Battery and electric apparatus

Abstract

A battery and an electric apparatus. The battery comprises a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode active material layer, the positive electrode active material layer comprising a positive electrode active material and a lithium-supplementing agent, and the content of nickel in 1 mol of the positive electrode active material being 0.8 mol to 1 mol; and the negative electrode sheet comprises a negative electrode active material layer, the negative electrode active material layer comprising a negative electrode active material, and the negative electrode active material comprising a silicon-based material. The present application can improve the capacity of the battery and reduce the resistance to the intercalation of active metal ions during charging, thereby improving the energy density and fast-charging performance of the battery.

Description

Batteries and electrical devices

[0001] Priority information

[0002] This application claims priority and benefit to patent application 202410946573.7, filed with the China National Intellectual Property Administration on July 15, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application belongs to the field of batteries, specifically relating to a battery and an electrical device. Background Technology

[0004] Rechargeable batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other fields. As the application scope of batteries becomes increasingly wide, the performance requirements for rechargeable batteries are becoming more stringent, with higher demands placed on battery energy density and fast-charging performance. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides a battery that aims to improve the energy density and fast charging performance of the battery.

[0006] To achieve the above objectives, the first aspect of this application proposes a battery comprising a positive electrode and a negative electrode. The positive electrode comprises a positive active material layer, which includes a positive active material and a lithium supplement, wherein 1 mol of the positive active material contains 0.8 mol-1 mol of nickel. The negative electrode comprises a negative active material layer, which includes a negative active material, which is a silicon-based material.

[0007] This application includes at least the following beneficial effects: In the battery of this application, controlling the nickel content in the positive electrode active material and adding silicon-based material to the negative electrode active material, and adding lithium supplementer to the positive electrode, can improve the battery capacity, reduce the resistance to the intercalation of active metal ions during the charging process, and thus improve the energy density and fast charging performance of the battery.

[0008] In some embodiments, the nickel content in 1 mol of the positive electrode active material is 0.88 mol-0.95 mol. This can increase the battery's energy density and improve fast-charging performance.

[0009] In some embodiments, the ratio of the capacity of the negative electrode to the capacity of the positive electrode is N / P, where N / P = 1.02-1.08. This can increase the battery's energy density and improve fast-charging performance.

[0010] In some embodiments, the specific capacity of the positive electrode active material is 200 mAh / g-250 mAh / g. This can increase the battery's energy density and improve fast-charging performance.

[0011] In some embodiments, the mass percentage of the positive electrode active material is 96.5%-99.5% based on the total weight of the positive electrode active material layer. This can increase the battery's energy density and improve fast-charging performance.

[0012] In some embodiments, the areal density of the positive electrode active material layer is 0.347 g / 1540.25 mm. 2 -0.547g / 1540.25mm 2 This can increase the battery's energy density and improve fast charging performance.

[0013] In some embodiments, the positive electrode active material comprises a lithium-nickel-containing transition metal oxide. This can increase the battery's energy density and improve fast-charging performance.

[0014] In some embodiments, the chemical formula of the positive electrode active material includes: Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y ,

[0015] Where x is 0.2-1.2, a is 0.8-1, b is 0-0.15, c is 0-0.15, d is 0-0.02, y is 0-0.1, M includes at least one of Zr, Y, Al, Ti, W, Sr, Ta, Sb, Nb, Na, K, Ca, or Ce, and A includes at least one of N, F, S, or Cl. This can improve the battery's energy density and enhance fast-charging performance.

[0016] In some embodiments, the volume average particle size Dv50 of the positive electrode active material is 3 μm-16 μm. This can increase the battery's energy density and improve fast-charging performance.

[0017] In some embodiments, the positive electrode active material comprises a first particle and a second particle, wherein the first particle has a volume average particle size Dv50 of 2 μm-25 μm, and the second particle has a volume average particle size Dv50 of 0.65 μm-10 μm. This can improve the battery's energy density and enhance fast-charging performance.

[0018] In some embodiments, the lithium replenishing agent includes at least one selected from Li5V2(PO4)3, LiVPO4F, LiNiO2, Li6CoO4, Co-Li2O, Co-Li2S, Li3N, Li2O, Li5FeO4, Li2O2, C2O4Li2, Li2OHCl, Li2CuO2, LiCoO2, or Li3ON. This can improve the battery's energy density and enhance fast-charging performance.

[0019] In some embodiments, the lithium supplement includes at least one of LiNiO2, Li6CoO4, Co-Li2O, Li2O, Li5FeO4, Li2O2, C2O4Li2, Li2OHCl, Li2CuO2, LiCoO2, or Li3ON.

[0020] In some embodiments, the mass ratio of the positive electrode active material to the lithium replenishing agent is (19-99):1. This can improve the battery's energy density and enhance fast-charging performance.

[0021] In some embodiments, the specific capacity of the negative electrode active material is 600 mAh / g-2200 mAh / g. This can increase the battery's energy density and improve fast-charging performance.

[0022] In some embodiments, the silicon-based material includes a silicon-carbon composite material, the silicon-carbon composite material including a three-dimensional network cross-linked pore structure and silicon nanoparticles, at least a portion of the silicon nanoparticles being disposed in the three-dimensional network cross-linked pore structure.

[0023] In some embodiments, the mass percentage of silicon is 5%-40% based on the total mass of the negative electrode active material. This can increase the energy density of the battery and improve fast charging performance.

[0024] In some embodiments, the mass percentage of silicon is 10%-30% based on the total mass of the negative electrode active material. This can increase the energy density of the battery and improve fast charging performance.

[0025] In some embodiments, the negative electrode sheet includes a negative electrode active material layer, the areal density of which is 0.06 g / 1540.25 mm². 2 -0.2g / 1540.25mm 2 This can increase the battery's energy density and improve fast charging performance.

[0026] In some embodiments, the negative electrode sheet includes a negative electrode active material layer, which comprises a negative electrode active material. Based on the total weight of the negative electrode active material layer, the mass percentage of the negative electrode active material is 92%-96.5%. This can improve the battery's energy density and enhance fast-charging performance.

[0027] In some embodiments, the battery further includes an electrolyte comprising lithium bisfluorosulfonylimide. This can increase the battery's energy density and improve fast-charging performance.

[0028] In a second aspect of this application, an electrical device is provided, including the battery described in the first aspect of this application.

[0029] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0030] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0031] Figure 1 is a schematic diagram of a battery according to one embodiment of this application.

[0032] Figure 2 is an exploded view of the battery according to one embodiment of this application shown in Figure 1.

