Electrolytes, batteries, and power-consuming devices

Abstract

The company provides an electrolyte, a battery and a power consumption device, wherein the electrolyte is A x O y Z- and PO2F2 - A includes at least one of P, S, or Si, and 1 ≤ x ≤ 2, 4 ≤ y ≤ 5, and 2 ≤ z ≤ 3.

Description

[Technical Field]

[0001] This application belongs to the field of secondary battery technology and specifically relates to electrolytes, batteries, and power consumption devices. [Background technology]

[0002] Lithium-ion batteries are not only used in energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, but are also widely used in electric transportation such as electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace.

[0003] With continuous charging and discharging cycles, the DC internal resistance (DCR) of conventional lithium-ion batteries continuously increases, thereby affecting the battery's power performance. [Overview of the project]

[0004] In light of the technical problems present in the background technology, this application aims to provide an electrolyte that reduces the DCR increase rate during the cycle charge-discharge process of a lithium-ion battery containing it, thereby improving the power performance of the lithium-ion battery.

[0005] To achieve the above objective, a first aspect of this application provides an electrolyte, the electrolyte being A x O y Z- and PO2F2 - A includes at least one of P, S, or Si, and 1 ≤ x ≤ 2, 4 ≤ y ≤ 5, and 2 ≤ z ≤ 3.

[0006] The electrolyte composition of this application can effectively reduce the DCR increase rate during the cycle charge-discharge process of a battery containing it, thereby improving the power performance of the lithium-ion battery.

[0007] In some embodiments of this application, A x O y Z- , PO4 3-, SO4 2- or Si2O5 2- and contains at least one of them, and selectively contains PO4 3- . This can reduce the increase rate of DCR in the cycle charge and discharge process of the lithium-ion battery containing it.

[0008] In some embodiments of the present application, based on the total mass of the electrolyte, the A x O y Z- and the total mass concentration of the PO2F2 - is 2000 ppm or less, and selectively 1500 ppm or less. This can reduce the increase rate of DCR in the cycle charge and discharge process of the lithium-ion battery containing it.

[0009] In some embodiments of the present application, based on the total mass of the electrolyte, the A x O y Z- has a mass concentration of m, the mass concentration of the PO2F2 - is n, and n / m = (10 - 1000):1, and selectively (100 - 500):1. This can reduce the increase rate of DCR in the cycle charge and discharge process of the lithium-ion battery containing it.

[0010] In some embodiments of the present application, based on the total mass of the electrolyte, the A x O y Z- has a mass concentration m of 1 ppm - 1000 ppm, and selectively 1 ppm - 200 ppm. This can reduce the increase rate of DCR in the cycle charge and discharge process of the lithium-ion battery containing it.

[0011] In some embodiments of the present application, based on the total mass of the electrolyte, the PO2F2 -The mass concentration n is 1 ppm to 1000 ppm, and selectively 1 ppm to 200 ppm. This can reduce the DCR increase rate during the cycle charge-discharge process of lithium-ion batteries containing it.

[0012] In some embodiments of this application, the electrolyte further comprises a film-forming additive. This can reduce the rate of increase in DCR during the cycle charge-discharge process of the lithium-ion battery containing it.

[0013] In some embodiments of this application, the mass concentration of the film-forming additive is w, with respect to the total mass of the electrolyte, and (m+n) / w is 1:(10-100), and selectively 1:(20-80). This makes it possible to reduce the rate of increase in DCR during the cycle charge-discharge process of a lithium-ion battery containing it.

[0014] In some embodiments of this application, the mass concentration w of the film-forming additive is 0.2%-0.5%, and selectively 0.25%-0.45%. This makes it possible to reduce the rate of increase in DCR during the cycle charge-discharge process of lithium-ion batteries containing it.

[0015] In some embodiments of this application, the film-forming additive comprises at least one of tris(trimethylsilyl) phosphate, tris(trimethylsilane) borate, and tris(trimethylsilane) phosphite. This reduces the rate of increase in DCR during the cycle charge-discharge process of a lithium-ion battery containing it.

[0016] A second aspect of this application provides a battery comprising the electrolyte described in the first aspect of this application, thereby providing a battery with excellent power performance.

[0017] In some embodiments of this application, the battery includes a positive electrode plate, and the positive electrode active material of the positive electrode plate is Volume-average particle size D of the positive electrode active material v50 is 1 μm-4 μm, and the condition is that it is selectively 1 μm-3 μm, The BET specific surface area of ​​the positive electrode active material is 1 m². 2 / g-4m 2 / g, selectively 1m 2 / g-3m 2 The condition is that it is / g, The compaction density of the positive electrode active material at a pressure of 300 MPa is 3.2 g / cm³. 3 -3.8g / cm 3 Therefore, selectively 3.3 g / cm³ 3 -3.6 g / cm³ 3 It satisfies at least one of the following conditions:

[0018] In some embodiments of this application, the battery includes a negative electrode plate, and the negative electrode active material of the negative electrode plate is Volume-average particle size D of the negative electrode active material v 50 is 1 μm-4 μm, and the condition is that it is selectively 1 μm-3 μm, The BET specific surface area of ​​the negative electrode active material is 1 m². 2 / g-4m 2 / g, selectively 1m 2 / g-3m 2 The condition is that it is / g, The compaction density of the negative electrode active material at a pressure of 300 MPa is 1.4 g / cm³. 3 -1.8g / cm 3 Therefore, selectively 1.5 g / cm³ 3 -1.7g / cm 3 It satisfies at least one of the following conditions:

[0019] A third aspect of this application provides a power consumption device including the battery described in the second aspect.

