Positive electrode material and preparation method thereof, battery and electrical device

Abstract

The present invention discloses a positive electrode material and a preparation method thereof, a battery, and an electrical device. The preparation method of the positive electrode material comprises: preparing a first colloidal solution, the first colloidal solution comprising water, a thickener, and transition metal ions; preparing a lithium salt solution; pouring the lithium salt solution into the first colloidal solution to form a gel-like material; drying the gel-like material to obtain a precursor; and calcining the precursor to obtain the positive electrode material. According to the preparation method of the positive electrode material of the present invention, by adding a thickener to prepare a first colloidal solution comprising multiple transition metal ions, and then pouring the lithium salt solution into the colloidal solution to form a gel-like material, the viscosity of the solution can be increased, making the particle growth rate easier to control; and by controlling the particle growth rate, the crystal phase structure of the generated positive electrode material can be improved, microcracks can be reduced, and the cycle performance of the battery can be improved.

Description

Technical Field

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

[0002] The synthesis process for preparing positive electrode materials in related technologies requires monitoring too many conditions, making control difficult. Furthermore, batteries using positive electrode materials prepared using these methods often suffer from poor cycling performance. Therefore, improvements are needed. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a method for preparing a positive electrode material. By adding a thickener to prepare a first colloidal solution containing multiple transition metal ions, and then pouring a lithium salt solution into the first colloidal solution to form a gel-like material, the viscosity of the solution can be increased, making the particle growth rate easier to control. Furthermore, by controlling the particle growth rate, the resulting positive electrode material can have a good crystalline structure, reduce microcracks, and improve battery cycle performance.

[0004] The present invention also provides a positive electrode material prepared using the preparation method of the positive electrode material.

[0005] The present invention also provides a battery having the positive electrode material.

[0006] The present invention also provides an electrical device having the battery.

[0007] According to the first aspect of the present invention, the method for preparing a positive electrode material includes: preparing a first colloidal solution, wherein the first colloidal solution contains water, a thickener, and transition metal ions, wherein the transition metal ions include first transition metal ions, second transition metal ions, and third transition metal ions; preparing a lithium salt solution; pouring the lithium salt solution into the first colloidal solution to form a gel-like material; drying the gel-like material to obtain a precursor; and calcining the precursor to obtain the positive electrode material.

[0008] According to the method for preparing the positive electrode material of an embodiment of the present invention, a thickener is added to prepare a first colloidal solution containing multiple transition metal ions, and then a lithium salt solution is poured into the colloidal solution to form a gel-like material. This can increase the viscosity of the solution and make the particle growth rate easier to control. Moreover, by controlling the particle growth rate, the crystal phase structure of the generated positive electrode material can be improved, microcracks can be reduced, and the battery cycle performance can be better.

[0009] According to some embodiments of the present invention, preparing the first colloidal solution includes: mixing a thickener with water and stirring to form a second colloidal solution; preparing a metal salt solution containing the transition metal ions; mixing the metal salt solution with the second colloidal solution and stirring to form the first colloidal solution.

[0010] According to some embodiments of the present invention, the thickener accounts for 0.05 wt % to 0.15 wt % in the second colloidal solution.

[0011] According to some embodiments of the present invention, the stirring to form the second colloidal solution includes: stirring at a first stirring speed for a first preset time, gradually increasing the stirring speed to a second stirring speed, and stirring at the second stirring speed for a second preset time, wherein the second preset time is greater than the first preset time.

[0012] According to some embodiments of the present invention, the first stirring speed ranges from 180 rpm to 220 rpm, and the second stirring speed ranges from 500 rpm to 700 rpm; and / or, the first stirring time ranges from 3 min to 8 min, and the second stirring time ranges from 45 min to 75 min.

[0013] According to some embodiments of the present invention, the stirring to form the first colloidal solution includes: stirring at a third stirring speed for a third preset time, the third stirring speed ranges from 500 rpm to 700 rpm, and the third preset time ranges from 3 min to 8 min.

[0014] According to some embodiments of the present invention, preparing a metal salt solution containing the transition metal ions includes: weighing a soluble salt of a first transition metal, a soluble salt of a first transition metal, and a soluble salt of a first transition metal according to a stoichiometric ratio, and dissolving them in water to form the metal salt solution.

[0015] According to some embodiments of the present invention, the soluble salt of the first transition metal includes at least one of nickel sulfate, nickel acetate, nickel nitrate and nickel chloride, the soluble salt of the second transition metal includes at least one of cobalt sulfate, cobalt acetate, cobalt nitrate and cobalt chloride, and the soluble salt of the third transition metal includes at least one of manganese sulfate, manganese acetate, manganese nitrate and manganese chloride.

[0016] According to some embodiments of the present invention, the concentration of the metal salt solution ranges from 1 mol / L to 2 mol / L.

[0017] According to some embodiments of the present invention, drying the gel-like material includes drying at a set drying temperature, wherein the set drying temperature ranges from 70° C. to 90° C.

