Positive electrode active material, method for manufacturing the same, positive electrode sheet, battery, and electric device

Abstract

The application provides a positive electrode active material, a preparation method thereof, a positive electrode sheet, a battery and an electric device. The positive electrode active material comprises (1-a)LiNi x M1 y M2 (1‑x‑y‑z) Nb z O2·aLi2MnO3; M1 comprises one or both of Mn and Al; M2 comprises one or more of transition metal elements other than Mn elements, Ni elements and Nb elements. The positive electrode active material can improve the cycle stability and the battery capacity after the cycle of the battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium secondary batteries, in particular to a positive electrode active material, a preparation method of the positive electrode active material, a positive electrode sheet, a battery and a power utilization device. BACKGROUND

[0002] In recent years, with the increasingly wide application of lithium secondary batteries, lithium secondary batteries are widely used in energy storage power supply systems such as hydraulic, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. Since lithium secondary batteries have achieved great development, the cycle performance and capacity of the battery need to be improved. SUMMARY

[0003] The present application is carried out in view of the above-mentioned problems, and aims to provide a positive electrode active material, a preparation method of the positive electrode active material, a positive electrode sheet, a battery and a power utilization device. The positive electrode active material of the present application improves the cycle stability and the capacity of the battery after cycling.

[0004] To achieve the above-mentioned purpose, the present application provides a positive electrode active material in the first aspect, which comprises (1-a) LiNi x M1 y M2 (1-x-y-z) Nb z O2·aLi2MnO3; wherein,

[0005] M1 comprises one or both of Mn and Al elements;

[0006] M2 comprises one or more of transition metal elements other than Mn elements, Ni elements and Nb elements;

[0007] 0 < a < 1; 0.6 ≤ x < 1, 0 ≤ y < 0.4, 0 < z ≤ 0.15, and 0.6 < x + y + z ≤ 1.

[0008] Although the conventional lithium-rich manganese-based positive electrode active material has a high theoretical capacity, with the progress of battery charging and discharging cycles, part of the Li2MnO3 phase decomposes, resulting in rapid decay of the battery capacity after cycling.

[0009] The present application dopes a proper amount of Nb element and optionally dopes M1 element and M2 element in the lithium-rich manganese-based positive electrode active material, which is beneficial to improve the material particle crushing condition, stabilize the material lattice structure, improve the cycle stability of the battery, thereby inhibiting the decay of the battery capacity after cycling and improving the battery capacity after cycling. Furthermore, the present application further improves the battery capacity by increasing the content of Ni element.

[0010] In any embodiment, 4≤x / z≤14, optionally 6≤x / z≤10. In this way, the content ratio of Ni and Nb in the solid solution is within a certain range, which is beneficial to improve the cycle stability and capacity of the battery, thereby improving the battery capacity after cycling.

[0011] In any embodiment, 0.7≤x≤0.85. In this way, the cycle stability and capacity of the battery are improved, thereby improving the battery capacity after cycling.

[0012] In any embodiment, 0.05≤z≤0.15, optionally 0.1≤z≤0.15. In this way, the cycle stability and capacity of the battery are improved, thereby improving the battery capacity after cycling.

[0013] In any embodiment, 0.05≤a≤0.6, optionally 0.1≤a≤0.5. In this way, the solid solution of the lithium-rich manganese-based positive electrode active material contains a certain proportion of the relatively stable layered LiNi x M1 y M2 (1-x-y-z) Nb z O2 and Li2MnO3 with high lithium content and high capacity, thereby improving the cycle stability and capacity of the battery, and improving the battery capacity after cycling.

[0014] In any embodiment, M2 includes one or more of Co, Mo and Zr; optionally, M2 includes a Co element. In this way, doping the M2 element is beneficial to improve the cycle stability of the battery.

[0015] In any embodiment, the positive electrode active material includes a polycrystalline material, and the primary particles of the polycrystalline material have a particle size of greater than or equal to 0.1 μm and less than or equal to 1.5 μm, optionally greater than 0.3 μm and less than or equal to 1.5 μm, more optionally greater than or equal to 0.4 μm and less than or equal to 1 μm. In this way, during the charging and discharging cycle of the battery, the degree of material volume change can be reduced, and the degree of particle breakage can be reduced, thereby improving the cycle stability of the battery.

[0016] In any embodiment, the volume average particle size Dv50 of the positive electrode active material is 1-10 μm; and / or,

[0017] The specific surface area of the positive electrode active material is 0.2-2 m 2 / g; and / or,

[0018] The tap density of the positive electrode active material is 1.5-2.5 g / cm 3 .

