Lithium-ion battery and electric apparatus

Abstract

The embodiments of the present application provide a lithium-ion battery and an electric apparatus, wherein a time (t) required to charge the lithium-ion battery from a 10% SoC to an 80% SoC satisfies: t ≤ 20 min, and the lithium-ion battery comprises a plurality of battery cells; each battery cell comprises a positive electrode active material, and the positive electrode active material comprises a lithium-containing transition metal oxide; the plurality of battery cells comprise a first battery cell and a second battery cell, wherein, during a charging process of the lithium-ion battery, a difference value (△T) at the same time between a temperature (T1) at a geometric center of a largest-area surface of the first battery cell and a temperature (T2) at a geometric center of a largest-area surface of the second battery cell satisfies: 0° C ≤ △T ≤ 8° C. Battery cells in the fast-charging lithium-ion battery exhibit good temperature consistency, and the lithium-ion battery has good cycling performance.

Description

Lithium-ion batteries and electrical devices

[0001] Cross-reference to related applications

[0002] This patent document claims priority and benefit to Chinese Patent Application No. 202510120662.0, filed on January 24, 2025, entitled "Lithium-ion Battery and Electrical Device". The entire contents of the aforementioned patent application are incorporated herein by reference as a part of the disclosure of this patent document. Technical Field

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

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

[0005] With people's increasing pursuit of efficiency, fast-charging lithium-ion batteries have become a key area of ​​development. However, lithium-ion batteries with positive electrode active materials including lithium-containing transition metal oxides suffer from rapid cycle life degradation. Therefore, improving the cycle performance of fast-charging lithium-ion batteries is a pressing technical problem that needs to be solved. Summary of the Invention

[0006] This application is made in view of the above-mentioned technical problems, and its purpose is to provide a lithium-ion battery and an electrical device, wherein the fast-charging lithium-ion battery has good cycle performance.

[0007] In a first aspect, a lithium-ion battery is provided, wherein the time t for charging the lithium-ion battery from 10% SOC to 80% SOC satisfies: t ≤ 20 min, the lithium-ion battery includes multiple battery cells; each battery cell includes a positive electrode active material, the positive electrode active material including a lithium-containing transition metal oxide; the multiple battery cells include a first battery cell and a second battery cell, and during the charging process of the lithium-ion battery, the temperature T1 at the geometric center of the surface with the largest area of ​​the first battery cell and the temperature T2 at the geometric center of the surface with the largest area of ​​the second battery cell at the same moment, ΔT, satisfies: 0℃ ≤ ΔT ≤ 8℃.

[0008] In the embodiments of this application, the lithium-ion battery is a lithium-ion battery with fast charging capability and the positive electrode active material includes lithium-containing transition metal oxide. By controlling the temperature difference between the first battery cell and the second battery cell at the same moment during the fast charging process to be within the range of 0°C to 8°C, the cycle performance of the entire fast-charging lithium-ion battery can be improved.

[0009] In one embodiment, the battery cell includes an electrolyte, and the ionic conductivity σ of the electrolyte satisfies: 9mS / cm≤σ≤25mS / cm.

[0010] In the embodiments of this application, by selecting an electrolyte with high ionic conductivity, the fast-charging performance of the battery cell is improved. At the same time, the electrolyte with high ionic conductivity also helps to reduce the polarization inside the battery cell, which helps to improve the cycle performance of the fast-charging battery cell, thereby improving the cycle performance of the lithium-ion battery.

[0011] In one embodiment, the lithium-ion battery includes a thermal management component attached to at least one surface of the battery cell, the thermal management component including a flow channel for containing fluid to regulate the temperature of the battery cell.

[0012] In one embodiment, the cross-sectional area of ​​the flow channel through the first battery cell is greater than the cross-sectional area of ​​the flow channel through the second battery cell.

[0013] In one embodiment, the contact area between the first battery cell and the flow channel is greater than the contact area between the second battery cell and the flow channel.

[0014] In one embodiment, the number of flow channels flowing through the first battery cell is greater than the number of flow channels flowing through the second battery cell.

[0015] In the embodiments of this application, the temperature at the first battery cell can be reduced by controlling the cross-sectional area of ​​the flow channel, the contact area between the battery cell and the flow channel, and the number of flow channels flowing through the battery cell, so that the temperature difference between the first battery cell and the second battery cell is within the designed range, thereby helping to improve the cycle performance of fast-charging lithium-ion batteries.

[0016] In one embodiment, the lithium-ion battery includes a heating element attached to at least one surface of the second battery cell.

[0017] In one embodiment, the lithium-ion battery includes a heat-insulating component, which is attached to at least one surface of the second battery cell.

[0018] In the embodiments of this application, the temperature of the second battery cell can be increased by setting a heating component and a heat preservation component at the second battery cell, so that the temperature difference between the first battery cell and the second battery cell is within the designed range, thereby helping to improve the cycle performance of the fast-charging lithium-ion battery.

[0019] In one embodiment, the capacity C of the battery cell satisfies: 60Ah ≤ C ≤ 200Ah.

[0020] The larger the capacity of a single battery cell, the more heat it generates during fast charging. By controlling the capacity of each battery cell within a suitable range, it is possible to reduce the heat generated during fast charging, thereby reducing the temperature difference between different battery cells in a lithium-ion battery and improving the cycle performance of fast-charging lithium-ion batteries.

[0021] In one embodiment, the electrolyte comprises a carboxylic acid ester solvent, which includes at least one of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl acrylate, and ethyl acrylate.

[0022] In the embodiments of this application, selecting carboxylic acid ester solvents helps to improve the ionic conductivity of the electrolyte, thereby improving the fast charging performance of the battery cell.

[0023] In one embodiment, based on the total mass of the electrolyte, the mass fraction W1 of the carboxylic acid ester solvent satisfies: 5wt% ≤ W1 ≤ 80wt%.

[0024] In one embodiment, the carboxylic acid ester solvent includes methyl acetate; based on the total mass of the electrolyte, the mass content W2 of the carboxylic acid ester solvent satisfies: 10%wt ≤ W2 ≤ 40wt.

[0025] In one embodiment, the lithium transition metal oxide includes Li x Ni (1-y-z) Co y M z O 2-b Wherein, M includes at least one element selected from Mn, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, Nb and Zr, 0 < x ≤ 1.2, 0.18 ≤ y ≤ 0.25, 0 ≤ z ≤ 0.2, 1 - yz ≥ 0.55, and 0 ≤ b ≤ 0.2.

[0026] In one embodiment, the electrolyte comprises a carbonate solvent, which includes at least one of ethylene carbonate, propylene carbonate, and ethyl methyl carbonate.

[0027] In one embodiment, the electrolyte comprises an electrolyte salt, wherein the electrolyte salt comprises LiFSI.

[0028] In a second aspect, an electrical device is provided, the electrical device comprising the lithium-ion battery in any embodiment of the first aspect. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0030] Figure 1 is a schematic structural diagram of a lithium-ion battery.

[0031] Figure 2 is another schematic structural diagram of a lithium-ion battery.

[0032] Figure 3 is a schematic structural diagram of a single battery cell.

[0033] Figure 4 is a schematic exploded view of a single battery cell.

[0034] Figure 5 is a cross-sectional view of a thermal management component.

[0035] Figure 6 is a top view of a flow channel. Detailed Implementation

[0036] The following detailed description of embodiments of the lithium-ion battery and power-consuming device of this application is provided with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0037] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0038] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] 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).

[0040] Unless otherwise specified, all steps in this 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 it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0041] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0042] Unless otherwise specified, any undefined terms shall have their technically accepted meanings.

[0043] The embodiments of this application will be described next.