[0033] Figure 3 is a schematic diagram of a battery module according to one embodiment of this application.

[0034] Figure 4 is a schematic diagram of a battery pack according to one embodiment of this application.

[0035] Figure 5 is an exploded view of the battery pack of one embodiment of this application shown in Figure 4.

[0036] Figure 6 is a schematic diagram of an electrical device in which a battery is used as a power source according to an embodiment of this application.

[0037] Explanation of reference numerals in the attached drawings: 1. Battery cell; 11. Housing; 12. Electrode assembly; 13. Cover plate; 2. Battery module; 3. Battery pack; 31. Upper casing; 32. Lower casing.

[0038] Detailed description of the invention

[0039] The embodiments of the technical solution of this application are described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0040] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0041] 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 expected that ranges of 60-110 and 80-120 are also included. 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 "ab" 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.

[0042] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0043] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0044] 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.

[0045] Currently, judging from market trends, the application of rechargeable batteries is becoming increasingly widespread. Rechargeable batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace, among other fields.

[0046] As the application of rechargeable batteries becomes more widespread, the performance requirements for them are becoming increasingly stringent, such as the need for high energy density. Currently, to increase the energy density of rechargeable batteries, the design requires the use of high-nickel materials for the positive electrode active material and silicon-based materials for the negative electrode active material. However, while this approach improves the battery's energy density, silicon-based materials have a higher capacity than carbon-based materials and are prone to expansion during charging and discharging. Furthermore, silicon-based materials have low initial efficiency, and the first-cycle film formation consumes more lithium ions, resulting in a significant reduction in the lithium stripping capacity of the negative electrode during discharge. This also affects the fast-charging performance of batteries containing silicon, making it difficult to achieve both high energy density and fast-charging performance.

[0047] In the battery of this application, controlling the nickel content in the positive electrode active material and using silicon-based materials in the negative electrode active material can improve the battery capacity and thus increase the energy density. Addressing the issue of low initial efficiency and limited fast-charging performance of silicon-based materials, a lithium replenishing agent is added to the positive electrode active material layer. On one hand, during the first charge, lithium ions are released from the replenishing agent, increasing the lithium release capacity of the positive electrode during charging and providing sufficient capacity for the negative electrode, thereby increasing the lithium release capacity of the negative electrode during discharge and improving the battery's energy density. On the other hand, the lithium replenishing agent undergoes delithiation and structural shrinkage during charging, providing vacancies for the positive electrode film, increasing the porosity of the positive electrode sheet, reducing the resistance to lithium ion transport during subsequent charging, and improving the battery's fast-charging performance. In summary, the battery proposed in this application can simultaneously achieve both high energy density and fast-charging performance.

[0048] It is understandable that lithium replenishment agents are additives used in lithium secondary batteries. Their main function is to compensate for the lithium consumed by the solid electrolyte interface (SEI) layer formed on the surface of the negative electrode material during the initial charging (formation) process, thereby improving the battery's initial coulombic efficiency and total capacity. They are substances containing lithium.

[0049] It can be understood that silicon-based materials refer to materials containing silicon, including but not limited to at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.

[0050] The batteries disclosed in this application can be used in electrical devices that use batteries as a power source or in various energy storage systems that use batteries as energy storage elements. Electrical devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys may include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0051] The first aspect of this application discloses a battery comprising a positive electrode and a negative electrode. The positive electrode comprises a positive active material layer, which includes a positive active material and a lithium supplement, wherein 1 mol of the positive active material contains 0.8 mol-1 mol of nickel. The negative electrode comprises a negative active material layer, which includes a negative active material, which is a silicon-based material.

[0052] In this application, controlling the nickel content in the positive electrode active material and using silicon-based materials in the negative electrode active material can improve battery capacity and thus energy density. Addressing the issue of low initial efficiency and limited fast-charging performance of silicon-based materials, a lithium replenishing agent is added to the positive electrode active material layer. On one hand, during the first charge, lithium ions are released from the replenishing agent, increasing the lithium release capacity of the positive electrode during charging and providing sufficient capacity for the negative electrode, thereby improving the lithium release capacity of the negative electrode during discharge and increasing the battery's energy density. On the other hand, the lithium replenishing agent undergoes delithiation and structural shrinkage during charging, providing vacancies for the positive electrode film, increasing the porosity of the positive electrode, reducing the resistance to lithium ion transport during subsequent charging, and improving the battery's fast-charging performance. In summary, the battery proposed in this application can simultaneously achieve both high energy density and fast-charging performance.

[0053] In some embodiments of this application, the nickel content in 1 mol of the positive electrode active material is 0.8 mol-1 mol. For example, the nickel content in 1 mol of the positive electrode active material can be 0.85 mol-0.99 mol, 0.86 mol-0.98 mol, 0.87 mol-0.97 mol, 0.88 mol-0.96 mol, 0.89 mol-0.95 mol, 0.9 mol-0.94 mol, 0.91 mol-0.93 mol, etc. Controlling the nickel content in the positive electrode active material within the above range results in a higher nickel content, which can increase the battery capacity and thus improve the battery's energy density. In other embodiments of this application, the nickel content in 1 mol of the positive electrode active material is 0.88 mol-0.95 mol.

[0054] It is understood that "the nickel content in 1 mol of the positive electrode active material" is a well-known definition in the art and can be determined using methods known in the art, such as the following method (ICP testing):

[0055] 1. Weighing: Accurately weigh approximately 0.1g of the positive electrode active material into a 50ml polytetrafluoroethylene digestion tube.

[0056] 2. Add an appropriate amount of 1+1 aqua regia to each of the weighed sample digestion tubes. Cover the tubes and place them in a stainless steel reactor. Heat the reactor in an oven at 190 degrees Celsius for approximately 10 hours, then stop heating and allow it to cool.

[0057] 3. Transfer the cooled solution to a 25ml plastic volumetric flask, and finally dilute to volume with deionized water.

[0058] 4. Prepare standard test solutions. The standard solutions are national standard reference materials, and the concentration points of the curve are 0, 0.5, 1.0, 2.0, and 5.0 mg / L.

[0059] 5. Instrument testing: First, use the ICP-OES instrument to create a standard solution calibration curve, input the sample mass and volume, and then test the digested solutions in sequence. If the solution exceeds the curve range, dilute it before testing.

[0060] 6. Finally, the final content of the elements measured in each sample is determined by the spectrum, as well as the mass ratio of Li, Ni, Co (if any), Mn (if any), and M (if any), and then converted into the molar ratio of the above elements to obtain the test results.

