separator" multiphase interface system, making it difficult to overcome the technical bottleneck of "single-item improvement, overall limitation."

[0007] Therefore, there is an urgent need to develop a design scheme that can systematically integrate and quantitatively correlate electrolyte chemistry, electrode material properties, and membrane structure parameters, so as to fundamentally break through the industry bottleneck of the difficulty in synergistically optimizing the thermal safety, low-temperature performance, and high-temperature long life of lithium-ion batteries. Summary of the Invention

[0008] In view of the problem that existing lithium-ion batteries cannot be comprehensively improved in terms of safety, low-temperature kinetics and high-temperature durability, this invention provides a battery and an electrical device.

[0009] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0010] In one aspect, the present invention provides a battery comprising:

[0011] A positive electrode sheet, comprising a positive current collector and a positive active material layer disposed on the positive current collector, the positive active material layer comprising a positive active material, the positive active material being doped with and / or coated with lanthanum; the mass content of lanthanum in the positive active material layer is X ppm, the value of X being in the range of 400-2500;

[0012] The negative electrode includes a negative current collector and a negative active material layer disposed on the negative current collector; the specific surface area of ​​the negative active material layer is W m². 2 / g, where W ranges from 1 to 30; the compaction density of the negative electrode active material layer is Y g / cm³. 3 The value of Y ranges from 1 to 2.2;

[0013] A diaphragm, comprising a base membrane and a ceramic coating coated on the surface of the base membrane; the thickness of the ceramic coating is H μm, wherein the value of H ranges from 0.5 to 5; the porosity of the base membrane is P %, wherein the value of P ranges from 20 to 70.

[0014] An electrolyte comprising a first solvent, a second solvent, a first additive, and a second additive; the first solvent comprises a cyclic carbonate compound, the second solvent comprises a chain-like fluorosulfonamide compound, the first additive comprises mannitol sulfate, and the second additive comprises succinate; the total mass of the electrolyte is denoted as 100%, the mass percentage of the first solvent in the electrolyte is denoted as A%, where A ranges from 5 to 40%; the mass percentage of the second solvent in the electrolyte is denoted as B%, where B ranges from 5 to 40%; the mass percentage of the first additive in the electrolyte is denoted as C%, where C ranges from 0.5 to 5%; and the mass percentage of the second additive in the electrolyte is denoted as D%, where D ranges from 0.4 to 10%.

[0015] The values ​​A, B, C, D, X, W, Y, H, and P satisfy the following condition:

[0016] Equation 1: 0.34 ≤ (A+C+D)*100 / X ≤ 9.24;

[0017] Equation 2: 0.19≤(C+D)*10 / (B / 100+W+P)≤2.48;

[0018] Equation 3: 2.67≤(C*0.01+H) / (B*0.01)≤77.43;

[0019] Equation 4: 11.90≤P / Y≤54.17.

[0020] Optionally, the values ​​of A, B, C, D, X, W, Y, H, and P satisfy the following conditions:

[0021] Equation 5: 0.56 ≤ (A+C+D)*100 / X ≤ 4.75;

[0022] Equation 6: 0.29 ≤ (C+D)*10 / (B / 100+W+P) ≤ 2.39;

[0023] Equation 7: 3.47≤(C*0.01+H) / (B*0.01)≤40.40;

[0024] Equation 8: 12.50≤P / Y≤45.00.

[0025] Optionally, the value range of A is 10-30; the value range of B is 10-30; the value range of C is 1-3; the value range of D is 1.2-6; the value range of H is 1.5-3; the value range of P is 30-60; the value range of X is 1000-2000; the value range of W is 4-20; and the value range of Y is 1.4-2.

[0026] Optionally, the cyclic carbonate compound includes one or more of ethylene carbonate and propylene carbonate.

[0027] Optionally, the chain-like fluorosulfonamide compound includes one or more of dimethylaminosulfonyl fluoride, 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, and N,N-diethylaminosulfonyl fluoride.

[0028] Optionally, the positive electrode active material further includes transition metal lithium oxides doped with and / or coated with lanthanum.

[0029] Optionally, the chemical formula of the transition metal lithium oxide is Li 1+x Ni y Co z M (1-y-z) O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1;

[0030] M is selected from one or more of Mg, Zn, Ga, Ba, Al, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

[0031] Optionally, the ceramic coating includes one or more of alumina, aluminum hydroxide, boehmite, titanium dioxide, and silicon dioxide.

[0032] Optionally, the negative electrode active material layer includes a negative electrode active material, which includes one or more of graphite, silicon-carbon composite material, or lithium metal material.

[0033] Another aspect of the present invention provides an electrical device comprising the battery described above.

[0034] According to the battery provided by the present invention, by doping / coating the positive electrode active material with lanthanum, the release of lattice oxygen under high voltage or high temperature can be effectively suppressed, thereby reducing the exothermic reaction activity at the thermal runaway initiation temperature; the first additive (mannitol carbonate sulfate) and the second additive (succinate) in the electrolyte form a dense and highly thermally stable CEI film and SEI film on the positive and negative electrode surfaces, respectively; the ceramic coating of the separator provides a physical barrier, increases the thermal shrinkage temperature of the separator, and prevents internal short circuits.

[0035] Equation 1: 0.34≤(A+C+D)*100 / X≤9.24 precisely matches the interfacial film-forming resources (A+C+D) with the cathode stability requirements (X), avoiding insufficient protection or excessively high film resistance;

[0036] Equation 2: 0.19≤(C+D)*10 / (B / 100+W+P)≤2.48 precisely matches the total amount of functional additives (C+D) with the ion transport channels (B+W+P) to avoid excessive additives leading to interface passivation or insufficient additives leading to side reactions.

[0037] Equation 3: 2.67≤(C*0.01+H) / (B*0.01)≤77.43 ensures that while using fluorosulfonamide solvents, a sufficiently strong positive electrode side protection is constructed through mannitol carbonate sulfate and ceramic coating to effectively suppress electrolyte decomposition and gas generation and heat release at high temperatures.

[0038] Equation 4: 11.90≤P / Y≤54.17 Coordinating the ion channel (P) of the membrane with the negative electrode compaction density (Y), at high energy density (Y≥1g / cm³). 3 Under the premise of maintaining sufficient pore connectivity, it avoids ion diffusion obstruction due to excessive compaction, thus enabling it to have excellent low-temperature discharge performance.

[0039] CBS and SN synergistically form a compound rich in inorganic components (such as LiF, Li) at high temperatures. x SO y The stable CEI / SEI film effectively blocks continuous oxidation of the electrolyte and dissolution of transition metals. Lanthanum doping further inhibits the degradation of the positive electrode structure, reduces the dissolution of metal ions such as Mn / Ni / Co, and prevents them from migrating to the negative electrode and damaging the SEI. The electrolyte components are designed for anti-aging. Although the fluorinated solvent is easily oxidized, the ratio of its amount (B) to the protective strength (C+H) is constrained by Equation 3 to ensure that it does not undergo severe decomposition during long-term cycling at high temperatures.

