Manganese-doped lithium nickelate positive electrode material and preparation method thereof, positive plate, battery and power utilization device

Abstract

The invention relates to a manganese-doped lithium nickelate positive electrode material and a preparation method thereof, a positive electrode plate, a battery and an electric device, and the preparation method comprises the following steps: S1, uniformly mixing a nickel manganese hydroxide precursor, a first lithium source and a chloride, and carrying out a molten salt method reaction in an oxygen atmosphere to obtain an intermediate product, the intermediate product contains single crystal manganese doped lithium nickelate with a manganese valence state of + 3; and S2, uniformly mixing the intermediate product with a second lithium source, and then carrying out heat treatment in an oxygen atmosphere to obtain the single-crystal manganese-doped lithium nickelate positive electrode material with the manganese valence state of + 4, wherein the dosage of the first lithium source is 100%-130% of the molar weight of the nickel manganese hydroxide precursor; the dosage of the second lithium source is less than 15% of the mass of the intermediate product; the heat preservation temperature of the heat treatment is 600-700 DEG C. According to the preparation method, the oxidation state of the manganese element can be improved, so that the cycling stability of the prepared positive electrode material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a manganese-doped lithium nickelate positive electrode material and a preparation method thereof, a positive electrode sheet, a battery and an electrical device. Background Art

[0002] Rechargeable batteries such as lithium-ion batteries (LIBs) are essential for the widespread application of portable electronic devices and electric vehicles. Cobalt-free layered lithium nickel oxide (LiNiO2) as a cathode material has a high capacity of up to 240 mAhg -1 The discharge specific capacity and higher operating voltage achieve higher energy density. However, the lithium nickel oxide material prepared by the traditional sintering method contains a lithium-poor phase with a high degree of mixing, which reduces its cycle performance. In addition, the energy required to form oxygen vacancies in lithium nickel oxide materials is low, resulting in irreversible structural phase changes during the cycle and the release of oxygen, thereby reducing the cycle stability of the material. In order to improve the performance of lithium nickel oxide positive electrode materials, some technologies have adopted methods such as interface modification, particle engineering and element doping.

[0003] In order to enhance the structural stability of the material, single crystal modification is considered to be an innovative method. For example, a technology prepares a single crystal high nickel ternary positive electrode material by a molten salt method. This method uses mixed molten salts for high-temperature calcination to obtain a single crystal high nickel ternary positive electrode material with good crystallinity, high charge and discharge capacity, and low discharge capacity attenuation rate. However, although this single crystal modification can partially solve the problem of irreversible structural phase change, it is still necessary to find other improvement methods to further improve the cycle performance.

[0004] The addition of manganese is considered to be a method to improve the cycling stability of lithium nickel oxide. For example, by using a cobalt-free layered nickel-manganese cathode material, the crystal structure of the lithium nickel oxide cathode material can be stabilized, thereby improving the stability of the material. However, the synthesis process of single-crystal nickel-manganese cathode materials generally requires water washing to remove molten salt. The water washing process will induce Li + / H + Exchange, resulting in a decrease in the manganese valence state (from +4 to +3). +3 valence manganese elements will cause the Chiang-Taylor effect and lead to structural distortion. At the same time, compared with +4 valence manganese, +3 valence manganese has more 3d orbital single electrons and a stronger magnetic frustration effect, which further leads to the structural instability of lithium nickel oxide materials. Therefore, it is necessary to develop effective strategies to increase the oxidation state of manganese elements and synthesize high-performance single crystal manganese-doped lithium nickel oxide positive electrode materials. Summary of the invention

[0005] Based on this, it is necessary to provide a manganese-doped lithium nickel oxide positive electrode material and a preparation method thereof, which can increase the oxidation state of the manganese element and thereby improve the cycle stability of the prepared positive electrode material.

[0006] In addition, the present application also provides a positive electrode sheet, a battery and an electrical device.

