Electrolyte, battery and electrical device

Abstract

An electrolyte comprising: A x O y Z- and PO2F2 - , where A includes at least one of P, S or Si, 1≤x≤2, 4≤y≤5 and 2≤z≤3.

Description

TECHNICAL AREA

[0001] This application concerns the field of secondary battery technology and relates in particular to an electrolyte, a battery and an electrical device. BACKGROUND

[0002] Lithium-ion batteries are not only used in energy storage systems such as hydroelectric power plants, thermal power plants, wind turbines and solar power plants, but are also used in many other areas, e.g. in electric means of transport such as electric bicycles, electric motorcycles and electric vehicles, in military equipment and in aerospace.

[0003] During continuous charging and discharging cycles, the direct current resistance (DCR) of existing lithium-ion batteries increases continuously, which affects the performance of the batteries. SUMMARY

[0004] Given the underlying technical problems, this application provides an electrolyte whose aim is to reduce the DCR growth rate of a lithium-ion battery, including the electrolyte, during charge and discharge cycles, thereby improving the performance of the lithium-ion battery.

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

[0006] The electrolyte formulated according to this application can effectively reduce the DCR growth rate of a battery containing the electrolyte during charge and discharge cycles, thereby improving the performance of the lithium-ion battery.

[0007] In some embodiments of this application, A contains x O y Z- at least one of the substances PO4 3- , SO4 2- or Si2O5 2- , possibly including PO4 3- This can reduce the DCR growth rate of the lithium-ion battery, including the electrolyte, during charge and discharge cycles.

[0008] In some embodiments of this application, the total mass concentration of A is x O y Z- and PO2F2 - , based on the total mass of the electrolyte, less than or equal to 2000 ppm, optionally less than or equal to 1500 ppm. This can reduce the DCR growth rate of the lithium-ion battery, including the electrolyte, during charge and discharge cycles.

[0009] In some embodiments of this application, based on the total mass of the electrolyte, the mass concentration of A is x O yZ- m, the mass concentration of PO2F2 - n and n / m=(10-1000):1, optionally (100-500):1. This can reduce the DCR growth rate of the lithium-ion battery, including the electrolyte, during charge and discharge cycles.

[0010] In some embodiments of this application, the mass concentration m of A x O y Z- Based on the total mass of the electrolyte, 1 ppm to 1000 ppm, optionally 1 ppm to 200 ppm. This can reduce the DCR growth rate of the lithium-ion battery, including the electrolyte, during charge and discharge cycles.

[0011] In some embodiments of this application, the mass concentration n of PO2F2 is - , based on the total mass of the electrolyte, 1 ppm-1000 ppm, optionally 1 ppm-200 ppm. This can reduce the DCR growth rate of the lithium-ion battery, including the electrolyte, during charge and discharge cycles.

[0012] In some embodiments of this application, the electrolyte also contains a film-forming additive. This can reduce the DCR growth rate of the lithium-ion battery, including the electrolyte, during charge and discharge cycles.

[0013] In some embodiments of this application, the mass concentration of the film-forming additive, based on the total mass of the electrolyte, w, and (m+n) / w is 1:(10-100), optionally 1:(20-80). This can reduce the DCR growth rate of the lithium-ion battery, including the electrolyte, during charge and discharge cycles.

[0014] In some embodiments of this application, the mass concentration w of the film-forming additive is 0.2% to 0.5%, optionally 0.25% to 0.45%. This can reduce the DCR growth rate of the lithium-ion battery, including the electrolyte, during charge and discharge cycles.

[0015] In some embodiments of this application, the film-forming additive comprises at least one of the following substances: tris(trimethylsilyl) phosphate, tris(trimethylsilyl) borate, or tris(trimethylsilyl) phosphite. This can reduce the DCR growth rate of the lithium-ion battery, including the electrolyte, during charge and discharge cycles.

[0016] A second aspect of this application provides a battery containing the electrolyte as described in the first aspect. This enables the battery to deliver excellent performance.

[0017] In some embodiments of this application, the battery comprises a positive electrode plate, wherein the active material of the positive electrode of the positive electrode plate satisfies at least one of the following conditions: a volume-based mean particle size D v 50% of the active material of the positive electrode is 1 µm-4 µm, optionally 1 µm-3 µm; the specific BET surface area of ​​the active material of the positive electrode 1 m 2 / g-4 m 2 / g, optional 1 m 2 / g-3 m 2 / g, is and The compressed density of the active material of the positive electrode under a pressure of 300 MPa is 3.2 g / cm³. 3 -3.8 g / cm² 3 , optionally 3.3 g / cm³ 3 -3.6 g / cm² 3 amounts.

[0018] In some embodiments of this application, the battery comprises a negative electrode plate, wherein the active material of the negative electrode of the negative electrode plate satisfies at least one of the following conditions: a volume-based mean particle size D v 50% of the active material of the negative electrode is 1 µm-4 µm, optionally 1 µm-3 µm; a BET-specific surface of the active material of the negative electrode 1 m 2 / g-4 m 2 / g, optional 1 m 2 / g-3 m 2 / g is; and The compressed density of the active material of the negative electrode under a pressure of 300 MPa is 1.4 g / cm³. 3 -1.8 g / cm² 3 , optionally 1.5 g / cm² 3 -1.7 g / cm² 3 amounts.