[0040] This invention introduces specific material systems into the four core components of the battery—positive electrode, negative electrode, separator, and electrolyte—and constructs a closed-loop collaborative design mechanism by combining four key parameter relationships (Equations 1-4), thereby achieving significant improvements in battery performance in terms of thermal shock safety, low-temperature discharge performance, and high-temperature cycle stability. Detailed Implementation

[0041] To make the technical problems solved, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0042] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0043] In one embodiment, the present invention provides a battery comprising:

[0044] A positive electrode sheet, comprising a positive current collector and a positive active material layer disposed on the positive current collector, the positive active material layer comprising a positive active material, the positive active material being doped with and / or coated with lanthanum; the mass content of lanthanum in the positive active material layer is X ppm, the value of X being in the range of 400-2500;

[0045] The negative electrode includes a negative current collector and a negative active material layer disposed on the negative current collector; the specific surface area of ​​the negative active material layer is Wm². 2 / g, where W ranges from 1 to 30; the compaction density of the negative electrode active material layer is Y g / cm³. 3 The value of Y ranges from 1 to 2.2;

[0046] A diaphragm, comprising a base membrane and a ceramic coating coated on the surface of the base membrane; the thickness of the ceramic coating is H μm, wherein the value of H ranges from 0.5 to 5; the porosity of the base membrane is P%, wherein the value of P ranges from 20 to 70.

[0047] An electrolyte comprising a first solvent, a second solvent, a first additive, and a second additive; the first solvent comprises a cyclic carbonate compound, the second solvent comprises a chain-like fluorosulfonamide compound, the first additive comprises mannitol sulfate, and the second additive comprises succinate; the total mass of the electrolyte is denoted as 100%, the mass percentage of the first solvent in the electrolyte is denoted as A%, where A ranges from 5 to 40%; the mass percentage of the second solvent in the electrolyte is denoted as B%, where B ranges from 5 to 40%; the mass percentage of the first additive in the electrolyte is denoted as C%, where C ranges from 0.5 to 5%; and the mass percentage of the second additive in the electrolyte is denoted as D%, where D ranges from 0.4 to 10%.

[0048] The values ​​A, B, C, D, X, W, Y, H, and P satisfy the following condition:

[0049] Equation 1: 0.34 ≤ (A+C+D)*100 / X ≤ 9.24;

[0050] Equation 2: 0.19≤(C+D)*10 / (B / 100+W+P)≤2.48;

[0051] Equation 3: 2.67≤(C*0.01+H) / (B*0.01)≤77.43;

[0052] Equation 4: 11.90≤P / Y≤54.17.

[0053] Specifically, the mass content of lanthanum in the positive electrode active material layer is any one value or a range of any two values ​​from 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 1100ppm, 1200ppm, 1300ppm, 1400ppm, 1500ppm, 1600ppm, 1700ppm, 1800ppm, 1900ppm, 2000ppm, 2100ppm, 2200ppm, 2300ppm, 2400ppm, or 2500ppm.

[0054] When the mass content of lanthanum in the positive electrode active material layer is 400ppm-2500ppm, lanthanum can effectively enter the positive electrode lattice or form a surface coating layer, stabilizing the crystal structure, inhibiting oxygen evolution, and reducing interfacial side reactions, while not significantly hindering lithium-ion diffusion. When the mass content of lanthanum in the positive electrode active material layer is less than 400ppm, the doping / coating amount of lanthanum is insufficient, making it difficult to effectively inhibit the structural collapse and transition metal dissolution of the positive electrode material under high voltage or high temperature, resulting in a decrease in thermal stability and cycle life. When the mass content of lanthanum in the positive electrode active material layer is greater than 2500ppm, excessive lanthanum will form insulating oxide agglomerates on the particle surface, increasing interfacial impedance, reducing rate performance, and may block lithium-ion transport channels, thus impairing electrochemical performance.

[0055] Specifically, the specific surface area of ​​the negative electrode active material layer is 1m². 2 / g、4m 2 / g、8m 2 / g、12m 2 / g, 16m 2 / g、20m 2 / g、24m 2 / g、27m 2 / g or 30m 2 Any single value or a range of any two values ​​in / g.

[0056] When the specific surface area of ​​the negative electrode active material layer is 1-30m² 2 / g, which can provide sufficient electrochemical reaction active sites to support rapid charge and discharge, while avoiding excessively high initial irreversible capacity or excessive SEI film growth due to excessive specific surface area; when the specific surface area of ​​the negative electrode active material layer is less than 1m 2 At a density of / g, the material surface is too dense, resulting in slow lithium-ion insertion / extraction kinetics and significant degradation in battery rate performance and low-temperature performance; when the specific surface area of ​​the negative electrode active material layer is greater than 30m², the lithium-ion insertion / extraction kinetics are slow. 2 At a specific surface area of ​​ / g, an excessively high specific surface area will cause a large amount of electrolyte to decompose in the first cycle, forming a thick SEI film, resulting in loss of active lithium, reduced coulombic efficiency, and increased risk of gas production and cycle expansion.

[0057] Specifically, the compaction density of the negative electrode active material layer is 1 g / cm³. 3 1.1g / cm 3 1.2g / cm 3 1.3g / cm 3 1.4g / cm 3 1.5g / cm 3 1.6g / cm 3 1.7g / cm 3 1.8g / cm 3 1.9g / cm 3 2g / cm 3 2.1g / cm 3 Or 0.2g / cm 3 The range of values ​​consisting of any one point value or any two point values.

[0058] When the compaction density of the negative electrode active material layer is 1-2.2 g / cm³ 3 Maintaining a reasonable pore structure while ensuring high volumetric energy density is beneficial for electrolyte wetting and lithium-ion diffusion; when the compaction density of the negative electrode active material layer is less than 1 g / cm³ 3 When the electrode is too porous, the volumetric energy density decreases significantly, and poor interparticle contact leads to a decline in electron conductivity; when the compaction density of the negative electrode active material layer exceeds 2.2 g / cm³... 3 When the electrode porosity is excessively compressed, the electrolyte cannot fully wet the electrolyte, the lithium-ion solid-phase diffusion path is blocked, and polarization increases sharply, especially at low temperature or high rate conditions, resulting in deterioration of cycle stability.

[0059] Specifically, the thickness of the ceramic coating is any one value or a range of any two values ​​from 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, and 5μm.

[0060] When the thickness of the ceramic coating is 0.5-5μm, it can effectively improve the thermal stability, mechanical strength and electrolyte affinity of the separator without significantly increasing the overall thickness of the separator, while maintaining good ion permeability. When the thickness of the ceramic coating is less than 0.5μm, the coating coverage is discontinuous and cannot effectively prevent the separator from shrinking and deforming at high temperatures, resulting in insufficient thermal runaway protection. When the thickness of the ceramic coating is greater than 5μm, the excessive coating thickness will block the original pores of the separator, reduce pore connectivity, increase ion transport resistance, and lead to an increase in battery internal resistance and a decrease in rate performance.

[0061] Specifically, the porosity of the base membrane is any one value or a range of any two values ​​from 20%, 30%, 40%, 50%, 60%, or 70%.

[0062] When the porosity of the base membrane is 20-70%, it can ensure sufficient electrolyte storage space and ion migration channels, while maintaining the mechanical integrity and safety of the diaphragm. When the porosity of the base membrane is less than 20%, there are too few pores, and the ionic conductivity is significantly reduced, especially at low temperature or high current density, which can easily lead to severe concentration polarization. When the porosity of the base membrane is greater than 70%, the diaphragm skeleton is too weak, the mechanical strength decreases, and it is easy to perforate or short-circuit during winding or cycling, and it is more prone to thermal shrinkage at high temperature.

[0063] Specifically, the mass percentage of the first solvent in the electrolyte is any one of the following values, or a range of any two values: 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%.

[0064] When the first solvent accounts for 5%–40% of the electrolyte by mass, cyclic carbonates (such as EC and PC) can provide sufficient dielectric constant to promote lithium salt dissociation and participate in the formation of a stable SEI film, while avoiding a sharp increase in viscosity at low temperatures due to an excessively high proportion. When the first solvent accounts for less than 5% of the electrolyte by mass, lithium salt dissociation is insufficient, ionic conductivity is low, and it is difficult to form an effective SEI at the negative electrode, resulting in low cycle efficiency. When the first solvent accounts for more than 40% of the electrolyte by mass, the electrolyte's low-temperature fluidity deteriorates, the freezing point increases, and the battery's discharge capability in environments below 0°C is severely affected.