[0020] Additional aspects and advantages of this application are partially shown in the following description, partially revealed in the following description, or understood through the practice of this application. [Brief explanation of the drawing]

[0021] By reading the detailed description of the following optional embodiments, various other advantages and benefits will become apparent to those skilled in the art. The drawings are used solely to illustrate the purpose of the optional embodiments and are not to be considered limitations to this application. Note that in all drawings, the same drawing number indicates the same component. In the drawings, [Figure 1] This is a schematic diagram of the structure of a battery according to one embodiment of this application. [Figure 2] This is a schematic diagram of the structure of a battery module according to one embodiment of this application. [Figure 3] This is a schematic diagram of the structure of a battery pack according to one embodiment of this application. [Figure 4] Figure 3 is an exploded view. [Figure 5] This is a schematic diagram of one embodiment of a power-consuming device that uses a battery as a power source. [Modes for carrying out the invention]

[0022] The following describes in detail embodiments of the technical invention of this application. The following embodiments are merely examples to clarify the technical invention of this application and should not be used to limit the scope of protection of this application.

[0023] The “Examples” as used herein mean that certain features, structures, or characteristics described in conjunction with the Examples may be included in at least one Example of this Application. The appearance of this phrase at each location in the Specification does not necessarily refer to the same Example, nor do they represent mutually exclusive or alternative Examples. Those skilled in the art will understand, both explicitly and implicitly, that the Examples described herein can be combined with other Examples.

[0024] For simplicity and clarity, this specification specifically discloses only a range of certain numerical values. However, any lower limit and any upper limit may be combined to form an unspecified range, and any lower limit and any other lower limit may be combined to form an unspecified range, and similarly, any upper limit and any other upper limit may be combined to form an unspecified range. Furthermore, each point or single numerical value disclosed individually may itself act as a lower or upper limit when combined with any other point or single numerical value, or when combined with other lower or upper limits, to form an unspecified range.

[0025] In the description of the embodiments of this application, the term "and / or" merely describes a relationship between related objects, indicating that three relationships may exist. For example, A and / or B may represent three cases: A alone, a combination of A and B, or B alone. In this specification, the letter " / " generally indicates that the preceding and succeeding related objects are in an "or" relationship.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art relating to the present application. The terms used herein are solely for the purpose of describing specific embodiments and are not intended to limit this application. The terms “including” and “having” and any variations thereof in the description of the specification, claims, and drawings of this application are intentionally intended to cover the non-exclusive “including.”

[0027] Currently, market development trends indicate that the applications of lithium-ion batteries are becoming increasingly widespread. Lithium-ion batteries are not only used in energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, but also in electric transportation systems such as electric bicycles, electric motorcycles, and electric vehicles, as well as in various fields including military equipment and aerospace. With the continuous expansion of lithium-ion battery applications, the market demand is also constantly growing.

[0028] During the charging and discharging process of a lithium-ion battery, lithium ions desorb from the positive electrode plate, move to the negative electrode plate via the electrolyte under the influence of an electric field, and are absorbed into the negative electrode active material. When the battery discharges, lithium ions desorb from the negative electrode active material, move to the positive electrode plate via the electrolyte under the influence of an electric field, and are absorbed into the positive electrode active material. As the secondary battery undergoes a charge-discharge cycle, side reactions occur between the positive electrode plate and the electrolyte. On the one hand, these side reactions consume active lithium as it is involved in the reaction. On the other hand, the accumulation of side reaction products on the surface of the positive electrode active material makes it difficult to transport lithium ions, preventing complete absorption of lithium ions into the material. This ultimately leads to a continuous loss of active lithium in the positive electrode active material, causing a continuous increase in the DCR of the lithium-ion battery and thereby reducing the battery's power performance.

[0029] In this application, the electrolyte is A x O y Z- and PO2F2 - A includes at least one of P, S, or Si, and 1≦x≦2, 4≦y≦5, 2≦z≦3, and on the other hand, A x O y Z- and PO2F2 - It can provide AO bonds, A=O bonds, PO bonds and P=O bonds, and these AO bonds, A=O bonds, PO bonds and P=O bonds can bond with lithium ions on the surface of the positive electrode plate, thereby stabilizing the active lithium on the positive electrode plate, while A x O y Z- Because the binding force of the middle ligand A to O is insufficient, it easily loses electrons at high voltage, and after oxidation, it can form a film on the surface of the positive electrode plate, thereby protecting the active lithium on the positive electrode plate. At the same time, during the battery charging process, PO2F2 - The P=O bond above is easily oxidized by the positive electrode active material after lithium desorption on the positive electrode plate, and after the P=O is oxidized, the remaining F ions readily bond with lithium ions, thereby A x O y Z-This improves the problem of low ionic conductivity of surface products after oxidation, and because the radii of both F ions and lithium ions are close, the binding energy is very high, allowing them to well cover the surface of the positive electrode material, thereby reducing the loss of active lithium. As a result, adopting the electrolyte composition of this application can effectively reduce the loss of active lithium, lower the DCR increase rate during the cycle charge-discharge process of batteries containing it, and improve the power performance of the battery.