[0044] In recent years, rechargeable batteries have seen significant development due to their high energy density and long lifespan, finding widespread application in power tools, electronic products, electric vehicles, aerospace, and other fields. Typically, a rechargeable battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of these active ions between the electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through, ensuring the normal electrochemical reaction of the rechargeable battery.

[0045] Taking lithium-ion batteries as an example, lithium-ion batteries are a typical type of rechargeable battery. Because they rely on the chemical reaction of lithium ions intercalating and deintercalating between the positive and negative electrodes for charging and discharging, lithium-ion batteries are also known as rocking chair batteries. During the charging process of a lithium-ion battery, lithium ions are extracted from the positive electrode active material, move to the negative electrode through the conduction of the electrolyte, and intercalate into the negative electrode active material; while during the discharging process, lithium ions are extracted from the negative electrode active material, move to the positive electrode through the conduction of the electrolyte, and intercalate into the positive electrode active material.

[0046] It should be understood that the “lithium intercalation” or “intercalation” process described in this application refers to the process in which lithium ions are intercalated into the positive electrode active material or the negative electrode active material due to an electrochemical reaction, while the “de-lithium extraction”, “de-lithium extraction”, or “de-intercalation” process described in this application refers to the process in which lithium ions are extracted from the positive electrode active material or the negative electrode active material due to an electrochemical reaction.

[0047] With the increasingly widespread application and diverse usage scenarios of lithium-ion batteries, new demands are being placed on their charging capabilities. For example, for electric vehicles, range anxiety and long charging times have become major obstacles to their development. Therefore, fast charging (FC) capability has become an important goal for the development of lithium-ion batteries. Fast charging, also known as FM, refers to charging a battery to full or near-full charge in a short period of time using high-power direct current. Different regions have different industry standards for the specific definition of fast charging. Generally, charging a battery to 80% of its full capacity in 30-60 minutes is considered fast charging; further, charging in less than 20 minutes is considered super-fast charging; and even further, charging in less than 15 minutes is considered extreme fast charging (XFC). However, research has shown that high-rate charging causes rapid degradation of battery capacity, output power, and other performance characteristics. Therefore, in addition to meeting the requirements of fast charging, fast-charging batteries also need to achieve a certain cycle life and meet relevant safety and electrochemical performance standards. In the embodiments of this application, fast-charging lithium-ion battery refers to a lithium-ion battery with fast-charging capability.

[0048] Figure 1 is a schematic structural diagram of a lithium-ion battery. As shown in Figure 1, the lithium-ion battery 10 can be a single physical module comprising multiple battery cells 20 connected in series, parallel, or mixed connections to provide higher voltage and capacity. The lithium-ion battery 10 may also include a housing 3 in which the battery cells 20 are housed.

[0049] The housing 3 has a hollow interior structure, and multiple battery cells 20 are placed inside the housing 3 after being connected in parallel, series, or mixed. The housing 3 may include a first housing section 31 and a second housing section 32, which are closed together to form the housing 3. The shapes of the first housing section 31 and the second housing section 32 can be determined according to the shape of the components contained inside, for example, according to the shape of the combination of multiple battery cells 20 contained inside. At least one of the first housing section 31 and the second housing section 32 has an opening. As shown in Figure 1, the first housing section 31 and the second housing section 32 can both be hollow cuboids with one face as an opening. The openings of the first housing section 31 and the second housing section 32 are arranged opposite to each other, and the first housing section 31 and the second housing section 32 are interlocked to form a housing 3 with a closed chamber, which can be used to accommodate multiple battery cells 20. Multiple battery cells 20 are connected in parallel, series, or mixed and placed inside the housing 3 formed by the first housing part 31 and the second housing part 32.

[0050] For example, unlike that shown in Figure 1, only one of the first housing portion 31 and the second housing portion 32 may be a hollow cuboid with an opening, while the other is plate-shaped to cover the opening. Taking the second housing portion 32 as a hollow cuboid with one opening, and the first housing portion 31 as a plate-shaped example, then the first housing portion 31 covers the opening of the second housing portion 32 to form a housing 3 with a closed chamber, which can be used to accommodate multiple battery cells 20.

[0051] For example, the box 3 may also include a first box part 31, a second box part 32 and a third box part 33 as shown in Figure 2, and the first box part 31, the second box part 32 and the third box part 33 are fitted together to form the box 3.

[0052] It should be understood that Figure 1 only shows the case where the lithium-ion battery 10 includes 8 battery cells 20 arranged in a 2×4 pattern. However, the number of battery cells 20 in the lithium-ion battery 10 is not limited to this. For example, the lithium-ion battery may also include X×Y×Z battery cells 20, where X, Y, and Z are all positive integers. For example, 24 battery cells 20 arranged in a 2×4×3 pattern along the length, width, and height.

[0053] The applicant's research revealed that during fast charging, the temperature difference between different battery cells 20 in the lithium-ion battery 10 affects the cycle performance of the lithium-ion battery 10. A possible reason is that higher temperatures result in less resistance to electron movement within the battery cell 20, thus the DC resistance (DCR) of the battery cell 20 with a relatively higher temperature in the lithium-ion battery 10 is relatively lower. For the lithium-ion battery 10, the charging current of each battery cell 20 is presumably evenly distributed during charging. If a battery cell 20 has a relatively higher temperature and a relatively lower DCR, then that battery cell 20 will actually bear a current greater than the evenly distributed current value. For example, for two parallel battery cells 20 capable of 4C charging, if the system provides an 8C charging current, then each battery should theoretically be charged with a 4C charging current. Assuming that the temperature of one battery cell 20 is higher than that of another, the DCR of the higher-temperature battery cell 20 will be lower than that of the lower-temperature battery cell 20. Therefore, the higher-temperature battery cell 20 will bear a charging current greater than 4C, exceeding its charging current limit and thus worsening its cycle life. Furthermore, as cycling continues, the rate of side reactions within the higher-temperature battery cell 20 will be higher than that of the lower-temperature battery cell 20, causing its DCR to continuously increase. When it exceeds the DCR of the lower-temperature battery cell 20, it will again bear a charging current greater than 4C in the later stages of the cycle, further worsening its cycle life. Due to the series, parallel, and mixed connection relationships of the battery cells 20, the cycle performance of the lithium-ion battery 10 will be limited by the battery cell 20 with the worst cycle performance. Therefore, the temperature difference between different battery cells 20 during fast charging affects the cycle life of the lithium-ion battery 10.

[0054] Meanwhile, the applicant also found that temperature difference has a greater impact on the cycle performance of lithium-ion batteries 10 whose positive electrode active material includes lithium transition metal oxides. The possible reason is that battery cells 20 with positive electrode active materials including lithium transition metal oxides inherently exhibit a certain degree of DCR growth during cycling and storage, and temperature has a significant impact on the DCR growth of these battery cells 20. For example, the higher the temperature, the faster the DCR growth rate of the battery cell 20. Therefore, given that the positive electrode active material includes lithium transition metal oxides in the battery cells 20, temperature difference will also affect the DCR growth rate of different battery cells 20, further deteriorating the DCR consistency of different battery cells 20 in the lithium-ion battery 10, and affecting the cycle performance of the lithium-ion battery 10. Therefore, for lithium-ion batteries 10 with positive electrode active materials including lithium transition metal oxides, the temperature difference between different battery cells 20 has a more prominent impact on their cycle performance.

[0055] Based on this, this application provides a lithium-ion battery 10 and an electrical device. During fast charging, the temperature difference between different battery cells 20 is controlled within a small range, which can effectively improve the impact of the temperature difference between different battery cells 20 on the cycle life of the lithium-ion battery 10, thereby improving the cycle performance of the fast-charging lithium-ion battery 10.

[0056] Next, we will give a detailed introduction to the lithium-ion battery 10 provided in this application.

[0057] [Lithium-ion battery]

[0058] First, a lithium-ion battery 10 is provided. Figure 2 is another schematic structural diagram of a lithium-ion battery 10 according to this application.

