Positive electrode active material and its manufacturing method, positive electrode plate, battery and power consumption device

Abstract

The present application discloses a positive electrode active material and a method for producing the same, a positive electrode plate, a battery and a power consuming device, and the positive electrode active material is Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f wherein M1 comprises a rare earth element, M2 comprises at least one of a Group IA element, a Group IIA element, a Group IIIA element, a Group IVA element, a Group VA element, a Group VIA element, and a transition element, and 0.6≦x≦1.2, 0

Description

[Technical Field]

[0001] The present application relates to the technical field of secondary batteries, and more particularly to a positive electrode active material and a method for producing the same, a positive electrode plate, a battery, and a power consuming device. [Background technology]

[0002] Secondary batteries are not only applied to energy storage power systems such as hydroelectric, thermal, wind and solar power plants, but also widely used in multiple fields such as electric transportation such as electric bicycles, electric motorcycles and electric cars, as well as military equipment and aerospace.

[0003] Sodium-ion batteries are a type of secondary battery, and layered transition metal oxides are commonly used as cathode active materials for sodium-ion batteries. However, the capacity retention rate of sodium-ion batteries containing conventional layered transition metal oxides is relatively low. Summary of the Invention [Problem to be solved by the invention]

[0004] In view of the technical problems existing in the background art, the present application aims to provide a positive electrode active material and to solve the problem of low capacity retention rate of a battery containing the same. [Means for solving the problem]

[0005] In order to achieve the above object, a first aspect of the present application provides a positive electrode active material, the positive electrode active material comprising: Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f Including, wherein M1 includes a rare earth element, M2 includes at least one of a group IA element, a group IIA element, a group IIIA element, a group IVA element, a group VA element, a group VIA element, and a transition element, and 0.6≦x≦1.2, 0 <a≦0.5、0<b≦0.4、0.3≦c≦0.75、0.001≦d≦0.05、0≦e≦0.3、-0.1≦δ≦0.1、0≦f≦0.1、0.005≦d / c≦0.05、a+b+c+d+e=1である。

[0006] The present application has at least the following beneficial effects: The main body material of the positive electrode active material of the present application comprises NiFeMn and is doped with a rare earth element M1 and a doping element M2. The above-mentioned content of Fe can improve the specific capacity of the material. The rare earth element M1 has a large radius, forming a dense and uniform doping layer on the surface of the positive electrode active material. The doping layer effectively prevents water vapor from penetrating from the surface of the positive electrode active material into the bulk phase, improving the structural stability of the material. During high-voltage charging, the doping layer further inhibits the precipitation of lattice oxygen and the penetration of electrolyte into the material, improving the structural stability of the material and thereby improving the capacity retention of batteries containing it. The doping element M2 is distributed in the bulk phase of the positive electrode active material and forms strong chemical bonds with O in the positive electrode active material, inhibiting the detachment of Na ions from the bulk phase of the positive electrode active material and reducing changes in the layer spacing of the positive electrode active material, delaying the occurrence of phase change, improving the cycle stability of the positive electrode active material, and thereby improving the capacity retention of batteries. In addition, the ratio d / c of ​​the rare earth element M1 to Mn in the positive electrode active material being within the above range is advantageous in improving the air stability and cycle stability of the positive electrode active material, thereby improving the capacity retention rate of a battery containing it.

[0007] In some embodiments of the present application, the rare earth element includes at least one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. This allows M1 to form a dense and uniform doping layer on the surface of the positive electrode active material using at least one of the rare earth elements, reducing the probability of a phase change occurring in the positive electrode active material and improving the cycle performance of the positive electrode active material, thereby improving the capacity retention rate of a battery containing the positive electrode active material.

[0008] In some embodiments of the present application, the M2 includes at least one of B, Mg, Al, Si, K, Ca, Ga, Ge, Se, Rb, Sr, In, Sn, Sb, Te, Sc, Ti, V, Cr, Co, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, and Au. This allows the element M2 to be uniformly distributed in the bulk phase of the positive electrode active material, form strong chemical bonds with O in the positive electrode active material, suppress detachment of Na from the bulk phase in the positive electrode active material, improve the air stability of the positive electrode active material, and thereby improve the capacity retention rate of a battery containing the same.

[0009] In some embodiments of the present application, 0.01≦d / c≦0.03, which is advantageous for improving the air stability and cycle stability of the positive electrode active material, and thereby improving the capacity retention rate of a battery containing it.

[0010] In some embodiments of the present application, the positive electrode active material satisfies at least one of the following conditions: 0.1≦a≦0.4, and optionally 0.15≦a≦0.3; 0.1≦b≦0.35, and optionally 0.15≦b≦0.35; and 0.35≦c≦0.6, and optionally 0.35≦c≦0.5.

[0011] In some embodiments of the present application, 1.75 ≦ (a + b + c) / b ≦ 9.5, optionally 2 ≦ (a + b + c) / b ≦ 9.5, and further optionally 2 ≦ (a + b + c) / b ≦ 6.3. Thereby, in the positive electrode active material, the ratio of the sum of the contents of Ni, Fe, and Mn to the content of Fe is within the above range, which is advantageous for improving the air stability and cycle stability of the positive electrode active material, and thereby improving the capacity retention rate of the battery containing it.

[0012] In some embodiments of the present application, 0.8 < x ≦ 1.0, the phase state of the positive electrode active material includes the O3 phase, and the space group is TIFF2026508647000002.tif7168, and the layer spacing is between 0.53 nm and 0.55 nm. Thereby, x is within the above range, the Na content of the formed O3-phase positive electrode active material is high, and the capacity of the battery can be improved.

[0013] In some embodiments of the present application, 0.6 ≦ x ≦ 0.8, the phase state of the positive electrode active material includes the P2 phase, the space group includes P63 / mmc, and the layer spacing is between 0.54 nm and 0.57 nm. Thereby, x is within the above range, the layer spacing of the formed P2-phase positive electrode active material is large, and the rate performance and cycle performance of the battery can be improved.

[0014] In some embodiments of the present application, the pH value of the immersion solution of the positive electrode active material is 13 or less, optionally the pH value of the immersion solution of the positive electrode active material is 12.7 or less, and further optionally the pH value of the immersion solution of the positive electrode active material is 11.0 ≦ pH ≦ 12.7.

[0015] In some embodiments of the present application, the positive electrode active material is The D of the positive electrode active material v 50 is between 3 μm and 30 μm, optionally between 5 μm and 15 μm, and The specific surface area of the positive electrode active material is 0.1 m 2 / g - 5 m 2 / g, optionally 0.3 m 2 / g - 3 m2 / g, and The tap density of the positive electrode active material is 1 g / cm 3 -3g / cm 3 and selectively 1.5 g / cm 3 -2.5g / cm 3 and The positive electrode active material has a compaction density of 3.0 g / cm at a pressure of 300 MPa. 3 -4.0g / cm 3 and satisfy at least one of the conditions:

[0016] This allows the positive electrode active material D v When at least one of the specific surface area, tap density, and compaction density at a pressure of 300 MPa is within the above range, the conduction distance of sodium ions within the positive electrode active material is short, the surface side reactions are reduced, the positive electrode active material is promoted to exert its gram capacity, and the capacity retention rate of a battery containing it is improved.

[0017] A second aspect of the present application provides a method for producing the positive electrode active material according to the first aspect, mixing a Na source, a Ni source, an Fe source, a Mn source, an M1 source, and an M2 source to obtain a precursor; and calcining the precursor to obtain a positive electrode active material.

[0018] As a result, the positive electrode active material prepared in the present application has excellent air stability and cycle stability, and the battery containing it has excellent capacity retention.