[0007] On the one hand, the present application provides a method for preparing a manganese-doped lithium nickel oxide positive electrode material, comprising the following steps:

[0008] S1, mixing a nickel manganese hydroxide precursor, a first lithium source and a chloride, and reacting them by a molten salt method in an oxygen atmosphere to obtain an intermediate product, wherein the intermediate product comprises a single crystal manganese-doped lithium nickelate having a manganese valence state of +3;

[0009] S2, mixing the intermediate product with a second lithium source, and then heat treating it in an oxygen atmosphere to obtain a single-crystalline manganese-doped lithium nickel oxide positive electrode material with a manganese valence of +4;

[0010] The amount of the first lithium source is 100% to 130% of the molar amount of the nickel manganese hydroxide precursor; the amount of the second lithium source is less than 15% of the mass of the intermediate product; and the insulation temperature of the heat treatment is 600° C. to 700° C.

[0011] In some embodiments, the nickel manganese hydroxide precursor is Ni 0.95 Mn 0.05 (OH) x Precursor, the molecular formula of the single-crystalline manganese-doped lithium nickel oxide positive electrode material with a manganese valence of +4 is Li 1+x (Ni 0.95 Mn 0.05 ) 1-x O2, -0.1≤ x < 0.2.

[0012] In some of the embodiments, the holding temperature of the molten salt method is 600°C to 700°C, the holding time is 10 h to 20 h, and the rate of heating to the holding temperature of the molten salt method is 1°C / min to 10°C / min.

[0013] In some embodiments, the holding time of the heat treatment is 0.5 h to 6 h, and the rate of heating to the holding temperature of the heat treatment is 1 °C / min to 10 °C / min.

[0014] In some embodiments, the first lithium source and the second lithium source each independently include at least one of lithium hydroxide, lithium carbonate, lithium nitrate and lithium acetate; and / or,

[0015] The mass ratio between the second lithium source and the intermediate product is 10% to 12%.

[0016] In some embodiments, the chloride comprises at least one of sodium chloride, potassium chloride, lithium chloride, ferric chloride, calcium chloride and copper chloride; and / or,

[0017] The molar ratio of the chloride to the nickel manganese hydroxide precursor is less than 1.

[0018] On the other hand, the present application also provides a manganese-doped lithium nickel oxide positive electrode material, which is prepared using the above-mentioned preparation method.

[0019] On the other hand, the present application also provides a positive electrode sheet, including the above-mentioned manganese-doped lithium nickel oxide positive electrode material.

[0020] On the other hand, the present application also provides a battery, including the above-mentioned manganese-doped lithium nickel oxide positive electrode material or the above-mentioned positive electrode sheet.

[0021] On the other hand, the present application also provides an electrical device, including the above-mentioned manganese-doped lithium nickel oxide positive electrode material, such as the above-mentioned positive electrode sheet or the above-mentioned battery.

[0022] In view of the problem that the manganese-doped lithium nickel oxide positive electrode material prepared by traditional technology has poor stability, the present application proposes a two-step preparation method. First, nickel manganese hydroxide is used as a precursor, and a molten salt chemical method is adopted and the molar amount ratio of the first lithium source and the nickel manganese hydroxide precursor is controlled to obtain an intermediate product containing single-crystalline manganese-doped lithium nickel oxide with a manganese valence state of +3. The intermediate product and the second lithium source are then heat-treated for secondary lithiation, and the temperature of the heat treatment and the amount of the second lithium source in the heat treatment are controlled within a lower range to regulate the stoichiometric ratio of lithium and nickel and manganese, so that the manganese valence state is changed to +4, and finally a single-crystalline manganese-doped lithium nickel oxide positive electrode material with a manganese valence state of +4 is obtained.

[0023] The preparation method of the manganese-doped lithium nickelate positive electrode material of the present application does not require the addition of an additional manganese source during the preparation process. It only adds a lithium source to sintering by using nickel manganese hydroxide as a precursor, and adjusts the ratio of lithium to nickel and manganese elements to ensure that manganese is fully oxidized to a valence of +4. The specific capacity of the prepared positive electrode material is relatively high, thereby greatly reducing the modification cost. In addition, the manganese valence state of the manganese-doped lithium nickelate positive electrode material prepared by the above-mentioned preparation method of the present application is +4, which reduces the influence of the Jan-Taylor effect and super exchange effect brought by +3-valent manganese, and effectively improves the cycle stability of the material.

