A positive electrode material, a preparation method thereof, a positive electrode sheet, a battery, and a consumer electronic device

Abstract

The application provides a positive electrode material, a preparation method thereof, a positive electrode sheet, a battery and an electric device. The positive electrode material is a single crystal positive electrode material, and a molecular formula of the positive electrode material is as follows: LiNi e Co f Mn g M d O 2‑x F x , wherein 0.8<=e<=0.98, 0<=f<=0.1, 0.02<=g<=0.20, 0 The positive electrode material is applied to the battery, and the cycle performance, the rate performance and the capacity of the battery can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of positive electrode material and its preparation method, positive electrode sheet, battery and electric equipment, belong to new energy technology field. BACKGROUND

[0002] In recent years, in various commercialization chargeable and dischargeable chemical energy storage devices, lithium ion battery is always attracted much attention since being put into market due to having environment-friendly and long service life, and is widely used in mobile phone, notebook computer, electric vehicle and other fields. Positive electrode material is an important component of lithium ion battery, and the performance of positive electrode material will directly affect the comprehensive performance of lithium ion battery. Among them, nickel-cobalt-manganese ternary positive electrode material (NCM), especially high-nickel ternary material is considered as the most favorable candidate in the next generation of lithium ion battery positive electrode material due to having higher specific capacity.

[0003] However, with the increase of nickel element content in positive electrode material, nickel ion is prone to lithium-nickel mixing with lithium ion, which is not conducive to the cycle performance of battery, and the increase of nickel element content in positive electrode material will inevitably cause the decrease of lithium element content, and low lithium element content will not be conducive to the lithium ion deintercalation of positive electrode material, affecting the charge-discharge performance of battery.

[0004] Therefore, it is necessary to provide a positive electrode material that can simultaneously improve the cycle performance, rate performance and capacity of the battery. SUMMARY

[0005] The present application provides a kind of positive electrode material, when the positive electrode material is applied to battery, can improve the cycle performance, rate performance and capacity of battery.

[0006] The present application provides a kind of preparation method of positive electrode material, which can prepare the above-mentioned positive electrode material, and the preparation method is simple to operate and suitable for wide application.

[0007] The present application provides a kind of positive electrode sheet, which comprises the above-mentioned positive electrode material, so that the positive electrode sheet can improve the cycle performance, rate performance and capacity of battery when applied to battery.

[0008] The present application provides a kind of battery, which comprises the above-mentioned positive electrode sheet, and the battery has excellent cycle performance, rate performance and capacity.

[0009] The present application provides a kind of electric equipment, which comprises the above-mentioned battery, and the electric equipment has excellent endurance and service life, and excellent market application prospect.

[0010] The present application provides a kind of positive electrode material, wherein the positive electrode material is a single crystal positive electrode material, and the molecular formula of the positive electrode material is shown as formula 1.

[0011] LiNi e Cof Mn g M d O 2-x F x Formula 1

[0012] wherein 0.8≤e≤0.98, 0≤f≤0.1, 0.02≤g≤0.20, 0

[0013] M is selected from at least one of Zr, Ti, Nb, V and Ta.

[0014] The positive electrode material as described above, wherein M is at least selected from at least one of Nb, Ta and V.

[0015] The positive electrode material as described above, wherein the positive electrode material has a (003) crystal face characteristic peak with 2θ of 18.6-18.9° and a (104) crystal face characteristic peak with 2θ of 44.3-44.5° in an X-ray diffraction spectrum of the positive electrode material, and the intensity I 003 of the (003) crystal face characteristic peak satisfies: I 104 / I 003 of the (104) crystal face characteristic peak satisfies: I 104 = 1.440-1.480; and / or,

[0016] The ratio of the cell c-axis length and the a-axis length of the positive electrode material satisfies: c / a = 4.933-4.945.

[0017] The positive electrode material as described above, wherein at least part of the surface of the positive electrode material has fluoride.

[0018] The positive electrode material as described above, wherein the particle size of the positive electrode material is 1-10 μm.

[0019] The positive electrode material as described above, wherein the positive electrode material is prepared by subjecting a positive electrode material precursor, a lithium source and MF y to hydrothermal reaction and sintering treatment; or,

[0020] The positive electrode material is prepared by subjecting a raw material system comprising a nickel source, a manganese source, a lithium source and MF y to hydrothermal reaction and sintering treatment.

[0021] 4≤y≤5.

[0022] The present application provides a preparation method of the positive electrode material as described above, comprising: subjecting a positive electrode material precursor, a lithium source and MF y to hydrothermal reaction and sintering treatment to obtain the positive electrode material; or,

[0023] subjecting a raw material system comprising a nickel source, a manganese source, a lithium source and MF y to a hydrothermal reaction and a sintering treatment to obtain the positive electrode material;

[0024] 4≤y≤5.

[0025] The preparation method as described above, wherein in the hydrothermal reaction, the temperature is 100-200 DEG C, the time is 6-12h, and the temperature rising rate is 2-5 DEG C / min.

[0026] The preparation method as described above, wherein the sintering treatment comprises a first sintering treatment and a second sintering treatment in sequence.

[0027] The temperature of the second sintering treatment is greater than that of the first sintering treatment.

[0028] The preparation method as described above, wherein in the first sintering treatment, the temperature is 400-600 DEG C, and the time is 1-4h; and / or,

[0029] In the second sintering treatment, the temperature is 700-900 DEG C, and the time is 12-16h.

[0030] The application provides a positive electrode sheet, comprising the positive electrode material as described above.

