Positive electrode active material and method for producing the same, positive electrode plate, secondary battery, battery module, battery pack, and power consumption device

Abstract

The present application provides a mixed positive electrode active material and a manufacturing method thereof, a positive electrode plate, a secondary battery, a battery module, a battery pack and a power consumption device. The positive electrode active material includes a first positive electrode active material and a second positive electrode active material, where the first positive electrode active material is a compound LiNi b Co d Mn e M f O2, and the second positive electrode active material is the compound Li a A x Mn 1-y B y P 1-z C z O 4-n D n The present application improves the cycle capacity retention rate of a secondary battery, extends the cycle life of the secondary battery, and improves the safety of the secondary battery by using a mixture of a first positive electrode active material and a second positive electrode active material.

Description

[Technical Field]

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

[0002] In recent years, the application range of secondary batteries has become increasingly broad. They are widely used in energy storage power systems, such as hydroelectric, thermal, wind, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. As secondary batteries have made rapid progress, higher requirements are being placed on their energy density, cycle performance, and safety performance. The conventional positive electrode active material for secondary batteries, lithium manganese phosphate, is prone to Li / Mn antisite defects during charging and discharging, resulting in relatively serious manganese leaching, which affects the gram capacity of the secondary battery and leads to poor safety and cycle performance. Summary of the Invention [Problem to be solved by the invention]

[0003] The present application has been made in view of the above-mentioned problems, and aims to provide a positive electrode active material, a method for manufacturing a positive electrode active material, a positive electrode plate, a secondary battery, a battery module, a battery pack, and a power consumption device that solve the problems of low cycle capacity retention, short cycle life, and low safety of secondary batteries manufactured using conventional positive electrode active materials. [Means for solving the problem]

[0004] 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 including a first positive electrode active material and a second positive electrode active material, wherein: The first positive electrode active material is the compound LiNi b Co d Mn e M fO2, wherein b is selected from the range of 0.314 to 0.970, d is selected from the range of 0 to 0.320, optionally selected from the range of 0.047 to 0.320, e is selected from the range of 0.006 to 0.390, the sum of b, d, e and f is 1 and f is greater than 0, M is one or more elements selected from Mn, Al, Mg, Ca, Na, Ti, W, Zr, Sr, Cr, Zn, Ba, B, S and Y, optionally M is Mg and / or Al; The second positive electrode active material is the compound Li a A x Mn 1-y B y P 1-z C z O 4-n D n wherein a is selected from the range of 0.9 to 1.1, x is selected from the range of 0.001 to 0.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, n is selected from the range of 0.001 to 0.1, A is one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W, B is one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, C is one or more elements selected from B (boron), S, Si and N, and D is one or more elements selected from S, F, Cl and Br.

[0005] The present applicant has unexpectedly discovered that by simultaneously doping specific elements into the Li, Mn, P, and O sites of the compound LiMnPO4 in specific amounts to obtain a second positive electrode active material, it is possible to obtain significantly improved rate performance, significantly reduce the leaching of Mn and the elements doped into the Mn site, significantly improve cycle performance and / or high-temperature stability, improve the gram capacity and compaction density of the material, and reduce interfacial side reactions. However, because the second positive electrode active material only has one-dimensional lithium ion transmission channels, while the first positive electrode active material is a layered transition metal oxide and has two-dimensional lithium ion transmission channels, the present application uses a mixture of the first and second positive electrode active materials to complement the advantages of the two materials, thereby improving the cycle capacity retention rate of the secondary battery, extending the cycle life of the secondary battery, and improving the safety of the secondary battery.

[0006] Unless otherwise noted, the chemical formula is Li a A x Mn 1-y B y P 1-z C z O 4-n D n In the above, when A is two or more elements, the above-mentioned limit on the numerical range of x not only limits the stoichiometric number for each type of element that makes up A, but also limits the sum of the stoichiometric numbers of each element that makes up A. For example, when A is two or more elements A1, A2...An, the stoichiometric numbers x1, x2...xn of A1, A2...An must each fall within the numerical range in which x is limited by this application, and the sum of x1, x2...xn must also fall within this numerical range. Similarly, when B, C, and D are two or more elements, the limit on the numerical range of the stoichiometric numbers of B, C, and D in this application also has the above meaning. Similarly, a compound of the chemical formula LiNi b Co d Mn e M f When M in O2 is two or more elements, the present application also includes the above-mentioned meanings for limiting the numerical range of the stoichiometric number of M.

[0007] In one embodiment, the mass of the first positive electrode active material is m1, the mass of the second positive electrode active material is m2, and the value of m1 / (m1+m2) is 2% to 55%, and optionally 3% to 50%, such that the mass percentage of the first positive electrode active material in the two positive electrode active materials is within the above range, thereby improving the stability and safety of the entire positive electrode active material.

[0008] In any embodiment, the value of b×m1 / (m1+m2) is 0.017 to 0.457, and optionally 0.025 to 0.415, thereby further improving the stability and safety of the entire positive electrode active material.

[0009] In any embodiment, the first active cathode material is a single crystal or pseudo-single crystal material, and the particle size D of the first active cathode material is v 50 is 5.8 μm or less, optionally 2.3 to 5.8 μm, and more optionally 2.3 to 4.3 μm.

[0010] By setting the particle size of the single crystal or pseudo-single crystal first positive electrode active material within the above range, the electrochemical reaction area can be optimized, and the interfacial side reactions of the positive electrode during secondary battery cycling can be further reduced and suppressed, thereby reducing the cycle decay rate of the secondary battery and extending the cycle life of the secondary battery.

[0011] In any embodiment, when the first cathode active material is a single crystal or pseudo-single crystal material, d is selected from the range of 0.05 to 0.320, optionally selected from the range of 0.05 to 0.282, and / or b is greater than 0.314 and less than 0.97, and is selectively selected within the range of 0.55 to 0.869.

[0012] When the first positive electrode active material is a single crystal or pseudo-single crystal material, having d and b within the above ranges is advantageous for further improving the conductivity and rate performance of the positive electrode active material, further improving the cycle capacity retention rate of the secondary battery, and further extending the cycle life of the secondary battery.

[0013] In any embodiment, when the first positive electrode active material is a polycrystalline material, the particle size D of the first positive electrode active material v 50 is 3.5 to 13.5 μm, and / or The BET specific surface area of ​​the first positive electrode active material is 1.32 m 2 / g or less, and selectively 0.28~1.32m 2 / g, and / or The compaction density of the first positive electrode active material at a pressure of 3 T is 2.92 g / cm 3 or more, and selectively 2.92 to 3.31 g / cm 3 is.

[0014] By setting the particle size, specific surface area and compaction density of the polycrystalline first positive electrode active material within the above ranges, the rate performance of the positive electrode active material can be further improved, the interfacial side reactions of the positive electrode during secondary battery cycling can be further reduced and suppressed, the cycle decay rate of the secondary battery can be reduced, and the cycle life of the secondary battery can be extended.

[0015] In any embodiment, the first positive electrode active material further comprises lithium carbonate and / or lithium hydroxide; Optionally, based on the mass of the first positive electrode active material, the mass content of lithium carbonate is 1% or less and / or the mass content of lithium hydroxide is 1% or less.

[0016] Residual water molecules trapped in the second positive electrode active material may react with the electrolyte to generate HF, which is likely to cause damage to the positive electrode active material itself or the SEI film on the negative electrode plate, further affecting the life of the secondary battery. The lithium carbonate and / or lithium hydroxide further contained in the first positive electrode active material of the present application can undergo a neutralization reaction with HF, reducing or suppressing the damage caused by HF to the positive electrode active material or the SEI film on the negative electrode plate, thereby further improving the cycle life of the secondary battery.

[0017] In one embodiment, in the second positive electrode active material, A is any one element selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B is at least two elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C is any one element selected from B (boron), S, Si, and N; and D is any one element selected from S, F, Cl, and Br; Optionally, A is Mg or Nb, and / or B is at least two elements selected from Fe, Ti, V, Co and Mg, and optionally Fe and one or more elements selected from Ti, V, Co and Mg; and / or C is S, and / or D is F.

[0018] By selecting an element doped at the Li site within the above range, the lattice change rate during lithium release can be further reduced, thereby further improving the rate performance of the secondary battery. By selecting an element doped at the Mn site within the above range, the electronic conductivity can be further improved and the lattice change rate can be further reduced, thereby increasing the rate performance and gram capacity of the secondary battery. By selecting an element doped at the P site within the above range, the rate performance of the secondary battery can be further improved. By selecting an element doped at the O site within the above range, the interfacial side reactions can be further reduced and the high-temperature performance of the secondary battery can be improved.

[0019] In any embodiment, in the second positive electrode active material, x is selected from the range of 0.001 to 0.005, and / or y is selected from the range of 0.01 to 0.5, optionally selected from the range of 0.25 to 0.5, and / or z is selected from the range of 0.001 to 0.005, and / or n is selected from the range of 0.001 to 0.005.

[0020] By selecting a y value within the above range, the gram capacity and rate performance of the material can be further improved. By selecting an x ​​value within the above range, the kinetic performance of the material can be further improved. By selecting a z value within the above range, the rate performance of the secondary battery can be further improved. By selecting an n value within the above range, the high temperature performance of the secondary battery can be further improved.

[0021] In any embodiment, the value of (1-y):y is selected from the range of 1 to 4, and optionally from the range of 1.5 to 3, and the value of a:x is selected from the range of 9 to 1100, and optionally from the range of 190 to 998. This can further increase the energy density and cycle performance of the positive electrode active material.

[0022] In any embodiment, the lattice change rate of the second positive electrode active material before and after complete lithium release is 8% or less, and optionally 4% or less. Reducing the lattice change rate can facilitate Li-ion transport, i.e., the Li-ion transition ability in the material is strengthened, which is advantageous for improving the rate performance of the secondary battery. The lattice change rate can be measured by a method known in the art, for example, X-ray diffraction spectroscopy (XRD).

[0023] In any embodiment, the second positive electrode active material has a Li / Mn antisite defect concentration of 2% or less, and optionally 0.5% or less. Li / Mn antisite defects are LiMnPO4 lattice defects that are present at the Li / Mn antisite defect level. + and Mn 2+ The Li / Mn antisite defect concentration is the concentration of Mn in the positive electrode active material. 2+ Replaced by Li + Li + The percentage of the total amount. Antisite defects Mn 2+ Li +This is advantageous in improving the gram capacity and rate performance of the positive electrode active material by inhibiting the transfer of Li and reducing the concentration of Li / Mn antisite defects. The concentration of Li / Mn antisite defects can be measured by methods known in the art, such as XRD.

[0024] In one embodiment, the second positive electrode active material has a surface oxygen valence of -1.82 or less, and optionally -1.89 to -1.98. Reducing the surface oxygen valence can reduce interfacial side reactions between the positive electrode active material and the electrolyte, thereby improving the cycle performance and high-temperature stability of the secondary battery. The surface oxygen valence can be measured by methods known in the art, such as electron energy loss spectroscopy (EELS).

[0025] In any embodiment, the second positive electrode active material has a compacted density at 3 T of 2.0 g / cm 3 or more, and optionally 2.2 g / cm 3 That's all. The higher the compaction density, the greater the weight of active material per unit volume, so improving the compaction density is advantageous for improving the volumetric energy density of the cell. Compaction density can be measured in accordance with GB / T 24533-2009.

[0026] In any embodiment, the second positive electrode active material further comprises carbon, the carbon being a compound Li a A x Mn 1-y B y P 1-z C z O 4-n D n This can improve the conductivity of the positive electrode active material.

