Lithium-ion battery and electric device

Abstract

Disclosed in the embodiments of the present application are a lithium-ion battery and an electric device. The lithium-ion battery comprises an electrolyte, wherein the electrolyte comprises a lithium salt, and the concentration c of the lithium salt in the electrolyte satisfies: c≥1 mol / L; the density ρ of the electrolyte satisfies: 0.9 g / mL≤ρ≤1.23 g / mL; and the charging time t of charging the lithium-ion battery from 10% SOC to 80% SOC satisfies 8.8 min≤t≤15 min: The lithium-ion battery has both good fast-charging capability and cycling performance.

Description

Lithium-ion batteries and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent document claims priority to and the benefit of Chinese patent application No. 202410303348.1, filed on March 18, 2024, entitled “Lithium-ion battery and power-consuming device.” The entire contents of the aforementioned patent application are incorporated by reference into this patent document. Technical Field

[0003] The present application relates to the field of batteries, and more specifically, to a lithium-ion battery and an electrical device. Background Art

[0004] In recent years, lithium-ion batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields, and have thus achieved great development.

[0005] With people's ever-increasing pursuit of efficiency, fast-charging lithium-ion batteries have become a key development priority. Concentration polarization during fast charging is more severe than that of standard lithium-ion batteries, causing cycle lifespan drops and severely threatening the service life and cycling stability of fast-charging lithium-ion batteries. Therefore, improving the cycling performance of fast-charging lithium-ion batteries is a pressing technical challenge. Summary of the Invention

[0006] The present application is made in view of the above technical problems, and its purpose is to provide a lithium-ion battery and an electrical device. The lithium-ion battery has a fast charging capability and can have good cycle performance under fast charging.

[0007] In a first aspect, a lithium-ion battery is provided, comprising: an electrolyte, the electrolyte comprising a lithium salt, wherein a concentration c of the lithium salt in the electrolyte satisfies: c ≥ 1 mol / L; a density ρ of the electrolyte satisfies: 0.9 g / mL ≤ ρ ≤ 1.23 g / mL; and a charging time t of the lithium-ion battery from 10% SOC to 80% SOC satisfies: 8.8 min ≤ t ≤ 15 min.

[0008] In an embodiment of the present application, the lithium-ion battery can be charged from 10% SOC to 80% SOC in a charging time of 8.8 minutes to 15 minutes. In other words, the lithium-ion battery is a fast-charging lithium-ion battery; and the fast-charging lithium-ion battery includes an electrolyte with a large lithium salt concentration and a low density. The large electrolyte concentration and low electrolyte density can improve the concentration polarization of the lithium-ion battery during the fast charging process, thereby improving the cycle performance of the fast-charging lithium-ion battery.

[0009] In one possible implementation, c≤1.8 mol / L.

[0010] In one possible implementation, 1.1 mol / L≤c≤1.6 mol / L.

[0011] In one possible implementation, 8.8 min≤t≤10 min.

[0012] In a possible implementation, the electrolyte includes a first solvent, and the first solvent includes at least one of ethylene carbonate, propylene carbonate, and ethyl methyl carbonate.

[0013] In the embodiments of the present application, by selecting a carbonate solvent with low viscosity and high dielectric constant as the first solvent, it is beneficial to the rapid migration of lithium ions in the electrolyte and the solubility of lithium salts in the electrolyte, thereby helping to improve the polarization of the lithium-ion battery during fast charging and enhance its stability during the cycle.

[0014] In a possible implementation, the electrolyte includes a second solvent, and the second solvent includes R1-COO-R2, wherein R1 and R2 independently include one of an alkyl group with 1 to 5 carbon atoms and a halogenated alkyl group with 1 to 5 carbon atoms.

[0015] In the embodiments of the present application, by selecting a carboxylic acid ester solvent with high ionic conductivity and low density as the second solvent, it helps to improve the density and conductivity of the electrolyte, so that the electrolyte is compatible with the fast charging capability of the lithium-ion battery, thereby obtaining a lithium-ion battery with both fast charging capability and good cycle stability.

[0016] In a possible implementation, the mass content X of the first solvent in the electrolyte satisfies: 20%≤X≤30%.

[0017] In a possible implementation, the mass content Y of the second solvent in the electrolyte satisfies: 20%≤Y≤60%.

[0018] In one possible implementation, the lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0019] In a possible implementation, the lithium salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, and the concentration of the lithium bis(fluorosulfonyl)imide in the electrolyte is less than or equal to 30%.

[0020] In the embodiments of the present application, by selecting a mixture of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide as the lithium salt and controlling the concentration ratio of lithium bis(fluorosulfonyl)imide, the low-temperature performance of the lithium-ion battery can be improved while reducing the possibility of the electrode plates being corroded by the electrolyte.

[0021] In a possible implementation, the conductivity σ of the electrolyte satisfies: 13 mS / cm≤σ≤20 mS / cm.

[0022] In a possible implementation, the viscosity μ of the electrolyte satisfies: 2.2 cP≤μ≤2.7 cP.

[0023] In a possible implementation, the volume energy density VED of the lithium-ion battery satisfies: VED ≥ 400Wh / L.

[0024] In one possible implementation, the lithium-ion battery includes a negative electrode plate, the negative electrode plate includes a negative electrode film layer; the single-side coating weight CW of the negative electrode film layer on the negative electrode plate satisfies: 0.06 mg / mm 2 ≤CW≤0.13mg / mm 2 .

[0025] In one possible implementation, 0.08 mg / mm 2 ≤CW≤0.115mg / mm 2 .

[0026] In one possible implementation, 0.09 mg / mm 2 ≤CW≤0.105mg / mm 2 .

[0027] In a possible implementation, the compaction density PD of the negative electrode film layer satisfies: 1.4 g / cc≤PD≤1.75 g / cc.

[0028] In one possible implementation, 1.55 g / cc ≤ PD ≤ 1.7 g / cc.

[0029] In one possible implementation, 1.4 g / cc ≤ PD ≤ 1.6 g / cc.

[0030] In one possible implementation, the lithium-ion battery includes a positive electrode plate, the positive electrode plate includes a positive electrode film layer; the single-side coating weight CW' of the positive electrode film layer on the positive electrode plate satisfies: 0.13 mg / mm 2 ≤CW'≤0.29mg / mm 2 .

[0031] In one possible implementation, 0.19 mg / mm 2≤CW'≤0.26mg / mm 2 .

[0032] In one possible implementation, 0.20 mg / mm 2 ≤CW'≤0.24mg / mm 2 .

[0033] In a possible implementation, the positive electrode film layer compaction density PD' satisfies: 2.5 g / cc≤PD'≤2.9 g / cc.

[0034] In one possible implementation, 2.6 g / cc≤PD'≤2.8 g / cc.

[0035] In one possible implementation, 2.7 g / cc≤PD'≤2.8 g / cc.

[0036] In a possible implementation, the filling coefficient a of the lithium-ion battery satisfies: 2.4 g / Ah≤a≤3.2 g / Ah.

[0037] In a possible implementation, in the direction of gravity, the height h of the positive electrode film layer and / or the negative electrode film layer satisfies: 70 mm ≤ h ≤ 110 mm.

[0038] In a second aspect, an electrical device is provided, wherein the electrical device includes the lithium-ion battery in any possible implementation of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0040] FIG1 is a schematic diagram of a battery cell.

[0041] FIG2 is a schematic diagram of a battery module.

[0042] FIG3 is a schematic diagram of a battery.

[0043] FIG4 is another schematic diagram of a battery. DETAILED DESCRIPTION

[0044] Below, the embodiments of the lithium-ion battery and the electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0045] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] In the description of this application, it should be noted that, unless otherwise specified, "plurality" means more than two; terms such as "upper," "lower," "left," "right," "inner," and "outer" indicating directions or positional relationships are merely for the purpose of facilitating the description of this application and simplifying the description, and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting this application. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0047] Unless otherwise specified, in this application, the phrase "A and / or B" means "A, B, or both A and B". More specifically, the condition "A and / or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0048] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0049] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0050] Unless otherwise specified, the following terms have the following meanings. Any undefined terms have their generally accepted meanings in the art.

[0051] Next, embodiments of the present application are introduced.

[0052] In recent years, secondary batteries have been widely used in power tools, electronic products, electric vehicles, aerospace and other fields due to their high energy density and long service life, and have thus achieved great development. Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the charge and discharge process of the battery, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. Among them, the electrolyte plays the role of conducting active ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, which allows active ions to pass through while preventing the positive and negative electrodes from short-circuiting, so that the electrochemical reaction of the secondary battery proceeds normally.