[0059] As shown in Figure 2, the lithium-ion battery 10 includes multiple battery cells 20. The time t for charging the lithium-ion battery 10 from 10% SOC to 80% SOC satisfies: t ≤ 20 min. Each battery cell includes a positive electrode active material, which includes a lithium-containing transition metal oxide. The multiple battery cells include a first battery cell and a second battery cell. During the charging process of the lithium-ion battery 10, the temperature difference ΔT between the geometric center of the largest surface area of ​​the first battery cell 21 and the geometric center of the largest surface area of ​​the second battery cell 22 at the same time satisfies: 0℃ ≤ ΔT ≤ 8℃.

[0060] In other words, the first battery cell 21 is the battery cell 20 with a relatively higher temperature at that moment, and the second battery cell 22 is the battery cell 20 with a relatively lower temperature at that moment, i.e., T1 > T2.

[0061] For example, referring to Figure 1-2, a battery cell 20 located in the middle of the lithium-ion battery 10, surrounded by other battery cells 20, may experience lower heat dissipation as charging progresses compared to battery cells 20 located at the edges, resulting in a higher temperature for the latter. Conversely, battery cells 20 at the edges may have better heat dissipation, and the fluid in the thermal management component typically flows through these edge cells first before passing through the other cells. The fluid's initial temperature upon entering the thermal management component is lower, and combined with the better heat dissipation of the edge cells, their temperature is lower than that of the cells at other locations. Furthermore, the ambient temperature affects the assembly of the battery cells 20 into the lithium-ion battery 10. Therefore, in reality, multiple factors can cause temperature differences between battery cells 20 located at different positions within the lithium-ion battery 10.

[0062] Specifically, △T can be 0℃, 1℃, 2℃, 3℃, 4℃, 5℃, 6℃, 7℃, 8℃, or a value within the range obtained by any combination of the above two values. Unless otherwise specified, T1 in this application is greater than or equal to T2.

[0063] The temperature of the individual cells 20 in the lithium-ion battery 10 during charging can be monitored through a battery management system (BMS). This allows for the acquisition of the temperature curve of the geometric center of the surface with the largest area of ​​each cell 20 during charging, thus obtaining the temperature of each cell 20 at a specific moment during charging. The difference between the temperatures of the first cell 21 and the second cell 22 at that moment yields the value of ΔT. More specifically, the BMS may include a temperature measuring device to monitor the temperature of the individual cells 20. In the absence of a BMS, the temperature of the individual cells 20 during charging can be monitored by installing temperature measuring devices on them within the lithium-ion battery 10, obtaining the temperature curve of each cell 20 during charging, and thus obtaining the value of ΔT. The temperature measuring device can be, for example, an infrared thermometer or a resistance thermometer.

[0064] The charging time mentioned above refers to the charging time measured when charging the lithium-ion battery 10 at a certain charging power. The charging power can be, for example, 120W, 150W, 180W, 200W, 300W, 400W, etc.

[0065] The battery cell includes an electrode assembly, which includes a positive electrode sheet. The positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes a positive electrode active material. Lithium transition metal oxides refer to a class of oxides including lithium and transition metal elements. Structurally, they include ternary materials with layered structures, LiCoO2, LiNiO2, etc., and also include LiMn2O4 with a spinel structure, etc. Ternary materials refer to lithium transition metal oxides including three different transition metal elements. It should be understood that ternary materials may also be doped with trace amounts of other transition metal elements, and ternary materials doped with other transition metal elements are generally considered to still be ternary materials. In this embodiment, lithium transition metal oxides typically have a high specific capacity. Selecting lithium transition metal oxides as at least part of the positive electrode active material helps to improve the energy density of the battery cell 20 and the lithium-ion battery 10.

[0066] Therefore, in the lithium-ion battery 10, which is composed of a battery cell 20 containing a lithium transition metal oxide as the positive electrode active material, by controlling the temperature difference between the first battery cell 21 and the second battery cell 22 at the same time to be within the range of 0°C to 8°C, in other words, by controlling the temperature difference between each battery cell 20 in the lithium-ion battery 10 to not exceed 8°C during the entire fast charging process, the consistency of different battery cells 20 during fast charging can be effectively improved, thereby improving the fast charging cycle performance of the entire lithium-ion battery 10.

[0067] Figure 3 is a schematic structural diagram of a battery cell 20 according to this application. Figure 4 is a schematic exploded view of a battery cell 20. As shown in Figures 3 and 4, the battery cell 20 typically includes a housing 201 and an electrode assembly 202 disposed within the housing 201. The housing 201 is a component used to encapsulate the electrode assembly 202 and the electrolyte. The material of the housing 201 can be steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc. The housing 201 may include multiple walls, making the battery cell 20 a polyhedral structure. Specifically, the housing 201 includes a shell 2012 and an end cap 2011. Exemplarily, the housing 201 can be a cuboid or approximately cuboid, and the housing 201 may include six walls, each wall being rectangular or approximately rectangular. Correspondingly, the shell 2012 can also be a polyhedral structure with openings.

[0068] The housing 2012 can have various shapes, such as a cylinder or a cuboid. The shape of the housing 2012 can be determined according to the specific shape of the electrode assembly 202. For example, if the electrode assembly 202 is a cylindrical structure, then the housing 2012 can be a cylindrical structure; if the electrode assembly 202 is a cuboid structure, then the housing 2012 can be a cuboid structure. Of course, the end cap 2011 can also have various structures, such as a plate-like structure or a hollow structure with one end open. It should be understood that the housing 201 is not limited to the aforementioned structures. The housing 201 can also have other structures. For example, the housing 201 includes a housing 2012 and two end caps 2011. The housing 2012 is a hollow structure with openings on both sides. One end cap 2011 is fitted onto one opening of the housing 2012 to form a sealed connection, thereby forming a sealed space for accommodating the electrode assembly 202 and the electrolyte.

[0069] Therefore, the battery cell 20 has a certain shape and volume, and the temperature at different locations of the battery cell 20 may vary during charging. Unless otherwise specified, the temperature of the battery cell 20 during charging as mentioned in this application refers to the temperature at the geometric center of the surface with the largest area of ​​the battery cell 20, as shown at point A in Figure 3-4.

[0070] The lithium-ion battery 10 has a fast-charging capability that allows it to be charged from 10% SOC to 80% SOC in less than or equal to 20 minutes. In this case, each individual cell 20 in the lithium-ion battery 10 also has a fast-charging capability that allows it to be charged from 10% SOC to 80% SOC in less than or equal to 20 minutes. Furthermore, based on the series, parallel, and mixed-connection relationships of the individual cells 20 in the lithium-ion battery 10, if one cell 20 in the lithium-ion battery 10 loses its aforementioned fast-charging capability due to rapid capacity decay, the lithium-ion battery 10 will be limited by that single cell 20 and will also lose its aforementioned fast-charging capability.

[0071] The fast charging process can be either a constant current charging process or a stepped charging process. A constant current charging process involves charging the battery cell 20 at a fixed charging rate. The charging rate represents the ratio of the charging current to the capacity of the battery cell 20. For example, for a battery supporting 4C charging, the charging current can reach four times the battery capacity. The charging rate can be calculated using the ratio of the charging current to the capacity of the battery cell 20. During the fast charging process of the battery cell 20, the charging rate can also vary. For example, with a charging rate greater than or equal to 2.8C, the charging time from 10% SOC to 80% SOC for the battery cell 20 is less than or equal to 15 minutes. In other words, during the process of charging from 10% SOC to 80% SOC, the charging rate may gradually decrease from greater than 2.8C to less than 2.8C. During this process, the battery cell 20 may undergo a transition from constant current charging to constant voltage charging; therefore, the charging rate does not have to be constant. For example: Battery cell 20 is charged at room temperature (25°C) from 10% SOC to 80% SOC in 10 minutes (equivalent charge rate ≥ 4C). The charging process can be as follows: initially charged 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, ending the charging process. The charging time for battery cell 20 from 0% SOC to 100% SOC at 1C is 60 minutes. Therefore, given that the charging time for the battery cell 20 from 10% SOC to 80% SOC is measured to be 10 minutes, the equivalent charging rate of this process can be calculated as: [(80% SOC - 10% SOC) / (100% SOC - 0% SOC)] × [(1C × 60min) / 10min] = 4.2C.