[0024] Therefore, the single crystal manganese-doped lithium nickel oxide positive electrode material prepared by the above preparation method has high comprehensive performance and can be applied to batteries such as lithium-ion batteries, thereby obtaining good cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Ni used in Example 1 0.95 Mn 0.0 5(OH)x Scanning electron micrograph of the precursor;

[0026] Figure 2 The product Li obtained in Example 1 1.1 (Ni 0.95 Mn 0.05 ) 0.9 Scanning electron microscope image of O2;

[0027] Figure 3 The product Li obtained in Example 1 1.1 (Ni 0.95 Mn 0.05 ) 0.9 X-ray diffraction test results of O2;

[0028] Figure 4 The cycle performance curve of the button battery prepared in Example 1 at 1 C. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0031] "Scope" disclosed in the present application can be limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or excluding end values, and any end value can be included or not included independently, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 listed, and if the maximum range values ​​3,4 and 5 are also listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0032] On one hand, the present application provides a method for preparing a manganese-doped lithium nickel oxide positive electrode material, comprising the following steps S1-S2.

[0033] S1, mixing a nickel manganese hydroxide precursor, a first lithium source and a chloride, and reacting them by a molten salt method in an oxygen atmosphere to obtain an intermediate product, wherein the intermediate product comprises a single crystal manganese-doped lithium nickelate having a manganese valence state of +3;

[0034] S2, mixing the intermediate product with a second lithium source, and then heat treating it in an oxygen atmosphere to obtain a single-crystalline manganese-doped lithium nickel oxide positive electrode material with a manganese valence state of +4;

[0035] The amount of the first lithium source is 100% to 130% of the molar amount of the nickel manganese hydroxide precursor; the amount of the second lithium source is less than 15% of the mass of the intermediate product; and the insulation temperature of the heat treatment is 600°C to 700°C.

[0036] In view of the problem that the manganese-doped lithium nickel oxide positive electrode material prepared by traditional technology has poor stability, the present application proposes a two-step preparation method. First, nickel manganese hydroxide is used as a precursor, and a molten salt chemical method is adopted and the molar amount ratio of the first lithium source and the nickel manganese hydroxide precursor is controlled to obtain an intermediate product containing single-crystalline manganese-doped lithium nickel oxide with a manganese valence state of +3. The intermediate product and the second lithium source are then heat-treated for secondary lithiation, and the temperature of the heat treatment and the amount of the second lithium source in the heat treatment are controlled within a lower range to regulate the stoichiometric ratio of lithium and nickel and manganese, so that the manganese valence state is changed to +4, and finally a single-crystalline manganese-doped lithium nickel oxide positive electrode material with a manganese valence state of +4 is obtained.

[0037] The preparation method of the manganese-doped lithium nickelate positive electrode material of the present application does not require the addition of an additional manganese source during the preparation process. It only adds a lithium source to sintering by using nickel manganese hydroxide as a precursor, and adjusts the ratio of lithium to nickel and manganese elements to ensure that manganese is fully oxidized to a valence of +4. The specific capacity of the prepared positive electrode material is relatively high, thereby greatly reducing the modification cost. In addition, the manganese valence state of the manganese-doped lithium nickelate positive electrode material prepared by the above-mentioned preparation method of the present application is +4, which reduces the influence of the Jan-Taylor effect and super exchange effect brought by +3-valent manganese, and effectively improves the cycle stability of the material.

[0038] Therefore, the single crystal manganese-doped lithium nickel oxide positive electrode material prepared by the above preparation method has high comprehensive performance and can be applied to batteries such as lithium-ion batteries, thereby obtaining good cycle stability.

[0039] As an example, the amount of the first lithium source used is 100%, 110%, 120%, or 130% of the molar amount of the nickel manganese hydroxide precursor.

[0040] As an example, the mass ratio between the second lithium source and the intermediate product is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 8.5%, 9%, 9.5%, 10%, 11%, 12%, 13%, 14%. Further, the mass ratio between the second lithium source and the intermediate product is 1% to 14%, and further 10% to 12%.

[0041] In some embodiments, the nickel manganese hydroxide precursor includes but is not limited to Ni 0.95 Mn 0.05 (OH) x Precursor. Further, the nickel manganese hydroxide precursor is Ni 0.95 Mn 0.05 (OH) x Precursor, the molecular formula of the single crystal manganese-doped lithium nickel oxide positive electrode material with a manganese valence of +4 is Li 1+x (Ni 0.95 Mn 0.05 ) 1-xO2, -0.1 ≤ x < 0.2. Further, x can be -0.1, -0.05, 0, 0.05, 0.1, 0.15.