[0031] The application provides a battery, comprising the positive electrode sheet as described above.

[0032] The application provides a power consuming device, comprising the battery as described above.

[0033] The positive electrode material of the application has a special composition, so that when it is applied to a battery, the cycle performance, rate performance and capacity of the battery can be improved.

[0034] The preparation method of the positive electrode material of the application is used for preparing the positive electrode material as described above, and has the advantages of simple operation and low preparation cost.

[0035] The positive electrode sheet of the application comprises the positive electrode material as described above, and when it is applied to a battery, the cycle performance, rate performance and capacity of the battery can be improved.

[0036] The battery of the application comprises the positive electrode sheet as described above, so that the battery has excellent rate performance, cycle performance and capacity, and has a wide application prospect.

[0037] The power consuming device of the application comprises the battery as described above, and has excellent endurance and service life, and an excellent market application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to make the technical solutions in the embodiments of the present application or the related art clearer, the accompanying drawings needed to be used in the description of the embodiments of the present application or the related art are briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0039] Figure 1 SEM image of the positive electrode material in Example 1 of the present application;

[0040] Figure 2 SEM image of the positive electrode material in Example 2 of the present application;

[0041] Figure 3 SEM image of the positive electrode material in Example 3 of the present application;

[0042] Figure 4 SEM image of the positive electrode material in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0043] In order to make the technical solutions in the embodiments of the present application or the related art clearer, the accompanying drawings needed to be used in the description of the embodiments of the present application or the related art are briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0044] The first aspect of the present application provides a positive electrode material, which is a single-crystal positive electrode material, and the molecular formula of the positive electrode material is shown as Formula 1.

[0045] LiNi e Co f Mn g M d O 2-x F x Formula 1

[0046] wherein 0.8≤e≤0.98, 0≤f≤0.1, 0.02≤g≤0.20, 0<d≤0.005, e+f+g+d=1, 0<x≤0.025.

[0047] M is selected from at least one of Zr, Ti, Nb, V and Ta.

[0048] The positive electrode material of the present application is a single crystal positive electrode material, which is a composite metal oxide including at least lithium element, nickel element, manganese element, M element and F element, and in some embodiments, can also include cobalt element. The M element can be selected from at least one of Zr, Ti, Nb, V and Ta.

[0049] In the high-nickel positive electrode material, two hexagonal phases (H2-H3) will cause anisotropic volume expansion at about 4.2V (vs. Li / Li+) to cause serious degradation of the structure of the positive electrode material, resulting in the formation of microcracks between the lattices of the positive electrode material. By doping metal elements and F elements in the bulk phase of the positive electrode material, the present application can inhibit the structural degradation of the positive electrode material and reduce the formation of microcracks. For example, a small amount of metal elements can be doped to replace Ni, Co and Mn, which can effectively alleviate the volume change of the high-nickel positive electrode material when it undergoes phase transition under high voltage conditions. The F element doping mainly replaces the oxygen sites of the positive electrode material, connects the Li layers and improves the stability of the positive electrode material. Further, the use of high-valence cation M ion doping improves the stability of the positive electrode material, thereby improving the cycle performance of the battery. For example, the Ti-O bond has strong bond energy, thereby reducing the average length of the Ni-O bond, improving the strength of the Ni-O bond, alleviating the oxygen defects in the positive electrode material and reducing the Li / Ni mixing of the positive electrode material. At the same time, since the lattice of the M ion is generally larger than that of the transition metal element (Ni, Co, Mn), the doping in the transition metal layer of the positive electrode material will increase the lattice spacing of the positive electrode material, improve the diffusion rate of Li +

[0050] In some embodiments of the present application, M is at least selected from at least one of Nb, Ta and V.

[0051] It can be understood that M is at least selected from at least one of Nb, Ta and V, and can also be simultaneously selected from Zr and / or Ti.

[0052] ​When M is at least selected from at least one of Nb, Ta and V, a +5 valence metal ion can be doped into the positive electrode material, the +5 valence metal ion has a larger radius, can further expand the lattice parameter of the positive electrode material, promote the diffusion of lithium ions, improve the rate performance and capacity of the battery, and as the M-O bond energy formed by the +5 valence metal ion and O is stronger, the stability of the positive electrode material can be further improved, and the cycle performance of the battery is improved.

[0053] In some embodiments of the present application, the positive electrode material has a (003) crystal face characteristic peak with 2theta of 18.6-18.9° and a (104) crystal face characteristic peak with 2theta of 44.3-44.5° in the X-ray diffraction spectrum of the positive electrode material, and the intensity I 003 of the (003) crystal face characteristic peak is greater than the intensity I 104 of the (104) crystal face characteristic peak, and satisfies: I 003 / I 104 =1.440-1.480.

[0054] The X-ray diffraction spectrum (XRD spectrum) of the positive electrode material of the present application has a (003) crystal face characteristic peak with 2theta of 18.6-18.9° and a (104) crystal face characteristic peak with 2theta of 44.3-44.5°, wherein the (003) crystal face characteristic peak is a characteristic peak reflecting the intensity of the (003) crystal face of the ternary material, the (104) crystal face intensity characteristic peak is a characteristic peak reflecting the (104) crystal face of the ternary material, the intensity I 003 of the (003) crystal face characteristic peak is greater than the intensity I 104 of the (104) crystal face characteristic peak, and satisfies: I 003 / I 104 =1.440-1.480.