[0072] If the battery cell 20 is charged on a charging station with a power of 120W or higher, the time it takes to charge from 10% SOC to 80% SOC can be directly recorded. For example, if the time is around 15 minutes (with an error of no more than 1 minute), it is generally considered a 4C fast-charging battery. Another example: if the time is around 12 minutes (with an error of no more than 1 minute), it is generally considered a 5C fast-charging battery. Yet another example: if the time is around 10 minutes (with an error of no more than 1 minute), it is generally considered a 6C fast-charging battery.

[0073] Additionally, as shown in Figures 3-4, the battery cell 20 includes an electrode assembly 202, which is typically formed by winding or stacking a positive electrode, a separator, and a negative electrode. Structurally, the electrode assembly 202 includes tabs 2021 and a body portion 2022. The tabs 2021 are formed by stacking and connecting the areas of the positive or negative electrode that are not coated with positive active material. The body portion 2022 is formed by stacking or winding the areas of the positive or negative electrode that are coated with active material. The tabs are connected to the electrode terminals 21 on the end cap 2011 to input or output current to the electrode assembly 202.

[0074] Electrode terminals 21 are components used to output or input electrical energy to the battery cell 20. The electrode terminals can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy. A battery cell 20 typically includes two electrode terminals 21 with opposite polarities. The two electrode terminals 21 can be located on the same wall of the battery cell 20 or on different walls. In the example shown in Figures 3-4, the electrode terminals 21 can both be located on the end cap. In another example, the electrode terminals 21 can be located on two opposite walls of the battery cell 20, such as the top and bottom walls. The arrangement of the electrode terminals 21 can be flexibly adjusted according to the position of the tabs 2021.

[0075] Next, we will provide a more detailed introduction on how to control and regulate the temperature difference to improve the fast charging cycle performance of the lithium-ion battery 10.

[0076] In one embodiment, the battery cell 20 includes an electrolyte, the ionic conductivity σ of which satisfies: 9mS / cm≤σ≤25mS / cm.

[0077] Specifically, σ can be 9 mS / cm, 10 mS / cm, 11 mS / cm, 12 mS / cm, 13 mS / cm, 14 mS / cm, 15 mS / cm, 16 mS / cm, 17 mS / cm, 18 mS / cm, 19 mS / cm, 20 mS / cm, 21 mS / cm, 22 mS / cm, 23 mS / cm, 24 mS / cm, 25 mS / cm, or a value within the range obtained by any combination of the above two values.

[0078] It should be understood that, unless otherwise specified, the ionic conductivity mentioned in this application refers to the ionic conductivity of the electrolyte at 20℃ to 30℃. The higher the ionic conductivity of the electrolyte, the more conducive it is to the rapid movement of lithium ions inside the battery cell 20, which can improve the fast charging performance of the battery cell 20.

[0079] In this embodiment, by selecting an electrolyte with an ionic conductivity in the range of 9 mS / cm to 25 mS / cm, it is helpful to improve the fast charging performance of the battery cell 20, enabling the battery cell 20 to have the fast charging capability of charging from 10% SOC to 80% SOC within 20 minutes.

[0080] Figure 5 is a cross-sectional view of a thermal management component.

[0081] Referring to Figures 2 and 5, in one embodiment, the lithium-ion battery 10 includes a thermal management component 40, which is attached to at least one surface of the battery cell 20. The thermal management component 40 includes a flow channel 41 for containing fluid to regulate the temperature of the battery cell 20.

[0082] Specifically, the thermal management component 40 may include a first heat-conducting plate 401 and a second heat-conducting plate 402. The flow channel 41 can be formed by providing grooves on the first heat-conducting plate 401 and / or the second heat-conducting plate 402. Taking the provision of a groove on the second heat-conducting plate 402 as an example, the second heat-conducting plate 402 is provided with a groove with an opening facing the first heat-conducting plate 401. When the first heat-conducting plate 401 and the second heat-conducting plate 402 are attached together, the first heat-conducting plate 401 covers the opening of the groove, thereby forming a hollow structure as shown in FIG. 5. This hollow structure is the flow channel 41.

[0083] It should be understood that, although not shown in Figures 2 and 5, the flow channel 41 has an inlet and an outlet. Fluid flows into the thermal management component 40 from the inlet and exits from the outlet after passing through the flow channel 41. The inlet and outlet can be part of the flow channel 41 or independent components connected to the flow channel 41. Flow channels 41 can be independent of each other or interconnected. The flow channels 41 shown in Figures 2 and 5 are strip-shaped, but the embodiments of this application are not limited to this.

[0084] Referring again to Figures 2 and 4, the thermal management component 40 can be attached to at least one surface of the battery cell 20. This can be achieved by attaching the first heat-conducting plate 401 of the thermal management component 40 to the bottom wall surface of the battery cell 20, or the first heat-conducting plate 401 of the thermal management component 40 to the side wall surface of the battery cell 20. Considering that the first heat-conducting plate 401 is a flat surface, it is preferable to attach the first heat-conducting plate 401 to at least one surface of the battery cell 20. When there are a large number of battery cells 20 in the lithium-ion battery 10, the thermal management component 40 can also be attached to both the bottom wall and the side wall of the battery cell simultaneously. "Attachment" can mean that the thermal management component 40 is directly attached to the surface of the battery cell 20, or it can be attached using an adhesive such as thermally conductive adhesive, to achieve heat exchange between the thermal management component 40 and the battery cell 20.

[0085] Therefore, after the fluid in the flow channel 41 flows into the thermal management component 40, it exchanges heat with the battery cell 20 while flowing in the flow channel 41, and then flows out of the thermal management component 40 to regulate the temperature of the battery cell 20, for example, to raise or lower the temperature of the battery cell 20. Unless otherwise specified, the thermal management component 40 in this application is used to lower the temperature of the battery cell 20. The fluid in the flow channel can be water, or a fluid with good thermal conductivity and chemical stability, such as ethylene glycol or propylene glycol.

[0086] As mentioned earlier, at least one wall of the battery cell 20 will be provided with an electrode terminal 21. The series and parallel connection of multiple battery cells 20 in the lithium-ion battery 10 needs to be achieved by connecting the electrode terminals 21 of different battery cells 20 through a busbar component. Therefore, the wall where the electrode terminal 21 is located is not suitable for setting up a thermal management component.

[0087] Based on this, in one example, as shown in Figures 3-4, both electrode terminals 21 are disposed on the end cap 2011. In this case, the thermal management component 40 can be attached to the bottom wall and / or at least one side wall of the battery cell 20. In the scheme of attaching the battery cell 20 to the side wall, it is preferable to attach the thermal management component 40 to the side wall with the largest area to obtain a better cooling effect. Unlike Figures 3-4, in another example, the electrode terminals 21 are respectively disposed on two opposite side walls. In this case, the thermal management component 40 can be attached to the bottom wall and / or top wall of the battery cell 20, and / or at least one remaining side wall.

[0088] In one embodiment, the cross-sectional area of ​​the flow channel through the first battery cell 21 is greater than the cross-sectional area of ​​the flow channel through the second battery cell 22.