[0065] Specifically, the mass percentage of the second solvent in the electrolyte is any one of the following values, or a range of any two values: 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%.

[0066] When the second solvent accounts for 5%–40% of the electrolyte by mass, chain-like fluorosulfonamide compounds effectively reduce electrolyte viscosity, improve low-temperature ionic conductivity, and enhance the passivation capability of aluminum current collectors. When the second solvent accounts for less than 5% of the electrolyte by mass, its effect on improving low-temperature performance is limited, and the battery capacity drops sharply in cold environments. When the second solvent accounts for more than 40% of the electrolyte by mass, its strong oxidizing properties may exacerbate side reactions at the positive electrode interface, and some fluorinated solvents are prone to react with trace amounts of water to generate HF, which corrodes the electrode materials.

[0067] Specifically, the first additive accounts for a range of any one or any two values ​​from the mass percentage of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5% in the electrolyte.

[0068] When the first additive accounts for 0.5%–5% of the electrolyte by mass, mannitol carbonate sulfate (CBS) can preferentially oxidize on the positive electrode surface to form a dense CEI film rich in sulfates and carbonates, effectively inhibiting electrolyte oxidation and transition metal dissolution. When the first additive accounts for less than 0.5% of the electrolyte by mass, the film formation is insufficient, and a continuous protective layer cannot be formed, resulting in accelerated degradation during high and low temperature cycling. When the first additive accounts for more than 5% of the electrolyte by mass, the accumulation of excessive CBS decomposition products leads to a sharp increase in interfacial impedance and deterioration of rate performance.

[0069] Specifically, the second additive accounts for a percentage of the electrolyte by mass of any one of the following values, or a range of any two values: 0.4%, 0.8%, 1.2%, 1.6%, 2%, 2.4%, 2.8%, 3.2%, 3.6%, 4%, 4.4%, 4.8%, 5.2%, 5.6%, 6%, 6.4%, 6.8%, 7.2%, 7.6%, 8%, 8.4%, 8.8%, 9.2%, 9.6%, or 10%.

[0070] When the second additive accounts for 0.4%–10% of the electrolyte by mass, succinate (SN) can not only form a highly stable SEI in conjunction with CBS at the negative electrode, but also complex trace amounts of water and metal ions, improving the purity of the system. When the second additive accounts for less than 0.4% of the electrolyte by mass, its functional effect is weak and it is difficult to effectively inhibit the continuous growth of SEI and the decomposition of electrolyte. When the second additive accounts for more than 10% of the electrolyte by mass, SN itself may undergo polymerization or reduction side reactions, producing gas or high-resistivity byproducts, causing battery swelling or a surge in internal resistance.

[0071] Specifically, the value of (A+C+D)*100 / X is any one value or a range of any two values ​​from 0.34, 0.50, 0.80, 1.20, 1.60, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, 8.00, 8.50, 9.00, or 9.24.

[0072] When the value of (A+C+D)*100 / X is 0.34–9.24, it indicates that the total amount of film-forming components (A+C+D) in the electrolyte is optimally matched with the cathode stabilizer (X), providing sufficient interfacial protection resources for the highly active cathode while avoiding excessively high impedance due to excessive film thickness. When the value of (A+C+D)*100 / X is less than 0.34, the interfacial film-forming capacity is far below the cathode stability requirements, and severe side reactions occur at the cathode-electrolyte interface under high temperature or high voltage, accelerating capacity decay. When the value of (A+C+D)*100 / X is greater than 9.24, there is an excess of film-forming components, forming a high-resistance passivation layer on the cathode surface, significantly increasing charge transfer impedance and impairing rate capability and low-temperature performance.

[0073] Specifically, the ratio (C+D)*10 / (B / 100+W+P) is any one value or a range of any two values ​​from 0.19, 0.30, 0.50, 0.70, 0.90, 1.10, 1.30, 1.50, 1.70, 1.90, 2.10, 2.30, or 2.48.

[0074] When the ratio of (C+D)*10 / (B / 100+W+P) is 0.19–2.48, the amount of functional additive (C+D) is precisely coordinated with the overall ion transport capacity of the battery (determined by solvent flowability B, negative electrode reaction area W, and membrane porosity P), achieving "on-demand film formation". When the ratio of (C+D)*10 / (B / 100+W+P) is less than 0.19, the additive is relatively insufficient and cannot form an effective interface film in a high-transport capacity system, resulting in poor cycle stability. When the ratio of (C+D)*10 / (B / 100+W+P) is greater than 2.48, the additive is excessive, causing ineffective deposition or side reactions in high-resistivity or low-transport systems, increasing internal resistance and generating gas.

[0075] Specifically, the ratio (C*0.01+H) / (B*0.01) is any one value or a range of any two values ​​from 2.67, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or 77.43.

[0076] When the ratio of (C*0.01+H) / (B*0.01) is 2.67–77.43, while introducing a highly active fluorinated solvent (B), the additive C and the ceramic coating H together construct a sufficiently strong protective barrier on the positive electrode side, balancing low-temperature kinetics and interface safety. When the ratio of (C*0.01+H) / (B*0.01) is less than 2.67, the corrosiveness of the fluorinated solvent is not effectively suppressed, the positive electrode interface continues to oxidize, and the high-temperature storage performance deteriorates. When the ratio of (C*0.01+H) / (B*0.01) is greater than 77.43, the protection is excessive, the interface film is too thick or the ceramic coating is too thick, resulting in obstructed ion transport and decreased rate performance.

[0077] Specifically, the P / Y ratio is any one value or a range of any two values ​​from 11.90, 15, 20, 25, 30, 35, 40, 45, 50, or 54.17.

[0078] When the P / Y ratio is 11.90–54.17, the membrane porosity (P) and the negative electrode compaction density (Y) achieve macroscopic charge transport balance, ensuring excellent ionic conductivity even at high volumetric energy density. When the P / Y ratio is less than 11.90, the negative electrode compaction is too high while the membrane porosity is insufficient, resulting in a prominent ion transport bottleneck, especially severe polarization during fast charging or at low temperatures. When the P / Y ratio is greater than 54.17, although there are sufficient ion channels, the negative electrode compaction density is too low, resulting in excessive sacrifice of volumetric energy density, and the electron conduction network is loose, affecting the overall power output.

[0079] This invention effectively suppresses the release of lattice oxygen under high voltage or high temperature by doping / coating the positive electrode active material with lanthanum, thereby reducing the exothermic reaction activity at the thermal runaway initiation temperature. The first additive (mannitol carbonate sulfate) and the second additive (succinate) in the electrolyte form a dense and highly thermally stable CEI film and SEI film on the positive and negative electrode surfaces, respectively. The ceramic coating of the separator provides a physical barrier, increases the thermal shrinkage temperature of the separator, and prevents internal short circuits.

[0080] Equation 1: 0.34≤(A+C+D)*100 / X≤9.24 precisely matches the interfacial film-forming resources (A+C+D) with the cathode stability requirements (X), avoiding insufficient protection or excessively high film resistance;

[0081] Equation 2: 0.19≤(C+D)*10 / (B / 100+W+P)≤2.48 precisely matches the total amount of functional additives (C+D) with the ion transport channels (B+W+P) to avoid excessive additives leading to interface passivation or insufficient additives leading to side reactions.