[0053] Take lithium-ion batteries, for example. They are a typical secondary battery. Because they rely on the chemical reaction of lithium ions intercalating and deintercalating between the positive and negative electrodes for charging and discharging, they are also called rocking-chair batteries. During the charging process, lithium ions are released from the positive electrode active material, transferred through the electrolyte to the negative electrode, and then embedded in the negative electrode active material. During the discharge process, lithium ions are released from the negative electrode active material, transferred through the electrolyte to the positive electrode, and then embedded in the positive electrode active material.

[0054] It should be understood that the "lithium insertion" and "intercalation" processes described in this application refer to the process in which lithium ions are embedded in the positive electrode active material or the negative electrode active material due to an electrochemical reaction, and the "de-lithiumization", "de-lithiumization" and "de-intercalation" processes described in this application refer to the process in which lithium ions are removed from the positive electrode active material or the negative electrode active material due to an electrochemical reaction.

[0055] As the application scope of lithium-ion batteries becomes wider and wider, and the usage scenarios become more and more diverse, new demands are being placed on the charging capacity of lithium-ion batteries. For example, for electric vehicles, range anxiety and long charging times have become major issues hindering their development. Therefore, fast charging (FC) capability is called an important goal for the development of lithium-ion batteries. Fast charging, abbreviated as fast charging, refers to charging the battery to a full or nearly full state in a relatively short period of time. The industry in different regions has different standards for the specific definition of fast charging. Generally speaking, a battery that can be charged to 80% of its full capacity in 0.5h to 2h is considered fast charging. Furthermore, a charging time of less than 10min can be considered to be in the range of extreme fast charging (XFC). However, studies have shown that low temperatures and high-rate charging can cause rapid degradation of battery performance such as capacity and output power. Therefore, in addition to meeting the requirements of fast charging, fast-charging batteries must also achieve a certain cycle life and meet relevant safety and electrical performance requirements. In the embodiments of the present application, fast-charging lithium-ion batteries refer to lithium-ion batteries with fast charging capabilities.

[0056] For lithium-ion batteries, concentration polarization is a major cause of increased internal resistance, decreased capacity, slower charging speed, and cycle drop. Concentration polarization is the result of the combined effects of multiple factors within lithium-ion batteries. One of the reasons is that the uneven distribution of lithium ion concentration in the electrolyte leads to inconsistent electrolyte conductivity at different locations within the lithium-ion battery. For example, during charging, the active material in the thickness direction of the positive and negative electrodes will undergo ion diffusion due to electrochemical reactions and other reasons, which inherently has a certain concentration difference. In the thickness direction of the positive and negative electrodes, the degree of electrolyte infiltration is also different, which further increases the difference in lithium ion concentration and exacerbates concentration polarization in the thickness direction of the positive and negative electrodes. For another example, during actual use, lithium-ion batteries will be fixed and placed, so due to the influence of gravity, the lithium ion concentration distribution in the electrolyte is also uneven. In other words, the "lower" the position along the gravity direction, the greater the lithium ion concentration, resulting in concentration polarization of the lithium-ion battery in the gravity direction.

[0057] For fast-charging lithium-ion batteries, under conditions of high current density or high-rate charging, concentration polarization is more serious than that of ordinary lithium-ion batteries, and there is a cycle accumulation phenomenon, which causes the capacity of fast-charging lithium-ion batteries to decay rapidly and drop in cycles, seriously affecting the practical application of fast-charging lithium-ion batteries.

[0058] There are multiple factors that contribute to concentration polarization in the gravity direction of lithium-ion batteries. For example, the filling coefficient of a lithium-ion battery affects concentration polarization in the gravity direction. The smaller the filling coefficient, the greater the concentration polarization in the gravity direction. This may be due to the following: the smaller the filling coefficient, the lower the electrolyte level inside the lithium-ion battery, the greater the electrolyte "climbing" height, resulting in significant differences in the degree of electrolyte wetting of the electrode sheets in the gravity direction. For electrode assemblies not covered by electrolyte, the electrolyte needs to be wetting in the opposite direction of gravity through capillary action. Different filling coefficients result in different wetting difficulties for the positive and negative electrode sheets in the gravity direction, leading to different lithium ion concentration distributions. This, in turn, affects the concentration polarization in the gravity direction of the lithium-ion battery. For example, the filling coefficient of a lithium-ion battery can be in the range of 2.4g / Ah to 3.2g / Ah. For another example, the size of the positive and negative electrode sheets also affects concentration polarization in the gravity direction. Specifically, in the direction of gravity, the smaller the height of the film layer on the electrode, the smaller the concentration polarization. The possible reason is that: the smaller the height of the film layer, the less difficult it is for the electrolyte to wet the electrode. The electrolyte can wet the electrode more evenly, and the difference in lithium ion concentration distribution is small. The difference in the height of the film layer on the electrode will also make the wettability of the positive and negative electrode plates in the direction of gravity different, and thus make the lithium ion concentration distribution different. Thus, it affects the concentration polarization of the lithium-ion battery in the direction of gravity. For example, in the direction of gravity, the height of the film layer on the electrode can be in the range of 70mm-110mm, optionally in the range of 75mm-100mm. The height of the film layer on the electrode can be controlled by adjusting the coating width of the slurry during the preparation of the electrode.

[0059] In view of this, the embodiment of the present application provides a lithium-ion battery and an electrical device, wherein the lithium-ion battery has a fast charging capability of being charged from 10% SOC to 80% SOC in a time of less than or equal to 15 minutes, and the lithium-ion battery includes an electrolyte having a lithium salt concentration greater than or equal to 1 mol / L and a density ρ of 0.9 g / mL to 1.23 g / mL. The larger lithium salt concentration of the electrolyte can improve the concentration polarization in the thickness direction of the positive and negative electrode sheets of the lithium-ion battery during fast charging, and the lithium salt concentration also affects the density, viscosity and conductivity of the electrolyte, and the density, viscosity and conductivity of the electrolyte affect the lithium ion dynamics; while the smaller electrolyte density helps to improve the conductivity of the electrolyte to balance the effect of the lithium salt concentration on the lithium ion dynamics, and can improve the concentration polarization in the gravity direction of the lithium-ion battery during fast charging. Therefore, the lithium-ion battery not only has excellent fast charging performance, but also has good cycle performance.

[0060] It should be understood that the above fast charging capability refers to the fast charging capability of the lithium-ion battery at 25° C. to 35° C. During the fast charging process of the lithium-ion battery, the current density (or rate) is usually not constant, but varies.

[0061] In one possible implementation, the charging time of a lithium-ion battery from 10% SOC to 80% SOC is less than or equal to 15 minutes when the current density is greater than or equal to 2.8C. This current density is the equivalent current density of the lithium-ion battery during the process of charging from 10% SOC to 80% SOC. In other words, in the process of charging from 10% SOC to 80% SOC, the current density I may gradually decrease from greater than 2.8C to less than 2.8C. In this process, the lithium-ion battery may undergo a transition from constant current charging to constant voltage charging, and thus, the current density is not constant. For example: start charging the lithium-ion battery at room temperature of 25°C, charge from 10% SOC to 80% SOC, and the charging time is 10 minutes (equivalent current I≥4C). The charging process is as follows: initially at 5C from 10% SOC to 45% SOC, then at 4.6C from 45% SOC to 50% SOC, 4.3C from 50% SOC to 55% SOC, 3.9C from 55% SOC to 60% SOC, 3.6C from 60% SOC to 65% SOC, 3.3C from 65% SOC to 70% SOC, 3.1C from 70% SOC to 75% SOC, and 2.9C from 75% SOC to 80% SOC, and then charging ends. The charging time for the lithium-ion battery to charge from 0% SOC to 100% SOC at 1C is 60 minutes. Therefore, when it is measured that the charging time of the lithium-ion battery from 10% SOC to 80% SOC is 10 minutes, the equivalent current density of the process can be calculated as: [(80% SOC-10% SOC) / (100% SOC-0% SOC)]×[(1C×60min) / 10min]=4.2C.

[0062] If a lithium-ion battery is placed on a charging station for charging, the time it takes to charge from 0% SOC to 100% SOC can also be directly recorded. For example, if this time is around 15 minutes (with an error of no more than 1 minute), it is generally considered a 4C fast-charging battery. For another example, if this time is around 12 minutes (with an error of no more than 1 minute), it is generally considered a 5C fast-charging battery. For another example, if this time is around 10 minutes (with an error of no more than 1 minute), it is generally considered a 6C fast-charging battery.