[0027] A second aspect of the present application further provides a method for producing a positive electrode active material, the method comprising: providing a first active cathode material and a second active cathode material; mixing the first positive electrode active material with the second positive electrode active material; The first positive electrode active material is the compound LiNi b Co d Mn e M f O2, and the second positive electrode active material is the compound Li a A x Mn 1-y B y P 1-z C z O 4-n D n wherein the definitions of a, b, d, e, f, x, y, z, n, M, A, B, C and D are as set out in the first aspect of the present application; Optionally, the first positive electrode active material further includes lithium carbonate and / or lithium hydroxide; Optionally, the second positive electrode active material is the compound Li a A x Mn 1-y B y P 1-z C z O 4-n D n It further includes carbon coated on the surface.

[0028] As a result, the present application uses a mixture of a first positive electrode active material and a second positive electrode active material to complement the advantages of the two materials, improve the cycle capacity retention rate of the secondary battery, extend the cycle life of the secondary battery, and improve the safety of the secondary battery.

[0029] A third aspect of the present application provides a positive electrode plate, the positive electrode plate including 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 of the first aspect of the present application or a positive electrode active material produced by the method of the second aspect of the present application, and optionally, the content of the positive electrode active material in the positive electrode film layer is 10 wt % or more, and more optionally, 95 to 99.5 wt %, based on the total weight of the positive electrode film layer.

[0030] A fourth aspect of the present application provides a secondary battery, the secondary battery including the positive electrode active material of the first aspect of the present application, or the positive electrode active material produced by the method of the second aspect of the present application, or the positive electrode plate of the third aspect of the present application.

[0031] A fifth aspect of the present application provides a battery module, which includes the secondary battery of the fourth aspect of the present application.

[0032] A sixth aspect of the present application provides a battery pack, which includes the battery module of the fifth aspect of the present application.

[0033] A seventh aspect of the present application provides a power consumption device, the power consumption device including at least one selected from the secondary battery of the fourth aspect of the present application, the battery module of the fifth aspect of the present application, and the battery pack of the sixth aspect of the present application. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Figure 2] FIG. 2 is an exploded view of the secondary battery shown in FIG. 1 according to the embodiment of the present application. [Figure 3] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 4] 1 is a schematic diagram of a battery pack according to an embodiment of the present application; [Figure 5] FIG. 5 is an exploded view of the battery pack according to the embodiment of the present application shown in FIG. 4. [Figure 6] 1 is a schematic diagram of a power consumption device that uses a secondary battery as a power source according to an embodiment of the present application. [Figure 7] 1 is an SEM photograph of a first positive electrode active material produced in Production Example A10 of the present application. [Figure 8] 1 is an SEM photograph of a first positive electrode active material produced in Production Example A15 of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0035] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the present application's positive electrode active material and manufacturing method thereof, positive electrode plate, secondary battery, battery module, battery pack, and power consumption device will be described in detail. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of structures that are actually the same may be omitted. This is to avoid unnecessarily lengthening the following description and to facilitate understanding by those skilled in the art. Note that the 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 described in the claims.

[0036] The "ranges" disclosed in this application are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the end values, and any combination is possible; i.e., any lower limit can be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also possible. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all possible. In this application, unless otherwise specified, a numerical range "a to b" is a shorthand notation for any combination of real numbers a to b, where a and b are both real numbers. For example, the numerical range "0-5" represents that the present specification has already listed all real numbers between "0-5," and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0037] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0038] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0039] Unless otherwise stated, all steps in this application may be performed in order or randomly, preferably in order. For example, a method including steps (a) and (b) means that the method may include steps (a) and (b) performed in order, or may include steps (b) and (a) performed in order. For example, a method that may further include step (c) means that step (c) may be added to the method in any order, e.g., the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0040] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open-ended or closed-ended. For example, "comprise" and "comprises" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[0041] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0042] [Secondary battery] A secondary battery is also called a rechargeable battery or storage battery, and is a battery that can be continuously used by activating the active material through charging after the battery is discharged.

[0043] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. During charging and discharging of the battery, active ions (e.g., lithium ions) are absorbed and released by moving back and forth between the positive electrode plate and the negative electrode plate. The separator, located between the positive electrode plate and the negative electrode plate, primarily serves to prevent short-circuiting between the positive and negative electrodes and allows the active ions to pass through. The electrolyte primarily serves to conduct the active ions between the positive and negative electrode plates.

[0044] [Cathode active material] One embodiment of the present application provides a cathode active material, the cathode active material including a first cathode active material and a second cathode active material, wherein: The first positive electrode active material is the compound LiNi b Co d Mn e M f O2, wherein b is selected from the range of 0.314 to 0.970, optionally selected from the range of 0.65 to 0.97; d is selected from the range of 0 to 0.320, optionally selected from the range of 0.047 to 0.320 or selected from the range of 0.005 to 0.188; e is selected from the range of 0.006 to 0.390, optionally selected from the range of 0.006 to 0.102; the sum of b, d, e and f is 1 and f is greater than 0; M is one or more elements selected from Mn, Al, Mg, Ca, Na, Ti, W, Zr, Sr, Cr, Zn, Ba, B, S and Y; The second positive electrode active material is the compound Li a A x Mn 1-y B y P 1-z C z O 4-n D nwherein a is selected from the range of 0.9 to 1.1, x is selected from the range of 0.001 to 0.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, n is selected from the range of 0.001 to 0.1, A is one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W, and optionally Mg and / or Mo, B is one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and optionally one or more elements selected from V, Fe and Co, C is one or more elements selected from B (boron), S, Si and N, and optionally one or more elements selected from S, Si and N, and D is one or more elements selected from S, F, Cl and Br, and optionally F.

[0045] The first cathode active material is a layered transition metal oxide with two-dimensional lithium ion transport channels, while the second cathode active material has only one-dimensional lithium ion transport channels. By combining the two materials and complementing their advantages, the overall electrochemical performance can be improved. The initial charge-discharge efficiency of the first cathode active material is generally lower than that of the second cathode active material. By combining the two materials, the secondary battery contains a large amount of reversible lithium ions even after the chemical-based anode film is formed and consumed, improving the cycle capacity retention rate of the secondary battery, extending the cycle life of the secondary battery, and improving the safety of the secondary battery.

[0046] Although the mechanism is not yet clear, the present inventors have unexpectedly discovered that the second cathode active material of the present application is obtained by doping element(s) into the compound LiMnPO4, where A, B, C, and D are elements doped into the Li site, Mn site, P site, and O site of the compound LiMnPO4, respectively. Without being bound by theory, the present inventors have discovered that the improved performance of lithium manganese phosphate is related to the decrease in the lattice change rate and the decrease in surface activity of lithium manganese phosphate during lithium release. The decrease in lattice change rate reduces the lattice constant difference between the grain boundaries between the two phases, reducing interfacial stress and increasing the Li +This can enhance the interfacial transport capability of the cathode active material, thereby improving its rate performance. On the other hand, high surface activity can lead to severe interfacial side reactions, exacerbating gas generation, electrolyte consumption, and interfacial breakdown, thereby affecting performance such as cycling of secondary batteries. In this application, doping at the Li and Mn sites reduces the lattice change rate. Doping at the Mn site further reduces surface activity, thereby suppressing Mn dissolution and interfacial side reactions between the cathode active material and the electrolyte. Doping at the P site accelerates the rate of change of the Mn-O bond length and reduces the small polariton transition barrier of the material, thereby benefiting electronic conductivity. Doping at the O site also has a positive effect on reducing interfacial side reactions. Doping at the P and O sites further affects Mn dissolution and kinetic performance of antisite defects. Therefore, doping reduces the concentration of antisite defects in the material, improving the kinetic performance and gram capacity of the material, and can also change the particle topography, thereby increasing the compaction density. The present applicant has unexpectedly discovered that by simultaneously doping specific elements in specific amounts into the Li, Mn, P and O sites of the compound LiMnPO4, it is possible to obtain significantly improved rate performance, significantly reduce the leaching of Mn and the elements doped into the Mn site, and obtain significantly improved cycle performance and / or high temperature stability, as well as improve the gram capacity and compacted density of the material.

[0047] In some embodiments, M is Mg and / or Al. Doping the first positive electrode active material with Al can increase the structural and thermal stability of the material and improve its cycling performance. Doping the first positive electrode active material with Mg increases or decreases the valence of the transition metal ions, thereby generating holes or electrons, changing the band structure of the material, improving the intrinsic electronic conductivity of the material, and improving the cycling performance of secondary batteries. Co-doping Mg and Al into the lattice of the bulk material can synergistically stabilize the material structure, improve the miscibility of the material cations, suppress oxygen precipitation, and further improve the cycling performance and thermal stability of secondary batteries.

[0048] Unless otherwise noted, the chemical formula is Li a A x Mn 1-y B y P 1-z C z O 4-n D n In the above, when A is two or more elements, the above-mentioned limit on the numerical range of x not only limits the stoichiometric number for each type of element that makes up A, but also limits the sum of the stoichiometric numbers of each element that makes up A. For example, when A is two or more elements A1, A2...An, the stoichiometric numbers x1, x2...xn of A1, A2...An must each fall within the numerical range in which x is limited by this application, and the sum of x1, x2...xn must also fall within this numerical range. Similarly, when B, C, and D are two or more elements, the limit on the numerical range of the stoichiometric numbers of B, C, and D in this application also has the above meaning. Similarly, a compound of the chemical formula LiNi b Co d Mn e M f When M in O2 is two or more elements, the numerical range limitations of the stoichiometric number of M in this application also have the above meanings.

[0049] In some embodiments, the compound LiNi b Co d Mn e M f O2 and Li a A x Mn 1-y B y P 1-z C z O 4-n D n Both maintain electroneutrality.

[0050] In some embodiments, the mass of the first positive electrode active material is m1, the mass of the second positive electrode active material is m2, and the value of m1 / (m1+m2) is 2% to 55%, and optionally 3% to 50%, such that the mass percentage of the first positive electrode active material in the two positive electrode active materials is within the above range, thereby improving the stability and safety of the entire positive electrode active material.

[0051] In some embodiments, the value of b×m1 / (m1+m2) is 0.017 to 0.457, and optionally 0.025 to 0.415, thereby further improving the stability and safety of the entire positive electrode active material.

[0052] In some embodiments, the first active cathode material is a single crystal or pseudo-single crystal material, and the particle size D of the first active cathode material is v 50 is 5.8 μm or less, optionally 2.3 to 5.8 μm, and more optionally 2.3 to 4.3 μm.

[0053] By setting the particle size of the single crystal or pseudo-single crystal first positive electrode active material within the above range, the electrochemical reaction area can be optimized, and the interfacial side reactions of the positive electrode during secondary battery cycling can be further reduced and suppressed, thereby reducing the cycle decay rate of the secondary battery and extending the cycle life of the secondary battery.

[0054] In some embodiments, the first active cathode material is a single crystal or pseudo-single crystal material, and the first active cathode material has a BET specific surface area of ​​1.15 m 2 / g or less, and selectively 0.45 to 1.15m 2 / g, and / or The compaction density of the first positive electrode active material at a pressure of 3 T is 3.11 g / cm 3 or more, and selectively 3.11 to 3.4 g / cm 3 is.

[0055] In some embodiments, when the first active cathode material is a single crystalline or pseudo-single crystalline material, d is selected from the range of 0.05 to 0.320, optionally selected from the range of 0.05 to 0.282, and / or b is greater than 0.314 and less than 0.97, and is selectively selected within the range of 0.55 to 0.869.