[0082] Equation 3: 2.67≤(C*0.01+H) / (B*0.01)≤77.43 ensures that while using fluorosulfonamide solvents, a sufficiently strong positive electrode side protection is constructed through mannitol carbonate sulfate and ceramic coating to effectively suppress electrolyte decomposition and gas generation and heat release at high temperatures.

[0083] Equation 4: 11.90≤P / Y≤54.17 Coordinating the ion channel (P) of the membrane with the negative electrode compaction density (Y), at high energy density (Y≥1g / cm³). 3 Under the premise of maintaining sufficient pore connectivity, it avoids ion diffusion being hindered due to excessive compaction, thus enabling it to have excellent low-temperature discharge performance.

[0084] CBS and SN synergistically form a compound rich in inorganic components (such as LiF, Li) at high temperatures. x SO y The stable CEI / SEI film effectively blocks continuous oxidation of the electrolyte and dissolution of transition metals. Lanthanum doping further inhibits the degradation of the positive electrode structure, reduces the dissolution of metal ions such as Mn / Ni / Co, and prevents them from migrating to the negative electrode and damaging the SEI. The electrolyte components are designed for anti-aging. Although the fluorinated solvent is easily oxidized, the ratio of its amount (B) to the protective strength (C+H) is constrained by Equation 3 to ensure that it does not undergo severe decomposition during long-term cycling at high temperatures.

[0085] This invention introduces specific material systems into the four core components of the positive electrode, negative electrode, separator, and electrolyte, and constructs a closed-loop collaborative design mechanism by combining four key parameter relationships (Equations 1–4), thereby achieving significant improvements in battery performance in terms of thermal shock safety, low-temperature discharge performance, and high-temperature cycle stability.

[0086] In a preferred embodiment, the values ​​A, B, C, D, X, W, Y, H, and P satisfy the following condition:

[0087] Equation 5: 0.56 ≤ (A+C+D)*100 / X ≤ 4.75;

[0088] Equation 6: 0.29 ≤ (C+D)*10 / (B / 100+W+P) ≤ 2.39;

[0089] Equation 7: 3.47≤(C*0.01+H) / (B*0.01)≤40.40;

[0090] Equation 8: 12.50≤P / Y≤45.00.

[0091] Specifically, when the battery satisfies Equations 5, 6, 7, and 8, the synergistic effect of each component is better, which can significantly improve the battery's thermal shock safety performance, low-temperature cycle performance, and high-temperature cycle performance.

[0092] In a preferred embodiment, the value of A ranges from 10 to 30; the value of B ranges from 10 to 30; the value of C ranges from 1 to 3; the value of D ranges from 1.2 to 6; the value of H ranges from 1.5 to 3; the value of P ranges from 30 to 60; the value of X ranges from 1000 to 2000; the value of W ranges from 4 to 20; and the value of Y ranges from 1.4 to 2.

[0093] This preferred embodiment, by tightening the windows of each component, ensures that all four relationships operate in the sub-regions with optimal performance, which can significantly improve the battery's thermal shock safety performance, low-temperature cycle performance, and high-temperature cycle performance.

[0094] In one embodiment, the cyclic carbonate compound includes one or more of ethylene carbonate and propylene carbonate.

[0095] The above-mentioned solvents are beneficial to the dissociation of lithium salts and can participate in the formation of a stable SEI film rich in lithium carbonate on the negative electrode surface.

[0096] In one embodiment, the chain-like fluorosulfonamide compound includes one or more of dimethylaminosulfonyl fluoride, 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, and N,N-diethylaminosulfonyl fluoride.

[0097] Specifically, the chain-like fluorosulfonamide compounds selected in this invention contain strongly electron-withdrawing sulfonamide groups (-SO2-NR2) and fluorine atoms in their molecules, which endow the compounds with high oxidation stability and low viscosity and low melting point, significantly improving the low-temperature fluidity of the electrolyte; moreover, the fluorinated structure helps to form an AlF3 passivation layer on the surface of the aluminum current collector, inhibiting aluminum corrosion; in synergy with additives such as CBS and SN, it can promote the formation of a highly ion-conducting interface film containing components such as LiF and R-SO2-Li.

[0098] In some embodiments, the electrolyte further includes a lithium salt, which includes one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium difluorophosphate, lithium bis(oxalate)borate, lithium difluorooxalateborate, lithium tetrafluoroborate, and lithium difluorodi(oxalate)borate. Using the above-mentioned lithium salt has the effects of providing a stable lithium ion source, promoting the formation of a dense SEI film, and improving the ionic conductivity and thermal stability of the electrolyte.

[0099] In some embodiments, the electrolyte further includes a base solvent, which includes one or more of ethylene carbonate, propylene carbonate, butene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl acetate, ethyl acetate, propyl acetate, propyl propionate, γ-butyrolactone, 1,3-dioxolane, and ethylene glycol dimethyl ether.

[0100] Specifically, the above-mentioned basic solvents are selected mainly to dissolve the first solvent, the second solvent, the first additive, the second additive, and the lithium salt.

[0101] It should be noted that this application does not impose any particular limitation on the preparation method of the electrolyte. Those skilled in the art can prepare the electrolyte using conventional technical means, such as mixing the raw materials evenly according to the specified ratio.

[0102] In one embodiment, the positive electrode active material further includes a transition metal lithium oxide doped with and / or coated with lanthanum.

[0103] Using transition metal lithium oxides doped with and / or coated with lanthanum as the positive electrode active material can improve the thermal stability of the crystal structure, suppress oxygen evolution, suppress transition metal dissolution, extend cycle life, optimize interface kinetics, reduce impedance growth, and synergistically construct a high-strength CEI film with electrolyte additives.

[0104] In one embodiment, the chemical formula of the transition metal lithium oxide is Li. 1+x Ni y Co z M (1-y-z) O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1;

[0105] M is selected from one or more of Mg, Zn, Ga, Ba, Al, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

[0106] By introducing lanthanum into transition metal lithium oxide (doping and / or coating), this invention improves cathode performance from three dimensions: bulk structure stability, surface interface protection, and ion transport optimization. It not only solves the inherent thermal safety and cycle degradation problems of high-nickel / high-voltage systems, but also forms a synergistic system with fluorosulfonamide solvents, CBS / SN additives, and ceramic separators in the electrolyte. Ultimately, it achieves a breakthrough in the comprehensive performance of batteries with high energy density, high safety, wide temperature range adaptability, and long life.

[0107] In some embodiments, the positive electrode active material layer further includes a positive electrode conductive agent and a positive electrode binder.

[0108] In some embodiments, the type of positive conductive agent mentioned in this invention is not limited, and any known conductive agent can be used.

[0109] In some embodiments, the positive electrode conductive agent mentioned in this invention includes at least one of carbon materials such as natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene.

[0110] In one embodiment, the type of positive electrode binder mentioned in this invention is not limited, and any known positive electrode binder can be used.

[0111] In some embodiments, the positive electrode binder includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose.

[0112] In some embodiments, the type of positive electrode current collector is not particularly limited, and it can be any known material suitable for use as a positive electrode current collector. In one embodiment, the positive electrode current collector includes metallic materials such as lanthanum, stainless steel, lanthanum plating, titanium, and tantalum, as well as carbon materials such as carbon cloth and carbon paper. In one embodiment, the positive electrode current collector is a metallic material.

[0113] In one embodiment, the ceramic coating comprises one or more of alumina, aluminum hydroxide, boehmite, titanium dioxide, and silicon dioxide.

[0114] Coating the base membrane with a ceramic coating not only endows the separator with excellent thermal shutdown resistance and electrolyte affinity, but also forms a deep synergy with the overall design of this invention (such as lanthanum-doped cathode, fluorosulfonamide electrolyte, CBS / SN additive), jointly supporting breakthroughs in key performance dimensions such as high safety, wide temperature range, and long cycle life of the battery, and providing reliable protection for the extreme environment application of high energy density lithium-ion batteries.