[0063] When the vehicle is charging at a charging pile, the charging curve will be displayed on the charging pile system program (the charging curve may be seen on the charging pile display, on the mobile phone charging control APP, or in the battery monitoring background, etc.). For example, the horizontal axis is the charging time, and the vertical axis is the charging power and the SOC of the battery. The charging power and SOC of the battery at different times can be seen from the graph, and the charging time of 20% SOC-80% SOC or the charging time of 10% SOC-80% SOC can also be read from the graph. In this application, a charging time of less than 15 minutes from 10% SOC to 80% SOC is considered fast charging, and the battery used in the vehicle is a fast charging battery.

[0064] In addition, if the vehicle or battery manual states that the charging time for the battery from 10% SOC to 80% SOC is less than 15 minutes, it also belongs to the fast-charging battery mentioned in this application.

[0065] Typically, a lithium-ion battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. The lithium-ion battery provided in this application and its various components are described below.

[0066] First, a lithium-ion battery is provided. The lithium-ion battery includes an electrolyte, the electrolyte includes a lithium salt, the concentration c of the lithium salt in the electrolyte satisfies: c ≥ 1 mol / L; the density ρ of the electrolyte satisfies: 0.9 g / mL ≤ ρ ≤ 1.23 g / mL; and the charging time t of the lithium-ion battery from 10% SOC to 80% SOC satisfies: 8.8 min ≤ t ≤ 15 min.

[0067] During the fast charging process of lithium-ion batteries, there is severe concentration polarization of lithium ions in the thickness direction of the positive and negative electrode sheets and in the direction of gravity, which may cause lithium deposition locally on the negative electrode sheet of the lithium-ion battery in severe cases. In the embodiment of the present application, the lithium-ion battery has fast charging capability, and the lithium-ion battery includes an electrolyte with a relatively high lithium salt concentration and a relatively low density. A higher lithium salt density helps to increase the transfer rate of lithium ions in the electrolyte, and helps to diffuse lithium ions in the thickness direction of the positive and negative electrode sheets, thereby improving the concentration polarization in the thickness direction of the positive and negative electrode sheets; a smaller density makes the electrolyte "lighter", which can reduce the difficulty of lithium ions "climbing" in the direction of gravity, facilitates the electrolyte to infiltrate the positive and negative electrode sheets in the direction of gravity, and increases the lithium ion transfer rate in the direction of gravity. Therefore, the lithium-ion battery of the present application can obtain good cycle performance while meeting fast charging conditions.

[0068] It should be understood that the concentration c of the lithium salt and the density ρ of the electrolyte can be controlled by controlling the amount of lithium salt added when preparing the electrolyte, selecting a suitable solvent and controlling its ratio; the charging time t of the lithium-ion battery can be regulated by controlling the charging current of the lithium-ion battery.

[0069] In one embodiment, c≤1.8 mol / L; optionally 1.1 mol / L≤c≤1.6 mol / L.

[0070] For example, c can be 1.1mol / L, 1.15mol / L, 1.2mol / L, 1.25mol / L, 1.3mol / L, 1.35mol / L, 1.4mol / L, 1.45mol / L, 1.5mol / L, 1.55mol / L, 1.6mol / L, 1.65mol / L, 1.7mol / L, 1.75mol / L, 1.8mol / L, or its value is within the range obtained by combining any two of the above values.

[0071] If the lithium salt concentration in the electrolyte is too low, the improvement in concentration polarization will be limited. If the concentration is too high, the viscosity of the electrolyte will increase, affecting the migration rate of lithium ions in the electrolyte. Therefore, in this embodiment, by controlling the lithium salt concentration within the above range, it helps to improve lithium ion concentration polarization while also ensuring that the electrolyte has a relatively suitable viscosity.

[0072] In one embodiment, 0.9 g / mL≤ρ≤1.23 g / mL; alternatively, 1.105 g / mL≤ρ≤1.22 g / mL.

[0073] Specifically, p can be 0.9 g / mL, 0.92 g / mL, 0.94 g / mL, 0.96 g / mL, 0.98 g / mL, 1 g / mL, 1.02 g / mL, 1.04 g / mL, 1.06 g / mL, 1.08 g / mL, 1.1 g / mL, 1.12 g / mL, 1.14 g / mL, 1.16 g / mL, 1.18 g / mL, 1.2 g / mL, 1.22 g / mL, 1.23 g / mL, or a value within the range obtained by combining any two of the above values.

[0074] If the electrolyte density is too high, the electrolyte is relatively "heavy," making it difficult for the electrolyte to penetrate and reabsorb the positive and negative electrodes in the direction of gravity. During fast charging, the concentration difference of lithium ions in the direction of gravity is large, exacerbating concentration polarization in the direction of gravity and detrimental to the cycling performance of the lithium-ion battery. If the density is too low, the electrolyte volume is larger for the same mass, resulting in a decrease in the lithium-ion battery's filling coefficient (in g / Ah), which may result in insufficient electrolyte injection and a cycling drop. Therefore, this embodiment can further improve the cycling performance of the lithium-ion battery by controlling the electrolyte density within an appropriate range.

[0075] In one embodiment, 8.8 min ≤ t ≤ 10 min. In other words, the lithium-ion battery provided in this application also has the capability of supporting extremely fast charging within ten minutes or less.

[0076] In one embodiment, the electrolyte includes a first solvent, which is a carbonate solvent. Specifically, the first solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), and ethyl methyl carbonate (EMC). For another example, the first solvent may also include dimethyl carbonate (DMC), diethyl carbonate (DEC), etc.

[0077] The first solvent is a carbonate solvent with low viscosity, high dielectric constant and good electrochemical stability. The low viscosity is conducive to the rapid migration of lithium ions in the electrolyte, and can alleviate the concentration polarization caused by the mismatch between the migration rate of lithium ions in the electrolyte and the migration rate of lithium ions in the positive and negative electrode sheets; the high dielectric constant is conducive to increasing the solubility of lithium salts in the electrolyte, thereby helping to increase the concentration of lithium salts in the electrolyte; good electrochemical stability helps to increase the operating voltage range of lithium-ion batteries and has good compatibility with positive and negative electrodes. Therefore, in this embodiment, by selecting a carbonate solvent as the first solvent for a fast-charging lithium-ion battery, the solubility of the lithium salt can be increased and the viscosity of the electrolyte can be reduced, thereby improving the concentration polarization of the fast-charging lithium-ion battery and helping to improve its cycle performance.

[0078] In one embodiment, the electrolyte includes a second solvent, which is a carboxylate solvent. Specifically, the second solvent includes R1-COO-R2, wherein R1 and R2 independently include at least one of an alkyl group having 1 to 5 carbon atoms and a halogenated alkyl group having 1 to 5 carbon atoms.

[0079] For example, R1-COO-R2 can be methyl acetate (MA) or ethyl acetate (EA).

[0080] Carboxylate solvents have lower density and viscosity, and higher ionic conductivity. Lower density can help reduce the overall density of the electrolyte, thereby improving the concentration polarization of the fast-charge lithium-ion battery in the direction of gravity; lower viscosity and higher ionic conductivity are conducive to the rapid migration of lithium ions in the electrolyte, thereby improving concentration polarization. Therefore, in this embodiment, by selecting a carboxylate solvent as the second solvent of the fast-charge lithium-ion battery in combination with the first solvent, the density of the electrolyte can be reduced and the ionic conductivity of the electrolyte can be increased, thereby improving the concentration polarization of the fast-charge lithium-ion battery and helping to improve its cycle performance.

[0081] In one embodiment, the mass content X of the first solvent in the electrolyte satisfies: 20%≤X≤30%.

[0082] In one embodiment, the mass content Y of the second solvent in the electrolyte satisfies: 20%≤Y≤60%.

[0083] Therefore, by adjusting the ratio of the first solvent to the second solvent, the conductivity and density of the electrolyte can be indirectly controlled so that the conductivity and density of the electrolyte are within an appropriate range.

[0084] It should be understood that the electrolyte may include other solvents in addition to the first solvent and the second solvent, such as nitrile solvents, sulfone solvents, ionic liquids, and the like.

[0085] In one embodiment, the lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0086] In one embodiment, the lithium salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, and the concentration of the lithium bis(fluorosulfonyl)imide in the lithium salt of the electrolyte is less than or equal to 30%. The above concentration ratio is calculated by dividing the concentration of the lithium bis(fluorosulfonyl)imide in the electrolyte by the concentration of all lithium salts in the electrolyte.