[0030] The electrolytes disclosed in the embodiments of this application are applied to lithium-ion batteries, and the batteries disclosed in the embodiments of this application can be used in power-consuming devices that use batteries as a power source or in various energy storage systems that use batteries as energy storage elements. Power-consuming devices may include, but are not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, and spacecraft. Here, electric toys may include stationary or mobile electric toys, such as game consoles, electric vehicle toys, electric steamship toys and electric airplane toys, and spacecraft may include airplanes, rockets, spacecraft and spaceships.

[0031] A first aspect of this application provides an electrolyte, the electrolyte being A x O y Z- and PO2F2 - A includes at least one of P, S, and Si, and 1 ≤ x ≤ 2, 4 ≤ y ≤ 5, and 2 ≤ z ≤ 3.

[0032] This application includes at least the beneficial effects described below: The electrolyte of this application is A x O y Z- and PO2F2 - It includes, on the other hand, A x O y Z- and PO2F2 -It can provide AO bonds, A=O bonds, PO bonds and P=O bonds, and these AO bonds, A=O bonds, PO bonds and P=O bonds can bond with lithium ions on the surface of the positive electrode plate, thereby stabilizing the active lithium on the positive electrode plate, while A x O y Z- Because the binding force of the central ligand A to O is insufficient, electrons are easily lost at high voltages, and after oxidation, a film can be formed on the surface of the positive electrode plate, thereby protecting the active lithium on the positive electrode plate. At the same time, during the battery charging process, the P=O bond on PO2F2- is easily oxidized by the positive electrode active material after lithium desorption on the positive electrode plate. After P=O is oxidized, the remaining F ions readily bond with lithium ions, thereby improving the problem of low ionic conductivity of surface products after AxOyZ- is oxidized. Furthermore, because the radii of both F ions and lithium ions are close, the bonding energy is very high, allowing them to well cover the surface of the positive electrode material, thereby reducing the loss of active lithium. Thus, by adopting the electrolyte composition of this application, the loss of active lithium can be effectively reduced, the DCR increase rate during the cycle charge-discharge process of batteries containing it can be reduced, and the power performance of the battery can be improved.

[0033] In some embodiments of this application, A x O y Z- In this equation, A may include at least one of P, S, or Si, such that 1 ≤ x ≤ 2, 4 ≤ y ≤ 5, and 2 ≤ z ≤ 3, for example, x is 1 or 2, y is 4 or 5, and z is 2 or 3. As an example, A x O y Z- , PO4 3- SO4 2- or Si2O5 2- It may include at least one of the above. This results in the above composition A x O y Z-The A-O bond and A=O bond provided thereby can bind to lithium ions on the surface of the positive electrode plate, thereby stabilizing the active lithium in the positive electrode plate, and at the same time A x O y Z- Since the binding force of A to O of the central ligand of A is insufficient, it is easy to form a film on the surface of the positive electrode plate after electrons are lost and oxidized, thereby protecting the active lithium in the positive electrode plate. In some other embodiments of the present application, A x O y Z- may include PO4 3-

[0034] It should be noted that in the present application, A x O y Z- and PO2F2 - are added to the electrolyte in the form of lithium salts, such as Li3PO4, Li2SO4, Li2Si2O5, LiPO2F2.

[0035] In some embodiments of the present application, based on the total mass of the electrolyte, the sum of the mass concentrations of the A x O y Z- and the PO2F2 - is 2000 ppm or less, for example, 2 ppm - 2000 ppm, 10 ppm - 2000 ppm, 50 ppm - 2000 ppm, 100 ppm - 2000 ppm, 200 ppm - 2000 ppm, 300 ppm - 2000 ppm, 400 ppm - 2000 ppm, 500 ppm - 2000 ppm, 600 ppm - 2000 ppm, 700 ppm - 2000 ppm, 800 ppm - 2000 ppm, 900 ppm - 2000 ppm, 1000 ppm - 2000 ppm, 1100 ppm - 1900 ppm, 1200 ppm - 1800 ppm, 1300 ppm - 1700 ppm, 1400 ppm - 1600 ppm, 1400 ppm - 1500 ppm, etc. Thereby, the present application controls the A x O y Z- and PO2F2 - ​Controlling the total mass concentration of A within the above range can not only improve the battery cycle life but also reduce the DCR increase rate during the cycle charge-discharge process of the lithium-ion battery, thereby improving the power performance of the lithium-ion battery. In some other embodiments of this application, the total mass of the electrolyte is used as a reference to A x O y Z- and the PO2F2 - The total mass concentration is 1500 ppm or less.

[0036] It should be explained that "ppm" refers to mass concentration, which is the amount of A in the electrolyte. x O y Z- and PO2F2 - This refers to the ratio of the total mass of A to the mass of the electrolyte, where 1 ppm = 0.0001%. At the same time, A in the electrolyte in this application x O y Z- and PO2F2 - The mass concentration of can be tested using instruments and methods known in this art, for example, by ion chromatography, using an ICS-900 ion chromatograph as the instrument, and the test method specifically refers to GB / T36240-2018.