[0019] A third aspect of the present application provides another method for producing the cathode active material according to the first aspect, mixing a Ni source, an Fe source, a Mn source, an M1 source, and an M2 source with water to obtain a mixed solution; reacting the solution with a precipitating agent to obtain a precursor; and mixing the precursor with a Na source and then calcining the mixture to obtain a positive electrode active material.

[0020] As a result, the cathode active material prepared in the present application has excellent air stability and cycle stability, and a battery containing the cathode active material has excellent capacity retention.

[0021] A fourth aspect of the present application provides a positive electrode plate comprising the positive electrode active material according to the first aspect of the present application, the positive electrode active material produced by the method according to the second aspect, or the positive electrode active material produced by the method according to the third aspect.

[0022] A fifth aspect of the present application provides a battery including the positive electrode plate according to the fourth aspect of the present application, whereby the battery has an excellent capacity retention rate.

[0023] A sixth aspect of the present application provides a power consuming device including the battery according to the fifth aspect.

[0024] Additional aspects and advantages of the present application will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the present application. [Brief explanation of the drawings]

[0025] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments. The drawings are only used to illustrate the purpose of the preferred embodiments and are not to be considered as limitations on the present application. Note that the same drawing numbers refer to the same elements in all drawings. In the drawings, [Figure 1] 1 is a structural schematic diagram of a battery according to an embodiment of the present application; [Figure 2] 1 is a structural schematic diagram of a battery module according to an embodiment of the present application; [Figure 3] 1 is a structural schematic diagram of a battery pack according to an embodiment of the present application; [Figure 4] FIG. 4 is an exploded view of FIG. 3. [Figure 5] FIG. 1 is a schematic diagram of an embodiment of a power consuming device that uses a battery as a power source. [Figure 6] FIG. 2 is an XRD diagram of the positive electrode active materials of Example 1 and Comparative Example 1 of the present application. [Figure 7] FIG. 2 is an XRD diagram of the positive electrode active materials of Example 1 and Comparative Example 2 of the present application. [Figure 8] FIG. 2 is a charge and discharge diagram of the positive electrode plate of Example 1 of the present application at 1.5-4.2 / 4.2-1.5V. [Figure 9] FIG. 2 is a comparison diagram of the capacity retention rates of the batteries of Example 1 and Comparative Example 4 of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0026] The following detailed description will be given of examples of the technical solution of the present application. The following examples are merely for the purpose of more clearly illustrating the technical solution of the present application, and are for illustrative purposes only and should not be used to limit the scope of protection of the present application.

[0027] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. Appearances of this phrase in various locations throughout the specification do not necessarily all refer to the same embodiment, nor are they mutually exclusive, independent, or alternative embodiments. Those skilled in the art can explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0028] For clarity, this specification specifically discloses only some numerical ranges. However, any lower limit and any upper limit can be combined to form a range not expressly stated, and any lower limit and any other lower limit can be combined to form a range not expressly stated, and similarly, any upper limit and any other upper limit can be combined to form a range not expressly stated. Furthermore, each point or single numerical value disclosed alone may itself be combined as a lower limit or upper limit with any other point or single numerical value, or with other lower limits or upper limits, to form a range not expressly stated.

[0029] In the description of the embodiments of this application, the term "and / or" is merely a relation that describes related objects and indicates that three relations may exist. For example, A and / or B may represent three cases: A alone, a combination of A and B, and B alone. In addition, the character " / " in this specification generally indicates that the related objects before and after are in an "or" relationship.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art of this application, and the terms used herein are only for describing specific embodiments and are not intended to limit this application. The terms "comprises" and "having" and any variations thereof in the specification and claims of this application and the description of the drawings above are intended to cover a non-exclusive "comprise."

[0031] With the development of electric vehicle and rechargeable mobile device technologies and the increasing demand, secondary batteries, as a representative of the new energy field, are also experiencing rapid development in related research. Sodium-ion batteries have a strong price advantage over conventional lithium-ion batteries and have the potential for wide application in large-scale energy storage systems.

[0032] Layered transition metal oxides have become one of the popular sodium-ion battery cathode active materials due to their high electrical conductivity, high energy density, relatively large capacity, and relatively long cycle life.

[0033] However, conventional layered transition metal oxides have the following problems: First, water vapor in the air penetrates the layered transition metal oxide's surface into the bulk phase, making the layered transition metal oxide susceptible to structural destruction after prolonged exposure to air; second, during high-voltage charging, the oxygen coordinated to the metal in the layered transition metal oxide also undergoes an oxidation reaction, i.e., lattice oxygen release occurs, causing structural destruction; and third, during high-voltage charging, cracks form in the layered transition metal oxide due to a phase change associated with the release of sodium ions, allowing the electrolyte to penetrate through the cracks and react with the interior of the material, deteriorating the material's structure. Destruction of the layered transition metal oxide material structure reduces the stability of the material, which directly leads to a decrease in the battery's capacity retention rate.

[0034] In the present application, the positive electrode active material is made of NiFeMn as a main body material and doped with a rare earth element M1 and a doping element M2, with the ratio of the rare earth element M1 to Mn being controlled. On the one hand, the rare earth element M1 has a large radius and remains on the surface of the positive electrode active material, forming a dense and uniform doping layer on the surface of the positive electrode active material. The doping layer effectively prevents water vapor from penetrating from the surface to the bulk phase of the positive electrode active material, improving the structural stability of the material. Furthermore, during high-voltage charging, the doping layer further inhibits lattice oxygen precipitation and electrolyte penetration into the material, improving the structural stability of the material and thereby improving the capacity retention of batteries containing the positive electrode active material. On the other hand, the doping element M2 is distributed in the bulk phase of the positive electrode active material and forms strong chemical bonds with O in the positive electrode active material, inhibiting the desorption of Na ions from the bulk phase of the positive electrode active material and reducing the change in the layer spacing of the positive electrode active material, delaying the occurrence of phase change, and improving the cycling stability of the positive electrode active material. In addition, in the present application, by controlling the ratio d / c of ​​the rare earth element M1 to Mn in the positive electrode active material to 0.005-0.05, it is advantageous to improve the air stability and cycle stability of the positive electrode active material, thereby improving the capacity retention rate of the battery containing it.

[0035] The positive electrode active materials disclosed in the examples of the present application can be applied to secondary batteries, and the batteries disclosed in the examples of the present application can be used in power-consuming devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. Power-consuming devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, battery-powered vehicles, electric vehicles, ships, spacecraft, etc. Here, electric toys may include stationary or mobile electric toys, such as game consoles, electric car toys, electric steamship toys, and electric airplane toys, and spacecraft may include airplanes, rockets, spacecraft, and spaceships.

[0036] A first aspect of the present application provides a positive electrode active material, the positive electrode active material comprising: Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f Including, wherein M1 includes a rare earth element, M2 includes at least one of a group IA element, a group IIA element, a group IIIA element, a group IVA element, a group VA element, a group VIA element, and a transition element, and 0.6≦x≦1.2, 0 <a≦0.5、0<b≦0.4、0.3≦c≦0.75、0.001≦d≦0.05、0≦e≦0.3、-0.1≦δ≦0.1、0≦f≦0.1、0.005≦d / c≦0.05、a+b+c+d+e=1である。

[0037] The present application has at least the following beneficial effects: the main body material in the present application comprises NiFeMn and is doped with a rare earth element M1 and a doping element M2, and the above-mentioned content of Fe can improve the specific capacity of the positive electrode active material; the rare earth element M1 has a large radius, forming a dense and uniform doping layer on the surface of the positive electrode active material. The doping layer can effectively prevent water vapor from penetrating from the surface of the positive electrode active material into the bulk phase, improving the structural stability of the material; and during high-voltage charging, the doping layer can further inhibit lattice oxygen precipitation and electrolyte penetration into the material, improving the structural stability of the material and thereby improving the capacity retention rate of batteries containing it. The doping element M2 is distributed in the bulk phase of the positive electrode active material and forms strong chemical bonds with O in the positive electrode active material, which can inhibit the detachment of Na ions from the bulk phase in the positive electrode active material, reduce changes in the layer spacing of the positive electrode active material, delay the occurrence of phase changes, and improve the cycle stability of the positive electrode active material, thereby improving the capacity retention rate of the battery.