[0019] The second aspect of the present application also provides a method for preparing a positive electrode active material, comprising the following steps:

[0020] A solution containing a nickel source is provided, and the solution can also optionally contain a source of M1 element and / or a source of M2 element;

[0021] The solution is reacted with an alkali solution to obtain a precipitate;

[0022] The precipitate is mixed with a lithium source and a niobium source, and is calcined to obtain a positive electrode active material;

[0023] The positive electrode active material comprises (1-a)LiNi x M1 y M2 (1-x-y-z) Nb z O2·aLi2MnO3, wherein M1, M2, a, x, y and z are defined as described in the first aspect of the present application.

[0024] Therefore, by doping an appropriate amount of Nb element and optionally doping M1 element and M2 element, the present application can improve the material particle breakage, stabilize the material crystal lattice structure, improve the cycle stability of the battery, thereby inhibiting the capacity attenuation of the battery after cycling and improving the capacity of the battery after cycling. Furthermore, the present application further improves the battery capacity by increasing the content of Ni element. Moreover, the method of the present application is simple, efficient and safe, and has strong operability and adaptability, and is convenient for large-scale production.

[0025] In any embodiment, the molar ratio of the nickel element in the solution to the niobium element in the niobium source is 4-14, which can be 6-10.

[0026] In any embodiment, the content of the nickel element in the solution is 0.1-1 mol / L, which can be 0.2-0.8 mol / L; and / or,

[0027] The content of the M1 element in the solution is 0-0.9 mol / L, which can be 0-0.7 mol / L; and / or,

[0028] The content of the M2 element in the solution is 0-0.3 mol / L, which can be 0-0.1 mol / L.

[0029] In any embodiment, the molar ratio of the lithium element in the lithium source to the niobium element in the niobium source is 7-32, which can be 10-22.

[0030] In any embodiment, the alkali solution comprises sodium hydroxide and / or NH3·H2O; and / or,

[0031] The calcination temperature is 700-800°C; and / or,

[0032] The calcination time is 4-15 hours.

[0033] The third aspect of the present application provides a positive electrode tab comprising the positive electrode active material of the first aspect of the present application or the positive electrode active material prepared by the method of the second aspect of the present application.

[0034] The fourth aspect of the present application provides a battery comprising the positive electrode active material of the first aspect of the present application, the positive electrode active material prepared by the method of the second aspect of the present application or the positive electrode tab of the third aspect of the present application.

[0035] In any embodiment, the battery can include, but is not limited to, a product form of a secondary battery, a battery module, a battery pack.

[0036] The fifth aspect of the present application provides an electric device comprising the battery of the fourth aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.

[0038] Figure 2 is a schematic diagram of a secondary battery according to an embodiment of the present application. Figure 1

[0039] Figure 3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0040] Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0041] Figure 5 is a schematic diagram of a battery pack according to an embodiment of the present application. Figure 4

[0042] Figure 6 is a schematic diagram of an electric device using a secondary battery according to an embodiment of the present application as a power source.

[0043] BRIEF DESCRIPTION OF DRAWINGS

[0044] 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 secondary battery; 51 case; 52 electrode assembly; 53 top cap assembly. DETAILED DESCRIPTION

[0045] ​​Hereinafter, specific embodiments of the positive electrode active material and the method for manufacturing the same, the positive electrode sheet, the secondary battery, the battery module, the battery pack, and the power storage device of the present application will be described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed description is omitted. For example, there will be cases where detailed description of matters known well, repeated description of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0046] The ranges disclosed herein are defined by their lower and upper limits. Ranges can be inclusive or exclusive of their endpoints, and all ranges and sub-ranges are combinable. For example, if a range is listed as 60-120 and 80-110, it is understood that 60-110 and 80-120 are also expressly stated. Also, if a range is listed as 1-2 and 3-5, it is understood that 1-5, 1-3, 2-5, and 2-3 are also expressly stated. In the present application, unless otherwise indicated, a numerical range "a-b" is intended to indicate any and all sub-ranges of the same, including the end values and excluding the end values. For example, numerical ranges "0-5" is intended to indicate the full set of all real numbers between "0" and "5", inclusive of "0" and "5", and is simply a shorthand way of referring to such a range. Additionally, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0047] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0048] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0049] If not specifically stated, all steps of the present application can be performed in sequence or randomly, and preferably in sequence. For example, a method comprising steps (a) and (b) indicates that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, a method can further comprise step (c) indicates that step (c) can be added to the method in any order. For example, a method can comprise steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), and so on.