[0018] According to some embodiments of the present invention, calcining the precursor includes: sintering at a first calcination temperature for a first calcination time under an oxygen atmosphere, then heating to a second calcination temperature, and sintering at the second calcination temperature for a second calcination time, wherein the second calcination time is greater than the first calcination time.

[0019] According to some embodiments of the present invention, the first calcination temperature ranges from 400°C to 500°C, and the second calcination temperature ranges from 800°C to 900°C; and / or the first calcination time ranges from 4h to 6h, and the second calcination time ranges from 10h to 14h.

[0020] According to some embodiments of the present invention, preparing the lithium salt solution includes: dissolving a lithium salt in water to form the lithium salt solution; wherein the lithium salt includes at least one of lithium hydroxide, lithium carbonate, lithium chloride, lithium nitrate, lithium acetate and lithium oxalate.

[0021] According to some embodiments of the present invention, the thickener includes at least one of carboxymethyl cellulose, alginic acid, konjac glucomannan, xanthan gum, carrageenan, locust bean gum and guar gum; and / or the first transition metal ion is nickel ion, the second transition metal ion is cobalt ion, and the third transition metal ion is manganese ion or aluminum ion.

[0022] According to the positive electrode material of the second embodiment of the present invention, the positive electrode material is prepared by the preparation method of the first embodiment of the present invention, and the positive electrode material has a single crystal structure and the chemical formula of the positive electrode material is LiNi x Co y Mn z O2, where 0 <x<1,0<y<1,0<z<1,x+y+z=1。

[0023] According to the positive electrode material of the embodiment of the present invention, a preparation method according to the embodiment of the first aspect of the present invention is used. A thickener is added during the preparation to prepare a first colloidal solution containing multiple transition metal ions, and then a lithium salt solution is poured into the colloidal solution to form a gel-like material. This makes the lithium-nickel mixing rate of the positive electrode material low, can reduce microcracks, and the produced positive electrode material has better cycle performance.

[0024] The battery according to the embodiment of the third aspect of the present invention is characterized in that it includes: a battery shell; an electrode group, which is arranged in the battery shell and includes stacked positive and negative electrode sheets, the positive electrode sheet includes a positive electrode collector and a positive electrode active material layer coated on the positive electrode collector, and the positive electrode active material layer includes the positive electrode material according to the embodiment of the second aspect of the present invention.

[0025] The battery according to the embodiment of the present invention includes the positive electrode material according to the embodiment of the second aspect of the present invention. The positive electrode material has a good crystal phase structure, can reduce microcracks, and has better cycle performance of the lithium battery.

[0026] An electrical device according to an embodiment of a fourth aspect of the present invention is characterized by comprising: a battery according to an embodiment of the third aspect of the present invention.

[0027] The electrical device according to the embodiment of the present invention includes the battery according to the embodiment of the third aspect of the present invention, so the battery has better cycle performance and longer life.

[0028] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0030] Figure 1 1 and 2. The XRD patterns of the positive electrode materials prepared by the preparation methods of some embodiments of the present invention are as follows: (a) is the full XRD spectrum of Example 1, Example 2 and Example 3, (b) is the (006) / (102) diffraction peak regional spectrum of Example 1, Example 2 and Example 3, (c) is the (018) / (110) diffraction peak regional spectrum of Example 1, Example 2 and Example 3, (d), (e) and (f) are the XRD refined spectra of Example 1, Example 2 and Example 3, respectively;

[0031] Figure 2 are SEM images of cathode materials prepared according to the preparation methods of some embodiments of the present invention, wherein (a) and (d) are from Example 1, (b) and (e) are from Example 2, and (c) and (f) are from Example 3;

[0032] Figure 3 This is an XPS spectrum of the positive electrode material of Example 2 subjected to an X-ray photoelectron spectroscopy (XPS) test;

[0033] Figure 4 The cathode material of Example 2 is characterized by TEM, selected area electron diffraction (SEAD), and EDS mapping, wherein (a) is a TEM image, (b) is a magnified TEM image, (c) is an FFT image, (d) and (e) are IFFT images, (f) is a mapping image, and (g) is a selected area electron diffraction image.

[0034] Figure 5These are cross-sectional SEM images of the button batteries in Example 2 and Comparative Example 1 after 200 cycles, where (a) and (b) are from Example 2, and (c) and (d) are from Comparative Example 1;

[0035] Figure 6 Graphs showing the electrochemical performance of cathode materials prepared according to the preparation methods of some embodiments of the present invention and cathode materials prepared in related technologies. DETAILED DESCRIPTION

[0036] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0037] The following describes a method for preparing a positive electrode material according to an embodiment of the present invention.

[0038] The method for preparing a positive electrode material according to the first embodiment of the present invention includes:

[0039] A first colloidal solution is prepared, comprising water, a thickener, and transition metal ions. By adding the thickener to the first colloidal solution, the first colloidal solution can be made colloidal and have increased viscosity, thereby making it easier to control the growth rate of the crystal particles.

[0040] For example, the prepared positive electrode material is a ternary positive electrode material, and the transition metal ions include three transition metal ions.