[0038] In addition, having the ratio d / c of ​​the rare earth element M1 to Mn in the positive electrode active material within the above range can reduce the formation of a heterophase due to insufficient solid solubility between the rare earth element and Mn, which causes the rare earth element to aggregate on the surface of the positive electrode active material. At the same time, it reduces the probability that a rare earth doped layer cannot be formed due to a lack of rare earth element, which is advantageous for the rare earth element to form a dense and uniform rare earth doped layer on the surface of the positive electrode active material. It also effectively blocks the intrusion of water vapor from the surface of the positive electrode active material into the bulk phase, suppresses the precipitation of lattice oxygen and the penetration of the electrolyte into the bulk phase, improves the air stability and cycle stability of the positive electrode active material, and thereby improves the capacity retention rate of batteries containing it.

[0039] In summary, the main body material of the positive electrode active material includes NiFeMn, and is doped with a rare earth element M1 and a doping element M2. The doping amount and d / c of ​​each element are controlled, and the above conditions work together to improve the specific capacity of the positive electrode active material.

[0040] In some embodiments of the present application, in the above positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f x may take values such as 0.6 ≤ x ≤ 1.2, for example 0.7 ≤ x ≤ 1.1, 0.8 ≤ x ≤ 1, 0.9 ≤ x ≤ 1.1, 1 ≤ x ≤ 1.1, etc. Thereby, this positive electrode active material contains sodium elements with this content, giving the battery a relatively high capacity. <00OO383>

[0041] It should be noted that in the positive electrode plate, battery or power consumption device, during processes such as formation and cycling, sodium ions are consumed, so a situation may occur where the measured content x of sodium elements in the positive electrode active material is less than 1. At the same time, when the positive electrode plate and the negative electrode plate use a sodium replenisher, after processes such as formation and cycling, a situation may occur where the measured content x of sodium elements in the positive electrode active material is greater than 1.

[0042] In some embodiments of the present application, in the above positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f a may take values such as 0 < a ≤ 0.5, for example 0.001 ≤ a ≤ 0.5, 0.005 ≤ a ≤ 0.5, 0.1 ≤ a ≤ 0.5, 0.15 ≤ a ≤ 0.45, 0.2 ≤ a ≤ 0.4, 0.25 ≤ a ≤ 0.35, 0.25 ≤ a ≤ 0.3, etc. Thereby, this positive electrode active material contains nickel with this content, and the energy density of the battery can be improved. In some other embodiments of the present application, in the above positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F fIn this case, a may take a value such that 0.1 ≤ a ≤ 0.4, for example, 0.15 ≤ a ≤ 0.3.

[0043] In some embodiments of the present application, the above positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f In this case, b may take a value such that 0 < b ≤ 0.4, for example, 0.001 ≤ a ≤ 0.4, 0.005 ≤ a ≤ 0.4, 0.1 ≤ a ≤ 0.4, 0.15 ≤ a ≤ 0.35, 0.2 ≤ a ≤ 0.35, 0.25 ≤ a ≤ 0.35, 0.3 ≤ a ≤ 0.35, etc. Thereby, in the process of Na ions desorbing from the material, Fe is oxidized from the trivalent state to the tetravalent state as a charge compensation metal element. When Na ions are re-inserted into the material, Fe is reduced from the tetravalent state to the trivalent state. This positive electrode active material contains Fe with this content, and the specific capacity of the material can be improved. In some other embodiments of the present application, the above positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f In this case, b may take a value such that 0.1 ≤ b ≤ 0.35, for example, 0.15 ≤ b ≤ 0.35.

[0044] In some embodiments of the present application, the above positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F fIn the formula, c may be 0.3≦c≦0.75, for example, 0.35≦c≦0.75, 0.4≦c≦0.7, 0.45≦c≦0.65, 0.5≦c≦0.6, 0.55≦c≦0.6, etc. As a result, Mn at this content dissolves in solid solution with the rare earth element M1 to form a uniform and dense doping layer on the surface of the positive electrode active material, improving the structural stability of the positive electrode active material and thereby improving the capacity retention rate of a battery containing it. In some other embodiments of the present application, the positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f In the above formula, c may be 0.35≦c≦0.6, for example, 0.35≦c≦0.5.

[0045] In some embodiments of the present application, the positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f In the present invention, M1 includes at least one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. This allows M1 to form a dense, uniform doping layer on the surface of the positive electrode active material, effectively preventing water vapor from penetrating from the surface to the bulk phase of the positive electrode active material and improving the structural stability of the material. At the same time, during high-voltage charging, this doping layer further inhibits lattice oxygen precipitation and electrolyte penetration into the material, improving the structural stability of the material and thereby improving the capacity retention of batteries containing it.

[0046] Furthermore, M1 uses at least one of the above elements, making it environmentally friendly and less polluting.

[0047] In some embodiments of the present application, the positive electrode active material Na x Ni a Feb Mn c M1 d M2 e O 2+δ-f F f where d is 0.001≦d≦0.05, such as 0.005≦d≦0.05, 0.01≦d≦0.05, 0.015≦d≦0.045, 0.02≦d≦0.04, 0.025≦d≦0.035, or 0.03≦d≦0.035, whereby this positive electrode active material contains this amount of M1 element, forming a dense and uniform doping layer on the surface of the positive electrode active material, effectively preventing water vapor from penetrating from the surface to the bulk phase of the positive electrode active material and improving the structural stability of the material. At the same time, during high-voltage charging, this doping layer further inhibits lattice oxygen precipitation and electrolyte penetration into the material, improving the structural stability of the material and thereby improving the capacity retention rate of batteries containing it.

[0048] In some embodiments of the present application, the positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F fThe contents of the rare earth element M1 and Mn satisfy the relational expression 0.005≦d / c≦0.05, for example, 0.01≦d / c≦0.05, 0.015≦d / c≦0.045, 0.02≦d / c≦0.04, 0.025≦d / c≦0.035, 0.03≦d / c≦0.035. The ratio d / c of ​​the rare earth element M1 to Mn in the positive electrode active material within the above range can reduce the formation of a heterophase due to the aggregation of the rare earth element on the surface of the positive electrode active material caused by insufficient solid solubility between the rare earth element and Mn, and simultaneously reduce the probability of a rare earth element insufficiency causing a rare earth doped layer to be unable to be formed, which is advantageous for the rare earth element to form a dense and uniform rare earth doped layer on the surface of the positive electrode active material, effectively blocking the penetration of water vapor from the surface of the positive electrode active material into the bulk phase, suppressing the precipitation of lattice oxygen and the penetration of the electrolyte into the bulk phase, improving the air stability and cycle stability of the positive electrode active material, and thereby improving the capacity retention rate of a battery containing it. In some other embodiments of the present application, the positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f The contents of the rare earth element M1 and Mn in the positive electrode active material satisfy the following relational expression: 0.01≦d / c≦0.03, which is advantageous in improving the air stability and cycle stability of the positive electrode active material, and thereby improving the capacity retention rate of the battery containing the positive electrode active material.