[0019] A third aspect of this application provides for an electrical device that contains the battery according to the second aspect.

[0020] Further aspects and advantages of this application are partly presented in the following description, partly emerge from the following description, or become clear through the practice of this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Those familiar with the subject matter can clearly recognize various other advantages and benefits from the detailed description of the optional embodiments. The accompanying drawings serve only to illustrate the possible embodiments and are not intended to restrict the present application. Furthermore, the same reference numerals for the same components appear in the accompanying drawings. In the accompanying drawings: Fig. is a schematic structural diagram of a battery according to one embodiment of this application; Fig. is a schematic structure diagram of a battery module according to one embodiment of this application; Fig. is a schematic structure diagram of a battery pack according to one embodiment of this application; Fig. is an exploded view of Fig. ; and Fig.is a schematic diagram of an electrical device that uses a battery as an energy source, according to one embodiment. Description of the signs: 1 secondary battery; 2 battery modules; 3 battery sets; 4 upper housing body; and 5 lower case body. DESCRIPTION OF THE EXECUTION FORMS

[0022] The embodiments of the technical solutions of this application are described in detail below. The following embodiments serve only to clarify the technical solutions of this application and are therefore used only as examples that do not represent any limitations of the scope of protection of this application.

[0023] The reference to "elaboration" in the description means that certain features, structures, or properties described with reference to an embodiment may be included in at least one embodiment of this application. The word "elaboration," appearing at various points in this description, does not necessarily refer to the same embodiment or to an independent or alternative embodiment that excludes other embodiments. Those skilled in the art understand, explicitly and implicitly, that some embodiments described herein may be combined with other embodiments.

[0024] For the sake of brevity, only some numerical ranges are mentioned in this specification. However, any lower bound can be combined with any upper bound to form a range not explicitly recorded; any lower bound can be combined with any other lower bound to form a range not explicitly recorded; and any upper bound can be combined with any other upper bound to form a range not explicitly recorded. Furthermore, any single specified point or numerical value can itself constitute a lower bound or upper bound, which can be combined with any other point or numerical value, or with any other lower bound or upper bound, to form a range not explicitly recorded.

[0025] In the description of the embodiments of this application, the term "and / or" is merely an associative relationship used to describe connected objects, meaning that three relationships are possible. For example, A and / or B can denote the following three cases: the presence of only A, the presence of both A and B, and the presence of only B. Furthermore, the symbol " / " in this specification generally denotes an "or" relationship between the contextually connected objects.

[0026] Unless otherwise defined, the meanings of all technical and scientific terms used in this description correspond to those commonly understood by persons skilled in the art in this application. The terms used in the description of this application serve only to describe certain embodiments, not to limit this application. The terms "comprise," "contain," "have," and all other variations thereof in the description, claims, and short description of the drawings of this application are to be understood as non-exhaustive lists.

[0027] Currently, the applications of lithium-ion batteries are becoming increasingly widespread from a market perspective. Lithium-ion batteries are not only used in energy storage systems such as hydroelectric power plants, thermal power plants, wind turbines, and solar power plants, but also in many other areas, e.g., in electric transportation such as e-bikes, e-motorcycles, and electric vehicles, in military equipment, and in the aerospace industry. With the continuous expansion of the application areas for lithium-ion batteries, market demand for them is also increasing.

[0028] During the charging and discharging of a lithium-ion battery, lithium ions are deintercalated from a positive electrode plate, migrate through an electrolyte to a negative electrode plate under the influence of an electric field, and intercalate into an active material of the negative electrode. During the discharging of the battery, lithium ions deintercalate from the active material of the negative electrode, migrate through the electrolyte to the positive electrode plate under the influence of the electric field, and intercalate into an active material of the positive electrode. During charging and discharging cycles of the secondary battery, side reactions occur between the positive electrode plate and the electrolyte. These side reactions involve active lithium and cause its consumption.On the other hand, the accumulation of side reaction products on the surface of the active material of the positive electrode makes it difficult for lithium ions to be transported, so that they cannot fully intercalate into the material, which ultimately leads to a continuous loss of active lithium in the active material of the positive electrode and causes a continuous increase in the DCR of the lithium-ion battery, thereby reducing the battery's performance.

[0029] In this application, the electrolyte A comprises x O y Z- and PO2F2 - , where A includes at least one of P, S or Si, 1≤x≤2, 4≤y≤5 and 2≤z≤3. Firstly, A can be x O y Z- and PO2F2 -AO bonds, A=O bonds, PO bonds, and P=O bonds are formed. These bonds can bind to lithium ions on the surface of the positive electrode plate, thereby stabilizing the active lithium within the plate. Conversely, A x O y Z- Due to an insufficient binding force of the central ligand A to O under high voltage, electrons are easily lost, and after oxidation, A x O y Z- a film forms on the surface of the positive electrode plate, thereby protecting the active lithium in the positive electrode plate. Furthermore, the P=O bonds on PO₂F₂ are strengthened. -During battery charging, the active material of the positive electrode is easily oxidized after lithium deintercalation on the positive electrode plate. After oxidation of the P=O bonds, the remaining F ions readily combine with lithium ions, thus mitigating the problem of poor ionic conductivity of the surface products after oxidation of A. x O y Z- This effect is mitigated. Since the radii of fluorine ions and lithium ions are similar, their binding energy is high, which allows for good coverage of the fluorine ions on the surface of the positive electrode material and thus reduces the loss of active lithium. Therefore, the use of the electrolyte formulated according to this application can effectively reduce the loss of active lithium, thereby decreasing the DCR growth rate of a battery containing the electrolyte during charge and discharge cycles and improving the battery's performance.