[0056] When the first positive electrode active material is a single crystal or pseudo-single crystal material, having d and b within the above ranges is advantageous for further improving the conductivity and rate performance of the positive electrode active material, further improving the cycle capacity retention rate of the secondary battery, and further extending the cycle life of the secondary battery.

[0057] In some embodiments, when the first active cathode material is a polycrystalline material, the particle size D of the first active cathode material v 50 is 3.5 to 13.5 μm, and / or The BET specific surface area of ​​the first positive electrode active material is 1.32 m 2 / g or less, and selectively 0.28~1.32m 2 / g, and / or The compaction density of the first positive electrode active material at a pressure of 3 T is 2.92 g / cm 3 or more, and selectively 2.92 to 3.31 g / cm 3 is.

[0058] By setting the particle size, specific surface area and compaction density of the polycrystalline first positive electrode active material within the above ranges, the rate performance of the positive electrode active material can be further improved, the interfacial side reactions of the positive electrode during secondary battery cycling can be further reduced and suppressed, the cycle decay rate of the secondary battery can be reduced, and the cycle life of the secondary battery can be extended.

[0059] In some embodiments, the first active cathode material further comprises lithium carbonate and / or lithium hydroxide; Optionally, based on the mass of the first positive electrode active material, the mass content of lithium carbonate is 1% or less and / or the mass content of lithium hydroxide is 1% or less.

[0060] Residual water molecules trapped in the second positive electrode active material may react with the electrolyte to generate HF, which is likely to cause damage to the positive electrode active material itself or the SEI film on the negative electrode plate, further affecting the life of the secondary battery. The lithium carbonate and / or lithium hydroxide further contained in the first positive electrode active material of the present application can undergo a neutralization reaction with HF, reducing or suppressing the damage caused by HF to the positive electrode active material or the SEI film on the negative electrode plate, thereby further improving the cycle life of the secondary battery.

[0061] In some embodiments, in the second positive electrode active material, A is any one element selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B is at least two elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C is any one element selected from B (boron), S, Si, and N; and D is any one element selected from S, F, Cl, and Br; Optionally, A is Mg or Nb, and / or B is at least two elements selected from Fe, Ti, V, Co and Mg, and optionally Fe and one or more elements selected from Ti, V, Co and Mg; and / or C is S, and / or D is F.

[0062] By selecting an element doped at the Li site within the above range, the lattice change rate during lithium release can be further reduced, thereby further improving the rate performance of the secondary battery. By selecting an element doped at the Mn site within the above range, the electronic conductivity can be further improved and the lattice change rate can be further reduced, thereby increasing the rate performance and gram capacity of the secondary battery. By selecting an element doped at the P site within the above range, the rate performance of the secondary battery can be further improved. By selecting an element doped at the O site within the above range, the interfacial side reactions can be further reduced and the high-temperature performance of the secondary battery can be improved.

[0063] In some embodiments, in the second positive electrode active material, x is selected from the range of 0.001 to 0.005, and / or y is selected from the range of 0.01 to 0.5, optionally selected from the range of 0.25 to 0.5, and / or z is selected from the range of 0.001 to 0.005, and / or n is selected from the range of 0.001 to 0.005.

[0064] By selecting a y value within the above range, the gram capacity and rate performance of the material can be further improved. By selecting an x ​​value within the above range, the kinetic performance of the material can be further improved. By selecting a z value within the above range, the rate performance of the secondary battery can be further improved. By selecting an n value within the above range, the high temperature performance of the secondary battery can be further improved.

[0065] In some embodiments, the value of (1-y):y is selected from the range of 1 to 4, and optionally from the range of 1.5 to 3, and the value of a:x is selected from the range of 9 to 1100, and optionally from the range of 190 to 998. This can further increase the energy density and cycle performance of the positive electrode active material.

[0066] In some embodiments, the lattice change rate of the second positive electrode active material before and after complete lithium release is 8% or less, and optionally 4% or less. Reducing the lattice change rate can facilitate Li-ion transport, i.e., the Li-ion transfer ability in the material is strengthened, which is advantageous for improving the rate performance of the secondary battery. The lattice change rate can be measured by methods known in the art, such as X-ray diffraction spectroscopy (XRD).

[0067] In some embodiments, the second positive electrode active material has a Li / Mn antisite defect concentration of 2% or less, and optionally 0.5% or less. Li / Mn antisite defects are LiMnPO4 lattice defects. + and Mn 2+ The Li / Mn antisite defect concentration is the concentration of Mn in the positive electrode active material. 2+ Replaced by Li + Li + The percentage of the total amount. Antisite defects Mn 2+ Li + This is advantageous in improving the gram capacity and rate performance of the positive electrode active material by inhibiting the transfer of Li and reducing the concentration of Li / Mn antisite defects. The concentration of Li / Mn antisite defects can be measured by methods known in the art, such as XRD.

[0068] In some embodiments, the surface oxygen valence of the second positive electrode active material is −1.82 or less, and optionally −1.89 to −1.98. Reducing the surface oxygen valence can reduce interfacial side reactions between the positive electrode active material and the electrolyte, thereby improving the cycling performance and high-temperature stability of the secondary battery. The surface oxygen valence can be measured by methods known in the art, such as electron energy loss spectroscopy (EELS).

[0069] In some embodiments, the second positive electrode active material has a packed density at 3 T of 2.0 g / cm 3 or more, and optionally 2.2 g / cm 3 That's all. The higher the compaction density, the greater the weight of active material per unit volume, so improving the compaction density is advantageous for improving the volumetric energy density of the cell. Compaction density can be measured in accordance with GB / T 24533-2009.

[0070] In some embodiments, the second active cathode material further comprises carbon, wherein the carbon is a compound Li a A x Mn 1-y B y P1-z C z O 4-n D n This can improve the conductivity of the positive electrode active material.

[0071] In some embodiments, b may be, for example, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

[0072] In some embodiments, d may be, for example, 0.05, 0.1, 0.15, 0.2, 0.25, or 0.3.

[0073] In some embodiments, e may be, for example, 0.01, 0.02, 0.05, 0.1, 0.15, 0.2, 0.26, 0.3, or 0.35.

[0074] [Method for producing positive electrode active material] One embodiment of the present application provides a method for producing a cathode active material, the method comprising: providing a first active cathode material and a second active cathode material; mixing the first positive electrode active material with the second positive electrode active material; The first positive electrode active material is the compound LiNi b Co d Mn e M f O2, and the second positive electrode active material is the compound Li a A x Mn 1-y B y P 1-z C z O 4-n D n wherein a, b, d, e, f, x, y, z, n, M, A, B, C, and D are defined as described in [Positive Electrode Active Material], Optionally, the first positive electrode active material further includes lithium carbonate and / or lithium hydroxide; Optionally, the second positive electrode active material is the compound Li a A x Mn 1-y B y P1-z C z O 4-n D n The carbon is further coated on the surface of the substrate.

[0075] As a result, the present application uses a mixture of a first positive electrode active material and a second positive electrode active material to complement the advantages of the two materials, improve the cycle capacity retention rate of the secondary battery, extend the cycle life of the secondary battery, and improve the safety of the secondary battery.

[0076] In some embodiments, the first positive electrode active material is prepared by the following steps. Step 1): Ni salt, Co salt, Mn salt and alkali are reacted in a solvent, followed by solid-liquid separation and collection of the solid phase. Step 2): Mixing the solid phase material, the lithium source, and the source of element M, ball milling, sintering, and cooling to obtain a first positive electrode active material. Optionally, in step 2), the cooled first positive electrode active material is crushed and sieved, or the cooled first positive electrode active material is crushed, re-sintered, crushed, and sieved.

[0077] In some embodiments, in step 1), the reaction is carried out under conditions of a pH value of 9-13, and optionally under conditions of a pH value of 9-12 or 10-13.

[0078] In some embodiments, in step 1), the reaction temperature is between 40°C and 80°C, for example, 50°C, 55°C, 60°C.

[0079] In some embodiments, in step 1), the reaction time is 8 to 70 hours, for example, 20 hours, 55 hours, 60 hours, or 65 hours.

[0080] In some embodiments, in step 1), the reaction is carried out at a rotation speed of 150 to 1000 r / min, for example, 300 r / min or 500 r / min.

[0081] In some embodiments, in step 1), the solid-liquid separation is filtration.

[0082] In some embodiments, prior to step 2), the solid phase material is washed, dried, and optionally vacuum dried at 100° C.-140° C. for 12-48 hours, for example, at 120° C. for 24 hours.

[0083] In some embodiments, in step 2), the rotation speed of the ball mill is 200-500 r / s, for example, 300 r / s, 500 r / s.

[0084] In some embodiments, in step 2), the ball milling time is 1-5 hours, for example, 2, 3, or 4 hours.

[0085] In some embodiments, step 2) is sintered in an air atmosphere, optionally at 0.1 to 0.4 MPa.

[0086] In some embodiments, in step 2), the sintering procedure is to heat the material to 750°C-950°C and hold for 12-20 hours for pre-sintering, with a heating rate of 1°C / min, and optionally, cool the material to 600°C at the same rate and hold for 8 hours for sintering, and then cool the material to 300°C at a rate of 1°C / min after sintering.

[0087] In some embodiments, in step 2), the re-sintering procedure is to heat the material to 400°C at a rate of 20°C / min, hold the temperature for 20 hours, and then cool it to 300°C at a rate of 1°C / min after sintering.

[0088] In some embodiments, in step 2), the pulverization is performed using an airflow pulverizer, and optionally the rotation speed of the airflow pulverizer is 2500-3500 r / min, for example 3000 r / min, and optionally the air volume of the airflow pulverizer is 400-600 m 3 / h, e.g. 500m 3 / h.

[0089] In some embodiments, step 2) involves sieving through a 450-550 mesh (eg, 500 mesh) screen.

[0090] In some embodiments, the second positive electrode active material is prepared by the following steps. Step (1): A manganese source, a source of element B, an acid, and a selective solvent are mixed to obtain a mixture. Step (2): Mixing the mixture with a lithium source, a phosphorus source, a source of element A, a source of element C, a source of element D, an optional carbon source, and an optional solvent, drying, and sintering to obtain Li m A x Mn 1-y B y P 1-z C z O 4-n D n A core material containing the following is obtained. The definitions of A to D are as described above.

[0091] In some embodiments, step (1) is carried out at 60°C to 120°C, optionally 70°C to 120°C (e.g., about 60°C, about 70°C, about 80°C, about 90°C, about 100°C, about 110°C, or about 120°C), and / or, in step (1), the mixture is stirred and mixed at a rotation speed of 200 to 800 rpm (e.g., 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, or 800 rpm), optionally for 1 to 9 hours (further optionally for 3 to 7 hours, e.g., about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6 hours, about 7 hours, about 8 hours, or about 9 hours).

[0092] In some embodiments, in step (2), the mixing is carried out for 8 to 15 hours (e.g., about 8 hours, about 9 hours, about 10 hours, about 11 hours, about 12 hours, about 13 hours, about 14 hours, or about 15 hours), optionally at a temperature of 20 to 120°C, optionally at a temperature of 40 to 120°C (e.g., about 30°C, about 50°C, about 60°C, about 70°C, about 80°C, about 90°C, about 100°C, about 110°C, or about 120°C).

[0093] When the temperature and time during the preparation process are within the above ranges, the resulting second positive electrode active material has relatively few lattice defects, which is advantageous in inhibiting manganese leaching and reducing interfacial side reactions between the positive electrode active material and the electrolyte, thereby improving the cycle performance and safety performance of the secondary battery.