[0089] Specifically, the larger the cross-sectional area of ​​the flow channel, the more fluid flows through that location, resulting in more heat exchange with the battery cell 20 and a better cooling effect on the battery cell 20. The flow channel 41 in the thermal management component 40 can be designed so that the cross-sectional area of ​​the flow channel at the first battery cell 21 is larger than that at the second battery cell 22, thereby improving the cooling effect at the first battery cell 21, reducing its temperature, and decreasing the temperature difference between the first battery cell 21 and the second battery cell 22, controlling the temperature difference between them within the range of 0℃ to 8℃.

[0090] Figure 6 is a top view of a flow channel 41 according to an embodiment of this application.

[0091] During the fast charging process of the lithium-ion battery 10, the positions of the first battery cell 21 and the second battery cell 22 may differ at different times, while the position of the flow channel 41 remains fixed. Generally speaking, during the entire fast charging process, the battery cell 20 closer to the center of the lithium-ion battery 10 is surrounded by other battery cells 20 and has a higher temperature; the battery cell 20 closer to the casing 3 of the lithium-ion battery 10 has better heat dissipation and a lower temperature. Therefore, the flow channel 41 can be configured as a shape that is narrow at both ends and wide in the middle, as shown in Figure 6, so that the cross-sectional area of ​​the flow channel 41 at the first battery cell 21 is larger than the cross-sectional area of ​​the flow channel 41 at the second battery cell 22 during fast charging.

[0092] Therefore, by designing the cross-sectional area of ​​the flow channel through the first battery cell 21 to be larger than the cross-sectional area of ​​the flow channel through the second battery cell 22, this embodiment can reduce the temperature difference between the first battery cell 21 and the second battery cell 22, so that the temperature difference between the first battery cell 21 and the second battery cell 22 is controlled within the range of 0℃ to 8℃. This effectively improves the temperature consistency of the battery cells 20 during fast charging of the lithium-ion battery 10, and helps to improve the cycle performance of the entire fast-charging lithium-ion battery 10.

[0093] In one embodiment, the contact area between the first battery cell 21 and the thermal management component 40 is greater than the contact area between the second battery cell 22 and the thermal management component 40.

[0094] Specifically, the bottom wall surfaces of the first battery cell 21 and the second battery cell 22 can both be provided with the same thermal management component 40. In addition, a thermal management component 40 can be added to the side wall surface of the first battery cell 21 so that the contact area between the first battery cell 21 and the thermal management component 40 is greater than the contact area between the second battery cell 22 and the thermal management component 40.

[0095] The larger the contact area between the battery cell 20 and the thermal management component 40, the larger the area available for heat exchange, resulting in higher heat exchange efficiency and better cooling effect. Therefore, this embodiment, by controlling the contact area between the battery cell 20 and the thermal management component 40 to satisfy the above relationship, can reduce the temperature difference between the first battery cell 21 and the second battery cell 22, keeping the temperature difference between them within the range of 0℃ to 8℃. This effectively improves the temperature consistency of the battery cells 20 during fast charging of the lithium-ion battery 10, helping to improve the overall cycle performance of the fast-charging lithium-ion battery 10.

[0096] In one embodiment, the number of channels flowing through the first battery cell 21 is greater than the number of channels flowing through the second battery cell 22.

[0097] With the same cross-sectional area of ​​the flow channels, the contact area between the battery cell 20 and the thermal management component 40 can also be controlled by controlling the number of flow channels flowing through the first battery cell 21 and the second battery cell 22, thereby regulating the temperature difference between the first battery cell 21 and the second battery cell 22, so that the temperature difference between the first battery cell 21 and the second battery cell 22 is controlled within the range of 0℃ to 8℃, effectively improving the temperature consistency of the battery cell 20 during fast charging of the lithium-ion battery 10, and helping to improve the cycle performance of the entire fast-charging lithium-ion battery 10.

[0098] In one embodiment, the lithium-ion battery 10 includes a heating element attached to at least one surface of the second battery cell 22.

[0099] Specifically, the heating element can be a heating film, heating wire, etc. For example, the heating element can be attached to one or more sidewalls of the second battery cell 22 to heat the second battery cell 22 during the fast charging process of the lithium-ion battery 10. The heating element can continuously heat the second battery cell 22 during the fast charging process of the lithium-ion battery 10, or it can heat the second battery cell 22 according to its temperature. For example, a temperature sensing element can be set at the second battery cell 22 to obtain the temperature of the second battery cell 22 in real time during the fast charging process. When the temperature of the second battery cell 22 is sensed to be lower than a preset threshold, the heating element heats the second battery cell 22. Alternatively, when the rate of temperature drop of the second battery cell 22 is sensed to be higher than a preset threshold, the heating element heats the second battery cell 22. The number of heating elements can be flexibly adjusted according to the number and arrangement of the battery cells 20 in the lithium-ion battery 10.

[0100] In this embodiment, by attaching a heating element to at least one surface of the second battery cell 22, the temperature of the second battery cell 22 during fast charging can be increased, thereby reducing the temperature difference between the first battery cell 21 and the second battery cell 22. This allows the temperature difference between the first battery cell 21 and the second battery cell 22 to be controlled within the range of 0°C to 8°C, improving the temperature consistency of the battery cells 20 during fast charging and thus improving the overall cycle performance of the fast-charging lithium-ion battery 10.

[0101] In one embodiment, the lithium-ion battery 10 includes a heat-insulating component attached to at least one surface of the second battery cell 22.

[0102] Specifically, the insulation component can be insulation cotton, vacuum insulation board, foam board, fiberglass, etc. Applying an insulation component to at least one surface of the second battery cell 22 can reduce heat loss from the second battery cell 22, thereby increasing the temperature of the second battery cell 22 during fast charging. The number of insulation components can be flexibly adjusted according to the number and arrangement of the battery cells 20 in the lithium-ion battery 10.

[0103] In this embodiment, by attaching a heat-insulating component to at least one surface of the second battery cell 22, the temperature difference between the first battery cell 21 and the second battery cell 22 can be reduced, so that the temperature difference between the first battery cell 21 and the second battery cell 22 is controlled within the range of 0°C to 8°C, thereby improving the temperature consistency of the battery cells 20 during fast charging of the lithium-ion battery 10 and thus improving the cycle performance of the entire fast-charging lithium-ion battery 10.

[0104] In one embodiment, the capacity C of the battery cell 20 satisfies: 60Ah ≤ C ≤ 200Ah.

[0105] Specifically, C can be 60Ah, 70Ah, 80Ah, 90Ah, 100Ah, 110Ah, 120Ah, 130Ah, 140Ah, 150Ah, 160Ah, 170Ah, 180Ah, 190Ah, 200Ah, or a value within the range obtained by any combination of the above two values.

[0106] The larger the capacity of a single battery cell 20, the more heat is generated and the greater the temperature rise during charging. The greater the temperature rise of a single battery cell 20, the greater the temperature difference between different battery cells 20. This is because, due to the arrangement of the battery cells 20, the heat dissipation of battery cells 20 at different positions varies. Compared to a situation with a smaller temperature rise, a larger temperature rise in a single battery cell 20 means that battery cells 20 located in the middle accumulate more heat and reach higher temperatures, while battery cells located at the edges can dissipate heat more quickly, and their temperatures may be comparable to or only slightly higher than in a situation with a smaller temperature rise. Therefore, the greater the temperature rise of a single battery cell 20, the greater the temperature difference between different battery cells 20.

[0107] Therefore, by controlling the capacity of the battery cell 20 within a suitable range, the temperature rise of the battery cell 20 during fast charging can be controlled, thereby helping to reduce the temperature difference between the first battery cell 21 and the second battery cell 22, improving the temperature consistency of the battery cells 20 during fast charging, and thus improving the cycle performance of the entire fast-charging lithium-ion battery 10.