[0042] In some of the embodiments, the holding temperature of the molten salt method is 600°C to 700°C, the holding time is 10 h to 20 h, and the rate of heating to the holding temperature of the molten salt method is 1°C / min to 10°C / min.

[0043] As an example, the holding temperature of the molten salt method is 600 ℃, 630 ℃, 650 ℃, 660 ℃, 680 ℃, 700 ℃. Further, it can also be within the range formed by any two of the above point values ​​as end values, and the following is similar. As an example, the holding time can be 10 h, 12 h, 14 h, 16 h, 18 h, 20 h. As an example, the rate of heating to the holding temperature of the molten salt method is 1 ℃ / min, 2 ℃ / min, 3 ℃ / min, 4 ℃ / min, 5 ℃ / min, 6 ℃ / min, 8 ℃ / min, 10 ℃ / min.

[0044] In some embodiments, the holding temperature of the heat treatment is 600°C to 700°C, the holding time is 0.5h to 6h, and the rate of heating to the holding temperature of the heat treatment is 1°C / min to 10°C / min.

[0045] As an example, the holding temperature of the above heat treatment is 600 ℃, 630 ℃, 650 ℃, 660 ℃, 680 ℃, 700 ℃. Further, it can also be within the range formed by any two of the above point values ​​as end values, and the following is similar. As an example, the holding time can be 0.4 h, 12 h, 14 h, 16 h, 18 h, 20 h. As an example, the rate of heating to the holding temperature of the heat treatment is 1 ℃ / min, 2 ℃ / min, 3 ℃ / min, 4 ℃ / min, 5 ℃ / min, 6 ℃ / min, 8 ℃ / min, 10 ℃ / min.

[0046] In some embodiments, the first lithium source and the second lithium source are both decomposable lithium sources; further, the first lithium source and the second lithium source each independently include at least one of lithium hydroxide, lithium carbonate, lithium nitrate and lithium acetate. It is understood that the specific types of the first lithium source and the second lithium source can be the same or different.

[0047] In some embodiments, the chloride includes at least one of sodium chloride, potassium chloride, lithium chloride, ferric chloride, calcium chloride and copper chloride. Further, the chloride includes at least one of lithium chloride and sodium chloride. Further, the molar ratio of chloride to nickel manganese hydroxide precursor is less than 1.

[0048] On the other hand, the present application also provides a manganese-doped lithium nickel oxide positive electrode material, which is prepared using the above-mentioned preparation method.

[0049] On the other hand, the present application also provides a positive electrode sheet, including the above-mentioned manganese-doped lithium nickel oxide positive electrode material.

[0050] In some embodiments, the positive electrode sheet includes a current collector and an active layer. The current collector may be a metal foil. The active layer includes the above-mentioned manganese-doped lithium nickel oxide positive electrode material. Furthermore, the active layer may also include a conductive agent and a binder.

[0051] In some of the embodiments, the positive electrode sheet can be obtained by mixing the manganese-doped lithium nickel oxide positive electrode material conductive agent, binder and solvent to form an active slurry, and then coating the active slurry on a current collector and drying it.

[0052] In some of the embodiments, in the active layer, the mass content of the manganese-doped lithium nickel oxide positive electrode material is 75% to 96%, for example, 75%, 80%, 85%, 90%, 95%, 96%, and 98%.

[0053] In some of the embodiments, in the active layer, the mass content of the conductive agent is 2% to 20%, for example, 2%, 5%, 8%, 10%, 15%, or 20%.

[0054] In some of the embodiments, in the active layer, the mass content of the binder is 2% to 20%, for example, 2%, 5%, 8%, 10%, 15%, or 20%.

[0055] It is understood that the conductive agent and the binder may be any agent known in the art.

[0056] On the other hand, the present application also provides a battery, including the above-mentioned manganese-doped lithium nickel oxide positive electrode material or the above-mentioned positive electrode sheet.

[0057] In some embodiments, the battery further includes a negative electrode sheet, and the positive electrode sheet is arranged opposite to the negative electrode sheet.

