Battery and electrical device

Abstract

A battery comprising an electrolyte solution and a positive electrode foil, wherein the positive electrode foil has a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, wherein the positive active material layer contains a positive active material, wherein the positive active material comprises lithium iron phosphate, characterized in that the electrolyte solution contains tris-(dimethylvinylsilyl)phosphate; and the battery satisfies the following relationship: 0.3 < a × b × c < 124, where a is a mass fraction of tris-(dimethylvinylsilyl)phosphate in the electrolyte solution; b is the contact angle between the positive active material layer and the solution in units of degrees (°), wherein the solution consists of ethylene carbonate, ethyl methyl carbonate and lithium hexafluorophosphate, wherein the mass ratio of ethylene carbonate to ethyl methyl carbonate is 3:7 and the concentration of lithium hexafluorophosphate in the solution is 1 mol / l; and c is the powder resistance of the positive active material layer, in units of Ω·cm.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of battery technology, in particular to a battery and an electrical device. STATE OF THE ART

[0002] Lithium iron phosphate batteries have advantages such as high operating voltage, high energy density, a good safety profile, a low self-discharge rate, and the absence of a memory effect. However, lithium iron phosphate batteries exhibit significant internal gas generation. The addition of phosphate ester additives to the electrolyte solution can inhibit gas generation but increases the battery's direct current resistance (DCR), especially in pre-lithiation systems (i.e., positive electrode foils containing pre-lithiation additives). SUMMARY

[0003] The object of the present invention is to overcome the above-mentioned deficiencies of the prior art by providing a battery and an electrical device to enable lithium iron phosphate batteries to achieve both low gas generation and low DCR.

[0004] To achieve the above object, the present invention provides, in a first aspect, a battery including an electrolytic solution and a positive electrode foil, the positive electrode foil having a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, the positive active material layer containing a positive active material, the positive active material including lithium iron phosphate, and the electrolytic solution containing tris-(dimethylvinylsilyl)phosphate; and the battery satisfies the following relationship: 0.3 < a × b × c < 124, where a is the mass fraction of tris-(dimethylvinylsilyl)phosphate in the electrolytic solution;b is the contact angle between the positive active material layer and the solution in units of degrees (°), the solution consisting of ethylene carbonate, ethyl methyl carbonate, and lithium hexafluorophosphate, the mass ratio of ethylene carbonate to ethyl methyl carbonate being 3:7 and the concentration of lithium hexafluorophosphate in the solution being 1 mol / L; c is the powder resistance of the positive active material layer, in units of Ω cm.;

[0005] In a second aspect, the present invention provides an electrical device comprising the battery.

[0006] Compared with the prior art, the present invention has the following advantageous effects: by selectively adjusting the mass fraction of tris-(dimethylvinylsilyl)phosphate in the electrolytic solution, the contact angle between the positive active material layer and the solution, and the powder resistance of the positive active material layer to satisfy a specific relationship, the battery has fewer side reactions and less gas generation during cycling, and the positive electrode foil has high conductivity for ions and electrons, thereby achieving both low gas generation and a low DCR. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0007] To clarify the purpose, technical solutions, and advantages of the embodiments of the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. It is understood that the described embodiments represent only a portion of the embodiments of the present invention and not all embodiments. Starting from the embodiments of the present invention, all other embodiments that a person skilled in the art would obtain without inventive step fall within the scope of the present invention.

[0008] In the present invention, technical features described in an open manner include both closed technical solutions composed of the enumerated features and open technical solutions including the enumerated features.

[0009] Regarding numerical ranges, in the present invention, unless otherwise stated, the above numerical ranges are to be considered continuous, including the lowest and highest values ​​of the range as well as all values ​​between these lowest and highest values. When the range refers to integers, it further includes any integer between the lowest and highest values ​​of the range. Furthermore, when multiple ranges are specified to describe features or properties, these ranges may be combined. In other words, all ranges specified herein, unless otherwise stated, are to be understood as covering all subranges contained therein.

[0010] The present invention is not particularly limited with regard to specific dispersion and stirring treatment methods.

[0011] The reagents or instruments used in the present invention without mentioning the manufacturer are conventional products that are commercially available. battery

[0012] The present invention provides a battery including an electrolyte solution and a positive electrode foil, wherein the positive electrode foil has a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, wherein the positive active material layer contains a positive active material, the positive active material includes lithium iron phosphate, and the electrolyte solution contains tris-(dimethylvinylsilyl) phosphate (DMVSP); and the battery satisfies the following relationship: 0.3 < a × b × c < 124, where a is the mass fraction of tris-(dimethylvinylsilyl) phosphate in the electrolyte solution;b is the contact angle between the positive active material layer and the solution in units of degrees (°), the solution consisting of ethylene carbonate, ethyl methyl carbonate, and lithium hexafluorophosphate, the mass ratio of ethylene carbonate to ethyl methyl carbonate being 3:7 and the concentration of lithium hexafluorophosphate in the solution being 1 mol / L; c is the powder resistance of the positive active material layer, in units of Ω cm.;

[0013] By appropriately controlling the mass fraction of DMVSP in the electrolyte solution, the contact angle between the positive active material layer and the solution, and the powder resistance of the positive active material layer, the battery has fewer side reactions and lower gas generation during cycling, and the positive electrode foil has high conductivity for ions and electrons, thereby achieving both low gas generation and low DCR.

[0014] The mass fraction (a) of DMVSP in the electrolyte solution influences gas generation and the battery's DCR value. Increasing the mass fraction (a) of DMVSP in the electrolyte solution is beneficial for reducing gas generation in the battery, but leads to an increase in the battery's DCR value. The mass fraction (a) of DMVSP in the electrolyte solution can be adjusted by adjusting the ratio of electrolyte solution to DMVSP.

[0015] In the present invention, the method for determining the mass fraction (a) of DMVSP in the electrolyte solution is not subject to any restrictions, and those skilled in the art can determine the mass fraction (a) of DMVSP in the electrolyte solution using conventional technical means. For example, the mass fraction (a) of DMVSP in the electrolyte solution can be determined using the following method: A battery charging and discharging device is used to discharge the battery under the following discharge conditions: current 0.33 C, cut-off voltage 2.5 V, noting the battery number / barcode; The battery is disassembled in a glove box and the electrolyte solution is obtained (interior parameters to be met: H2O ≤ 0.1 ppm, O2 ≤ 0.1 ppm); A magnetic resonance spectrometer is used to check whether DMVSP is present in the electrolyte solution, and if so, a gas chromatograph is used to check the mass fraction of DMVSP in the electrolyte solution.

[0016] Disassembling the battery and obtaining the electrolyte solution can be carried out according to the following three methods: ① After opening the battery cover plate, if there is sufficient free electrolyte solution (ie more than 10 ml, also applies below), the electrolyte solution is transferred into a sample tube with a pipette, then sealed with sealing film; ② After opening the battery cover plate, if there is not enough free electrolyte solution, a hydraulic press (e.g., hydraulic press FY-30 of Beijing Hengaode Technology Co., Ltd.) can be used to continuously apply pressure until free electrolyte solution appears, collect the electrolyte solution in a sample tube, and then seal it with sealing film; 3. After opening the battery plate, if sufficient electrolyte solution cannot be obtained by methods 1 and 2, extraction tests shall be carried out, specifically as follows: 2 g / Ah to 5 g / Ah of a mixture of dichloromethane and cyclohexylbenzene (1:9 by volume) shall be added to the battery as an extractant, and the amount of extractant used shall be recorded. Then, the battery shall be placed in an aluminum-plastic bag, sealed with a heat sealant, and left to stand at a room temperature of 25 °C for 4 days to allow the electrolyte solution in the electrode film to fully mix with dichloromethane. Then, use a pipette to transfer the mixture of extractant and electrolyte solution into a 5 ml sample tube and seal the sample tube with a sealing film.

