Lithium ion battery positive electrode material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of lithium ion batteries, and relates to a lithium ion battery positive electrode material and a preparation method and application thereof. The positive electrode material has a porous structure, the volume of mesopores with the pore diameter of 2-20nm accounts for more than 90% of the total pore volume, the volume of pores with the pore diameter of 3-20nm accounts for more than 80% of the total pore volume of the mesopores, and the volume of pores with the pore diameter of 5-19nm accounts for more than 57% of the total pore volume of the mesopores; and the specific surface area of the positive electrode material is 0.48-1.5 m < 2 > / g. Compared with a conventional lithium ion battery positive electrode material, the lithium ion battery positive electrode material mainly contains mesopores, the pore diameter of the mesopores is mainly within the range of 2-20 nm, almost no macropores exist in particles, the pore distribution between the particles is relatively reasonable, a favorable channel can be provided for lithium ion transmission, and the lithium ion battery positive electrode material can be used for preparing the lithium ion battery positive electrode material. Therefore, high capacity can be provided, and the increase of impedance in the cycle process of the battery is relatively small.

Description

[0001] Related applications

[0002] This application is a divisional application of the parent application with application number 202111115015.9, invention name “A lithium-ion battery positive electrode material, preparation method and application”, and application date September 23, 2021. Technical Field

[0003] The present invention belongs to the technical field of lithium ion batteries and relates to a lithium ion battery positive electrode material, a preparation method and an application thereof. Background Art

[0004] The new energy market underwent dramatic changes in 2019. The growing number of electric vehicles has led to an increasing demand for the energy density and cost-effectiveness of lithium-ion batteries. Among them, cobalt in the lithium-cobalt-nickel-manganese ternary cathode material is a scarce resource and is expensive. To improve cost-effectiveness while pursuing high energy density, the nickel or manganese content is appropriately increased, thereby reducing the amount of cobalt used. Increasing the nickel content can provide a high-capacity battery, but the increased nickel content destabilizes the material structure, causing the solution to react with the electrolyte solution. Furthermore, due to repeated charge and discharge, cracks are generated in the cathode material, which deteriorates the cycle life of the lithium-ion battery, increases impedance, and reduces capacity. Therefore, there is an urgent need to develop new materials or find new materials to replace the scarce resource cobalt or reduce the amount of cobalt in the material.

[0005] Chinese patent CN102280636A discloses a positive electrode active material, a preparation method thereof, and a rechargeable lithium battery comprising the same. The positive electrode active material of the rechargeable lithium battery is prepared by a coprecipitation method to prepare a precursor, which is then mixed with a lithium source and sintered. The material includes pores having an average diameter of about 10 nm to about 60 nm, and a porosity of about 0.5% to about 20%. The material has good particle strength, thereby preventing or reducing the occurrence of crushing after extrusion. The material tends not to react with the electrolyte and exhibits good thermal stability, thereby providing a high-capacity rechargeable lithium battery. However, the chemical formula of the material is Li a Ni x Co y Mn z M k O2, where 0.45≤x≤0.65, 0.15≤y≤0.25, 0.15<z≤0.35. The cobalt content of this material is relatively high, the capacity is insufficient, and the cost performance cannot meet the requirements.

[0006] Chinese patent CN108123119A discloses a nickel-based active material for a lithium secondary battery, a preparation method thereof, and a lithium secondary battery comprising a positive electrode containing the nickel-based active material. The patent reports that a nickel-based active material is obtained by first treating a mixture of a lithium precursor and a metal hydroxide at low temperature under an oxygen atmosphere and then heat treating it at high temperature. The material may include secondary particles, and the secondary particles include agglomerates of at least two plate-like primary particles, wherein at least part of the secondary particles has a structure in which the plate-like primary particles are radially arranged, and the porosity of the outside of the secondary particles is greater than the porosity of the inside of the secondary particles. However, the patent does not specify what aspects of the problem are improved.

[0007] Chinese patent CN1856890 discloses lithium composite oxide particles for lithium secondary battery positive electrode materials, lithium secondary battery positive electrodes using the particles, and lithium secondary batteries. The patent reports a lithium composite oxide particle for a lithium secondary battery electrode material that can enhance the battery's low-temperature load characteristics and also enhance the coating properties during positive electrode manufacturing. The material, when measured by mercury intrusion porosimetry, must meet the following conditions (A) and at least one of the following conditions (B) and (C). Condition (A): On the mercury intrusion curve, the amount of mercury intrusion is less than or equal to 0.02 cm³ / g when the pressure increases from 50 MPa to 150 MPa. Condition (B): On the mercury intrusion curve, the amount of mercury intrusion is greater than or equal to 0.01 cm³ / g when the pressure increases from 50 MPa to 150 MPa. Condition (C): The average pore radius is 10 nm to 100 nm, and the pore size distribution curve has a main peak with a peak located at a pore radius of 0.5 μm to 50 μm, and a subpeak with a peak located at a pore radius of 80 nm to 300 nm. This patent mainly addresses low-temperature performance but fails to address high-temperature performance.

[0008] Chinese patent CN104272520A discloses a non-aqueous electrolyte secondary battery and a method for manufacturing the same. The patent reports that the positive electrode mixed material layer constituting the positive electrode of the non-aqueous electrolyte secondary battery has a pore size distribution curve measured by a mercury porosimeter, wherein the pore size distribution curve has a peak A of differential pore capacity in the range of 0.05 μm to 2 μm and a peak B located on the smaller pore diameter side than the peak A. The pore size distribution curve has a minimum point C between the peak A and the peak B where the differential pore capacity becomes a minimum value. The differential pore capacity X of the peak A is A and the differential pore volume X of the peak B B The differential pore volume X of the one with the larger differential pore volume L , and the differential pore volume X at the minimum point C C The ratio (X C / X LThis patent mainly reduces battery gas production and other problems by adding overcharge additives during battery manufacturing. Summary of the Invention

[0009] The technical problem to be solved by the present invention is that the pore diameter of the positive electrode material in the prior art is too large, and most of them are macroporous materials. Due to the presence of these macropores, the migration path of lithium ions is too long, so it cannot provide a high capacity for the lithium-ion battery. In addition, during the repeated charge and discharge process of the lithium-ion battery, cracks will appear in the positive electrode material particles, causing the lithium-ion battery to lose capacity during the cycle, increase internal resistance, and produce gas.

[0010] In response to the shortcomings of the prior art, the present invention provides a lithium-ion battery positive electrode material, which contains mesopores with smaller diameters. These mesopores provide more and shorter paths for the migration of lithium ions, so that the lithium-ion battery not only has a higher capacity; at the same time, the lithium-ion positive electrode material prepared by the method of the present invention basically does not produce cracks during the charging and discharging process of the lithium-ion battery, thereby preventing the capacity decay of the lithium-ion battery material during the cycle process; the present invention also provides a preparation method of the above-mentioned lithium-ion positive electrode material and a lithium-ion battery containing the above-mentioned lithium-ion positive electrode material; the present invention also provides the application of the above-mentioned lithium-ion positive electrode material or lithium-ion battery in the fields of digital batteries, power batteries or energy storage batteries.