[0050] If not specifically stated, "comprising" and "including" as used in the present application are open-ended and also can be closed. For example, "comprising" and "including" can mean that other components not listed can also be included or can mean that only the listed components are included.

[0051] If not specifically stated, in the present application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following conditions satisfy the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0052] If not specifically stated, in the present application, the term "solid solution" is a homogeneous mixture of multiple crystalline solids that share a common crystal lattice. A solid solution is typically composed of multiple atoms or molecules that share a crystal lattice. LiNi x M1 y M2 (1-x-y-z) Nb z O2 and Li2MnO3 have a common crystal lattice structure.

[0053] If not specifically stated, in the present application, the term "volume average particle size Dv50" is the particle size at which 50% of the volume is accumulated from the small particle size side in a particle size distribution on a volume basis.

[0054] [Secondary battery]

[0055] A secondary battery, also referred to as a rechargeable battery or accumulator, is a battery that can be used continuously after activation of the active material by charging after discharging of the battery.

[0056] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During charging and discharging of the battery, active ions (e.g., lithium ions) are intercalated and deintercalated between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet and mainly functions to prevent short circuiting of the positive and negative electrodes while allowing the active ions to pass through. The electrolyte is between the positive electrode sheet and the negative electrode sheet and mainly functions to conduct the active ions.

[0057] [Positive active material]

[0058] One embodiment of the present application provides a positive active material including (1-a)LiNi x M1 y M2 (1-x-y-z) Nb z O2·aLi2MnO3; wherein,

[0059] M1 includes one or both of Mn and Al;

[0060] M2 includes one or more of transition metal elements other than Mn elements, Ni elements, and Nb elements;

[0061] a is generally greater than 0 and less than 1; x is generally greater than or equal to 0.6 and less than 1; y is generally greater than or equal to 0 and less than 0.4; z is generally greater than 0 and less than or equal to 0.15; and the sum of x, y, and z is greater than 0.6 and less than or equal to 1.

[0062] It should be noted that, in the composition formula of the positive active material, the atomic ratio of oxygen is recorded as 2 or 3 for convenience, but there can be a certain non-stoichiometry. In addition, in the composition formula of the positive active material, the element molar ratio is the feeding ratio at the manufacturing stage.

[0063] Although the conventional lithium-rich manganese-based positive active material has a high theoretical capacity, as the battery charging and discharging cycle progresses, part of the Li2MnO3 phase decomposes, resulting in rapid capacity decay of the battery after cycling.

[0064] Although the mechanism is not clear, the present applicant has unexpectedly found that the present application, by doping an appropriate amount of Nb elements and optionally doping M1 elements and M2 elements, is beneficial to improve the material crushing condition, stabilize the material lattice structure, improve the cycle stability of the battery, thereby inhibiting the capacity decay of the battery after cycling and improving the capacity of the battery after cycling. Furthermore, the present application further improves the battery capacity by increasing the content of Ni elements.

[0065] In some embodiments, 4≤x / z≤14, optionally 6≤x / z≤10, for example x / z is 4, 4.5, 5, 5.5, 6, 6.4, 7, 7.6, 8, 8.4, 9, 9.6, 10, 10.5, 11, 11.4, 12, 12.3, 13, 13.5, 14, and any range of values between the values listed above. In this way, the content ratio of Ni and Nb in the solid solution is within a certain range, which is beneficial to improve the cycle stability and capacity of the battery, thereby improving the battery capacity after cycling.

[0066] In some embodiments, 0.7≤x≤0.85, for example 0.7, 0.73, 0.8, 0.85, and any range of values between the values listed above. In this way, the cycle stability and capacity of the battery are improved, thereby improving the battery capacity after cycling.

[0067] In some embodiments, 0.05≤z≤0.15, optionally 0.1≤z≤0.15, for example 0.05, 0.07, 0.1, 0.12, 0.15, and any range of values between the values listed above. In this way, the cycle stability and capacity of the battery are improved, thereby improving the battery capacity after cycling.

[0068] In some embodiments, 0.05≤a≤0.6, optionally 0.1≤a≤0.5, for example a is 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and any range of values between the values listed above. In this way, the solid solution of the lithium-rich manganese-based positive electrode active material contains a certain proportion of the relatively stable layered LiNi x M1 y M2 (1-x-y-z) Nb z O2 and Li2MnO3 with higher lithium content and higher capacity, which improves the cycle stability and capacity of the battery, and improves the battery capacity after cycling.