[0108] In one embodiment, the electrolyte comprises a carboxylic acid ester solvent, which includes at least one of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl acrylate, and ethyl acrylate.

[0109] Specifically, carboxylic acid ester solvents have lower density and viscosity, and higher ionic conductivity. In this embodiment, by selecting a carboxylic acid ester solvent as at least part of the electrolyte solvent, the ionic conductivity of the electrolyte can be improved. On the one hand, improving the ionic conductivity of the electrolyte helps to enhance the fast-charging performance of the battery cell 20. On the other hand, improving the ionic conductivity of the electrolyte helps to reduce the initial DCR of the battery cell 20, that is, the DCR of the battery cell 20 before fast-charging cycle. The smaller the initial DCR of the battery cell 20, the smaller the temperature rise of the battery cell 20 during fast charging, the smaller the temperature difference between different battery cells 20 in the lithium-ion battery 10 during fast charging, and the better the cycle performance of the lithium-ion battery.

[0110] Therefore, by adding carboxylic acid ester solvents to the electrolyte, the fast-charging cycle performance of the lithium-ion battery 10 can be improved.

[0111] In one embodiment, based on the total mass of the electrolyte, the mass content W1 of the carboxylic acid ester solvent satisfies: 5wt% ≤ W1 ≤ 80wt%; optionally, 10wt% ≤ W1 ≤ 40wt%.

[0112] Specifically, W1 can be 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, or a value within the range obtained by any combination of the above two values. Carboxylic acid ester solvents are beneficial for improving the ionic conductivity of the electrolyte, thereby reducing the initial DCR of the battery cell 20. However, carboxylic acid ester solvents have poor compatibility with the negative electrode active material, which may cause side reactions and gas production at the negative electrode. The side reaction products increase the DCR of the battery cell 20 and are detrimental to the safety performance of the battery cell 20. The temperature rise of the battery cell 20 during fast charging is actually higher, which is not conducive to the temperature difference control between different battery cells 20 in the lithium-ion battery 10.

[0113] Therefore, by controlling the mass content of carboxylic acid ester solvents within a suitable range, this embodiment can reduce the initial DCR of battery cell 20, reduce the temperature rise of battery cell 20 during fast charging, thereby reducing the temperature difference between different battery cells 20 in lithium-ion battery 10 and improving the cycle performance of lithium-ion battery 10. Simultaneously, it can improve the compatibility between the electrolyte and the negative electrode active material, reduce the risk of side reactions between the electrolyte and the negative electrode active material, and further help improve cycle performance. Thus, by controlling the mass content of carboxylic acid ester solvents in the electrolyte within the aforementioned range, the cycle performance of lithium-ion battery 10 can be improved.

[0114] In one embodiment, the lithium transition metal oxide includes Li x Ni (1-y-z) Co y M z O 2-b Wherein, M includes at least one element selected from Mn, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, Nb and Zr, 0 < x ≤ 1.2, 0.18 ≤ y ≤ 0.25, 0 ≤ z ≤ 0.2, 1 - yz ≥ 0.55, and 0 ≤ b ≤ 0.2.

[0115] In one embodiment, the electrolyte comprises a carbonate solvent, which includes at least one of ethylene carbonate, propylene carbonate, and ethyl methyl carbonate.

[0116] Specifically, carbonate solvents are more stable than carboxylic acid ester solvents and have better compatibility with the negative electrode active material, enabling the formation of a stable interfacial film. Introducing carbonate solvents into the electrolyte helps reduce side reactions between carboxylic acid ester solvents and the negative electrode active material, thereby helping to reduce the DCR growth of the battery cell 20 during cycling, reduce the temperature rise of the battery cell 20 during fast charging, and thus reduce the temperature difference between different battery cells 20, improving the consistency of the battery cells 20. Therefore, this embodiment, by combining a carbonate solvent with a carboxylic acid ester solvent as the electrolyte solvent, helps to improve the cycle performance of the lithium-ion battery 10.

[0117] In one embodiment, the electrolyte comprises an electrolyte salt, which includes LiFSI.

[0118] Specifically, LiFSI, or lithium bisfluorosulfonyl imide, has high solubility in carboxylic acid ester solvents, which helps to improve the ionic conductivity of the electrolyte, reduce the initial DCR of the battery cell 20, reduce the temperature rise of the battery cell 20 during fast charging, and reduce the temperature difference between different battery cells 20. Furthermore, LiFSI exhibits stability at high temperatures. Therefore, selecting LiFSI as the electrolyte salt helps to further improve the cycle performance of the lithium-ion battery 10.

[0119] Next, we will introduce the negative electrode, positive electrode, and separator in the battery cell 20 in more detail.

[0120] [Negative electrode plate]

[0121] A negative electrode typically includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector. The negative electrode film layer includes a negative electrode active material.

[0122] As an example, the negative electrode current collector has two surfaces opposite each other in its own 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.

[0123] 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 polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. 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 polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0124] In one embodiment, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. 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, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional 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.

[0125] In one embodiment, the negative electrode active material is a silicon-containing material. The silicon-containing material includes at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, silicon-containing alloys, or silicon-oxygen-carbon composites. By selecting a silicon-containing material as the negative electrode active material, it is beneficial to further improve the volumetric energy density of the battery cell 20. Combined with the structural design of the battery cell 20 in the aforementioned embodiments, the battery cell 20 can possess both high energy density and excellent safety performance.

[0126] In one embodiment, the negative electrode film layer further includes an adhesive. The adhesive may 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).

[0127] In one embodiment, the negative electrode film layer further includes a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0128] In one embodiment, the negative electrode film layer also includes other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0129] In one embodiment, the negative electrode sheet can be prepared by forming a negative electrode slurry using the components described above. 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 a negative electrode current collector, and after drying, cold pressing, and other processes, the negative electrode sheet is obtained.

[0130] [Positive electrode plate]

[0131] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0132] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0133] In one embodiment, the positive 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 substrate and a metal layer formed on at least one surface of the polymer substrate. 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 substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0134] In another embodiment, the positive electrode active material may also be a known positive electrode active material for batteries. As an example, the positive electrode active material may also include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Examples of lithium-containing phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. During the charging and discharging process, Li undergoes insertion / extraction and consumption, resulting in different molar contents of Li in the positive electrode active material when the battery is discharged to different states. In the examples of positive electrode active materials in this application, the molar content of Li refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar content of Li changes when the positive electrode active material is applied to the battery system. In the examples of positive electrode active materials in this application, the molar content of O is only an ideal value; lattice oxygen release causes changes in the molar content of O, and the actual molar content of O will fluctuate.

[0135] 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), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0136] In one embodiment, the positive electrode film layer further includes a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0137] In one embodiment, the positive electrode sheet can be prepared by forming a positive electrode slurry from the components described above. For example, a first positive electrode active material and / or a 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 onto a positive electrode current collector, and after drying, cold pressing, and other processes, the positive electrode sheet is obtained.

[0138] Electrolyte

[0139] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0140] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0141] In some embodiments, the electrolyte salt may be selected from 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 difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0142] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0143] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0144] [Isolation membrane]

[0145] This application does not impose any particular restrictions on the type of separator membrane. For example, any well-known porous separator membrane with good chemical and mechanical stability can be selected.

[0146] In one embodiment, the material of the separator can be selected from at least one of glass fiber, nonwoven 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. When the separator is a multi-layer composite film, the separator of this application does not contain a PVDF coating.

[0147] In some embodiments, the housing 3 of the lithium-ion battery 10 can be part of the vehicle's chassis structure. For example, a portion of the housing 3 can be at least a part of the vehicle's floor, or a portion of the housing 3 can be at least a part of the vehicle's crossbeams and longitudinal beams.