[0011] The technical solution of the present invention:

[0012] The present invention provides a lithium ion battery positive electrode material. The positive electrode material has a porous structure, wherein the volume of mesopores with a pore diameter of 2-20 nm accounts for more than 90% of the total pore volume.

[0013] Preferably, the volume of pores with a pore diameter of 3-20 nm accounts for more than 60% of the total mesopore volume, and preferably, the volume of pores with a pore diameter of 5-19 nm accounts for more than 40% of the total mesopore volume.

[0014] Preferably, the specific surface area of ​​the positive electrode material is 0.25 to 1.5 m 2 / g, preferably, the D V 50 The particle size is 2.00 to 6.00 μm. More preferably, the total amount of free lithium in the positive electrode material is less than 2000 ppm.

[0015] Preferably, the positive electrode material contains lithium, nickel and manganese, and the nickel content of the positive electrode material is greater than the manganese content.

[0016] Preferably, the positive electrode material contains elements of the composition shown in Chemical Formula 1;

[0017] The chemical formula 1 is: Li1+a Ni x Mn y Co z A m O2, where: 0≤a≤0.25, 0.5<x≤0.97, 0<y≤0.42, 0≤z≤0.09, 0≤m≤0.03;

[0018] Wherein, A is selected from any one or two or more of the elements Mn, Co, Al, Zr, Y, Rb, Cs, W, Ce, Mo, Ba, Ti, Mg, Ta, Nb, Ca, V, Sc, Sr and B, or is selected from phosphorus-containing compounds containing at least one of the elements Ti, Al, Mg, Zr, La and Li.

[0019] The present invention also provides a method for preparing the above-mentioned lithium ion battery positive electrode material, which comprises mixing the raw materials and then performing at least two sintering and two pulverizing steps.

[0020] Preferably, the first sintering temperature is 750°C to 980°C, and the sintering time is 8 to 40 hours; the second sintering temperature is 650°C to 920°C, and the sintering time is 5 to 20 hours; preferably, the sintering atmosphere is air, oxygen, or a mixture of air and oxygen.

[0021] Preferably, the method for preparing the above-mentioned lithium-ion battery positive electrode material further comprises the following steps:

[0022] (1) mixing the crushed product with a metal A source;

[0023] (2) Sintering and crushing the mixture from step (1).

[0024] Preferably, the sintering temperature in step (2) is 300° C. to 780° C., and the sintering time is 3 to 14 hours. More preferably, the sintering atmosphere is air, oxygen, or a mixture of air and oxygen.

[0025] Preferably, in the above preparation method, the Li source is a lithium-containing oxide, a lithium-containing fluoride or a lithium-containing salt. Preferably, the Li source is selected from one or more of anhydrous lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, lithium nitrate, lithium acetate and lithium fluoride.

[0026] The present invention also provides a lithium ion battery positive electrode material, which is prepared by the above preparation method.

[0027] The present invention also provides a lithium ion battery positive electrode, comprising a current collector and a positive electrode material loaded on the current collector, wherein the positive electrode material is the above-mentioned lithium ion battery positive electrode material.

[0028] The present invention also provides a lithium ion battery, characterized in that it comprises a positive electrode, a negative electrode and an electrolyte containing a lithium salt, wherein the positive electrode is the positive electrode of the lithium ion battery described above.

[0029] The present invention also provides applications of the lithium-ion battery positive electrode material, the lithium-ion battery positive electrode, or the lithium-ion battery in the fields of digital batteries, power batteries, or energy storage batteries.

[0030] In order to solve the above-mentioned problems in the prior art, the present invention provides the following first set of technical solutions:

[0031] Technical Solution 1: A lithium-ion battery positive electrode material having a porous structure, wherein the volume of mesopores with a pore diameter of 2-20 nm accounts for more than 90% of the total pore volume.

[0032] Technical Solution 2: The lithium-ion battery positive electrode material according to Technical Solution 1, wherein the volume of pores with a pore diameter of 3-20 nm accounts for more than 60% of the total mesopore volume, and preferably, the volume of pores with a pore diameter of 5-19 nm accounts for more than 40% of the total mesopore volume.

[0033] Technical Solution 3: The lithium-ion battery positive electrode material according to Technical Solution 1 or 2, wherein the specific surface area of ​​the positive electrode material is 0.25 to 1.5 m 2 / g, preferably, the D V 50 The particle size is 2.00 to 6.00 μm. More preferably, the total amount of free lithium in the positive electrode material is less than 2000 ppm.

[0034] Technical Solution 4: A lithium-ion battery positive electrode material according to any one of Technical Solutions 1-3, wherein the positive electrode material contains lithium, nickel and manganese, and the nickel content of the positive electrode material is greater than the manganese content.

[0035] Technical Solution 5: The lithium-ion battery positive electrode material according to any one of Technical Solutions 1 to 4, comprising the elements represented by Chemical Formula 1;

[0036] The chemical formula 1 is: Li 1+a Ni x Mn y Co z A m O2, where: 0≤a≤0.25, 0.5<x≤0.97, 0<y≤0.42, 0≤z≤0.09, 0≤m≤0.03;

[0037] Wherein, A is selected from any one or two or more of the elements Mn, Co, Al, Zr, Y, Rb, Cs, W, Ce, Mo, Ba, Ti, Mg, Ta, Nb, Ca, V, Sc, Sr and B, or is selected from phosphorus-containing compounds containing at least one of the elements Ti, Al, Mg, Zr, La and Li.

[0038] Technical Solution 6: The method for preparing the lithium-ion battery positive electrode material according to any one of Technical Solutions 1-5 comprises mixing the raw materials and then sintering and crushing them at least twice.

[0039] Technical Solution 7: The preparation method according to Technical Solution 6, wherein the first sintering temperature is 750°C to 980°C, and the constant temperature time is 8 to 40 hours; the second sintering temperature is 650°C to 920°C, and the constant temperature time is 5 to 20 hours; preferably, the sintering atmosphere is air, oxygen, or a mixture of air and oxygen.

[0040] Technical Solution 8: According to the preparation method of Technical Solution 6 or 7, the preparation method of the lithium-ion battery positive electrode material further comprises the following steps:

[0041] (1) mixing the crushed product with a metal A source;

[0042] (2) Sintering and crushing the mixture from step (1).

[0043] Technical Solution 9: According to the preparation method described in Technical Solution 8, the sintering temperature in step (2) is 300°C to 780°C, and the constant temperature time is 3 to 14 hours. Preferably, the sintering atmosphere is air, oxygen, or a mixture of air and oxygen.

[0044] Technical Solution 10: The preparation method according to any one of Technical Solutions 6-9, wherein the Li source is a lithium-containing oxide, a lithium-containing fluoride or a lithium-containing salt. Preferably, the Li source is selected from one or more of anhydrous lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, lithium nitrate, lithium acetate and lithium fluoride.

[0045] Technical Solution 11: A lithium-ion battery positive electrode material, which is prepared by the preparation method described in any one of Technical Solutions 6-10.