[0017] The mass fraction of DMVSP in the electrolyte solution can be tested using a gas chromatograph (Thermo Fisher Trace-1610) using the following method: the obtained sample of the electrolyte solution is injected into a 2 ml injection vial using a microsyringe, the response curve of the electrolyte solution sample is examined and compared with the DMVSP standard curve (obtained by performing the same test with pure DMVSP) to obtain the mass fraction of DMVSP in the electrolyte solution.

[0018] The method for testing whether DMVSP is present in the electrolyte solution using a magnetic resonance spectrometer is as follows: 1 ml of the collected electrolyte solution sample is placed in a sample tube, 0.5 ml of CDCl3 (deuterated chloroform) is injected into the sample tube with a syringe to completely dissolve the sample, and the magnetic resonance spectrometer (Bruker 400MHz NMR spectrometer) is used to examine the magnetic resonance spectrum of the electrolyte solution and compare it with the DMVSP standard curve (which was obtained by performing the same test on pure DMVSP) to help confirm whether DMVSP is present in the electrolyte solution or not.

[0019] Lithium iron phosphate batteries typically use a mixed solution containing lithium hexafluorophosphate in ethylene carbonate and ethyl methyl carbonate as the electrolyte solution. The contact angle (b) between the positive active material layer and the solution reflects the wettability of the positive electrode foil with the electrolyte solution. Reducing the contact angle (b) between the positive active material layer and the solution can improve the wettability of the positive electrode foil with the electrolyte solution, which contributes to reducing the ionic resistance of the positive electrode foil and thereby lowering the DCR value of the battery, and also increases the contact area between the electrolyte solution and the positive electrode foil.The contact angle (b) between the positive active material layer and the solution can be adjusted by modifying the type of carbon source and / or the amount of carbon coating and the compaction density of the positive electrode foil during the carbon coating process of the positive active material.

[0020] In the present invention, the method for determining the contact angle (b) between the positive active material layer and the solution is not limited, and those skilled in the art can perform the determination using conventional technical means. For example, the contact angle (b) can be measured using a contact angle measuring device (Beijing Zhongyi Kexin Technology Co., Ltd. JC2000D2M), and the specific testing method is as follows: 1) Pretreatment of the positive electrode foil: After disassembling the discharged battery, a positive electrode foil of about 8.5 cm * 8 cm in size is cut out with ceramic scissors to keep the positive electrode foil at room temperature of 25 °C for 6 h to 10 h, after which both ends of the electrode foil are attached to the testing device to start the testing; 2) the device with the attached electrode foil is placed on the sample support of the contact angle measuring device; 3) The solution is dropped toward the electrode foil with a syringe, and the contact angle is measured within 0.01 s to 0.05 s after the solution is dropped onto the foil. The contact angle is calculated using the five-point fitting method and an image evaluation method; the solution preparation method consists of mixing ethylene carbonate EC and ethyl methyl carbonate EMC with a mass ratio of 3:7, followed by adding lithium hexafluorophosphate to adjust its concentration to 1 mol / L.

[0021] The powder resistance (c) of the positive active material layer is related to the electron conductivity of the positive electrode foil and the wettability of the positive electrode foil with the electrolyte solution. Reducing the powder resistance (c) can improve the electron conductivity of the positive electrode foil, improve the DCR value of the battery, and also improve the wettability of the positive electrode foil with the electrolyte solution. The powder resistance (c) of the positive active material can be adjusted by modifying the particle size of the positive powder and the ratio of conductive agent to binder in the positive slurry.

[0022] In the present invention, the method for determining the powder resistance (c) of the positive active material layer is not limited, and those skilled in the art can perform the determination using conventional technical means. For example, the powder resistance (c) can be determined using the following method: The battery is discharged at 0.33 C, disassembled, the positive electrode foil is placed in a fume hood for 24 hours, after which 1 g of positive powder is collected using a scraper, the obtained positive powder is ball-milled for 20 to 40 minutes at 300 rpm using 0.6 mm diameter zirconium balls with a ball-to-powder ratio of 5:1, and then placed on a four-sensor resistance meter (e.g., Suzhou Jinggrid Electronics Co., Ltd. ST2722 Powder Resistance Tester for Semiconductors) to examine the powder resistance. The detailed procedure is as follows: the powder is placed on the electrode, a pressure of 10 MPa is applied to the powder using the other electrode, and the powder resistance value is read.

[0023] The mass fraction of DMVSP in the electrolyte solution, the contact angle between the positive active material layer and the solution, and the powder resistance of the positive active material layer all affect the DCR and gas generation of the battery to varying degrees and influence each other to some extent. Targeting a single variable makes it difficult to achieve both low DCR and low gas generation in the battery.The present invention achieves both low gas generation and low DCR by adjusting the mass fraction of DMVSP in the electrolyte solution, the contact angle between the positive active material layer and the solution, and the powder resistance of the positive active material layer to satisfy the above-mentioned specific relationship, resulting in fewer side reactions during cycling, lower gas generation, and higher conductivity of the positive electrode foil for ions and electrons, so that the battery can have both low gas generation and low DCR.

[0024] Example: The value of a × b × c can be chosen from 0.4, 0.6, 0.8, 1.0, 1.1, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 115, 120, 123 or any range formed by any two of these values.

[0025] In a preferred embodiment, the battery satisfies the following relationship: 0.5 ≤ a × b × c ≤ 16. By deliberately maintaining the value of a × b × c within this range, the battery exhibits a lower DCR value, fewer side reactions, and lower gas generation.

[0026] In some embodiments, the positive active material layer further contains a pre-lithiation additive.

[0027] In a preferred embodiment, the pre-lithiation additive contains lithium-rich iron lithiate (LFO). If the pre-lithiation additive contains lithium-rich iron lithiate, after disassembling the discharged battery, the positive electrode foil is removed, washed with DMC (dimethyl carbonate) for 4 to 5 hours, then left to stand for 3 hours at 45 °C, after which Fe 4+ can be determined using XPS analysis (X-ray photoelectron spectroscopy).

[0028] In one embodiment, the mass fraction of the pre-lithiation additive in the positive active material layer is 0.001 to 0.05. For example, the mass fraction of the pre-lithiation additive in the positive active material layer may be 0.001, 0.003, 0.005, 0.007, 0.01, 0.02, 0.03, 0.04, 0.05, or any range formed by any two of these values.

[0029] In some embodiments, the positive active material further comprises at least one of lithium manganese iron phosphate and ternary material (NCM / NCA). When the positive active material contains at least one of lithium manganese iron phosphate and ternary material, the upper voltage limit of the positive electrode foil can be increased. The sum of the mass fractions of lithium manganese iron phosphate and the ternary material in the positive active material layer is 0.02 to 0.5, such as 0.02, 0.05, 0.07, 0.1, 0.2, 0.3, 0.4, 0.5, or any range formed by any two of these values.