[0094] In some embodiments, in step (2), the mixing is performed under a condition of pH 3.5 to 6, optionally pH 4 to 6, and more optionally pH 4 to 5. It should be noted that in the present application, the pH may be adjusted by a method commonly used in the art, for example, by adding an acid or alkali.

[0095] In some embodiments, optionally in step (2), the molar ratio of the mixture or manganese salt particles doped with element B to the lithium source to the phosphorus source is 1:0.4-2.1:0.1-2.1, and optionally about 1:0.4-0.5:0.1-1.

[0096] In some embodiments, in step (2), sintering is performed at 600 to 900°C for 4 to 10 hours. Optionally, sintering may be performed at about 650°C, about 700°C, about 750°C, about 800°C, about 850°C, or about 900°C for about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, or about 10 hours. Optionally, sintering is performed under a protective atmosphere of an inert gas or a mixed atmosphere of an inert gas and hydrogen gas. More optionally, the protective atmosphere is a mixed atmosphere of 70 to 90% by volume of nitrogen gas and 10 to 30% by volume of hydrogen gas. The sintering temperature and sintering time may be within any range of the above values. This improves crystallinity, reduces the formation of heterophases, and maintains a consistent particle size, thereby improving the gram capacity and compaction density of the positive electrode active material and improving the overall performance of the secondary battery, including rate capability.

[0097] In some alternative embodiments, the mixture obtained in step (1) is filtered, dried, and ground to form a powder of particle size D vManganese salt particles having a particle size of 50 to 200 nm are obtained. The manganese salt particles doped with element B are used in step (2) to mix with a lithium source, a phosphorus source, a source of element A, a source of element C, a source of element D, and a selective solvent.

[0098] In some alternative embodiments, step (2) involves drying by spray drying equipment.

[0099] In some alternative embodiments, in step (2), grinding is performed simultaneously with mixing.

[0100] The manufacturing method of the present application is not particularly limited to the origin of the material, and the origin of a certain element may include one or more of the element's simple substance, sulfate, halide, nitrate, phosphate, oxalate, carbonate, oxide, and hydroxide, provided that the origin can achieve the purpose of the manufacturing method of the present application.

[0101] In some embodiments, the source of element A is one or more selected from the group consisting of an element, an oxide, a phosphate, an oxalate, a carbonate, and a sulfate of element A; and / or the source of element B is one or more selected from the group consisting of element B, oxide, phosphate, oxalate, carbonate and sulfate; and / or the source of element C is one or more selected from sulfates, borates, nitrates and silicates of element C; and / or The source of element D is one or more selected from a simple substance of element D and an ammonium salt thereof.

[0102] In some embodiments, the source of element M is one or more selected from element M itself, carbonates, sulfates, halides, nitrates, organic acid salts, oxides, and hydroxides.

[0103] The amount of each of the sources of elements A, B, C, D, and M added depends on the target doping amount, and the ratio of the amount of the lithium source, manganese source, and phosphorus source used is in accordance with the stoichiometric ratio.

[0104] In the present application, the manganese source may be any manganese-containing material known in the art that can be used to prepare lithium manganese phosphate. By way of example, the manganese source may be one or more selected from elemental manganese, manganese dioxide, manganese phosphate, manganese oxalate, and manganese carbonate.

[0105] In the present application, the acid may be one or more selected from hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, organic acids such as silicic acid, metasilicic acid, and organic acids such as oxalic acid. In some embodiments, the acid is a dilute organic acid having a concentration of 60% by weight or less.

[0106] In the present application, the lithium source may be any lithium-containing material known in the art that can be used to prepare lithium manganese phosphate. For example, the lithium source may be one or more selected from lithium carbonate, lithium hydroxide, lithium phosphate, and lithium dihydrogen phosphate.

[0107] In the present application, the phosphorus source may be any phosphorus-containing material known in the art that can be used to prepare lithium manganese phosphate. For example, the phosphorus source may be one or more selected from diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, and phosphoric acid.

[0108] In the present application, by way of example, the carbon source is one or more selected from starch, sucrose, glucose, polyvinyl alcohol, polyethylene glycol, citric acid.

[0109] [Positive electrode plate] The positive electrode plate 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, and the positive electrode film layer includes the above-described positive electrode active material or a positive electrode active material produced by the above-described method.

[0110] For example, the positive electrode current collector has two surfaces that face each other in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on either one or both of the two facing surfaces of the positive electrode current collector.

[0111] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0112] In some embodiments, the positive electrode membrane layer optionally further comprises an adhesive. For example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0113] In some embodiments, the positive electrode film layer optionally further comprises a conductive agent, for example, the conductive agent may comprise at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0114] In some embodiments, a positive electrode plate can be manufactured as follows: Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then coated onto a positive electrode current collector, and the positive electrode plate is obtained after processes such as drying and cold pressing.

[0115] [Negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0116] For example, the negative electrode current collector has two surfaces that face each other in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two facing surfaces of the negative electrode current collector.

[0117] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, the metal foil sheet may be copper foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0118] In some embodiments, the negative electrode active material may be any negative electrode active material known in the art for use in batteries. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicone-based material, a tin-based material, and lithium titanate. The silicone-based material may be selected from at least one of a silicone element, a silicone oxide, a silicone carbon composite, a silicone nitrogen composite, and a silicone alloy. The tin-based material may be selected from at least one of a tin element, a tin oxide, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials usable as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination.

[0119] In some embodiments, the negative electrode membrane layer optionally further comprises an adhesive, for example, the adhesive may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0120] In some embodiments, the negative electrode film layer optionally further comprises a conductive agent, for example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0121] In some embodiments, the negative electrode membrane layer optionally further comprises other additives, such as a thickener (eg, carboxymethylcellulose sodium (CMC-Na)).

[0122] In some embodiments, the negative electrode plate can be manufactured in the following manner: Components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then coated onto a negative electrode current collector, and the negative electrode plate is obtained after processes such as drying and cold pressing.

[0123] [Electrolyte] The electrolyte serves to conduct ions between the positive and negative electrodes. The present application does not specifically limit the type of electrolyte, and it can be selected according to needs. For example, the electrolyte may be liquid, gel, or all solid.

[0124] In some embodiments, the electrolyte is liquid and includes an electrolyte salt and a solvent. In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0125] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl 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, ethyl methyl sulfone, and diethyl sulfone.

[0126] In some embodiments, the electrolyte solution optionally further contains 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, or an additive that improves the high-temperature or low-temperature performance of the battery.

[0127] [Separator] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous separator with good chemical stability and mechanical stability may be selected.

[0128] In some embodiments, the separator may be made of at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without any particular limitation.

[0129] In some embodiments, the positive and negative electrodes and the separator can be fabricated into an electrode assembly by a winding or lamination process.

[0130] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and electrolyte.

[0131] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0132] The present application does not particularly limit the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows an example of a rectangular secondary battery 5.

[0133] In some embodiments, referring to FIG. 2 , the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, which together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged within the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art can select the number according to actual needs.

[0134] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, with the specific number being selectable by those skilled in the art depending on the application and capacity of the battery module.

[0135] Fig. 3 shows an example of a battery module 4. Referring to Fig. 3, in the battery module 4, a plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.

[0136] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in this accommodating space.

[0137] In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, the specific number of which can be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0138] 4 and 5 show an example of a battery pack 1. Referring to FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 covers the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0139] The present application also provides a power consuming device, the power consuming device including at least one of a secondary battery, a battery module, or a battery pack according to the present application. The secondary battery, the battery module, or the battery pack may be used 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, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0140] The power consumption device can be selected from a secondary battery, a battery module, or a battery pack depending on its usage needs.

[0141] 6 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high power output and high energy density of the secondary battery of the power consuming device, a battery pack or battery module can be employed.

[0142] [Example] The following examples of the present application are described. The examples described below are illustrative and are used only to interpret the present application and should not be understood as limitations on the present application. If specific techniques or conditions are not specified in the examples, they will be carried out according to the techniques or conditions described in literature in the field or according to the product specifications. If the manufacturer of the reagents or equipment used is not specified, they are all ordinary products that are commercially available.

[0143] Production of first positive electrode active material [Manufacturing example A3]:LiNi 0.55 Co 0.113 Mn 0.277 Al 0.04 Mg 0.02 O2 (single crystal-like) (1) A mixed solution was prepared by adding water to NiSO4, CoSO4, and MnSO4 in a molar ratio of 0.55:0.113:0.277. The concentration of NiSO4 in the mixed solution was 2 mol / L, and a 5 mol / L NaOH solution was prepared. (2) 50L of the mixed solution was introduced into the reaction vessel, and then 50L of NaOH solution and an appropriate amount of 0.5mol / L of aqueous ammonia solution were introduced into the reaction vessel. The pH value in the reaction vessel was set to 9.0-12.0, the reaction temperature was set to 40℃-80℃, and the reaction was carried out under stirring conditions for 60 hours. The stirring rotation speed was set to 300-1000r / min. After completion, the precipitate was filtered and washed, and the washed precipitate was vacuum dried at 120℃ for 24 hours to obtain the precursor. (3) Li2CO3, precursor, Al2O3, and MgO were mixed. The molar ratio of Li2CO3 (in terms of the molar amount of Li), precursor (in terms of the total molar amount of Ni, Co, and Mn in the mixed solution), Al2O3 (in terms of the molar amount of Al), and MgO was 1.05:0.94:0.04:0.02. After mixing, the mixture was placed in a ball mill and ball milled at a rotation speed of 300 r / s for 2 hours. It was then placed in a van furnace and pre-sintered in an air atmosphere at 0.2 MPa by heating to 950°C and holding for 12 hours. The heating rate was 1°C / min. The temperature was then lowered to 600°C at a rate of 1°C / min and held for 8 hours for sintering. After sintering, the temperature was lowered to 300°C at a rate of 1°C / min and then naturally cooled to room temperature. It was then passed through an airflow mill and sintered at a rotation speed of 3000 r / min for 500 m / s. 3 / h, crushed for 0.5 hours, and sieved through a 500 mesh screen to obtain a first positive electrode active material.

[0144] [Manufacturing example A16]:LiNi 0.83 Co 0.114 Mn 0.006 Al 0.04 Mg 0.01 O2 (polycrystalline) (1) A mixed solution was prepared by adding water to NiSO4, CoSO4, and MnSO4 in a molar ratio of 0.83:0.114:0.006. The concentration of NiSO4 in the mixed solution was 2 mol / L, and a 6 mol / L NaOH solution was prepared. (2) 50L of the mixed solution was introduced into the reaction vessel, and then 50L of NaOH solution and an appropriate amount of 0.5mol / L aqueous ammonia solution were introduced into the reaction vessel. The pH value in the reaction vessel was set to 10-13, the reaction temperature was set to 40℃-80℃, and the reaction was carried out under stirring conditions for 8-20 hours, with the stirring rotation speed set to 150-300r / min. After completion, the precipitate was filtered and washed, and the washed precipitate was vacuum dried at 120℃ for 24 hours to obtain the precursor. (3) LiOH, precursor, Al2O3, and MgO were mixed. The molar ratio of LiOH, precursor (calculated as the total molar amount of the three elements Ni, Co, and Mn in the mixed solution), Al2O3 (calculated as the molar amount of Al element), and MgO was 1.05:0.95:0.04:0.01. After mixing, the mixture was placed in a ball mill and ball milled at a rotation speed of 500 r / s for 2 hours. It was then placed in a van furnace and pre-sintered by heating to 750°C in an air atmosphere at 0.2 MPa and maintaining the temperature for 20 hours. The heating rate was 20°C / min. After sintering, the temperature was lowered to 300°C at a rate of 1°C / min, then naturally cooled to room temperature, and crushed at a rotation speed of 2000 r / min for 5 hours. The mixture was then heated to 400°C at a rate of 20°C / min and kept at that temperature for 20 hours before sintering. After sintering, the temperature was lowered to 300°C at a rate of 1°C / min, then naturally cooled to room temperature, and then passed through an airflow crusher at a rotation speed of 3000 r / min for 500 m. 3 / h, crushed for 0.5 hours, and then sieved through a 400 mesh screen to obtain a first positive electrode active material.