[0046] Technical Solution 12: A lithium-ion battery positive electrode, comprising a current collector and a positive electrode material loaded on the current collector, wherein the positive electrode material is the lithium-ion battery positive electrode material described in any one of Technical Solutions 1-5 or Technical Solution 11.

[0047] Technical Solution 13: A lithium-ion battery comprising a positive electrode, a negative electrode and an electrolyte containing a lithium salt, wherein the positive electrode is the positive electrode of the lithium-ion battery described in Technical Solution 12.

[0048] Technical Solution 14: Application of the lithium-ion battery positive electrode material of any one of Technical Solutions 1-5 or Technical Solution 11, or the lithium-ion battery positive electrode of Technical Solution 12, or the lithium-ion battery of Technical Solution 13 in the fields of digital batteries, power batteries or energy storage batteries.

[0049] In addition, in order to solve the above-mentioned problems in the prior art, the present invention also provides the following second set of technical solutions.

[0050] Technical Solution 1: A positive electrode material for a lithium-ion battery, wherein the positive electrode material has a porous structure, wherein the volume of mesopores with a pore size of 2-20 nm accounts for more than 90% of the total pore volume, the volume of pores with a pore size of 3-20 nm accounts for more than 80% of the total mesopore volume, and the volume of pores with a pore size of 5-19 nm accounts for more than 57% of the total mesopore volume; the specific surface area of ​​the positive electrode material is 0.48-1.5 m 2 / g.

[0051] Technical Solution 2: According to the lithium-ion battery positive electrode material of Technical Solution 1, wherein the D of the positive electrode material V 50 The particle size is 2.00-6.00 μm, preferably 2.8-5.6 μm; further preferably, the total amount of free lithium in the positive electrode material is less than 2000 ppm.

[0052] Technical Solution 3: A lithium-ion battery positive electrode material according to Technical Solution 1 or 2, wherein the positive electrode material contains lithium, nickel and manganese, and the nickel content of the positive electrode material is greater than the manganese content.

[0053] Technical Solution 4: The lithium-ion battery positive electrode material according to any one of Technical Solutions 1-3, wherein the positive electrode material contains the elements represented by Chemical Formula 1;

[0054] The chemical formula 1 is: Li 1+a Ni x Mn y Co z A m O2, where: 0≤a≤0.25, 0.5<x≤0.97, 0<y≤0.42, 0≤z≤0.09, 0≤m≤0.03;

[0055] Wherein, A is selected from any one or two or more of the elements Mn, Co, Al, Zr, Y, Rb, Cs, W, Ce, Mo, Ba, Ti, Mg, Ta, Nb, Ca, V, Sc, Sr and B, or is selected from phosphorus-containing compounds containing at least one of the elements Ti, Al, Mg, Zr, La and Li.

[0056] Technical Solution 5: The method for preparing the lithium-ion battery positive electrode material according to any one of Technical Solutions 1-4, comprising mixing the raw materials and then sintering and crushing them at least twice.

[0057] Technical Solution 6: According to the preparation method described in Technical Solution 5, the first sintering temperature is 750℃~980℃, and the constant temperature time is 8~40 hours; the second sintering temperature is 650℃~920℃, and the constant temperature time is 5~20 hours; preferably, the sintering atmosphere is air, oxygen or a mixture of air and oxygen.

[0058] Technical Solution 7: According to the preparation method of Technical Solution 5 or 6, the preparation method of the lithium-ion battery positive electrode material further comprises the following steps:

[0059] (1) mixing the crushed product with a metal A source;

[0060] (2) Sintering and crushing the mixture from step (1).

[0061] Technical Solution 8: According to the preparation method described in Technical Solution 7, the sintering temperature in step (2) is 300°C to 780°C, and the constant temperature time is 3 to 14 hours. Preferably, the sintering atmosphere is air, oxygen, or a mixture of air and oxygen.

[0062] Technical Solution 9: The preparation method according to any one of Technical Solutions 5-8, wherein the Li source is a lithium-containing oxide, a lithium-containing fluoride or a lithium-containing salt. Preferably, the Li source is selected from one or more of anhydrous lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, lithium nitrate, lithium acetate and lithium fluoride.

[0063] Technical Solution 10: A lithium-ion battery positive electrode material, which is prepared by the preparation method described in any one of Technical Solutions 5-9.

[0064] Technical Solution 11: A lithium-ion battery positive electrode, comprising a current collector and a positive electrode material loaded on the current collector, wherein the positive electrode material is the lithium-ion battery positive electrode material described in any one of Technical Solutions 1-4 or Technical Solution 10.

[0065] Technical Solution 12: A lithium-ion battery, comprising a positive electrode, a negative electrode and an electrolyte containing a lithium salt, wherein the positive electrode is the positive electrode of the lithium-ion battery described in Technical Solution 11.

[0066] Technical Solution 13: A lithium-ion battery according to Technical Solution 12, wherein the positive electrode is made of a material including a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector, as well as a binder and a conductive additive, wherein the positive electrode active material is the lithium-ion battery positive electrode material according to any one of Technical Solutions 1-4 or the lithium-ion battery positive electrode material according to Technical Solution 10.

[0067] Technical Solution 14: A lithium-ion battery according to Technical Solution 13, wherein the binder includes polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (ester) styrene-butadiene rubber, epoxy resin and nylon and combinations thereof.

[0068] Technical Solution 15: A lithium-ion battery according to Technical Solution 13 or 14, wherein the conductive additive comprises one or more of a carbon-based material, a metal-based material, and a conductive polymer.

[0069] Technical Solution 16: A lithium-ion battery according to any one of Technical Solutions 13-15, wherein the carbon-based material is one or more of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black or carbon fiber, the metal-based material is metal powder or metal fiber of copper, nickel, aluminum or silver, and the conductive polymer is a polyphenylene derivative.

[0070] Technical Solution 17: A lithium-ion battery according to any one of Technical Solutions 12-16, wherein the negative electrode is made of a material including a current collector, a negative electrode active material coated on the current collector, a binder, and a conductive additive.

[0071] Technical Solution 18: A lithium-ion battery according to any one of Technical Solutions 12-17, wherein the lithium-ion battery further comprises a separator and an aluminum-plastic film.

[0072] Technical Solution 19: Application of the lithium-ion battery positive electrode material described in any one of Technical Solutions 1-4 or Technical Solution 10, or the lithium-ion battery positive electrode described in Technical Solution 11, or the lithium-ion battery described in any one of Technical Solutions 12-18 in the fields of digital batteries, power batteries or energy storage batteries.