[0037] In some embodiments of this application, the total mass of the electrolyte is used as the basis for A x O y Z- The mass concentration of is m, and the PO2F2 - The mass concentration of is n, where n / m = (10-1000):1, for example (20-980):1, (30-950):1, (40-920):1, (50-900):1, (80-880):1, (100-850):1, (120-820):1, (150-800):1, (180-780):1, (200-750):1, (250-700):1, (300-650):1, (350-600):1, (400-550):1, (450-500):1, (480-500):1, etc. Thus, this application relates to the PO2F2 in the electrolyte.- The mass concentration n and the aforementioned A x O y Z- Controlling the ratio n / m of the mass concentration m to within the above range reduces gas generation and the DCR increase rate during the cycle charge-discharge process of the lithium-ion battery, thereby improving the power performance and cycle performance of the lithium-ion battery. In some other embodiments of this application, the total mass of the electrolyte is used as the reference, x O y Z- The mass concentration m and the PO2F2 - The mass concentration n satisfies the condition n / m = (100-500):1.

[0038] In some embodiments of this application, the total mass of the electrolyte is used as the basis for A x O y Z- The mass concentration m ranges from 1 ppm to 1000 ppm, for example, 2 ppm to 1000 ppm, 5 ppm to 1000 ppm, 10 ppm to 1000 ppm, 50 ppm to 1000 ppm, 80 ppm to 1000 ppm, 100 ppm to 1000 ppm, 120 ppm to 1000 ppm, 150 ppm to 1000 ppm, 170 ppm to 1000 ppm, 200 ppm to 1000 ppm, 300 ppm to 1000 ppm, 400 ppm to 1000 ppm, 500 ppm to 1000 ppm, 600 ppm to 1000 ppm, 700 ppm to 1000 ppm, 800 ppm to 1000 ppm, and 900 ppm to 1000 ppm. Therefore, this application relates to the A in the electrolyte. x O y Z- Controlling the mass concentration of within the above range reduces the generation of degradation gases and lowers the DCR increase rate during the cycle charge-discharge process of the lithium-ion battery, thereby improving the power performance and cycle performance of the lithium-ion battery. In some other embodiments of this application, the total mass of the electrolyte is used as the reference to A x O y Z- The mass concentration m ranges from 1 ppm to 200 ppm.

[0039] In some embodiments of this application, the total mass of the electrolyte is used as the basis for the PO2F2 - The mass concentration n ranges from 1 ppm to 1000 ppm, for example, 2 ppm to 1000 ppm, 5 ppm to 1000 ppm, 10 ppm to 1000 ppm, 50 ppm to 1000 ppm, 80 ppm to 1000 ppm, 100 ppm to 1000 ppm, 120 ppm to 1000 ppm, 150 ppm to 1000 ppm, 170 ppm to 1000 ppm, 200 ppm to 1000 ppm, 300 ppm to 1000 ppm, 400 ppm to 1000 ppm, 500 ppm to 1000 ppm, 600 ppm to 1000 ppm, 700 ppm to 1000 ppm, 800 ppm to 1000 ppm, and 900 ppm to 1000 ppm. Therefore, this application relates to the PO2F2 in the electrolyte. - Controlling the mass concentration of within the above range can reduce the DCR increase rate during the cycle charge-discharge process of the lithium-ion battery and improve the power performance of the lithium-ion battery. In some other embodiments of this application, the PO2F2 is used with respect to the total mass of the electrolyte. - The mass concentration n is between 1 ppm and 200 ppm.

[0040] In some embodiments of this application, the electrolyte may further contain a film-forming additive. Specifically, the “film-forming additive” may be understood as a substance added to the electrolyte that can promote the formation of a CEI film (positive electrode electrolyte interface) on the surface of the positive electrode plate and / or a SEI film (solid electrolyte interface film) on the surface of the negative electrode plate. This application describes adding a film-forming additive to the electrolyte, which is A x O y Z- and PO2F2 - By working in conjunction with this, film formation on the surface of the positive electrode plate can be promoted, effectively reducing the loss of active lithium, thereby lowering the DCR increase rate during the cycle charge-discharge process of the battery containing it, and improving the power performance of the battery.

[0041] In some embodiments of this application, the mass concentration of the film-forming additive is w, relative to the total mass of the electrolyte, and (m+n) / w is 1:(10-100), for example 1:(15-95), 1:(20-90), 1:(25-85), 1:(30-80), 1:(35-75), 1:(40-70), 1:(45-65), 1:(50-60), 1:(55-60), etc. Thus, this application relates to the A in the electrolyte. x O y Z- and the aforementioned PO2F2 - Controlling the mass concentration of and the ratio of the mass concentration to the film-forming additive within the above range can reduce the DCR increase rate during the cycle charge-discharge process of the lithium-ion battery and improve the power performance of the lithium-ion battery. In some other embodiments of this application, A x O y Z- The mass concentration m of the PO2F2 - The mass concentration n of the substance and the mass concentration w of the film-forming additive satisfy the condition that (m+n) / w = 1:(20-80).

[0042] In some embodiments of this application, the mass concentration w of the film-forming additive is 0.2%-0.5%, for example, 0.22%-0.48%, 0.25%-0.45%, 0.27%-0.42%, 0.3%-0.4%, 0.32%-0.38%, 0.35%-0.37%, etc. Thus, this application demonstrates that controlling the mass concentration w of the film-forming additive in the electrolyte to the above range can reduce the DCR increase rate during the cycle charge-discharge process of the lithium-ion battery and improve the power performance of the lithium-ion battery. In some other embodiments of this application, the mass concentration w of the film-forming additive is 0.25%-0.45%.

