A layered large single crystal positive electrode material for lithium-ion batteries and its preparation method and application

Abstract

The present invention belongs to the technical field of lithium-ion batteries, and relates to positive electrode materials for lithium-ion batteries, and specifically relates to a layered large single crystal positive electrode material for lithium-ion batteries, as well as a preparation method and application thereof. After a ternary precursor is uniformly mixed with a lithium source and a nano-sized aluminum source, the mixture is sintered and crushed to obtain a single crystal substrate; after a single crystal substrate is uniformly mixed with a nano-sized cerium source, the mixture is sintered and crushed to obtain a coated and modified substrate; after a ternary precursor is uniformly mixed with a lithium source and a nano-sized aluminum source, the mixture is sintered and crushed to obtain a single crystal coating material; after a coated and modified substrate is uniformly mixed with a single crystal coating material, the mixture is sintered and crushed to obtain the product. The present invention uses a coating and crystal plane adjustment method to re-fusion grow on the original 3-5μm single crystal substrate to achieve the purpose of promoting grain growth, so as to synthesize 6-10μm large-particle single crystals, thereby improving the energy density and safety of lithium-ion batteries, and at the same time solving the problem of severe mixed arrangement and easy cracking of large single crystals prepared at high temperature with lithium-nickel.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries and relates to positive electrode materials for lithium-ion batteries, and in particular to a layered large single crystal positive electrode material for lithium-ion batteries and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Range anxiety is an industry challenge that new energy vehicles must face. There are currently two main solutions: one is to improve mass energy density, and the other is to improve volume energy density. Mass energy density is mainly achieved by using higher-density cathode materials and lightweight battery pack design. Volume energy density is mainly achieved through large-scale modularization, but is to some extent limited by the volume energy density of individual battery cells.

[0004] Patent CN106910882A and Patent CN107311242A disclose a method for preparing large single crystal layered positive electrode materials for lithium-ion batteries based on the step-by-step addition of lithium to the precursor. The characteristics of the method are: (1) the spinel phase formed by lithium deficiency is used to facilitate the fusion and growth of primary grains under high-temperature calcination, thereby obtaining lithium-deficient micron composite phases or pure phase primary grains with larger sizes; (2) lithium is then added to the grains prepared above, and large single crystal layered positive electrode materials can be obtained after calcination at high temperature. The inventors found that the deficiency of the method is that the lack of lithium in the first preparation process will inevitably cause lattice distortion and more lithium sites in the lithium layer will be replaced by Ni. 2+ In the second step, lithium is added because the substrate particles have grown and the lithium ion embedding path is long. 2+ The presence of certain steric hindrance and the re-collapse of the substrate crystal structure under high temperature conditions will lead to a decline in the material's specific capacity, cycle performance and other performance.

[0005] According to the inventors' research, the aforementioned patents all achieve large single crystals through high-temperature calcination and a two-stage lithium replenishment strategy. While this achieves large single crystals, the two-stage lithium replenishment results in a lithium content significantly below the stoichiometric value, which in turn severely impacts the material's specific capacity and cycling performance. Therefore, how to prepare large single crystals while minimizing electrical performance loss, particularly due to lithium deficiency and lithium-nickel intermixing, remains a pressing technical challenge in this field. Summary of the Invention

[0006] In order to improve the energy density and safety of lithium-ion batteries and solve the preparation problems of large single crystals prepared at high temperature, such as serious lithium-nickel mixing and easy cracking, the present invention provides a layered large single crystal positive electrode material for lithium-ion batteries and a preparation method and application. The present invention uses coating and crystal plane adjustment methods to re-fusion and grow on the original 3-5μm single crystal substrate to achieve the purpose of promoting grain growth, and then synthesize 6-10μm large-grain single crystals.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] In one aspect, a method for preparing a layered large single crystal positive electrode material for a lithium-ion battery comprises the following steps:

[0009] After the ternary precursor is uniformly mixed with the lithium source and the nano-sized aluminum source, the mixture is sintered once in air or oxygen atmosphere, and crushed to obtain a single crystal substrate with a particle size of 3 to 5 μm; the amount of the nano-sized aluminum source added is 500 to 1500 ppm based on the aluminum element;