[0055] When the intensity I 003 of the (003) crystal face characteristic peak is greater than the intensity I 104 of the (104) crystal face characteristic peak in the XRD spectrum of the positive electrode material, it proves that the lithium-nickel mixing of the positive electrode material is lower, which helps to further improve the cycle performance of the battery. Optionally, the value of I 003 / I 104 may be any one of 1.440, 1.441, 1.443, 1.445, 1.447, 1.449, 1.451, 1.453, 1.455, 1.457, 1.459, 1.461, 1.465, 1.471, 1.475 and a range formed by any two of them.

[0056] Further, the cell c-axis length and the a-axis length of the positive electrode material satisfy: c / a=4.933-4.945.

[0057] In the present application, the positive electrode material is subjected to XRD test to obtain the XRD pattern of the positive electrode material. After Rietveld refinement treatment, it can be known that the ratio of the cell c-axis length to the a-axis length of the positive electrode material satisfies: c / a = 4.933-4.945.

[0058] When the ratio of the cell c-axis length to the a-axis length of the positive electrode material satisfies the above range, the interlayer spacing of the positive electrode material is larger, which can better promote the transmission of lithium ions and improve the rate performance and capacity of the battery. Alternatively, c / a can be any one of 4.935, 4.937, 4.939, 4.941, 4.943, 4.945 and a range formed by any two thereof.

[0059] In some embodiments of the present application, at least part of the surface of the positive electrode material has fluoride.

[0060] Exemplarily, the fluoride can be LiF and / or NiF2.

[0061] It can be understood that the entire surface of the positive electrode material can have fluoride, and part of the surface of the positive electrode material can have fluoride. The present application does not particularly limit the content of fluoride on the surface of the positive electrode material. When the surface of the positive electrode material has fluoride, the content of adsorbed oxygen on the surface of the positive electrode material can be reduced, and then the adsorbed oxygen and the Li salt on the surface of the positive electrode material form surface free lithium, reducing the erosion of the electrolyte to the surface of the positive electrode material. Increasing the lithium interlayer spacing of the positive electrode material and reducing the lithium ion migration activation energy are helpful for the deintercalation of lithium ions.

[0062] The inventors found in the research that when the particle size of the positive electrode material is 1-10 μm, the positive electrode material not only has excellent rate performance, but also is not easy to break during long-term cycling, improving the cycle performance of the positive electrode material. Further, the particle size of the positive electrode material is 1-5 μm, and in some embodiments, the particle size of the positive electrode material can be 1-3 μm. The particle size of the positive electrode material refers to the average particle size of the primary particles of the positive electrode material.

[0063] In some embodiments of the present application, the positive electrode material is prepared by subjecting a positive electrode material precursor, a lithium source and MF y to hydrothermal reaction and sintering treatment; or,

[0064] The positive electrode material is prepared by subjecting a raw material system comprising a nickel source, a manganese source, a lithium source and MF y to hydrothermal reaction and sintering treatment;

[0065] 4≤y≤5.

[0066] In the present application, the positive electrode material precursor can be a metal oxide precursor containing nickel and manganese elements, a metal oxide precursor containing nickel, cobalt and manganese elements, a metal hydroxide precursor containing nickel and manganese elements, or a metal hydroxide precursor containing nickel, cobalt and manganese elements commonly used in the art. In some embodiments, the molecular formula of the metal hydroxide precursor can be Ni e Co f Mn g (OH)2(0.8≤e≤0.98, 0≤f≤0.1, 0.02≤g≤0.20, e+f+g=1), the metal hydroxide precursor can be obtained by commercial purchase or synthesized by the co-precipitation method commonly used in the art; the molecular formula of the metal oxide precursor can be Ni e Co f Mn g O2(0.8≤e≤0.98, 0≤f≤0.1, 0.02≤g≤0.20, e+f+g=1), the metal oxide precursor can be obtained by commercial purchase or prepared by the calcination method commonly used in the art.

[0067] The lithium source can be a compound containing lithium elements commonly used in the art, for example, the lithium source can be selected from LiOH and / or Li2CO3. In some embodiments, due to the low sintering temperature of high-nickel ternary single crystal material, the melting point of Li2CO3 is high, and at a lower sintering temperature, the degree of lithiation of the obtained positive electrode material is low, therefore, in order to ensure the electrochemical performance of the positive electrode material, the lithium source can be a mixture of LiOH and Li2CO3, or the lithium source can be LiOH.

[0068] The nickel source can be a compound containing nickel elements commonly used in the art, for example, NiO; the cobalt source can be a compound containing cobalt elements commonly used in the art, for example, CoO; and the manganese source can be a compound containing manganese elements commonly used in the art, for example, MnO.

[0069] The present application can make the positive electrode material precursor, the lithium source and MFy perform hydrothermal reaction, make the Li elements, M elements and F elements enter the positive electrode material precursor, and then perform sintering treatment, thereby obtaining the positive electrode material. The present application can also make at least the raw material system including the nickel source, the manganese source, the lithium source and MFy perform hydrothermal reaction, and then perform sintering treatment, thereby obtaining the positive electrode material including the nickel elements, the manganese elements, the lithium elements, the M elements and the F elements; the present application can also make at least the raw material system including the nickel source, the manganese source, the cobalt source, the lithium source and MFy perform hydrothermal reaction, and then perform sintering treatment, thereby obtaining the positive electrode material including the nickel elements, the manganese elements, the cobalt elements, the lithium elements, the M elements and the F elements.