[0030] An electrolyte disclosed in embodiments of this application is applied to a lithium-ion battery, and a battery disclosed in embodiments of this application can be used in electrical devices that use batteries as power sources or in various energy storage systems that use batteries as energy storage elements. Electrical devices include, among others, mobile phones, tablet computers, notebook computers, electric toys, power tools, electric bicycles, electric vehicles, ships, and spacecraft. Electric toys can include stationary or mobile electric toys, such as game consoles, electric toy cars, electric toy ships, and electric toy airplanes. Spacecraft can include airplanes, rockets, space shuttles, spacecraft, and the like.

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

[0032] This application has at least the following positive effects: The electrolyte in this application contains A x O y Z- and PO2F2 - Firstly, A x O y Z- and PO2F2 - AO bonds, A=O bonds, PO bonds, and P=O bonds are formed. These bonds can bind with lithium ions on the surface of a positive electrode plate, thereby stabilizing the active lithium within the plate. Conversely, A x O y Z-Due to an insufficient binding force of the central ligand A to O under high voltage, electrons are easily lost, and after oxidation, A x O y Z- a film forms on the surface of the positive electrode plate, thereby protecting the active lithium in the positive electrode plate. Furthermore, the P=O bonds on PO₂F₂ are strengthened. - During battery charging, after lithium deintercalation on the positive electrode plate, the active material of the positive electrode is readily oxidized. After oxidation of the P=O bonds, the remaining F ions readily combine with lithium ions, thus resolving the problem of poor ionic conductivity of the surface products after oxidation of A. x O y Z-This effect is mitigated. Since the radii of fluorine ions and lithium ions are similar, their binding energy is high, which allows for good coverage of the fluorine ions on the surface of the positive electrode material and thus reduces the loss of active lithium. Therefore, the use of the electrolyte formulated according to this application can effectively reduce the loss of active lithium, lower the DCR growth rate of a battery containing the electrolyte during charge and discharge cycles, and thereby improve the battery's performance.

[0033] In some embodiments of this application, A can be in A x O y Z- It contains at least one of P, S, or Si, 1 ≤ x ≤ 2, 4 ≤ y ≤ 5, and 2 ≤ z ≤ 3. For example, x equals 1 or 2, y equals 4 or 5, and z equals 2 or 3. A x O y Z- For example, at least one of the elements PO4 can 3- , SO4 2- or Si2O5 2-This includes the AO bonds and A=O bonds formed by the A compound formed above. x O y Z- They are provided, interact with lithium ions on the surface of the positive electrode plate, thereby stabilizing the active lithium in the positive electrode plate. Furthermore, A x O y Z- Due to the insufficient binding strength of the central ligand A to O, electrons are easily lost, and after oxidation, A forms x O y Z- a film on the surface of the positive electrode plate, thereby protecting the active lithium in the positive electrode plate. In some other embodiments of this application, A x O y Z- PO4 3- contain.

[0034] It should be noted that in this application A x O y Z- and PO2F2 -the electrolyte in the form of a lithium salt, such as Li3PO4, Li2SO4, Li2Si2O5, and LiPO2F2.

[0035] In some embodiments of this application, the total mass concentration of AxO is, relative to the total mass of the electrolyte, y Z- and P O2 F 2- Less than or equal to 2000 ppm, 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, or 1400 ppm–1500 ppm. Control of the total mass concentration of A x O y Z- and PO2F2 -Therefore, within the electrolyte range mentioned above, not only can the battery's cycle life be extended, but the DCR growth rate of the lithium-ion battery during charge and discharge cycles can also be reduced, thus improving the lithium-ion battery's performance. In some other embodiments of this application, the total mass concentration of A is x O y Z- and PO2F2 - , based on the total mass of the electrolyte, less than or equal to 1500 ppm.

[0036] It should be noted that "ppm" refers to a mass concentration, which is a ratio of the total mass of A x O y Z- and PO2F2 - to the mass of the electrolyte, where 1 ppm = 0.0001%. Furthermore, in this application, the mass concentrations of A can be determined. x O y Z- and PO2F2 -The electrolyte can be tested using instruments and methods known in the industry. For example, the test can be performed using ion chromatography; one instrument is an ICS-900 ion chromatograph, and one test procedure specifically refers to GB / T36240-2018.