[0058] The battery also includes a separator, and the battery also includes an electrolyte, which is impregnated in the positive electrode plate and the negative electrode plate. The electrolyte includes an electrolyte salt and a solvent. The electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorobis(oxalatophosphate) (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0059] In some of the embodiments, the solvent may include one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate, fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0060] The battery further comprises a separator, which can be a separator known in the art. In some embodiments, the material of the separator can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0061] On the other hand, the present application also provides an electrical device, including the above-mentioned manganese-doped lithium nickel oxide positive electrode material, such as the above-mentioned positive electrode sheet or the above-mentioned battery.

[0062] The electrical devices may include, but are not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc. Among them, the mobile devices may be, for example, mobile phones, laptop computers, etc.; the electric vehicles may be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but are not limited to these.

[0063] In order to make the purpose, technical solutions and advantages of the present invention more concise and clear, the present invention is described with the following specific embodiments, but the present invention is by no means limited to these embodiments. The embodiments described below are only preferred embodiments of the present invention, which can be used to describe the present invention and cannot be understood as limiting the scope of the present invention. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0064] In order to better illustrate the present invention, the present invention is further described below in conjunction with the embodiments. The following are specific embodiments.

[0065] Embodiment 1:

[0066] A single crystal manganese-doped lithium nickel oxide positive electrode material specifically comprises the following steps:

[0067] S1, weigh 1.00 g Ni 0.95 Mn 0.05 (OH) x The precursor, 0.70 g lithium hydroxide, 0.30 g lithium chloride and 0.20 g sodium chloride were ground evenly in a mortar, placed in a corundum crucible, placed in a tube furnace filled with oxygen, heated to 630 ° C at a rate of 5 ° C / min, kept warm for 14 h, and cooled naturally; the obtained material was dispersed in 100 mL deionized water, stirred, filtered, and dried at 80 ° C for 2 h to obtain a single crystal manganese-doped lithium nickel oxide positive electrode material with a manganese valence state of +3;

[0068] S2, weigh 0.50 g of the single crystal manganese-doped lithium nickel oxide positive electrode material with a manganese valence state of +3 prepared in S1 and 0.05 g of lithium hydroxide, grind them evenly in a mortar, put them in a corundum crucible, put them in a tubular furnace filled with oxygen, heat them to 680 ° C at a rate of 5 ° C / min, keep them at this temperature for 6 h, and cool them naturally to obtain a single crystal Li 1.1 (Ni 0.95 Mn 0.05 ) 0.9 O2 positive electrode material.

[0069] A button battery, the preparation method of which comprises the following steps: 1.1 (Ni 0.95 Mn 0.05 ) 0.9 O2 positive electrode material, super-p conductive agent and polyvinylidene fluoride binder are mixed into a uniform slurry in a mass ratio of 8:1:1 with the addition of N-methyl-2-pyrrolidone, and evenly coated on aluminum foil by coating. After drying and rolling, they are punched into round electrode sheets and vacuum dried at 120 °C for 12 h. They are used as the positive electrode, the metal lithium sheet as the negative electrode, the electrolyte contains 1 mol / L LiPF6, the solvent is EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) (volume ratio of 1:1:1), and Celgard 2500 microporous membrane as the separator, and assembled into button batteries in a glove box.

[0070] Comparative Example 1:

[0071] The method is basically the same as Example 1, except that step S2 is omitted, and the single crystal manganese-doped lithium nickel oxide positive electrode material with a manganese valence state of +3 obtained in step S1 is directly used to prepare a button battery.

[0072] The single crystal manganese-doped lithium nickel oxide positive electrode material, the preparation method thereof comprises the following steps:

[0073] S1, weigh 1.00 g Ni 0.95 Mn 0.05 (OH) x The precursor, 0.70 g lithium hydroxide, 0.30 g lithium chloride and 0.20 g sodium chloride were ground evenly in a mortar, placed in a corundum crucible, placed in a tube furnace filled with oxygen, heated to 630 ° C at a rate of 5 ° C / min, kept warm for 14 h, and cooled naturally; the obtained material was dispersed in 100 mL deionized water, stirred, filtered, and dried at 80 ° C for 2 h to obtain a single crystal manganese-doped lithium nickel oxide positive electrode material with a manganese valence state of +3;