[0070] In some embodiments, the ratio of the molar content of lithium element in the lithium source to the total molar content of transition metal elements in the positive electrode material precursor can be: Li / (Ni+Co+Mn)=(1.01-1.1):1, further Li / (Ni+Co+Mn)=(1.02-1.08):1, and more further Li / (Ni+Co+Mn)=(1.04-1.06):1. The ratio of the molar content of lithium element in the lithium source to the total molar content of transition metal elements in the nickel source, the manganese source, and the cobalt source can be: Li / (Ni+Co+Mn)=(1.01-1.1):1, further Li / (Ni+Co+Mn)=(1.02-1.08):1, and more further Li / (Ni+Co+Mn)=(1.04-1.06):1.

[0071] MF y The mass of the M element in the positive electrode material precursor accounts for 1000-5000ppm of the total mass of the transition metal elements, further 2000-5000ppm, and more further 2000-3000ppm. MF y The mass of the M element in the nickel source, the manganese source, and the cobalt source accounts for 1000-5000ppm of the total mass of the transition metal elements, further 2000-5000ppm, and more further 2000-3000ppm. When MF y When the mass of the M element and the total mass of the transition metal elements satisfy the above relationship, the positive electrode material shown in Formula 1 can be prepared, and the doping amounts of the M element and the F element are moderate, which can improve the cycle performance and the rate performance of the positive electrode material while ensuring the capacity of the positive electrode material.

[0072] The present application simultaneously dopes metal cations (M ions) and anions (F ions) in the preparation process of the positive electrode material, which can improve the uniformity of the distribution of the metal cations and the anions in the positive electrode material, and will not introduce other impurities in the doping process, thereby improving the electrochemical performance of the positive electrode material.

[0073] The second aspect of the present application provides a preparation method of the positive electrode material of the first aspect, comprising: mixing a positive electrode material precursor, a lithium source, and MF y to obtain the positive electrode material through hydrothermal reaction and sintering treatment; or,

[0074] mixing a raw material system comprising a nickel source, a manganese source, a lithium source, and MF y to obtain the positive electrode material through hydrothermal reaction and sintering treatment;

[0075] 4≤y≤5.

[0076] The preparation method of the positive electrode material of the application is simple in operation and low in preparation cost.

[0077] In some embodiments of the application, when the temperature in the hydrothermal reaction is 100-200 DEG C, the time is 6-12h, and the temperature rising rate is 2-5 DEG C / min, the M element and the F element can be more uniformly doped into the positive electrode material to improve the cycle performance, the rate performance and the capacity of the positive electrode material under the condition of saving energy. Further, in the hydrothermal reaction, the temperature is 100-150 DEG C, and the time is 8-12h.

[0078] In some embodiments, ethanol or water can be used as the solvent in the hydrothermal reaction, wherein the ethanol can more easily dissolve MF y and lithium salt, so further, the solvent can be ethanol.

[0079] In some embodiments, the hydrothermal reaction can include: dissolving the positive electrode material precursor, the lithium source and MF y in ethanol at 25 DEG C, stirring at a speed of 500-1000r / min for 1-3h to obtain a mixed solution; transferring the mixed solution into a reaction kettle, placing the reaction kettle in an oven, setting the temperature of the oven to 100-200 DEG C, the time to 6-12h, and the temperature rising rate to 2-5 DEG C / min, so that the mixed solution is subjected to hydrothermal reaction to obtain a reaction system including an intermediate product; after the hydrothermal reaction is completed, the reaction system including the intermediate product is taken out, the intermediate product in the reaction system including the intermediate product is collected by centrifugation or filtration, the intermediate product is placed in a vacuum drying box for drying treatment after the collection is completed, and then the intermediate product is taken out for grinding treatment to obtain a sintering material.

[0080] Alternatively, dissolving the nickel source, the cobalt source, the manganese source, the lithium source and MF y in ethanol at 25 DEG C, stirring at a speed of 500-1000r / min for 1-3h to obtain a mixed solution; transferring the mixed solution into a reaction kettle, placing the reaction kettle in an oven, setting the temperature of the oven to 100-200 DEG C, the time to 6-12h, and the temperature rising rate to 2-5 DEG C / min, so that the mixed solution is subjected to hydrothermal reaction to obtain a reaction system including an intermediate product; after the hydrothermal reaction is completed, the reaction system including the intermediate product is taken out, the intermediate product in the reaction system including the intermediate product is collected by centrifugation or filtration, the intermediate product is placed in a vacuum drying box for drying treatment after the collection is completed, and then the intermediate product is taken out for grinding treatment to obtain a sintering material.

[0081] Further, in order to prevent MF y from volatilizing, the formation process of the mixed solution can be carried out in a sealed container;

[0082] In the stirring treatment, the rotating speed can be 600-800 r / min, and the time can be 2-3 h.

[0083] In the drying treatment, the temperature is 50-100℃, and the time is 1-6 h; further, in the drying treatment, the temperature is 60-80℃, and the time is 3-5 h.

[0084] The sintering treatment is not particularly limited in the present application, and can be a sintering treatment commonly used in the art, for example, one sintering treatment, two sintering treatments or even more sintering treatments can be performed. In some embodiments of the present application, the sintering treatment comprises a first sintering treatment and a second sintering treatment in sequence, and the temperature of the second sintering treatment is higher than that of the first sintering treatment. By two sintering treatments and the temperature of the second sintering treatment being higher than that of the first sintering treatment, the raw material can be sintered more sufficiently in the case of saving energy, so that the positive electrode material with excellent cycle performance, rate performance and capacity is obtained.