[0069] In some embodiments, the battery in the market is usually aged after assembly. After the battery is aged, part of the layered Li2MnO3 phase can be converted into a molten salt phase LiMn2O4 in the voltage range above 4.5V. At this time, in the composition analysis, 0

[0070] In some embodiments, M2 includes one or more of Co, Mo, and Zr; optionally, M2 includes a Co element. In this way, doping the M2 element is beneficial to improve the cycle stability of the battery.

[0071] In some embodiments, the positive electrode active material includes a solid solution (1-a)LiNi x M1 y M2 (1-x-y-z) Nb zO2·aLi2MnO3; wherein M1, M2, a, x, y, and z are defined as described herein before.

[0072] In some embodiments, the volume average particle size Dv50 of the positive electrode active material is 1-10 μm, for example, can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, and a range consisting of any of the above-mentioned values.

[0073] In some embodiments, the volume average particle size Dv50 is tested by Mastersizer 3000 laser particle size instrument according to the method in national standard GB / T 19077-2016.

[0074] In some embodiments, the positive electrode active material comprises a polycrystalline material, and the particle size of the primary particles of the polycrystalline material is greater than or equal to 0.1 μm and less than or equal to 1.5 μm, optionally greater than 0.3 μm and less than or equal to 1.5 μm, more optionally greater than or equal to 0.4 μm and less than or equal to 1 μm, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, and a range consisting of any of the above-mentioned values. Thereby, during the battery charging and discharging cycle, the degree of material volume change can be slowed down, the degree of particle breakage can be reduced, and thus the cycle stability of the battery can be improved.

[0075] In some embodiments, the particle size of the primary particles is tested by Sigma 300 scanning electron microscope according to the method in JY / T 010-1996.

[0076] In some embodiments, the specific surface area of the positive electrode active material is 0.2-2 m 2 / g; and / or, the tap density of the positive electrode active material is 1.5-2.5 g / cm 3 .

[0077] In some embodiments, the specific surface area of the positive electrode active material can be, for example, 0.2 m 2 / g, 0.5 m 2 / g, 0.8 m 2 / g, 1 m 2 / g, 1.2 m 2 / g, 1.5 m 2 / g, 1.7 m 2 / g, 1.9 m 2 / g, 2 m 2 / g, and a range consisting of any of the above-mentioned values.

[0078] In some embodiments, the tap density of the positive electrode active material can be, for example, 1.5 g / cm 3 , 1.7 g / cm 3 , 1.8 g / cm 3 , 2.0 g / cm 3 , 2.1 g / cm 3 , 2.2 g / cm 3 , 2.4 g / cm 3 , 2.5 g / cm 3 and any range consisting of any of the above values.

[0079] In some embodiments, the specific surface area of the positive electrode active material can be measured by BET method, for example, the specific surface area can be measured according to the amount of nitrogen absorption at liquid nitrogen temperature (77 K) using a BELSorp-mini II of BEL Japan Co.

[0080] In some embodiments, the tap density of the positive electrode active material can be measured by a general tap density measuring device, for example, the tap density can be measured by a Tap-2S of Logan Co.

[0081] In some embodiments, the interlayer distance of the positive electrode active material is 0.45-0.50 nm.

[0082] [Method for preparing positive electrode active material]

[0083] One embodiment of the present application provides a method for preparing a positive electrode active material, comprising the following steps:

[0084] providing a solution containing a nickel source, the solution can also optionally contain a source of M1 element and / or a source of M2 element;

[0085] reacting the solution with an alkali solution to obtain a precipitate;

[0086] mixing the precipitate with a lithium source and a niobium source, and calcining to obtain the positive electrode active material;

[0087] wherein the positive electrode active material comprises (1-a)LiNi x M1 y M2 (1-x-y-z) Nb z O2·aLi2MnO3, wherein M1, M2, a, x, y and z are defined as described above.

[0088] Therefore, the application can improve the particle breakage of the lithium-rich manganese-based positive electrode material, stabilize the crystal structure of the material, improve the cycle stability of the battery, thereby inhibiting the capacity attenuation of the battery after cycling and improving the capacity of the battery after cycling by doping the lithium-rich manganese-based positive electrode material with an appropriate amount of Nb element and optionally doping M1 element and M2 element. Moreover, the application further improves the battery capacity by increasing the content of Ni element. Moreover, the method of the application is simple, efficient and safe, and has strong operability and adaptability, and is convenient for large-scale production.