[0043] It should be noted that the test method for determining the concentration of the film-forming additive in the electrolyte in this application can be performed using instruments and methods known in the art, such as organic gas chromatography.

[0044] For example, the film-forming additive may contain at least one of tris(trimethylsilyl) phosphate, tris(trimethylsilane) borate, or tris(trimethylsilane) phosphite.

[0045] The electrolyte may further contain an electrolyte salt and a solvent.

[0046] For example, the electrolyte salt may contain at least one of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0047] For example, the solvent may include at least one of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), or diethyl sulfone (ESE).

[0048] In some embodiments, the electrolyte may further include additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, additives that improve the battery's high-temperature performance, and additives that improve the battery's low-temperature performance.

[0049] A second aspect of this application provides a battery comprising the electrolyte described in the first aspect of this application, thereby having low DC internal resistance and excellent power performance.

[0050] A battery is a device that can be continuously used by activating its active material through a charging process after discharge.

[0051] Generally, a battery consists of a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. During charging and discharging of the battery, active ions intermittently

[0052] In some embodiments of this application, the battery may be a lithium-ion battery.

[0053] [Positive electrode plate] In a battery, the positive electrode plate generally includes a positive electrode current collector and a positive electrode active material layer placed on the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.

[0054] The positive electrode current collector may be a conventional metal foil sheet or a composite current collector (a composite current collector may be formed by placing a metal material on a polymer substrate). For example, the positive electrode current collector may be made of aluminum foil.

[0055] The specific type of positive electrode active material is not limited, and any active material known in the art that can be used in the positive electrode of a secondary battery may be used, and a person skilled in the art can select it according to their actual needs.

[0056] For example, the positive electrode active material may include, but is not limited to, at least one of lithium transition metal oxides, lithium-containing phosphates with an olivine structure, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Examples of lithium-containing phosphates with an olivine structure may include, but is not limited to, at least one of lithium iron phosphate, composite materials of lithium iron phosphate and carbon, lithium manganese phosphate, composite materials of lithium manganese phosphate and carbon, lithium iron manganese phosphate, lithium iron manganese phosphate and carbon, and their modified compounds. All of these materials are commercially available.

[0057] In some embodiments of this application, the volume-average particle size D of the positive electrode active material v 50 is 1 μm-4 μm, for example, the volume-average particle size D of the positive electrode active material. v 50 may be 1 μm-3 μm, 2 μm-3 μm, etc. In some other embodiments of this application, the volume average particle size D of the positive electrode active material v 50 corresponds to a size of 1 μm to 3 μm.

[0058] In this application, the volume-average particle size D v 50 refers to the particle size corresponding to the point when the cumulative volume distribution percentage reaches 50%, and is measured using a laser particle size analyzer (e.g., Malvern Master Size 3000), referring to, for example, the standard GB / T 19077-2016.

[0059] In some embodiments of this application, the BET specific surface area of ​​the positive electrode active material is 1 m². 2 / g-4m 2 The value is / g, and for example, the specific surface area of ​​the positive electrode active material is 1.5m². 2 / g-3.5m 2 / g, 2m 2 / g-3m 2 / g, 2.5m 2 / g-3m 2 / g, 2.8m 2 / g-3m 2 It may also be / g, etc. In some other embodiments of this application, the BET specific surface area of ​​the positive electrode active material is 1m 2 / g-3m 2 It is / g.

[0060] In this application, the specific surface area of ​​the positive electrode active material can be obtained by testing with reference to the following method: Using a Micromeritics GeminiVII2390 multi-station fully automated specific surface area and pore size analyzer, approximately 7 g of sample is taken and placed in a 9 cc long tube with bubbles, degassed at 200°C for 2 hours, and then tested in the main unit to obtain the BET (specific surface area) data of the positive electrode active material.

[0061] In some embodiments of this application, the compaction density of the positive electrode active material at a pressure of 300 MPa is 3.2 g / cm³. 3 -3.8g / cm 3 For example, the compaction density of the positive electrode active material at a pressure of 300 MPa is 3.2 g / cm³. 3 -3.7g / cm 3 3.3 g / cm³ 3 -3.6 g / cm³ 3 3.4 g / cm³ 3 -3.5g / cm 3 The following may also be used. In some embodiments of this application, the compaction density of the positive electrode active material at a pressure of 300 MPa is 3.3 g / cm³. 3 -3.6 g / cm³ 3 That is the case.

[0062] In this application, "consolidation density" has the meaning known in the art and can be measured using instruments and methods known in the art. For example, the following test method can be used: A fixed amount m of powder is placed in a mold specifically for consolidation, the mold is placed in a consolidation density instrument, a pressure of 300 MPa is set, the instrument measures the volume v of the powder under a pressure of 300 MPa, and the consolidation density is calculated using the formula density = mass m / volume v (see GB / T24533-2009 for specifics).

[0063] Specifically, the volume-average particle size D of the positive electrode active material of this application. v 50. When at least one of the specific surface area and the compaction density at a pressure of 300 MPa is within the above range, the conduction distance within the positive electrode active material is small, surface side reactions are few, promoting the positive electrode active material to exert its gram capacity and improving the capacity retention rate of the battery containing it.