[0041] The transition metal ions include a first transition metal ion, a second transition metal ion, and a third transition metal ion. For example, the first transition metal ion may be a nickel ion, the second transition metal ion may be a cobalt ion, and the third transition metal ion may be a manganese ion. For another example, the first transition metal ion may be a nickel ion, the second transition metal ion may be a cobalt ion, and the third transition metal ion may be an aluminum ion. By premixing multiple transition metal ions, the transition ions can be more fully and evenly dispersed.

[0042] preparing a lithium salt solution, for example, the lithium salt may be lithium hydroxide, lithium carbonate, etc.;

[0043] The lithium salt solution is poured into the first colloidal solution to form a gel-like material.

[0044] The gel-like material is dried to obtain a precursor.

[0045] The precursor is calcined to obtain the positive electrode material.

[0046] According to the method for preparing the positive electrode material of an embodiment of the present invention, a thickener is added to prepare a first colloidal solution containing multiple transition metal ions, and then a lithium salt solution is poured into the colloidal solution to form a gel-like material. This can increase the viscosity of the solution and make the particle growth rate easier to control. Moreover, by controlling the particle growth rate, the crystal phase structure of the generated positive electrode material can be improved, microcracks can be reduced, and the battery cycle performance can be better.

[0047] According to some embodiments of the present invention, preparing a first colloidal solution includes:

[0048] mixing the thickener with water and stirring to form a second colloidal solution;

[0049] By mixing a thickener with water to prepare a second colloidal solution, the viscosity of the second colloidal solution can be increased, thereby increasing the viscosity of the first colloidal solution subsequently prepared using the second colloidal solution, making the growth rate of the particles easier to control;

[0050] A metal salt solution containing transition metal ions is prepared. The metal salt solution includes a first transition metal ion, a second transition metal ion, and a third transition metal ion.

[0051] The metal salt solution and the second colloidal solution are mixed and stirred to form a first colloidal solution.

[0052] According to some embodiments of the present invention, the mass proportion of the thickener in the second colloidal solution is 0.05wt% to 0.15wt%. For example, the mass proportion of the thickener in the second colloidal solution can be 0.05wt%, 0.07wt%, 0.10wt%, 0.12wt%, 0.15wt%, etc. By ensuring that the mass proportion of the thickener in the second colloidal solution is not less than 0.05wt%, the concentration of the thickener is not too low, and the thickener is sufficient to achieve the effect of increasing viscosity. By ensuring that the mass proportion of the thickener in the second colloidal solution is not greater than 0.15wt%, the concentration of the thickener is not too high, avoiding excessive viscosity of the solution and reduced yield.

[0053] According to some embodiments of the present invention, stirring to form a second colloidal solution includes: stirring at a first stirring speed for a first preset time, then gradually increasing the stirring speed to a second stirring speed, and stirring at the second stirring speed for a second preset time, wherein the second preset time is greater than the first preset time. Thickeners are difficult to dissolve in water. By first stirring at the first stirring speed for the first preset time, wherein the first stirring speed is less than the second stirring speed, and the second preset time is greater than the first preset time, the thickener can be fully dissolved first; and by subsequently increasing the stirring speed and stirring at the second stirring speed for the second preset time, the thickener can be fully dispersed, thereby improving the efficiency of preparing the second colloidal solution.

[0054] According to some embodiments of the present invention, the first stirring speed ranges from 180 rpm to 220 rpm, and the second stirring speed ranges from 500 rpm to 700 rpm. For example, the first stirring speed may be 180 rpm, 190 rpm, 200 rpm, 210 rpm, 220 rpm, etc., and the second stirring speed may be 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, etc. By making the first stirring speed not less than 180 rpm, the thickener can be fully dissolved in water and the dissolution rate of the thickener can be accelerated; by making the first stirring speed not higher than 220 rpm, the difficulty of stirring caused by the low initial solubility of the thickener can be avoided. By making the second stirring speed not less than 500 rpm, the thickener can be fully dissolved and dispersed in water to form a uniform and stable second colloidal solution; by making the second stirring speed not higher than 700 rpm, performance can be saved while ensuring that the thickener can be fully dispersed.

[0055] According to some embodiments of the present invention, the first stirring time ranges from 3 minutes to 8 minutes, and the second stirring time ranges from 45 minutes to 75 minutes. For example, the first stirring time can be 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, etc., and the second stirring time can be 45 minutes, 55 minutes, 65 minutes, 75 minutes, etc. By making the first stirring time shorter than the second stirring time, the thickener can be fully dissolved and then dispersed fully and efficiently.

[0056] According to some embodiments of the present invention, stirring to form a first colloidal solution includes: stirring at a third stirring speed for a third preset time, the third stirring speed ranging from 500rpm to 700rpm, and the third preset time ranging from 3min to 8min. For example, the third stirring speed can be 500rpm, 550rpm, 600rpm, 650rpm, 700rpm, etc., and the third preset time can be 3min, 4min, 5min, 6min, 7min, 8min, etc. By making the third stirring speed not less than 500rpm, lithium ions can be fully diffused in the colloidal solution, so that the lithium ions can be evenly dispersed in the transition metal; by making the third stirring speed not higher than 700rpm, performance can be saved while ensuring that the lithium ions can be fully dispersed.