[0073] Beneficial effects of the present invention:

[0074] Compared with conventional lithium-ion battery positive electrode materials, the pores contained in the lithium-ion battery positive electrode material of the present invention are mainly mesopores, and the pore diameter of the mesopores is mainly in the range of 2-20nm, and the volume of mesopores in the range of 2-20nm accounts for more than 90% of the total pore volume. There are almost no large pores inside the particles, the structure of the particles is relatively stable, and the particles will not break during repeated charge and discharge processes, so they have good cycle performance; the pore distribution between particles is relatively reasonable, which can provide a favorable channel for lithium ion transmission, thereby providing a higher capacity, and at the same time, the increase in impedance during the battery cycle is relatively small; if the above range is exceeded, the distance of lithium ion transmission will increase, the capacity will decrease, and the impedance will increase rapidly. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 This is a pore size distribution curve of the lithium-ion battery positive electrode material prepared in Example 1;

[0076] Figure 2 This is a pore size distribution curve of the lithium-ion battery positive electrode material prepared in Example 2;

[0077] Figure 3 This is a pore size distribution curve of the lithium-ion battery positive electrode material prepared in Example 6;

[0078] Figure 4 This is a pore size distribution curve of the lithium-ion battery positive electrode material prepared in Example 7. DETAILED DESCRIPTION

[0079] To make the purpose, technical solutions, and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. The embodiments described below are part of the embodiments of the present invention, not all of them. In combination with the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0080] In the description of the present invention, pore size distribution refers to the change in the proportion of pore volumes of different pore sizes to the total pore volume as the pore size changes.

[0081] In the description of the present invention, mesopores refer to pores with a pore diameter of 2-50 nm, that is, pores of 2 nm and above and 50 nm and below, micropores refer to pores with a pore diameter less than 2 nm, and macropores refer to pores with a pore diameter greater than 50 nm.

[0082] In order to better understand the above technical solution, the present invention is further described in detail below.

[0083] The present invention provides a lithium ion battery positive electrode material. The positive electrode material has a porous structure, wherein the volume of mesopores with a pore diameter of 2-20 nm accounts for more than 90% of the total pore volume.

[0084] In a preferred embodiment of the present invention, the volume of pores with a pore diameter of 3-20 nm accounts for more than 60% of the total mesopore volume. Preferably, the volume of pores with a pore diameter of 5-19 nm accounts for more than 40% of the total mesopore volume.

[0085] In another preferred embodiment of the present invention, the specific surface area of ​​the positive electrode material is 0.25 to 1.5 m 2 / g, preferably, the D V 50 The particle size is 2.00 to 6.00 μm. More preferably, the total amount of free lithium in the positive electrode material is less than 2000 ppm.

[0086] In another preferred embodiment of the present invention, the positive electrode material comprises lithium, nickel and manganese, and the nickel content of the positive electrode material is greater than the manganese content.

[0087] In another preferred embodiment of the present invention, the positive electrode material contains elements of the composition shown in Chemical Formula 1;

[0088] The chemical formula 1 is: Li 1+a Ni x Mn y Co z A m O2, where: 0≤a≤0.25, 0.5<x≤0.97, 0<y≤0.42, 0≤z≤0.09, 0≤m≤0.03;

[0089] Wherein, A is selected from any one or two or more of the elements Mn, Co, Al, Zr, Y, Rb, Cs, W, Ce, Mo, Ba, Ti, Mg, Ta, Nb, Ca, V, Sc, Sr and B, or is selected from phosphorus-containing compounds containing at least one of the elements Ti, Al, Mg, Zr, La and Li.

[0090] The present invention also provides a method for preparing the above-mentioned lithium ion battery positive electrode material, which comprises mixing the raw materials and then performing at least two sintering and two pulverizing steps.

[0091] The first sintering temperature is 750°C to 980°C, and the sintering time is 8 to 40 hours; the second sintering temperature is 650°C to 920°C, and the sintering time is 5 to 20 hours; preferably, the sintering atmosphere is air, oxygen, or a mixture of air and oxygen.

[0092] In a preferred embodiment of the present invention, the method for preparing the above-mentioned lithium-ion battery positive electrode material further comprises the following steps:

[0093] (1) mixing the crushed product with a metal A source;

[0094] (2) Sintering and crushing the mixture from step (1).

[0095] Wherein, the sintering temperature in step (2) is 300° C. to 780° C., and the sintering time is 3 to 14 hours. More preferably, the sintering atmosphere is air, oxygen, or a mixture of air and oxygen.

[0096] In another preferred embodiment of the present invention, in the above preparation method, the Li source is a lithium-containing oxide, a lithium-containing fluoride or a lithium-containing salt. Preferably, the Li source is selected from one or more of anhydrous lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, lithium nitrate, lithium acetate and lithium fluoride.

[0097] The present invention also provides a lithium ion battery positive electrode material, which is prepared by the above preparation method.

[0098] The present invention also provides a lithium ion battery positive electrode, comprising a current collector and a positive electrode material loaded on the current collector, wherein the positive electrode material is the above-mentioned lithium ion battery positive electrode material.

[0099] The present invention also provides a lithium ion battery comprising a positive electrode, a negative electrode and an electrolyte containing a lithium salt, wherein the positive electrode is the positive electrode of the lithium ion battery described above.

[0100] The lithium-ion battery of the present invention also includes a separator and an aluminum-plastic film. Specifically, the electrodes include a positive electrode and a negative electrode. The positive electrode is made of a positive electrode current collector, a positive electrode active material coated on the positive electrode current collector, a binder, a conductive additive, and other materials. The positive electrode active material is the aforementioned lithium-ion positive electrode material. The negative electrode is made of a current collector, a negative electrode active material coated on the current collector, a binder, a conductive additive, and other materials. The separator is a PP / PE film commonly used in the industry, used to separate the positive and negative electrodes. The aluminum-plastic film contains the positive electrode, negative electrode, separator, and electrolyte.

[0101] The binder includes polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (ester) styrene-butadiene rubber, epoxy resin and nylon, etc. and their combinations, and its function is to improve the bonding properties between the positive electrode active material particles and between the positive electrode active material particles and the current collector.

[0102] The conductive additive includes one or more of a carbon-based material, a metal-based material, and a conductive polymer. The carbon-based material is one or more of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, or carbon fiber. The metal-based material is a metal powder or metal fiber of copper, nickel, aluminum, or silver. The conductive polymer is a polyphenylene derivative.

[0103] The present invention also provides applications of the lithium-ion battery positive electrode material, the lithium-ion battery positive electrode, or the lithium-ion battery in the fields of digital batteries, power batteries, or energy storage batteries.

[0104] The beneficial effects of the present invention are further illustrated below through specific examples.

[0105] The information of the reagents and equipment used in the following examples are shown in Tables 1 and 2.