[0010] The single crystal substrate and the nano-sized cerium source are mixed evenly, and then secondary sintered in air or oxygen atmosphere, and crushed to obtain a coated and modified substrate; the amount of the nano-sized cerium source added is 500 to 2000 ppm;

[0011] After the ternary precursor is evenly mixed with the lithium source and the nano-sized aluminum source, the mixture is sintered three times in air or oxygen atmosphere, and the single crystal coating material with a particle size of less than 2 μm is obtained after crushing; the addition amount of the nano-sized aluminum source is 500 to 1500 ppm;

[0012] The coated and modified substrate and the single crystal coating material are evenly mixed in a mass ratio of 1:1 to 3, sintered four times in air or oxygen atmosphere, and crushed to obtain large single crystals with a particle size of about 6 to 10 μm, namely, layered large single crystal positive electrode materials.

[0013] The present invention first uses cerium to adjust the crystal plane to reduce the potential energy of crystal plane growth and fusion. The present invention uses a nano-cerium source, which can be better mixed with the ternary precursor, which is beneficial for incorporating into the crystal to achieve crystal plane adjustment, making it easier for crystal particles to fuse and grow, and can increase the tap density to increase the electrode compaction density, thereby improving the volume energy density of the lithium-ion battery, while solving the preparation problem of severe mixing and cracking of large single crystal lithium nickel prepared at high temperature.

[0014] The present invention adopts nano-aluminum source to modify the material, thereby ensuring the cyclic stability of the material.

[0015] On the other hand, a layered large single crystal positive electrode material for lithium-ion batteries is obtained by the above preparation method.

[0016] The third aspect is the application of a layered large single crystal positive electrode material for lithium-ion batteries in lithium-ion batteries.

[0017] In a fourth aspect, a lithium-ion battery comprises a positive electrode, a negative electrode, an electrolyte and a separator, wherein the positive electrode material used in the positive electrode is the above-mentioned layered large single crystal positive electrode material for lithium-ion batteries.

[0018] The beneficial effects of the present invention are:

[0019] The present invention prepares a single crystal coating material with a particle size of less than 2μm for coating. Cerium is then used to adjust the crystal planes, reducing the potential energy of crystal growth and fusion. This allows the original 3-5μm single crystal substrate and the single crystal coating material to fuse and re-grow, promoting the growth of the grains into large single crystals of 6-10μm particles. Experiments have shown that the positive electrode material with large single crystal particles of 6-10μm prepared by the present invention has a higher tap density and electrode compaction density, thereby improving the volumetric energy density of lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0021] Figure 1 This is an SEM image of the large single crystal positive electrode material prepared in Example 1 of the present invention;

[0022] Figure 2 This is an SEM image of the large single crystal positive electrode material prepared in Comparative Example 1 of the present invention;

[0023] Figure 3 This is an SEM image of the large single crystal positive electrode material prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0025] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0026] In view of the fact that lithium-ion batteries using large single crystal positive electrode materials have problems such as low energy density, the present invention proposes a layered large single crystal positive electrode material for lithium-ion batteries, a preparation method and an application thereof.

[0027] A typical embodiment of the present invention provides a method for preparing a layered large single crystal positive electrode material for a lithium ion battery, comprising the following steps:

[0028] After the ternary precursor is evenly mixed with the lithium source and the nano-sized aluminum source, the mixture is sintered once in air or oxygen atmosphere, and crushed to obtain a single crystal substrate with a particle size of 3 to 5 μm; the amount of the nano-sized aluminum source added is 500 to 1500 ppm;

[0029] The single crystal substrate and the nano-sized cerium source are mixed evenly, and then secondary sintered in air or oxygen atmosphere, and crushed to obtain a coated and modified substrate; the amount of the nano-sized cerium source added is 500 to 2000 ppm;

[0030] After the ternary precursor is evenly mixed with the lithium source and the nano-sized aluminum source, the mixture is sintered three times in air or oxygen atmosphere, and the single crystal coating material with a particle size of less than 2 μm is obtained after crushing; the addition amount of the nano-sized aluminum source is 500 to 1500 ppm;

[0031] The coated and modified substrate and the single crystal coating material are evenly mixed in a mass ratio of 1:1 to 3, sintered four times in air or oxygen atmosphere, and crushed to obtain large single crystals with a particle size of about 6 to 10 μm, namely, layered large single crystal positive electrode materials.