[0030] The mass fraction of lithium manganese iron phosphate in the positive active material layer can be selected to be 0.02 to 0.5, such as 0.02, 0.05, 0.07, 0.1, 0.2, 0.3, 0.4, 0.5, or any range formed by any two of these values; the chemical formula of lithium manganese -Iron phosphate is LiMn e Fe 1-ePO4, where 0 < e < 1, such as 0.01, 0.03, 0.05, 0.07, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.93, 0.96, 0.99 or any range formed by any two of these values; the particle size Dv50 of the lithium manganese iron phosphate is 2 µm to 3 µm, such as 2 µm, 2.2 µm, 2.4 µm, 2.6 µm, 2.8 µm, 3 µm or any range formed by any two of these values. The present invention imposes no restrictions on the method for determining the particle size Dv50 of lithium manganese iron phosphate, and those skilled in the art can determine the particle size Dv50 of lithium manganese iron phosphate using conventional technical means. For example, the particle size Dv50 of lithium manganese iron phosphate can be determined using the following method: the battery is discharged at 0.33 C to 2.5 V, disassembled, and the positive electrode foil is left for 24 hours.long in a fume hood to then collect 0.1 to 0.2 g of positive powder with a scraper, take SEM (scanning electron microscope) images of the obtained positive powder, measure the particle size of the lithium manganese phosphate particles in the SEM images using the MEASURE NANO software, obtain the particle size data using the diagonal line method, evaluate the particle size distribution after collecting 100 samples, so that the particle size parameter Dv50 of the lithium manganese iron phosphate can be calculated.

[0031] The mass fraction of the ternary material in the positive active material layer can be selected to be 0.02 to 0.5, such as 0.02, 0.05, 0.07, 0.1, 0.2, 0.3, 0.4, 0.5, or any range formed by any two of these values; the ternary material is LiNi x Co y Mn (1-x-y)O2, where 0 <x<1 ist (wie etwa 0,01, 0,03, 0,05, 0,07, 0,1, 0,2, 0,3, 0,4, 0,5, 0,6, 0,7, 0,8, 0,9, 0,93, 0,96, 0,99 oder ein beliebiger Bereich, der durch beliebige zwei dieser Wert gebildet wird); 0<y<1 ist (wie etwa 0,01, 0,03, 0,05, 0,07, 0,1, 0,2, 0,3, 0,4, 0,5, 0,6, 0,7, 0,8, 0,9, 0,93, 0,96, 0,99 oder ein beliebiger Bereich, der durch beliebige zwei dieser Wert gebildet wird) die Partikelgröße Dv50 des ternären Materials beträgt 3 µm bis 20 µm, wie etwa 3 µm, 5 µm, 7 µm, 10 µm, 12 µm, 14 µm, 16 µm, 18 µm, 20 µm oder ein beliebiger Bereich, der durch beliebige zwei dieser Wert gebildet wird. In der vorliegenden Erfindung unterliegt das Verfahren zur Bestimmung der Partikelgröße Dv50 des ternären Materials keinerlei Einschränkungen, und Fachleute können die Bestimmung gemäß herkömmlichen technischen Mitteln durchführen.For example, the particle size Dv50 of the ternary material can be determined using the following method: the battery is discharged at 0.33 C to 2.5 V, disassembled, the positive electrode foil is placed in a fume hood for 24 hours, then 0.1 to 0.2 g of positive powder is collected using a scraper, SEM (scanning electron microscope) images of the collected positive powder are taken, the particle size of the ternary particles in the SEM images are measured using the MEASURE NANO software, the particle size data are obtained using the diagonal line method, and the particle size distribution is evaluated after collecting 100 samples, so that the particle size parameter Dv50 of the ternary material can be calculated.

[0032] In some embodiments, c is in the range of 1 Ω·cm to 200 Ω·cm. For example, c can be 1 Ω cm, 3 Ω cm, 5 Ω cm, 7 Ω cm, 10 Ω cm, 15 Ω cm, 20 Ω cm, 25 Ω cm, 30 Ω cm, 35 Ω cm, 40 Ω cm, 45 Ω cm, 50 Ω cm, 60 Ω cm, 70 Ω cm, 80 Ω cm, 90 Ω cm, 100 Ω cm, 110 Ω cm, 120 Ω cm, 130 Ω cm, 140 Ω cm, 150 Ω cm, 160 Ω cm, 170 Ω cm, 180 Ω cm, 190 Ω·cm, 200 Ω·cm or any range formed by any two of these values.

[0033] When c is in the range of 1 Ω cm to 200 Ω cm, not only is the wettability of the positive electrode foil to the electrolyte solution in a more appropriate range with less side reactions between the positive electrode foil and the electrolyte solution and less gas generation, but also the conductivity of the positive electrode foil for electrons is higher and the DCR value of the battery is lower.

[0034] In a preferred embodiment, c is 5 Ω·cm to 50 Ω·cm. When c is within this range, it proves more advantageous for achieving a balance between the battery's gas production and its DCR value.

[0035] In some embodiments, b is 10° to 40°. For example, b may be 10°, 13°, 15°, 17°, 20°, 22°, 25°, 28°, 30°, 32°, 35°, 37°, 40°, or any range formed by any two of these values.

[0036] When b is within the range of 10° to 40°, the wetting rate of the positive electrode foil to the electrolyte solution is in a more appropriate range, where not only is there less risk of the positive electrode foil undergoing side reactions with the electrolyte solution, but also the internal ionic resistance of the battery is lower and the DCR value of the battery is lower.

[0037] In some embodiments, a is 0.0001 to 0.05. For example, a may be 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, or any range formed by any two of these values.

[0038] When a is in the range of 0.0001 to 0.05, the battery has lower gas generation and a lower DCR value.

[0039] In a preferred embodiment, a is 0.001 to 0.01. When a is within this range, it proves more advantageous for achieving a balance between the battery's gas production and its DCR value.

[0040] In some embodiments, the particle size Dv50 of the lithium iron phosphate is 0.1 µm to 2 µm, such as 0.1 µm, 0.5 µm, 0.7 µm, 1 µm, 0.3 µm, 1.2 µm, 1.5 µm, 1.7 µm, 2 µm, or any range formed by any two of these values. By deliberately maintaining the particle size Dv50 of the lithium iron phosphate within this specific range, it is ensured that the contact angle of the solution on the surface of the positive electrode foil is within a suitable range, while maintaining good porosity in the positive active material layer, improving the wetting rate of the electrolyte solution to the positive electrode foil, and reducing ionic resistance. In the present invention, the method for determining the particle size Dv50 of lithium iron phosphate is not subject to any restrictions, and those skilled in the art can carry out the determination according to conventional technical means.For example, the particle size Dv50 of lithium iron phosphate can be determined using the following method: the battery is discharged at 0.33 C to 2.5 V, disassembled, the positive electrode foil is placed in a fume hood for 24 hours, and then 0.1 to 0.2 g of positive powder is collected using a scraper. SEM images of the collected positive powder are taken. The particle size of the lithium iron phosphate particles in the SEM images is measured using the MEASURE NANO software. The particle size data are obtained using the diagonal line method. After collecting 100 samples, the particle size distribution is evaluated, so that the particle size parameter Dv50 of lithium iron phosphate can be calculated.