[0087] Specifically, lithium bis(fluorosulfonyl)imide has a high solubility in carbonate solvents and has a higher electrical conductivity and lithium ion transference number than lithium hexafluorophosphate. Therefore, by selecting lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide as lithium salts, the solubility of lithium salts in the electrolyte comprising the aforementioned solvents can be further improved, so that the electrolyte has a higher lithium salt concentration, thereby improving concentration polarization. At the same time, considering that lithium bis(fluorosulfonyl)imide is corrosive to lithium foil, controlling the concentration ratio of lithium bis(fluorosulfonyl)imide can effectively inhibit its corrosion to the positive electrode sheet.

[0088] It should be understood that the concentration ratio of lithium bis(fluorosulfonyl)imide can be achieved by controlling the molar mass of the various lithium salts in the electrolyte. In addition, by adjusting the concentration of the lithium salt in the electrolyte, the conductivity and density of the electrolyte can also be adjusted.

[0089] In one embodiment, the conductivity σ of the electrolyte satisfies: 13 mS / cm≤σ≤20 mS / cm.

[0090] In one embodiment, the viscosity μ of the electrolyte satisfies: 2.2 cP≤μ≤2.7 cP.

[0091] In one embodiment, the lithium-ion battery includes a negative electrode plate, the negative electrode plate includes a negative electrode film layer; the negative electrode film layer has a single-side coating weight CW on the negative electrode plate that satisfies: 0.06 mg / mm 2 ≤CW≤0.13mg / mm 2; Optionally, 0.08 mg / mm 2 ≤CW≤0.11mg / mm 2 ; Optionally, 0.09 mg / mm 2 ≤CW≤0.105mg / mm 2 .

[0092] Specifically, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector. The coating weight CW is the coating weight per unit area on one surface of the negative electrode current collector.

[0093] In one embodiment, the compaction density PD of the negative electrode film layer satisfies: 1.4 g / cc≤PD≤1.75 g / cc; optionally, 1.5 g / cc≤PD≤1.65 g / cc; optionally, 1.4 g / cc≤PD≤1.6 g / cc.

[0094] Specifically, during the lithium-ion battery manufacturing process, the pole pieces undergo a rolling process to achieve a compaction density for the film layer, taking into account design parameters such as energy density. The compaction density of the film layer is closely related to factors such as the particle morphology, particle size distribution, and specific surface area of ​​the active material itself, as well as the ratio of the components in the coating slurry, coating weight, and current collector thickness. Compaction density is crucial for the capacity, rate capability, and cycling performance of lithium-ion batteries.

[0095] The compacted density of the film layer is PD = pole piece area density / (pole piece thickness - current collector thickness). The pole piece area density refers to the mass of the film layer per unit area.

[0096] In one embodiment, the lithium-ion battery includes a positive electrode plate, the positive electrode plate includes a positive electrode film layer; the single-side coating weight CW' of the positive electrode film layer on the positive electrode plate satisfies: 0.13 mg / mm 2 ≤CW'≤0.29mg / mm 2 ; Optionally, 0.19 mg / mm 2 ≤CW'≤0.26mg / mm 2 ; Optionally, 0.20 mg / mm 2 ≤CW'≤0.24mg / mm 2 .

[0097] In one embodiment, the compaction density PD' of the positive electrode film layer satisfies: 2.5 g / cc≤PD'≤2.9 g / cc; optionally, 2.6 g / cc≤PD'≤2.8 g / cc; optionally, 2.7 g / cc≤PD'≤2.8 g / cc.

[0098] In one embodiment, the volume energy density VED of the lithium-ion battery satisfies: VED ≥ 400Wh / L.

[0099] In other words, in addition to fast charging capability, the lithium-ion battery of the present application is also designed to have a high volumetric energy density. In other words, the fast-charging lithium-ion battery also has a high volumetric energy density and has a wide range of application prospects. The high volumetric energy density of the lithium-ion battery can be achieved by controlling the loading amount of its active material and the compaction density of the positive and negative electrode sheets.

[0100] For high-energy-density lithium-ion batteries, the active material loading on their positive and negative electrode plates is typically greater than that of ordinary lithium-ion batteries, resulting in thicker positive and negative electrode plates and more severe polarization in the thickness direction of the positive and negative electrode plates during fast charging. However, the lithium-ion battery provided in the embodiments of the present application can achieve fast charging capabilities and good cycling performance by controlling fast charging conditions and providing an electrolyte compatible with fast charging conditions.

[0101] Next, the positive electrode sheet, negative electrode sheet, separator and electrolyte in the above-mentioned fast-charging lithium-ion battery are introduced in detail.

[0102] [Electrolyte]

[0103] The above text has partially mentioned some properties of the electrolyte in the lithium-ion battery of this application. The electrolyte will be introduced in more detail below.

[0104] The electrolyte conducts ions between the positive and negative electrodes. It primarily consists of an electrolyte salt and a solvent. In lithium-ion batteries, the electrolyte salt is primarily lithium salt, and may also include other additives.

[0105] The selection of lithium salts has been introduced in the previous article and will not be repeated here.

[0106] In one embodiment, in addition to the examples mentioned above, the solvent may also include at least one of ethylene carbonate, propylene carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0107] As mentioned above, the mass content X of the first solvent in the electrolyte satisfies: 20%≤X≤30%, and the mass content Y of the second solvent in the electrolyte satisfies: 20%≤Y≤60%.

[0108] Specifically, X may be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or any combination thereof. Y may be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, or any combination thereof.

[0109] As mentioned above, the electrolyte conductivity σ satisfies: 13mS / cm≤σ≤20mS / cm. The electrolyte viscosity μ satisfies: 2.2cP≤μ≤2.7cP.

[0110] Specifically, σ can be 13 mS / cm, 14 mS / cm, 15 mS / cm, 16 mS / cm, 17 mS / cm, 18 mS / cm, 19 mS / cm, or 20 mS / cm, or any combination thereof. M can be 2.2 cP, 2.3 cP, 2.4 cP, 2.5 cP, 2.6 cP, or 2.7 cP, or any combination thereof. In this embodiment, the conductivity and viscosity of the electrolyte can be adjusted to meet the above ranges by selecting the solvent and lithium salt, and controlling the lithium salt concentration and solvent ratio.

[0111] In one embodiment, the electrolyte also includes additives, which may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0112] [Negative electrode]

[0113] The negative electrode sheet generally includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material.

[0114] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0115] In one embodiment, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0116] In one embodiment, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0117] As mentioned above, the single-sided coating weight CW of the negative electrode film on the negative electrode sheet meets the following requirements: 0.06 mg / mm 2 ≤CW≤0.13mg / mm 2 ; Optionally, 0.08 mg / mm 2 ≤CW≤0.11mg / mm 2 The compaction density PD of the negative electrode sheet satisfies: 1.4 g / cc ≤ PD ≤ 1.75 g / cc; optionally, 1.5 g / cc ≤ PD ≤ 1.65 g / cc.

[0118] Specifically, CW can be 0.06 mg / mm 2 , 0.07mg / mm 2 , 0.08mg / mm 2 , 0.09mg / mm 2 , 0.1mg / mm 2 , 0.11mg / mm 2 , 0.12mg / mm 2 , 0.13mg / mm 2 , or a value within the range obtained by combining any two of the above values. PD can be 1.4 g / cc, 1.45 g / cc, 1.5 g / cc, 1.55 g / cc, 1.6 g / cc, 1.65 g / cc, 1.7 g / cc, 1.75 g / cc, or a value within the range obtained by combining any two of the above values.

[0119] In the introduction to lithium-ion batteries, lithium-ion batteries not only have fast charging capabilities but also high volumetric energy density. Therefore, the coating weight of the negative electrode film layer must meet the above range to ensure that the lithium-ion battery has the corresponding volumetric energy density. Furthermore, considering that a larger coating weight may result in a thicker negative electrode film layer, the thickness of the negative electrode film has a certain impact on the fast charging capability of the lithium-ion battery. The reason is that the smaller the thickness of the negative electrode film layer, the more conducive it is to electrolyte diffusion and infiltration, which can reduce concentration polarization along the thickness direction of the negative electrode plate, reduce the risk of lithium deposition during high-current charging, and improve the charging capacity of the lithium-ion battery. Therefore, the compaction density of the negative electrode plate is designed to meet the above range. This is because the fast charging capability of the lithium-ion battery is not only affected by the thickness of the negative electrode film layer, but also by the porosity. Generally speaking, the smaller the compaction density of the negative electrode plate, the greater the porosity of the negative electrode film layer, which is more conducive to electrolyte diffusion and infiltration, and the smaller the concentration polarization, the better the charging capacity of the lithium-ion battery. Therefore, when the coating weight of the negative electrode film is high, controlling the compaction density of the negative electrode sheet within an appropriate range can control the porosity of the negative electrode film. Paired with the electrolyte with a high lithium salt concentration and low density mentioned above, fast-charging lithium-ion batteries can achieve good cycle performance and high volumetric energy density.