[0032] The lithium source described in the present invention is a substance containing lithium, such as lithium salt, lithium hydroxide, lithium oxide, etc.

[0033] The aluminum source of the present invention is a substance containing aluminum, such as aluminum salt, aluminum hydroxide, aluminum oxide, etc. The nano-sized aluminum source is preferably nano-aluminum oxide.

[0034] The aluminum source of the present invention is a substance containing cerium, such as cerium salt, cerium hydroxide, cerium oxide, etc. The nanosized cerium source is preferably nano cerium oxide.

[0035] The particle size described in the present invention is D50.

[0036] In some embodiments, the D50 of the ternary precursor for preparing the single crystal substrate is 3-5 μm.

[0037] In some embodiments, when preparing a single crystal substrate, the molar ratio of lithium to the metal element in the ternary precursor (Li / Me) is 1.03 to 1.07: 1. This not only avoids lithium deficiency but also avoids waste of lithium resources.

[0038] In some embodiments, the D50 of the ternary precursor for preparing the single crystal coating material is 0.5-2.5 μm.

[0039] In some embodiments, when preparing a single crystal coating material, the molar ratio of lithium element to the metal element in the ternary precursor (Li / Me) is 1.03 to 1.07:1.

[0040] Another embodiment of the present invention provides a layered large single crystal positive electrode material for lithium-ion batteries, which is obtained by the above-mentioned preparation method.

[0041] A third embodiment of the present invention provides a use of the above-mentioned layered large single crystal positive electrode material for lithium-ion batteries in lithium-ion batteries.

[0042] Specifically, the layered large single crystal cathode material for a lithium-ion battery is mixed with a conductive agent, a binder, and a solvent to form a slurry. The slurry is then applied to a current collector surface and dried to obtain a positive electrode. The positive electrode, negative electrode, electrolyte, and separator are then assembled into a lithium-ion battery. The negative electrode, electrolyte, and separator can all be made of the same materials as conventional lithium-ion batteries.

[0043] A fourth embodiment of the present invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode, an electrolyte and a separator, wherein the positive electrode material used in the positive electrode is the above-mentioned layered large single crystal positive electrode material for lithium-ion batteries.

[0044] Specifically, the positive electrode includes a current collector, an active layer is arranged on the surface of the current collector, and the active layer contains the layered large single crystal positive electrode material for the lithium ion battery, a conductive agent, and a binder.

[0045] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0046] Example 1

[0047] 1. Weigh 3000g of NCM702010 ternary precursor with a D50 of 3-5μm. Add sufficient lithium hydroxide monohydrate to achieve a molar ratio of lithium to nickel, cobalt, and manganese of Li / Me = 1.05. Also, add sufficient nano-alumina to achieve a designed concentration of 1000ppm. Pour the weighed materials into a mixer and mix thoroughly. Sinter the mixed materials at 880°C in an oxygen atmosphere for 11 hours. The sintered materials are then pulverized to produce a single-crystal substrate with a particle size of 3-5μm.

[0048] 2. Weigh 2000g of the single crystal substrate and a sufficient amount of nano-cerium oxide to achieve a coating concentration of 500ppm. Pour the weighed substrate and coating agent into a mixing apparatus and mix thoroughly. Sinter the mixture at 600°C in an oxygen atmosphere for 6 hours. Then, crush and sieve the mixture to obtain the coated substrate.

[0049] 3. Weigh 3000g of NCM702010 ternary precursor with a D50 of 0.5-2.5μm. Add sufficient lithium hydroxide monohydrate to achieve a lithium to nickel, cobalt, and manganese molar ratio of Li / Me = 1.07. Also, add sufficient nano-alumina to achieve a designed dosage of 1500ppm. Pour the weighed materials into a mixer and mix thoroughly. Sinter the mixed materials at 875°C in an oxygen atmosphere for 11 hours. The sintered materials are crushed to obtain single crystals with a particle size of <2μm. These single crystals are used as the coating material.