[0057] According to some embodiments of the present invention, preparing a metal salt solution containing transition metal ions includes: weighing a soluble salt of a first transition metal, a soluble salt of a second transition metal, and a soluble salt of a third transition metal according to a stoichiometric ratio of the transition metal ions, and dissolving the mixture in water to form a metal salt solution. By preparing a soluble salt solution of multiple transition metals, the multiple transition metals can be fully and uniformly mixed.

[0058] According to some embodiments of the present invention, the soluble salt of the first transition metal includes at least one of nickel sulfate, nickel acetate, nickel nitrate, and nickel chloride; the soluble salt of the second transition metal includes at least one of cobalt sulfate, cobalt acetate, cobalt nitrate, and cobalt chloride; and the soluble salt of the third transition metal includes at least one of manganese sulfate, manganese acetate, manganese nitrate, and manganese chloride. By making the salts of the first, second, and third transition metals all soluble salts, the first, second, and third transition metals can be more easily dispersed and mixed in water.

[0059] Optionally, the soluble salt of the first transition metal is nickel nitrate, the soluble salt of the second transition metal is cobalt nitrate, and the soluble salt of the third transition metal is manganese nitrate.

[0060] According to some embodiments of the present invention, the concentration of the metal salt solution ranges from 1 mol / L to 2 mol / L. For example, the concentration of the metal salt solution can be 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, etc. By ensuring that the concentration of the metal salt solution is not less than 1 mol / L, sufficient metal salt ions can be ensured in the solution, and the drying and sintering time can be reduced; by ensuring that the concentration of the metal salt solution is not greater than 2 mol / L, the crystallization rate can be prevented from being too fast due to excessive concentration of metal salt ions, which makes it difficult to control.

[0061] According to some embodiments of the present invention, drying the gel-like material includes drying at a set drying temperature in the range of 70°C to 90°C. For example, the drying temperature may be 70°C, 75°C, 80°C, 85°C, 90°C, etc. The drying process can remove moisture from the gel-like material and reduce the time and conditions required for calcination. By setting the drying temperature between 70°C and 90°C, the moisture in the gel-like material can be fully evaporated.

[0062] Optionally, the equipment used for drying is a blast drying oven. By using the blast drying oven to dry the gel-like material, moisture in the material can be removed more efficiently and quickly.

[0063] According to some embodiments of the present invention, calcining the precursor includes: sintering the precursor at a first calcination temperature for a first calcination time in an oxygen atmosphere, then raising the temperature to a second calcination temperature, and sintering the precursor at the second calcination temperature for a second calcination time, wherein the second calcination time is longer than the first calcination time. By making the second calcination time longer than the first calcination time, the precursor can be calcined more fully.

[0064] According to some embodiments of the present invention, the first calcination temperature ranges from 400° C. to 500° C., and the second calcination temperature ranges from 800° C. to 900° C. By pre-calcining the precursor and then calcining it at a high temperature, the precursor can be fully calcined, allowing the precursor to be converted from a gel form to a solid state for preparation of a positive electrode material.

[0065] According to some embodiments of the present invention, the first calcination time ranges from 4 hours to 6 hours, and the second calcination time ranges from 10 hours to 14 hours. By setting the second calcination time to be no less than 10 hours, the precursor can be fully calcined; by setting the second calcination time to no more than 14 hours, time waste can be avoided while ensuring the precursor is fully calcined, thereby improving production efficiency.

[0066] According to some embodiments of the present invention, preparing a lithium salt solution includes: dissolving a lithium salt in water to form a lithium salt solution; wherein the lithium salt includes at least one of lithium hydroxide, lithium carbonate, lithium chloride, lithium nitrate, lithium acetate, and lithium oxalate. For example, the lithium salt includes lithium hydroxide. In another example, the lithium salt includes lithium hydroxide and lithium carbonate.

[0067] According to some embodiments of the present invention, the thickener includes at least one of carboxymethyl cellulose, alginic acid, konjac glucomannan, xanthan gum, carrageenan, locust bean gum, and guar gum. For example, the thickener includes konjac glucomannan; for another example, the thickener includes carboxymethyl cellulose; for another example, the thickener includes carboxymethyl cellulose and alginic acid.

[0068] According to some embodiments of the present invention, the first transition metal ion is a nickel ion, the second transition metal ion is a cobalt ion, and the third transition metal ion is a manganese ion or an aluminum ion. When the first transition metal ion is a nickel ion, by controlling the particle growth rate, the resulting positive electrode material can have a good crystalline structure, a low lithium-nickel mixing rate, reduced microcracks, and improved battery cycle performance.

[0069] For example, when the first transition metal ion is nickel ion, the second transition metal ion is cobalt ion, and the third transition metal ion is aluminum ion, the second calcination temperature is greater than 850° C. When the third transition metal ion is aluminum ion, a higher calcination temperature is required to fully calcine the precursor.