[0061] In some embodiments of this application, the ratio of the capacity of the negative electrode to the capacity of the positive electrode is N / P, where N / P = 1.02-1.08. For example, N / P can be 1.02-1.07, 1.03-1.06, 1.04-1.05, etc. Specifically, N / P (Negative / Positive) is the ratio of the reversible areal capacity of the negative electrode to the reversible areal capacity of the positive electrode under the same operating conditions and in the same stage. Controlling N / P within the above range, a smaller N / P value can reduce the weight (i.e., areal density) of the negative electrode, reduce the resistance to the intercalation of active metal ions during charging, improve fast charging performance, and the smaller weight of the negative electrode can also reduce weight, thereby increasing the energy density of the battery. In other embodiments of this application, N / P = 1.025-1.08.

[0062] It is understood that "N / P" is a well-known definition in the art and can be determined using methods known in the art, for example, the following methods can be used for determination:

[0063] The following formula is used to calculate N / P: N / P = (specific capacity of negative electrode active material × mass percentage of negative electrode active material in negative electrode active material layer × areal density of negative electrode active material layer) / (specific capacity of positive electrode active material × mass percentage of positive electrode active material in positive electrode active material layer × areal density of positive electrode active material layer). The determination methods of each parameter in the formula are detailed below.

[0064] In some embodiments of this application, y = (specific capacity of negative electrode active material × areal density of negative electrode active material layer) / (specific capacity of positive electrode active material × areal density of positive electrode active material layer), y = 1.10-1.20. For example, y can be 1.10-1.19, 1.11-1.18, 1.13-1.16, 1.14-1.15, etc. Controlling the y value within the above range makes it easier to make N / P = 1.02-1.08, thereby achieving a balance between battery energy density and fast charging performance.

[0065] In some embodiments of this application, the specific capacity of the positive electrode active material is 200mAh / g-250mAh / g. For example, the specific capacity of the positive electrode active material can be 200mAh / g-249mAh / g, 210mAh / g-245mAh / g, 215mAh / g-240mAh / g, 220mAh / g-235mAh / g, 225mAh / g-230mAh / g, etc. It is understood that the specific capacity of the positive electrode active material refers to the capacity per unit of positive electrode active material. Controlling the specific capacity of the positive electrode active material within the above range is beneficial for obtaining a battery with the desired N / P range, which can increase the battery capacity and thus improve the battery's energy density. In other embodiments of this application, the specific capacity of the positive electrode active material is 205mAh / g-240mAh / g.

[0066] In this application, "specific capacity of the positive electrode active material" refers to the weighted specific capacity of both the positive electrode active material and the lithium supplement, while the lithium supplement itself does not contribute to the capacity. The "specific capacity of the positive electrode active material" can be measured using instruments and methods known in the art, such as the following test methods:

[0067] Test method: Button capacitance test

[0068] Test process:

[0069] 1. The positive electrode active material, (if lithium supplementation agent is present, it is combined with the positive electrode active material to form an active material), conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are added to N-methylpyrrolidone at a mass ratio of 97:1:2, and mixed and stirred for 5 hours to obtain a positive electrode slurry; then it is uniformly coated on the positive electrode current collector, and after drying, cold pressing and slitting, a positive electrode sheet is obtained.

[0070] 2. The above-mentioned positive electrode sheet, separator, and lithium sheet are punched into round sheets of a fixed size, and stacked in sequence in a glove box to obtain a bare button cell. Electrolyte is injected, and the cells are assembled to obtain a button cell. The battery is then sealed using a battery sealing machine.

[0071] 3. Charge and discharge tests are conducted based on the theoretical capacity of the battery. The theoretical capacity C = (weight of electrode sheet - weight of substrate) × proportion of positive electrode active material × specific capacity of positive electrode active material. The specific capacity is calculated according to the reference value before the test.

[0072] 4. Setting procedure on charging and discharging equipment: Charge the button cell to the charging cut-off voltage at 0.1C (where C represents the rated capacity of the battery cell); let it stand at 25℃ for 0.5h; discharge the battery cell to the discharge cut-off voltage at 0.1C, and record the total discharge capacity C0 of the battery cell.

[0073] 5. The specific capacity of the positive electrode active material is calculated as C0 / ((electrode weight - substrate weight) × positive electrode active material ratio).

[0074] In some embodiments of this application, the positive electrode sheet includes a positive electrode active material layer, which includes the positive electrode active material. Based on the total weight of the positive electrode active material layer, the mass percentage of the positive electrode active material is 96.5%-99.5%. For example, based on the total weight of the positive electrode active material layer, the mass percentage of the positive electrode active material can be 96.5%-99.4%, 97%-99%, 97.5%-98.5%, 98%-98.5%, etc. Therefore, a high content of positive electrode active material in the positive electrode active material layer can increase the battery capacity, thereby increasing the battery's energy density. Furthermore, it can reduce the weight of the positive electrode sheet, decrease the resistance to active metal ion insertion during charging, improve fast charging performance, and the smaller weight of the positive electrode sheet can also reduce weight, thus increasing the battery's energy density. In other embodiments of this application, based on the total weight of the positive electrode active material layer, the mass percentage of the positive electrode active material is 97%-98.9%.

[0075] In this application, "the mass percentage of the positive electrode active material based on the total weight of the positive electrode active material layer" is a well-known definition in the art and can be tested using instruments and methods known in the art, for example, the test method is as follows:

[0076] Digestion method for determining mass percentage:

[0077] 1. Take the positive electrode sheet and empty aluminum foil (if the positive current collector is made of other materials, then replace them accordingly) and punch them to 154.025mm. 2 30 small round pieces each;

[0078] 2. The mass of weighing bottle A and filter membrane B is taken as M0; the weight of a single aluminum foil is taken as M1; the positive electrode sheet that has been punched in the conical flask is taken as M2, and concentrated hydrochloric acid is added to the conical flask and heated for digestion;

[0079] 3. Filter out the digested solution portion, pour the filter residue on the filter membrane back into the conical flask, and add concentrated hydrochloric acid to continue digestion; repeat the filtration steps, transfer the filter residue and filter membrane B to weighing bottle A, and place it in an 85℃ drying oven to bake for 4 hours; after cooling for 0.5 hours, weigh the dried filter residue, filter membrane and weighing bottle to obtain the mass M3;

[0080] 4. Calculation: M (Loading) is the mass of the remaining material after digesting 30 small discs, = M3 - M0

[0081] M (Coating) is the total coating weight on 30 small discs, = M2 - M1 × n (n = 30);

[0082] The mass percentage of the positive electrode active material, Wt%, is calculated as follows: (1 - (M3 - M0) / (M2 - M1 × n)) × 100%.