[0050] 4. Weigh 1500g of the coated substrate and mix it evenly with the coated substrate and coating material in a mass ratio of 1:2. Then, sinter the mixed materials at high temperature in an oxygen atmosphere. The sintered materials are crushed and sieved to obtain large single crystals with a particle size of about 6 to 10μm. Figure 1 shown.

[0051] Example 2

[0052] 1. Weigh 3000g of NCM701515 ternary precursor with a D50 of 3-5μm. Add sufficient lithium hydroxide monohydrate to achieve a molar ratio of lithium to nickel, cobalt, and manganese of Li / Me = 1.03. Also, add sufficient nano-alumina to achieve a designed concentration of 500ppm. Pour the weighed materials into a mixer and mix thoroughly. Sinter the mixed materials at 880°C in an oxygen atmosphere for 11 hours. The sintered materials are then pulverized to produce a single-crystal substrate with a particle size of 3-5μm.

[0053] 2. Weigh 2000g of the above-mentioned single crystal substrate and a sufficient amount of nano-cerium oxide to achieve a coating concentration of 1000ppm. Pour the weighed substrate and coating agent into a mixing device and mix thoroughly. Sinter the mixture at 600°C in an oxygen atmosphere for 6 hours. Then, crush and sieve the mixture to obtain the coated substrate.

[0054] 3. Weigh 3000g of NCM751015 ternary precursor with a D50 of 0.5-2.5μm. Add sufficient lithium hydroxide monohydrate to achieve a molar ratio of lithium to nickel, cobalt, and manganese of Li / Me = 1.05. Also, add sufficient nano-alumina to achieve a designed dosage of 1000ppm. Pour the weighed materials into a mixer and mix thoroughly. Sinter the mixed materials at 865°C in an oxygen atmosphere for 11 hours. The sintered materials are crushed to obtain single crystals with a particle size of <2μm. These single crystals are used as the coating material.

[0055] 4. Weigh 1500g of the coated substrate and mix it evenly with the coating material in a mass ratio of 1:3. Then, sinter the mixed material at high temperature in an oxygen atmosphere. The sintered material is crushed and sieved to obtain large single crystals with a particle size of about 6-10μm.

[0056] Example 3

[0057] 1. Weigh 3000g of NCM751015 ternary precursor with a D50 of 3-5μm. Add sufficient lithium hydroxide monohydrate to achieve a molar ratio of lithium to nickel, cobalt, and manganese of Li / Me = 1.03. Also, add sufficient nano-alumina to achieve a designed concentration of 500ppm. Pour the weighed materials into a mixer and mix thoroughly. Sinter the mixed materials at 870°C in an oxygen atmosphere for 11 hours. The sintered materials are then pulverized to produce a single-crystal substrate with a particle size of 3-5μm.

[0058] 2. Weigh 2000g of the above-mentioned single crystal substrate and a sufficient amount of nano-cerium oxide to achieve a coating concentration of 1000ppm. Pour the weighed substrate and coating agent into a mixing device and mix thoroughly. Sinter the mixture at 600°C in an oxygen atmosphere for 6 hours. Then, crush and sieve the mixture to obtain the coated substrate.

[0059] 3. Weigh 3000g of NCM751015 ternary precursor with a D50 of 0.5-2.5μm. Add sufficient lithium hydroxide monohydrate to achieve a lithium to nickel, cobalt, and manganese molar ratio of Li / Me = 1.05. Also, add sufficient nano-alumina to achieve a designed dosage of 1000ppm. Pour the weighed materials into a mixer and mix thoroughly. Sinter the mixed materials at 860°C in an oxygen atmosphere for 11 hours. The sintered materials are crushed to obtain single crystals with a particle size of <2μm. These single crystals are used as the coating material.