[0070] The positive electrode material according to the embodiment of the second aspect of the present invention is characterized in that the positive electrode material is prepared by the preparation method according to the embodiment of the first aspect of the present invention, the positive electrode material has a single crystal structure, and the chemical formula of the positive electrode material is LiNi x Co y Mn z O2, where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1. For example, the chemical formula of the positive electrode material may be LiNi 0.8 Co 0.1 Mn 0.1 O2

[0071] The positive electrode material according to the embodiment of the present invention is prepared by using the preparation method according to the embodiment of the first aspect of the present invention. A thickener is added during the production to prepare a first colloidal solution containing various transition metal ions, and then a lithium salt solution is poured into the colloidal solution to form a gel-like material, so that the lithium-nickel mixing rate of the positive electrode material is low, microcracks can be reduced, and the positive electrode material produced has better cycle performance.

[0072] The battery according to the embodiment of the third aspect of the present invention is characterized in that it includes: a battery case and a pole group. The pole group is arranged in the battery case, and the pole group includes stacked positive electrode plates and negative electrode plates. The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer coated on the positive electrode current collector, and the positive electrode active material layer includes the positive electrode material according to the embodiment of the second aspect of the present invention.

[0073] The battery according to the embodiment of the present invention includes the positive electrode material according to the embodiment of the second aspect of the present invention. The crystal phase structure of the positive electrode material is good, microcracks can be reduced, and the cycle performance of the battery is better.

[0074] For example, the battery is a lithium battery. By including the positive electrode material according to the embodiment of the second aspect of the present invention, the crystal phase structure of the positive electrode material is good, the lithium-nickel mixing rate is low, microcracks can be reduced, and the cycle performance of the battery is better.

[0075] The electrical device according to the embodiment of the fourth aspect of the present invention is characterized in that it includes: the battery according to the embodiment of the third aspect of the present invention.

[0076] The electrical device according to the embodiment of the present invention includes the battery according to the embodiment of the third aspect of the present invention. The cycle performance of the battery is better and the lifespan is longer.

[0077] The positive electrode material of the embodiment of the present invention will be further described below in conjunction with some examples and comparative examples.

[0078] I. Preparation of materials.

[0079] (1). Preparation of nickel-cobalt-manganese positive electrode materials for each example and comparative example.

[0080] Prepare nickel-cobalt-manganese positive electrode materials. The nickel-cobalt-manganese positive electrode materials of the following embodiments are prepared by the preparation method according to the embodiment of the first aspect of the present invention, and the nickel-cobalt-manganese positive electrode materials of the comparative examples are prepared by the coprecipitation method in the related art.

[0081] Example 1: Dissolve carboxymethyl cellulose in 400 mL of deionized water at a ratio of 0.1 wt%, stir at 200 rpm for 5 min, then gradually increase the speed to 600 rpm and stir for 1 h to form a colorless colloidal solution. Weigh 8.72 g of Ni(NO3)2·6H2O, 1.09 g of Co(NO3)2·6H2O and 1.88 g of Mn(NO3)2·4H2O and add them to 30 mL of deionized water, stir at 500 rpm, and after all are dissolved, add them to the colorless colloidal solution and stir at 600 rpm for 5 min to form a uniform colloidal solution. According to TM:Li + LiOH·H2O was weighed and dissolved in 30 mL of deionized water in a ratio of 1:1.05. The solution was gradually poured into the colloidal solution. After precipitation appeared, the solution was transferred to an 80°C forced air drying oven for drying. The precursor was calcined in oxygen at 450°C for 5 h, then at 850°C for 12 h, and ground to obtain the nickel-cobalt-manganese cathode material.

[0082] Example 2: Alginic acid was dissolved in 400 mL of deionized water at a ratio of 0.1 wt%, stirred at 200 rpm for 5 min, then gradually increased to 600 rpm and stirred for 1 h to form a colorless colloidal solution. 8.72 g of Ni(NO3)2·6H2O, 1.09 g of Co(NO3)2·6H2O and 1.88 g of Mn(NO3)2·4H2O were weighed and added to 30 mL of deionized water, stirred at 500 rpm. After all the solution was dissolved, the mixture was added to the colorless colloidal solution and stirred at 600 rpm for 5 min to form a uniform colloidal solution. According to TM:Li + LiOH·H2O was weighed and dissolved in 30 mL of deionized water in a ratio of 1:1.05. The solution was gradually poured into the colloidal solution. After precipitation appeared, the solution was transferred to an 80°C forced air drying oven for drying. The precursor was calcined in oxygen at 450°C for 5 h, then at 850°C for 12 h, and ground to obtain the nickel-cobalt-manganese cathode material.