[0041] In some embodiments, the compaction density of the positive electrode foil is 2.0 g / cm 3 up to 3.0 g / cm 3 , such as 2.0 g / cm 3 , 2.2 g / cm 3 , 2.4 g / cm 3 , 2.6 g / cm 3, 2.8 g / cm 3 , 3.0 g / cm 3 or corresponds to any range formed by any two of these values. When the compaction density of the positive electrode foil is deliberately maintained within this specific range, the wettability of the positive electrode sheet surface to the electrolyte solution is good, which can reduce the ionic resistance of the entire battery. Since the areal density is within a suitable range, the energy density of the battery is satisfactorily ensured.

[0042] In the present invention, the method for determining the degree of compaction is not subject to any restrictions, and those skilled in the art can perform the determination using conventional technical means. For example, the compaction density of the positive electrode foil can be determined using the following method: The battery is discharged at 0.33 C to the cut-off voltage of 2.5 V and, after disassembling the battery, the positive electrode foil is placed in a fume hood for 24 h, the positive electrode foil is cut into a circular foil with a diameter of 4 cm, the original mass is recorded as m1 and the area as s1, the mass of the positive current collector of the same size is measured as m2, the areal density d is calculated using the formula d=(m1-m2) / s1, the thickness h1 of the positive active material layer in the positive circular foil is measured, the compaction density is calculated using the formula compaction ratio = d / h1.

[0043] In some embodiments, the mass fraction of the positive active material in the positive active material layer is 0.95 to 0.998, such as 0.95, 0.955, 0.96, 0.965, 0.97, 0.975, 0.98, 0.985, 0.99, 0.995, 0.998, or any range formed by any two of these values.

[0044] In addition to the positive active material, the positive active material layer also contains conductive agents and binders.

[0045] The conductive agent in the positive active material layer is used to provide conductivity. Any conductive agent can be used without any particular restrictions, as long as it has suitable conductivity for electrons and does not cause significant harmful chemical changes in the battery. Examples of conductive agents in the positive active material layer include, among others, carbon nanotubes, carbon black, graphite, carbon fiber, activated carbon, mesoporous carbon, and fullerenes. Carbon fiber includes carbon nanotubes, etc.; carbon black includes acetylene black, Ketjen black, Super P (i.e., SP), etc.

[0046] In some embodiments, the mass fraction of the conductive agent in the positive active material layer is 0.001 to 0.02, such as 0.001, 0.003, 0.005, 0.007, 0.01, 0.012, 0.015, 0.017, 0.02, or any range formed by any two of these values.

[0047] The binder in the positive active material layer is used to improve the adhesion between positive active material particles and the adhesion between the positive active material and the positive current collector. Any binder can be used without any particular restrictions, as long as it has suitable bonding properties and does not cause significant harmful chemical changes in the battery. Examples of binders in the positive active material layer include, but are not limited to, fluoropolyolefin binders, including polyvinylidene fluoride (PVDF), vinylidene fluoride copolymers, or their modified derivatives (e.g., modified with carboxylic acid, acrylic acid, acrylonitrile, etc.).

[0048] In some embodiments, the mass fraction of the binder in the positive active material layer is 0.001 to 0.05, such as 0.001, 0.003, 0.005, 0.007, 0.01, 0.02, 0.03, 0.04, 0.05, or any range formed by any two of these values.

[0049] In the present invention, the positive current collector is not particularly limited as long as it has electrical conductivity and does not cause adverse chemical changes in the battery, and may use, for example, aluminum, nickel, titanium, stainless steel, sintered carbon; or aluminum or stainless steel that has undergone a surface treatment with one of carbon, nickel, titanium, silver, etc.

[0050] The method for producing the positive active material is not particularly limited in the present invention, and those skilled in the art can produce the positive active material by conventional means.

[0051] The positive active material can be produced, for example, by the following method: iron phosphate, a carbon source, and lithium carbonate are mixed in an organic solvent at a mass ratio of 1:(0.15 to 0.35):0.09. This is followed by spray drying to obtain the raw material. The raw material is sintered at 650 to 800°C for 1 to 5 hours to obtain the positive active material. The carbon source can be selected from at least one of glucose, sucrose, and polyethylene glycol. The organic solvent can be selected from at least one of methanol and ethanol. After sintering, crushing or crushing and sieving operations can be performed.

[0052] Alternatively, the positive active material can be prepared using the following method: iron phosphate and lithium carbonate are mixed in an organic solvent at a mass ratio of 1:0.09, followed by spray drying to obtain the raw material, and the raw material is sintered at 650 to 800 °C for 1 to 5 hours to obtain the positive active material. The organic solvent can be selected from at least one of methanol and ethanol.

[0053] After sintering, crushing or crushing and sieving operations can be performed. The positive active material can also be obtained directly from commercially available lithium iron phosphate, for example, directly using lithium iron phosphate from Beijing EASPRING Material Technology Co., Ltd.

[0054] The positive active material can also be prepared by mixing lithium iron phosphate with at least one of lithium manganese iron phosphate and a ternary material. The lithium iron phosphate can either be purchased directly from a commercial source, such as Beijing EASPRING Material Technology Co., Ltd., or prepared using the methods described in the examples above.

[0055] The method for producing the positive electrode foil in the present invention is not particularly limited, and those skilled in the art can produce the positive electrode foil using conventional means. The method for producing the positive electrode foil includes, for example, the following steps: The positive active material, the conductive agent, and the binder are dispersed in a solvent, which may be N-methylpyrrolidone (NMP) or deionized water, to form a uniform positive slurry, the positive slurry is coated on the positive current collector, and the positive electrode foil is obtained by operations such as rolling.

[0056] The battery of the present invention also includes a negative electrode foil containing a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector.

[0057] The negative active material in the present invention is not particularly limited. For example, the negative active material includes natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, SiO g(0 <g<2, wie etwa g=1), Silicium-Kohlenstoff- Verbundstoff, Li4Ti5O 12 .

[0058] In some embodiments, the mass fraction of the negative active material in the negative active material layer is 0.93 to 0.998, such as 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.993, 0.995, 0.998, or any range formed by any two of these values.

[0059] In some embodiments, the negative active material includes graphite, and the particle size Dv50 of the graphite is 5 µm to 20 µm, such as 8 µm, 10 µm, 12 µm, 14 µm, 16 µm, 20 µm, 22 µm, 25 µm, or any range formed by any two of these values.

[0060] The negative active material layer may also contain a conductive agent and / or a binder.

[0061] The conductive material in the negative active material layer is used to provide conductivity. Any conductive material can be used without any particular restrictions, as long as it has suitable conductivity for electrons and does not cause significant harmful chemical changes in the battery. Examples of conductive materials in the negative active material layer include, among others, carbon nanotubes, carbon black, graphite, carbon fiber, activated carbon, mesoporous carbon, and fullerenes. Carbon fiber includes carbon nanotubes, etc.; carbon black includes acetylene black, Ketjen black, Super P (i.e., SP), etc.