[0049] In some embodiments of the present application, the positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F fIn the positive electrode active material, M2 includes at least one of B, Mg, Al, Si, K, Ca, Ga, Ge, Se, Rb, Sr, In, Sn, Sb, Te, Sc, Ti, V, Cr, Co, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, and Au. Specifically, in the positive electrode active material, the element M2 is uniformly distributed in the bulk phase thereof, and M2 can form a strong chemical bond with O in the positive electrode active material. This chemical bond, on the one hand, inhibits the detachment of Na from the bulk phase in the positive electrode active material, and on the other hand, stabilizes the structure of the metal layer of the positive electrode active material, reduces changes in the layer spacing of the positive electrode active material, reduces the occurrence of phase changes, improves the cycle performance of the positive electrode active material, and thereby improves the capacity retention rate of batteries containing it.

[0050] In some embodiments, the positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f where δ and f satisfy -0.1≦δ≦0.1 and 0≦f≦0.1, such as -0.09≦δ≦0.09, -0.08≦δ≦0.08, -0.07≦δ≦0.07, -0.06≦δ≦0.06, -0.05≦δ≦0.05, -0.04≦δ≦0.04, -0.03≦δ≦0.03, -0.02≦δ≦0.02, -0.01≦δ≦0.01, -0.01≦δ≦0, 0≦δ≦0.01, and 0.01≦f≦0.09, 0.02≦f≦0.08, 0.03≦f≦0.07, 0.04≦f≦0.06, 0.05≦f≦0.06, etc. Specifically, doping the oxygen sites in the positive electrode active material of the present application with this amount of F can effectively stabilize the oxygen in the positive electrode active material, thereby reducing the structural destruction caused by lattice oxygen release in the positive electrode active material, improving the stability of the material, and further improving the capacity retention rate of the battery.

[0051] It should be noted that in a positive electrode plate, a battery, or a power consumption device, oxygen elements in the positive electrode active material are lost as the battery undergoes cycles and other processes, resulting in a situation where the measured oxygen content 2+δ-f in the positive electrode active material is less than 2.

[0052] In some embodiments of the present application, the positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F f In the formula, 1.75≦(a+b+c) / b≦9.5, for example, 1.8≦(a+b+c) / b≦9.5, 1.9≦(a+b+c) / b≦9.4, 2≦(a+b+c) / b≦9.3, 2.1≦(a+b+c) / b≦9.2, 2.2≦(a+b+c) / b≦9.1, 2.3≦(a+b+c) / b≦9, 2.5≦(a+b+c) / b≦8.5, 3≦(a+b+c) / b≦8, 3.5≦(a+b+c) / b≦7.5, 4≦(a+b+c) / b≦7, 4.5≦(a+b+c) / b≦6.5, 5≦(a+b+c) / b≦6, 5≦(a+b+c) / b≦5.5, etc. Specifically, by controlling the ratio of the Fe content to the sum of the contents of Ni, Fe, and Mn in the positive electrode active material within the above range, on the one hand, it is possible to reduce the decrease in the number of Na ions that can be desorbed from the positive electrode active material, which would otherwise be caused by an excessively small amount of Fe, a metal component with a variable valence, and to provide the positive electrode active material with excellent specific capacity, and on the other hand, it is possible to reduce the effect of a large amount of Fe migrating to the Na ion layer, which would otherwise be caused by an excessively large Fe content in the positive electrode active material, on the effect on the desorption and occlusion of Na ions, and to improve the cycle performance of the positive electrode active material, thereby improving the capacity retention rate of a battery containing it.

[0053] In some embodiments of the present application, the positive electrode active material Na x Ni a Fe b Mn c M1 d M2 e O 2+δ-f F fwhere 0.8 < x ≤ 1.0, the phase state of the positive electrode active material includes the O3 phase, and the space group is including TIFF2026508647000003.tif6168, and the interlayer spacing is 0.53 nm - 0.55 nm. For example, x may be 0.82 - 1.0, 0.85 - 0.95, 0.88 - 0.90, etc., and the interlayer spacing may be 0.53 nm - 0.545 nm, 0.535 nm - 0.54 nm, 0.536 nm - 0.539 nm, etc. Specifically, x is within the above range, and the Na content of the formed O3-phase positive electrode active material is high, and more Na ions can be desorbed, increasing the capacity of the battery.

[0054] In some embodiments of the present application, 0.6 ≤ x ≤ 0.8, the phase state of the positive electrode active material includes the P2 phase, the space group includes P63 / mmc, and the interlayer spacing is 0.54 nm - 0.57 nm. For example, x may be 0.6 - 0.78, 0.65 - 0.75, 0.68 - 0.7, etc., and the interlayer spacing may be 0.54 nm - 0.565 nm, 0.545 nm - 0.56 nm, 0.55 nm - 0.555 nm, etc. Specifically, x is within the above range, and the formed P2-phase positive electrode active material has a large interlayer spacing, improving the transport rate of Na ions and maintaining the integrity of the layered structure, giving the battery excellent rate performance and cycle performance.

[0055] It should be noted that the method for conditioning the phase state, space group, and interlayer spacing of the positive electrode active material in the present application may be X-ray diffraction, scanning electron microscope, transmission electron microscope, etc. Specifically, in the X-ray diffraction pattern, the characteristic peak within the range of 40.5° to 42.5° indicates that the positive electrode active material is the O3 phase, and the space group is including TIFF2026508647000004.tif61, and the characteristic peak within the range of 48° to 50° indicates that the positive electrode active material is the P2 phase, the space group includes P63 / mmc, and the interlayer spacing of the above O3-phase positive electrode active material can be obtained by calculating based on the (003) peak position of X-ray diffraction, and the interlayer spacing of the above P2-phase positive electrode active material can be obtained by calculating based on the (002) peak position of X-ray diffraction.

[0056] In some embodiments of the present application, the pH value of the positive electrode active material immersion solution is 13 or less, for example, the pH value of the positive electrode active material immersion solution may be 7-13, 7.2-13, 7.5-13, 8-13, 8.5-13, 9-13, 10-12.9, 10.5-12.7, 11.0-12.7, 11.2-12.5, 11.5-12.3, 11.7-12.0, etc. Controlling the pH value of the positive electrode active material immersion solution within the above range reduces gel formation during the slurrying process and facilitates subsequent application of the positive electrode active material slurry. In some other embodiments of the present application, the pH value of the positive electrode active material immersion solution is 12.7 or less, for example, the pH value of the positive electrode active material immersion solution is 11.0≦pH≦12.7.

[0057] Specifically, the pH value of the immersion solution for the positive electrode active material can be measured using the following method: The positive electrode active material was dispersed in pure water, immersed, and filtered to obtain an immersion liquid, which was weighed and titrated with a standard hydrochloric acid solution.

[0058] In some embodiments of the present application, the D v 50 is 3 μm-30 μm, for example, the D of the positive electrode active material v In some other embodiments of the present application, the D 50 of the positive electrode active material may be 3 μm-29 μm, 4 μm-28 μm, 5 μm-15 μm, 6 μm-14 μm, 8 μm-13 μm, 9 μm-12 μm, 10 μm-11 μm, etc. v 50 is 5 μm-15 μm.

[0059] In the present application, Dv50 refers to the particle size corresponding to the cumulative volume distribution percentage reaching 50%, measured using a laser particle size analyzer (e.g., Malvern Master Size 3000), e.g., with reference to standard GB / T 19077-2016.

[0060] In some embodiments of the present application, the specific surface area of ​​the positive electrode active material is 0.1 m 2 / g-5m2 / g, and for example, the specific surface area of ​​the positive electrode active material is 0.1 m 2 / g-4.5m 2 / g, 0.2m 2 / g-4m 2 / g, 0.3m 2 / g-3m 2 / g, 0.5m 2 / g-2.5m 2 / g, 1m 2 / g-2m 2 / g, 1.2m 2 / g-1.8m 2 In some other embodiments of the present application, the specific surface area of ​​the positive electrode active material may be 0.3 m 2 / g-3m 2 / g.