[0115] In one embodiment, the separator is located between the positive electrode and the negative electrode.

[0116] This application does not impose any particular restrictions on the material and shape of the diaphragm, as long as it does not significantly impair the effectiveness of this application.

[0117] In some embodiments, the diaphragm includes a porous sheet-like or non-woven material with excellent liquid retention properties. The diaphragm includes resin or glass fiber diaphragm materials, including but not limited to polyolefins, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, etc.

[0118] In one embodiment, the negative electrode active material layer includes a negative electrode active material, which includes one or more of graphite, silicon-carbon composite material, or lithium metal material.

[0119] The optimal design of the negative electrode active material is synergistic with the positive electrode and functionalized electrolyte to maximize the overall performance of the battery.

[0120] In some embodiments, there are no particular limitations 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, lanthanum foil, stainless steel foil, titanium foil, foamed lanthanum, foamed copper, or composite current collector, etc.

[0121] In some preferred embodiments, the negative current collector comprises copper foil.

[0122] In some embodiments, the negative electrode active material layer is disposed on at least one side surface of the negative electrode current collector, and the negative electrode active material layer further includes a negative electrode conductive agent, a negative electrode binder, a negative electrode thickener, and a negative electrode solvent.

[0123] The negative electrode conductive agent includes at least one of the following carbon materials: natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene.

[0124] Negative electrode binders include styrene-butadiene latex, etc.

[0125] Negative electrode thickeners include CMC, etc.

[0126] Negative electrode solvents include deionized water, etc.

[0127] In some embodiments, the lithium-ion battery may include an outer packaging that can be used to encapsulate the electrode assembly and electrolyte described above.

[0128] In one embodiment, another aspect of the present invention provides an electrical device including the battery described above.

[0129] Specifically, the aforementioned electrical 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., but are not limited to these.

[0130] The present invention will be further illustrated by the following examples.

[0131] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described in detail below with reference to embodiments. However, it should be understood that the embodiments of this invention are merely for illustrative purposes and not for limiting the invention, and the embodiments are not limited to those given in the specification. Materials not specified in the embodiments were prepared under conventional conditions or according to the conditions recommended by the material supplier.

[0132] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0133] In the following embodiments, the reagents, materials and instruments used, unless otherwise specified, are commercially available or can be obtained through synthesis methods known in the art.

[0134] Table 1. Design of battery components for Examples 1-53 and Comparative Examples 1-33;

[0135]

[0136] Continued from Table 1

[0137]

[0138] Continued from Table 1

[0139]

[0140] Continued from Table 1

[0141]

[0142] Table 2. Design of battery components for Examples 3, 54-60 and Comparative Examples 34-38;

[0143]

[0144] Example 1

[0145] This embodiment illustrates the lithium-ion battery disclosed in this invention, and includes the following operational steps:

[0146] Preparation of positive electrode

[0147] The positive electrode active material (LiCoO2 doped with lanthanum), the positive electrode conductive agent acetylene black (SuperP), and the polyvinylidene fluoride (PVDF) binder are mixed evenly at a mass ratio of 96.5:2.0:1.5, and then evenly dispersed with 1-methyl-2-pyrrolidone (NMP) to form a uniform positive electrode slurry. The mixed slurry is coated on both sides of the aluminum foil current collector, and then baked, rolled, and cut into sheets to obtain the positive electrode sheet.

[0148] The specific values ​​of lanthanum content in the positive electrode active material are shown in Table 1.

[0149] Preparation of negative electrode

[0150] Artificial graphite (anode active material), acetylene black (Super P) (anode conductive agent), sodium carboxymethyl cellulose (CMC) (thickener), and styrene-butadiene rubber (SBR) (anode binder) were mixed uniformly at a mass ratio of 96:1.5:1.0:1.5 and then dispersed evenly with deionized water to form a homogeneous anode slurry. The slurry was coated onto both sides of a copper foil current collector, then baked and rolled to a predetermined compaction density. After cutting, the anode sheet was obtained. The specific surface area (W) and compaction density (Y) of the anode active material are shown in Table 1.

[0151] Preparation of diaphragm

[0152] An alumina ceramic slurry was coated on one side of a porous polyethylene (PE) base membrane (facing the positive electrode in the battery) using a coating machine, and the membrane with a ceramic coating was obtained after drying. The specific values ​​of ceramic layer thickness (H) and base membrane porosity (P) are shown in Table 1.

[0153] Preparation of electrolyte

[0154] a. In an argon-filled glove box, propyl propionate (PP) and diethyl carbonate (DEC) are mixed at a mass ratio of 3:7 as the base solvent, and 1M LiPF6 lithium salt is added and mixed evenly.

[0155] b. Add the first solvent (cyclic carbonate), the second solvent (fluorosulfonamide solvent), the first additive mannitol carbonate sulfate (CBS), and the second additive succinate (SN) to the solution obtained in step a (the types and amounts of each component are shown in Table 1 and Table 2), stir evenly, and the electrolyte is obtained.

[0156] Manufacturing of lithium-ion batteries

[0157] The prepared positive electrode sheet, separator (ceramic coating facing the positive electrode), and negative electrode sheet are stacked in sequence, and then wound and welded to obtain a bare cell. The bare cell is placed in an aluminum-plastic film, and the above-mentioned electrolyte is injected. After encapsulation, standing, formation, and shaping, a lithium-ion soft-pack battery is obtained.

[0158] Examples 2-60

[0159] Examples 2-53 illustrate the lithium-ion battery disclosed in this invention, including most of the operations in Example 1, except that:

[0160] In Examples 2-53, the first solvent mass percentage A / %, and the second solvent mass percentage B / %.

[0161] The mass percentage of the first additive is C / %, the mass percentage of the second additive is D / %, the content of lanthanum in the positive electrode active material is X / %, and the specific surface area of ​​the negative electrode active material layer is W / m². 2 / g, the compaction density of the negative electrode active material layer is Y g / cm³ 3 The thickness of the ceramic coating is H / μm, the porosity of the base film is P / %, and the values ​​of (A+C+D)*100 / X, (C+D)*10 / (B / 100+W+P), (C*0.01+H) / (B*0.01), and P / Y are all referenced in Table 1.

[0162] Examples 54-60 illustrate the lithium-ion battery disclosed in this invention, including most of the operations in Example 3, except that:

[0163] In Examples 54-60, the types of the first solvent, the second solvent, the first additive, the second additive, and the ceramic layer are all as described in Table 2.

[0164] Comparative Examples 1-38

[0165] Comparative Examples 1-33 include most of the operations in Example 1, except that:

[0166] The mass percentages of the first solvent (A / %), the second solvent (B / %), the first additive (C / %), the second additive (D / %), and the lanthanum content (X / %) in the positive electrode active material in Comparative Examples 1-33 are shown. The specific surface area of ​​the negative electrode active material layer is W m². 2 / g, the compaction density of the negative electrode active material layer is Y g / cm³ 3 The thickness of the ceramic coating is H / μm, the porosity of the base film is P / %, and the values ​​of (A+C+D)*100 / X, (C+D)*10 / (B / 100+W+P), (C*0.01+H) / (B*0.01), and P / Y are all referenced in Table 1.

[0167] Comparative Examples 34-38 include most of the operations in Example 3, except that:

[0168] The types of the first solvent, the second solvent, the first additive, the second additive, and the ceramic layer in Comparative Examples 34-38 are all referenced in Table 2.