[0062] In some embodiments, the mass fraction of the conductive agent in the negative active material layer is 0.001 to 0.02, such as 0.001, 0.003, 0.005, 0.007, 0.01, 0.012, 0.014, 0.016, 0.018, 0.02, or any range formed by any two of these values.

[0063] The binder in the negative active material layer is used to improve the adhesion between the negative active material particles and the adhesion between the negative active material and the negative current collector. Any binder can be used without any particular restrictions, as long as it has suitable bonding properties and does not cause significant harmful chemical changes in the battery. For example, the binder in the negative active material layer includes at least one of carboxymethyl cellulose (CMC), styrene-butadiene rubber, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, and water-based acrylic resin.

[0064] In some embodiments, the mass fraction of the binder in the negative active material layer, based on the weight of the negative active material layer, is 0.001 to 0.05, such as 0.001, 0.003, 0.005, 0.007, 0.01, 0.02, 0.03, 0.04, 0.05, or any range formed by any two of these values.

[0065] The negative current collector in the present invention is not particularly limited as long as it has electrical conductivity and does not cause adverse chemical changes in the battery, and may be used, for example, as follows: copper, stainless steel, aluminum, nickel, titanium, sintered carbon; copper or stainless steel that has undergone a surface treatment with at least one of carbon, nickel, titanium, silver; or aluminum-cadmium alloy.

[0066] The method for producing the negative electrode foil in the present invention is not particularly limited, and those skilled in the art can produce the negative electrode foil using conventional means. The method for producing the negative electrode foil includes, for example, the following steps: The negative active material, the conductive agent, and the binder are dispersed in a solvent, which may be N-methylpyrrolidone (NMP) or deionized water, to form a uniform negative slurry, the negative slurry is coated on the negative current collector, and the negative electrode foil is obtained by operations such as rolling.

[0067] The electrolytic solution of the present invention further contains a solvent. The solvent includes, among others, at least one of ethylene carbonate (EC), methylenemethanedisulfonate (MMDS), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), propylene carbonate (PC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), γ-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0068] The mass fraction of the solvent in the electrolyte solution can be chosen to be from 0.65 to 0.98889, such as 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 0.98, 0.9889, or any range formed by any two of these values.

[0069] In some embodiments, the electrolyte solution further contains methylenemethane disulfonate, wherein the mass fraction of methylenemethane disulfonate in the electrolyte solution is 0.00001 to 0.05, such as 0.00001, 0.00005, 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.03, 0.05, or any range formed by any two of these values. The addition of methylenemethane disulfonate in the above-mentioned specific amount can reduce the required amount of DMVSP and further lower the ionic resistance.

[0070] The electrolyte solution also contains electrolyte salt, which typically includes lithium salt. The lithium salt includes, for example, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluoro(bisoxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP), among others. The mass fraction of the electrolyte salt in the electrolyte solution can be selected to be 0.01 to 0.2, such as 0.01, 0.03, 0.05, 0.07, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, or any range formed by any two of these values.

[0071] In addition, the electrolyte solution may also contain other additives. These additives may include, for example, additives for the formation of the negative electrode foil, additives for the formation of the positive electrode foil, and additives for improving certain battery performance characteristics, such as additives for improving the battery's high-temperature performance, additives for improving overcharge behavior, additives for improving battery performance at low temperatures, etc.

[0072] The method for preparing the electrolyte solution in the present invention is not particularly limited, and those skilled in the art can prepare it using conventional means. The method for preparing the electrolyte solution includes, for example, the following steps: Solvent, lithium salt, DMVSP and other additives (if present) are mixed to obtain the electrolyte solution.

[0073] The battery may further include a separator located between the positive and negative electrode foils, which serves to separate the positive and negative electrode foils and prevent a short circuit between the positive and negative electrode foils. The separator may be any separator foil material suitable for batteries of this technical field. For example, the separator includes, among others, at least one of polypropylene (PP) and polyethylene (PE). Electrical device

[0074] The present invention also provides an electrical device that includes the battery. The battery serves as a power supply for the electrical device.

[0075] An electrical device can be any device that can harness electrical energy and convert it into other forms of energy, such as mechanical energy, thermal energy, light energy, etc. The converted energy can be in one form or more than two forms. For example, an electrical device includes at least one of electric vehicles, electric trains, mobile devices, ships and satellites, energy storage systems, etc. Examples of electric vehicles include, but are not limited to, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.; mobile devices include, but are not limited to, mobile phones, laptops, drones, robot vacuums, etc.

[0076] The following examples further illustrate the present invention. Example 1

[0077] Example 1 provides a battery manufactured by the following method: (1) Preparation of the positive electrode foil (1.1) Preparation of lithium iron phosphate

[0078] Iron phosphate, a carbon source, and lithium carbonate are mixed in methanol in a mass ratio of 1:0.25:0.09, followed by spray drying to obtain a raw material, sintering the raw material at 700 °C for 3 hours, ball milling (with zirconium balls of 0.6 mm diameter, ball-to-powder ratio 5:1, speed 300 rpm), and sieving to obtain carbon-coated lithium iron phosphate, where the carbon source is glucose. (1.2) Preparation of the positive electrode foil

[0079] The obtained lithium iron phosphate is used as a positive active material, wherein the positive active material, the conductive agent acetylene black and the binder PVDF are mixed in a mass ratio of 96.3:0.7:3.0, dispersed in NMP to obtain a positive slurry, the positive slurry is coated on both sides of the aluminum foil, ensuring that the wet film thickness of the positive slurry on one side of the aluminum foil is 120 μm, followed by rolling and cutting to obtain the positive electrode foil, wherein the compaction density of the obtained positive electrode foil is shown in Table 1. (2) Production of the negative electrode foil

[0080] Artificial graphite, the binder carboxymethyl cellulose, and the conductive agent conductive carbon black are dispersed in deionized water at a mass ratio of 95.8:1.2:3.0 to prepare a negative slurry. The negative slurry is then coated on both sides of a copper foil, ensuring that the wet film thickness of the negative slurry on one side of the copper foil is 180 µm; then, it is rolled and cut to obtain the negative electrode foil. (3) Preparation of the electrolyte solution

[0081] A solvent, tris-(dimethylvinylsilyl)phosphate and lithium hexafluorophosphate are mixed in a mass ratio of 0.9599:0.0051:0.035 to obtain the electrolyte solution;

[0082] The solvent is prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a volume ratio of 3:4:3. (4) Manufacture of the separator

[0083] A PE separator is used. (5) Assembly and construction

[0084] The above-mentioned positive electrode foil, separator, and negative electrode foil are stacked in this order, with the separator sandwiched between the positive and negative electrode sheets for insulation, followed by winding to obtain a bare cell; and the bare cell is inserted into an outer packaging shell, followed by drying and injection of the electrolyte solution, followed by vacuum packaging, standing time, and assembly, thereby obtaining a lithium-ion battery. Examples 2 to 17 and Comparative Examples 1 to 4