[0061] In this application, the specific surface area of ​​the positive electrode active material can be obtained by testing with reference to the following method: using a multi-station fully automatic specific surface area and pore size analyzer Gemini VII 2390 from Micromeritics, USA, take approximately 7 g of sample and place it in a 9 cc long tube with a bubbler, degas at 200°C for 2 hours, and then place it in the tube and test to obtain the BET (specific surface area) data of the positive electrode active material.

[0062] In some embodiments of the present application, the tap density of the positive electrode active material is 1 g / cm 3 -3g / cm 3 For example, the tap density of the positive electrode active material is 1 g / cm 3 -2.8g / cm 3 , 1.5g / cm 3 -2.5g / cm 3 , 1.7g / cm 3 -2.4g / cm 3 , 1.8g / cm 3 -2.g / cm 3 In some other embodiments of the present application, the tap density of the positive electrode active material may be 1.5 g / cm 3 -2.5g / cm 3 is.

[0063] In this application, the tap density refers to the mass per unit volume measured after tapping the powder in a container under predetermined conditions. The tap density of the positive electrode active material is measured as follows: The weighed positive electrode active material was placed in the measuring cylinder of the tapping device, and the measuring cylinder was fixed to a support stand. The cam was rotated, and the orientation rod was driven so that the support stand slid up and down and collided with the anvil. The vibration was performed at 250±15 times per minute for 12 minutes. The volume of the positive electrode active material in the measuring cylinder was measured, and the ratio of the mass to the volume of the positive electrode active material was the tap density of the positive electrode active material.

[0064] The formula for calculating tap density is ρbt=m0 / V.

[0065] where ρbt is tap density, g / cm 3 m0 - mass of positive electrode active material, g V - Volume of the positive electrode active material after tapping (volume of the beaker), cm 3 .

[0066] In some embodiments of the present application, the positive electrode active material has a compacted density of 3.0 g / cm at a pressure of 300 MPa. 3 -4.0g / cm 3 For example, the compaction density of the positive electrode active material under a pressure of 300 MPa is 3.0 g / cm 3 -3.9g / cm 3 , 3.1g / cm 3 -3.8g / cm 3 , 3.2g / cm 3 -3.7g / cm 3 , 3.3g / cm 3 -3.6g / cm 3 , 3.4g / cm 3 -3.5g / cm 3 etc. may also be used.

[0067] In some embodiments of the present application, the compaction density refers to the compaction density of the electrode plate after the material is manufactured into the electrode plate. Compaction density = areal density / (thickness of electrode plate after rolling - thickness of current collector). Specifically, the compaction density of the positive electrode active material at a pressure of 300 MPa is measured as follows: After roll pressing, the electrode plate was taken and a region with an area of ​​s was cut out using a circular or rectangular cutter. The thickness was measured as a and the weight was measured as m1. The positive electrode material was washed off with an acetone-alcohol mixture and dried. The remaining aluminum foil was weighed as m2 and its thickness was measured as b. The difference between the two weights was divided by the circular or rectangular area s to calculate the areal density, i.e., areal density = (m1 - m2) / s. Dividing the areal density by the difference in thickness yields the compacted density, i.e., compacted density = (m1 - m2) / [s(ab)].

[0068] Specifically, the positive electrode active material D of the present application v When at least one of the specific surface area, tap density, and compaction density at a pressure of 300 MPa is within the above range, the conduction distance within the positive electrode active material is small, the surface side reactions are reduced, the positive electrode active material is promoted to exert its gram capacity, and the capacity retention rate of a battery containing it is improved.

[0069] A second aspect of the present application provides a method for producing the cathode active material according to the first aspect, the method comprising: S100: A precursor is obtained by mixing a Na source, a Ni source, an Fe source, a Mn source, an M1 source, and an M2 source. In some embodiments of the present application, the Na source, Ni source, Fe source, Mn source, M1 source, and M2 source are mixed according to the composition of the positive electrode active material.

[0070] It should be noted that the Na source, Ni source, Fe source, Mn source, M1 source, and M2 source in the present application are common materials in the field, and those skilled in the art can select them according to the actual situation. For example, the Na source may include at least one of Na2CO3, NaHCO3, NaOH, and Na2O2; the Ni source may include NiO; the Fe source may include at least one of FeO, Fe2O3, and Fe3O4; the Mn source may include at least one of Mn2O3, Mn3O4, MnO, and MnO2; the M1 source may include at least one of an oxide of M1, an M1-containing salt, and other compounds; and the M2 source may include at least one of an oxide of M2, an M2-containing salt, and other compounds.

[0071] It should be noted that when the positive electrode active material needs to be doped with F element, at least one of the Na source, Ni source, Fe source, Mn source, M1 source, and M2 source employs at least one of its corresponding fluorine-containing salt and other compounds, such as sodium fluoride, nickel fluoride, iron fluoride, manganese fluoride, M1 fluoride (fluoride salt of M1), and M2 fluoride (fluoride salt of M2).

[0072] S200: Calcining the precursor In some embodiments of the present application, the obtained precursor is placed in a muffle furnace and calcined in an air atmosphere, then cooled to room temperature, and then mechanically pulverized to obtain the positive electrode active material, wherein the calcination temperature may be 600°C-1200°C, such as 600°C-1100°C, 700°C-1000°C, 800°C-900°C, etc., and the incubation time may be 10 hours-20 hours, such as 10 hours-19 hours, 11 hours-18 hours, 12 hours-17 hours, 13 hours-16 hours, 14 hours-15 hours, etc.

[0073] Furthermore, if necessary, the precursor may be pre-calcined and kept warm before being calcined. The pre-calcination temperature may be 600°C-900°C, such as 600°C-850°C, 650°C-800°C, 600°C-750°C, 550°C-700°C, 500°C-650°C, or 550°C-600°C. The warming time may be 10 hours-20 hours, such as 10 hours-19 hours, 11 hours-18 hours, 12 hours-17 hours, 13 hours-16 hours, or 14 hours-15 hours.

[0074] This allows the production of a positive electrode active material having the above-mentioned excellent air stability and cycle stability using a solid phase method, thereby improving the capacity retention rate of the battery.

[0075] A third aspect of the present application provides another method for producing the cathode active material according to the first aspect, the method comprising: Sa: A mixed solution is obtained by mixing a Ni source, an Fe source, a Mn source, an M1 source, and an M2 source with water. In some examples in the present application, a Ni source, an Fe source, a Mn source, an M1 source, and an M2 source are mixed with water according to the composition of the positive electrode active material to obtain a mixed solution.

[0076] It should be noted that the Ni source, Fe source, Mn source, M1 source, and M2 source in the present application are common materials in the field, and those skilled in the art can select them according to actual circumstances. For example, the Ni source may include at least one of nickel chloride, nickel sulfate, nickel nitrate, and nickel oxalate; the Fe source may include at least one of iron chloride, iron sulfate, iron nitrate, and iron oxalate; the Mn source may include at least one of manganese chloride, manganese sulfate, manganese nitrate, and manganese oxalate; the M1 source may include at least one of chloride, sulfate, nitrate, and oxalate of M1; and the M2 source may include at least one of chloride, sulfate, nitrate, oxalate, and other compounds of M2.

[0077] Sb: The solution is reacted with a precipitant to obtain a precursor. In some embodiments of the present application, the solution obtained in step Sa is reacted with a solution containing a precipitant to obtain a precursor, wherein the solution containing a precipitant comprises at least one of aqueous ammonia, carbonic acid, and oxalic acid.