[0064] [Negative electrode plate] In a battery, the negative electrode plate generally includes a negative electrode current collector and a negative electrode active material layer placed on the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

[0065] The negative electrode current collector may be a conventional metal foil sheet or a composite current collector (for example, a composite current collector may be formed by placing a metal material on a polymer substrate). For example, the negative electrode current collector may be made of copper foil.

[0066] The specific type of negative electrode active material is not limited, and any active material known in the art that can be used in secondary battery negative electrodes may be used, and those skilled in the art can select according to their actual needs. For example, the negative electrode active material may include, but is not limited to, artificial graphite, natural graphite, hard carbon, soft carbon, silicone-based materials, and tin-based materials. The silicone-based material may include at least one of elemental silicone, silicone oxide (e.g., silicon dioxide), silicone-carbon composite, silicone-nitrogen composite, and silicone alloy. The tin-based material may include at least one of elemental tin, tin acid compounds, and tin alloys. All of these materials are commercially available.

[0067] In some embodiments, the negative electrode active material may include a silicon-based material in order to further improve the energy density of the battery.

[0068] In some embodiments of this application, the volume-average particle size D of the negative electrode active material v 50 is 1 μm-4 μm, for example, the volume-average particle size D of the negative electrode active material. v 50 may be 1 μm-3 μm, 2 μm-3 μm, etc. In some other embodiments of this application, the volume average particle size D of the negative electrode active material v 50 corresponds to a size of 1 μm to 3 μm.

[0069] In this application, the volume-average particle size D of the negative electrode active material v The meaning and test method of 50 is the volume-average particle size D of the positive electrode active material. v You can refer to the meaning and testing methods for item 50.

[0070] In some embodiments of this application, the BET specific surface area of ​​the negative electrode active material is 1 m². 2 / g-4m 2 The value is / g, and for example, the specific surface area of ​​the negative electrode active material is 1.5m². 2 / g-3.5m 2 / g, 2m 2 / g-3m 2 / g, 2.5m 2 / g-3m2 / g, 2.8m 2 / g-3m 2 It may also be / g, etc. In some other embodiments of this application, the BET specific surface area of ​​the negative electrode active material is 1m 2 / g-3m 2 It is / g.

[0071] In this application, the method for testing the BET specific surface area of ​​the negative electrode active material may refer to the method for testing the BET specific surface area of ​​the positive electrode active material.

[0072] In some embodiments of this application, the compaction density of the negative electrode plate is 1.4 g / cm³. 3 -1.8g / cm 3 For example, 1.4 g / cm³ 3 -1.7g / cm 3 1.5 g / cm³ 3 -1.7g / cm 3 1.6 g / cm³ 3 -1.7g / cm 3 And so on. In some other embodiments of this application, the compaction density of the negative electrode plate is 1.5 g / cm³. 3 -1.7g / cm 3 This allows for improved cycle performance of batteries containing it.

[0073] In this application, "consolidation density of the negative electrode plate" has a meaning known in the art and can be measured using instruments and methods known in the art. For example, the test method can refer to the test method for "consolidation density of the positive electrode plate" described above. It should be noted that the negative electrode is generally wiped of the active material layer with deionized water.

[0074] The negative electrode active material layer generally further selectively includes an adhesive, a conductive agent, and other selective additives.

[0075] For example, the conductive agent may include at least one of the following: superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0076] For example, the adhesive may contain at least one of the following: styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0077] For example, other selective additives may include thickeners and dispersants (e.g., sodium carboxymethylcellulose CMC-Na), and PTC thermistor materials.

[0078] As the separator described above, this application does not particularly limit it, and any known porous structure separator having electrochemical and mechanical stability can be selected and used according to actual needs, for example, it may include a single-layer or multi-layer film containing at least one of glass fibers, nonwoven fabrics, polyethylene, polypropylene, and polyvinylidene fluoride.

[0079] The embodiments of this application are not particularly limited to the shape of the battery, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows a rectangular secondary battery 1 as an example.

[0080] In some embodiments, the battery may include an casing used to package a positive electrode plate, a negative electrode plate, and an electrolyte.

[0081] In some embodiments, the exterior may include a case and a cover plate. Here, the case may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing and forming a housing cavity. The case has an opening that communicates with the housing cavity, and the cover plate can cover the opening so as to seal the housing cavity.

[0082] The positive electrode plate, negative electrode plate, and separator can be formed into an electrode assembly by a winding or lamination process. The electrode assembly is packaged in the housing cavity. The number of electrode assemblies included in the battery may be one or more and can be adjusted according to the requirements.

[0083] In some embodiments, the battery casing may include a rigid case, such as a rigid plastic case, an aluminum case, or a steel case.

[0084] The battery casing may include a pouch, such as a bag-shaped pouch. The material of the pouch may include at least one of the following plastics: polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0085] In some embodiments, the batteries can be assembled into a battery module, and the number of batteries included in the battery module may be multiple, with the specific number being adjustable depending on the application and capacity of the battery module.

[0086] Figure 2 shows an example of a battery module 2. Referring to Figure 2, multiple secondary batteries 1 may be installed in sequence along the longitudinal direction of the battery module 2. Of course, they may be arranged in any other manner. Furthermore, these multiple secondary batteries 1 may be fixed in place by fasteners.