[0060] 4. Weigh 1500g of the coated substrate and mix it evenly with the coating material in a mass ratio of 1:3. Then, sinter the mixed material at high temperature in an oxygen atmosphere. The sintered material is crushed and sieved to obtain large single crystals with a particle size of about 6-10μm.

[0061] Comparative Example 1:

[0062] 1. Weigh 3000g of NCM702010 ternary precursor with a D50 of 3-5μm. Add sufficient lithium hydroxide monohydrate to achieve a lithium to nickel, cobalt, and manganese molar ratio of Li / Me = 0.8. Also, add sufficient nano-alumina to achieve a designed concentration of 1000ppm. Pour the weighed materials into a blender and mix thoroughly. Sinter the blended materials at 920°C in an oxygen atmosphere for 11 hours. Grind the sintered materials to obtain composite primary grains with a particle size of 3-5μm.

[0063] 2. Add lithium source to the primary crystals obtained in step 1 so that the molar ratio of lithium to transition metal elements in the mixture is Li / NiCoMn=1.05, and sinter the compound at 880°C for 11 hours in an oxygen atmosphere to transform the spinel phase into a layered phase, and finally form a pure phase 6-10 μm large single crystal layered positive electrode material, such as Figure 2 shown.

[0064] Comparative Example 2:

[0065] 1. Weigh 3000g of NCM702010 ternary precursor with a D50 of 3-5μm, weigh enough lithium hydroxide monohydrate according to the molar ratio of lithium to nickel, cobalt and manganese of Li / Me=1.05, and weigh enough nano-alumina according to the designed amount of 1000ppm. Pour the weighed materials into the mixer and mix them evenly. Then sinter the mixed materials at 880℃ in an oxygen atmosphere for 11h, and crush the sintered materials to obtain pure phase primary grains with a particle size of 2-3μm, such as Figure 3 shown.

[0066] The XRD refinement calculation results of Examples 1 to 3 and Comparative Examples 1 to 2 are shown in Table 1.

[0067] Table 1 XRD refinement calculation results

[0068] (003) (104) I(003) / I(104) Sample batch number Peak position Clearance Peak position Clearance Example 1 18.655 479.515 44.326 245.883 1.95 Example 2 18.658 487.162 44.329 248.864 1.96 Example 3 18.661 482.357 44.328 247.965 1.94 Comparative Example 1 18.668 407.712 44.335 271.856 1.50 Comparative Example 2 18.665 462.515 44.322 285.883 1.62

[0069] The industry generally uses the ratio of I(003) / I(104) to judge the degree of cation mixing in a material. As can be seen from the I(003) / I(104) ratios in Table 1, the I(003) / I(104) ratios of Examples 1, 2, and 3 are all above 1.9, while the I(003) / I(104) ratios of Comparative Examples 1 and 2 are significantly lower than those of the Examples, indicating that the degree of cation mixing in the Examples is lower than that in the Comparative Examples.

[0070] Preparation of button batteries: The positive electrode materials prepared in Examples 1 to 3 and Comparative Examples 1 to 2 are respectively assembled as button batteries, specifically as follows: the positive electrode material, conductive agent (acetylene black) and binder (PVDF) are weighed in a mass ratio of 90%:5%:5%, and the weighed positive electrode material and acetylene black are mixed and ground in an agate mortar. After grinding evenly, they are added to N-methylpyrrolidone (NMP) that has fully reacted with PVDF and continuously ground until the slurry becomes a viscous liquid with a certain fluidity. The ground slurry is evenly transferred to aluminum foil, and the sample is evenly coated with a coater with a thickness of 300 μm. It is then pre-baked in air at 60°C for 5 hours, then vacuumed and dried at 90°C for 12 hours to remove water and organic matter from the coated sample. The electrode sheet is cut out according to size for standby use to obtain the positive electrode sheet.

[0071] A lithium sheet was used as the negative electrode, the prepared electrode sheet as the positive electrode, and the electrolyte ratio was 1:1. Coin-shaped batteries were assembled and then charged and discharged using a BTV charge-discharge tester. The results show that at 25°C, the lithium-ion batteries assembled with the above-mentioned positive electrode sheet had an initial discharge capacity of 0.2C at an operating voltage of 3.0-4.4V, as shown in Table 2.