[0083] In some embodiments of this application, the positive electrode sheet includes a positive active material layer, the positive active material layer includes the positive active material, and the areal density of the positive active material layer is 0.347 g / 1540.25 mm. 2 -0.547g / 1540.25mm 2 For example, the areal density of the positive electrode active material layer can be 0.347 g / 1540.25 mm. 2 -0.540g / 1540.25mm 2 0.35g / 1540.25mm 2 -0.5g / 1540.25mm 2 0.4g / 1540.25mm 2 -0.45g / 1540.25mm 2 Specifically, controlling the areal density of the positive electrode active material layer within the above-mentioned range is beneficial for obtaining a battery with the required N / P range. It can reduce the weight of the negative electrode sheet, reduce the resistance to the insertion of active metal ions during charging, improve fast charging performance, and the smaller weight of the negative electrode sheet can play a role in weight reduction, thereby increasing the energy density of the battery.

[0084] In this application, "the areal density of the positive electrode active material layer" is a well-known definition in the art and can be tested using instruments and methods known in the art, for example, the test method is as follows:

[0085] The surface density per unit area of ​​the positive electrode active material layer is m / S, where m represents the weight of the film layer and S represents the area of ​​the film layer. m can be obtained by subtracting the weight of the current collector from the weight of the electrode. The length and width of the film layer can be measured with a ruler.

[0086] In some embodiments of this application, the positive electrode active material comprises a lithium-nickel-containing transition metal oxide. This can increase the battery's energy density and improve fast-charging performance.

[0087] In some embodiments of this application, the chemical formula of the positive electrode active material includes: Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y ,

[0088] Where x is 0.2-1.2, a is 0.8-1, b is 0-0.15, c is 0-0.15, d is 0-0.02, y is 0-0.1, M includes at least one of Zr, Y, Al, Ti, W, Sr, Ta, Sb, Nb, Na, K, Ca or Ce, and M' includes at least one of N, F, S or Cl. For example, x can be 0.2-1.1, 0.4-1, 0.5-0.8, etc.; a can be 0.85-0.99, 0.86-0.98, 0.87-0.97, 0.88-0.96, 0.89-0.95, 0.9-0.94, 0.91-0.93, etc.; b can be 0.01-0.14, 0.03-0.12, 0.05-0.1, 0.07-0.09, etc.; and c can be 0. The positive electrode active material with the above chemical formula can have a high nickel content, which can further improve the battery capacity and thus increase the energy density.

[0089] It is understandable that Li deintercalation and consumption occur during the charging and discharging process of a battery, and the molar content of Li varies when the battery is discharged to different states. In the examples of the above-mentioned positive electrode active materials in this application, the molar content of Li refers to the initial state of the material, that is, the state before feeding. After the positive electrode active material is applied to the battery system and undergoes charge and discharge cycles, the molar content of Li will change.

[0090] In the examples of positive electrode active materials for lithium-ion batteries in this application, the molar content of O is only a theoretical state value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate.

[0091] In some embodiments of this application, the volume average particle size Dv50 of the positive electrode active material is 3μm-16μm. For example, it can be 3μm-15μm, 5μm-13μm, 8μm-10μm, etc., thereby increasing the compaction density of the positive electrode active material, which in turn can improve the energy density of the battery and improve fast charging performance.

[0092] It is understood that the volume average particle size Dv50 of the positive electrode active material refers to the particle size corresponding to a cumulative volume distribution percentage of 50%. The volume average particle size Dv50 of the positive electrode active material can be determined using methods known in the art, for example, it can be determined by the following methods:

[0093] Referring to standard GB / T 19077-2016, the volume average particle size Dv50 of the positive electrode active material was tested using a laser particle size analyzer (e.g., Malvern Master Sizer 3000).

[0094] In some embodiments of this application, the positive electrode active material includes a first particle and a second particle. The volume average particle size (Dv50) of the first particle is 2 μm-25 μm, and the volume average particle size (Dv50) of the second particle is 0.65 μm-10 μm. For example, the volume average particle size (Dv50) of the first particle can be 2 μm-24 μm, 5 μm-20 μm, 10 μm-15 μm, etc., and the volume average particle size (Dv50) of the second particle can be 0.65 μm-9.9 μm, 1 μm-9 μm, 2 μm-8 μm, 3 μm-7 μm, 4 μm-6 μm, etc. Specifically, the positive electrode active material uses a mixture of two particle sizes, containing both large and small particles, which can increase the compaction density of the positive electrode active material, thereby increasing the energy density of the battery. In addition, the small particles fill the gaps between the large particles, playing a buffering role, which can reduce the breakage of the large particles and improve the stability of the battery. In some other embodiments of this application, the volume average particle size Dv50 of the first particle is 2.5μm-23μm, and the volume average particle size Dv50 of the second particle is 1.2μm-8.5μm.

[0095] In some embodiments of this application, the lithium replenishing agent includes at least one of Li5V2(PO4)3, LiVPO4F, LiNiO2, Li6CoO4, Co-Li2O, Co-Li2S, Li3N, Li2O, Li5FeO4, Li2O2, C2O4Li2, Li2OHCl, Li2CuO2, LiCoO2, or Li3ON. Specifically, during the first charge, all or part of the lithium ions in the lithium replenishing agent are extracted, increasing the lithium extraction capacity of the positive electrode during charging and providing sufficient consumption margin for the negative electrode, thereby increasing the lithium extraction capacity of the negative electrode during discharge and thus improving the energy density of the battery. In addition, the lithium replenishing agent completes delithiation and structural shrinkage during charging, providing vacancies for the positive electrode and reducing the resistance to lithium ion extraction during subsequent charging, thereby improving the fast charging performance of the positive electrode side of the battery. In some other embodiments of this application, the lithium replenishing agent includes at least one of LiNiO2, Li6CoO4, Co-Li2O, Li2O, Li5FeO4, Li2O2, C2O4Li2, Li2OHCl, Li2CuO2, LiCoO2, or Li3ON. Specifically, in addition to the above-mentioned effects, the lithium replenishing agent may participate in the reaction on the surface of the negative electrode during the charging process, making the negative electrode film loose and reducing the negative electrode film resistance, thereby making it easier for lithium ions to insert and extract, and further improving the fast charging performance of the lithium-ion battery.