[0089] In any embodiment, the molar ratio of the nickel element in the solution to the niobium element in the niobium source is 4-14, optionally 6-10, for example, can be 4, 4.5, 5, 5.5, 6, 6.4, 7, 7.6, 8, 8.4, 9, 9.6, 10, 10.5, 11, 11.4, 12, 12.3, 13, 13.5, 14 and any range consisting of the aforementioned values.

[0090] In some embodiments, the content of the nickel element in the solution is 0.1-1 mol / L, optionally 0.2-0.8 mol / L, for example, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, 0.65 mol / L, 0.7 mol / L, 0.75 mol / L, 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, 0.95 mol / L and any range consisting of the aforementioned values; and / or,

[0091] The content of the M1 element in the solution is 0-0.9 mol / L, optionally 0-0.7 mol / L, for example, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.56 mol / L, 0.6 mol / L, 0.67 mol / L, 0.7 mol / L, 0.75 mol / L, 0.8 mol / L and any range consisting of the aforementioned values; and / or,

[0092] The content of the M2 element in the solution is 0-0.3 mol / L, which can be selected as 0-0.1 mol / L, for example, 0.005 mol / L, 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.1 mol / L, 0.13 mol / L, 0.14 mol / L, 0.16 mol / L, 0.2 mol / L, 0.22 mol / L, 0.25 mol / L, 0.27 mol / L, 0.28 mol / L, and a range composed of any of the above values.

[0093] In some embodiments, the molar ratio of lithium element in the lithium source to niobium element in the niobium source is 7-32, which can be selected as 10-22, for example, 7, 8, 9, 10, 11, 13, 15, 16, 18, 20, 21, 22, 24, 25, 26, 28, 29, 30, 31, 32, and a range composed of any of the above values.

[0094] In some embodiments, the alkali solution includes sodium hydroxide and / or NH3·H2O; and / or,

[0095] The temperature of the calcination is 700-800°C, for example, 700°C, 720°C, 750°C, 780°C, 800°C, and a range composed of any of the above values; and / or,

[0096] The time of the calcination is 4-15 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 12 hours, 13 hours, 14 hours, 15 hours, and a range composed of any of the above values.

[0097] In some embodiments, the nickel source, the source of the M1 element, the source of the M2 element, the lithium source, and the niobium source each independently includes, but is not limited to, a nitrate salt, a chloride salt, a sulfate salt, a nitrite salt, a sulfite salt, a hydroxide, an oxide.

[0098] In some embodiments, the ratio of the molar amount of sodium hydroxide in the alkali solution to the total molar amount of the nickel source, the source of the M1 element, and the source of the M2 element in the solution is 0.95:1-20:1, for example, 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1, 19:1, and a range composed of any of the above values.

[0099] In some embodiments, the ratio of the molar amount of ammonia (calculated as NH3H2O) in the alkaline solution to the total molar amount of the source of nickel, the source of the M1 element, and the source of the M2 element in the solution is 0.56:1 to 11.8:1, for example, 0.7:1, 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, 11:1, and any range of values formed from any of the above-mentioned values.

[0100] In some embodiments, the volume ratio of the solution to the alkaline solution is 1:1 to 2:1, for example, 1.2:1, 1.6:1, 1.8:1, 2:1, and any range of values formed from any of the above-mentioned values.

[0101] [Positive electrode tab]

[0102] The positive electrode tab generally includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including the positive electrode active material described above or the positive electrode active material prepared by the method described above.

[0103] As an example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two surfaces of the positive electrode current collector.

[0104] In some embodiments, the positive electrode current collector can employ a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0105] In some embodiments, the positive electrode film layer can further optionally include a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic ester resin.

[0106] In some embodiments, the positive electrode film layer can further optionally include a conductive agent. As an example, the conductive agent can include at least one of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0107] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector; and subjecting the same to drying, cold pressing, and the like to obtain the positive electrode sheet.

[0108] [Positive electrode sheet]

[0109] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0110] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two surfaces of the negative electrode current collector.

[0111] In some embodiments, the negative electrode current collector can employ a metal foil or a composite current collector. As a metal foil, for example, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer such as a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0112] In some embodiments, the negative electrode active material can employ a negative electrode active material for a battery known in the art. As an example, the negative electrode active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material for a battery can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0113] In some embodiments, the negative electrode film layer can also optionally include a binder. As an example, the binder can be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0114] In some embodiments, the negative electrode film layer can also optionally include a conductive agent. As an example, the conductive agent can be selected from at least one of super-P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0115] In some embodiments, the negative electrode film layer can also optionally include other additives, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)), etc.