[0148] In some embodiments, the lithium-ion battery 10 may be located in an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0149] In some embodiments, the lithium-ion battery 10 may also include other components. For example, the lithium-ion battery 10 may also include a busbar component, which can be used to realize electrical connections between multiple battery cells 20, such as in parallel, series, or mixed connections. Specifically, the busbar component can realize electrical connections between battery cells 20 by connecting to the electrode terminals 21 of the battery cells 20; or, the busbar component can also realize electrical connections between battery cells 20 by connecting to other components of the battery cells 20. The busbar component can be fixed to corresponding components of the battery cells 20 by welding, for example, by welding to electrode terminals, sealing structures, or housings, etc., and the embodiments of this application are not limited thereto.

[0150] The battery cells 20 can be directly assembled into a lithium-ion battery 10, or they can be first assembled into a battery module, and then multiple battery modules can be assembled into a lithium-ion battery 10.

[0151] [Electrical appliances]

[0152] This application provides an electrical device including the lithium-ion battery described in the above embodiments.

[0153] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0154] This application provides an electrical device, which is a vehicle.

[0155] The vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. The vehicle's interior can house a motor, a controller, and a lithium-ion battery 10. The controller is used to control the lithium-ion battery 10 to power the motor. For example, the lithium-ion battery 10 can be located at the bottom, front, or rear of the vehicle. The lithium-ion battery 10 can be used to power the vehicle; for example, it can serve as the vehicle's operating power source for the vehicle's electrical system, such as meeting the power requirements for starting, navigation, and operation. In another embodiment of this application, the lithium-ion battery 10 can not only serve as the vehicle's operating power source but also as its driving power source, replacing or partially replacing gasoline or natural gas to provide driving power for the vehicle.

[0156] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0157] [Examples and Comparative Examples]

[0158] Example 1

[0159] (1) Preparation of negative electrode sheet

[0160] Artificial graphite (anode active material), acetylene black (conductive agent), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethyl cellulose (CMC-Na) (thickener) were dissolved in deionized water at a mass ratio of 96:1.5:1.5:1.0 and thoroughly mixed to prepare a cathode slurry. The cathode slurry was then coated onto copper foil (anode current collector), and subsequently dried, cold-pressed, and slit to obtain the cathode sheet.

[0161] (2) Preparation of positive electrode sheet

[0162] The positive electrode active material, the binder polyvinylidene fluoride (PVDF), and the conductive agent (acetylene black) are mixed evenly at a mass ratio of 97.5:1.5:1 and dissolved in the solvent N-methylpyrrolidone (NMP). After thorough stirring and mixing, a positive electrode slurry is prepared. The positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0163] (3) Preparation of battery cells

[0164] The positive electrode, separator, and negative electrode are stacked and wound in sequence to obtain an electrode assembly. The electrode assembly is placed in a housing, electrolyte is added, and after processes such as encapsulation, settling, formation, and aging, a battery cell 20 is obtained.

[0165] The electrolyte contained a lithium salt concentration of 1.1 M, with LiPF6 as the lithium salt and a carboxylic acid ester solvent content of W1 = 25%. The ionic conductivity of the electrolyte was measured to be σ = 12.8 mS / cm.

[0166] Twenty-seven battery cells 20 are arranged in a 3×3×3 configuration in the housing 3. Three cells are connected in parallel to form a battery string, and the three battery strings are connected in series. A thermal management component 40 is attached to the bottom wall of the 27 battery cells 20. The flow channels 41 in the thermal management component 40 are distributed as shown in Figure 6, forming a lithium-ion battery 10.

[0167] The lithium-ion battery 10 was subjected to fast-charge cycle testing at room temperature (25℃-30℃), and the test conditions are detailed in the test method section below. During the first cycle of the lithium-ion battery 10, the temperature change curve at the geometric center of the surface with the largest area of ​​the battery cell 20 was measured using an infrared thermometer. The temperature T1 of the geometric center of the surface with the largest area of ​​the battery cell 20 with the highest temperature when the lithium-ion battery is charged to 80% SOC, and the temperature T2 of the end cap center of the battery cell 20 with the lowest temperature, were taken, and ΔT = T1 - T2 was obtained.

[0168] Example 2-3

[0169] Compared with Example 1, the difference is that thermal management components 40 with different flow channel distributions can be used, resulting in different measured ΔT values.

[0170] Example 4

[0171] Compared with Example 1, the difference is that the sidewalls of the battery cells 20 arranged in the 1×1×1 position are covered with thermal insulation cotton with a thermal conductivity of about 0.040W / mK.

[0172] Example 5

[0173] Compared with Example 1, the difference is that the sidewalls of the battery cells 20 arranged in the 2×2×2 position are also covered with thermal management components 40.

[0174] Example 6

[0175] Compared with Example 1, the difference is that the sidewalls of the battery cells 20 arranged in the 1×1×1 position are covered with thermal insulation cotton with a thermal conductivity of about 0.04 W / mK, and the sidewalls of the battery cells 20 arranged in the 2×2×2 position are also covered with thermal management components 40.

[0176] Comparative Example 1

[0177] Compared with Example 1, Comparative Example 1 did not use the thermal management component 40 designed in this application, and the measured ΔT was not in the range of 0℃~8℃.

[0178] Product parameters and performance parameters of Examples 1-6 and Comparative Example 1.

[0179] Table 1: Product parameters and performance parameters of Examples 1-6 and Comparative Example 1

[0180] In Table 1, “△T” represents the temperature difference between the battery cell 20 with the highest temperature and the battery cell 20 with the lowest temperature when the lithium-ion battery 10 is charged to 80% SOC; “Whether to add thermal management components” indicates whether to add thermal management components at the battery cells 20 arranged in the 2×2×2 position; “Whether to add heat insulation components” indicates whether to add heat insulation components at the battery cells 20 arranged in the 1×1×1 position; “Number of cycles” indicates the number of cycles corresponding to the lithium-ion battery 10 being charged to 80% SOH in the fast charging cycle test.

[0181] It should be understood that for the 27 battery cells arranged in a 3×3×3 configuration, the battery cell 20 with the worst heat dissipation and the highest temperature during fast charging can be considered as the battery cell 20 arranged in the 2×2×2 position. In other words, in the above embodiments and comparative examples, the battery cell 20 arranged in the 2×2×2 position can represent the first battery cell 21. The battery cell 20 with better heat dissipation and the lowest temperature during fast charging may be the battery cells 20 arranged in the 1×1×1, 1×3×1, 1×1×3, 3×1×1, 1×3×3, 3×1×3, 3×3×1, and 3×3×3 positions. The temperature and temperature change of the battery cells in these eight positions can be considered to be almost the same. Similarly, in the above embodiments and comparative examples, the battery cell 20 arranged in the 1×1×1 position can represent the second battery cell 22.

[0182] Comparative analysis of the embodiments and comparative examples shows that in Embodiments 1-6, the temperature uniformity of the individual battery cells 20 within the lithium-ion battery 10 is good, and the temperature difference between the first battery cell 21 and the second battery cell 22 is controlled within the range of 0℃-8℃, exhibiting better cycle performance than Comparative Example 1 during fast charging cycles. In contrast, in Comparative Example 1, the temperature difference between the first battery cell 21 and the second battery cell 22 is too large, resulting in a significant deterioration in the cycle performance of the lithium-ion battery 10. This demonstrates that controlling the temperature difference between the first battery cell 21 and the second battery cell 22 within a suitable range helps improve the cycle performance of fast-charging lithium-ion batteries.

[0183] The analysis and comparison of Examples 1-3 show that the smaller ΔT is, the better the temperature uniformity of the battery cell 20 and the better the cycle performance of the lithium-ion battery 10.