[0037] In some embodiments of this application, the mass concentration of A is based on the total mass of the electrolyte. x O y Z- m, the mass concentration of PO2F2 - n, and 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, or (480-500):1. Therefore, in this application, the control of the ratio n / m of the mass concentration n of PO2F2 can be - to mass concentration m of A x O y Z-Within the aforementioned range, gas production in the electrolyte is reduced, and the DCR growth rate of the lithium-ion battery is simultaneously reduced during charge and discharge cycles, thereby improving the performance and cycle life of the lithium-ion battery. In some other embodiments of this application, the mass concentration m of A, relative to the total mass of the electrolyte, is achieved. x O y Z- and the mass concentration n of PO2F2 - the following condition: n / m=(100-500):1.

[0038] In some embodiments of this application, the mass concentration m of A x O y Z-, based on the total mass of the electrolyte, 1 ppm-1000 ppm, for example 2 ppm-1000 ppm, 5 ppm-1000 ppm, 10 ppm-1000 ppm, 50 ppm-1000 ppm, 80 ppm-1000 ppm, 100 ppm-1000 ppm, 120 ppm-1000 ppm, 150 ppm-1000 ppm, 170 ppm-1000 ppm, 200 ppm-1000 ppm, 300 ppm-1000 ppm, 400 ppm-1000 ppm, 500 ppm-1000 ppm, 600 ppm-1000 ppm, 700 ppm-1000 ppm, 800 ppm-1000 ppm, or 900 ppm-1000 ppm. Thus, in this application, the mass concentration of A can be controlled. x O y Z- Within the electrolyte range mentioned above, the DCR growth rate of the lithium-ion battery during charge and discharge cycles is reduced, while simultaneously mitigating the deterioration of gas production, thereby improving the power and cycle performance of the lithium-ion battery. In some other embodiments of this application, the mass concentration m of A x O y Z- , relative to the total mass of the electrolyte, 1 ppm-200 ppm.

[0039] In some embodiments of this application, the mass concentration n of PO2F2 is - , based on the total mass of the electrolyte, 1 ppm-1000 ppm, for example 2 ppm-1000 ppm, 5 ppm-1000 ppm, 10 ppm-1000 ppm, 50 ppm-1000 ppm, 80 ppm-1000 ppm, 100 ppm-1000 ppm, 120 ppm-1000 ppm, 150 ppm-1000 ppm, 170 ppm-1000 ppm, 200 ppm-1000 ppm, 300 ppm-1000 ppm, 400 ppm-1000 ppm, 500 ppm-1000 ppm, 600 ppm-1000 ppm, 700 ppm-1000 ppm, 800 ppm-1000 ppm, or 900 ppm-1000 ppm. Thus, in this application, the mass concentration of PO₂F₂ can be controlled. - Within the electrolyte range mentioned above, the DCR growth rate of the lithium-ion battery during charge and discharge cycles is reduced, thereby improving the performance of the lithium-ion battery. In some other embodiments of this application, the mass concentration n of PO2F2 is - , relative to the total mass of the electrolyte, 1 ppm-200 ppm.

[0040] In some embodiments of this application, the electrolyte may also contain a film-forming additive. The term "film-forming additive" refers in particular to a substance added to the electrolyte to facilitate the formation of a CEI (cathode electrolyte interphase) film on the surface of a positive electrode plate and / or a SEI (solid electrolyte interphase) film on the surface of a negative electrode plate. The film-forming additive added to the electrolyte in this application, in synergy with AxO, facilitates y Z- and P O2 F2 - The film formation on the surface of the positive electrode plate effectively reduces the loss of active lithium, thereby decreasing the DCR growth rate of the battery including the electrolyte during charge and discharge cycles and improving the battery's performance.

[0041] In some embodiments of this application, the mass concentration of the film-forming additive w is based on 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), or 1:(55-60). Therefore, in this application, controlling the ratio of the total mass concentration of A x O y Z- and PO2F2 - By reducing the mass concentration of the film-forming additive in the electrolyte within the aforementioned range, the DCR growth rate of the lithium-ion battery during charge and discharge cycles is reduced, thereby improving the performance of the lithium-ion battery. In some other embodiments of this application, the mass concentration m of A is sufficient. x O y Z- , the mass concentration n of PO2F2 -and the mass concentration w of the film-forming additive: (m+n) / w is 1:(20-80).

[0042] In some embodiments of this application, the mass concentration w of the film-forming additive is 0.2% to 0.5%, for example, 0.22% to 0.48%, 0.25% to 0.45%, 0.27% to 0.42%, 0.3% to 0.4%, 0.32% to 0.38%, or 0.35% to 0.37%. Thus, in this application, controlling the mass concentration w of the film-forming additive in the electrolyte within the aforementioned range can reduce the DCR growth rate of the lithium-ion battery during charge and discharge cycles, thereby improving the 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% to 0.45%.

[0043] It should be noted that in this application the concentration of the film-forming additive in the electrolyte can be checked using instruments and methods known in the trade, e.g. organic gas chromatography.

[0044] The film-forming additive may, for example, contain at least one of the following products: Tris(trimethylsilyl)phosphate, Tris(trimethylsilyl)borate or Tris(trimethylsilyl)phosphite.