[0096] In some embodiments of this application, the mass ratio of the positive electrode active material to the lithium replenisher is (19-99):1. For example, the mass ratio of the positive electrode active material to the lithium replenisher can be (19-98):1, (20-90):1, (30-80):1, (40-70):1, (50-60):1, etc. Specifically, controlling the mass ratio of the positive electrode active material to the lithium replenisher within the above range can reduce the insignificant lithium replenishment caused by insufficient lithium replenisher, which is sufficient to improve the energy density and fast charging performance of the battery. It can also reduce the mass occupied by the lithium replenisher on the positive electrode active material caused by excessive lithium replenisher, resulting in a higher battery energy density.

[0097] In this application, "the mass ratio of the positive electrode active material to the lithium supplementer" is a well-known definition in the art and can be tested using instruments and methods known in the art, for example, the test method is as follows:

[0098] Burning powder + ICP test (assuming it is lithium ferrite):

[0099] Take one cathode electrode and place it in a muffle furnace at 600℃ for 2 hours. After cooling, take it out and grind the powder in a mortar. Send the powder to ICP test to determine the content of elements such as Ni, Co, Mn, and Fe. Fe element is only present in lithium ferrite. Calculate the material percentage based on the element percentage.

[0100] In some embodiments of this application, the negative electrode sheet includes a negative electrode active material, and the specific capacity of the negative electrode active material is 600mAh / g-2200mAh / g. For example, the specific capacity of the negative electrode active material can be 600mAh / g-2100mAh / g, 600mAh / g-1100mAh / g, 700mAh / g-1000mAh / g, 800mAh / g-1000mAh / g, 900mAh / g-1000mAh / g, etc. Specifically, controlling the specific capacity of the negative electrode active material within the above range is beneficial to obtaining a battery with an N / P value between 1.02 and 1.08, enabling the battery to balance energy density and fast charging performance.

[0101] In this application, "specific capacity of negative electrode active material" is a well-known definition in the art and can be tested using instruments and methods known in the art, such as the following test method:

[0102] Test method: Button capacitance test

[0103] Test process:

[0104] 1. The negative electrode active material graphite, the negative electrode active material silicon carbide, the conductive agent carbon black, carbon nanotubes (CNT), the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) are added to deionized water in a weight ratio of 60.48:34.02:1:0.375:2.8:1.325 and mixed and stirred for 4 hours to obtain a negative electrode slurry. The slurry is uniformly coated on the negative electrode current collector, dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0105] 2. The negative electrode sheet, separator, and lithium sheet are punched into round sheets of a fixed size, and stacked in sequence in a glove box to obtain a bare button cell. Electrolyte is injected, and the cells are assembled to obtain a button cell. The battery is then sealed using a battery sealing machine.

[0106] 3. Charge and discharge tests are conducted based on the theoretical capacity of the battery. The theoretical capacity C = (weight of electrode sheet - weight of substrate) × proportion of negative electrode active material × specific capacity of negative electrode active material. The specific capacity is calculated according to the reference value before the test.

[0107] 4. Setting procedure on charging and discharging equipment: Discharge the button cell to the discharge cutoff voltage at 0.1C (where C represents the rated capacity of the battery cell); let it stand at 25℃ for 0.5h; charge the battery cell to the charging cutoff voltage at 0.1C, and record the charging capacity C1 discharged by the battery cell;

[0108] 5. Obtain the specific capacity of the negative electrode = C1 / ((electrode weight - substrate weight) × proportion of negative electrode active material).

[0109] In some embodiments of this application, the negative electrode sheet includes a negative electrode active material, which includes a silicon-based material. Specifically, silicon-based materials have a high theoretical capacity, and when combined with the high nickel content positive electrode active material of the embodiments of this application, the battery can have a high energy density. In addition, using high-capacity silicon-based materials can reduce the coating thickness of the negative electrode sheet, shorten the transport path of active metal ions (such as lithium ions), and improve the fast-charging performance of the battery.

[0110] Furthermore, since silicon-based materials have a lower initial efficiency, the initial efficiency of the negative electrode is also lower, thereby reducing the overall initial efficiency of the battery. The loss of lithium ions from the positive electrode is also greater. By using silicon-based materials in combination with the lithium replenishing agent and the positive electrode active material with high nickel content in the embodiments of this application, it is possible to achieve high energy density of the battery and make up for the defect of silicon-based materials being prone to loss of active metal ions, thereby achieving a balance between battery energy density and fast charging performance.

[0111] In some embodiments of this application, the mass percentage of silicon, based on the total mass of the negative electrode active material, is 5%-40%. For example, it could be 5%-39%, 10%-30%, 20%-30%, etc. Specifically, carbon has a layered structure that facilitates lithium-ion intercalation and exhibits low lithium potential, high initial efficiency, and good cycle stability. Using carbon together with silicon as the negative electrode active material, and controlling their ratio within the aforementioned range, can balance the battery's energy density, fast-charging performance, and cycle performance. In other embodiments, the mass percentage of silicon, based on the total mass of the negative electrode active material, is 10%-30%.

[0112] In this application, "the mass percentage of silicon based on the total mass of the negative electrode active material" is a well-known definition in the art and can be tested using instruments and methods known in the art, such as the following test method:

[0113] Using ICP testing methods

[0114] 1. Weighing: Accurately weigh approximately 0.1g of the negative electrode material into a 50ml polytetrafluoroethylene digestion tube.

[0115] 2. Add appropriate amounts of inorganic acid (concentrated nitric acid + hydrofluoric acid) to the weighed sample digestion tubes. Cover the tubes and place them in a stainless steel reaction vessel. Heat the vessel in an oven at 190 degrees Celsius for about 10 hours, then stop heating and let it cool.

[0116] 3. Transfer the cooled solution to a 25ml plastic volumetric flask, and finally dilute to volume with deionized water.

[0117] 4. Prepare standard test solutions. The standard solutions are national standard reference materials, and the concentration points of the curve are 0, 0.5, 1.0, 2.0, and 5.0 mg / L.

[0118] 5. Instrument testing: First, use the ICP-OES instrument to create a standard solution calibration curve, input the sample mass and volume, and then test the digested solutions in sequence. If the solution exceeds the curve range, dilute it before testing.

[0119] 6. Finally, the final Si content in each sample is determined by the spectrum, and the test results are obtained.

[0120] It can be understood that carbon refers to materials whose components include carbon, and carbon materials include, but are not limited to, at least one of artificial graphite, natural graphite, soft carbon, and hard carbon.

[0121] It is understood that this application does not limit the ratio of silicon to carbon in silicon-carbon materials. The ratio of silicon to carbon can be determined with reference to the ratio of silicon-carbon materials commonly used in the art. In the embodiments of this application, the mass ratio of silicon to carbon is 1:1.