[0169] The method for testing the lanthanum content in the positive electrode active material layer is as follows:

[0170] After the battery was manufactured and discharged, it was disassembled. 5 mg of the positive electrode active material layer was taken and 3 mL of concentrated sulfuric acid and 3 mL of concentrated nitric acid were added in sequence. The mixture was heated to 180°C until the solution was clear and transparent. After cooling, water was added to make up to 50 mL. The sample was sent for testing, and the content of lanthanum was determined using an ICP (Inductively Coupled Plasma Emission Spectrometer).

[0171] Performance testing

[0172] The following performance tests were performed on Examples 1-60 and Comparative Examples 1-38 prepared above:

[0173] Thermal shock test

[0174] The lithium-ion batteries prepared in the above embodiments and comparative examples were charged at 25°C at a rate of 1C to the cutoff voltage and a cutoff current of 0.025C. They were then transferred to an oven and heated to 150°C at a rate of 5°C / min and kept constant for 60 minutes. The batteries were considered to have passed the test if they did not catch fire or explode. The number of test cells was 20.

[0175] 0℃ Cyclic Performance Test

[0176] The lithium-ion batteries prepared in the above embodiments and comparative examples were 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 X2 = Y2 / Y1 of the Nth cycle. The number of cycles of the lithium-ion battery when the cycle capacity retention rate X2 was 80% was recorded.

[0177] 45℃ Cyclic Performance Test

[0178] The lithium-ion batteries prepared in the above embodiments and comparative examples were 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.

[0179] The test results are shown in Table 3.

[0180] Table 3 Battery performance test results of Examples 1-60 and Comparative Examples 1-38

[0181]

[0182] Continued from Table 3

[0183]

[0184] Continued from Table 3

[0185]

[0186] Continued from Table 3

[0187]

[0188] Comparing Example 3 and Comparative Example 1, it can be seen that when the electrolyte uses the first solvent, the second solvent, the first additive, and the second additive, the separator has a ceramic coating facing the positive electrode side, the positive electrode active material contains lanthanum, the negative electrode active material has a specific surface area and compaction density, and the overall system satisfies the four defined synergistic relationships, the cycle stability of the battery at 0°C and 45°C is significantly improved. The number of cycles at 0°C with a capacity retention of 80% reaches 605 cycles, and at 45°C it reaches 609 cycles. At the same time, the number of cells that pass the thermal shock test is 18 (out of 20), indicating that the system has both excellent cycle durability and high thermal safety over a wide temperature range.

[0189] When the electrolyte lacks the first solvent, second solvent, first additive, and second additive (using only a conventional carbonate-based system), the separator lacks a ceramic coating facing the positive electrode, lanthanum is not introduced into the positive electrode active material, and the four defined synergistic relationships cannot be satisfied as a whole, the number of cycles at 0℃ and 45℃ to achieve 80% capacity retention drops sharply to 235 and 216 cycles, respectively, with zero thermal shocks. This is because the lack of multi-component synergistic regulation makes the positive electrode structure prone to phase transitions and transition metal dissolution during high and low temperature cycling. The electrolyte continuously decomposes at the high / low temperature interface, the SEI / CEI film becomes unstable and its impedance rises rapidly. At the same time, the thermal shrinkage of the separator triggers the risk of internal short circuits, ultimately resulting in a severe reduction in battery cycle life and a sharp deterioration in thermal stability.

[0190] Comparing Examples 1-5, Comparative Example 2, and Comparative Examples 8-9, it can be seen that when the first solvent accounts for 5%–40% of the electrolyte by mass, the number of cycles at 0°C is 567–605, the number of cycles at 45°C is 563–609, and the number of particles passing thermal shock is 16–19, indicating that the battery exhibits good overall performance over a wide temperature range. When the first solvent accounts for less than 5% of the electrolyte by mass, the number of cycles at 0°C and 45°C drops to 278 and 277, respectively, and the number of particles passing thermal shock is only 5, indicating insufficient lithium salt dissociation, low ionic conductivity, and difficulty in forming a negative electrode. The lack of an effective SEI results in low cycle efficiency. When the first solvent accounts for more than 40% of the electrolyte by mass, the cycle count at 0°C drops to 291 cycles, and at 45°C it is 270 cycles, with zero thermal shock particles passing through. This is because the increased solvent viscosity, excessively thick SEI, and high organic content hinder low-temperature ion transport and exacerbate high-temperature side reactions. When the first solvent is absent from the electrolyte, the cycle counts at 0°C and 45°C are only 267 and 268 cycles, respectively, with only 7 thermal shock particles passing through. This indicates that the lack of cyclic carbonates prevents the formation of an effective SEI matrix, resulting in significantly poor cycle and safety performance.

[0191] Comparing Examples 3, 6-10, 3, and 10-11, it can be seen that when the second solvent accounts for 5%–40% of the electrolyte by mass, the number of cycles at 0°C is 567–622, the number of cycles at 45°C is 563–621, and the number of particles passing through the thermal shock is 14–20, indicating balanced high and low temperature performance. When the second solvent accounts for less than 5% of the electrolyte by mass, the number of cycles at 0°C is 278, the number of cycles at 45°C is 256, and the number of particles passing through the thermal shock is 5. Due to insufficient fluorosulfonamide, the high-temperature performance is poor. The EI protection is weak, and the positive electrode corrosion is severe. When the mass percentage of the second solvent in the electrolyte is greater than 40%, the number of cycles at 0°C increases to 418 cycles, but the number of cycles at 45°C drops sharply to 212 cycles, and the number of thermal shock particles passing through is 0. This is because the excessive fluorinated solvent decomposes to produce HF, which corrodes the current collector and damages the interface. When there is no second solvent in the electrolyte (such as in Comparative Example 3), the number of cycles at 0°C and 45°C are 250 cycles and 302 cycles, respectively, and the number of thermal shock particles passing through is 7. This indicates that the lack of fluorinated solvent leads to insufficient low-temperature ionic conductivity and poor high-temperature oxidation stability.

[0192] Comparing Examples 3, 11-15, 4, and 12-13, it can be seen that when the first additive accounts for 0.5%–5% of the electrolyte by mass, the number of cycles at 0°C is 531–621, the number of cycles at 45°C is 561–609, the number of particles passing through the thermal shock is 15–20, and the positive electrode interface is stable. When the content of the first additive is less than 0.5%, the number of cycles at 0°C and 45°C decreases to 211 and 239, respectively, and the number of particles passing through the thermal shock is 5. Insufficient film formation prevents the formation of a continuous protective layer, leading to accelerated degradation during high and low temperature cycling. When the content of the first additive is greater than 5%, the number of cycles at 0℃ is 211, and at 45℃ it is 239, with only 12 particles passing through the thermal shock test. This is due to the excessive thickness of the CEI causing a sharp increase in interfacial impedance. When the first additive is absent in the electrolyte, the number of cycles at 0℃ and 45℃ are 265 and 273, respectively, with only 5 particles passing through the thermal shock test. This indicates that the lack of CBS-type additives makes it impossible to construct a highly stable CEI.

[0193] Comparing Examples 3, 16-20, 5, and 14-15, it can be seen that when the second additive accounts for 0.4%–10% of the electrolyte by mass, the number of cycles at 0°C is 561–605, the number of cycles at 45°C is 552–609, and the number of particles passing through thermal shock is 16–19. When the content of the second additive is less than 0.4%, the number of cycles at 0°C and 45°C decreases to 265 and 288, respectively, and the number of particles passing through thermal shock is 5. Insufficient interface modification resulted in poor SEI / CEI toughness. When the content of the second additive was greater than 10%, the number of cycles at 0℃ was 211, and at 45℃ it was 206, with 7 particles passing through the thermal shock test, indicating that excessive SN decomposition produced high-resistance nitrogen-containing polymers. When the second additive was absent in the electrolyte, the number of cycles at 0℃ and 45℃ were 248 and 276, respectively, with 5 particles passing through the thermal shock test, indicating that the lack of succinate led to insufficient interfacial ionic conductivity and structural stability.