[0085] In some embodiments of the present application, when the temperature is 400-600℃ and the time is 1-4 h in the first sintering treatment; and / or,

[0086] When the temperature is 700-900℃ and the time is 12-16 h in the second sintering treatment, the M element and the F element can enter the crystal lattice of the positive electrode material more sufficiently and uniformly, so that the cycle performance, rate performance and capacity of the positive electrode material are improved.

[0087] Further, the temperature is 450-550℃ and the time is 2-4 h in the first sintering treatment; and the temperature is 750-850℃ and the time is 12-16 h in the second sintering treatment.

[0088] Further, the temperature is 500-550℃ and the time is 2-4 h in the first sintering treatment; and the temperature is 750-800℃ and the time is 12-16 h in the second sintering treatment.

[0089] In the present application, the atmosphere of the sintering treatment can be oxygen. In some embodiments, the sintering treatment is followed by a gas crushing treatment to obtain a positive electrode material with a target particle size; wherein the environment of the gas crushing treatment is a water-free environment, and the dew point temperature can be -20℃ to -50℃, further, the dew point temperature can be -30℃ to -50℃, and further, the dew point temperature can be -40℃ to -50℃; in the gas crushing treatment, the gas is compressed air, and further, the gas is compressed nitrogen; the pressure can be 0.1 MPa to 0.8 MPa, further, the pressure can be 0.2 MPa to 0.6 MPa, and further, the pressure can be 0.2 MPa to 0.4 MPa.

[0090] The third aspect of the present application provides a positive electrode sheet, wherein the positive electrode sheet comprises the positive electrode material of the first aspect.

[0091] In the present application, the positive electrode sheet further comprises a positive electrode active layer and a positive electrode current collector. In a specific embodiment, the positive electrode material, the binder and the conductive agent are prepared into a positive electrode slurry, and then the positive electrode slurry is arranged on at least part of the surface of the positive electrode current collector. After drying, the positive electrode sheet comprising the positive electrode active layer is obtained.

[0092] The positive electrode sheet of the present application has excellent cycle performance, rate capability and capacity due to the positive electrode material of the first aspect.

[0093] The fourth aspect of the present application provides a battery comprising the positive electrode sheet of the third aspect.

[0094] It can be understood that the battery further comprises a separator, a negative electrode sheet, an electrolyte and an outer package. In the present application, the positive electrode sheet, the separator and the negative electrode sheet are stacked to form an electrode assembly with a stacking structure, and then the electrode assembly is placed in the outer package. The electrolyte is injected into the outer package, and after sealing and formation, the battery is obtained. Alternatively, the positive electrode sheet, the separator and the negative electrode sheet are stacked, and then a winding treatment is performed to form an electrode assembly with a winding structure. Then the electrode assembly is placed in the outer package, the electrolyte is injected into the outer package, and after sealing and formation, the battery is obtained.

[0095] The battery of the present application has excellent rate capability, cycle performance and capacity due to the positive electrode sheet of the third aspect, and has a wide application prospect.

[0096] The fifth aspect of the present application provides an electrical equipment comprising the battery of the fourth aspect.

[0097] The electrical equipment of the present application has excellent endurance and service life due to the battery of the fourth aspect, and has an excellent market application prospect.

[0098] Hereinafter, the scheme of the present application will be described in detail through specific embodiments.

[0099] Example 1

[0100] The battery of the present embodiment is prepared by a method comprising the following steps:

[0101] 1) Preparation of the positive electrode material

[0102] a. The positive electrode material precursor Ni 0.9 Co 0.05 Mn 0.05The (OH) 2, ZrF 4 and LiOH are sequentially poured into a sealed container with anhydrous ethanol, and a magnetic stirrer is used for stirring treatment to obtain a mixed solution; the mixed solution is transferred into a reaction kettle, and the reaction kettle is placed in an oven for hydrothermal reaction to obtain a reaction system including an intermediate product; the reaction system including the intermediate product is taken out, the intermediate product is centrifuged and collected, and the intermediate product is placed in an oven for drying treatment; after the drying is completed, a mortar is used for grinding to obtain a sintering material;

[0103] The mass of the Zr element in the ZrF 4 accounts for 2000 ppm in the total mass of the transition metal elements in the positive electrode material precursor, and the ratio of the molar content of lithium in the lithium hydroxide to the total molar content of the transition metal elements in the positive electrode material precursor is 1.04:1.

[0104] In the stirring treatment, the rotating speed is 600 r / min, and the time is 2 h.

[0105] In the hydrothermal reaction, the temperature is 150 DEG C, the time is 12 h, and the temperature rising rate is 3 DEG C / min.

[0106] In the drying treatment, the temperature is 80 DEG C, and the time is 4 h.

[0107] The specific parameters of the positive electrode material are shown in Table 1.

[0108] b. The sintering material is placed in a tube furnace for solid-phase sintering treatment, the sintering condition is oxygen environment, after the sintering is completed, gas crushing treatment is carried out in anhydrous environment (dew point is -40 DEG C), and the positive electrode material is obtained.

[0109] The sintering treatment includes first sintering treatment and second sintering treatment in sequence; in the first sintering treatment, the temperature is 500 DEG C, and the time is 3 h; in the second sintering treatment, the temperature is 800 DEG C, the time is 14 h, and the temperature rising rate is 5 DEG C / min.

[0110] In the gas crushing treatment, the gas is compressed nitrogen, and the pressure is 0.3 MPa.