[0122] In some embodiments of this application, the negative electrode sheet includes a negative electrode active material layer, the areal density of which is 0.06 g / 1540.25 mm². 2 -0.2g / 1540.25mm 2 For example, the areal density of the negative electrode active material layer can be 0.06 g / 1540.25 mm. 2 -0.19g / 1540.25mm 2 0.08g / 1540.25mm 2 -0.15g / 1540.25mm 2 0.1g / 1540.25mm 2 -0.14g / 1540.25mm 2 0.11g / 1540.25mm 2 -0.13g / 1540.25mm 2 Therefore, controlling the areal density of the negative electrode active material layer within the above range is beneficial for obtaining a battery with an N / P value between 1.02 and 1.08, enabling the battery to balance energy density and fast charging performance. In some other embodiments of this application, the areal density of the negative electrode active material layer is 0.06 g / 1540.25 mm². 2 -0.177g / 1540.25mm 2 .

[0123] In this application, "the areal density of the negative electrode active material layer" is a well-known definition in the art and can be tested using instruments and methods known in the art, such as the following test method:

[0124] The surface density per unit area of ​​the negative electrode active material layer is given by m / S, where m represents the weight of the membrane layer and S represents the area of ​​the membrane layer. m can be obtained by subtracting the weight of the current collector from the weight of the electrode. The length and width of the membrane layer can be measured using a ruler.

[0125] In some embodiments of this application, the negative electrode sheet includes a negative electrode active material layer, which includes negative electrode active material. Based on the total weight of the negative electrode active material layer, the mass percentage of the negative electrode active material is 92%-96.5%. For example, based on the total weight of the negative electrode active material layer, the mass percentage of the negative electrode active material can be 92%-96.4%, 92.5%-96%, 93%-95.5%, 93.5%-95%, 94%-94.5%, etc. Specifically, controlling the content of negative electrode active material in the negative electrode active material layer within the above range is beneficial for obtaining a battery with an N / P value between 1.02 and 1.08. A high content of negative electrode active material in the negative electrode sheet can increase the battery capacity, thereby increasing the battery's energy density. In addition, it can reduce the weight of the negative electrode sheet, reduce the resistance to active metal ion insertion during charging, improve fast charging performance, and the small weight of the positive electrode sheet can also play a role in weight reduction, which can increase the battery's energy density. In some other embodiments of this application, the mass percentage of the negative electrode active material is 92.5%-94.9% based on the total weight of the negative electrode active material layer.

[0126] Typically, a battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active metal ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0127] In some embodiments of this application, the positive electrode sheet includes a positive current collector and a positive active material layer, the positive active material layer being disposed on at least one side of the positive current collector, and the positive active material layer including the positive active material.

[0128] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0129] In some embodiments of this application, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material 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 material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0130] In some embodiments, when the secondary battery is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art for lithium-ion batteries.

[0131] 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. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt 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 NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Examples of lithium 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 manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0132] During the charging and discharging process of a battery, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before material addition. After charge-discharge cycles, the molar Li content changes when the positive electrode active material is applied to the battery system.

[0133] In the examples of positive electrode active materials for lithium-ion batteries in this application, the molar content of O is only a theoretical state value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate.

[0134] In some embodiments of this application, when the positive electrode sheet is used in a sodium-ion battery, the positive electrode active material may also be a positive electrode active material known in the art for use in sodium-ion batteries. As an example, the positive electrode active material may include, but is not limited to, at least one of layered transition metal oxides, polyanionic compounds, and Prussian blue analogues.

[0135] Examples of the aforementioned layered transition metal oxides include:

[0136] Na 1-x Cu h Fe k Mn l M 1 m O 2-y M 1 Including at least one of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, or Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0137] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 Including at least one of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn, or Ba, 0 <z≤0.1;

[0138] Na a Li b Ni c Mn d Fe e O₂, where 0.67 < a ≤ 1, 0 < b < 0.2, 0 < c < 0.3, 0.67 < d + e < 0.8, and b + c + d + e = 1.

[0139] As examples of the above polyanion compounds, for example, the following can be listed:

[0140] A 1 f M 3 g (PO₄) i O j X 1 3-j , where A 1 includes at least one of H, Li, Na, K, or NH₄, M 3 includes at least one of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, or Zn, X 1 is at least one of F, Cl, or Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0141] Na n M 4 PO₄X 2 , where M 4 includes at least one of Mn, Fe, Co, Ni, Cu, or Zn, X 2 is at least one of F, Cl, or Br, 0 < n ≤ 2;

[0142] Na p M 5 q (SO₄)₃, where M 5 includes at least one of Mn, Fe, Co, Ni, Cu, or Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0143] Na s Mn t Fe 3-t (PO₄)₂(P₂O₇), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0144] As examples of the above Prussian blue analogs, for example, the following can be listed:

[0145] A u M 6 v [M 7 (CN)₆]w ·xH2O, where A includes H + , NH4 + , at least one of an alkali metal cation or an alkaline earth metal cation, M 6 and M 7 each independently includes at least one of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A includes H + , Li + , Na + , K + , NH4 + , Rb + , Cs + , Fr + , Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ or Ra 2+ at least one of, M 6 and M 7 each independently includes at least one cation of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn or W.

[0146] During the charge and discharge process of the battery, the insertion and extraction and consumption of Li or Na will occur, and the molar content of Li or Na is different when the battery is discharged to different states. In the listing of the positive electrode active material in this application, the molar content of Li or Na is the initial state of the material, that is, the state before feeding. When the positive electrode active material is applied to the battery system, after charge and discharge cycles, the molar content of Li or Na will change.

[0147] In the listing of the positive electrode active material in this application, the molar content of oxygen is only the theoretical state value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of oxygen will show fluctuations.

[0148] In some embodiments, the positive electrode active material layer may also optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0149] In some embodiments, the positive electrode film layer may also optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0150] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0151] In some embodiments of this application, the negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one side of the negative current collector.

[0152] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0153] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer 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 (copper, copper 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.).

[0154] In some embodiments, the negative electrode active material layer may optionally include a binder. The binder 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).

[0155] In some embodiments, the negative electrode active material layer may optionally include 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.

[0156] In some embodiments, the negative electrode active material layer may also optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0157] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0158] 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 completely solid.

[0159] In some embodiments of this application, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0160] In some embodiments of this application, when the battery is a lithium-ion battery, the electrolyte salt may include 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, or lithium tetrafluorooxalate phosphate.