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

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

[0047] For example, the solvent may contain 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), gamma-butyrolactone (GBL), sulfolane (SF), methylsulfonylmethane (MSM), ethyl methyl sulfone (EMS), or ethylsulfonyl ethane (ESE).

[0048] In some embodiments, the electrolyte may also contain an additive that can improve a certain performance of the battery, e.g. an additive to improve the overcharge performance of the battery, an additive to improve the high temperature performance of the battery, or an additive to improve the low temperature performance of the battery.

[0049] A second aspect of this application provides a battery containing the electrolyte as described in the first aspect. This enables the battery to have low DC resistance and excellent performance.

[0050] The term "battery" refers to a battery whose active material can be reactivated for continuous use by recharging after the battery has been discharged.

[0051] A battery typically contains a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. During charging and discharging, active ions intercalate and deintercalate between the positive and negative electrode plates. The separator is positioned between the positive and negative electrode plates to keep them apart. The electrolyte conducts ions between the positive and negative electrode plates.

[0052] In some embodiments of this application, the battery can be a lithium-ion battery. [Positive electrode plate]

[0053] In the battery, the positive electrode plate typically comprises a positive electrode current collector and a positive electrode active material layer arranged on the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material.

[0054] The current collector of the positive electrode can be a conventional metal foil or a composite current collector (e.g., a metal material can be arranged on a polymer substrate to form a composite current collector). For example, an aluminum foil can be used as a current collector for the positive electrode.

[0055] The type of active material for the positive electrode is not restricted. Any active material known in the field of technology and used for the positive electrode of a secondary battery can be used, and experts can make a selection according to the actual needs.

[0056] The active material for the positive electrode can, for example, comprise at least one of the following materials: lithium transition metal oxide, lithium-containing phosphate with an olivine structure, or corresponding modified compounds thereof, but is not limited to these. Examples of lithium transition metal oxides include 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 modified compounds thereof. Examples of lithium-containing phosphates with an olivine structure include lithium iron phosphate, a lithium iron phosphate-carbon compound, lithium manganese phosphate, a lithium manganese phosphate-carbon compound, lithium iron manganese phosphate, a lithium iron manganese phosphate-carbon compound, and modified compounds thereof.These materials are all commercially available.

[0057] In some embodiments of this application, the volume-based mean particle size D is v 50 of the active material of the positive electrode 1 µm-4 µm. The volume-related mean particle size D v The active material of the positive electrode can, for example, be 1–3 µm or 2–3 µm. In some other embodiments of this application, the volumetric mean particle size D is... v 50 of the active material of the positive electrode 1 µm-3 µm.

[0058] In this application, the volume-related mean particle size D refers to v 50 to a corresponding particle size when the cumulative volume fraction reaches 50%. For example, the volume-based mean particle size D v 50 tested according to standard GB / T 19077-2016 using a laser particle size measuring device (e.g. Malvern Master Size 3000).

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

[0060] In this application, the specific surface area of ​​the active material of the positive electrode can be tested using the following method: Approximately 7 g of a sample is placed in a 9 cm² chamber using a fully automated Micromeritics multi-station analyzer for specific surface area and porosity, Gemini VII2390. 3A long tube was placed with a piston, degassed for 2 hours at 200 °C, and then the sample was placed in a main instrument for testing to obtain the BET (specific surface area) data of the active material of the positive electrode.

[0061] In some embodiments of this application, the compressed density of the active material of the positive electrode under a pressure of 300 MPa is 3.2 g / cm³. 3 -3.8 g / cm² 3 For example, the compressed density of the active material of the positive electrode at a pressure of 300 MPa can be 3.2 g / cm³. 3 -3.7 g / cm² 3 , 3.3 g / cm³ 3 -3.6 g / cm² 3 or 3.4 g / cm³ 3 -3.5 g / cm² 3 In some embodiments of this application, the compressed density of the active material of the positive electrode under a pressure of 300 MPa is 3.3 g / cm³. 3 -3.6 g / cm² 3 .

[0062] In this application, "compressed density" has the meaning known in engineering and can be tested using instruments and methods known in engineering, for example using the following test procedure: A quantitative mass m of powder is placed in a special compression mold, the mold is placed on a compressed density device, a pressure of 300 MPa is set, a volume v of powder under the pressure of 300 MPa is tested on the device, and the compressed density is calculated as density = mass m / volume v (in particular with reference to GB / T24533-2009).

[0063] In particular, if at least one of the volume-based mean particle size D v50, the specific surface area or the compressed density under a pressure of 300 MPa of the active material of the positive electrode of this application lies within the above-mentioned ranges, a conduction path within the active material of the positive electrode is short and there are few side reactions at the surface, which helps the active material of the positive electrode to exert its specific capacity and increases the capacity retention rate of a battery containing the active material of the positive electrode. [Negative electrode plate]

[0064] In the battery, the negative electrode plate typically comprises a negative electrode current collector and a layer of negative electrode active material arranged on the negative electrode current collector, wherein the layer of negative electrode active material comprises a negative electrode active material.

[0065] The current collector for the negative electrode can be a conventional metal foil or a composite current collector (e.g., a metal material can be arranged on a polymer substrate to form a composite current collector). For example, a copper foil can be used as a current collector for the negative electrode.