[0083] Example 3: Konjac glucomannan was dissolved in 400 mL of deionized water at a ratio of 0.1 wt%, stirred at 200 rpm for 5 min, then gradually increased to 600 rpm and stirred for 1 h to form a colorless colloidal solution. 8.72 g of Ni(NO3)2·6H2O, 1.09 g of Co(NO3)2·6H2O and 1.88 g of Mn(NO3)2·4H2O were weighed and added to 30 mL of deionized water, stirred at 500 rpm. After all the solution was dissolved, the mixture was added to the colorless colloidal solution and stirred at 600 rpm for 5 min to form a uniform colloidal solution. According to TM:Li+ LiOH·H2O was weighed and dissolved in 30 mL of deionized water in a ratio of 1:1.05. The solution was gradually poured into the colloidal solution. After precipitation appeared, the solution was transferred to an 80°C forced air drying oven for drying. The precursor was calcined in oxygen at 450°C for 5 h, then at 850°C for 12 h, and ground to obtain the nickel-cobalt-manganese cathode material.

[0084] Comparative Example 1: Selecting polycrystalline precursor material Ni 0.8 Mn 0.1 Co 0.1 (OH)2 was used as a nickel-cobalt-manganese ternary precursor. 5g of a commercial polycrystalline precursor and 2.386g of LiOH·H2O were weighed and ground in a ratio of TM:Li+ = 1:1.05. The mixture was calcined in oxygen at 450°C for 5h and then at 850°C for 12h to obtain the nickel-cobalt-manganese cathode material.

[0085] (2) Preparation of positive electrode sheets of various embodiments and comparative examples.

[0086] The nickel-cobalt-manganese positive electrode material, conductive carbon black (Super-P) and binder polyvinylidene fluoride (PVDF) containing N-methyl-2-pyrrolidone (NMP) prepared above were mixed in a mass ratio of 8:1:1 and stirred for 0.5 h using a magnetic stirrer to obtain a positive electrode slurry. The positive electrode slurry was evenly coated on one side of a clean aluminum foil surface, dried, and cut into pieces to obtain a positive electrode sheet for testing.

[0087] (3) Preparation of button-type half-cells of various embodiments and comparative examples.

[0088] In a glove box with a moisture and oxygen content below 10 ppm and filled with argon, the obtained positive electrode sheet was used, a lithium sheet was used as the negative electrode, an electrolyte of 1 mol / L LiPF6 (solvent is EC:DMC:EMC=1:1:1) was added, and a polypropylene separator with a thickness of 20 μm was used to assemble a CR2032 button battery.

[0089] 2. Related tests

[0090] (1) XRD test was performed on the positive electrode materials prepared in Example 1, Example 2 and Example 3.

[0091] Reference Figure 1 , Figure 1 The XRD patterns obtained by XRD testing of the positive electrode materials prepared in Example 1, Example 2 and Example 3. Figure 1In the figure, (a) is the full XRD spectrum of Example 1, Example 2 and Example 3, (b) is the (006) / (102) diffraction peak regional spectrum of Example 1, Example 2 and Example 3, (c) is the (018) / (110) diffraction peak regional spectrum of Example 1, Example 2 and Example 3, (d), (e) and (f) are the XRD refined spectra of Example 1, Example 2 and Example 3, respectively.

[0092] from Figure 1 It can be seen from (a) that the characteristic peaks of the positive electrode materials of Examples 1, 2 and 3 are all α-NaFeO2 structures of R-3m space group. Figure 1 (b) and Figure 1 In (c), it can be seen that the (006) / (102) and (018) / (110) peaks of the positive electrode materials of Examples 1, 2, and 3 are clearly split, indicating that a good layered structure has been formed. The c / a ratios of the positive electrode materials of Examples 1, 2, and 3 are all greater than 4.92, indicating that the positive electrode materials of Examples 1, 2, and 3 have all formed an excellent hexagonal structure.

[0093] The XRD patterns of the cathode materials of Example 1, Example 2 and Example 3 were refined using Fullprof software, and the unit cell parameters of the cathode materials of Example 1, Example 2 and Example 3 were obtained as shown in Table 1.

[0094] Table 1

[0095]

[0096] It can be seen from Table 1 that the ratio of I(003) / I(104) of Example 1 and Example 3 is slightly less than 1.2, so their Li+ / Ni 2+ The mixing rate is higher, 5.6% and 6.6%. The ratio of I(003) / I(104) in Example 2 is greater than 1.2, and its Li+ / Ni 2+ The degree of mixing is relatively low, only 3.6%.

[0097] (2) Electron microscope scanning was performed on the positive electrode materials prepared in Example 1, Example 2 and Example 3 to obtain SEM images of the positive electrode materials prepared in Example 1, Example 2 and Example 3.

[0098] Reference Figure 2 , Figure 2 is the SEM image of the positive electrode materials prepared in Example 1, Example 2 and Example 3, wherein Figure 2 In the embodiment 1, (a) and (d) are embodiment 1, (b) and (e) are embodiment 2, and (c) and (f) are embodiment 3.

[0099] Reference Figure 2 , Figure 2 The positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 SEM image of O2. Figure 2 It can be seen that the primary particles of Examples 1 and 3 have a particle size of approximately 1 to 3 μm, are mostly irregular in shape, and a small amount of material has obvious angular morphology. The primary particles of Example 2 have a particle size of approximately 0.5 to 2 μm, which is more uniform than the other two materials. Although they are also irregular in shape, their morphology is more rounded.