[0074] A button battery, the preparation method of which comprises the following steps: adding N-methyl-2-pyrrolidone to a single crystal manganese-doped lithium nickelate positive electrode material with a manganese valence state of +3 prepared by S1, a super-p conductive agent and a polyvinylidene fluoride binder in a mass ratio of 8:1:1 to mix into a uniform slurry, coating it evenly on an aluminum foil by a coating method, drying and rolling it, punching it into a circular electrode sheet, and vacuum drying it at 120°C for 12 h; using the positive electrode as the positive electrode, a metal lithium sheet as the negative electrode, an electrolyte containing 1 mol / L LiPF6, a solvent of EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) (volume ratio of 1:1:1), and a Celgard 2500 microporous membrane as a diaphragm, and assembling the button battery in a glove box.

[0075] Embodiment 2:

[0076] A single crystal manganese-doped lithium nickel oxide positive electrode material, the preparation method of which comprises the following steps:

[0077] S1, weigh 1.00 g Ni 0.95 Mn 0.05 (OH) x The precursor, 1.00 g lithium nitrate, 0.30 g lithium chloride and 0.10 g sodium chloride were ground evenly in a mortar, placed in a corundum crucible, placed in a tube furnace filled with oxygen, heated to 630 ° C at a rate of 5 ° C / min, kept warm for 14 h, and cooled naturally; the obtained material was dispersed in 100 mL deionized water, stirred, filtered, and dried at 80 ° C for 2 h to obtain a single crystal manganese-doped lithium nickel oxide positive electrode material with a manganese valence of +3;

[0078] S2, weigh 0.50 g of the single crystal manganese-doped lithium nickel oxide positive electrode material with a manganese valence state of +3 prepared in S1 and 0.04 g of lithium hydroxide, grind them evenly in a mortar, put them in a corundum crucible, put them in a tubular furnace filled with oxygen, heat them to 650 ° C at a rate of 5 ° C / min, keep them warm for 3 h, and cool them naturally to obtain a single crystal Li 0.95 (Ni 0.95 Mn 0.05 ) 1.05 O2 positive electrode material.

[0079] A button battery, the preparation method of which comprises the following steps: 0.95 (Ni 0.95 Mn 0.05 ) 1.05 O2 positive electrode material, super-p conductive agent and polyvinylidene fluoride binder are mixed into a uniform slurry with a mass ratio of 9.2:0.4:0.4, and N-methyl-2-pyrrolidone is added. It is evenly coated on aluminum foil by coating method, dried and rolled, and then punched into round electrode sheets, which are vacuum dried at 120 °C for 12 h; it is used as the positive electrode, the metal lithium sheet is used as the negative electrode, the electrolyte contains 1 mol / L LiPF6, the solvent is EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) (volume ratio of 1:1:1), and Celgard 2500 microporous membrane is used as the separator, and assembled into a button battery in a glove box.

[0080] Example 3

[0081] It is basically the same as Example 1, except that in step S2, the content of lithium hydroxide is 0.06 g, so the mass ratio W of lithium hydroxide and single crystal manganese-doped lithium nickel oxide positive electrode material with a manganese valence state of +3 in S1 is different, and the other steps are the same.

[0082] Step S2 is as follows: 0.50 g of the single crystal manganese-doped lithium nickelate positive electrode material with a manganese valence state of +3 obtained in S1 and 0.06 g of lithium hydroxide are weighed respectively, ground evenly in a mortar, placed in a corundum crucible, placed in a tubular furnace filled with oxygen, heated to 680 ° C at a rate of 5 ° C / min, kept warm for 6 h, and cooled naturally to obtain a single crystal Li 1.1 (Ni 0.95 Mn 0.05 ) 0.9 O2 positive electrode material.

[0083] The following is a performance test.

[0084] The precursors used in each embodiment and comparative example are Ni 0.95 Mn 0.05 (OH) xPrecursor, the Ni used in Example 1 0.95 Mn 0.05 (OH) x Precursors such as Figure 1 As shown. Figure 1 It can be seen that the precursor is a spherical secondary agglomerate with a particle size of about 5 μm.

[0085] The product Li obtained in Example 1 1.1 (Ni 0.95 Mn 0.05 ) 0.9 The scanning electron microscope image and X-ray diffraction test results of O2 are shown in Figure 2 and Figure 3 As shown. Figure 2 and Figure 3 It can be seen that Li 1.1 (Ni 0.95 Mn 0.05 ) 0.9 The O2 positive electrode material is submicron single crystal particles.