[0078] Sc: Precursor and Na source are mixed and then calcined In some embodiments of the present application, the obtained precursor and the Na source are mixed according to the composition of the positive electrode active material, and then ball milled or mechanically stirred to achieve uniform mixing. The mixture is then calcined in a muffle furnace, cooled to room temperature, and mechanically pulverized to obtain the positive electrode active material. The calcination temperature is 600°C-1200°C, and may be, for example, 700°C-1100°C, 800°C-1000°C, 900°C-950°C, etc. The calcination atmosphere may be air or an oxygen gas atmosphere. The incubation time is 10 hours-20 hours, and may be, for example, 10 hours-19 hours, 11 hours-18 hours, 12 hours-17 hours, 13 hours-16 hours, or 14 hours-15 hours, etc.

[0079] It should be noted that, if necessary, the precursor Na source may be mixed in advance and then pre-baked and kept at a temperature before mixing and calcining the precursor and Na source. The pre-baking temperature may be 600°C-900°C, such as 600°C-850°C, 650°C-800°C, 600°C-750°C, 550°C-700°C, 500°C-650°C, or 550°C-600°C, and the keeping time may be 10 hours-20 hours, such as 10 hours-19 hours, 11 hours-18 hours, 12 hours-17 hours, 13 hours-16 hours, or 14 hours-15 hours. The Na source may include at least one of Na2CO3, NaHCO3, NaOH, and Na2O2.

[0080] It should be noted that when the positive electrode active material needs to be doped with F element, at least one of the Na source, Ni source, Fe source, Mn source, M1 source, and M2 source employs at least one of its corresponding fluorine-containing salt and other compounds, such as sodium fluoride, nickel fluoride, iron fluoride, manganese fluoride, M1 fluoride (fluoride salt of M1), and M2 fluoride (fluoride salt of M2).

[0081] This allows the production of a positive electrode active material having the above-mentioned excellent air stability and cycle stability using the coprecipitation method, thereby improving the capacity retention rate of the battery.

[0082] A fourth aspect of the present application provides a positive electrode plate comprising the positive electrode active material according to the first aspect of the present application, the positive electrode active material produced by the method according to the second aspect, or the positive electrode active material produced by the method according to the third aspect.

[0083] The positive electrode plate generally includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.

[0084] The positive electrode current collector may be a conventional metal foil sheet or a composite current collector (a composite current collector may be formed by depositing a metal material on a polymer substrate.) For example, the positive electrode current collector may include at least one of copper foil, aluminum foil, nickel foil, stainless steel foil, stainless steel mesh, and carbon-coated aluminum foil.

[0085] The positive electrode active material includes the positive electrode active material according to the first aspect of the present application, a positive electrode active material produced by the method according to the second aspect, or a positive electrode active material produced by the method according to the third aspect.

[0086] The positive electrode active material layer may optionally further include a conductive agent and an adhesive, the conductive agent being used to improve the conductivity of the positive electrode active material layer, and the adhesive being used to firmly adhere the positive electrode active material and the adhesive to the positive electrode current collector. The present application does not specifically limit the types of the conductive agent and the adhesive, and they may be selected according to actual needs.

[0087] For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, and the adhesive may include at least one of styrene butadiene rubber (SBR), water-based acrylic resin, carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), and polyvinyl alcohol (PVA).

[0088] All of these materials are commercially available.

[0089] A fifth aspect of the present application provides a battery including the positive electrode plate according to the fourth aspect of the present application, whereby the battery has an excellent capacity retention rate.

[0090] The battery is a battery that can be continuously used by activating the active material through a method of charging after discharging.

[0091] As can be seen, the battery according to the present application is a sodium ion battery.

[0092] Generally, a battery includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. During charging and discharging, active ions shuttle between the positive and negative electrodes, absorbing and desorbing. The separator is placed between the positive and negative electrodes to provide isolation. The electrolyte conducts ions between the positive and negative electrodes.

[0093] [Negative electrode plate] In a battery, the negative electrode plate generally includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

[0094] The negative electrode current collector may be a conventional metal foil sheet or a composite current collector (e.g., a metal material may be deposited on a polymer substrate to form a composite current collector). For example, the negative electrode current collector may be a copper foil.

[0095] The specific type of the negative electrode active material is not limited, and any active material known in the art for use in sodium-ion battery negative electrodes may be used. Those skilled in the art can select the material according to their actual needs. For example, the negative electrode active material may include, but is not limited to, at least one of sodium metal, a carbon material, an alloy material, a transition metal oxide and / or sulfide, a phosphorus-based material, and a titanate material. Specifically, the carbon material may include at least one of hard carbon, soft carbon, amorphous carbon, and a nanostructured carbon material. The alloy material may include an alloy material formed from at least one of Si, Ge, Sn, Pb, and Sb. The transition metal oxides and sulfides have a general formula of MxNy, where M includes at least one of Fe, Co, Ni, Cu, Mn, Sn, Mo, Sb, and V, and N includes O or S. The phosphorus-based material may include at least one of red phosphorus, white phosphorus, and black phosphorus. The titanate material may include Na2Ti3O7, Na2Ti6O 13 , Na4Ti5O 12 , Li4Ti5O 12 , NaTi2(PO4)3. All of these materials are commercially available.

[0096] The negative electrode active material layer may further include an adhesive and a conductive agent, the conductive agent being used to improve the conductivity of the negative electrode active material layer, and the adhesive being used to firmly adhere the negative electrode active material and the adhesive to the negative electrode current collector. The present application does not specifically limit the types of the conductive agent and the adhesive, and they may be selected according to actual needs.

[0097] By way of example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0098] By way of example, the adhesive may include at least one of styrene butadiene rubber (SBR), styrene butadiene rubbers (SBCs), water-based acrylic resins, and carboxymethyl cellulose (CMC).

[0099] The negative electrode active material layer may further optionally contain a thickener, such as carboxymethyl cellulose (CMC), but the present application is not limited thereto and may further use other materials that can be used as thickeners for negative electrode plates of sodium ion batteries.

[0100] [Electrolyte] The electrolytic solution may include an electrolyte salt and a solvent.

[0101] By way of example, the electrolyte sodium salt may include at least one of sodium hexafluorophosphate, sodium difluoro(oxalato)borate, sodium tetrafluoroborate, sodium bis(oxalato)borate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethylsulfonate, and sodium di(trifluoromethylsulfonyl)imide.

[0102] By way of example, the solvent may include at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0103] In some embodiments, the electrolyte solution further includes additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may further include additives that can improve some battery performance, such as an additive that improves the overcharge performance of the battery, an additive that improves the high-temperature performance of the battery, or an additive that improves the low-temperature performance of the battery.

[0104] [Separator] The present application does not particularly limit the separator, and any known porous structure separator having electrochemical stability and mechanical stability can be selected and used according to actual needs, and may include, for example, a single-layer or multi-layer film containing at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0105] The embodiments of the present application are not particularly limited to the shape of the battery, which may be cylindrical, rectangular, or any other shape. Figure 1 shows a battery 1 with a rectangular structure as an example.

[0106] In some embodiments, the battery may include an outer casing, which is used to package the positive and negative electrodes and the electrolyte.

[0107] In some embodiments, the exterior body may include a case and a cover plate. Here, the case may include a bottom plate and a side plate connected to the bottom plate, the bottom plate and the side plate surroundingly forming a storage cavity. The case has an opening communicating with the storage cavity, and the cover plate can cover the opening to seal the storage cavity.

[0108] The positive electrode plate, the negative electrode plate, and the separator can be wound or stacked to form an electrode assembly, which is then packaged in the receiving cavity. The number of electrode assemblies included in the battery can be one or more, and can be adjusted according to needs.

[0109] In some embodiments, the battery exterior may include a hard case, such as a hard plastic case, an aluminum case, or a steel case.

[0110] The exterior of the battery may include a pouch, for example, a bag-like pouch, and the material of the pouch may include at least one of plastics such as polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0111] In some embodiments, the batteries can be assembled into a battery module, and the number of batteries included in the battery module can be multiple, with the specific number being adjustable depending on the application and capacity of the battery module.