[0100] (3) The XPS spectrum of the positive electrode material of Example 2 obtained by X-ray photoelectron spectroscopy (XPS) testing.

[0101] Reference Figure 3 , Figure 3 The XPS spectrum of the positive electrode material of Example 2 is shown.

[0102] from Figure 3 It can be seen that the binding energy peaks of Ni 2p3 / 2 and Ni 2p1 / 2 are 855.17eV and 872.78eV respectively, and the two satellite peaks are 861.08eV and 879.38eV respectively. The higher the binding energy of the Ni 2p3 / 2 peak, the higher the average valence of the Ni ion. The binding energy peaks of Co 2p3 / 2 and Co 2p1 / 2 are 780.88eV and 795.58eV respectively. The binding energy peaks of Mn 2p3 / 2 and Mn 2p1 / 2 are 642.38eV and 654.08eV respectively. The XPS data of the material were further separated and fitted using Avantage software. The main peak at 855.38eV belongs to Ni 2+ , the main peak at 856.68 eV belongs to Ni 3+ , where Ni 2+ The ratio is 65.15%, Ni 3+ The ratio is 34.85%.

[0103] (4) The cathode material of Example 2 was characterized using TEM, selected area electron diffraction (SEAD) and EDS mapping.

[0104] Reference Figure 4 , Figure 4 The characterization results of Example 2 using TEM, selected area electron diffraction (SEAD) and EDS Mapping are shown, wherein Figure 4 (a) is the TEM image, (b) is the TEM magnified image, (c) is the FFT image, (d) and (e) are the IFFT images, (f) is the Mapping image, and (g) is the selected area electron diffraction image.

[0105] from Figure 4 (a) and Figure 4 In (b), it can be seen that the lattice spacing of the sample is 0.4774nm, corresponding to the (003) crystal plane. Figure 4 In the TEM magnification of (b), the darker layer is the lithium layer, the brighter layer is the transition metal layer, and in the yellow box, some gray spots can be seen in the darker lithium layer, indicating that there are transition metal atoms in the lithium layer and lithium-nickel mixed arrangement in the material. EDS spectrum of the material Figure 4 (f) shows that Ni, Co, Mn and O elements are uniformly distributed throughout the primary particles. Figure 4 The diffraction pattern in the SAED image of (g) is a hexagonal lattice, indicating that the material is a single crystal material. After calibration, the structure of the material is a hexagonal layered structure.

[0106] (5) After the button-type batteries in Example 2 and Comparative Example 1 were cycled for 200 cycles, cross-sectional SEM images were obtained.

[0107] Reference Figure 5 , Figure 5 Figure 5 shows cross-sectional SEM images of the button cells of Example 2 and Comparative Example 1 after 200 cycles. Figure 5 shows that the button cell of Example 2 maintains its initial structure after 200 cycles, with no obvious intragranular microcracks, while the button cell of Comparative Example 1 develops significant microcracks along the grain boundaries in the center of the secondary particles.

[0108] (6) The button batteries in Example 1, Example 2, Example 3 and Comparative Example 1 were subjected to electrochemical performance tests. The electrochemical performance tests included:

[0109] The cycle performance test was carried out by charging the battery to 4.5V at a constant current of 1.0C and then discharging the battery to 2.5V at a constant current for 200 cycles at room temperature to obtain the room temperature cycle performance data.

[0110] Reference Figure 6 , Figure 6 The electrochemical performance graphs obtained by performing electrochemical performance tests on the button batteries in Example 1, Example 2, Example 3 and Comparative Example 1 are shown, and the cycle performance test results of the button batteries in Example 1, Example 2, Example 3 and Comparative Example 1 are shown.

[0111] In order to highlight the cycling performance differences among Example 1, Example 2, Example 3 and Comparative Example 1, the voltage window was increased from the conventional 3-4.2 V to 2.5-4.5 V to accelerate the attenuation of the material during the cycling process.

[0112] from Figure 6It can be seen that the capacities of the four materials (i.e., the positive electrode materials involved in Example 1, Example 2, Example 3 and Comparative Example 1) at a rate of 1C are 159.39 mAh / g, 176.98 mAh / g, 159.94 mAh / g and 183.48 mAh / g, respectively. The discharge specific capacity of Comparative Example 1 is still the highest, and the discharge specific capacity of Example 2 is higher than that of Example 1 and Example 3.

[0113] After 200 cycles, the discharge specific capacities of the four materials were 98.18 mAh / g, 101.09 mAh / g, 97.94 mAh / g and 31.87 mAh / g, respectively, and the capacity retention rates were 61.60%, 57.12%, 61.24% and 17.37%, respectively.

[0114] The cycle retention rates of Example 1, Example 2, and Example 3 are all much higher than those of Comparative Example 1.

[0115] In the description of the present invention, "first feature" or "second feature" may include one or more of the features.