[0116] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry on a negative electrode current collector, and after processes such as drying, cold pressing, etc., the negative electrode sheet can be obtained.

[0117] [Electrolyte]

[0118] The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The type of electrolyte is not specifically limited in the present application and can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0119] In some embodiments, the electrolyte is liquid and includes an electrolyte salt and a solvent.

[0120] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro oxalate borate, lithium di oxalate borate, lithium difluoro di oxalate phosphate, and lithium tetrafluoro oxalate phosphate.

[0121] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0122] In some embodiments, the electrolyte can also optionally include an additive. As an example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive capable of improving certain properties of the battery, such as an additive for improving overcharge performance of the battery, an additive for improving high-temperature or low-temperature performance of the battery, etc.

[0123] [Separator]

[0124] In some embodiments, the secondary battery further comprises a separator. The type of the separator is not particularly limited in the present application, and any known porous separator having good chemical stability and mechanical stability can be used.

[0125] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0126] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be used to form an electrode assembly by a winding process or a stacking process.

[0127] In some embodiments, the secondary battery can comprise an outer package. The outer package can be used to package the electrode assembly and the electrolyte described above.

[0128] In some embodiments, the outer package of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and as the plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate, etc. can be listed.

[0129] The shape of the secondary battery is not particularly limited in the present application, and it can be cylindrical, square, or any other shape. For example, Figure 1 is a square structure secondary battery 5 as an example.

[0130] In some embodiments, referring to Figure 2 , the outer package can comprise a shell 51 and a cover plate 53. The shell 51 can comprise a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be arranged on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can be used to form an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and the person skilled in the art can select according to the specific actual needs.

[0131] In some embodiments, the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by the person skilled in the art according to the application and capacity of the battery module.

[0132] Figure 3 is a battery module 4 as an example. Referring to Figure 3In the battery module 4, the plurality of secondary batteries 5 can be arranged in series along the length direction of the battery module 4. Of course, the plurality of secondary batteries 5 can be arranged in any other manner. The plurality of secondary batteries 5 can be further fixed by fasteners.

[0133] Optionally, the battery module 4 can further include a housing having an accommodation space, and the plurality of secondary batteries 5 can be accommodated in the accommodation space.

[0134] In some embodiments, the above-described battery module can be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0135] Figure 4 And Figure 5 is a battery pack 1 as an example. Referring to Figure 4 And Figure 5 In the battery pack 1, a battery box and a plurality of battery modules 4 arranged in the battery box can be included. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be arranged on the lower box body 3 and form a closed space for accommodating the battery module 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0136] In this application, the battery can include but is not limited to the above-mentioned secondary battery, battery module and battery pack.

[0137] In addition, the present application also provides a power utilization device, which includes at least one of the secondary battery, the battery module, or the battery pack provided by the present application. The secondary battery, the battery module, or the battery pack can be used as a power supply of the power utilization device, or can be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0138] As the power utilization device, the secondary battery, the battery module or the battery pack can be selected according to the use requirements thereof.

[0139] Figure 6 is a power utilization device as an example. The power utilization device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the secondary battery for the power utilization device, the battery pack or the battery module can be used.

[0140] [Embodiment]

[0141] Hereinafter, the examples of the present application will be described. The examples described below are illustrative and are intended to be purely exemplary of the application and are not intended to limit the application. Unless otherwise indicated, technical or conditions not specified in the examples are performed according to the techniques or conditions described in the literature in the art or according to the product manual. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained commercially.

[0142] Example 1

[0143] 1. Preparation of the positive electrode active material: 0.235 mol of manganese nitrate, 0.045 mol of cobalt nitrate and 0.63 mol of nickel nitrate were dissolved in 1000 ml of deionized water to obtain a solution; 500 mL of 4M NaOH aqueous solution and 116 mL of 10.2M NH3·H2O aqueous solution were added to the solution, and stirring was performed to obtain a precipitate, which was filtered and collected, and dried at 110°C to constant weight to obtain a precursor material. The entire precursor material was mixed uniformly with 1.1 mol of LiOH and 0.045 mol of Nb2O5, and calcined at 750°C for 9h to obtain a Nb-doped high-nickel lithium-rich positive electrode active material 0.9LiNi0.8Co0.1Mn0.1O2·0.1Li2MnO3. 0.7 Mn 0.15 Co 0.05 Nb 0.1 O2·0.1Li2MnO3.