[0112] FIG. 2 shows an example of a battery module 2. Referring to FIG. 2, in the battery module 2, the plurality of batteries 1 may be arranged in order along the longitudinal direction of the battery module 2. Of course, they may be arranged in any other manner. Furthermore, the plurality of batteries 1 may be fixed by fasteners.

[0113] The battery module 2 may further include a housing having an accommodating space, and the plurality of batteries 1 are accommodated in the accommodating space. In some embodiments, the battery module may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0114] 3 and 4 show an example of a battery pack 3. Referring to FIGS. 3 and 4, the battery pack 3 may include a battery box and a plurality of battery modules 2 installed in the battery box. The battery box includes an upper housing 4 and a lower housing 5, and the upper housing 4 can be attached to the lower housing 5 as a lid, forming a sealed space for accommodating the battery modules 2. The plurality of battery modules 2 may be arranged in the battery box in any manner.

[0115] A sixth aspect of the present application provides a power consuming device including the battery according to the fifth aspect. Specifically, the battery may serve as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships, satellites, and energy storage systems.

[0116] Figure 5 shows an example power consumer, which may include a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0117] Other examples of power consuming devices may include mobile phones, tablet computers, and laptops, which generally require a low profile and may employ batteries as a power source.

[0118] In order to clarify the technical problems, technical solutions, and beneficial effects solved by the embodiments of the present application, the following will be described in more detail in conjunction with the embodiments and drawings. Obviously, the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and does not constitute any limitation on the present application and its applications. All other embodiments obtained by those skilled in the art based on the embodiments in the present application without any creative effort are within the scope of protection of the present application.

[0119] Example 1 [NaNi 0.2 Fe 0.2 Mn 0.5 La 0.02 Cu 0.08 O2 Production] The raw materials were mixed in the agate ball mill tank of a planetary ball mill according to the stoichiometric ratio of the molecular formula: 23.666 g of Na2CO3, 6.672 g of NiO, 7.131 g of Fe2O3, 17.627 g of Mn2O3, 1.455 g of La2O3, and 2.841 g of CuO (the molar ratio of Na, Ni, Fe, Mn, La to Cu was 1:0.2:0.2:0.5:0.02:0.08). The raw materials were ground at a rotation speed of 600 r / min, and then heated to 950°C at a heating rate of 5°C / min in a muffle furnace. After sintering for 15 hours, the material was allowed to cool naturally to room temperature to produce the black positive electrode active material NaNi. 0.2 Fe 0.2 Mn 0.5 La 0.02 Cu 0.08 Got O2.

[0120] [Production of positive electrode plates] The above-produced NaNi 0.2 Fe 0.2 Mn 0.5 La 0.02 Cu0.08 O2, conductive agent carbon black, adhesive polyvinylidene fluoride (PVDF), and N-methylpyrrolidone (NMP) were uniformly mixed and stirred in a weight ratio of 60:5:5:30 to obtain a positive electrode slurry. The positive electrode slurry was then uniformly applied to a positive aluminum foil current collector, dried, cold pressed, and slit to obtain a positive electrode plate.

[0121] [Manufacturing of negative electrode plates] A metallic sodium sheet was used for the negative electrode plate.

[0122] [Electrolyte production] In a glove box with an argon gas atmosphere (H2O<0.1 ppm, O2<0.1 ppm), the organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed uniformly at a volume ratio of 3 / 7 to obtain a mixed solvent. NaPF6 was then dissolved in the mixed solvent and stirred uniformly to obtain an electrolyte with a sodium salt concentration of 1 mol / L.

[0123] [Separator] Glass fiber was used as the separator.

[0124] The positive electrode plate, separator, and negative electrode plate are folded in this order, with the separator positioned between the positive and negative electrode plates to provide isolation, and then wound up to obtain an electrode assembly. The electrode assembly is placed in an outer casing, and the above-prepared electrolyte is injected into the dried secondary battery. The secondary battery is then vacuum packaged, left to stand, chemically formed, and shaped to obtain the secondary battery.

[0125] The secondary batteries containing the positive electrode active materials of Examples 2-24 and Comparative Examples 1-4 were the same as Example 1 except for the different parameters (see Table 1).

[0126] The compositions of the positive electrode active materials in the batteries of Examples 1-24 and Comparative Examples 1-4 of the present application are as shown in Table 1.

[0127] [Table 1] TIFF2026508647000006.tif225168TIFF2026508647000007.tif57144

[0128] D of the positive electrode active material in Examples 1-24 and Comparative Examples 1-4 v 50, specific surface area, tap density, compaction density at a pressure of 300 MPa, pH value of the immersion solution, phase state, space group and interlayer spacing, as well as the capacity and capacity retention rate of the resulting sodium ion battery were conditioned, and the conditioning results are shown in Table 2.

[0129] Performance test: 1. Testing the phase, space group and layer spacing of the positive electrode active material: An XRD pattern is prepared for the positive electrode active material, and the phase and space group of the positive electrode active material are determined according to the position of the characteristic peak in the XRD pattern. The layer spacing d of the positive electrode active material is calculated according to the position of the (003) peak or (002) peak of the X-ray diffraction and the corresponding peak and the formula d = λ / (2 sin θ). In the formula d = λ / (2 sin θ), the radiation wavelength λ = 1.5406 Å, and the characteristic peak is scanned within the 2θ angle range of 40.5° to 42.5°. This indicates that the positive electrode active material is O3 phase, and the space group is: Scanning the characteristic peaks within the 2θ angle range of 48° to 50°, including TIFF2026508647000008.tif6168, indicates that the positive electrode active material is a P2 phase, and the space group includes P63 / mmc.

[0130] 2. Positive electrode active material D v 50 Measurement: Measured using a Malvern Master Size 3000 laser particle size analyzer in accordance with GB / T 19077-2016.

[0131] 3. Tap density measurement: The weighed positive electrode active material was placed in the measuring cylinder of the tapping device, and the measuring cylinder was fixed to a support stand. The cam was rotated, and the orientation rod drove the support stand to slide up and down, colliding with the anvil. The vibration was performed at 250±15 vibrations per minute for 12 minutes. The volume of the positive electrode active material in the measuring cylinder was measured, and the ratio of the mass to the volume of the positive electrode active material was the tap density of the positive electrode active material.

[0132] The formula for calculating tap density is ρbt=m0 / V.

[0133] where ρbt is tap density, g / cm 3 m0 - mass of positive electrode active material, g V - Volume of the positive electrode active material after tapping (volume of the beaker), cm 3 .

[0134] 4. Compaction density of positive electrode active material at a pressure of 300 MPa: After roll pressing, the electrode plate was taken and a region with an area of ​​s was cut out using a circular or rectangular cutter. The thickness was measured as a and the weight was measured as m1. The positive electrode material was washed off with an acetone-alcohol mixture and dried. The weight of the remaining aluminum foil was measured as m2 and the thickness of the aluminum foil was measured as b. The difference between the two weights was divided by the area of ​​the circle or rectangle, s, to calculate the areal density, i.e., areal density = (m1 - m2) / s. The areal density was then divided by the difference in thickness to obtain the compaction density, i.e., compaction density = (m1 - m2) / [s(ab)].

[0135] 5. Measurement of pH value of immersion solution for positive electrode active material: The positive electrode active material was dispersed in pure water and immersed, and filtered to obtain the immersion solution, which was weighed and titrated with a standard hydrochloric acid solution.