[0161] In some other embodiments of this application, the electrolyte includes lithium bisfluorosulfonylimide (LiFSI). Specifically, the addition of LiFSI to the electrolyte has little impact on the battery energy density, but it can improve the conductivity of the electrolyte, thereby reducing the resistance of lithium ions when passing through the main body of the electrolyte during charging, allowing lithium ions to reach the negative electrode surface quickly, thereby improving the fast charging performance of the battery.

[0162] In some embodiments of this application, when the battery is a sodium-ion battery, the electrolyte salt may include at least one of sodium hexafluorophosphate, sodium difluorooxalate borate, sodium tetrafluoroborate, sodium dioxalate borate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethanesulfonate, or sodium bis(trifluoromethanesulfonyl)imide.

[0163] In some embodiments of this application, the solvent may include at least one selected from 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, ethylene glycol dimethyl ether, methyl ethyl sulfone, or diethyl sulfone.

[0164] In some embodiments of this application, 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.

[0165] This application does not impose any particular restrictions on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0166] In some embodiments, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The separator may 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 may be the same or different, without particular limitation.

[0167] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0168] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0169] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0170] This application does not impose any particular limitation on the shape of the battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 shows a square-structured battery cell 1 as an example.

[0171] In some embodiments, referring to FIG2, the outer packaging may include a housing 11 and a cover plate 13. The housing 11 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The housing 11 has an opening communicating with the receiving cavity, and the cover plate 13 can be placed over the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator can be formed into an electrode assembly 12 by a winding process or a stacking process. The electrode assembly 12 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 12. The number of electrode assemblies 12 contained in the battery cell 1 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0172] In some implementations, the batteries can be assembled into battery modules, and the number of batteries contained in a battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0173] Figure 3 shows a battery module 2 as an example. Referring to Figure 3, in battery module 2, multiple battery cells 1 can be arranged sequentially along the length of battery module 2. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 1 can be fixed in place using fasteners.

[0174] Optionally, the battery module 2 may also include a housing with a receiving space in which multiple battery cells 1 are received.

[0175] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0176] Figures 4 and 5 show an example battery pack 3. Referring to Figures 4 and 5, the battery pack 3 may include a battery box and multiple battery modules 2 disposed within the battery box. The battery box includes an upper box 31 and a lower box 32, with the upper box 31 covering the lower box 32 to form a closed space for accommodating the battery modules 2. The multiple battery modules 2 can be arranged in any manner within the battery box.

[0177] In addition, this application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0178] As the electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0179] Figure 6 shows an example of an electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0180] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can be powered by a battery.

[0181] 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.

[0182] Example 1

[0183] 1. Preparation of positive electrode sheet

[0184] LiNi, the positive electrode active material 0.93 Co0.06 Mn 0.01 O2, lithium supplementer C2O4Li2, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 95.06:1.94:1:2 with N-methylpyrrolidone and stirred for 5 hours to obtain a positive electrode slurry. This slurry was then uniformly coated onto a positive electrode current collector, dried, cold-pressed, and slit to obtain the positive electrode sheet and the positive electrode active material (LiNi). 0.93 Co 0.06 Mn 0.01 The specific capacity of the positive electrode active material layer (containing O2 and lithium supplement C2O4Li2) is 210.7 mAh / g, and the areal density of the positive electrode active material layer is 0.382 g / 1540.25 mm². 2 .

[0185] 2. Preparation of negative electrode sheet

[0186] Artificial graphite (anode active material), silicon-carbon material (silicon to carbon mass ratio 1:1), carbon black (conductive agent), carbon nanotubes (CNTs), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethyl cellulose (CMC) (thickener) were added to deionized water in a weight ratio of 66.15:28.35:1:0.375:2.8:1.325 (based on the total mass of the anode active material, with silicon accounting for 5% by mass). The mixture was stirred for 5 hours to obtain anode slurry. The anode slurry was uniformly coated onto anode current collector, dried, cold-pressed, and slit to obtain anode sheets. The specific capacity of the anode active material was 806.6 mAh / g, and the areal density of the anode active material layer was 0.116 g / 1540.25 mm². 2 .

[0187] 3. Preparation of electrolyte

[0188] In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate are mixed in a volume ratio of 1:1:1 to obtain an electrolyte solvent. Then, lithium salts LiPF6 and LiFSI are dissolved in the mixed solvent in a mass ratio of 9:1 to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0189] 4. Separating membrane

[0190] Polypropylene film is used as the separator.

[0191] 5. Preparation of secondary batteries

[0192] The above-mentioned positive electrode sheet, separator, and negative electrode sheet are wound or stacked in sequence to obtain a bare cell; the bare cell is placed in a packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a lithium-ion battery is obtained.

[0193] The preparation methods of lithium-ion batteries in Examples 2-19 and Comparative Examples 1-2 are the same as those in Example 1, except that the process parameters for battery preparation are different, as shown in Table 1.

[0194] In Examples 1-19, (positive electrode active material + lithium supplement) / (positive electrode active material + lithium supplement + conductive agent carbon black + binder) = 97%. In Example 12, the lithium supplement L... i2 The mass ratio of NiO2 to Li5FeO4 is 1:1.

[0195] Table 1

[0196] It is understood that the initial efficiency of the battery changes with the change in silicon content in Examples 2-5. The change in initial efficiency will affect the specific capacity of the positive electrode active material. Therefore, the specific capacity of the positive electrode active material in Examples 2-5 has changed accordingly.

[0197] The energy density and charging time of the batteries in Examples 1-19 and Comparative Examples 1-2 were characterized, and the characterization results are shown in Table 2.

[0198] 1. Energy density test:

[0199] 1) Measurement of discharge energy of a single battery cell, using the following method:

[0200] Let the individual battery cells stand at 25°C for 2 hours to ensure that the temperature of the individual battery cells is 25°C.

[0201] At 25°C, the battery cell is charged to the charging cutoff voltage at 0.1C, and then constant voltage charging is continued at the charging cutoff voltage until the current is 0.05C, at which point charging is cut off (where C represents the rated capacity of the battery cell).

[0202] Let the individual battery cells stand at 25°C for 1 hour;

[0203] At 25℃, the battery cells were discharged to the discharge cutoff voltage at 0.1C. The total discharge capacity C0 and the total discharge energy E0 of the battery cells were recorded.

[0204] 2) Battery cell weight measurement: Place the battery cell on the electronic balance until the weight stabilizes, and read the battery cell weight value M0;

[0205] 3) Energy density calculation: The energy density of a single battery cell is calculated as E0 / M0 (weight of the single battery cell).