[0106] Table 1 Reagent information used in the examples

[0107]

[0108]

[0109]

[0110] Table 2 Equipment information used in the embodiment

[0111]

[0112] Example 1

[0113] Material mixing: Use a 200L plow mixer, start stirring, add 46.11kg lithium hydroxide monohydrate, 0.256kg nano titanium dioxide and 100.0kg nickel manganese hydroxide precursor Ni 0.68 Mn 0.32 (OH)2 (battery grade, purchased from Guangdong Jiana Energy Technology Co., Ltd.), stirred for 2 h and then used;

[0114] First sintering: A 36-meter roller kiln was used, the sintering temperature was set at 930°C, and a mixture of air and oxygen (oxygen content 60%, gas flow rate 8L / min) was introduced. The mixed material was loaded into the equipment for the first sintering, and the temperature was kept constant for 20 hours. The material was cooled to room temperature and pulverized with a jet mill to obtain the semi-finished product of the first sintering;

[0115] Second sintering: A 36-meter roller kiln is used, the sintering temperature is set at 800°C, and a mixture of air and oxygen (oxygen content 60%, gas flow rate 8L / min) is introduced. The semi-finished product obtained from the first sintering is loaded into the 36-meter track kiln for second sintering. The temperature is kept constant for 8 hours. The material is cooled to room temperature, crushed with a jet mill, and then demagnetized to obtain the semi-finished product for the second sintering;

[0116] Secondary mixing: Place the semi-finished product from the second sintering process into a fusion machine, start stirring, add 0.248 kg of nano titanium dioxide, and mix for 30 minutes;

[0117] For the third sintering, a 36-meter roller kiln was used, the sintering temperature was set to 750°C, and a mixture of air and oxygen (oxygen content 60%, gas flow rate 8L / min) was introduced. The secondary mixed material was loaded into a 36-meter track kiln for the third sintering, kept at a constant temperature for 6 hours, and the material was cooled to room temperature, crushed with a jet mill, demagnetized, and sieved to obtain the positive electrode material.

[0118] The chemical formula of the positive electrode material obtained by digestion with dilute hydrochloric acid and ICP detection is LiNi 0.68 Mn 0.32 Ti 0.0063 O2.

[0119] Example 2

[0120] Material mixing: Use a 200L plow mixer, start stirring, add 45.87kg lithium hydroxide monohydrate and 100kg nickel manganese cobalt hydroxide precursor Ni 0.65 Co 0.1 Mn 0.25 (OH)2 (battery grade, purchased from Guizhou Zhongwei Zhengyuan New Materials Co., Ltd.), stirred for 2 h and then used;

[0121] First sintering: A 36-meter orbital kiln was used, the sintering temperature was set at 940°C, and a mixture of air and oxygen (oxygen content 55%, gas flow rate 6L / min) was introduced. The mixed materials were loaded into the equipment for the first sintering, and the temperature was kept constant for 13 hours. The materials were cooled to room temperature and pulverized with a jet mill to obtain the semi-finished products of the first sintering;

[0122] Second sintering: A 36-meter orbital kiln is used, the sintering temperature is set at 850°C, and a mixture of air and oxygen (oxygen content 55%, gas flow rate 6L / min) is introduced. The semi-finished product obtained from the first sintering is loaded into the 36-meter orbital kiln for second sintering. The temperature is kept constant for 14 hours. The material is cooled to room temperature, crushed with a jet mill, and then demagnetized to obtain the semi-finished product for the second sintering;

[0123] Secondary mixing: put the semi-finished product of the second sintering into the fusion machine, start stirring, add 4.43kg strontium carbonate 36m track kiln, and mix for 30min;

[0124] For the third sintering, a 36-meter orbital kiln was used, the sintering temperature was set to 780°C, and a mixture of air and oxygen (oxygen content 55%, gas flow rate 6L / min) was introduced. The materials after the second mixing were loaded into the 36-meter orbital kiln for the third sintering. The temperature was kept constant for 7 hours. The materials were cooled to room temperature, crushed with a jet mill, demagnetized, and sieved to obtain the positive electrode material.

[0125] The chemical formula of the positive electrode material is LiNi, obtained by digestion with dilute hydrochloric acid and detection of nucleic acid by ICP. 0.65 Co 0.1 Mn 0.25 Sr 0.03 O2.

[0126] Example 3

[0127] Material mixing: Use a 200L plow mixer, start stirring, add 29.8kg anhydrous lithium hydroxide, 0.377kg aluminum oxide and 100kg nickel manganese hydroxide precursor Ni 0.97 Mn 0.03 (OH)2 (battery grade, purchased from Guangdong Jiana Energy Technology Co., Ltd.), stirred for 2 h and then used;

[0128] First sintering: Use a 36-meter orbital kiln, set the sintering temperature to 750°C, introduce oxygen (gas flow rate 10L / min), load the mixed materials into the equipment for the first sintering, keep the temperature constant for 40 hours, cool the materials to room temperature, and crush them with a jet mill to obtain the first sintered semi-finished product;

[0129] Second sintering: Use a 36-meter orbital kiln, set the sintering temperature to 650°C, introduce oxygen (gas flow rate 10L / min), and load the semi-finished product obtained from the first sintering into the 36-meter orbital kiln for the second sintering. Keep the temperature constant for 5 hours, cool the material to room temperature, crush it with a jet mill, and then demagnetize it to obtain the semi-finished product from the second sintering.

[0130] Secondary mixing: Place the semi-finished product from the second sintering process into a mixing tank, start stirring, add 200 kg of deionized water, add 0.614 kg of tetrabutyl zirconate solution, mix for 50 minutes, and filter to obtain a filter cake;

[0131] The third sintering was carried out in a 36-meter orbital kiln with a sintering temperature of 550°C and oxygen (oxygen flow rate 10 L / min) introduced. The filter cake after the second mixing was loaded into the 36-meter orbital kiln for the third sintering. The temperature was kept constant for 4 hours. The material was cooled to room temperature, crushed with a jet mill, demagnetized, and sieved to obtain the positive electrode material.

[0132] The chemical formula of the positive electrode material obtained by digestion with dilute hydrochloric acid and detection of nucleic acid by ICP is Li 1.15 Ni 0.97 Mn 0.0 3Al 0.0037 Zr 0.0016 O2

[0133] Example 4

[0134] Material mixing: Use a 200L plow mixer, start stirring, add 51.97kg lithium hydroxide monohydrate, 0.244kg boron oxide and 100kg nickel manganese cobalt hydroxide precursor Ni 0.78 Co 0.07 Mn 0.15 (OH)2 (battery grade, Jingmen Greenme New Materials Co., Ltd.), stirred for 2 h and then used;

[0135] First sintering: Use a 36-meter orbital kiln, set the sintering temperature to 880°C, introduce oxygen (gas flow rate 8L / min), load the mixed materials into the equipment for the first sintering, keep the temperature constant for 25 hours, cool the materials to room temperature, and crush them with a jet mill to obtain the first sintered semi-finished product;

[0136] Second sintering: Use a 36-meter orbital kiln, set the sintering temperature to 800°C, introduce oxygen (gas flow rate 8L / min), and load the semi-finished product obtained from the first sintering into the 36-meter orbital kiln for the second sintering. Keep the temperature constant for 6 hours, cool the material to room temperature, crush it with a jet mill, and then demagnetize it to obtain the semi-finished product from the second sintering.

[0137] Secondary mixing: Place the semi-finished product from the second sintering process into a fusion machine, start stirring, add 0.104 kg of boron oxide, and mix for 40 minutes;

[0138] The third sintering was carried out in a 36-meter orbital kiln with a sintering temperature of 500°C and oxygen (gas flow rate 8 L / min). The secondary mixed materials were loaded into the 36-meter orbital kiln for the third sintering and kept at a constant temperature for 8 hours. The materials were cooled to room temperature, crushed with a jet mill, demagnetized, and sieved to obtain Li 1.14 Ni 0.78 Co 0.07 Mn 0.15 B 0.01 O2 positive electrode material.