[0087] The battery module 2 may further include a housing having a housing space, in which a plurality of secondary batteries 1 are housed. In some embodiments, the battery modules may further be assembled into a battery pack, the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0088] Figures 3 and 4 show an example of a battery pack 3. Referring to Figures 3 and 4, the battery pack 3 may include a battery box and a plurality of battery modules 2 installed in the battery box. The battery box includes an upper housing 4 and a lower housing 5, the upper housing 4 being lidable on the lower housing 5 and forming a sealed space for housing the battery modules 2. The plurality of battery modules 2 may be arranged in the battery box in any manner.

[0089] A third aspect of this application provides a power-consuming device including a battery as described in the second aspect. Specifically, the battery may serve as a power source for the power-consuming device or as an energy storage unit for the power-consuming device. The power-consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptop computers), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships and satellites, and energy storage systems.

[0090] Figure 5 shows an example of a power-consuming device. This power-consuming device includes pure electric vehicles, hybrid electric vehicles, or plug-in hybrid electric vehicles.

[0091] Other examples of power-consuming devices may include mobile phones, tablet computers, and laptop computers. These power-consuming devices generally require a thin design and may use batteries as their power source.

[0092] To clarify the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application, the embodiments are described in more detail below, linked to the drawings. Clearly, the embodiments described are only some, and not all, embodiments of this application. The following description of at least one exemplary embodiment is for illustrative purposes only and does not imply any limitation on this application or its applications. All other embodiments derived from the embodiments of this application without the creative effort of a person skilled in the art are all within the scope of protection of this application.

[0093] Example 1 1. Manufacturing of positive electrode plates Cathode active material LiNi 0.7 Co 0.1 Mn 0.1 O2, conductive agent Super P, and adhesive polyvinylidene fluoride (PVDF) were prepared as a positive electrode slurry in N-methylpyrrolidone (NMP), where the solid content of the positive electrode slurry was 50 wt%, and LiNi 0.7 Co 0.1 Mn 0.1 The mass ratio of O2, Super P, and PVDF was 8:1:1. The positive electrode slurry was applied to the upper and lower surfaces of the current collector aluminum foil and dried at 85°C. After cold pressing, the material was trimmed, cut, and slit, and then dried for 4 hours under vacuum conditions at 85°C to produce the positive electrode plate.

[0094] 2. Manufacturing of the negative electrode plate A negative electrode slurry was prepared by uniformly mixing graphite, the conductive agent Super P, the thickening agent carboxymethylcellulose (CMC), and the adhesive styrene-butadiene rubber (SBR) with deionized water. The solid content of the negative electrode slurry was 30 wt%, and the mass ratio of graphite, silicon dioxide, Super P, CMC, and adhesive styrene-butadiene rubber (SBR) in the solid components was 88:7:3:2. The negative electrode slurry was applied to the upper and lower surfaces of the copper foil current collector and dried at 85°C. Then, after cold pressing, trimming, cutting, and slitting, the negative electrode plate was dried for 12 hours under vacuum conditions at 120°C.

[0095] 3. Manufacturing of electrolyte In a glove box filled with argon gas (water content <10 ppm, oxygen gas content <1 ppm), Li z A x O yAnd LiPO2F2 was added to an organic solvent (the organic solvent contained ethylene carbonate (EC) and ethyl methyl carbonate (EMC), with a mass ratio of EC to EMC of 3:7), and after homogeneous mixing, LiPF6 and LiFSI were slowly added, and after the lithium salt was completely dissolved, an electrolyte with a lithium salt concentration of 1 mol / L was obtained.

[0096] 4. Separator A 16 μm polyethylene film was used as the separator.

[0097] 5. Manufacturing of lithium-ion batteries The positive electrode plate, separator, and negative electrode plate are stacked in order, with the separator positioned between the positive and negative electrode plates to isolate them. The stack is then wound up to obtain a bare cell, tabs are welded on, the bare cell is placed in an outer casing, the manufactured electrolyte is injected into the dried battery core, and packaging, setting, chemical formation, shaping, and capacity testing are performed to complete the manufacturing of a lithium-ion battery (pouch lithium-ion battery, thickness 4.0 mm, width 60 mm, length 140 mm).

[0098] The manufacturing methods for lithium-ion batteries in Examples 2-39 and Comparative Examples 1-4 are the same as in Example 1, the only difference being the composition of additives in the electrolyte, as specifically shown in Table 1.

[0099] [Table 1-1]

[0100] [Table 1-2]

[0101] [Table 1-3]

[0102] The DCR increase rates of the lithium-ion batteries obtained in Examples 1-39 and Comparative Examples 1-4 are characterized, and the characterization results are shown in Table 2.

[0103] Test method for determining the DCR increase rate of lithium-ion batteries The battery's state of charge (SOC) was adjusted to 50% before the cycle began. It was then discharged at 4C for 30 seconds, with the voltage before discharge noted as V1 and the voltage after discharge noted as V2. DCR1 = (V1 - V2) / I (where I corresponds to the current value of the 4C discharge) was calculated, and the battery was removed after 300 cycles. DCR2 was tested using a similar method, and ΔDCR = (DCR2 - DCR1) / DCR1 was calculated, where ΔDCR is the rate of increase in the battery's DCR.