[0072] Table 2 Physical, chemical and electrical properties test results

[0073]

[0074] It can be seen from Table 2 that the size of the single crystal particles prepared in Examples 1, 2, and 3 is significantly increased, and D50 can reach about 7 μm, which is significantly higher than that in Comparative Example 2, resulting in the tap density of Examples 1, 2, and 3 being significantly higher than that in Comparative Example 2; although the discharge specific capacity and first efficiency of Examples 1 and 3 are lower than those in Comparative Example 2 due to the increase in single crystal particles, the electrode compaction density of Examples 1 and 3 is significantly improved, thereby achieving the purpose of improving the volume energy density of the lithium-ion battery; Examples 1 and 3 are significantly improved compared with Comparative Example 1, indicating that the preparation method provided by the present invention is superior to Comparative Example 1; the data of Example 2 show that large single crystals can also be normally prepared from two materials with different components.

[0075] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a layered large single crystal positive electrode material for a lithium ion battery, characterized in that: The steps include: After the ternary precursor is evenly mixed with the lithium source and the nano-sized aluminum source, the mixture is sintered once in air or oxygen atmosphere, and crushed to obtain a single crystal substrate with a particle size of 3 to 5 μm; the amount of the nano-sized aluminum source added is 500 to 1500 ppm; The single crystal substrate and the nano-sized cerium source are mixed evenly, and then secondary sintered in air or oxygen atmosphere, and crushed to obtain a coated and modified substrate; the amount of the nano-sized cerium source added is 500 to 2000 ppm; After the ternary precursor is evenly mixed with the lithium source and the nano-sized aluminum source, the mixture is sintered three times in air or oxygen atmosphere, and the single crystal coating material with a particle size of less than 2 μm is obtained after crushing; the addition amount of the nano-sized aluminum source is 500 to 1500 ppm; The coated and modified substrate and the single crystal coating material are evenly mixed in a mass ratio of 1:1 to 3, sintered four times in air or oxygen atmosphere, and crushed to obtain large single crystals with a particle size of 6 to 10 μm, namely, layered large single crystal positive electrode materials.

2. The method for preparing a layered large single crystal positive electrode material for a lithium ion battery according to claim 1, wherein: The D50 of the ternary precursor for preparing the single crystal substrate is 3 to 5 μm.

3. The method for preparing a layered large single crystal positive electrode material for a lithium ion battery according to claim 1, wherein: When preparing a single crystal substrate, the molar ratio of lithium element to the metal element in the ternary precursor is 1.03 to 1.07:

1.

4. The method for preparing a layered large single crystal positive electrode material for a lithium ion battery according to claim 1, wherein: The D50 of the ternary precursor for preparing the single crystal coating material is 0.5 to 2.5 μm.

5. The method for preparing a layered large single crystal positive electrode material for a lithium ion battery according to claim 1, wherein: When preparing the single crystal coating material, the molar ratio of lithium element to the metal element in the ternary precursor is 1.03-1.07:

1.

6. A layered large single crystal positive electrode material for lithium-ion batteries, characterized in that: The method is obtained by any one of claims 1 to 5.

7. Use of the layered large single crystal positive electrode material for lithium ion batteries according to claim 6 in lithium ion batteries.

8. The use according to claim 7, characterized in that: The layered large single crystal positive electrode material for lithium ion batteries is mixed with a conductive agent, a binder, and a solvent to form a slurry, which is coated on the surface of a current collector and dried to obtain a positive electrode; the positive electrode, negative electrode, electrolyte, and separator are assembled into a lithium ion battery.

9. A lithium-ion battery comprising a positive electrode, a negative electrode, an electrolyte and a separator, characterized in that: The positive electrode material used in the positive electrode is the layered large single crystal positive electrode material for lithium-ion batteries as described in claim 6.

10. The lithium-ion battery according to claim 9, wherein: The positive electrode comprises a current collector, an active layer is arranged on the surface of the current collector, and the active layer contains the layered large single crystal positive electrode material for the lithium ion battery, a conductive agent, and a binder.

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