[0145] [Production Examples A1, A2, A4 to A15, A17 to A22 and Comparative Production Example A1] The first positive electrode active materials of Preparation Examples A1, A2, A4 to A11, A22 and Comparative Preparation Example A1 were prepared in a manner similar to Preparation Example A3. The differences in the preparation are shown in Table 1, and the remaining procedures were the same as those of Preparation Example A3. Manufacturing Examples A12 to A15 and A17 to A21 were manufactured in a manner similar to Manufacturing Example A16, and differences in manufacturing are shown in Table 1, with the remaining being the same as Manufacturing Example A16.

[0146] [Table 1] JPEG0007780659000002.jpg173169 JPEG0007780659000003.jpg175169 JPEG0007780659000004.jpg154169

[0147] Production of second positive electrode active material [Manufacturing example B1] Preparation of doped manganese oxalate: 1.3 mol of MnSO4·H2O and 0.7 mol of FeSO4·H2O were mixed thoroughly in a blender for 6 hours. The mixture was transferred to a reactor, and 10 L of deionized water and 2 mol of oxalic acid dihydrate were added. The mixture was heated to 80°C. After stirring at 600 rpm for 6 hours, the reaction was completed (no bubbles were generated) and a suspension of Fe-doped manganese oxalate was obtained. The suspension was filtered, and the cake was dried at 120°C and crushed to a particle size of D. v Fe-doped manganese oxalate particles with sizes of approximately 50 to 100 nm were obtained. Preparation of doped manganese phosphate lithium: 1 mol Fe-doped manganese oxalate particles, 0.497 mol lithium carbonate, 0.001 mol Mo(SO4)3, 0.999 mol phosphate solution containing 85% phosphoric acid, 0.001 mol H4SiO4, 0.0005 mol NH4HF2, and 0.005 mol sucrose were added to 20 L of deionized water. The mixture was transferred to a sand mill and thoroughly ground and stirred for 10 hours to obtain a slurry. The slurry was then transferred to a spray dryer and granulated at 250°C for 4 hours. The particles were then sintered at 700°C for 10 hours in a nitrogen (90% v / v) + hydrogen (10% v / v) protective atmosphere to obtain the second cathode active material, carbon-coated Li. 0.994 Mo 0.001 Mn 0.65 Fe 0.35 P 0.999 Si 0.001 O 3.999 F 0.001 The element content of the positive electrode active material can be detected using inductively coupled plasma emission spectroscopy (ICP).

[0148] [Manufacturing example B2] This is the same as Preparation Example B1, except that the amount of high-purity Li2CO3 was changed to 0.4885 mol, Mo(SO4)3 was replaced with an equal molar amount of MgSO4, the amount of FeSO4·H2O was changed to 0.68 mol, an additional 0.02 mol of Ti(SO4)2 was added when preparing doped manganese oxalate, and H4SiO4 was replaced with an equal molar amount of HNO3.

[0149] [Manufacturing Example B3] The same as Production Example B1 except that the amount of high-purity Li2CO3 was changed to 0.496 mol, Mo(SO4)3 was replaced with an equimolar amount of W(SO4)3, and H4SiO4 was replaced with an equimolar amount of H2SO4.

[0150] [Manufacturing example B4] The procedure was the same as Preparation Example B1, except that the amount of high-purity Li2CO3 was changed to 0.4985 mol, 0.001 mol of Mo(SO4)3 was changed to 0.0005 mol of Al2(SO4)3, and NH4HF2 was changed to an equimolar amount of NH4HCl2.

[0151] [Manufacturing example B5] This procedure is the same as Preparation Example B1, except that 0.7 mol of FeSO4·H2O was changed to 0.69 mol, an additional 0.01 mol of VCl2 was added when preparing doped manganese oxalate, the amount of Li2CO3 was changed to 0.4965 mol, 0.001 mol of Mo(SO4)3 was changed to 0.0005 mol of Nb2(SO4)5, and H4SiO4 was changed to an equal molar amount of H2SO4.

[0152] [Manufacturing example B6] The amount of FeSO₄·H₂O was changed to 0.68 mol, 0.01 mol of VCl₂ and 0.01 mol of MgSO₄ were added when preparing doped manganese oxalate, the amount of Li₂CO₃ was changed to 0.4965 mol, 0.001 mol of Mo(SO₄)₃ was replaced with 0.0005 mol of Nb₂(SO₄)₅, and H₄SiO₄ was replaced with an equal molar amount of H₂SO₄. This was the same as Preparation Example B1.

[0153] [Manufacturing example B7] The same as Preparation Example B6 except that MgSO4 was replaced with an equimolar amount of CoSO4.

[0154] [Manufacturing example B8] The same as Preparation Example B6 except that MgSO4 was replaced with an equimolar amount of NiSO4.

[0155] [Manufacturing example B9] The amount of FeSO4·H2O was changed to 0.698 mol, 0.002 mol of Ti(SO4)2 was added when preparing doped manganese oxalate, the amount of Li2CO3 was changed to 0.4955 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.0005 mol of Nb2(SO4)5, H4SiO4 was replaced with an equal molar amount of H2SO4, and NH4HF2 was replaced with an equal molar amount of NH4HCl2, which was the same as Preparation Example B1.

[0156] [Manufacturing Example B10] The same as Preparation Example B1, except that the amount of FeSO₄·H₂O was changed to 0.68 mol, 0.01 mol of VCl₂ and 0.01 mol of MgSO₄ were added when preparing doped manganese oxalate, the amount of Li₂CO₃ was changed to 0.4975 mol, 0.001 mol of Mo(SO₄)₃ was replaced with 0.0005 mol of Nb₂(SO₄)₅, and NH₄HF₂ was replaced with an equal molar amount of NH₄HBr₂.

[0157] [Manufacturing example B11] This is the same as Preparation Example B1, except that the amount of FeSO₄·H₂O was changed to 0.69 mol, an additional 0.01 mol of VCl₂ was added when preparing doped manganese oxalate, the amount of Li₂CO₃ was changed to 0.499 mol, Mo(SO₄)₃ was replaced with an equimolar amount of MgSO₄, and NH₄HF₂ was replaced with an equimolar amount of NH₄HBr₂.

[0158] [Manufacturing example B12] The same as Preparation Example B1, except that the amount of MnSO4·H2O was changed to 1.36 mol, the amount of FeSO4·H2O was changed to 0.6 mol, an additional 0.04 mol of VCl2 was added when preparing doped manganese oxalate, the amount of Li2CO3 was changed to 0.4985 mol, Mo(SO4)3 was replaced with an equimolar amount of MgSO4, and H4SiO4 was replaced with an equimolar amount of HNO3.

[0159] [Manufacturing example B13] This was the same as Preparation B12, except that the amount of MnSO4·H2O was changed to 1.16 mol and the amount of FeSO4·H2O was changed to 0.8 mol.

[0160] [Manufacturing example B14] This is the same as Preparation B12, except that the amount of MnSO4·H2O was changed to 1.3 mol and the amount of VCl2 was changed to 0.1 mol.

[0161] [Manufacturing example B15] The same as Preparation Example B1, except that the amount of MnSO4·H2O was changed to 1.2 mol, an additional 0.1 mol of VCl2 was added when preparing doped manganese oxalate, the amount of Li2CO3 was changed to 0.494 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.005 mol of MgSO4, and H4SiO4 was replaced with an equal molar amount of H2SO4.

[0162] [Manufacturing example B16] The same as Preparation Example B1, except that the amount of MnSO4·H2O was changed to 1.2 mol, an additional 0.1 mol of VCl2 was added when preparing doped manganese oxalate, the amount of Li2CO3 was changed to 0.467 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.005 mol of MgSO4, 0.001 mol of H4SiO4 was replaced with 0.005 mol of H2SO4, and 1.175 mol of 85% phosphoric acid was replaced with 1.171 mol of 85% phosphoric acid.

[0163] [Manufacturing example B17] The same as Preparation Example B1, except that the amount of MnSO4·H2O was changed to 1.2 mol, an additional 0.1 mol of VCl2 was added when preparing doped manganese oxalate, the amount of Li2CO3 was changed to 0.492 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.005 mol of MgSO4, H4SiO4 was replaced with an equal molar amount of H2SO4, and 0.0005 mol of NH4HF2 was replaced with 0.0025 mol.

[0164] [Manufacturing example B18] The amount of FeSO4·H2O was changed to 0.5 mol, and when doped manganese oxalate was prepared, 0.1 mol of VCl2 and 0.1 mol of CoSO4 were added, the amount of Li2CO3 was changed to 0.492 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.005 mol of MgSO4, H4SiO4 was replaced with an equal molar amount of H2SO4, and 0.0005 mol of NH4HF2 was replaced with 0.0025 mol. This was the same as Preparation Example B1.

[0165] [Manufacturing example B19] This is the same as Preparation B18, except that the amount of FeSO4·H2O was changed to 0.4 mol and 0.1 mol of CoSO4 was changed to 0.2 mol.

[0166] [Manufacturing example B20] The same as Preparation Example B18 except that the amount of MnSO4·H2O was changed to 1.5 mol, the amount of FeSO4·H2O was changed to 0.1 mol, and the amount of CoSO4 was changed to 0.3 mol.

[0167] [Manufacturing example B21] The same as Preparation B18 except that 0.1 mol of CoSO4 was replaced with 0.1 mol of NiSO4.

[0168] [Manufacturing example B22] The procedure was the same as Preparation Example B18, except that the amount of MnSO4·H2O was changed to 1.5 mol, the amount of FeSO4·H2O was changed to 0.2 mol, and 0.1 mol of CoSO4 was replaced with 0.2 mol of NiSO4.

[0169] [Manufacturing example B23] The same as Preparation Example B18 except that the amount of MnSO4·H2O was changed to 1.4 mol, the amount of FeSO4·H2O was changed to 0.3 mol, and the amount of CoSO4 was changed to 0.2 mol.

[0170] [Production Example B24] The same as Preparation Example B1, except that 1.3 mol of MnSO4·H2O was changed to 1.2 mol, 0.7 mol of FeSO4·H2O was changed to 0.5 mol, 0.1 mol of VCl2 and 0.2 mol of CoSO4 were added when preparing doped manganese oxalate, the amount of Li2CO3 was changed to 0.497 mol, 0.001 mol of Mo(SO4)3 was changed to 0.005 mol of MgSO4, H4SiO4 was changed to an equal molar amount of H2SO4, and 0.0005 mol of NH4HF2 was changed to 0.0025 mol.

[0171] [Manufacturing example B25] The same as Preparation Example B18 except that the amount of MnSO4·H2O was changed to 1.0 mol, the amount of FeSO4·H2O was changed to 0.7 mol, and the amount of CoSO4 was changed to 0.2 mol.