[0086] The cycle performance curve of the button battery prepared in Example 1 at 1 C is as follows: Figure 4 The results show that Li 1.1 (Ni 0.95 Mn 0.05 ) 0.9 The discharge capacity of O2 after 80 cycles is 175 mAhg -1 , the capacity retention rate is 93%. This shows that the product Li prepared in Example 1 1.1 (Ni 0.95 Mn 0.05 ) 0.9 O2 has high cycle stability.

[0087] The discharge specific capacity and capacity retention rate after 80 cycles at 1 C of other embodiments and comparative examples are shown in Table 1. The mass ratio of lithium hydroxide to single crystal manganese-doped lithium nickel oxide positive electrode material with a manganese valence of +3 in S1 is recorded as W.

[0088] Table 1 XPS test results

[0089]

[0090] It can be seen from Table 1 that, compared with the comparative example, in the preparation method provided in the present application, the valence state of manganese in the material can be increased by the secondary lithiation method, and the +3-valent manganese element will cause the Jiang-Taylor effect and cause structural distortion. At the same time, compared with +4-valent manganese, +3-valent manganese has more 3d orbital single electrons and has a stronger magnetic frustration effect, which leads to the instability of the structure of the lithium nickelate material. Therefore, Example 1 has a +4-valent manganese element, which means that its stability is improved.

[0091] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims, and the description and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing a manganese-doped lithium nickel oxide positive electrode material, characterized in that: The steps include: S1, mixing a nickel manganese hydroxide precursor, a first lithium source and a chloride, and reacting them by a molten salt method in an oxygen atmosphere to obtain an intermediate product, wherein the intermediate product comprises a single crystal manganese-doped lithium nickelate having a manganese valence state of +3; S2, mixing the intermediate product with a second lithium source, and then heat treating it in an oxygen atmosphere to obtain a single-crystalline manganese-doped lithium nickel oxide positive electrode material with a manganese valence of +4; The amount of the first lithium source is 100% to 130% of the molar amount of the nickel manganese hydroxide precursor; the amount of the second lithium source is less than 15% of the mass of the intermediate product; and the insulation temperature of the heat treatment is 600°C to 700°C.

2. The preparation method according to claim 1, characterized in that The nickel manganese hydroxide precursor is Ni 0.95 Mn 0.05 (OH) x Precursor, the molecular formula of the single-crystalline manganese-doped lithium nickel oxide positive electrode material with a manganese valence of +4 is Li 1+x (Ni 0.95 Mn 0.05 ) 1-x O2, -0.1 ≤ x<0.

2.

3. The preparation method according to claim 1, characterized in that: The holding temperature of the molten salt method is 600°C to 700°C, the holding time is 10 h to 20 h, and the rate of heating to the holding temperature of the molten salt method is 1°C / min to 10°C / min.

4. The preparation method according to claim 1, characterized in that: The holding time of the heat treatment is 0.5 h to 6 h, and the rate of heating to the holding temperature of the heat treatment is 1 °C / min to 10 °C / min.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The first lithium source and the second lithium source each independently include at least one of lithium hydroxide, lithium carbonate, lithium nitrate and lithium acetate; and / or, The mass ratio between the second lithium source and the intermediate product is 8% to 12%.

6. The preparation method according to any one of claims 1 to 4, characterized in that: The chloride comprises at least one of sodium chloride, potassium chloride, lithium chloride, ferric chloride, calcium chloride and copper chloride; and / or, The molar ratio of the chloride to the nickel manganese hydroxide precursor is less than 1.

7. A manganese-doped lithium nickel oxide positive electrode material, characterized in that: The method is prepared according to any one of claims 1 to 6.

8. A positive electrode sheet, characterized in that: It includes the manganese-doped lithium nickel oxide positive electrode material as described in claim 7.

9. A battery, characterized in that: It includes the manganese-doped lithium nickel oxide positive electrode material as described in claim 7 or the positive electrode sheet as described in claim 8.

10. An electrical device, characterized in that: It includes the manganese-doped lithium nickel oxide positive electrode material as claimed in claim 7, the positive electrode sheet as claimed in claim 8 or the battery as claimed in claim 9.

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