[0120] When the negative electrode film layer is controlled to meet the above-mentioned thickness and load, it is equivalent to taking into account the porosity and thickness of the negative electrode film layer at the same time, which can enable the lithium-ion battery to have both better charging capacity and energy density.

[0121] In one embodiment, the negative electrode film layer further includes a binder. The binder can be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0122] In one embodiment, the negative electrode film layer further includes a conductive agent, which can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0123] In one embodiment, the negative electrode film layer further includes other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0124] In one embodiment, the negative electrode sheet can be prepared by forming a negative electrode slurry using the aforementioned components for preparing the negative electrode sheet. For example, the negative electrode active material, conductive agent, binder, and any other components are dispersed in a solvent (e.g., N-methylpyrrolidone) to form the negative electrode slurry. The negative electrode slurry is then coated onto the negative electrode current collector. After drying and cold pressing, the negative electrode sheet is obtained.

[0125] [Positive electrode]

[0126] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0127] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0128] In one embodiment, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0129] In one embodiment, the positive electrode active material may adopt the positive electrode active material for batteries that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM622), LiNi 0.8 Co 0.1 Mn0.1 O2 (also referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.1 Al 0.05 O2) and at least one of its modified compounds. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and at least one of a composite material of lithium iron manganese phosphate and carbon. The battery will be accompanied by the deintercalation and consumption of Li during the charging and discharging process, and the molar content of Li in the positive electrode active material is different when the battery is discharged to different states. In the enumeration of positive electrode active materials in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li will change after the charge and discharge cycle. In the enumeration of positive electrode active materials in this application, the molar content of O is only an ideal state value. The release of lattice oxygen will cause the molar content of O to change, and the actual molar content of O will fluctuate.

[0130] As mentioned above, the single-sided coating weight CW' of the positive electrode film on the positive electrode sheet meets the following requirements: 0.13 mg / mm 2 ≤CW'≤0.29mg / mm 2 ; Optionally, 0.19 mg / mm 2 ≤CW'≤0.26mg / mm 2 The compaction density PD' of the positive electrode sheet satisfies: 2.5 g / cc ≤ PD' ≤ 2.9 g / cc; optionally, 2.6 g / cc ≤ PD' ≤ 2.8 g / cc.

[0131] Specifically, CW' can be 0.13 mg / mm 2 , 0.14mg / mm 2 , 0.15mg / mm 2 , 0.16mg / mm 2 , 0.17mg / mm 2 , 0.18mg / mm 2 , 0.19mg / mm 2 , 0.20mg / mm 2 , 0.21mg / mm 2 , 0.22mg / mm 2 , 0.23mg / mm 2 , 0.24mg / mm 2 , 0.25mg / mm 2 , 0.26mg / mm 2 , 0.27mg / mm 2, 0.28mg / mm 2 , 0.29mg / mm 2 , or its value is within the range obtained by combining any two of the above values. PD' can be 2.5 g / cc, 2.55 g / cc, 2.6 g / cc, 2.65 g / cc, 2.7 g / cc, 2.75 g / cc, 2.8 g / cc, 2.85 g / cc, 2.9 g / cc, or its value is within the range obtained by combining any two of the above values.

[0132] In one embodiment, the positive electrode film layer further includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0133] In one embodiment, the positive electrode film layer further includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0134] In one embodiment, the positive electrode sheet can be prepared by separately forming a positive electrode slurry from the components used to prepare the positive electrode sheet. For example, the first positive electrode active material and / or the second positive electrode active material, a conductive agent, a binder, and any other components are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is then coated on a positive electrode current collector. After drying and cold pressing, the positive electrode sheet can be obtained.

[0135] [Isolator]

[0136] In one embodiment, the battery further includes a separator. The present application has no particular limitation on the type of separator. For example, any known porous structure separator with good chemical and mechanical stability can be selected.

[0137] In one embodiment, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0138] In one embodiment, the negative electrode sheet, the positive electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0139] In one embodiment, the battery cell may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0140] In one embodiment, the outer packaging of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery cell can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0141] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square, or any other shape. For example, FIG1 shows a battery cell 100 having a square structure as an example.

[0142] It should be understood that the battery cell 100 may be the lithium-ion battery in the aforementioned embodiment.

[0143] Figure 2 shows an example battery module 200. Referring to Figure 2 , in the battery module 200, multiple battery cells 100 may be arranged sequentially along the length of the battery module 200. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 100 may be secured by fasteners. The multiple battery cells 100 may be of the same chemical system or of different chemical systems.

[0144] Optionally, in one embodiment, the battery module 200 may further include a housing having an accommodation space, and the plurality of battery cells 100 may be accommodated in the accommodation space.

[0145] Optionally, in one embodiment, the battery modules 200 may be assembled into a battery. The battery may contain one or more battery modules 200. The specific number may be selected by those skilled in the art according to the application and capacity of the battery.

[0146] Figures 3 and 4 illustrate an example battery pack 300. Referring to Figures 3 and 4, the battery pack 300 may include a battery box and multiple battery modules 200 disposed within the battery box. The battery box includes an upper case 301 and a lower case 302. The upper case 301 can be placed over the lower case 302 to form an enclosed space for accommodating the battery modules 200. The multiple battery modules 200 can be arranged in any manner within the battery box.

[0147] It should be understood that the battery cells 100 can first be assembled into the battery module 200, and the battery pack 300 can be assembled from the battery module 200. Alternatively, the battery pack 300 can be directly assembled from the battery cells 100, omitting the intermediate form of the battery module 200.

[0148] In addition, the present application also provides an electrical device, which includes the lithium-ion battery in the aforementioned embodiment.

[0149] In another embodiment, an electrical device includes at least one of the battery cell 100, battery module 200, or battery pack 300 provided herein. The battery cell 100, battery module 200, or battery pack 300 can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0150] As an electric device, the number of battery cells 100 , battery modules 200 , or battery packs 300 can be selected according to its usage requirements.

[0151] As an example of an electric device, the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the electric device's requirements for high power and high energy density of secondary batteries, a battery pack or battery module can be used.

[0152] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is generally required to be lightweight and thin, and may use a secondary battery as a power source.

[0153] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0154] [Examples 1-14 and Comparative Examples 1-2]

[0155] Example 1

[0156] (1) Preparation of negative electrode sheet

[0157] The negative electrode active material, artificial graphite, the conductive agent, acetylene black, the binder, styrene-butadiene rubber, and the thickener, sodium carboxymethyl cellulose, were dissolved in deionized water at a mass ratio of 96:0.5:2.5:1 and mixed thoroughly to produce a negative electrode slurry. The slurry was then evenly coated onto the negative electrode current collector copper foil. The negative electrode sheet was then dried, rolled, and slit. The coating weight of the negative electrode film on the negative electrode sheet was CW = 0.104 mg / mm. 2 , the compaction density of the negative electrode sheet PD = 1.6g / cc.

[0158] (2) Preparation of positive electrode sheet

[0159] The positive electrode active material, lithium iron phosphate, the binder polyvinylidene fluoride, and the conductive agent acetylene black were dissolved in the solvent N-methylpyrrolidone at a mass ratio of 97:2:1 and mixed thoroughly to obtain a positive electrode slurry. The positive electrode slurry was then evenly coated on the positive electrode current collector aluminum foil. After drying, rolling, and slitting, the positive electrode sheet was obtained. The coating weight of the positive electrode film on the positive electrode sheet was CW' = 0.23 mg / mm. 2 , the powder compaction density of the positive electrode sheet PD'=2.7g / cc.