[0139] The chemical formula of the positive electrode material obtained by digestion with dilute hydrochloric acid and detection of nucleic acid by ICP is Li 1.14 Ni 0.77 Co 0.07 Mn 0.15 B 0.01O2.

[0140] Example 5

[0141] Material mixing: Use a 200L plow mixer, start stirring, add 48.46kg lithium hydroxide monohydrate and 100kg nickel manganese cobalt hydroxide precursor Ni 0.79 Co 0.02 Mn 0.19 (OH)2 (battery grade, Guangdong Jiana Energy Technology Co., Ltd.), stirred for 2 h and then used;

[0142] First sintering: Use a 36-meter orbital kiln, set the sintering temperature to 860°C, introduce oxygen (gas flow rate 7L / min), load the mixed materials into the equipment for the first sintering, keep the temperature constant for 25 hours, cool the materials to room temperature, and crush them with a jet mill to obtain the first sintered semi-finished product;

[0143] Second sintering: Using a 36-meter orbital kiln, set the sintering temperature to 780°C, introduce oxygen (gas flow rate 7L / min), and load the semi-finished product obtained from the first sintering into the 36-meter orbital kiln for the second sintering. Keep the temperature constant for 7 hours, cool the material to room temperature, crush it with a jet mill, and then demagnetize it to obtain the semi-finished product from the second sintering.

[0144] Secondary mixing: Place the semi-finished product from the second sintering process into a mixing tank, start stirring, add 80 kg of deionized water, stir for 30 minutes, and then simultaneously add a solution containing phosphorus and aluminum elements (first weigh 0.23 kg of aluminum sulfate dissolved in 2 kg of deionized water, then weigh 0.165 kg of ammonium dihydrogen phosphate dissolved in 5 kg of deionized water), mix for 40 minutes, and filter to obtain a filter cake;

[0145] The third sintering was carried out in a 36-meter orbital kiln with a sintering temperature of 300°C and air (air flow rate 15 L / min). The filter cake after the second mixing was loaded into the 36-meter orbital kiln for the third sintering. The temperature was kept constant for 14 hours. The material was cooled to room temperature, crushed with a jet mill, demagnetized, and sieved to obtain the positive electrode material.

[0146] The chemical formula of the positive electrode material obtained by digestion with dilute hydrochloric acid and detection of nucleic acid by ICP is Li 1.06 Ni 0.79 Co 0.0 2Mn 0.19 Al 0.0013 P 0.0013 O2.

[0147] Example 6

[0148] Material mixing: Use a 200L plow mixer, start stirring, add 43.24kg lithium carbonate and 100kg nickel manganese cobalt hydroxide precursor Ni0.62 Co 0.03 Mn 0.35 (OH)2 (battery grade, purchased from Guangdong Jiana Energy Technology Co., Ltd.) was stirred for 2 h and then used;

[0149] First sintering: Use a 36-meter orbital kiln, set the sintering temperature to 970°C, introduce air (air flow rate 15L / min), load the mixed materials into the equipment for the first sintering, keep the temperature constant for 8 hours, cool the materials to room temperature, and crush them with a jet mill to obtain the first sintered semi-finished product;

[0150] Second sintering: Use a 36-meter orbital kiln, set the sintering temperature to 910°C, and introduce air (air flow rate 15L / min). Load the semi-finished product obtained from the first sintering into the 36-meter orbital kiln for the second sintering. Keep the temperature constant for 20 hours. Cool the material to room temperature, crush it with a jet mill, and then demagnetize it to obtain the positive electrode material.

[0151] The chemical formula of the positive electrode material obtained by digestion with dilute hydrochloric acid and detection of nucleic acid by ICP is Li 1.08 Ni 0.62 Co 0.03 Mn 0.35 O2.

[0152] Example 7

[0153] Material mixing: Use a 200L plow mixer, start stirring, add 43.24kg lithium carbonate and 100kg nickel manganese cobalt hydroxide precursor Ni 0.62 Co 0.03 Mn 0.35 (OH)2 (battery grade, Guangdong Jiana Energy Technology Co., Ltd.), stirred for 2 h and then used;

[0154] First sintering: Use a 36-meter orbital kiln, set the sintering temperature to 970°C, introduce air (air flow rate 15L / min), load the mixed materials into the equipment for the first sintering, keep the temperature constant for 8 hours, cool the materials to room temperature, and sieve to obtain the positive electrode material.

[0155] The chemical formula of the positive electrode material obtained by digestion with dilute hydrochloric acid and detection of nucleic acid by ICP is Li 1.08 Ni 0.62 Co 0.03 Mn 0.35 O2.

[0156] Example 8

[0157] Material mixing: Use a 200L plow mixer, start stirring, add 46.96kg lithium hydroxide monohydrate, 0.256kg nano titanium dioxide and 100.0kg nickel manganese hydroxide precursor Ni0.4 Mn 0.6 (OH)2 (battery grade, Guangdong Jiana Energy Technology Co., Ltd.), stirred for 2 h and then used;

[0158] First sintering: A 36-meter roller kiln was used, the sintering temperature was set at 930°C, and a mixture of air and oxygen (oxygen content 60%, gas flow rate 8L / min) was introduced. The mixed material was loaded into the equipment for the first sintering, and the temperature was kept constant for 20 hours. The material was cooled to room temperature and pulverized with a jet mill to obtain the semi-finished product of the first sintering;

[0159] Second sintering: A 36-meter roller kiln is used, the sintering temperature is set at 800°C, and a mixture of air and oxygen (oxygen content 60%, gas flow rate 8L / min) is introduced. The semi-finished product obtained from the first sintering is loaded into the 36-meter track kiln for second sintering. The temperature is kept constant for 8 hours. The material is cooled to room temperature, crushed with a jet mill, and then demagnetized to obtain the semi-finished product for the second sintering;

[0160] Secondary mixing: Place the semi-finished product from the second sintering process into a fusion machine, start stirring, add 0.248 kg of nano titanium dioxide, and mix for 30 minutes;

[0161] For the third sintering, a 36-meter roller kiln was used, the sintering temperature was set to 750°C, and a mixture of air and oxygen (oxygen content 60%, gas flow rate 8L / min) was introduced. The secondary mixed material was loaded into a 36-meter track kiln for the third sintering, kept at a constant temperature for 6 hours, and the material was cooled to room temperature, crushed with a jet mill, demagnetized, and sieved to obtain the positive electrode material.

[0162] The chemical formula of the positive electrode material is LiNi, obtained by digestion with dilute hydrochloric acid and detection of nucleic acid by ICP. 0.4 Mn 0.6 Ti 0.0063 O2.

[0163] Experimental Example 1

[0164] The pore size distribution curve, specific surface area, particle size and total free lithium content of Examples 1-8 were determined according to the following methods.