[0085] Examples 2 to 17 and Comparative Examples 1 to 4 each provide a battery having similar manufacturing methods to Example 1, except that: in step (1.1), the mass ratio of iron phosphate, the carbon source and lithium carbonate as well as the ball milling and sieving process are adjusted, the mass ratio of iron phosphate, the carbon source and lithium carbonate as well as the particle size Dv50 of the obtained lithium iron phosphate being listed in Table 1; in step (1.2), the mass ratio of the positive active material, the conductive agent and the binder as well as the compaction density of the obtained positive electrode foil are listed in Table 1; in step (3) the mass fraction of DMVSP in the electrolyte solution is adjusted and the mass fraction of solvent in the electrolyte solution is adjusted accordingly, wherein the mass fraction of DMVSP in the electrolyte solution is listed in Table 1. Example 18 and Comparative Examples 7 to 8

[0086] Example 18 and Comparative Examples 7 to 8 each provide a battery using similar manufacturing methods to Example 1, except that: in step (1.1), the ball milling and sieving process is adapted, the particle size Dv50 of the resulting lithium iron phosphate being listed in Table 1; in step (1.2) the resulting lithium iron phosphate is used together with lithium manganese iron phosphate as a positive active material, the weight of lithium manganese iron phosphate is 5% of the weight of lithium iron phosphate, the chemical formula of the lithium manganese iron phosphate used is LiMn0,4 Fe 0,6 PO4 and its particle size Dv50 is 2.6 µm, wherein the mass ratio of positive active material, conductive agent and binder as well as the compaction density of the obtained positive electrode foil are listed in Table 1; in step (3) the mass fraction of DMVSP in the electrolyte solution is adjusted and the mass fraction of solvent in the electrolyte solution is adjusted accordingly, wherein the mass fraction of DMVSP in the electrolyte solution is listed in Table 1. Example 19 and Comparative Examples 9 to 10

[0087] Example 19 and Comparative Examples 9 to 10 each provide a battery using similar manufacturing methods to Example 1, except that: in step (1.1), the ball milling and sieving process is adapted, the particle size Dv50 of the resulting lithium iron phosphate being listed in Table 1; in step (1.2) the resulting lithium iron phosphate is used together with ternary material as positive active material, the weight of the ternary material is 5% of the weight of lithium iron phosphate, the chemical formula of the ternary material used is LiNi 0,2 Co 0,3 Mn 0,5 O2 and its particle size Dv50 is 13 µm, wherein the mass ratio of positive active material, conductive agent and binder as well as the compaction density of the obtained positive electrode foil are listed in Table 1; in step (3) the mass fraction of DMVSP in the electrolyte solution is adjusted and the mass fraction of solvent in the electrolyte solution is adjusted accordingly, wherein the mass fraction of DMVSP in the electrolyte solution is listed in Table 1. Examples 20 to 21 and Comparative Examples 5 to 6

[0088] Examples 20 to 21 and Comparative Examples 5 to 6 each provide a battery using similar manufacturing methods to Example 1, except that: in step (1.1), the ball milling and sieving process is adapted, the particle size Dv50 of the resulting lithium iron phosphate being listed in Table 1; in step (1.2), the positive active material, a pre-lithiation additive, a conductive agent, the conductive agent acetylene black and the binder PVDF are mixed to produce a positive slurry, wherein the mass ratio of positive active material, pre-lithiation additive, conductive agent and binder as well as the compaction density of the obtained positive electrode foil are listed in Table 1, wherein the pre-lithiation additive is lithium-rich iron lithiate; in step (3) the mass fraction of DMVSP in the electrolyte solution is adjusted and the mass fraction of solvent in the electrolyte solution is adjusted accordingly, wherein the mass fraction of DMVSP in the electrolyte solution is listed in Table 1. Example 22

[0089] Example 22 provides a battery using a similar manufacturing method as Example 1, except that: in step (1.1), the ball milling and sieving process is adapted, the particle size Dv50 of the resulting lithium iron phosphate being listed in Table 1; in step (1.2), the compaction density of the obtained positive electrode foil is listed in Table 1; in step (3) solvent, tris-(dimethylvinylsilyl)phosphate, lithium hexafluorophosphate and methylenemethanedisulfonate are mixed to prepare the electrolyte solution, wherein the mass fraction of DMVSP in the electrolyte solution is listed in Table 1, the mass fraction of methylenemethanedisulfonate in the electrolyte solution is 0.003, the mass fraction of lithium hexafluorophosphate in the electrolyte solution remains unchanged. Examples 23 to 27 and Comparative Examples 11 to 12

[0090] Examples 23 to 27 and Comparative Examples 11 to 12 each provide a battery using similar manufacturing methods to Example 1, except that: in step (1.1) no carbon source is used, the ball milling and sieving process is adapted, the mass ratio of iron phosphate to lithium carbonate and the particle size Dv50 of the lithium iron phosphate obtained being listed in Table 1; in step (1.2), the mass ratio of the positive active material, the conductive agent and the binder as well as the compaction density of the obtained positive electrode foil are listed in Table 1; in step (3) the mass fraction of DMVSP in the electrolyte solution is adjusted and the mass fraction of solvent in the electrolyte solution is adjusted accordingly, wherein the mass fraction of DMVSP in the electrolyte solution is listed in Table 1.

[0091] The following methods were used to determine the mass fraction a of DMVSP in the electrolyte solution, the contact angle b between the positive active material layer and the solution, and the powder resistance c of the positive active material layer in each of the examples and comparative examples, with the test results shown in Table 1: (1) Mass fraction a of DMVSP in the electrolyte solution

[0092] The battery is discharged, discharge conditions: current 0.33 C, cut-off voltage 2.5 V, the battery number / barcode is recorded; the battery is disassembled in a glove box (indoor conditions to be met: H2O ≤ 0.1 ppm, O2 ≤ 0.1 ppm), after opening the battery cover plate, the electrolyte solution is obtained according to methods 1 to 3: ① if there is sufficient free electrolyte solution (ie more than 10 ml, also applies below), the electrolyte solution is transferred into a sample tube with a pipette, after which it is sealed with a sealing film; ② If sufficient electrolyte solution cannot be obtained by method ①, a hydraulic press (e.g., hydraulic press FY-30 from Beijing Hengaode Technology Co., Ltd.) is used to continuously apply pressure until free electrolyte solution appears, and the electrolyte solution is collected in a sample tube and sealed with sealing film; 3 If sufficient electrolyte solution cannot be obtained by methods 1 and 2, extraction tests shall be carried out, specifically as follows: 5 g / Ah of a mixture of dichloromethane and cyclohexylbenzene (volume ratio 1:9) shall be added to the battery as an extractant, and the amount of extractant used shall be recorded. Then, the battery shall be placed in an aluminum-plastic bag, sealed with a heat sealant, left to stand at a room temperature of 25 °C for 4 days to allow the electrolyte solution in the electrode film to fully mix with dichloromethane. Then, use a pipette to transfer the mixture of extractant and electrolyte solution into a 5 ml sample tube and seal the sample tube with a sealing film.

[0093] Next, a magnetic resonance spectrometer is used to check whether DMVSP is present in the electrolyte solution: 1 ml of the obtained electrolyte solution sample is placed in a sample tube, 0.5 ml of CDCl3 (deuterated chloroform) is injected into the sample tube using a syringe to completely dissolve the sample, and a magnetic resonance spectrometer (Bruker 400MHz NMR spectrometer) is used to examine the magnetic resonance spectrum of the electrolyte solution and compare it with the DMVSP standard curve (obtained by performing the same test with pure DMVSP) to help confirm whether DMVSP is present in the electrolyte solution.