[0160] (3) Preparation of electrolyte

[0161] An electrolyte was prepared in an argon atmosphere glove box with a water content of less than 10 ppm. The specific process was as follows: a first solvent, ethylene carbonate (EC), a second solvent (EA), and dimethyl carbonate (DMC) were mixed uniformly in a mass ratio of 30:40:30, and then an appropriate amount of lithium hexafluorophosphate (LiPF6) was slowly added thereto and stirred thoroughly until completely dissolved. The lithium salt concentration in the electrolyte was c = 1.3 mol / L, the density of the electrolyte was ρ = 1.171 g / mL, the mass content of the first solvent in the electrolyte was X = 30%, and the mass content of the second solvent in the electrolyte was Y = 40%. The electrolyte of Example 1 was measured to have a conductivity σ = 17.1 mS / cm and a viscosity μ = 2.54 cP.

[0162] (4) Preparation of lithium-ion batteries

[0163] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order so that the separator is located between the positive electrode sheet and the negative electrode sheet and can isolate the positive electrode sheet from the negative electrode sheet; then the stacked components are wound and placed in a square aluminum shell, and after drying, the electrolyte is injected. After packaging, standing, and formation, the lithium-ion battery of Example 1 is obtained.

[0164] The volume energy density VED of the lithium-ion battery of Example 1 was measured to be 415Wh / L. It can be seen that the lithium-ion battery is a lithium-ion battery with high energy density. For this lithium-ion battery, the charging time can be designed by performing a rate test on the lithium-ion battery. The specific process is: remove the positive and negative pole pieces of the lithium-ion battery in Example 1, soak and clean them with DMC solvent for more than 72 hours, wait until the solvent, lithium salt and additives of the electrolyte are completely leached, dry the pole pieces in a vacuum oven, and then assemble the positive and negative pole pieces into a laminated three-electrode battery cell, in which the copper wire is used as the reference electrode. Set a series of different charge rates, charge the laminated three-electrode battery cell at different charge rates at 25°C, and cut off the reference electrode potential at each charge rate when it drops to 0mV. Thus, the SOC corresponding to different charge rates can be measured. If charging continues when the reference electrode potential drops below 0mV, the battery will undergo lithium plating and cannot be used subsequently. Therefore, the different SOCs obtained by the above method mean that the charge rate corresponding to the SOC is the maximum charge rate of the lithium-ion battery at the SOC. According to the data fitting of the maximum charge rate corresponding to different SOCs, a relationship curve between SOC and maximum charge rate can be obtained. For example, the above method can be used to take 5% SOC as a point and correspond to a maximum charge rate at the SOC, such as 5% SOC, 10% SOC, 15% SOC to 100% SOC. According to these data, the relationship curve between the two can be fitted to obtain the maximum charge rate with the largest value from 10% SOC to 80% SOC. In the actual charging process, for reasons of battery safety, service life and other factors, the maximum charge rate will not be used directly for charging, but the maximum charge rate multiplied by 0.8 will be used as the charge rate in actual use. Therefore, the equivalent current density of the lithium-ion battery of Example 1 charged from 10% SOC to 80% SOC can be considered to be 0.8 multiplied by the maximum charge rate with the largest value.

[0165] As mentioned above, when estimating the equivalent current density from the charging time, the charging time for lithium-ion batteries at 1C from 0% SOC to 100% SOC is 60 minutes. Therefore, based on the proportional relationship between the equivalent current density and the charging time, the charging time of the lithium-ion battery of Example 1 can also be estimated.

[0166] Based on the above test and derivation process, the fast charging capability of the lithium-ion battery of Example 1 is: the charging time from 10% SOC to 80% SOC is t=11.6 min.

[0167] The lithium-ion battery of Example 1 was placed on a charging station and its charging time from 10% SOC to 80% SOC was tested (see the test method below). The measured t was approximately 11.6 minutes (with an error of less than 1 minute). Table 1 shows this as approximately 11.6 minutes, i.e., "~11.6".

[0168] Example 2

[0169] Compared to Example 1, in the lithium-ion battery of Example 2, c = 1.0 mol / L, ρ = 1.138 g / mL, σ = 16.5 mS / cm, and μ = 2.36 cP. A charging time test of the lithium-ion battery of Example 2 showed that t was also around 11.6 minutes (with an error of less than 1 minute). In other words, the lithium-ion battery of Example 2 is also a fast-charging lithium-ion battery.

[0170] Example 3

[0171] Compared with Example 1, in the lithium-ion battery of Example 3, c = 1.2 mol / L, ρ = 1.152 g / mL, σ = 16.7 mS / cm, and μ = 2.41 cP. Similar to Example 2, the lithium-ion battery of Example 3 also has a t of approximately 11.6 min, indicating a fast-charging lithium-ion battery.

[0172] Example 4

[0173] Compared with Example 1, in the lithium ion battery of Example 4, c = 1.6 mol / L, ρ = 1.203 g / mL, σ = 17.0 mS / cm, and μ = 2.68 cP. The lithium ion battery of Example 4 also has a t of approximately 11.6 min, indicating a fast-charging lithium ion battery.

[0174] Example 5

[0175] Compared with Example 1, in the lithium-ion battery of Example 5, c = 1.8 mol / L, ρ = 1.23 g / mL, t = XX min, σ = 16.3 mS / cm, and μ = 2.75 cP. The lithium-ion battery of Example 5 also has a t of approximately 11.6 min, indicating a fast-charging lithium-ion battery.

[0176] Example 6

[0177] Compared to Example 1, in the lithium-ion battery of Example 6, the first solvent was a mixture of EMC and EC in a volume ratio of 2:8, and the second solvent was MA, with ρ = 1.165 g / mL, σ = 17.0 mS / cm, and μ = 2.48 cP. The lithium-ion battery of Example 6 also had a t of approximately 11.6 min, indicating a fast-charging lithium-ion battery.

[0178] Example 7

[0179] Compared with Example 1, in the lithium-ion battery of Example 7, X = 20%, ρ = 1.167 g / mL, σ = 16.8 mS / cm, and μ = 2.49 cP. The lithium-ion battery of Example 7 also has a t of approximately 11.6 min, indicating a fast-charging lithium-ion battery.

[0180] Example 8

[0181] Compared with Example 1, in the lithium-ion battery of Example 8, X = 25%, ρ = 1.169 g / mL, σ = 17.0 mS / cm, and μ = 2.52 cP. The lithium-ion battery of Example 8 also has a t of approximately 11.6 min, indicating a fast-charging lithium-ion battery.

[0182] Example 9

[0183] Compared to Example 1, in the lithium-ion battery of Example 9, Y = 20%, ρ = 1.182 g / mL, σ = 16.0 mS / cm, and μ = 2.43 cP. A rate test was performed on the lithium-ion battery of Example 9 with reference to Example 1, and t was calculated to be 12.9 min. A charge time test was performed on the lithium-ion battery of Example 9, and t was measured to be approximately 12.9 min (with an error of less than 1 min).

[0184] Example 10

[0185] Compared to Example 1, in the lithium-ion battery of Example 10, Y = 60%, ρ = 1.169 g / mL, σ = 17.9 mS / cm, and μ = 2.38 cP. A rate test was performed on the lithium-ion battery of Example 10 with reference to Example 1, and t was calculated to be 10.2 min. A charging time test was performed on the lithium-ion battery of Example 10, and t was measured to be approximately 10.2 min (with an error of less than 1 min).

[0186] Example 11

[0187] Compared with Example 1, the lithium salt in the lithium-ion battery of Example 11 includes LiPF6 and lithium bis(fluorosulfonyl)imide (LiFSI). The concentration of the lithium salt in the electrolyte remains at 1.3 mol / L, of which the concentration of LiPF6 is 0.91 mol / L and the concentration of LiFSI is 0.39 mol / L, with the LiFSI concentration accounting for 30%; ρ = 1.17 g / mL, σ = 17.3 mS / cm, and μ = 2.54 cP. The lithium-ion battery of Example 11 also has a t of approximately 11.6 min, indicating a fast-charging lithium-ion battery.

[0188] Example 12

[0189] Compared to Example 11, the lithium-ion battery of Example 12 has a LiPF6 concentration of 1.17 mol / L and a LiFSI concentration of 0.13 mol / L, with the LiFSI concentration accounting for 10%; ρ = 1.17 g / mL, σ = 17.1 mS / cm, and μ = 2.54 cP. The lithium-ion battery of Example 12 also has a t of approximately 11.6 min, indicating a fast-charging lithium-ion battery.

[0190] Example 13

[0191] Compared to Example 11, the lithium-ion battery of Example 13 has a LiPF6 concentration of 0.65 mol / L and a LiFSI concentration of 0.65 mol / L, with the LiFSI concentration accounting for 50%; ρ = 1.17 g / mL, σ = 17.6 mS / cm, and μ = 2.53 cP. The lithium-ion battery of Example 13 also has a t of approximately 11.6 min, indicating a fast-charging lithium-ion battery.