[0172] [Manufacturing example B26] The same as Preparation Example B1, except that the amount of MnSO4·H2O was changed to 1.4 mol, the amount of FeSO4·H2O was changed to 0.3 mol, 0.1 mol of VCl2 and 0.2 mol of CoSO4 were added when preparing doped manganese oxalate, the amount of Li2CO3 was changed to 0.4825 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.005 mol of MgSO4, the amount of H4SiO4 was changed to 0.1 mol, the amount of phosphoric acid was changed to 0.9 mol, and the amount of NH4HF2 was changed to 0.04 mol.

[0173] [Manufacturing example B27] The same as Preparation Example B1, except that the amount of MnSO4·H2O was changed to 1.4 mol, the amount of FeSO4·H2O was changed to 0.3 mol, 0.1 mol of VCl2 and 0.2 mol of CoSO4 were added when preparing doped manganese oxalate, the amount of Li2CO3 was changed to 0.485 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.005 mol of MgSO4, the amount of H4SiO4 was changed to 0.08 mol, the amount of phosphoric acid was changed to 0.92 mol, and the amount of NH4HF2 was changed to 0.05 mol.

[0174] [Manufacturing example B28-B41] The positive electrode active material was produced in the same manner as in Production Example B1, but the stirring rotation speed, temperature, grinding and stirring time in a sand mill, sintering temperature and sintering time when producing the doped manganese oxalate were changed, as shown in Table 2 below.

[0175] [Table 2]

[0176] [Production Examples B42-B54] The positive electrode active material was prepared in the same manner as in Preparation Example B1, but the lithium source, manganese source, phosphorus source, and the doped sources of elements A, B, C, and D were changed, as shown in Table 3 below. The composition of the prepared positive electrode active material was the same as in Preparation Example B1, i.e., all Li 0.994 Mo 0.001 Mn 0.65 Fe 0.35 P 0.999 Si 0.001 O 3.999 F 0.001 is.

[0177] [Table 3]

[0178] [Manufacturing example B55] (1) Preparation of doped manganese oxalate 1.2 mol of MnSO4·H2O and 0.79 mol of FeSO4·H2O were mixed thoroughly in a blender for 6 hours, then the mixture was transferred to a reaction vessel, and 10 L of deionized water, 2 mol of oxalic acid dihydrate, and 0.01 mol of VCl2 were added and heated to 80°C. After stirring at a rotation speed of 600 rpm for 6 hours, the reaction was completed (no bubbles were generated) and a suspension of Fe-doped manganese oxalate was obtained. The suspension was filtered, and the cake was dried at 120°C and crushed to obtain a particle size D. v Fe-doped manganese oxalate particles with sizes of approximately 50 to 100 nm were obtained.

[0179] (2) Preparation of doped lithium manganese phosphate 1 mol Fe-doped manganese oxalate particles, 0.45 mol lithium carbonate, 0.05 mol MgSO4, 0.9 mol phosphate solution containing 85% phosphoric acid, 0.1 mol H4SiO4, 0.05 mol NH4HF2, and 0.005 mol sucrose were added to 20 L of deionized water. The mixture was transferred to a sand mill and thoroughly ground and stirred for 10 hours to obtain a slurry. The slurry was then transferred to a spray dryer and granulated. The drying temperature was set to 250°C and dried for 4 hours to obtain particles. The particles were then sintered at 700°C for 10 hours in a nitrogen gas (90% v / v) + hydrogen gas (10% v / v) protective atmosphere to obtain the cathode active material. The elemental content was detected using inductively coupled plasma emission spectroscopy (ICP), and the chemical formula was Li 0.9 Mg 0.05 Mn 0.6 Fe 0.395 V 0.005 P 0.9 Si 0.1 O 3.9 F 0.1 obtained.

[0180] [Manufacturing example B56] In step (2), the lithium carbonate was 0.55 mol, the MgSO4 was 0.001 mol, and the NH4HF2 was 0.001 mol. The same as in Production Example B55, 1.1 Mg 0.001 Mn 0.6 Fe 0.395V 0.005 P 0.9 Si 0.1 O 3.998 F 0.002 obtained.

[0181] [Manufacturing example B57] In step (2), the same procedure as in Preparation Example B55 was carried out except that the MgSO4 was 0.1 mol, the 85% phosphoric acid aqueous solution contained 0.95 mol of phosphoric acid, the H4SiO4 was 0.05 mol, and the NH4HF2 was 0.025 mol. 0.9 Mg 0.1 Mn 0.6 Fe 0.395 V 0.005 P 0.95 Si 0.05 O 3.95 F 0.05 obtained.

[0182] [Manufacturing example B58] The same as Preparation Example B55, except that in step (1), MnSO4·H2O was 1.998 mol, FeSO4·H2O was 0.002 mol, and VCl2 was not used, and in step (2), lithium carbonate was 0.475 mol, the 85% phosphoric acid aqueous solution contained 0.96 mol of phosphoric acid, H4SiO4 was 0.04 mol, and NH4HF2 was 0.01 mol, and the positive electrode active material Li 0.95 Mg 0.05 Mn 0.999 Fe 0.001 P 0.96 Si 0.04 O 3.99 F 0.01 obtained.

[0183] [Production Example B59] The same as in Preparation Example B55, except that in step (1) MnSO4·H2O was 1.98 mol, FeSO4·H2O was 0.02 mol, and VCl2 was not used, and in step (2) lithium carbonate was 0.475 mol, the 85% phosphoric acid aqueous solution contained 0.96 mol phosphoric acid, H4SiO4 was 0.04 mol, and NH4HF2 was 0.01 mol, and the positive electrode active material Li0.95 Mg 0.05 Mn 0.99 Fe 0.01 P 0.96 Si 0.04 O 3.99 F 0.01 obtained.

[0184] [Manufacturing example B60] The same as Preparation Example B55, except that in step (1), MnSO4·H2O was 1.6 mol, FeSO4·H2O was 0.4 mol, and VCl2 was not used, and in step (2), lithium carbonate was 0.475 mol, the 85% phosphoric acid aqueous solution contained 0.96 mol of phosphoric acid, H4SiO4 was 0.04 mol, and NH4HF2 was 0.01 mol, and the positive electrode active material Li 0.95 Mg 0.05 Mn 0.8 Fe 0.2 P 0.96 Si 0.04 O 3.99 F 0.01 obtained.

[0185] [Comparative manufacturing example B1] Preparation of manganese oxalate: 1 mol of MnSO4·H2O was added to a reaction vessel, and 10 L of deionized water and 1 mol of oxalic acid dihydrate (equivalent to oxalic acid) were added. The reaction vessel was heated to 80°C and stirred at 600 rpm for 6 hours. The reaction was completed (no bubbles were generated) and a manganese oxalate suspension was obtained. The suspension was then filtered, and the cake was dried at 120°C and then crushed to obtain a median particle size D v Manganese oxalate particles with sizes of 50-200 nm were obtained.

[0186] Preparation of lithium manganese phosphate: 1 mol of the above manganese oxalate particles, 0.5 mol of lithium carbonate, 1 mol of phosphoric acid in an 85% aqueous solution, and 0.005 mol of sucrose were added to 20 L of deionized water. The mixture was transferred to a sand mill and thoroughly ground and stirred for 10 hours to obtain a slurry. The slurry was then transferred to a spray dryer and spray-dried and granulated. The drying temperature was set to 250°C and the mixture was dried for 4 hours to obtain particles. The powder was sintered at 700°C for 10 hours in a protective atmosphere of nitrogen gas (90% by volume) and hydrogen gas (10% by volume) to obtain carbon-coated LiMnPO4.

[0187] [Comparative manufacturing example B2] Comparative Example 1 was the same as Comparative Preparation Example B1, except that 1 mol of MnSO4·H2O was replaced with 0.85 mol of MnSO4·H2O and 0.15 mol of FeSO4·H2O, which were then added to a blender and thoroughly mixed for 6 hours before being added back to the reactor.

[0188] [Comparative manufacturing example B3] The same as Preparation Example B1 except that the amount of MnSO4·H2O was changed to 1.9 mol, 0.7 mol of FeSO4·H2O was replaced with 0.1 mol of ZnSO4, the amount of Li2CO3 was changed to 0.495 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.005 mol of MgSO4, the amount of phosphoric acid was changed to 1 mol, and H4SiO4 and NH4HF2 were not added.

[0189] [Comparative manufacturing example B4] The same as Preparation Example B1 except that the amount of MnSO4·H2O was changed to 1.2 mol, the amount of FeSO4·H2O to 0.8 mol, the amount of Li2CO3 to 0.45 mol, 0.001 mol of Mo(SO4)3 to 0.005 mol of Nb2(SO4)5, 0.999 mol of phosphoric acid to 1 mol, 0.0005 mol of NH4HF2 to 0.025 mol, and no H4SiO4 was added.

[0190] [Comparative manufacturing example B5] The same as Preparation Example B1 except that the amount of MnSO4·H2O was changed to 1.4 mol, the amount of FeSO4·H2O was changed to 0.6 mol, the amount of Li2CO3 was changed to 0.38 mol, and 0.001 mol of Mo(SO4)3 was replaced with 0.12 mol of MgSO4.

[0191] [Comparative manufacturing example B6] The same as Preparation Example B1 except that the amount of MnSO4·H2O was changed to 0.8 mol, 0.7 mol of FeSO4·H2O was replaced with 1.2 mol of ZnSO4, the amount of Li2CO3 was changed to 0.499 mol, and 0.001 mol of Mo(SO4)3 was replaced with 0.001 mol of MgSO4.

[0192] [Comparative manufacturing example B7] This is the same as Preparation Example B1, except that the amount of MnSO4·H2O was changed to 1.4 mol, the amount of FeSO4·H2O was changed to 0.6 mol, the amount of Li2CO3 was changed to 0.534 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.001 mol of MgSO4, the amount of phosphoric acid was changed to 0.88 mol, the amount of H4SiO4 was changed to 0.12 mol, and the amount of NH4HF2 was changed to 0.025 mol.

[0193] [Comparative manufacturing example B8] This is the same as Preparation Example B1, except that the amount of MnSO4·H2O was changed to 1.2 mol, the amount of FeSO4·H2O was changed to 0.8 mol, the amount of Li2CO3 was changed to 0.474 mol, 0.001 mol of Mo(SO4)3 was changed to 0.001 mol of MgSO4, the amount of phosphoric acid was changed to 0.93 mol, the amount of H4SiO4 was changed to 0.07 mol, and the amount of NH4HF2 was changed to 0.06 mol.

[0194] Manufacturing of mixed positive electrode active materials [Examples 1 to 43 and Comparative Example 1] The first positive electrode active material and the second positive electrode active material are stirred and mixed in a stirring tank, and the mass of the first positive electrode active material is m1, the mass of the second positive electrode active material is m2, and the mass of the mixed positive electrode active material is m1 + m2.

[0195] Table 4 shows the parameters for each example and comparative example.

[0196] [Table 4] JPEG0007780659000008.jpg190169

[0197] Full battery manufacturing The positive electrode active material, acetylene black as a conductive agent, and polyvinylidene fluoride (PVDF) as an adhesive were uniformly mixed in a weight ratio of 92:2.5:5.5 in an N-methylpyrrolidone solvent system, and then coated on aluminum foil, dried, and cold-pressed to obtain a positive electrode plate. The coating amount was 0.4 g / cm. 2 and the compaction density is 2.4 g / cm 3 is.