[0194] Comparing Examples 3, 21-25, 6, and 16-17, it can be seen that when the ceramic coating thickness is 0.5–5 μm, the number of cycles at 0°C is 531–622, the number of cycles at 45°C is 532–609, and the number of particles passing through the thermal shock barrier is 15–20. When the ceramic coating thickness is less than 0.5 μm, the number of cycles at 0°C is 255, the number of cycles at 45°C is 279, and the number of particles passing through the thermal shock barrier is 6. Due to insufficient physical barrier, it is not possible to effectively prevent the diaphragm from being damaged at high temperatures. Shrinkage and deformation result in insufficient protection against thermal runaway. When the ceramic coating thickness is greater than 5 μm, the cycle count at 0℃ and 45℃ drops to 156 and 189 cycles, respectively, with only 12 particles passing through the thermal shock test. Excessive coating thickness hinders ion transport. When the base film surface is not coated with a ceramic coating, the cycle count at 0℃ and 45℃ is 262 and 277 cycles, respectively, with only 5 particles passing through the thermal shock test. Excessive coating thickness will block the original pores of the separator, reduce pore connectivity, increase ion transport resistance, and lead to an increase in battery internal resistance and a decrease in rate performance.

[0195] Comparing Examples 3, 26-30, and 18-19, it can be seen that when the porosity of the base film is 20-70%, the number of cycles at 0°C is 531-605, the number of cycles at 45°C is 548-609, and the number of particles passing through the thermal shock is 12-20. When the porosity of the base film is less than 20%, the number of cycles at 0°C is 267, the number of cycles at 45°C is 284, and the number of particles passing through the thermal shock is 4. Due to the limited ion transport channels, severe concentration polarization is likely to occur at low temperatures or high current densities. When the porosity of the base film is greater than 70%, the number of cycles at 0°C and 45°C decreases to 231 and 225, respectively, and the number of particles passing through the thermal shock is 3. Due to the decrease in mechanical strength, the thermal shock is likely to cause a short circuit.

[0196] Comparing Examples 3, 31-35, 7, and 20-21, it can be seen that when the mass content of lanthanum in the positive electrode active material layer is 400ppm–2500ppm, the cycle count at 0℃ is 553–605 cycles, the cycle count at 45℃ is 569–609 cycles, and the number of particles passing through thermal shock is 16–19. When the lanthanum content is less than 400ppm, the cycle count at 0℃ is 235 cycles, the cycle count at 45℃ is 267 cycles, and the number of particles passing through thermal shock is 4, leading to a decrease in thermal stability and cycle life. When the lanthanum content is greater than 2500ppm, the cycle count at 0℃ and... The cycle life at 45℃ decreased to 221 and 243 cycles respectively, with 10 particles passing through thermal shock, due to excessive doping blocking lithium-ion channels. When the cathode does not contain lanthanum, the cycle life at 0℃ and 45℃ is 256 and 271 cycles respectively, with 3 particles passing through thermal shock. Due to the lack of lanthanum's stabilizing effect on the lattice structure of the cathode active material and its protective effect on the electrode / electrolyte interface, lithium-ion migration is hindered at low temperatures and transition metal dissolution is intensified at high temperatures. At the same time, the material is prone to microcrack propagation and local exothermic reactions during thermal shock, thus significantly reducing cycle life and safety.

[0197] Comparing Examples 3, 36-40, and 22-23, it can be seen that when the specific surface area of ​​the negative electrode active material layer is 1–30 m², 2 At / g, the number of cycles at 0℃ is 531–622, and at 45℃ it is 542–609, with 15–19 particles passing through the thermal shock; when the specific surface area is less than 1m² 2 At / g, the cycle count at 0℃ is 211 cycles, and at 45℃ it is 209 cycles. The number of particles passing through the thermal shock is 1. Due to low reactivity, the low-temperature performance deteriorates significantly. When the specific surface area is greater than 30m², 2 At / g, the number of cycles at 0℃ is 251, the number of cycles at 45℃ is 224, and the number of thermal shock particles passing through is 0. Due to excessive SEI growth, active lithium is consumed, which exacerbates the cycling risk.

[0198] Comparing Examples 3, 41-45, and 24-25, it can be seen that when the compaction density of the negative electrode active material layer is 1–2.2 g / cm³, 3 At 0℃, the number of cycles is 578–623, and at 45℃, the number of cycles is 562–609, with 16–19 particles passing through the thermal shock. When the compaction density is less than 1 g / cm³, the number of cycles is 16–19. 3 At 0℃, the cycle count was 278 cycles, and at 45℃, it was 234 cycles. Only one particle passed through the thermal shock test. Due to the loose electrode structure, the contact resistance was high. When the compaction density was greater than 2.2 g / cm³... 3 At 0℃, the cycle count was 223 cycles, and at 45℃, the cycle count was 261 cycles. The number of particles passing through the thermal shock was 2. Due to the blockage of the ion diffusion path, the polarization was intensified.

[0199] Comparing Examples 1, 3, 31, 46-47, and 26-27, it can be seen that when the value of (A+C+D)*100 / X is 0.34–9.24, the number of cycles at 0℃ is 524–605, the number of cycles at 45℃ is 526–609, and the number of particles passing through thermal shock is 16–19. When the value is less than 0.34, the number of cycles at 0℃ is 442, the number of cycles at 45℃ is 434, and the number of particles passing through thermal shock is 12, indicating insufficient film-forming resources and weak interface protection. When the value is greater than 9.24, the number of cycles at 0℃ and 45℃ are 445 and 432 respectively, and the number of particles passing through thermal shock is 10, indicating excessively thick interface film and high high-temperature resistance.

[0200] Comparing Examples 3, 46-49, and 28-29, it can be seen that when the ratio of (C+D)*10 / (B / 100+W+P) is 0.19–2.48, the number of cycles at 0°C is 524–658, the number of cycles at 45°C is 511–609, and the number of particles passing through thermal shock is 12–18. When the ratio is less than 0.19, the number of cycles at 0°C is 576, the number of cycles at 45°C is 417, and the number of particles passing through thermal shock is 12. Due to the relatively insufficient additive concentration, an effective interface film cannot be formed in the high transport capacity system, resulting in poor cycle stability. When the ratio is greater than 2.48, the number of cycles at 0°C is 426, the number of cycles at 45°C is 441, and the number of particles passing through thermal shock is 12. The additive is excessive, which causes ineffective deposition or side reactions in high-resistivity or low-transport systems, increasing internal resistance and generating gas.

[0201] Comparing Examples 3, 6, 21, 50-51, and 30-31, it can be seen that when the ratio of (C*0.01+H) / (B*0.01) is 2.67–77.43, the number of cycles at 0℃ is 506–623, the number of cycles at 45℃ is 509–621, and the number of particles passing through thermal shock is 14–20. When the ratio is less than 2.67, the number of cycles at 0℃ is 541, the number of cycles at 45℃ is 421, and the number of particles passing through thermal shock is 9. The corrosiveness of the fluorinated solvent is not effectively suppressed, the positive electrode interface continues to oxidize, and the high-temperature storage performance deteriorates. When the ratio is greater than 77.43, the number of cycles at 0℃ is 424, the number of cycles at 45℃ is 415, and the number of particles passing through thermal shock is 12. Excessive thickness of the interface film or excessively thick ceramic coating leads to obstructed ion transport and a decrease in rate performance.