[0111] 2) Preparation of the positive electrode sheet

[0112] N-methyl pyrrolidone is used as a solvent, the binder PVDF, the conductive agent acetylene black and the positive electrode material are dissolved in the solvent to obtain a positive electrode slurry, the positive electrode slurry is uniformly coated on two surfaces of an aluminum foil and vacuum dried to obtain a positive electrode sheet including a positive electrode active layer.

[0113] In the positive electrode active layer, the mass ratio of the positive electrode material, the binder and the conductive agent is 90:5:5.

[0114] 3) Preparation of the battery

[0115] In a glove box, the positive electrode sheet obtained after cutting and pressing, the polypropylene microporous diaphragm, the lithium sheet negative electrode, the negative electrode shell, the positive electrode shell, and the gasket are assembled in the order of the negative electrode shell, the gasket, the lithium sheet negative electrode, the diaphragm, the positive electrode sheet, and the positive electrode shell to obtain an electrode assembly, the electrode assembly is placed in an aluminum plastic film, an electrolyte is injected into the aluminum plastic film, and a CR2016 button cell is obtained after sealing and formation.

[0116] In the electrolyte, ethylene carbonate and methyl ethyl carbonate are mixed in a volume ratio of 3:7, and LiPF6 is added, and the concentration of LiPF6 is 1 mol / L.

[0117] Example 2

[0118] The preparation method of the battery of this embodiment is basically the same as that of Example 1, except that:

[0119] 1) Preparation of the positive electrode material

[0120] NbF5 is used to replace ZrF4.

[0121] Example 3

[0122] The preparation method of the battery of this embodiment is basically the same as that of Example 1, except that:

[0123] 1) Preparation of the positive electrode material

[0124] The raw material also includes TaF5, and the mass of Ta element in TaF5 accounts for 2000 ppm of the total mass of transition metal elements in the positive electrode material precursor.

[0125] Example 4

[0126] The preparation method of the battery of this embodiment is basically the same as that of Example 1, except that:

[0127] 1) Preparation of the positive electrode material

[0128] The amount of ZrF4 added in the raw material is changed to the mass of Zr element accounting for 1000 ppm of the total mass of transition metal elements in the positive electrode material precursor.

[0129] Example 5

[0130] The preparation method of the battery of this embodiment is basically the same as that of Example 1, except that:

[0131] 1) Preparation of the positive electrode material

[0132] The raw material also includes TaF5, and the mass of Ta element in TaF5 accounts for 3000 ppm of the total mass of transition metal elements in the positive electrode material precursor.

[0133] Example 6

[0134] The preparation method of the battery of this example is basically the same as that of Example 1, except that:

[0135] 1) Preparation of the positive electrode material

[0136] TaF5 is used to replace ZrF4, and the mass of Ta element in TaF5 accounts for 3000 ppm of the total mass of transition metal elements in the positive electrode material precursor.

[0137] Example 7

[0138] The preparation method of the battery of this example is basically the same as that of Example 1, except that:

[0139] 1) Preparation of the positive electrode material

[0140] TaF5 is used to replace ZrF4, and the mass of Ta element in TaF5 accounts for 5000 ppm of the total mass of transition metal elements in the positive electrode material precursor.

[0141] Comparative Example 1

[0142] The preparation method of the battery of this example is basically the same as that of Example 1, except that:

[0143] 1) Preparation of the positive electrode material

[0144] The positive electrode material precursor Ni 0.9 Co 0.05 Mn 0.05 (OH)2, LiOH is mixed uniformly by a high-speed mixer to obtain a sintering material.

[0145] Comparative Example 2

[0146] The preparation method of the battery of this example is basically the same as that of Example 1, except that:

[0147] 1) Preparation of the positive electrode material

[0148] The positive electrode material precursor Ni 0.9 Co 0.05 Mn 0.05 (OH)2, LiOH, ZrO2 is mixed uniformly by a high-speed mixer to obtain a sintering material. The mass of Zr element accounts for 2000 ppm of the total mass of transition metal elements in the positive electrode material precursor.

[0149] Comparative Example 3

[0150] The preparation method of the battery of this example is basically the same as that of Example 1, except that:

[0151] 1) Preparation of the positive electrode material

[0152] The positive electrode material precursor Ni 0.9 Co 0.05 Mn 0.05 (OH)2, LiOH were mixed uniformly by a high-speed mixer to obtain a sintering material. The single-crystal ternary positive electrode material LiNi 0.9 Co 0.05 Mn 0.05 O2 was prepared. Then the positive electrode material was placed in a tube furnace, NH4F was introduced, the sintering temperature was set to 450℃, and the temperature was kept for 6h to obtain F-doped LiNi 0.9 Co 0.05 Mn 0.05 O 2-x F x .

[0153] Comparative Example 4

[0154] The preparation method of the battery of the present comparative example is basically the same as that of Example 1, except that:

[0155] 1) Preparation of the positive electrode material

[0156] The positive electrode material precursor Ni 0.9 Co 0.05 Mn 0.05 (OH)2, LiOH, MgO were mixed uniformly by a high-speed mixer to obtain a sintering material. The mass of the Mg element in the total mass of the transition metal elements in the positive electrode material precursor accounted for 2000ppm.

[0157] Performance test

[0158] The positive electrode materials and batteries in the examples and comparative examples were respectively subjected to the following performance tests, and the test results are shown in Table 1 and Table 2, respectively;

[0159] 1. SEM test

[0160] A Zeiss scanning electron microscope (GeminiSEM 300) was used to observe the surface morphology of the positive electrode material.