[0094] If DMVSP has been detected in the electrolyte solution using a magnetic resonance spectrometer, a gas chromatograph (Thermo Fisher Trace-1610) is used to check the mass fraction according to the following method: the obtained sample of the electrolyte solution is injected into a 2 ml injection vial using a microsyringe, the response curve of the electrolyte solution sample is examined and compared with the DMVSP standard curve (obtained by performing the same test with pure DMVSP) to obtain the mass fraction of DMVSP in the electrolyte solution. (2) Contact angle b between positive active material layer and solution

[0095] Measured with a contact angle measuring device (Beijing Zhongyi Kexin Technology Co., Ltd. JC2000D2M), specific test method as follows: 1) Pretreatment of the positive electrode foil: after disassembling the discharged battery (using the discharge method of the testing process for the mass fraction a of DMSVP in the electrolyte solution), a positive electrode foil with a size of about 8.5 cm * 8 cm is cut out with ceramic scissors to keep the positive electrode foil at room temperature of 25 °C for 8 h, after which both ends of the electrode foil are attached to the testing device to start the testing; 2) the device with the attached foil is placed on the sample support of the contact angle measuring device; 3) The solution is dropped toward the film with a syringe, and the contact angle is measured 0.05 s after the solution drops fall onto the film. The contact angle is calculated using the five-point fitting method and the image evaluation method; the solution is prepared by mixing ethylene carbonate EC and ethyl methyl carbonate EMC with a mass ratio of 3:7, followed by adding lithium hexafluorophosphate to adjust its concentration to 1 mol / L. (3) Powder resistance c of the positive active material layer

[0096] The battery is discharged at 0.33 C, disassembled, and the positive electrode foil is placed in a fume hood for 24 hours. 1 g of positive powder is collected using a scraper. The collected positive powder is ball-milled for 20 minutes at 300 rpm using 0.6 mm diameter zirconium balls with a ball-to-powder ratio of 5:1. The powder is then applied to a four-sensor resistivity meter (Suzhou Jinggrid Electronics Co., Ltd. ST2722 Powder Resistance Tester for Semiconductors) to measure the powder resistance. The procedure is as follows: the powder is applied to the electrode, and pressure is applied to the powder using the other electrode. The pressure intensity is 10 MPa, consistent with the material, and the powder resistance value is read.

[0097] The batteries as shown in each of the examples and comparative examples were subjected to performance tests, the test results of which are shown in Table 1, using the following specific test methods: Gas generation at high temperatures: Charge at a constant current of 0.33 C up to the upper voltage limit of 3.65 V. Charge at a constant voltage until the current is less than or equal to 0.05 C. After full charge, the battery volume is measured using the water displacement method and recorded as V0. After the battery is placed in an oven at 60 °C for 48 hours, and after the battery temperature has dropped to room temperature of 25 °C, the battery volume is measured again using the water displacement method and recorded as V1. In order to calculate the gas generation during storage at 60 °C, the following formula is used: Gas generation during storage at 60 °C = (V1-V0) / battery capacity.

[0098] Specific method for measuring battery volume using the water displacement method: 1) an appropriate amount of pure water is added to the container and its density ρ is measured and recorded using a density meter; 2) the container is placed on the scale, the tare value is determined (before examining each of the cells, the tare value must be determined); 3) the cell body is immersed into the pure water together with the tabs, ensuring that the cell does not touch the container wall, after stabilization the data are read and recorded, noting these data as T0 before storage in the oven and T1 after storage in the oven; 4) the balance is turned off and the container is sealed to prevent evaporation of reagents.

[0099] V1-V0 is calculated using the following formula: V1-V0 = T1 / ρ - T0 / ρ.

[0100] DCR value: charge the battery at 0.33 C at constant current and constant voltage to 3.65 V, cut-off current 0.05 C; stand time 10 min, discharge at 0.33 C at constant current to 2.5 V, repeat this cycle twice, stand time 10 min, charge at 0.33 C at constant current and constant voltage to 3.65 V, discharge to 50% of the discharge capacity of the 2nd cycle, followed by a stand time of 2 h, discharge for 18 s at 1 C (discharge capacity of the 2nd cycle), recording the initial discharge voltage as V3, the voltage after 18 s of discharge is recorded as V4, and the discharge current after 18 s is recorded as I1, RDCR discharge (I1, 18s) = |V3-V4 / I1. Table 1 DMVSP mass share a Contact angle with the positive electrode foil, b / ° Mass ratio of iron phosphate, carbon source and lithium carbonate or mass ratio of iron phosphate and lithium carbonate in the production of lithium iron phosphate Degree of compaction of the positive electrode foil / g·cm -3 Powder resistance of the positive active material layer c / Ω·cm Lithium iron phosphate Dv50 / µm axbxc Positive active material : conductive agent : binder (mass ratio) or positive active material : conductive agent : binder : pre-lithiation additive (mass ratio) DCR / Ω Gas generation when stored at 60 °C / ml Ah -1 Example 1 0,0051 32,6 1:0,25:0,09 2,19 32,52 1,32 5,41 0,963:0,007:0,03 49,2 0,76 Example 2 0,0083 38,9 1:0,25:0,09 2,01 49,42 1,48 15,96 51,3 0,63 Example 3 0,0069 20,5 1:0,25:0,09 2,57 10,13 0,83 1,43 50,6 0,81 Example 4 0,0011 19,6 1:0,25:0,09 2,72 26,25 1,23 0,57 48,4 0,84 Example 6 0,0006 28,2 1:0,25:0,09 2,41 29,73 1,25 0,50 51,4 1,21 Example 7 0,0121 11,8 1:0,25:0,09 2,94 8,61 0,58 1,23 58,1 0,92 Example 8 0,0082 13,3 1:0,25:0,09 2,91 4,87 0,44 0,53 55,3 0,94 Example 9 0,0053 31,2 1:0,25:0,09 2,20 51,51 1,54 8,52 59,5 0,85 Example 10 0,0091 38,8 1:0,20:0,09 2,14 47,24 1,45 16,68 0,963:0,007:0,03 54,3 1,33 Example 11 0,0057 11,2 1:0,34:0,09 2,14 6,63 0,56 0,42 66,5 1,34 Example 12 0,0001 22,1 1:0,25:0,09 2,51 199,34 1,2 0,44 0,93:0,007:0,063 66,3 1,47 Example 13 0,0358 28,2 1:0,25:0,09 2,42 122,23 1,2 123,40 0,94:0,007:0,053 68,2 1,22 Example 14 0,0324 10,2 1:0,25:0,09 2,98 1,12 1,2 0,37 0,978:0,02:0,002 63,9 1,29 Example 15 0,0492 15,2 1:0,25:0,09 2,86 52,42 1,2 39,20 0,974:0,018:0,008 67,2 1,31 Example 16 0,0054 9,3 1:0,25:0,09 3,12 8,63 0,58 0,43 0,963:0,007:0,03 72,9 1,37 Example 17 0,0092 40,6 1:0,25:0,09 1,95 46,24 1,42 17,27 70,3 1,47 Example 18 0,0097 12,2 1:0,25:0,09 2,93 17,43 1,03 2,06 0,963:0,007:0,03 45,3 1,02 Example 19 0,0092 23,4 1:0,25:0,09 2,49 5,92 0,53 1,27 0,963:0,007:0,03 45,2 1,1 Example 20 0,0014 38,7 1:0,25:0,09 2,03 46,38 1,46 2,51 0,963:0,007:0,022:0,008 42,9 0,85 Example 21 0,0081 35,3 1:0,25:0,09 2,11 43,43 1,42 12,42 45,6 1,03 Example 22 0,0039 20,5 1:0,25:0,09 2,57 10,13 0,83 0,81 0,963:0,007:0,03 50,2 0,85 Example 23 0,0041 30,6 1:0,09 2,21 31,52 1,32 3,95 0,963:0,007:0,03 63,21 1,23 Example 24 0,0083 39,3 1:0,09 2,01 49,02 1,48 15,99 65,35 1,08 Example 25 0,0033 12,5 1:0,09 2,91 12,13 0,83 0,50 58,91 1,34 Example 26 0,0021 12,6 1:0,09 2,9 13,25 0,94 0,35 69,23 1,52 Example 27 0,01 35,8 1:0,09 2,1 46,32 1,45 16,58 70,22 1,5 Example 28 0,0321 23,2 1:0,09 2,50 106,32 1,78 121,8 72,78 1,55 Comparison example 1 0,0002 10,2 1:0,25:0,09 3,00 103,92 1,72 0,21 0,963:0,007:0,03 84,8 1,72 Comparison example 2 0,0494 28,3 1:0,25:0,09 2,42 93,78 1,65 131,11 82,3 1,81 Comparison example 3 0,0623 10,3 1:0,25:0,09 3,00 0,22 0,05 0,14 83,1 1,86 Comparison example 4 0,0172 33,3 1:0,25:0,09 2,21 224,7 2,21 128,70 84,2 1,79 Comparison example 5 0,0613 10,3 1:0,25:0,09 3,00 0,25 0,06 0,16 0,963:0,007:0,022:0,008 85,3 1,63 Comparison example 6 0,0173 33,9 1:0,25:0,09 2,18 215,5 2,14 126,38 87,4 1,71 Comparison example 7 0,0594 13,3 1:0,25:0,09 2,91 0,31 0,07 0,24 0,963:0,007:0,03 81,7 1,56 Comparison example 8 0,0182 30,3 1:0,27:0,09 2,14 232,2 2,39 128,05 89,9 1,66 Comparison example 9 0,0564 10,3 1:0,25:0,09 3,00 0,31 0,07 0,18 84,2 1,85 Comparison example 10 0,0215 26,3 1:0,25:0,09 2,36 225,6 2,31 127,57 82,1 1,92 Comparison example 11 0,0621 10,5 1:0,25:0,09 3,02 0,24 0,06 0,16 0,963:0,007:0,03 83,78 1,89 Comparison example 12 0,0133 37,9 1:0,25:0,09 2,08 254,5 2,56 128,29 83,31 2,05