[0144] 2. Preparation of the positive electrode tab: the positive electrode active material, the conductive agent acetylene black and the binder PVDF (polyvinylidene fluoride) were mixed in a mass ratio of 8:1:1 with N-methyl pyrrolidone NMP as the solvent to prepare a slurry, which was coated on an aluminum foil, dried at 80°C for 12 hours, rolled and punched into a circular tab with a diameter of 10 mm as the positive electrode tab.

[0145] 3. Negative electrode tab: lithium metal tab.

[0146] 4. Separating membrane: PE separating membrane was used.

[0147] 5. Preparation of the electrolyte: ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed in a volume ratio of 1:1, and then LiPF6 was uniformly dissolved in the above solution to obtain an electrolyte. In the electrolyte, the concentration of LiPF6 was 1 mol / L.

[0148] 6. Preparation of the battery: the above positive electrode tab, the separating membrane, the negative electrode tab and the electrolyte were assembled into a CR2032 type button cell.

[0149] Examples 2-20 and Comparative Examples 1-5 were prepared in a similar manner to the secondary battery preparation method of Example 1, but the preparation method of the positive electrode active material and the product parameters were different. The differences between the preparation method of the positive electrode active material of Examples 2-20 and Comparative Examples 1-5 and Example 1 are shown in Table 1, and the differences between the product parameters of Examples 2-20 and Comparative Examples 1-5 and Example 1 are shown in Table 2.

[0150] The preparation method of the positive electrode active material of Example 15 is the same as that of Example 13 except that 500 mL of 4M NaOH aqueous solution is changed to 450 mL, and the calcination process is changed to calcination at 800°C for 10h.

[0151] The preparation method of the positive electrode active material of Example 16 is the same as that of Example 11 except that 500 mL of 4M NaOH aqueous solution is changed to 400 mL, and the calcination process is changed to calcination at 800°C for 10h.

[0152]

[0153]

[0154]

[0155] Test Example

[0156] (1) Test of primary particle size: The test was performed according to the method in JY / T010-1996 using a Sigma 300 scanning electron microscope.

[0157] (2) Test of 0.5C battery capacity: The battery was tested on a new battery test system at room temperature, and constant current charge and discharge were performed three times at a current density of 0.5C, the voltage range of charge and discharge was 2.5-4.8V, and the discharge capacity value of the third time was taken as the 0.5C battery capacity.

[0158] (3) Test of battery capacity after 0.5C 100 cycles: The cycle charge and discharge was continued according to the method in the above item (3) until 100 cycles, and the discharge capacity of the 100th cycle was taken as the battery capacity after 0.5C 100 cycles.

[0159] (4) Test of cycle performance: According to the results of items (3) and (4), the cycle capacity retention rate of 0.5C 100 cycles was calculated according to the following formula:

[0160]

[0161] The results of item (1) are shown in Table 2, and the results of items (2)-(4) are shown in Tables 3-4.

[0162] Table 3: Test results of battery capacity after 0.5C 100 cycles of Examples 1-20 and Comparative Examples 1-5

[0163]

[0164]

[0165] As shown in Table 3, compared with Comparative Examples 1-5, the battery capacity of the battery after 0.5C 100 cycles of the battery of the present application is significantly higher.

[0166] Table 4: Test results of cycle capacity retention rate, 0.5C battery capacity and battery capacity after 0.5C 100 cycles of Examples 1-20

[0167]

[0168]

[0169] As shown in Table 4:

[0170] Compared with Example 4, the cycle capacity retention rate, 0.5C battery capacity and battery capacity after 0.5C 100 cycles of Examples 1-3, 6 and 8 are significantly improved; compared with Example 5, the cycle capacity retention rate and battery capacity after 0.5C 100 cycles of Examples 1-3, 6 and 8 are significantly improved;

[0171] Compared with Examples 7, 12, 14 and 19, the 0.5C battery capacity and battery capacity after 0.5C 100 cycles of Examples 1-3, 6 and 8 are significantly improved;

[0172] Compared with Examples 13, 15 and 16, the cycle capacity retention rate, 0.5C battery capacity and battery capacity after 0.5C 100 cycles of Examples 1-3, 6 and 8 are significantly improved; compared with Example 11, the 0.5C battery capacity and battery capacity after 0.5C 100 cycles of Examples 1-3, 6 and 8 are significantly improved;

[0173] Compared with Example 10, the cycle capacity retention rate, 0.5C battery capacity and battery capacity after 0.5C 100 cycles of Examples 1-3, 6 and 8 are significantly improved; compared with Example 9, the 0.5C battery capacity and battery capacity after 0.5C 100 cycles of Examples 1-3, 6 and 8 are significantly improved.