[0161] Figure 1 SEM image of the positive electrode material in Example 1 of the present application; Figure 2 SEM image of the positive electrode material in Example 2 of the present application; Figure 3 SEM image of the positive electrode material in Example 3 of the present application; Figure 4 SEM image of the positive electrode material in Comparative Example 1 of the present application. As Figures 1-4 It can be seen that the particle size of the positive electrode material in the examples of the present application is large and the particle size distribution is more uniform, which helps to improve the rate performance and cycle performance of the battery.

[0162] 2. XRD test

[0163] The XRD test of the positive electrode material was performed by using Broker D8 X-ray diffractometer (Broker AXSD8 Advance), and the XRD pattern of the positive electrode material was obtained, and the I 003 / I 104 The Rietveld refinement processing was performed on the XRD pattern of the positive electrode material to obtain the cell c-axis length and the a-axis length of the positive electrode material, and the results are shown in Table 1.

[0164] In the XRD test, the light source was The test 2θ angle was from 10-90° with 0.5° / step.

[0165] 3. Residual alkali test

[0166] The test method of the residual alkali value was as follows: 5 g of the positive electrode material was weighed, added into 50 mL of carbon dioxide-removed ultrapure water, dissolved in a beaker, and ultrasonically oscillated at an ultrasonic frequency of 5 KHz and a power of 50 W for 5 min, and stirred every 1 min during the ultrasonic oscillation; then, the mixed solution obtained by ultrasonic oscillation was filtered into a 100 mL volumetric flask with a quantitative filter paper, and the volume was made up to the mark, and the filtrate volume was recorded. Finally, the above sample solution was titrated with a hydrochloric acid standard solution, and the volumes V1 and V2 of the consumed hydrochloric acid standard solution were recorded, wherein V1 was the volume of the hydrochloric acid standard solution consumed for titration to the first jump point, and V2 was the volume of the hydrochloric acid standard solution consumed for titration from the first jump point to the second jump point. According to formula (1) and formula (2), the OH - and CO3 2- The residual alkali value:

[0167]

[0168] In formula (1) and formula (2), m—actual mass of the sample, g;

[0169] m—actual mass of the sample, g;

[0170] c—concentration of the hydrochloric acid standard solution, 12 mol / L;

[0171] V1—volume of the hydrochloric acid standard solution consumed for titration to the first jump point, mL;

[0172] V2—volume of the hydrochloric acid standard solution consumed for titration from the first jump point to the second jump point, mL;

[0173] V3—volume of the filtrate, mL;

[0174] V4—volume of the filtrate after constant volume, 100 mL;

[0175] w(OH - —OH - residual base value, wt. %;

[0176] w(CO3 2- —CO3 2- residual base value, wt. %.

[0177] 4. Electrochemical performance test

[0178] The electrochemical test of the button cell uses the button cell test channel of Neware, and all the electrochemical test temperatures are 25℃ in air environment. The specific results are shown in Table 3;

[0179] The test conditions used in the capacity test are that the test window is 2.5-4.3V, the charging current is 0.1C, the constant voltage charging at 4.3V is cut off at the current of 0.01C, the discharging current is 0.1C, and the average value is taken after two cycles;

[0180] The charging and discharging current in the cycle test is 1C, and the test window is 2.5-4.3V;

[0181] The rate test condition is that the charging current is 0.2C, the constant voltage charging at 4.3V is cut off at the current of 0.01C, and the discharging is carried out at 0.2C, 0.5C, 1C, 2C and 5C respectively to 2.5V.

[0182] Table 1

[0183]

[0184]

[0185] The metal fluoride volatilizes in the preparation process, and it is difficult to accurately quantify. The content x of F element in the examples and the comparative examples satisfies: 0 < x ≤ 0.025; when the positive electrode material contains F element, the F element will replace O element, so the content of O element is 2-x. The positive electrode material in the examples and the comparative examples of the application can improve the performance of the battery as long as it contains F element, and the accurate quantification of F element has little effect on the performance of the battery.

[0186] As can be seen from Table 1, the c / a value of the positive electrode material in the examples of the application is larger, which proves that the layered structure of the positive electrode material in the examples is better, which helps to improve the rate performance of the battery; the I 003 / I 104 value of the positive electrode material in the examples is also larger, which indicates that the lithium-nickel mixing of the positive electrode material in the examples is lower, which helps to improve the cycle performance of the battery.

[0187] Table 2

[0188] Surface LiOH (ppm) Surface Li2CO3 (ppm) Example 1 4101 7901 Example 2 3635 7793 Example 3 3522 7754 Example 4 4781 8802 Example 5 3405 7628 Example 6 3722 7785 Example 7 3387 7595 Comparative Example 1 5039 9029 Comparative Example 2 5032 8977 Comparative Example 3 4587 8214 Comparative Example 4 5044 9101

[0189] As can be seen from Table 2, the surface free lithium content of the positive electrode material in the embodiment of the present application is lower than that of the comparative example, and the free lithium content is further reduced with the increase of the F doping amount, which indicates that the F doping replaces the O site, forms LiF on part of the surface, reduces the generation of surface free lithium, and improves the environmental stability of the material.

[0190] Table 3

[0191]

[0192] As can be seen from Table 3, the positive electrode material in the embodiment of the present application has more excellent cycle performance and rate performance, which indicates that by including the metal element M and the F element in the positive electrode material, the stability of the positive electrode material can be improved without affecting the capacity of the battery, the interlayer spacing of the positive electrode material is expanded, and thus the cycle performance and rate performance of the battery are improved.