[0101] Batteries prepared according to various examples of the present invention exhibit a DCR value ≤ 73 Ω, a gas generation when stored at 60 °C ≤ 1.52 ml / Ah, which demonstrates that batteries containing the positive electrode foil of the present invention achieve both a low DCR value and low gas generation.

[0102] The comparison of Examples 1 to 5 with Comparative Examples 6 to 9 and of Examples 10 to 11 with Comparative Examples 12 to 15 shows that it is more favorable for the balance between the DCR value and the gas generation of the battery if the mass fraction a of DMVSP in the electrolyte solution and the powder resistance c of the positive swirl material layer satisfy the preferred ranges of the present invention.

[0103] Comparing Examples 1 to 9 with Examples 10 to 17 shows that the balance between the battery's DCR value and low gas generation is better when the battery satisfies 0.5 ≤ axbxc ≤ 16.

[0104] According to Comparative Examples 1 to 12, even when the mass fraction a of DMVSP in electrolyte solution, the contact angle b between the positive active material layer and the solution, and the powder resistance c of the positive active material layer are each within appropriate ranges, both the DCR value and the gas generation of the battery are relatively high when the value of a × b × c is outside the range of 0.3 to 124 (excluding the endpoint values).

[0105] Comparison of Example 22 with Example 3 shows that the addition of methylenemethanedisulfonate to the electrolyte solution can reduce the required amount of DMVSP while achieving a similar DCR and gas production.

[0106] Finally, it should be noted that the above-mentioned embodiments serve only to illustrate the technical solutions of the present disclosure and do not limit the scope thereof. Although a detailed description of the present invention has been provided with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope thereof.

Claims

[1] A battery comprising an electrolyte solution and a positive electrode foil, wherein the positive electrode foil has a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, wherein the positive active material layer contains a positive active material, wherein the positive active material comprises lithium iron phosphate, characterized by that the electrolyte solution contains tris-(dimethylvinylsilyl)phosphate; and the battery satisfies the following relationship: 0.3 < a × b × c < 124, where a is a mass fraction of tris-(dimethylvinylsilyl)phosphate in the electrolyte solution; b is the contact angle between the positive active material layer and the solution in units of degrees (°), wherein the solution consists of ethylene carbonate, ethyl methyl carbonate and lithium hexafluorophosphate, wherein the mass ratio of ethylene carbonate to ethyl methyl carbonate is 3:7 and the concentration of lithium hexafluorophosphate in the solution is 1 mol / l; and c is the powder resistance of the positive active material layer, in units of Ω·cm. [2] Battery according to claim 1, characterized by that the battery satisfies the following relationship: 0.50≤a×b×c≤16. [3] Battery according to claim 1 or 2, characterized by that the positive active material layer further comprises a pre-lithiation additive. [4] Battery according to claim 3, characterized by that the pre-lithiation additive comprises lithium-rich iron lithiate. [5] Battery according to one of the preceding claims, characterized bythat the positive active material further comprises at least one of lithium manganese iron phosphate and ternary material (NCM / NCA). [6] Battery according to one of the preceding claims, characterized by that c is 1 Ω·cm to 200 Ω·cm, preferably 5 Ω·cm to 50 Ω·cm. [7] Battery according to one of the preceding claims, characterized by that a is 0.0001 to 0.05, preferably 0.001 to 0.

01. [8] Battery according to one of the preceding claims, characterized by that b is 10° to 40°. [9] Battery according to one of the preceding claims, characterized by that the battery meets at least one of the following conditions: S1. the particle size Dv50 of the lithium iron phosphate is 0.1 µm to 2 µm; S2. The compaction density of the positive electrode foil is 2.0 g / cm 3 up to 3.0 g / cm 3 ; S3. the electrolyte solution further contains methylenemethanedisulfonate, and the mass fraction of methylenemethanedisulfonate in the electrolyte solution is 0.00001 to 0.05; S4. the battery further comprises a negative electrode foil, wherein the negative electrode foil comprises a negative current collector and a negative active material layer arranged on at least one surface of the negative current collector, wherein the negative active material layer contains graphite and the particle size Dv50 of the graphite is 5 µm to 20 µm. [10] Electrical device, characterized by that it comprises the battery according to one of the preceding claims.