[0116] In the description of the present invention, "plurality" means two or more.

[0117] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0118] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a positive electrode material, characterized in that: include: preparing a first colloidal solution, the first colloidal solution comprising water, a thickener, and transition metal ions, the transition metal ions comprising a first transition metal ion, a second transition metal ion, and a third transition metal ion, the first transition metal ion being a nickel ion, the second transition metal ion being a cobalt ion, and the third transition metal ion being a manganese ion; preparing a lithium salt solution; pouring the lithium salt solution into the first colloidal solution to form a gel-like material; drying the gel-like material to obtain a precursor; The precursor is calcined to obtain the positive electrode material.

2. The method for preparing the positive electrode material according to claim 1, wherein: The first colloidal solution is prepared, comprising: mixing the thickener with water and stirring to form a second colloidal solution; preparing a metal salt solution containing the transition metal ion; The metal salt solution and the second colloidal solution are mixed and stirred to form the first colloidal solution.

3. The method for preparing the positive electrode material according to claim 2, wherein: The thickener accounts for 0.05 wt % to 0.15 wt % in the second colloidal solution.

4. The method for preparing the positive electrode material according to claim 2, wherein: The stirring to form a second colloidal solution comprises: After stirring at a first stirring speed for a first preset time, the stirring speed is gradually increased to a second stirring speed, and stirring is carried out at the second stirring speed for a second preset time, wherein the second preset time is longer than the first preset time.

5. The method for preparing the positive electrode material according to claim 4, wherein: The first stirring speed ranges from 180 rpm to 220 rpm, and the second stirring speed ranges from 500 rpm to 700 rpm; and / or the first stirring time ranges from 3 min to 8 min, and the second stirring time ranges from 45 min to 75 min.

6. The method for preparing the positive electrode material according to claim 2, wherein: The stirring to form the first colloidal solution comprises: The mixture is stirred at a third stirring speed for a third preset time, wherein the third stirring speed ranges from 500 rpm to 700 rpm, and the third preset time ranges from 3 min to 8 min.

7. The method for preparing the positive electrode material according to claim 2, wherein: The method comprises preparing a metal salt solution containing the transition metal ion, comprising: The transition metal ions are weighed according to a stoichiometric ratio, and the soluble salt of the first transition metal, the soluble salt of the second transition metal, and the soluble salt of the first transition metal are dissolved in water to form the metal salt solution.

8. The method for preparing the positive electrode material according to claim 7, wherein: The soluble salt of the first transition metal includes at least one of nickel sulfate, nickel acetate, nickel nitrate and nickel chloride, the soluble salt of the second transition metal includes at least one of cobalt sulfate, cobalt acetate, cobalt nitrate and cobalt chloride, and the soluble salt of the third transition metal includes at least one of manganese sulfate, manganese acetate, manganese nitrate and manganese chloride.

9. The method for preparing the positive electrode material according to claim 7, wherein: The concentration of the metal salt solution is in the range of 1 mol / L to 2 mol / L.

10. The method for preparing the positive electrode material according to claim 1, wherein: The gel-like material is dried, comprising: The drying is performed at a set drying temperature, wherein the set drying temperature ranges from 70°C to 90°C.

11. The method for preparing a positive electrode material according to claim 1, wherein: calcining the precursor, comprising: The first calcination time is sintered at a first calcination temperature in an oxygen atmosphere, and then the temperature is increased to a second calcination temperature, and the second calcination time is sintered at the second calcination temperature, wherein the second calcination time is longer than the first calcination time.

12. The method for preparing the positive electrode material according to claim 11, wherein: The first calcination temperature ranges from 400° C. to 500° C., and the second calcination temperature ranges from 800° C. to 900° C.; and / or the first calcination time ranges from 4 h to 6 h, and the second calcination time ranges from 10 h to 14 h.

13. The method for preparing a positive electrode material according to claim 1, wherein: The preparation of the lithium salt solution comprises: dissolving a lithium salt in water to form the lithium salt solution; The lithium salt includes at least one of lithium hydroxide, lithium carbonate, lithium chloride, lithium nitrate, lithium acetate and lithium oxalate.

14. The method for preparing a positive electrode material according to claim 1, wherein: The thickener comprises at least one of carboxymethyl cellulose, alginic acid, konjac glucomannan, xanthan gum, carrageenan, locust bean gum and guar gum.

15. A positive electrode material, characterized in that The positive electrode material is prepared by the preparation method according to any one of claims 1 to 14, and the positive electrode material is a single crystal structure and the chemical formula of the positive electrode material is LiNi x Co y Mn z O2, where 0 <x<1, 0<y<1,0<z<1,x+y+z=1。 16. A battery, characterized in that: include: Battery housing; An electrode group is arranged in the battery shell and includes a stacked positive electrode sheet and a negative electrode sheet, the positive electrode sheet includes a positive electrode collector and a positive electrode active material layer coated on the positive electrode collector, and the positive electrode active material layer includes the positive electrode material according to claim 15.

17. An electrical device, characterized in that: include: The battery according to claim 16.

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