[0165] (1) Pore size distribution curve determination method

[0166] The desorption side isotherm was measured using a Micromeritics fully automatic specific surface and porosity analyzer (TriStar II 3020). Then, the desorption side isotherm was used to calculate the pore size distribution curve using the BJH method, with the pore diameter as the abscissa and the pore volume ratio (the ratio of the pore volume of different mesopore diameters to the total mesopore volume) as the ordinate. Figure 1-4As shown in Table 3, the test results of the proportion of pore size of 2-20 nm (the proportion of pore volume of pore size of 2-20 nm to the total pore volume), the proportion of pore size of 3-20 nm (the proportion of pore volume of pore size of 3-20 nm to the total mesopore volume) and the proportion of pore size of 5-19 nm (the proportion of pore volume of pore size of 5-19 nm to the total mesopore volume) are shown in Table 3.

[0167] (2) Specific surface area determination method

[0168] The specific surface area in the present invention is determined by the gravimetric method in the gas adsorption BET method according to GB / T 19587-2004 and is measured by a Micromeritics fully automatic specific surface and porosity analyzer (TriStar II 3020). The test results are shown in Table 2.

[0169] (3) Particle size determination method

[0170] The particle size in the present invention refers to GB / T 19077-2016 particle size analysis·laser diffraction method, and is measured by Malvern, MasterSize 2000 laser particle size analyzer. The test results are shown in Table 2.

[0171] (4) Test method for total free lithium

[0172] Accurately weigh 30g ± 0.01g of sample, place the sample in a 250ml conical flask, place it in a magnetic stirrer, and add 100ml of deionized water; place the conical flask on the magnetic stirrer and stir for 30 minutes; filter the mixed solution using shaped filter paper and a funnel; use a 50ml pipette to transfer 50ml of the filtrate and place it in a 100ml beaker and place a magnet; place the beaker on a magnetic stirrer and add 2 drops of phenolphthalein indicator; titrate with 0.05mol / L hydrochloric acid standard titrant until the color of the solution changes from red to colorless, and record the 0.05mol / L hydrochloric acid standard titrant. The volume of the solution was determined as V1 (end point 1); 2 drops of methyl red indicator were added, and the indicator color changed from colorless to yellow; the solution was titrated with 0.05 mol / L hydrochloric acid standard solution until the color of the solution changed from yellow to orange; the beaker was placed on a heating furnace and heated until the solution boiled (the color of the solution changed from orange to yellow); the beaker was removed and cooled to room temperature; the beaker was then placed on a magnetic stirrer and titrated with 0.05 mol / L hydrochloric acid standard solution until the color of the solution changed from yellow to light red. The volume of the 0.05 mol / L hydrochloric acid standard solution, V2 (end point 2), was recorded. The total free lithium content was calculated according to the following formula. The test results are shown in Table 2.

[0173] Total free lithium: Li + (wt%)=V2×0.05×6.94×2×100 / (m×1000);

[0174] m---is the mass of the sample in g;

[0175] V2---is the second titration endpoint;

[0176] 6.94 – The atomic weight of lithium.

[0177] Table 3 Performance parameter test results of positive electrode materials prepared in Examples 1-8

[0178]

[0179] Experimental Example 2

[0180] Preparation and performance evaluation of lithium-ion batteries.

[0181] Prepare 454261 soft pack batteries according to the following method:

[0182] Positive electrode preparation: The positive electrode material of the present invention, conductive carbon black (SP), and binder polyvinylidene fluoride (PVDF) are added to N-methylpyrrolidone (NMP) (the weight ratio of the positive electrode material to NMP is 2.1:1) in a weight ratio of 94:3:3, and the mixture is thoroughly mixed and stirred to form a uniform slurry. The slurry is then coated on an aluminum foil current collector, dried, and pressed into a pole piece.

[0183] Negative electrode preparation: Add negative electrode artificial graphite, conductive carbon black (SP), carboxymethyl cellulose (CMC), and adhesive (SBR) in a weight ratio of 95:1:1:3 to sufficient pure water, stir to form a uniform slurry, apply it on the copper foil current collector, dry and press into a pole piece.

[0184] The separator is made of a PP / PE composite film. The pressed positive and negative electrode sheets are spot-welded to the tabs, then the separator is inserted. The package is then wound on a winder and loaded into a soft-pack fixture, sealed on the top and sides, and baked in an oven. Then, under a relative humidity of less than 1.5%, 9g of electrolyte (a mixed solvent with a mass ratio of EC:DEC:DMC = 1:1:1, containing 1M lithium hexafluorophosphate) is injected. After 48 hours of formation, the package is vacuum-sealed. The cell model is 454261.

[0185] The battery performance was tested on a Hangke battery tester according to the following method.

[0186] 1) Capacity test

[0187] Connect the prepared soft-pack battery to the test stand and start the test program. Setup steps: Set the test temperature to 25°C, let it rest for 4 hours, charge at constant current and constant voltage for 4 hours (e.g., 1 / 3C, charge to 4.2V), pause, let it rest, discharge at constant current (e.g., 1 / 3C, cut-off voltage 3.0V), pause; let it rest for 4 hours, charge at constant current and constant voltage for 4 hours (e.g., 1 / 3C, charge to 4.3V), pause, let it rest, discharge at constant current (e.g., 1C, cut-off voltage 3.0V), pause; repeat the previous steps to obtain capacity data under different voltage conditions.

[0188] 2) Cycle test

[0189] Connect the battery that has passed the above capacity test to the test stand, start the test program, and set the steps: set the test temperature to 45℃, let it stand for 4 hours, charge at constant current for 4 hours (such as 1C, charge to 4.2V or 4.3V), switch to constant voltage charging (such as charging at 4.2V or 4.3V for 2h), let it stand for 5 minutes, discharge at constant current for 4 hours (such as 1C, cut-off voltage 3.0V), let it stand for 5 minutes; repeat the previous steps starting from constant current charging and perform cycle testing to obtain the capacity retention rate of different cycle numbers.

[0190] 3) Cyclic DCR growth test:

[0191] In the cycle test described in 2), a 30-second constant current discharge step is added before the constant current discharge (the voltage difference within 30 seconds is recorded and then divided by the current to obtain the DCR). All other steps remain unchanged. Repeat the previous constant current charge and start step, and perform the cycle test to obtain the DCR growth rate at different cycle numbers (the difference between the DCR after the cycle and the DCR after the first cycle is divided by the DCR after the first cycle).

[0192] The test results are shown in Table 4.

[0193] Table 4 Cyclic performance test results

[0194]

[0195]

[0196] Note: The capacity of Example 8 was measured at 4.4V and 1 / 3C.