[0066] The type of active material for the negative electrode is not restricted. Any active material known in the field of engineering and used for the negative electrode of a secondary battery can be used, and experts can make a selection according to the actual requirements. For example, the active material for the negative electrode can include, but is not limited to, synthetic graphite, natural graphite, hard carbon, soft carbon, a silicon-based material, or a tin-based material. The silicon-based material can include at least one of elemental silicon, a silicon-oxygen compound (e.g., silicon monoxide), a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can include at least one of elemental tin, a tin-oxygen compound, and a tin alloy.These materials are all commercially available.

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

[0068] In some embodiments of this application, the volume-based mean particle size D is v 50 of the active material of the negative electrode 1 µm-4 µm. The volume-related mean particle size D v The active material of the negative electrode can, for example, be 1–3 µm or 2–3 µm. In some other embodiments of this application, the volumetric mean particle size D is... v 50 of the active material of the negative electrode 1 µm-3 µm.

[0069] In this application, the meaning and testing procedure of the volume-based mean particle size D can be explained. v50 of the active material of the negative electrode on the significance and the test method of the volume-based mean particle size D v 50 of the active material of the positive electrode.

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

[0071] In this application, the test procedure for the specific BET surface of the active material of the negative electrode can refer to the test procedure for the specific BET surface of the active material of the positive electrode.

[0072] In some embodiments of this application, the compacted density of the negative electrode plate is 1.4 g / cm³. 3 -1.8 g / cm² 3 , for example 1.4 g / cm³ 3 -1.7 g / cm² 3 , 1.5 g / cm³ 3 -1.7 g / cm² 3 or 1.6 g / cm³ 3 -1.7 g / cm² 3 In some other embodiments of this application, the compacted density of the negative electrode plate is 1.5 g / cm³. 3 -1.7 g / cm² 3 This can improve the cycle stability of the battery, including the negative electrode plate.

[0073] In this application, the "density of the negative electrode plate" has a well-established meaning in engineering and can be tested using established instruments and methods. The test procedure can, for example, be based on the test method described above for the "density of the positive electrode plate." A negative electrode is typically cleaned with deionized water to remove an active material layer.

[0074] The layer of active material for the negative electrode typically also contains a binder, a conductive agent, and other optional additives.

[0075] The conductive material can include, for example, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0076] The binder may contain, for example, at least one of the following materials: 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] Other optional additives may include, for example, a thickening agent, a dispersing agent (e.g., sodium carboxymethylcellulose CMC-Na), and a PTC thermistor material.

[0078] The aforementioned separator is not particularly limited in this application, and any known porous separator with electrochemical and mechanical stability can be used, depending on the actual requirements. The separator can, for example, contain a single- or multi-layer film incorporating at least one of the following materials: fiberglass, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0079] The shape of the battery is not particularly limited in the embodiments of this application, and the battery can be cylindrical, rectangular, or in any other shape. Fig. Figure 1 shows, as an example, a secondary battery 1 with a rectangular structure.

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

[0081] In some embodiments, the outer packaging may comprise a housing and a cover plate. The housing may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving space. The housing has an opening that connects to the receiving space, and the cover plate may cover the opening to close the receiving space.

[0082] The positive electrode plate, the negative electrode plate, and the separator can be formed into an electrode assembly using a winding or lamination process. The electrode assembly is then packaged in the receiving compartment. The battery can contain one or more electrode assemblies, the number of which can be adjusted as needed.

[0083] In some embodiments, the outer packaging of the battery may include a hard shell, e.g., a hard plastic shell, an aluminum shell, or a steel shell.

[0084] The outer packaging of the battery can alternatively include soft packaging, such as a soft bag. The material of the soft packaging can be plastic, for example, at least one of the following materials: polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0085] In some embodiments, the battery can be assembled into a battery module, the battery module being able to consist of several batteries and the specific quantity being able to be adjusted depending on the application and capacity of the battery module.

[0086] Fig. shows, as an example, a battery module 2. As in Fig. As shown, several secondary batteries 1 can be arranged one behind the other in the longitudinal direction of battery module 2. Of course, the secondary batteries can also be arranged in any other way. Furthermore, the majority of the secondary batteries 1 can be fixed in place by fastening elements.

[0087] The battery module 2 can further comprise a housing with a receiving compartment in which the multiple secondary batteries 1 are accommodated. In some embodiments, the battery module can be further assembled into a battery pack, the number of battery modules in the battery pack being adaptable depending on the application and capacity of the battery pack.

[0088] Fig. and Fig. As an example, we show a battery pack 3. As in Fig. and Fig. As shown, the battery pack 3 can comprise a battery box and a plurality of battery modules 2 arranged within the battery box. The battery box comprises an upper box body 4 and a lower box body 5, the upper box body 4 being adapted to the lower box body 5 to form an enclosed space for receiving the battery modules 2. The multiple battery modules 2 can be arranged within the battery box in any desired configuration.