[0198] The negative electrode active materials, artificial graphite and hard carbon, the conductive agent acetylene black, the adhesive agent styrene butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC), were mixed uniformly in deionized water in a weight ratio of 90:5:2:2:1, and then coated on copper foil, dried, and cold-pressed to obtain a negative electrode plate. The coating amount was 0.2 g / cm. 2 and the compaction density is 1.7 g / cm 3 is.

[0199] A polyethylene (PE) porous polymer film was used as a separator. A positive electrode plate, a separator, and a negative electrode plate were stacked in this order, with the separator positioned in the center of the positive and negative electrodes to act as an insulator, and then wound up to obtain a bare cell. The bare cell was placed in an outer casing, and the same electrolyte solution as used to manufacture the button cell described below was injected and packaged to obtain a full battery (hereinafter also referred to as a "full cell").

[0200] Button battery manufacturing The positive electrode active material, polyvinylidene fluoride (PVDF), and acetylene black were added to N-methylpyrrolidone (NMP) in a weight ratio of 90:5:5 and stirred in a drying chamber to prepare a slurry. The slurry was coated on aluminum foil, dried, and cold-pressed to prepare a positive electrode plate. The coating amount was 0.2 g / cm. 2 and the compaction density is 2.0 g / cm 3 is.

[0201] A lithium sheet was used as the negative electrode, and 1 mol / L LiPF6 was dissolved in ethylene carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC) in a volume ratio of 1:1:1 as the electrolyte. Together with the positive electrode plate manufactured above, this was assembled into a button cell box as a button battery (hereinafter also referred to as a "button cell").

[0202] The positive electrode active material may be a first positive electrode active material, a second positive electrode active material, or a mixed positive electrode active material.

[0203] Material Performance Testing 1. Measurement of the chemical formula of the positive electrode active material The internal microstructure and surface structure of the positive electrode active material were characterized with high spatial resolution using a spherical aberrometer (ACSTEM), and the chemical formula of the positive electrode active material was obtained by combining with three-dimensional reconstruction techniques.

[0204] 2. Lattice change rate measurement method In a constant temperature environment of 25°C, a sample of the positive electrode active material was placed in an XRD (model number: Bruker D8 Discover) and tested at a rate of 1° / min. The test data was compiled and analyzed, and the lattice constants a0, b0, c0, and v0 (a0, b0, and c0 represent the length dimensions in each direction of the unit lattice, and v0 represents the volume of the unit lattice, which can be obtained directly from the XRD results) were calculated by referring to the specification PDF card.

[0205] The positive electrode active material was fabricated into a button cell according to the "Button Battery Fabrication" section above. The button cell was charged at a low rate of 0.05 C until the current decreased to 0.01 C. The positive electrode plate from the button cell was then removed and placed in DMC for 8 hours. After drying, the powder was scraped off and particles smaller than 500 nm were selected. The lattice constant v1 was calculated in the same manner as for the fresh test sample described above, and the lattice change rate before and after complete lithium release was calculated as (v0 - v1) / v0 × 100%, which is shown in the table.

[0206] 3.Measuring method for Li / Mn antisite defect concentration The XRD results tested using the "lattice change rate measurement method" were compared with the PDF (Powder Diffraction File) card of a standard crystal to obtain the Li / Mn antisite defect concentration. Specifically, the XRD results tested using the "lattice change rate measurement method" were input into the General Structure Analysis System (GSAS) software, and the refined results were automatically obtained. These included the occupancy status of different atoms, and the Li / Mn antisite defect concentration was obtained by reading the refined results.

[0207] 4. Surface oxygen valence measurement method A 5g sample of the positive electrode active material was fabricated into a button cell according to the "Button Cell Fabrication" procedure described above. The button cell was charged at a low rate of 0.05C until the current decreased to 0.01C. The positive electrode plate from the button cell was then removed and placed in DMC for 8 hours. After drying, the powder was scraped off and particles smaller than 500nm were selected. The resulting particles were measured using electron energy loss spectroscopy (EELS, model number: Talos F200S) to obtain the near-edge energy loss structure (ELNES), which reflected the elemental density of states and energy level distribution. The surface oxygen valence after charging was estimated by integrating the valence band density of states data and calculating the number of occupied electrons from the density of states and energy level distribution.

[0208] 5.Method of measuring compaction density Five grams of the positive electrode active material powder was placed in a compaction mold (CARVER mold, USA, model number 13 mm), and the mold was then placed on a compaction density meter. A pressure of 3 T was applied to the positive electrode active material, and the powder thickness at pressure (thickness after decompression) was read on the instrument, and the compaction density was calculated from ρ = m / v.

[0209] 6. Method for measuring the amount of dissolved Mn (and Fe doped into Mn sites) after cycling The positive electrode active material sample was fabricated as a full battery according to the above "Fabrication of a Full Battery."

[0210] The full battery, which had been cycled at 45°C until the capacity had decayed to 80%, was discharged at a rate of 0.1 C to a cutoff voltage of 2.0 V. The battery was then disassembled, the negative electrode plate was removed, and 30 unit area (1540.25 mm) particles were placed on the negative electrode plate. 2 ) wafers were randomly selected and tested for inductively coupled plasma emission spectroscopy (ICP) using an Agilent ICP-OES730. Based on the ICP results, the amounts of Fe (if Fe was doped into the Mn sites of the positive electrode active material) and Mn were calculated, and the amount of Mn (and Fe doped into the Mn sites) released after cycling was calculated. The test standard complies with EPA-6010D-2014.

[0211] 7.Measuring the initial gram capacity of button batteries The button battery was charged from 2.5 to 4.3 V at 0.1 C up to 4.3 V. It was then charged at a constant voltage of 4.3 V until the current fell to 0.05 mA or less. It was left standing for 5 minutes and then discharged at 0.1 C down to 2.0 V. The discharge capacity at this point was taken as the initial capacity and designated D0.

[0212] 8.3C constant current charging ratio measurement method A fresh, full battery was left standing at a constant temperature of 25°C for 5 minutes, then discharged at 1 / 3C to 2.5V. After leaving it standing for 5 minutes, it was charged at 1 / 3C to 4.3V. It was then charged at a constant voltage of 4.3V until the current reached 0.05mA or less. After leaving it standing for 5 minutes, the charge capacity at this point was recorded as C0. It was then discharged at 1 / 3C to 2.5V, left standing for 5 minutes, and then charged at 3C to 4.3V. After leaving it standing for 5 minutes, the charge capacity at this point was recorded as C1. The constant current charge ratio at 3C was C1 / C0 x 100%.

[0213] The higher the charging constant current ratio at 3C, the better the rate performance of the battery.

[0214] 9. Cycle performance test of full battery at 45℃ In a constant temperature environment of 45°C, a full battery was charged from 2.5 to 4.3 V at 1 C up to 4.3 V. It was then charged at a constant voltage of 4.3 V until the current fell to 0.05 mA or less. After leaving the battery stationary for 5 minutes, it was discharged at 1 C down to 2.5 V, and the discharge capacity at this point was recorded as D0. The above charge-discharge cycle was repeated until the discharge capacity fell to 80% of D0. The number of cycles the battery had gone through was recorded.

[0215] 10. Full battery expansion test at 60°C Full batteries were stored at 60°C with a 100% state of charge (SOC). Before, during, and after storage, the cell's open circuit voltage (OCV) and alternating current internal resistance (IMP) were measured to monitor the SOC, and the cell volume was also measured. After every 48 hours of storage, the full batteries were removed and left to stand for 1 hour before testing the open circuit voltage (OCV) and internal resistance (IMP). After cooling to room temperature, the cell volume was measured using the drainage method. The drainage method involved first measuring the cell's gravity (F1) independently using a balance with automatic unit conversion using the dial data, and then completely immersing the cell in deionized water (density 1 g / cm). 3 The cell is then placed in a container (known as a container) and the gravity F2 of the cell is measured. The buoyancy F 浮 is F1-F2, and Archimedes' principle F 浮 =ρ×g×V 排 Based on this, the cell volume V = (F1 - F2) / (ρ × g) was calculated.

[0216] From the results of the OCV and IMP tests, the batteries of the example always maintained an SOC of 99% or more until the end of storage in this experimental process.

[0217] After storage for 30 days, the cell volume was measured, and the rate of increase in the cell volume after storage relative to the cell volume before storage was calculated.

[0218] The remaining capacity of the cell was also measured. A full battery was charged at 1C from 2.5 to 4.3V up to 4.3V. It was then charged at a constant voltage of 4.3V until the current fell to 0.05mA or less. The battery was left to stand for 5 minutes, and the charge capacity at this time was recorded as the remaining capacity of the cell.

[0219] 11. Specific surface area (BET) measurement method In accordance with GB / T 19587-2004, the specific surface area test was performed on the positive electrode active material using a TRISTAR II 3020 specific surface area and porosity analyzer (Micromeritics, USA). Before the test, the positive electrode active material was placed in a vacuum oven and dried at 200°C for ≥ 2 hours, with a sample weight of > 20 g.

[0220] 12.Particleness D v 50 tests The particle size D of the positive electrode active material was measured using a Mastersizer 3000 laser diffraction particle size analyzer (Malvern Panalytical) in accordance with GB / T19077-2016. v 50. Here, deionized water was used as the solvent, and the positive electrode active material was subjected to ultrasonic treatment for 5 minutes before the test.

[0221] 13. ICP Test (Inductively Coupled Plasma Atomic Emission Spectroscopy) The elemental content tests were performed using an iCAP 7400 inductively coupled plasma optical emission spectrometer in accordance with EPA 6010D-2014. Aqua regia was selected as the solvent. Formula for calculating powder element content: Element content (mass%) = 100% × element mass / sample mass; formula for calculating electrode element content: Element content (mass%) = 100% × element mass / (sample mass - current collector mass).

[0222] 14. Li2CO3 and LiOH content test (free lithium potential titration test) The test was carried out using a 905 potentiometer in accordance with GB / T 9736-2008. After sampling, the samples were immediately vacuum-sealed in aluminum plastic film bags. The minimum sample size per test was ≥ 30g.

[0223] 15.Crystalline type test Unless otherwise specified, in this application, the terms "single crystal / single crystal-like particles," "quasi-single crystal particles," "single crystal particles," "single crystal material particles," and similar expressions have essentially the same meaning and refer to single particles (i.e., primary particles) and / or agglomerated particles, among which agglomerated particles are particles formed by agglomeration of 100 or less (particularly about 5 to 50) primary particles with an average particle size in the range of 50 nm to 10,000 nm.

[0224] Unless otherwise specified, in this application, the terms "secondary particles" and "polycrystalline material particles" generally have the same meaning and refer to particles formed by aggregation of more than 100 primary particles with an average particle size in the range of 50 to 800 nm.

[0225] The positive electrode active material was examined using a scanning electron microscope. The sample and magnification were adjusted so that there were more than 10 agglomerated particles in the field of view. The number of primary particles constituting each agglomerated particle was counted, and the longitudinal size of the primary particles was measured on a scale to determine the particle size. The particle sizes of the primary particles in each agglomerated particle were sorted in descending order, and the data with the largest and smallest diameters (1 / 10th of the particle size) were removed. The average of the remaining particle sizes was then taken as the average particle size of the primary particles in the agglomerated particles. If the number and average particle size of primary particles in 50% or more (including 50%) of the agglomerated particles met the definition of "polycrystalline material particles," the positive electrode active material was determined to be a polycrystalline material. Otherwise, it was determined to be a single-crystal or single-crystal-like material.

[0226] SEM photographs of the first positive electrode active materials produced in Production Examples A10 and A15 are shown in FIGS. 7 and 8. FIG.