[0197] From Table 3 and Figure 1-4It can be seen that the pores contained in the lithium ion battery positive electrode materials prepared in Examples 1-6 are mainly mesopores, and the pore diameters of the mesopores are mainly in the range of 2-20 nm, and the percentage of the volume of mesopores in the range of 2-20 nm to the total pore volume is greater than 90%, the volume of pores in the range of 3-20 nm to the total mesopore volume is greater than 80%, and the volume of pores in the range of 5-19 nm to the total mesopore volume is greater than 57%. The specific surface area of ​​the lithium ion battery positive electrode materials prepared in Examples 1-6 is relatively large, ranging from 0.48 to 1.5 m 2 / g, and the particle size is relatively small, ranging from 2.8 to 5.6 μm; the pores contained in the positive electrode materials prepared in Examples 7 and 8 are mainly mesopores and macropores, and the mesopores in the range of 2-20 nm are relatively few, and the volume of mesopores in the range of 2-20 nm accounts for less than 40% of the total pore volume; the specific surface area of ​​the lithium ion battery positive electrode materials prepared in Examples 7 and 8 is relatively small, ranging from 0.25 to 0.32 m 2 / g, and the particle size is relatively large, ranging from 9.6 to 10.52 μm.

[0198] As can be seen from Table 4, compared with Example 7, the capacity of the lithium ion battery positive electrode materials provided by Examples 1-6 is increased, the cycle performance is improved, especially the cycle performance at high voltage is significantly improved, and the growth rate of the cycle DCR is significantly reduced; Example 7 has relatively poor cycle performance due to the large number and large macropores of the material, and is prone to cracking during the cycle, and is not suitable for high voltage. The capacity retention rate after 100 cycles at 4.3V is only 55%, and the cycle DCR increases significantly; Example 8 has a greater manganese content than the nickel content. Compared with the material of Example 1, the capacity cannot be fully utilized at low voltage, and the capacity can barely be fully utilized at high voltage, but the capacity is too low to meet the energy density requirements.

[0199] In summary, the lithium-ion battery positive electrode material provided by the present invention has mesopores with a pore size mainly in the range of 2-20 nm and a proportion greater than 90%. These mesopores provide more and shorter paths for the migration of lithium ions, so that the lithium-ion battery positive electrode material of the present invention has a higher capacity; at the same time, during the charging and discharging process of the lithium-ion battery, the positive electrode material is not prone to cracks, thereby preventing the capacity attenuation of the lithium-ion battery positive electrode material during the cycle process.

[0200] The above description is merely a preferred embodiment of the present invention and does not limit the present invention in any form. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A lithium-ion battery positive electrode material, characterized in that The positive electrode material has a porous structure, wherein the volume of mesopores with a pore diameter of 2-20 nm accounts for more than 90% of the total pore volume, the volume of pores with a pore diameter of 3-20 nm accounts for more than 80% of the total mesopore volume, and the volume of pores with a pore diameter of 5-19 nm accounts for more than 57% of the total mesopore volume; the specific surface area of ​​the positive electrode material is 0.48-1.5 m 2 / g.

2. The lithium-ion battery positive electrode material according to claim 1, characterized in that The positive electrode material D V 50 The particle size is 2.00-6.00 μm, preferably 2.8-5.6 μm; further preferably, the total amount of free lithium in the positive electrode material is less than 2000 ppm.

3. The lithium-ion battery positive electrode material according to claim 1 or 2, characterized in that The positive electrode material contains lithium, nickel and manganese, and the nickel content of the positive electrode material is greater than the manganese content.

4. The lithium-ion battery positive electrode material according to any one of claims 1 to 3, characterized in that It contains elements of the composition shown in Chemical Formula 1; The chemical formula 1 is: Li 1+a Ni x Mn y Co z A m O2, where: 0≤a≤0.25, 0.5<x≤0.97, 0<y≤0.42, 0≤z≤0.09, 0≤m≤0.03; Wherein, A is selected from any one or two or more of the elements Mn, Co, Al, Zr, Y, Rb, Cs, W, Ce, Mo, Ba, Ti, Mg, Ta, Nb, Ca, V, Sc, Sr and B, or is selected from phosphorus-containing compounds containing at least one of the elements Ti, Al, Mg, Zr, La and Li.

5. The method for preparing the positive electrode material for lithium-ion batteries according to any one of claims 1 to 4, characterized in that: The method comprises mixing raw materials and then performing sintering and pulverizing at least twice.

6. The preparation method according to claim 5, characterized in that: The first sintering temperature is 750℃~980℃, and the constant temperature time is 8~40 hours; the second sintering temperature is 650℃~920℃, and the constant temperature time is 5~20 hours; preferably, the sintering atmosphere is air, oxygen or a mixture of air and oxygen.

7. The preparation method according to claim 5 or 6, characterized in that: The method for preparing the lithium ion battery positive electrode material further comprises the following steps: (1) mixing the crushed product with a metal A source; (2) Sintering and crushing the mixture from step (1).

8. The preparation method according to claim 7, characterized in that: The sintering temperature in step (2) is 300° C. to 780° C., and the constant temperature time is 3 to 14 hours. Preferably, the sintering atmosphere is air, oxygen, or a mixture of air and oxygen.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The Li source is a lithium-containing oxide, a lithium-containing fluoride or a lithium-containing salt. Preferably, the Li source is selected from one or more of anhydrous lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, lithium nitrate, lithium acetate and lithium fluoride.

10. A positive electrode material for a lithium ion battery, characterized in that: The compound is prepared by the preparation method according to any one of claims 5 to 9.

11. A lithium ion battery positive electrode, characterized in that: The invention comprises a current collector and a positive electrode material loaded on the current collector, wherein the positive electrode material is the lithium ion battery positive electrode material according to any one of claims 1 to 4 or claim 10.

12. A lithium ion battery, characterized in that: The invention comprises a positive electrode, a negative electrode and an electrolyte containing a lithium salt, wherein the positive electrode is the positive electrode of the lithium ion battery according to claim 11.

13. The lithium-ion battery according to claim 12, wherein: The positive electrode is made of a material including a positive electrode current collector, a positive electrode active material coated on the positive electrode current collector, a binder, and a conductive additive, wherein the positive electrode active material is the lithium ion battery positive electrode material according to any one of claims 1 to 4 or the lithium ion battery positive electrode material according to claim 10.

14. The lithium-ion battery according to claim 13, wherein: The binder includes polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylated styrene butadiene rubber, epoxy resin and nylon and combinations thereof.

15. The lithium-ion battery according to claim 13 or 14, characterized in that: The conductive aid includes one or more of a carbon-based material, a metal-based material, and a conductive polymer.

16. The lithium-ion battery according to any one of claims 13 to 15, characterized in that: The carbon-based material is one or more of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black or carbon fiber; the metal-based material is metal powder or metal fiber of copper, nickel, aluminum or silver; and the conductive polymer is a polyphenylene derivative.

17. The lithium-ion battery according to any one of claims 12 to 16, characterized in that: The negative electrode is made of a material including a current collector, a negative electrode active material coated on the current collector, a binder, and a conductive additive.

18. The lithium-ion battery according to any one of claims 12 to 17, characterized in that: The lithium ion battery further comprises a separator and an aluminum-plastic film.

19. Use of the lithium-ion battery positive electrode material according to any one of claims 1 to 4 or claim 10, or the lithium-ion battery positive electrode according to claim 11, or the lithium-ion battery according to any one of claims 12 to 18 in the fields of digital batteries, power batteries or energy storage batteries.

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