[0089] A third aspect of this application involves an electrical device that contains the battery as described in the second aspect. Specifically, the battery can serve as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device can be, but is not limited to, a mobile device (e.g., a mobile phone or a laptop computer), an electric vehicle (e.g., a battery-powered electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, or an electric truck), an electric train, a ship, a satellite, or an energy storage system.

[0090] Fig. shows an electrical device as an example. The electrical device includes a battery-powered electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0091] As another example, the electrical device could include a mobile phone, a tablet computer, or a notebook computer. Such an electrical device generally needs to be lightweight and thin and can use a battery as a power source.

[0092] To more clearly describe the technical problems solved by the embodiments of this application, the technical solutions, and the advantageous effects, this application is described in detail below with reference to the embodiments and the accompanying drawings. Obviously, the embodiments described represent only some, and not all, embodiments of this application. The following description of at least one exemplary embodiment serves only for illustration and is in no way to be understood as limiting this disclosure or its use. All other embodiments that can be achieved by those skilled in the art based on the embodiments of this application without creative effort fall within the scope of protection of this application. Example 11. Preparation of the positive electrode plate

[0093] An active material for the positive electrode LiNi 0,7 Co 0,1 Mn 0,1 O2, a conductive agent Super P and a binder polyvinylidene fluoride (PVDF) were added to N-methylpyrrolidone (NMP) to produce a positive electrode paste, wherein the solids content of the positive electrode paste was 50 wt% and the mass ratio of LiNi 0,7 Co 0,1 Mn 0,1 The solid components consisted of O2, Super P, and PVDF in an 8:1:1 ratio. The positive electrode paste was applied to the top and bottom surfaces of an aluminum foil for the current collector, dried at 85 °C, and cold-pressed. The plate for the positive electrode was then trimmed, cut, and slotted, and subsequently vacuum-dried at 85 °C for 4 hours. 3. Preparation of the negative electrode plate

[0094] Graphite, a conductive agent (Super P), a thickening agent (carboxymethylcellulose, CMC), and a binder (styrene-butadiene rubber, SBR) were thoroughly mixed in deionized water to produce a negative electrode paste. The solids content of the negative electrode paste was 30 wt%, and the mass ratio of graphite, silicon monoxide, Super P, CMC, and the binder (styrene-butadiene rubber, SBR) in the solids was 88:7:3:2. The negative electrode paste was applied to the top and bottom surfaces of a copper foil for the current collector and dried at 85 °C. Subsequently, the negative electrode plate was produced by cold pressing, trimming, cutting, slitting, and subsequent vacuum drying at 120 °C for 12 h. 3. Preparation of the electrolyte

[0095] Li were placed in a glove box filled with argon (water content <10 ppm, oxygen content <1 ppm). z A x O yLiPO₂F₂ was added to an organic solvent (containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a mass ratio of EC to EMC of 3:7) and then mixed thoroughly. LiPF₆ and LiFSI were then slowly added. After the lithium salts were completely dissolved, an electrolyte with a lithium salt concentration of 1 mol / L was obtained. 4. Separator

[0096] A polyethylene film with a thickness of 16 µm was used as a separator. 5. Preparing the lithium-ion battery

[0097] The positive electrode plate, separator, and negative electrode plate were stacked sequentially, with the separator positioned between them. The resulting stack was then wound into a gel-like roll. The flaps were welded shut, and the gel-like roll was placed in an outer packaging. The prepared electrolyte was injected into the dried gel-like roll, and processes such as packaging, curing, molding, formatting, and capacity testing were performed to complete the manufacture of a lithium-ion battery (a soft-pack lithium-ion battery measuring 4.0 mm thick, 60 mm wide, and 140 mm long).

[0098] The manufacturing processes of the lithium-ion batteries of Examples 2 to 39 and of the comparative examples 1 to 4 were the same as the manufacturing processes of the lithium-ion battery of Example 1, except that the compositions of the additives in the electrolytes were different, the details of which are set out in Table 1. Table 1

[0099] The DCR growth rates of the lithium-ion batteries obtained in Examples 1 to 39 and Comparison Examples 1 to 4 were characterized, with the characterization results listed in Table 2. Test procedure for the DCR growth rate of lithium-ion batteries

[0100] Before cycling the battery, the state of charge (SOC) was set to 50%. The battery was then discharged for 30 seconds at 4°C. The pre-discharge voltage was designated V1 and the post-discharge voltage V2. The calculation was performed to obtain DCR1 = (V1 - V2) / I (one value of I corresponding to a current value for the discharge at 4°C). After 300 cycles, the battery was removed. DCR2 was tested using the same solution, and a calculation was performed to obtain ΔDCR = (DCR2 - DCR1) / DCR1, where ΔDCR was the DCR growth rate of the battery. Table 2 DCR growth rate (%) Example 1 18,7 Example 2 18,9 Example 3 19,1 Example 4 21,3 Example 5 21,5 Example 6 21,7 Example 7 23,1 Example 8 23 Example 9 23,5 Example 10 19,3 Example 11 19,2 Example 12 19,3 Example 13 19,1 Example 14 21,4 Example 15 21,6 Example 16 21,7 Example 17 18,8 Example 18 18,7 Example 19 18,8 Example 20 18,6 Example 21 18,6 Example 22 18,5 Example 23 18,7 Example 24 18,6 Example 25 16,3 Example 26 16,5 Example 27 16,2 Example 28 17,9 Example 29 16,7 Example 30 16,7 Example 31 16,6 Example 32 16,3 Example 33 16,1 Example 34 17,7 Example 35 16,8 Example 36 14,5 Example 37 14,4 Example 38 14,2 Example 39 16,9 Comparative example 1 29,4 Comparative example 2 27,3 Comparative example 3 25,8 Comparative example 4 24,7