[0227] 16. Hot Box Safety Test The test was carried out in accordance with the "heating" section of the safety test in GB 38031-2020, and the upper limit was explored. The optimized test conditions were as follows:

[0228] <1> Prerequisites: Test conditions: An explosion-proof oven capable of heating the wiring connection port was prepared. The test cell was a fresh bare cell (cycle count ≦10), with temperature-sensing wires attached to the periphery of the cell and the poles for temperature monitoring, and a temperature recording device was also installed. Cell treatment before testing: Constant current / constant voltage charging was performed at a rate current of 0.33 C, and the cell was fully charged to the nominal voltage (for example, in the present invention, the voltage is 4.3 V).

[0229] <2> Test procedure: The sample was placed in a high-temperature bath, and the bath was heated from room temperature to 100°C at 5°C / min, and maintained at this temperature for 2 hours. The temperature was then increased at 5°C / min, and maintained at this temperature for 30 minutes at 5°C intervals, until the cell went into runaway (runaway criteria: voltage drop of ≥ 50% within 1 min, cell temperature rise of ≥ 50% within 1 min) or reached 200°C, at which point heating was stopped.

[0230] <3> Data processing: Based on the above conditions, the failure point was found, and the corresponding incubation temperature and incubation time were obtained. Time @ temperature, for example, 21 min @ 150°C.

[0231] <4> Results benchmark: The longer the test duration, the safer the sample. The longer the test duration, the longer the sample may be, for example, a sample with the same failure point temperature but a longer test time, a sample with the same failure point time but a higher temperature, or a sample with different failure point temperatures and times but a higher temperature.

[0232] [Table 5] JPEG0007780659000010.jpg143169

[0233] [Table 6]

[0234] [Table 7]

[0235] [Table 8]

[0236] [Table 9]

[0237] [Table 10]

[0238] [Table 11]

[0239] As can be seen from Tables 7, 9, 10, and 11 above, the second positive electrode active materials of the present invention achieved more favorable results than the comparative examples in one or all of cycle performance, high-temperature stability, gram capacity, and compaction density.

[0240] As can be seen from the comparison between Production Examples B18-B20 and B23-B25, when other elements are the same, if (1-y):y is within the range of 1 to 4, the energy density and cycle performance of the secondary battery can be further improved.

[0241] [Table 12] JPEG0007780659000018.jpg249169

[0242] As can be seen from the comparison between Examples 1-43 and Comparative Example 1 in Table 12, compared to the secondary battery manufactured in Comparative Example 1, the secondary batteries manufactured by mixing the first positive electrode active material and the second positive electrode active material of the present application have higher cycle capacity retention rates and longer cycle lives. In addition, the safety of the secondary batteries manufactured using the mixed positive electrode active materials of Examples 1, 3-7, 9, 12-13, 23-25, and 28 of the present application is superior to the safety of the secondary battery manufactured in Comparative Example 1.

[0243] As can be seen from a comparison between Examples 16 and 23-29, the cycle capacity retention rate of a secondary battery manufactured in which the mass relationship m1 / (m1+m2) between the first positive electrode active material and the second positive electrode active material of the present application is between 3% and 50% is further improved, and the cycle life is further extended. Secondary batteries manufactured in accordance with the present invention, in which the mass relationship b×m1 / m1+m2 between the first and second positive electrode active materials is 0.457 or less, have high cycle capacity retention, long cycle life, and high safety. As can be seen from a comparison between Examples 16 and 23-29, secondary batteries manufactured in accordance with the present invention, in which the mass relationship b×m1 / (m1+m2) between the first and second positive electrode active materials is 0.025 to 0.415, have further improved cycle capacity retention, longer cycle life, and improved safety.

[0244] As can be seen from the comparison of Examples 1-11 and 22, when the first positive electrode active material of the present application is single-crystal-like, the D v The secondary battery manufactured with a particle size of 5.8 μm or less has a high cycle capacity retention rate, a long cycle life, and high safety. v The secondary batteries manufactured with particle sizes of 4.3 μm or less had higher cycle capacity retention and longer cycle life.

[0245] As can be seen from the comparison of Examples 12-21, when the first positive electrode active material of the present application is polycrystalline, the D v 50 particle size is 3.5 to 13.5 μm, and the BET specific surface area is 1.32 m 2 / g or less and the compacted density at 3T pressure is 2.92 g / cm 3 The secondary battery thus fabricated had a higher cycle capacity retention rate and a longer cycle life.

[0246] As can be seen from the comparison of Examples 1-8, 10-11, and 22, when the first positive electrode active material of the present application is single-crystal-like, the first positive electrode active material LiNi b Co d Mn e M f The secondary batteries manufactured with d in O2 selected from the range of 0.047 to 0.320 had higher cycle capacity retention rates and longer cycle lives.

[0247] The first positive electrode active material of the present application is LiNi b Co d Mn e M f The secondary batteries manufactured with b in O2 selected from the range of 0.314 to 0.970 had high cycle capacity retention, long cycle life, and high safety. As can be seen from a comparison of Examples 1-11 and 22, when the first positive electrode active material was a single crystal or pseudo-single crystal material, the secondary batteries manufactured with b greater than 0.314 and less than 0.97 (excluding the values ​​of 0.314 and 0.97) had higher cycle capacity retention and longer cycle life.

[0248] As can be seen from the comparison between Examples 10 and 22, the secondary battery manufactured using the first positive electrode active material of the present application in which the lithium carbonate mass content was 1% or less and the lithium hydroxide mass content was 1% or less had a higher cycle capacity retention rate, a longer cycle life, and higher safety.

[0249] As can be seen from a comparison between Tables 5 and 12, the safety of the secondary batteries manufactured using the mixed cathode active material containing the corresponding first cathode active material of the present application was higher than that of the secondary batteries manufactured using the first cathode active material, and the cycle capacity retention rate of the secondary batteries manufactured using the mixed cathode active material containing the corresponding first cathode active material of the present application was higher and the cycle life was longer than that of the secondary batteries manufactured using the first cathode active materials of Preparation Examples A14-A17 and A19-A21.

[0250] As can be seen from a comparison of Tables 7, 9, 10, and 11 with Table 12, the secondary batteries manufactured using the mixed positive electrode active materials containing the corresponding second positive electrode active materials of the present application had higher cycle capacity retention rates and longer cycle lives than the secondary batteries manufactured using the second positive electrode active materials of Manufacturing Examples B1, B14, B16, B25, B26, B27, B31, B47, and B55-B60.

[0251] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiments without departing from the spirit of the present application, and other methods configured by combining some of the components of the embodiments, are also included within the scope of the present application. [Explanation of symbols]

[0252] 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 secondary battery, 51 case, 52 electrode assembly, 53 cover plate

Claims

1. A positive electrode active material including a first positive electrode active material and a second positive electrode active material, The first positive electrode active material is a compound LiNi ｂ Co ｄ Mn ｅ M ｆ O ２ wherein b is selected from the range of 0.314 to 0.970, d is selected from the range of 0 to 0.320, e is selected from the range of 0.006 to 0.390, the sum of b, d, e and f is 1, and f is greater than 0, and M is one or more elements selected from Al, Mg, Ca, Na, Ti, W, Zr, Sr, Cr, Zn, Ba, B (boron), S and Y; The second positive electrode active material is a compound Li ａ A ｘ Mn １－ｙ B ｙ P １－ｚ C ｚ O ４－ｎ D ｎ wherein a is selected from the range of 0.9 to 1.1, x is selected from the range of 0.001 to 0.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, and n is selected from the range of 0.001 to 0.1; A is one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B is one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C is one or more elements selected from B (boron), S, Si, and N; and D is one or more elements selected from S, F, Cl, and Br.

2. The mass of the first positive electrode active material is m １ and the mass of the second positive electrode active material is m ２ and m １ / (m １ +m ２ 2. The positive electrode active material according to claim 1, wherein the value of (a) is 2% to 55%.

3. bxm １ / (m １ +m ２ 2. The positive electrode active material according to claim 1, wherein the value of (a) is 0.017 to 0.

457.

4. The first positive electrode active material is a single crystal or pseudo-single crystal material, and the particle size D of the first positive electrode active material is ｖ 4. The positive electrode active material according to claim 1, wherein 50 is 5.8 μm or less.

5. When the first positive electrode active material is a single crystal or pseudo-single crystal material, d is selected from the range of 0.05 to 0.320, and / or The positive electrode active material according to claim 1 , wherein b is greater than 0.314 and less than 0.

97.

6. When the first positive electrode active material is a polycrystalline material, the particle diameter D of the first positive electrode active material ｖ 50 is 3.0 to 13.5 μm, and / or The BET specific surface area of ​​the first positive electrode active material is 1.73 m ２ / g or less, and / or The compaction density of the first positive electrode active material at a pressure of 3 T is 2.90 g / cm ３ The positive electrode active material according to claim 1 , wherein the positive electrode active material is a positive electrode active material having a molecular weight of 1000 or more.

7. The positive electrode active material according to claim 1 , wherein the first positive electrode active material further contains lithium carbonate and / or lithium hydroxide.

8. 4. The positive electrode active material according to claim 1, wherein A is any one element selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B is at least two elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C is any one element selected from B (boron), S, Si, and N; and D is any one element selected from S, F, Cl, and Br.

9. wherein x is selected from the range of 0.001 to 0.005; and / or y is selected from the range of 0.01 to 0.5, and / or wherein z is selected from the range of 0.001 to 0.005; and / or 4. The positive electrode active material according to claim 1, wherein n is selected from the range of 0.001 to 0.

005.

10. (1-y): The value of y is selected from the range of 1 to 4, and a: The value of x is selected from the range of 9 to 1100. The positive electrode active material according to any one of claims 1 to 3.

11. The positive electrode active material according to claim 1 , wherein a lattice change rate of the second positive electrode active material before and after complete release of lithium is 8% or less.

12. 4. The positive electrode active material according to claim 1, wherein the second positive electrode active material has a Li / Mn antisite defect concentration of 2% or less.

13. 4. The positive electrode active material according to claim 1, wherein the second positive electrode active material has a surface oxygen valence of −1.82 or less.

14. The compaction density of the second positive electrode active material at 3 T is 2.0 g / cm ３ The positive electrode active material according to claim 1 , wherein the positive electrode active material is a positive electrode active material having a molecular weight of 1000 or more.

15. The second positive electrode active material further includes carbon, and the carbon is a compound Li ａ A ｘ Mn １－ｙ B ｙ P １－ｚ C ｚ O ４－ｎ D ｎ The positive electrode active material according to claim 1 , wherein the positive electrode active material is a metal oxide.

16. A method for producing a positive electrode active material, comprising: providing a first active cathode material and a second active cathode material; mixing the first positive electrode active material with the second positive electrode active material; The first positive electrode active material is a compound LiNi ｂ Co ｄ Mn ｅ M ｆ O ２ The second positive electrode active material comprises the compound Li ａ A ｘ Mn １－ｙ B ｙ P １－ｚ C ｚ O ４－ｎ D ｎ wherein a, b, d, e, f, x, y, z, n, M, A, B, C, and D are defined as in any one of claims 1 to 3.

17. A positive electrode plate comprising: 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 comprising the positive electrode active material according to claim 1 .

18. A secondary battery comprising the positive electrode plate according to claim 17.

19. A battery module comprising the secondary battery according to claim 18.

20. A battery pack comprising the battery module of claim 19.

21. 21. A power consuming device comprising the battery pack of claim 20.

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