[0136] 6. Capacity test of positive electrode plate: Prepare a positive electrode plate, prepare a negative electrode plate, punch out a mold, weigh, select the mass of the positive and negative electrode plates according to the type of positive and negative electrode material, and then pair them accordingly. Then place them in a glove box for 2 hours, electrically assemble the glove box, and clamp the prepared button battery in an electrochemical test cabinet. Calculate the charge and discharge current based on the test rate (0.2C, 1C, 3C, 5C). In the formula: current = rate × theoretical gram capacity × (M2-M1) × ω%, the theoretical gram capacity is determined based on the theoretical gram capacity of the positive electrode material. M2 - actual weight of electrode plate, M1 - average weight of the current collector, ω% - actual mass fraction of active material 7. Battery capacity retention test: Using Example 1 as an example, the secondary battery was charged at a constant current of 0.1 C at 25°C to a charge cutoff voltage of 4.2 V, then discharged at 0.1 C to 1.5 V, allowed to stand for 5 minutes, and then discharged at a constant current of 0.5 C to a discharge cutoff voltage of 2.8 V, allowed to stand for 5 minutes, and the battery discharge capacity C0 at this time was recorded. According to this method, the battery was subjected to 500 charge-discharge cycles, and the battery discharge capacity after 500 cycles was recorded as C1.

[0137] Cycle capacity retention rate of secondary battery = C1 / C0 × 100%.

[0138] The test process for the capacity retention rate of the secondary batteries of Examples 2-24 and Comparative Examples 1-4 was the same as above.

[0139] The XRD patterns of the cathode active materials of Example 1, Comparative Example 1, and Comparative Example 2 are shown in FIGS. 6 and 7. In Comparative Example 1, the ratio d / c of ​​the rare earth element M1 to Mn in the cathode active material was 0.004, which was smaller than 0.005, compared to Example 1. This meant that the peak between 10-20°C in the cathode active material was not significant, and the hetero-peak between 30-40°C was more significant. This indicates that the amount of rare earth element was too small, which is detrimental to improving the air stability and cycle stability of the cathode active material. In Comparative Example 2, the ratio d / c of ​​the rare earth element M1 to Mn in the cathode active material was 0.06, which was larger than 0.05, compared to Example 1. This indicates that the cathode active material had a significant hetero-peak. This indicates that the amount of rare earth element was too large, and that the rare earth element aggregated on the surface of the cathode active material due to insufficient solid solubility between the rare earth element and Mn, forming a hetero-phase.

[0140] FIG. 8 shows the charge / discharge curves at 0.1 C for the first cycle of the sodium ion battery produced in Example 1, and shows that the operating voltage range of the battery is 1.5 V to 4.2 V.

[0141] A comparison of the capacity retention rates of Example 1 and Comparative Example 4 is shown in FIG. 9, and it can be seen that the capacity retention rate of Example 1 of the present application is clearly superior to that of Comparative Example 4.

[0142] [Table 2]

[0143] As can be seen from Table 2, in the examples of the present application, NiFeMn is used as the main body material and is doped with a rare earth element M1 and a doping element M2, and the ratio of the rare earth element M1 to Mn is controlled to improve the air stability and cycle stability of the positive electrode active material, thereby improving the capacity retention of the battery containing it. Compared to the examples, the values ​​of d / c in Comparative Examples 1 and 2 were outside the range of the examples of the present application, and the values ​​of the Mn content c in Comparative Examples 3 and 4 were outside the range of the examples of the present application, resulting in a significant decrease in both the capacity retention and capacity of the battery containing them.

[0144] Finally, it should be noted that the above embodiments are merely for illustrating the technical solutions of the present application, and are not intended to limit the same. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications may still be made to the technical solutions described in the above embodiments, or equivalent substitutions may be made for some or all of the technical features therein. Such modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and should all be included in the scope of the claims and description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in the embodiments may be combined in any manner. The present application is not limited to the specific embodiments disclosed in the description, but includes all technical solutions included within the scope of the claims. [Explanation of symbols]

[0145] 1: Secondary battery, 2: Battery module, 3: Battery pack, 4: Upper housing, 5: Lower housing.

Claims

1. A positive electrode active material, wherein the positive electrode active material comprises: Na ｘ Ni ａ Fe ｂ Mn ｃ M1 ｄ M2 ｅ O ２＋δ－ｆ F ｆ Including, wherein M1 includes a rare earth element, M2 includes at least one of a Group IA element, a Group IIA element, a Group IIIA element, a Group IVA element, a Group VA element, a Group VIA element, and a transition element, and the following relationships are satisfied: 0.6≦x≦1.2, 0<a≦0.5, 0<b≦0.4, 0.3≦c≦0.75, 0.001≦d≦0.05, 0≦e≦0.3, −0.1≦δ≦0.1, 0≦f≦0.1, 0.005≦d / c≦0.05, and a+b+c+d+e=1.

2. 2. The positive electrode active material of claim 1, wherein the rare earth element comprises at least one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

3. 3. The positive electrode active material according to claim 1, wherein M2 includes at least one of B, Mg, Al, Si, K, Ca, Ga, Ge, Se, Rb, Sr, In, Sn, Sb, Te, Sc, Ti, V, Cr, Co, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, and Au.

4. The positive electrode active material according to claim 1 , wherein 0.01≦d / c≦0.

03.

5. The positive electrode active material is 0.1≦a≦0.4, and optionally 0.15≦a≦0.3; 0.1≦b≦0.35, and optionally 0.15≦b≦0.35; The positive electrode active material according to claim 1 , which satisfies at least one of the conditions: 0.35≦c≦0.6, and optionally 0.35≦c≦0.

5.

6. 6. The positive electrode active material according to claim 1, wherein 1.75≦(a+b+c) / b≦9.5, optionally 2≦(a+b+c) / b≦9.5, and further optionally 2≦(a+b+c) / b≦6.

3.

7. 0.8<x≦1.0, the phase state of the positive electrode active material includes an O3 phase, and the space group is The positive electrode active material according to any one of claims 1 to 6, wherein the layer spacing is 0.53 nm to 0.55 nm.

8. 7. The positive electrode active material according to claim 1, wherein 0.6≦x≦0.8, the phase state of the positive electrode active material includes a P2 phase, the space group includes a P63 / mmc, and the layer spacing is 0.54 nm to 0.57 nm.

9. 9. The cathode active material according to claim 1, wherein the pH value of the immersion liquid for the cathode active material is 13 or less, optionally, the pH value of the immersion liquid for the cathode active material is 12.7 or less, and further optionally, the pH value of the immersion liquid for the cathode active material satisfies 11.0≦pH≦12.

7.

10. The positive electrode active material is D of the positive electrode active material ｖ 50 is 3 μm-30 μm, and optionally 5 μm-15 μm; The specific surface area of ​​the positive electrode active material is 0.1 m ２ / g-5m ２ / g, and optionally 0.3m ２ / g-3m ２ / g, and The tap density of the positive electrode active material is 1 g / cm ３ -3 g / cm ３ and optionally 1.5 g / cm ３ -2.5 g / cm ３ and The compaction density of the positive electrode active material at a pressure of 300 MPa is 3.0 g / cm ３ -4.0 g / cm ３ The positive electrode active material according to claim 1 , wherein at least one of the following conditions is satisfied:

11. mixing a Na source, a Ni source, an Fe source, a Mn source, an M1 source, and an M2 source to obtain a precursor; and calcining the precursor to obtain the positive electrode active material.

12. mixing a Ni source, an Fe source, a Mn source, an M1 source, and an M2 source with water to obtain a mixed solution; reacting the solution with a precipitating agent to obtain a precursor; The method for producing a positive electrode active material according to claim 1 , comprising mixing the precursor and a Na source and then calcining the mixture to obtain a positive electrode active material.

13. A positive electrode plate comprising the positive electrode active material according to any one of claims 1 to 10 or the positive electrode active material produced by the method according to claim 11 or 12.

14. A battery comprising the positive electrode plate of claim 13.

15. 15. A power consuming device comprising the battery of claim 14.

Images