[0101] Table 2 shows that the DCR growth rates of the lithium-ion batteries in examples 1 to 39 are significantly lower than those in the comparison examples 1 to 4, indicating that the electrolyte in this application, including A x O y Z- and PO2F2 -, which can effectively reduce the DCR growth rate of the battery, including the electrolyte, during charging and discharging cycles, thereby improving the performance of the lithium-ion battery.

[0102] Finally, it should be noted that the embodiments mentioned above serve only to describe the technical solutions of this application, not to limit it. Although this application is described in detail with reference to the embodiments above, persons with ordinary technical knowledge should understand that they may still make modifications to the technical solutions described in the embodiments above, or make equivalent substitutions to some or all of their technical features, without altering the scope of the technical solutions of the embodiments of this application. All such modifications and equivalent substitutions must fall within the scope of the claims and the specification of this application.In particular, the various technical features mentioned in the exemplary embodiments can be combined arbitrarily, as long as there is no structural conflict. This application is not limited to the specific embodiments disclosed in this description, but encompasses all technical solutions that fall within the scope of the claims. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] Standard GB / T 19077-2016

[0058] GB / T24533-2009

[0062]

Claims

An electrolyte comprising: AxOyZ- and PO2F2-, wherein A comprises at least one of P, S or Si, 1≤x≤2, 4≤y≤5 and 2≤z≤3. The electrolyte according to claim 1, wherein AxOyZ comprises at least one of the elements PO43-, SO42- or Si2O52-. The electrolyte according to claim 1 or 2, comprising AxOyZ-PO43. The electrolyte according to any one of claims 1 to 3, wherein, based on the total mass of the electrolyte, the total mass concentration of AxOyZ and PO2F2 is less than or equal to 2000 ppm. The electrolyte according to any one of claims 1 to 4, wherein, based on the total mass of the electrolyte, the total mass concentration of AxOyZ and PO2F2 is less than or equal to 1500 ppm. The electrolyte according to any one of claims 1 to 5, wherein, based on the total mass of the electrolyte, the mass concentration of AxOyZ-m, the mass concentration of PO2F2-n and n / m=(10-1000):1 is. The electrolyte according to claim 6, wherein n / m=(100-500):

1. The electrolyte according to claim 6 or 7, wherein, based on the total mass of the electrolyte, the mass concentration m is from AxOyZ-1 ppm-1000 ppm. The electrolyte according to any one of claims 6 to 8, wherein, based on the total mass of the electrolyte, the mass concentration m is from AxOyZ-1 ppm-200 ppm. The electrolyte according to any one of claims 6 to 9, wherein, based on the total mass of the electrolyte, the mass concentration n of PO2F2-1 ppm-1000 ppm is. The electrolyte according to any one of claims 6 to 10, wherein, based on the total mass of the electrolyte, the mass concentration n is PO2F2-1 ppm-200 ppm. The electrolyte according to any one of claims 6 to 11, wherein the electrolyte further comprises a film-forming additive. The electrolyte according to claim 12, wherein, based on the total mass of the electrolyte, the mass concentration of the film-forming additive is w and (m+n) / w is 1:(10-100). The electrolyte according to claim 13, wherein (m+n) / w is 1:(20-80). The electrolyte according to claim 13 or 14, wherein the mass concentration w of the film-forming additive is 0.2 to 0.5%. 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%. 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(trimethylsilyl) borate or tris(trimethylsilyl) phosphite. A battery containing the electrolyte according to any one of claims 1 to 17. The battery according to claim 18, wherein the battery comprises a lithium-ion battery. The battery according to claim 18 or 19, wherein the battery has a positive electrode plate and an active material of the positive electrode of the positive electrode plate meets at least one of the following conditions: a volume-related mean particle size Dv50 of the active material of the positive electrode is 1 µm-4 µm; a specific BET surface area of ​​the active material of the positive electrode is 1 m2 / g-4 m2 / g; and the compressed density of the active material of the positive electrode under a pressure of 300 MPa is 3.2 g / cm3-3.8 g / cm3. The battery according to any one of claims 18 to 20, wherein the battery comprises a negative electrode plate and an active material of the negative electrode of the negative electrode plate meets at least one of the following conditions: a volume-related mean particle size Dv50 of the active material of the negative electrode is 1 µm-4 µm; a specific BET surface area of ​​the active material of the negative electrode is 1 m2 / g-4 m2 / g; and the compressed density of the active material of the negative electrode under a pressure of 300 MPa is 1.4 g / cm3-1.8 g / cm3. An electrical device comprising the battery according to any one of claims 18 to 21.

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