[0184] The analysis and comparison of Examples 1-4 show that by adding a heat insulation component at the second battery cell 22, the temperature difference ΔT between the first battery cell 21 and the second battery cell 22 can be further reduced, thereby further improving the cycle performance of the lithium-ion battery 10.

[0185] The analysis and comparison of Examples 1-3 and 5 show that by adding a thermal management component at the first battery cell 21, the temperature difference ΔT between the first battery cell 21 and the second battery cell 22 can be further reduced, thereby further improving the cycle performance of the lithium-ion battery 10.

[0186] Analysis and comparison of Examples 4-6 show that adding a thermal management component at the first battery cell 21 and adding a heat insulation component at the second battery cell 22 can further improve the cycle performance of the lithium-ion battery 10.

[0187] It should be understood that selecting thermal management components 40 with different flow channel distributions, adding thermal management components 40, and adding insulation components are all methods to keep ΔT within a suitable range. The above embodiments and comparative examples use the selection of thermal management components 40 that meet design requirements as examples, but do not mean that selecting thermal management components 40 that meet design requirements is a necessary condition to keep ΔT within the range of 0℃-8℃.

[0188] The following is a brief description of the testing methods for the physicochemical and performance parameters involved in the embodiments of this application. It should be understood that the following testing methods are only examples, and other testing methods known in the art can also be used for testing.

[0189] 1. Charging time test method

[0190] The battery cell 20 to be tested is placed on a charging pile with a charging power of 120W. The state of charge of the battery cell 10 is adjusted to 10% SOC (10% of the rated capacity). Then it is charged on the charging pile. The time taken for the lithium-ion battery to be charged to 80% SOC (80% of the rated capacity) is recorded, which is the charging time of the battery cell 20.

[0191] 2. Test methods for electrolyte conductivity

[0192] The test method follows HG / T 4067-2015. The conductivity of the electrolyte to be tested is measured using a conductivity meter: Take about 100 ml of the sample to be tested in a dry, clean, corrosion-resistant sample bottle, seal it and place it in a constant temperature water bath at 25±0.5℃. When the temperature of the sample to be tested is constant, replace the cap of the sample bottle with a rubber stopper with an electrode inserted. When the temperature is within the range of 25±0.5℃, read the data, which is the conductivity of the sample to be tested.

[0193] 3. Test methods for temperature and temperature difference of individual battery cells

[0194] It should be understood that the temperature of the battery cell 20 can be measured using any possible method. An infrared thermometer is used as an example below.

[0195] The infrared thermometer probe is aligned with the geometric center of the largest surface area of ​​the battery cell 20. The lithium-ion battery 10 is then charged, following a cycle performance testing method. The infrared thermometer records the temperature change of the battery cell 20 during charging. The difference between the temperatures T1 of the first battery cell 21 and T2 of the second battery cell 22 at the same moment is used to obtain ΔT.

[0196] 4. Test method for cross-sectional area of ​​flow channel

[0197] A CT scan is performed on the thermal management component 40, and the scanned images are tested. Based on the scanned images, the shape and dimensions of the thermal management component 40 and its flow channel 41 can be measured. For a regularly shaped flow channel 41, its cross-sectional area can be calculated using the area calculation formula for regularly shaped channels. For an irregularly shaped flow channel, its cross-sectional area can be calculated using the area calculation formula for regularly shaped channels after fitting the irregular shape into a regularly shaped shape on a computer.

[0198] 5. Test method for the mass content of solvent (carboxylic acid ester)

[0199] The reference standard GB / T 9722-2006 specifies the quantitative analysis of solvent content in electrolytes using organic gas chromatography (GC).

[0200] 6. Cyclic performance testing methods

[0201] At 25±5℃, a fully discharged battery cell was charged at a constant current of 0.33C to 10% SOC, then charged at 5C from 10% SOC to 45% SOC, then charged 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, 2.9C from 75% SOC to 80% SOC, and 0.33C from 80% SOC to 100% SOC. After resting for 30 minutes, it was discharged at 0.33C to 2.8V, and the discharge capacity C1 was recorded. This constitutes one charge-discharge cycle. The battery cell is subjected to multiple fast-charging cycles until its discharge capacity decays to 0.8C1 (i.e., the battery health status reaches 80% SOH), and the number of fast-charging cycles for that battery cell is measured.

[0202] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A lithium-ion battery, characterized by, The time t for charging the lithium-ion battery from 10% SOC to 80% SOC satisfies: t≤20min, and the lithium-ion battery comprises multiple battery cells; The battery cell includes a positive electrode active material, which includes a lithium-containing transition metal oxide. The plurality of battery cells include a first battery cell and a second battery cell. During the charging process of the lithium-ion battery, the temperature T1 at the geometric center of the surface with the largest area of ​​the first battery cell and the temperature T2 at several centers of the surface with the largest area of ​​the second battery cell at the same time satisfy: 0℃≤△T≤8℃.

2. The lithium-ion battery according to claim 1, characterized in that, The battery cell includes an electrolyte, and the ionic conductivity σ of the electrolyte satisfies: 9mS / cm≤σ≤25mS / cm.

3. The lithium-ion battery according to claim 1 or 2, characterized in that, The lithium-ion battery includes a thermal management component attached to at least one surface of the battery cell. The thermal management component includes a flow channel for containing fluid to regulate the temperature of the battery cell.

4. The lithium-ion battery according to claim 3, characterized in that, The cross-sectional area of ​​the flow channel through the first battery cell is greater than the cross-sectional area of ​​the flow channel through the second battery cell.

5. The lithium-ion battery according to claim 3 or 4, characterized in that, The contact area between the first battery cell and the thermal management component is greater than the contact area between the second battery cell and the thermal management component.

6. The lithium-ion battery according to any one of claims 1-5, characterized in that, The number of flow channels flowing through the first battery cell is greater than the number of flow channels flowing through the second battery cell.

7. The lithium-ion battery according to any one of claims 1-6, characterized in that, The lithium-ion battery includes a heating element, which is attached to at least one surface of the second battery cell.

8. The lithium-ion battery according to any one of claims 1-7, characterized in that, The lithium-ion battery includes a heat-insulating component, which is attached to at least one surface of the second battery cell.

9. The lithium-ion battery according to any one of claims 1-8, characterized in that, The capacity C of the battery cell satisfies: 60Ah≤C≤200Ah.

10. The lithium-ion battery of any one of claims 1-9, wherein, The electrolyte includes a carboxylic acid ester solvent; the carboxylic acid ester solvent includes at least one of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl acrylate, and ethyl acrylate.

11. The lithium-ion battery of claim 10, wherein, Based on the total mass of the electrolyte, the mass fraction W1 of the carboxylic acid ester solvent satisfies: 5wt% ≤ W1 ≤ 80wt%.

12. The lithium-ion battery according to any one of claims 1-11, characterized in that, Based on the total mass of the electrolyte, the mass content W2 of the carboxylic acid ester solvent satisfies: 10%wt ≤ W2 ≤ 40wt.

13. The lithium-ion battery according to any one of claims 1-12, characterized in that, The lithium transition metal oxide comprises Li x Ni (1-y-z) Co y M z O 2-b ; Wherein, M includes at least one element selected from Mn, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, Nb and Zr, 0 < x ≤ 1.2, 0.18 ≤ y ≤ 0.25, 0 ≤ z ≤ 0.2, 1 - yz ≥ 0.55, and 0 ≤ b ≤ 0.

2.

14. The lithium-ion battery according to any one of claims 1-13, characterized in that, The electrolyte includes carbonate solvents, which include at least one of ethylene carbonate, propylene carbonate, and ethyl methyl carbonate.

15. The lithium-ion battery according to any one of claims 1-14, characterized in that, The electrolyte includes an electrolyte salt, which includes LiFSI.

16. An electrical appliance, characterized in that, The electrical device includes the lithium-ion battery according to any one of claims 1-15.

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