[0202] Comparing Examples 3, 26, 41, 52-53, and 32-33, it can be seen that when the P / Y ratio is 11.90–54.17, the number of cycles at 0℃ is 500–635, the number of cycles at 45℃ is 503–609, and the number of particles passing through thermal shock is 14–20. When the ratio is less than 11.90, the number of cycles at 0℃ is 418, the number of cycles at 45℃ is 418, and the number of particles passing through thermal shock is 2. The negative electrode compaction is too high and the membrane porosity is insufficient, resulting in a prominent bottleneck in ion transport, especially with severe polarization under fast charging or low temperature. When the ratio is greater than 54.17, the number of cycles at 0℃ is 563, the number of cycles at 45℃ is 409, and the number of particles passing through thermal shock is 11. The negative electrode compaction density is too low, the volumetric energy density is sacrificed too much, and the electron conduction network is loose, affecting the overall power output.

[0203] Comparing Examples 3, 54, and 34, it can be seen that when the first solvent is ethylene carbonate or propylene carbonate, the number of cycles at 0°C is 602-605, the number of cycles at 45°C is 607-609, and the number of particles passing the thermal shock is 18. When the first solvent is diethyl carbonate, the number of cycles at 0°C is 268, the number of cycles at 45°C is 269, and the number of particles passing the thermal shock is 4. Because an effective SEI cannot be formed on the negative electrode, the battery performance is significantly reduced.

[0204] Comparing Examples 3, 55-56, and Comparative Example 35, it can be seen that when the second solvent is dimethylaminosulfonyl fluoride, 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, or N,N-diethylaminosulfonyl fluoride, the cycle count at 0°C is 604–605 cycles, at 45°C it is 608–609 cycles, and the number of particles passing the thermal shock is 18. When the second solvent is fluoroethylene carbonate, the cycle count at 0°C is 261 cycles, at 45°C it is 237 cycles, and the number of particles passing the thermal shock is 3. Because it is easily oxidized and decomposed under high voltage, it cannot provide long-term interface protection, and the high-temperature cycle performance of the battery decreases.

[0205] Comparing Example 3 and Comparative Example 36, it can be seen that when the first additive is mannitol sulfate carbonate, the number of cycles at 0°C is 605, the number of cycles at 45°C is 609, and the number of particles passing the thermal shock is 18. When the first additive is 1,3-propanesulfonyl lactone, the number of cycles at 0°C is 245, the number of cycles at 45°C is 216, and the number of particles passing the thermal shock is 2. Because it is impossible to form a highly stable CEI with both polymer matrix and Li2SO4 crosslinking structure, the overall performance of the battery decreases.

[0206] Comparing Example 3 and Comparative Example 37, it can be seen that when the second additive is succinic anionylene, the number of cycles at 0°C is 605, the number of cycles at 45°C is 609, and the number of particles passing the thermal shock is 18. When the second additive is butyronitrile, the number of cycles at 0°C is 241, the number of cycles at 45°C is 231, and the number of particles passing the thermal shock is 4. Because its polymerization activity and complexing ability are weaker than that of succinic anionylene, it is not possible to effectively construct a high-toughness interface layer, and the high and low temperature performance and safety of the battery are reduced.

[0207] Comparing Examples 3, 57-60, and Comparative Example 38, it can be seen that when the ceramic coating is alumina, aluminum hydroxide, boehmite, silicon dioxide, or titanium dioxide, the number of cycles at 0°C is 603–606, the number of cycles at 45°C is 607–609, and the number of particles passing the thermal shock is 18. When the ceramic coating is lithium aluminum titanium phosphate (LATP), the number of particles passing the thermal shock is 4, and the number of cycles at 0°C and 45°C is 235 and 222, respectively. Because LATP may have interfacial side reactions or poor ion conductivity matching in the liquid electrolyte, the battery performance is not optimal. This indicates that not all ceramic materials are suitable for this system, and it is necessary to select an oxide that has both chemical inertness and thermal stability.

[0208] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A battery, characterized in that, include: A positive electrode sheet, comprising a positive current collector and a positive active material layer disposed on the positive current collector, wherein the positive active material layer comprises a positive active material, and the positive active material comprises a transition metal lithium oxide doped with and / or coated with lanthanum; the mass content of lanthanum in the positive active material layer is X ppm, wherein the value of X ranges from 400 to 2500. The negative electrode includes a negative current collector and a negative active material layer disposed on the negative current collector; the specific surface area of ​​the negative active material layer is W m². 2 / g, where W ranges from 1 to 30; the compaction density of the negative electrode active material layer is Y g / cm³. 3 The value of Y ranges from 1 to 2.2; A diaphragm, comprising a base membrane and a ceramic coating coated on the surface of the base membrane; the thickness of the ceramic coating is H μm, wherein the value of H ranges from 0.5 to 5; the porosity of the base membrane is P %, wherein the value of P ranges from 20 to 70; the ceramic coating comprises one or more of alumina, aluminum hydroxide, boehmite, titanium dioxide, and silicon dioxide. An electrolyte comprising a first solvent, a second solvent, a first additive, and a second additive; the first solvent comprises a cyclic carbonate compound, the second solvent comprises a chain-like fluorosulfonamide compound, the first additive comprises mannitol sulfate, and the second additive comprises succinate; the total mass of the electrolyte is denoted as 100%, the mass percentage of the first solvent in the electrolyte is denoted as A%, where A ranges from 5 to 40%; the mass percentage of the second solvent in the electrolyte is denoted as B%, where B ranges from 5 to 40%; the mass percentage of the first additive in the electrolyte is denoted as C%, where C ranges from 0.5 to 5%; and the mass percentage of the second additive in the electrolyte is denoted as D%, where D ranges from 0.4 to 10%. The cyclic carbonate compounds include one or more of ethylene carbonate and propylene carbonate; The chain-like fluorosulfonamide compounds include one or more of dimethylaminosulfonyl fluoride, 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, and N,N-diethylaminosulfonyl fluoride; The values ​​A, B, C, D, X, W, Y, H, and P satisfy the following condition: Equation 1: 0.34 ≤ (A+C+D)*100 / X ≤ 9.24; Equation 2: 0.19≤(C+D)*10 / (B / 100+W+P)≤2.48; Equation 3: 2.67≤(C*0.01+H) / (B*0.01)≤77.43; Equation 4: 11.90≤P / Y≤54.

17.

2. The battery according to claim 1, characterized in that, The values ​​A, B, C, D, X, W, Y, H, and P satisfy the following condition: Equation 5: 0.56 ≤ (A+C+D)*100 / X ≤ 4.75; Equation 6: 0.29 ≤ (C+D)*10 / (B / 100+W+P) ≤ 2.39; Equation 7: 3.47≤(C*0.01+H) / (B*0.01)≤40.40; Equation 8: 12.50≤P / Y≤45.

00.

3. The battery according to claim 1, characterized in that, The value range of A is 10-30; the value range of B is 10-30; the value range of C is 1-3; the value range of D is 1.2-6; the value range of H is 1.5-3; the value range of P is 30-60; the value range of X is 1000-2000; the value range of W is 4-20; and the value range of Y is 1.4-2.

4. The battery according to claim 1, characterized in that, The chemical formula of the transition metal lithium oxide is Li 1+ x Ni y Co z M (1-y-z) O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; M is selected from one or more of Mg, Zn, Ga, Ba, Al, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

5. The battery according to claim 1, characterized in that, The negative electrode active material layer includes a negative electrode active material, which includes one or more of graphite, silicon-carbon composite materials, or lithium metal materials.

6. An electrical device, characterized in that, Includes the battery as described in any one of claims 1 to 5.

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