[0174] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration, function, and effect as the technical idea of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications to the embodiments, or by combining part of the configurations of the embodiments, which can be conceived by those skilled in the art, without departing from the spirit of the present application, are also included in the scope of the present application.

Claims

1. A positive electrode active material comprising (1-a)LiNi x M1 y M2 (1-x-y-z) Nb z O2·aLi2MnO3; where, The M1 includes one or two elements of Mn and Al; The M2 includes one or more of transition metal elements other than Mn element, Ni element and Nb element; 0 < a < 1; 0.6 ≤ x < 1, 0 ≤ y < 0.4, 0.1 < z ≤ 0.15, and 0.6 < x + y + z ≤ 1, 4 ≤ x / z ≤ 14, The volume average particle size Dv50 of the positive electrode active material is 1 - 10 µm.

2. The positive electrode active material according to claim 1, wherein, 6 ≤ x / z ≤ 10.

3. The positive electrode active material according to claim 1 or 2, wherein, 0.7≤x≤0.85。 4. The positive electrode active material according to claim 1 or 2, wherein, 0.05≤a≤0.6。 5. The positive electrode active material according to claim 1 or 2, wherein, 0.1≤a≤0.5。 6. The positive electrode active material according to claim 1 or 2, wherein, The M2 includes one or more of Co, Mo and Zr.

7. The positive electrode active material according to claim 6, wherein, The M2 includes Co element.

8. The positive electrode active material according to claim 1 or 2, wherein, The positive electrode active material includes a polycrystalline material, and the particle size of the primary particles of the polycrystalline material is greater than or equal to 0.1 µm and less than or equal to 1.5 µm.

9. The positive electrode active material according to claim 8, wherein, The positive electrode active material includes a polycrystalline material, and the particle size of the primary particles of the polycrystalline material is greater than 0.3 µm and less than or equal to 1.5 µm.

10. The positive electrode active material according to claim 8, wherein, The positive electrode active material includes a polycrystalline material, and the particle size of the primary particles of the polycrystalline material is greater than or equal to 0.4 µm and less than or equal to 1 µm.

11. The positive electrode active material according to claim 1 or claim 2, wherein, The specific surface area of ​​the positive electrode active material is 0.2-2 m². 2 / g; and / or, The tap density of the positive electrode active material is 1.5-2.5 g / cm³. 3 .

12. A method for preparing the positive electrode active material according to any one of claims 1 to 11, comprising the following steps: Providing a solution containing a nickel source, and the solution may also optionally contain a source of M1 element and / or a source of M2 element; Reacting the solution with an alkali solution to obtain a precipitate; Mixing the precipitate with a lithium source and a niobium source, and roasting to obtain a positive electrode active material; the molar ratio of nickel element in the solution to niobium element in the niobium source is 4 - 14.

13. The preparation method according to claim 12, wherein, The molar ratio of nickel element in the solution to niobium element in the niobium source is 6 - 10.

14. The preparation method according to claim 12 or 13, wherein, In the solution, the content of nickel element is 0.1 - 1 mol / L; and / or, In the solution, the content of M1 element is 0 - 0.9 mol / L; and / or, In the solution, the content of M2 element is 0 - 0.3 mol / L.

15. The preparation method according to claim 14, wherein, In the solution, the content of nickel element is 0.2 - 0.8 mol / L; and / or, In the solution, the content of M1 element is 0 - 0.7 mol / L; and / or, In the solution, the content of M2 element is 0 - 0.1 mol / L.

16. The preparation method according to claim 12 or 13, wherein, The molar ratio of lithium element in the lithium source to niobium element in the niobium source is 7 - 32.

17. The preparation method according to claim 16, wherein, The molar ratio of lithium element in the lithium source to niobium element in the niobium source is 10 - 22.

18. The preparation method according to claim 12 or 13, wherein, The alkali solution includes sodium hydroxide and / or NH3·H2O; and / or, The roasting temperature is 700 °C - 800 °C; and / or, The roasting time is 4 - 15 hours.

19. A positive electrode sheet, comprising the positive electrode active material according to any one of claims 1 to 11 or the positive electrode active material prepared by the method according to any one of claims 12 to 18.

20. A battery, comprising the positive electrode active material according to any one of claims 1 to 11, the positive electrode active material prepared by the method according to any one of claims 12 to 18 or the positive electrode sheet according to claim 19.

21. An electrical device comprising the battery of claim 20.

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