[0206] 2. Charging time test:

[0207] Step 1: Voltage Calibration

[0208] 1) Place stacked three-electrode cells with the same battery design at 25°C for 30 minutes;

[0209] 2) After charging the battery cell to the charging cutoff voltage at 0.33C at 25℃, continue constant voltage charging at the charging cutoff voltage until the current is 0.05C and charging is cut off (where C represents the rated capacity of the battery cell).

[0210] 3) Let stand at 25℃ for 1 hour;

[0211] 4) Discharge each battery cell at 0.33C to the discharge cutoff voltage at 25℃, and record the total discharge capacity C1 of the battery cell;

[0212] 5) Let stand at 25℃ for 1 hour;

[0213] Step 2: Charging Test

[0214] 1) Let the stacked three-electrode battery cell stand at 25℃ for 30 minutes;

[0215] 2) 0.33C1 DC to discharge cutoff voltage;

[0216] 3) Let stand for 5 minutes;

[0217] 4) xC1 CC to charging cutoff voltage (three-electrode monitoring of anode potential; when the anode potential is 0V, proceed to the next step)

[0218] 5) Repeat steps 3) to 4) 9 times, with x taking the following values: 5, 4, 4.5, 3, 2, 1, 0.8, 0.5, 0.33.

[0219] 6) Take the value of x corresponding to the anode potential of 0V and the charging capacity Cx.

[0220] 7) Use Cx / C1 to obtain the corresponding SOCx, and the total charging time T = Σ(60 / x1×SOCx1), where x is the corresponding multiplier.

[0221] Table 2

[0222] Conclusion: As shown in Table 2, in Examples 1-19 of this application, controlling the nickel content in the positive electrode active material and using silicon-based materials in the negative electrode active material, while adding a lithium replenishing agent to the positive electrode active material layer, can simultaneously achieve a balance between battery energy density and fast charging performance. Comparative Example 1, which does not use silicon-based materials or a lithium replenishing agent, although achieving good fast charging performance, suffers from poor energy density and cannot achieve a balance between the two. This is because the negative electrode active material uses graphite, which has low capacity and low lithium-ion transport, resulting in a short charging time. Comparative Example 2, which does not use a lithium replenishing agent, while achieving good energy density, suffers from poor fast charging performance and also cannot achieve a balance between the two.

[0223] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery, wherein, The battery comprises: a positive electrode sheet comprising a positive electrode active material layer, the positive electrode active material layer comprising a positive electrode active material and a lithium supplement agent, a nickel content in 1 mol of the positive electrode active material being 0.8 mol-1 mol; a negative electrode sheet comprising a negative electrode active material layer, the negative electrode active material layer comprising a negative electrode active material, the negative electrode active material comprising a silicon-based material.

2. The battery of claim 1, wherein, The nickel content in 1 mol of the positive electrode active material is 0.88 mol-0.95 mol.

3. The battery according to claim 1 or 2, wherein A ratio of a capacity of the negative electrode sheet to a capacity of the positive electrode sheet is N / P, and N / P=1.02-1.

08.

4. The battery of any one of claims 1-3, wherein, The gram capacity of the positive electrode active material is 200 mAh / g-250 mAh / g.

5. The battery of any one of claims 1-4, wherein, Based on a total weight of the positive electrode active material layer, a mass percentage of the positive electrode active material is 96.5%-99.5%.

6. The battery of any one of claims 1-5, wherein, The areal density of the positive electrode active material layer is 0.347 g / 1540.25 mm 2 -0.547 g / 1540.25 mm 2 .

7. The battery of any one of claims 1-6, wherein, The positive electrode active material comprises a lithium-containing nickel transition metal oxide.

8. The battery of any one of claims 1-7, wherein, The chemical formula of the positive electrode active material includes: Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y , In the formula, x is 0.2-1.2, a is 0.8-1, b is 0-0.15, c is 0-0.15, d is 0-0.02, y is 0-0.1, M comprises at least one of Zr, Y, Al, Ti, W, Sr, Ta, Sb, Nb, Na, K, Ca or Ce, and A comprises at least one of N, F, S or Cl.

9. The battery of any one of claims 1-8, wherein, The volume average particle size Dv50 of the positive electrode active material is 3 μm-16 μm.

10. The battery of any one of claims 1-9, wherein, The positive electrode active material comprises first particles and second particles, the volume average particle size Dv50 of the first particles being 2 μm-25 μm, and the volume average particle size Dv50 of the second particles being 0.65 μm-10 μm.

11. The battery of any one of claims 1-10, wherein, The lithium supplement agent comprises at least one of Li5V2(PO4)3, LiVPO4F, LiNiO2, Li6CoO4, Co-Li2O, Co-Li2S, Li3N, Li2O, Li5FeO4, Li2O2, C2O4Li2, Li2OHCl, Li2CuO2, LiCoO2 or Li3ON.

12. The battery of any one of claims 1-11, wherein, The lithium supplement agent comprises at least one of LiNiO2, Li6CoO4, Co-Li2O, Li2O, Li5FeO4, Li2O2, C2O4Li2, Li2OHCl, Li2CuO2, LiCoO2 or Li3ON.

13. The battery of any one of claims 1-12, wherein, A mass ratio of the positive electrode active material to the lithium supplement agent is (19-99):

1.

14. The battery of any one of claims 1-13, wherein, The gram capacity of the negative electrode active material is 600 mAh / g-2200 mAh / g.

15. The battery of any one of claims 1-14, wherein, The silicon-based material comprises a silicon-carbon composite material, the silicon-carbon composite material comprising a three-dimensional network crosslinked pore structure, and silicon nanoparticles, at least a part of the silicon nanoparticles being arranged in the three-dimensional network crosslinked pore structure.

16. The battery of any one of claims 1-15, wherein, Based on a total mass of the negative electrode active material, a mass percentage of silicon elements is 5%-40%.

17. The battery of any one of claims 1-16, wherein, Based on a total mass of the negative electrode active material, a mass percentage of silicon elements is 10%-30%.

18. The battery of any one of claims 1-17, wherein, The areal density of the negative active material layer is 0.06 g / 1540.25 mm 2 -0.2 g / 1540.25 mm 2 .

19. The battery of any one of claims 1-18, wherein, Based on a total weight of the negative electrode active material layer, a mass percentage of the negative electrode active material is 92%-96.5%.

20. The battery of any one of claims 1-19, wherein, The battery further comprises an electrolyte, the electrolyte comprising lithium bisfluorosulfonylimide.

21. An electrical device, comprising: A battery comprising any of claims 1-20.

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