[0192] Example 14

[0193] Compared with Example 1, in the lithium ion battery of Example 14, c = 1.3 mol / L, X = 20%, Y = 60%, ρ = 1.165 g / mL, σ = 18.3 mS / cm, μ = 2.33 cP. In Example 14, by adjusting the coating surface density, compaction density and other parameters of the positive and negative electrode sheets, a lithium ion battery with a volume energy density VED = 406 Wh / L was prepared. Changes in parameters such as coating surface density and compaction density have an impact on the charging capacity of the lithium ion battery. Therefore, with reference to Example 1, the lithium ion battery of Example 14 was subjected to a rate test, and it was calculated that t = 8.8 min. The lithium ion battery of Example 14 was subjected to a charging time test, and t was measured to be around 8.8 min (the error was less than 1 min).

[0194] Comparative Example 1

[0195] Compared with Example 1, in the lithium ion battery of Comparative Example 1, c = 0.8 mol / L, ρ = 1.21 g / mL, σ = 15.7 mS / cm, and μ = 2.21 cP. The lithium ion battery of Comparative Example 1 also has a t of approximately 11.6 min, indicating a fast-charging lithium ion battery.

[0196] Comparative Example 2

[0197] Compared to Example 1, the lithium-ion battery of Comparative Example 2 had c = 1.9 mol / L, ρ = 1.242 g / mL, σ = 16 mS / cm, and μ = 2.8 cP. The lithium-ion battery of Comparative Example 2 also had a t of approximately 11.6 min, indicating a fast-charging lithium-ion battery. Product parameters for Examples 1-14 and Comparative Examples 1-2.

[0198] Table 1: Product parameters of Examples 1-14 and Comparative Examples 1-2

[0199] In Table 1, "lithium salt" represents the type of lithium salt in the lithium-ion battery electrolyte, and "c" represents the concentration of lithium salt in the electrolyte. "First solvent" represents the type of the first solvent in the electrolyte, "second solvent" represents the type of the second solvent in the electrolyte, "X" represents the mass content of the first solvent in the electrolyte, "Y" represents the mass content of the second solvent in the electrolyte, "ρ" represents the density of the electrolyte in the lithium-ion battery, "fast charge time" represents the fast charge time measured by the charging time test of the lithium-ion battery, and "number of cycles" represents the number of cycles of the lithium-ion battery at 25°C to 80% SOH (it is generally believed that the battery capacity is consumed to 80% of the rated capacity and the SOH of the battery is 80% SOH).

[0200] Through the analysis and comparison of Examples 1-14 and Comparative Examples 1-2, it can be seen that the cycle performance of Examples 1-14 is significantly better than that of Comparative Examples 1-2, indicating that the use of an electrolyte with high lithium salt concentration and low density in a lithium-ion battery that supports high-current fast charging can effectively improve the concentration polarization during the fast charging process of the lithium-ion battery and enhance the cycle performance of the lithium-ion battery.

[0201] According to the comparative analysis of the data of Examples 1-5 and Comparative Example 2, it can be seen that as the concentration of lithium salt in the electrolyte increases, the density and viscosity of the electrolyte increase accordingly. In the range of lithium salt concentration of 1.1 mol / L to 1.6 mol / L, the conductivity of the electrolyte experiences a trend of first increasing and then decreasing. The cycle performance of the lithium-ion batteries of Examples 1-4 improves with the increase of lithium salt concentration. However, the cycle performance of Comparative Example 2, which has the highest lithium salt concentration, is far inferior to that of Examples 1-5, and the cycle performance of Example 5 is also inferior to that of Example 4. Therefore, it is shown that increasing the concentration of lithium salt in the electrolyte can effectively improve concentration polarization and improve the cycle performance of lithium-ion batteries. However, too high a lithium salt concentration will affect the density, viscosity and conductivity of the electrolyte, and the density, viscosity and conductivity of the electrolyte will affect the dynamics of the lithium-ion battery and will also affect the cycle performance of the lithium-ion battery. Therefore, taking all factors into consideration, it is more conducive to improving the cycle performance of the lithium-ion battery by controlling the lithium salt concentration within a higher and appropriate range. It should be understood that when the electrolyte density is large, it will be more difficult for lithium ions to "climb" in the direction of gravity, exacerbating the concentration polarization in the direction of gravity. When the electrolyte density is small, the concentration polarization in the direction of gravity is small. Based on this, although the density data of the electrolyte provided in the data of Table 1 are all large, the solution of the present application can improve the concentration polarization when the electrolyte density is large, and improve the cycle performance of the lithium-ion battery. Then, when the electrolyte density is small and the concentration polarization is small, it can be inferred without a doubt that the solution of the present application can also improve the concentration polarization and improve the cycle performance of the lithium-ion battery.

[0202] The data of Examples 1 and 6 show that different first solvents and second solvents can achieve similar effects when the lithium salt concentration is the same.

[0203] According to the comparative analysis of the data of Examples 1, 7-8, it can be seen that as the mass content of the first solvent increases, the conductivity of the electrolyte also increases, the lithium ion dynamics improve, and the cycle performance improves accordingly. At the same time, the viscosity and density of the electrolyte also increase. It can be seen that with the same 5% increase in mass content, the cycle performance of Example 8 is improved by 238 cycles compared to Example 7, while the cycle performance of Example 1 is only improved by 48 cycles compared to Example 8. This shows that the concentration polarization caused by the increase in electrolyte viscosity and density is aggravated. This proves that by controlling the mass content of the first solvent within an appropriate range, it helps to improve the cycle performance of lithium-ion batteries.

[0204] According to the data analysis and comparison of Examples 1, 9-10, it can be seen that as the mass content of the second solvent increases, the density of the electrolyte decreases and the conductivity increases. It is proved that the second solvent can reduce the density of the electrolyte and improve the conductivity of the electrolyte. At the same time, the cycle performance of the lithium-ion battery is also improved, but the improvement trend is also gradually slowing down. It shows that on the basis of the mass content of the first solvent being within a suitable range, by controlling the mass content of the second solvent within a suitable range, it is helpful to improve the cycle performance of the lithium-ion battery. In other words, by adjusting the ratio of the first solvent to the second solvent, the conductivity and density of the electrolyte can be indirectly regulated so that the conductivity and density of the electrolyte are within a suitable range, thereby comprehensively improving the cycle performance of the lithium-ion battery.

[0205] In addition, although the cycle performance is not as good as that of Example 1, the charging time of the lithium-ion batteries of Examples 9-10 is further shortened, indicating that the content of the second solvent improves the lithium ion kinetics and contributes to the fast charging performance of the lithium-ion battery.

[0206] According to the data analysis and comparison of Examples 11-13, when using lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, the cycle performance of the lithium-ion battery is further improved as the concentration of lithium bis(fluorosulfonyl)imide increases. At the same time, considering the corrosiveness of lithium bis(fluorosulfonyl)imide, and according to the data of Examples 11 and 13, the cycle performance is improved but the trend is significantly slowed down. This shows that by controlling the concentration ratio of lithium bis(fluorosulfonyl)imide within an appropriate range, the cycle performance of the lithium-ion battery can be further improved.

[0207] Example 14 demonstrates another energy-density lithium-ion battery, which, when used with an electrolyte similar to that in the previous examples, achieves a shorter charging time and excellent cycle performance.

[0208] The following is a brief introduction to the test methods for the physical and chemical parameters and performance parameters involved in the embodiments of this application. It should be understood that the following test methods are only examples, and other test methods known in the art can also be used for testing.

[0209] 1. Test method for electrolyte conductivity

[0210] The test method is in accordance with HG / T 4067-2015. The conductivity of the electrolyte to be tested is tested using a conductivity meter: about 100 ml of the sample to be tested is taken into a dry, clean, corrosion-resistant sample bottle, and sealed in a constant temperature water bath at 25±0.5℃. When the temperature of the sample to be tested is constant, the sample bottle cap is replaced with a rubber stopper with an electrode inserted. When the temperature is within the range of 25±0.5℃, the data is read, which is the conductivity of the sample to be tested.

[0211] 2. Molar concentration test method

[0212] The molar concentration of the lithium salt in the electrolyte can be determined by various methods known to those skilled in the art, such as titration, electrochemical analysis, spectrophotometry, and inductively coupled plasma analysis.