[0104] [Table 2-1]

[0105] [Table 2-2]

[0106] As can be seen from Table 2, the DCR increase rate of the lithium-ion batteries in Examples 1-39 is significantly lower than that of Comparative Examples 1-4, and therefore A in this application x O y Z- and PO2F2 - This study demonstrates that an electrolyte containing [specific substance] can effectively reduce the DCR increase rate during the cycle charge-discharge process of a battery containing it, thereby improving the power performance of the lithium-ion battery.

[0107] Finally, it should be noted that the above embodiments are merely for illustrative purposes and not limiting purposes. While the application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications can still be made to the embodiments described above, or equivalent substitutions can be made to some or all of the technical features thereof. Such modifications or substitutions should not cause the essence of the corresponding invention to deviate from the scope of the invention in each embodiment of this application, and should all be included within the scope of the claims and specification of this application. In particular, unless there is a structural conflict, the technical features referred to in each embodiment may be combined in any manner. This application is not limited to any specific embodiment disclosed in the specification, but includes all inventions that fall within the scope of the claims. [Explanation of symbols]

[0108] 1: Rechargeable battery, 2: Battery module, 3: Battery pack, 4: Upper casing, 5: Lower casing.

Claims

1. A ｘ O ｙ Ｚ－ and PO ２ F ２ － An electrolyte containing A, where A contains at least one of P, S, or Si, and 1 ≤ x ≤ 2, 4 ≤ y ≤ 5, and 2 ≤ z ≤ 3.

2. The above-mentioned A ｘ O ｙ Ｚ－ is at least one of PO ４ ３－ , SO ４ ２－ or Si ２ O ５ ２－ The electrolytic solution according to claim 1, which contains at least one of them.

3. A ｘ O ｙ Ｚ－ , PO ４ ３－ The electrolyte according to claim 1 or 2, comprising:

4. Based on the total mass of the electrolyte, A ｘ O ｙ Ｚ－ and the PO ２ F ２ － The electrolyte according to any one of claims 1 to 3, wherein the total mass concentration of is 2000 ppm or less.

5. Based on the total mass of the electrolyte, A ｘ O ｙ Ｚ－ and the PO ２ F ２ － The electrolyte according to any one of claims 1 to 4, wherein the total mass concentration of is 1500 ppm or less.

6. Based on the total mass of the electrolyte, A ｘ O ｙ Ｚ－ The mass concentration of is m, and the PO ２ F ２ － The electrolyte according to any one of claims 1 to 5, wherein the mass concentration of is n and n / m = (10 - 1000):

1.

7. The electrolyte according to claim 6, wherein n / m = (100 - 500):

1.

8. Based on the total mass of the electrolyte, A ｘ O ｙ Ｚ－ The electrolyte according to claim 6 or 7, wherein the mass concentration m is 1 ppm to 1000 ppm.

9. Based on the total mass of the electrolyte, A ｘ O ｙ Ｚ－ The electrolyte according to any one of claims 6 to 8, wherein the mass concentration m is 1 ppm to 200 ppm.

10. Based on the total mass of the electrolyte, the PO ２ F ２ － The electrolyte according to any one of claims 6 to 9, wherein the mass concentration n is 1 ppm to 1000 ppm.

11. Based on the total mass of the electrolyte, the PO ２ F ２ － The electrolyte according to any one of claims 6 to 10, wherein the mass concentration n is 1 ppm to 200 ppm.

12. The electrolyte according to any one of claims 6 to 11, further comprising a film-forming additive.

13. The electrolyte according to claim 12, wherein the mass concentration of the film-forming additive is w, with respect to the total mass of the electrolyte, and (m + n) / w is 1:(10 - 100).

14. The electrolyte according to claim 13, wherein (m+n) / w is 1:(20-80).

15. The electrolyte according to claim 13 or 14, wherein the mass concentration w of the film-forming additive is 0.2% to 0.5%.

16. The electrolyte according to any one of claims 13 to 15, wherein the mass concentration w of the film-forming additive is 0.25% to 0.45%.

17. The electrolyte according to any one of claims 12 to 16, wherein the film-forming additive comprises at least one of tris(trimethylsilyl) phosphate, tris(trimethylsilane) borate, or tris(trimethylsilane) phosphite.

18. A battery comprising the electrolyte according to any one of claims 1 to 17.

19. The battery according to claim 18, wherein the battery includes a lithium-ion battery.

20. The battery includes a positive electrode plate, and the positive electrode active material of the positive electrode plate is Volume-average particle size D of the positive electrode active material ｖ 50 is a condition that is 1 μm - 4 μm, The BET specific surface area of ​​the positive electrode active material is 1 m² ２ / g-4m ２ The condition is that / g, The compaction density of the positive electrode active material at a pressure of 300 MPa is 3.2 g / cm³. ３ -3.8 g / cm ３ The battery according to claim 18 or 19, which satisfies at least one of the following conditions:

21. The battery includes a negative electrode plate, and the negative electrode active material of the negative electrode plate is Volume-average particle size D of the negative electrode active material ｖ 50 is a condition that is 1 μm - 4 μm, The BET specific surface area of ​​the negative electrode active material is 1 m² ２ / g-4m ２ The condition is that / g, The compaction density of the negative electrode active material at a pressure of 300 MPa is 1.4 g / cm³. ３ -1.8 g / cm ３ A battery according to any one of claims 18 to 20, which satisfies at least one of the following conditions:

22. A power-consuming device comprising a battery according to any one of claims 18 to 21.

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