[0193] Specifically, in Example 1, the Zr element is doped into the transition metal layer, and the F element is doped into the O layer. The Zr ion radius is large, which expands the lattice parameters of the positive electrode material, is beneficial to the diffusion of lithium ions, and improves the rate performance of the battery. During the charging / discharging process, the Zr 4+ The valence state of the support column is unchanged, and the Zr-O bond with stronger bond energy can stabilize the structure of the positive electrode material. The F has stronger bond energy with the metal, which improves the stability of the positive electrode material and increases the Li layer spacing, thereby improving the rate performance of the positive electrode material; in Example 2, the Nb element has a valence of +5, and more F elements are doped, which improves more modification sites of the positive electrode material. Similarly, the Nb is doped into the transition metal layer, the Nb-O bond energy is stronger, which improves the stability of the positive electrode material, and further improves the cycle performance of the battery; in Example 3, the Zr is doped into the transition metal element layer, which plays a supporting role and stabilizes the structure of the positive electrode material; the Ta element is partially inclined to the Li site, which reduces the lithium-nickel mixing. The F element is also located at the O site, which increases the Li layer spacing and stabilizes the structure of the positive electrode material.

[0194] Further, as can be seen from Example 1 and Example 2, when the M element includes at least one of Nb, Ta and V, the cycle performance and rate performance of the battery can be significantly improved;

[0195] As can be seen from Example 3 and Example 5, by further satisfying the ratio of the cell c-axis length to the a-axis length of the positive electrode material to be 4.933-4.945, the capacity and cycle performance of the battery can be further improved.

[0196] As can be seen from Example 6 and Example 7, by further satisfying the intensity I 003 and the intensity I 104By selection, the cycle performance and the rate performance of the battery can be obviously improved while the capacity of the battery is guaranteed to be excellent.

[0197] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A positive electrode material, characterized by, The positive electrode material is a single-crystal positive electrode material, and a molecular formula of the positive electrode material is shown as Formula 1. LiNi e Co f Mn g M d O 2-x F x Formula 1 Wherein, 0.8≤e≤0.98, 0≤f≤0.1, 0.02≤g≤0.20, 0<d≤0.005, e+f+g+d=1, 0<x≤0.

025. M is Zr, V and / or Ta.

2. The positive electrode material of claim 1, wherein, The positive electrode material has a (003) crystal face characteristic peak with 2θ of 18.6-18.9° and a (104) crystal face characteristic peak with 2θ of 44.3-44.5° in the X-ray diffraction pattern, the intensity I 003 of the (003) crystal face characteristic peak satisfies: 104 I 003 (003) / I 104 = 1.440-1.480; and / or, A ratio of a cell c-axis length to an a-axis length of the positive electrode material satisfies: c / a=4.933-4.

945.

3. The positive electrode material according to claim 1 or 2, characterized in that, At least part of a surface of the positive electrode material has fluoride.

4. The positive electrode material according to claim 1 or 2, characterized in that, The particle size of the positive electrode material is 1-10 μm.

5. The positive electrode material of claim 3, wherein, The particle size of the positive electrode material is 1-10 μm.

6. The cathode material of any one of claims 1, 2, 5, wherein, The positive electrode material is prepared by subjecting a positive electrode material precursor, a lithium source and MF y hydrothermal reaction and sintering treatment; or, The positive electrode material is prepared by hydrothermal reaction and sintering treatment of a raw material system comprising a nickel source, a manganese source, a lithium source, and MF y ​ 4≤y≤5。 7. The cathode material of claim 3, wherein, The positive electrode material is prepared by subjecting a positive electrode material precursor, a lithium source and MF y by hydrothermal reaction and sintering treatment; or, The positive electrode material is prepared by hydrothermal reaction and sintering treatment of a raw material system comprising a nickel source, a manganese source, a lithium source, and MF y ​ 4≤y≤5。 8. The positive electrode material of claim 4, wherein, The positive electrode material is prepared by subjecting a positive electrode material precursor, a lithium source and MF y by hydrothermal reaction and sintering treatment; or, The positive electrode material is prepared by hydrothermal reaction and sintering treatment of a raw material system comprising a nickel source, a manganese source, a lithium source, and MF y ​ 4≤y≤5。 9. A method for producing the positive electrode material according to any one of claims 1 to 8, characterized by, Comprising: The positive electrode material precursor, a lithium source and MF y The positive electrode material is obtained by performing a hydrothermal reaction and a sintering treatment. Or, subjecting a raw material system comprising a nickel source, a manganese source, a lithium source, and MF y to a hydrothermal reaction and a sintering treatment to obtain the positive electrode material; 4≤y≤5。 10. The method of claim 9, wherein, In the hydrothermal reaction, the temperature is 100-200℃, the time is 6-12h, and the temperature rising rate is 2-5℃ / min.

11. The production method according to claim 9 or 10, characterized by, The sintering treatment comprises a first sintering treatment and a second sintering treatment in sequence. The temperature of the second sintering treatment is greater than the temperature of the first sintering treatment.

12. The method of claim 11, wherein, In the first sintering treatment, the temperature is 400-600℃, and the time is 1-4h; and / or, In the second sintering treatment, the temperature is 700-900℃, and the time is 12-16h.

13. A positive electrode sheet characterized by comprising: The positive electrode material of any one of claims 1-8.

14. A battery, characterized by The positive electrode sheet of claim 13.

15. An electrical device, characterized by The battery of claim 14.

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