[0213] 3. Charging time test method

[0214] Place the lithium-ion battery to be tested on a charging pile, adjust the state of charge of the lithium-ion battery to 10% SOC (the capacity is 10% of the rated capacity), and then charge it on the charging pile. Record the time it takes for the lithium-ion battery to charge to 80% SOC (80% of the rated capacity), that is, the charging time of the lithium-ion battery.

[0215] 4. Volume energy density test method

[0216] Place the lithium-ion battery at 25°C, charge it to 3.8V at a constant current of 0.33C, let it rest for 1 minute, then charge it to 3.8V at a constant current of 0.1C and let it rest for 30 minutes. Discharge it to 2.0V at a constant current of 0.33C, and record the discharge capacity A0 at this time in Ah. Use calipers to measure the length, width, and height of the lithium-ion battery and calculate the volume of the single cell V0 in L. The volume energy density of the single cell VED = (A0 × discharge platform voltage of the lithium-ion battery) / V0, in Wh / L. It should be understood that lithium-ion batteries with different positive and negative electrode systems have different discharge platform voltages, which can be obtained by testing their charge and discharge curves or referring to existing literature.

[0217] 5. Coating weight test method

[0218] Cut the negative electrode sheet to a specified area S and weigh it to obtain the weight m1. Wash away the film layer on the surface of the negative electrode current collector and weigh the weight m2 of the negative electrode current collector. The loading amount of the negative electrode film layer on the negative electrode current collector is (m1-m2) / S.

[0219] 6. Test method for pole piece compaction density

[0220] Remove the positive and negative electrodes from the lithium-ion battery and measure the electrode and current collector thicknesses. Take a certain area of ​​the electrode, measure its area, and weigh the mass of the film layer on the current collector after removing it. Calculate the electrode density based on this area and mass. The compacted density of the electrode, PD, is calculated as: electrode density / (electrode thickness - current collector thickness).

[0221] 7. Test method for electrolyte density

[0222] The density of the electrolyte can be measured by methods known to those skilled in the art, such as using a densitometer or a hydrometer. The following description uses a densitometer as an example.

[0223] At a temperature of 25°C-35°C, take the electrolyte to be measured and insert the rubber tube at the bottom of the densitometer into the electrolyte. Squeeze the rubber bulb of the densitometer to draw the electrolyte into the glass tube, causing the densitometer core to spring upward. The densitometer core should now float vertically within the glass tube and should not rest against it. The reading on the densitometer core at this point corresponds to the density of the electrolyte at a temperature of 25°C-35°C. Note that your line of sight should be level with the liquid surface when reading.

[0224] 8. Test method for electrolyte viscosity

[0225] The viscosity of the electrolyte can be measured by methods known to those skilled in the art, such as using a rotor viscometer or a ball viscometer. The following description uses the rotor viscometer as an example.

[0226] At room temperature (usually 25℃±5℃), place the electrolyte to be tested in the sample chamber and immerse the viscometer rotor in the electrolyte to be tested. After the test begins, the rotor settles in the electrolyte and the falling distance and time of the rotor are measured to obtain its falling acceleration. The viscosity of the electrolyte can be calculated according to the Stokes formula: a=(g(m-ρ) / μ×r 2 ).

[0227] Where a is the acceleration of the rotor falling, g is the acceleration due to gravity, m is the mass of the rotor, ρ is the density of the electrolyte, r is the radius of the rotor, and μ is the viscosity of the electrolyte.

[0228] The above calculation process is usually completed automatically by the computer system of the viscometer. Before starting the test, it is usually necessary to input the density of the electrolyte on the operation interface.

[0229] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A lithium-ion battery, characterized in that: The lithium-ion battery comprises: An electrolyte, wherein the electrolyte includes a lithium salt, and a concentration c of the lithium salt in the electrolyte satisfies: c ≥ 1 mol / L; The density ρ of the electrolyte satisfies: 0.9 g / mL≤ρ≤1.23 g / mL; The charging time t of the lithium-ion battery from 10% SOC to 80% SOC satisfies: 8.8 min≤t≤15 min.

2. The lithium-ion battery according to claim 1, wherein c≤1.8mol / L.

3. The lithium-ion battery according to claim 2, wherein 1.1mol / L≤c≤1.6mol / L.

4. The lithium-ion battery according to any one of claims 1 to 3, characterized in that 8.8min≤t≤10min.

5. The lithium-ion battery according to any one of claims 1 to 4, characterized in that The electrolyte includes a first solvent, and the first solvent includes at least one of ethylene carbonate, propylene carbonate, and ethyl methyl carbonate.

6. The lithium-ion battery according to any one of claims 1 to 5, characterized in that The electrolyte includes a second solvent, and the second solvent includes R1-COO-R2, wherein R1 and R2 each independently include one of an alkyl group with 1 to 5 carbon atoms and a halogenated alkyl group with 1 to 5 carbon atoms.

7. The lithium-ion battery according to claim 5 or 6, characterized in that The mass content X of the first solvent in the electrolyte satisfies: 20%≤X≤30%.

8. The lithium-ion battery according to claim 6, wherein The mass content Y of the second solvent in the electrolyte satisfies: 20%≤Y≤60%.

9. The lithium-ion battery according to any one of claims 1 to 8, characterized in that The lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate and lithium tetrafluorooxalatophosphate.

10. The lithium-ion battery according to claim 9, characterized in that The lithium salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, and the concentration of the lithium bis(fluorosulfonyl)imide in the lithium salt of the electrolyte is less than or equal to 30%.

11. The lithium-ion battery according to any one of claims 1 to 10, characterized in that The conductivity σ of the electrolyte satisfies: 13 mS / cm≤σ≤20 mS / cm.

12. The lithium-ion battery according to any one of claims 1 to 11, characterized in that The viscosity μ of the electrolyte satisfies: 2.2 cP≤μ≤2.7 cP.

13. The lithium-ion battery according to any one of claims 1 to 12, characterized in that The volume energy density VED of the lithium-ion battery satisfies: VED≥400Wh / L.

14. The lithium-ion battery according to any one of claims 1 to 13, characterized in that The lithium-ion battery includes a negative electrode plate, and the negative electrode plate includes a negative electrode film layer; The negative electrode film layer has a single-sided coating weight CW on the negative electrode sheet that satisfies: 0.06 mg / mm 2 ≤CW≤0.13mg / mm 2 .

15. The lithium-ion battery according to claim 14, characterized in that 0.08mg / mm 2 ≤CW≤0.115mg / mm 2 。 16. The lithium-ion battery according to claim 14 or 15, characterized in that: 0.09mg / mm 2 ≤CW≤0.105mg / mm 2 。 17. The lithium-ion battery according to any one of claims 14 to 16, characterized in that: The compaction density PD of the negative electrode film layer satisfies: 1.4 g / cc≤PD≤1.75 g / cc.

18. The lithium-ion battery according to claim 17, wherein: 1.55g / cc≤PD≤1.7g / cc.

19. The lithium ion battery according to claim 17 or 18, characterized in that 1.4g / cc≤PD≤1.6g / cc.

20. The lithium-ion battery according to any one of claims 1 to 19, characterized in that The lithium-ion battery includes a positive electrode plate, and the positive electrode plate includes a positive electrode film layer; The single-side coating weight CW' of the positive electrode film layer on the positive electrode sheet satisfies: 0.13 mg / mm 2 ≤CW'≤0.29mg / mm 2 .

21. The lithium-ion battery according to claim 20, characterized in that 0.19mg / mm 2 ≤CW’≤0.26mg / mm 2 。 22. The lithium ion battery according to claim 20 or 21, characterized in that 0.20mg / mm 2 ≤CW’≤0.24mg / mm 2 。 23. The lithium-ion battery according to any one of claims 20 to 22, characterized in that: The compaction density PD' of the positive electrode film layer satisfies: 2.5 g / cc≤PD'≤2.9 g / cc.

24. The lithium-ion battery according to claim 23, wherein: 2.6g / cc≤PD'≤2.8g / cc.

25. The lithium ion battery according to claim 23 or 24, characterized in that 2.7g / cc≤PD'≤2.8g / cc.

26. The lithium-ion battery according to any one of claims 1 to 25, characterized in that The filling coefficient a of the lithium-ion battery satisfies: 2.4 g / Ah≤a≤3.2 g / Ah.

27. The lithium ion battery according to any one of claims 1 to 26, characterized in that In the direction of gravity, the height h of the positive electrode film layer and / or the negative electrode film layer satisfies: 70 mm ≤ h ≤ 110 mm.

28. An electrical device, characterized in that: The electrical device comprises a lithium-ion battery according to any one of claims 1 to 27.

Images