Cathode material, its preparation method and lithium-ion battery containing the cathode material

Abstract

This application relates to cathode materials, their preparation methods, and lithium-ion batteries comprising the cathode material. The cathode material is nZnO·LiNi coated with ZnO and doped with Zn. a Co b Mn c Zn d O 2+d Where 0.0001 < n ≤ 0.1, 0.5 ≤ a < 1, 0.1 < b ≤ 0.3, 0.1 < c ≤ 0.3, a + b + c = 1, and 0.0001 < d ≤ 0.1. The doping and coating synergistic cathode material provided in this application, due to Zn... 2+ With an ionic radius similar to that of Ni ions, Zn occupies Ni ion sites in the cathode material, suppressing the collapse of the layered framework of nickel, cobalt, and manganese elements during lithium-ion insertion / extraction and reducing Li... + / Ni 2+ Cation mixing improves the cycle stability of lithium-ion batteries using this cathode. A one-step process, involving ball milling and mixing lithium salt, zinc acetate, and ternary precursors, conveniently and effectively synthesizes cathode materials with synergistic doping and coating, suitable for mass production.

Description

Technical Field

[0001] This application belongs to the field of materials technology, specifically relating to cathode materials, their preparation methods, and lithium-ion batteries containing the cathode materials. Background Technology

[0002] Lithium-ion batteries, due to their high energy density, are widely used in new energy vehicles, portable mobile devices, and other fields. In lithium-ion batteries, the cathode material contributes significantly to energy density. Currently, nickel-cobalt-manganese (NCM) ternary cathode materials with a layered structure are among the most promising cathode materials due to their high specific capacity. In NCM ternary cathode materials, nickel, as the main element participating in redox reactions, provides capacity by changing its valence state to induce lithium-ion insertion / extraction. During cycling, conventional NCM ternary cathode materials... 2+ Redox reactions occur, forming an interfacial phase that hinders lithium-ion and electron transport, leading to severe interface problems and poor cycle stability. High nickel content introduces significant interface problems into the cathode material. Firstly, during lithium-ion battery cycling, due to Ni… 2+ The radius of Li + Similar radii, partially unoxidized Ni 2+ Will migrate to Li + This creates sites that cause cation mixing, forming an insulating, disordered rock salt phase, which in turn hinders lithium-ion and electron transport. Furthermore, Ni in high-nickel NCM ternary cathode materials... 3+ Spontaneous reduction occurs, weakening the Ni-O bond and causing irreversible loss of lattice oxygen and active lithium. This irreversible consumption further accelerates the formation of rock salt phase on the particle surface, affecting the cycle life of lithium-ion batteries. In NCM ternary cathode materials, the layered framework composed of nickel, cobalt, and manganese collapses during lithium-ion insertion / extraction, resulting in low reversible discharge specific capacity. Ni is typically controlled through cation doping and surface coating. 2+ Content and location, stable cations and phase transitions. Summary of the Invention

[0003] This application provides a cathode material, a method for its preparation, and a lithium-ion battery comprising the cathode material. The cathode material provided in this application, with its synergistic doping and coating, possesses a ZnO coating layer with strong electrochemical stability, thus reducing the Ni content in the NCM ternary cathode during cycling. 2+ The low electronic / ionic conductivity phase formed by redox reactions optimizes interfacial properties. Furthermore, due to Zn... 2+ With an ionic radius similar to that of Ni ions, Zn occupies Ni ion sites in ternary cathode materials, suppressing the collapse of the layered framework of nickel, cobalt, and manganese elements during lithium-ion insertion / extraction and reducing Li ion degradation. + / Ni 2+Cation mixing improves the cycle stability of lithium-ion batteries using this cathode. The cathode material preparation method provided in this application utilizes a one-step process of ball milling and mixing lithium salt, zinc acetate, and ternary precursors to conveniently and effectively synthesize a synergistic doping and coating ternary cathode material suitable for mass production.

[0004] In one aspect, this application provides a cathode material, which is nZnO·LiNi coated with ZnO and doped with Zn. a Co b Mn c Zn d O 2+d , where 0.0001<n≤0.1, 0.5≤a<1, 0.1<b≤0.3, 0.1<c≤0.3, a+b+c=1, and 0.0001<d≤0.1.

[0005] In the implementation scheme of this application, 0.001 < n ≤ 0.1, 0.5 ≤ a < 0.8, 0.15 < b ≤ 0.3, 0.15 < c ≤ 0.3, a + b + c = 1, and 0.001 < d ≤ 0.05.

[0006] In an embodiment of this application, the cathode material is 0.009ZnO·LiNi. 0.5 Co 0.2 Mn 0.3 Zn 0.011 O 2.011 0.003ZnO·LiNi 0.8 Co 0.1 Mn 0.1 Zn 0.005 O 2.005 Or 0.04ZnO·LiNi 0.6 Co 0.2 Mn 0.2 Zn 0.06 O 2.06 .

[0007] On the other hand, this application provides a method for preparing the above-mentioned cathode material, the method comprising the following steps:

[0008] (1) Prepare solution A by mixing soluble nickel salt, soluble cobalt salt, and soluble manganese salt with water and / or ethanol, and prepare solution B by mixing NaOH with water and / or ethanol.

[0009] (2) Add solution A, ammonia water and solution B to the reaction vessel and stir to carry out the reaction until the average particle size of the formed particles is 0.1-10μm, then stop the reaction to obtain ternary precursor slurry;

[0010] (3) Remove the liquid and impurities from the ternary precursor slurry to obtain the ternary precursor;

[0011] (4) The lithium salt, zinc acetate and the ternary precursor were ball-milled and mixed to obtain a mixed precursor;

[0012] (5) The mixture precursor is sintered in an atmosphere of air and / or oxygen to obtain a cathode material coated with ZnO and doped with Zn.

[0013] In the embodiments of this application, in step (1), the soluble nickel salt, soluble cobalt salt, and soluble manganese salt are sulfates.

[0014] Optionally, in step (1), the molar ratio of nickel, cobalt and manganese in solution A is 0.5-1:0.1-0.3:0.1-0.3; the total cation concentration in solution A is 1-10 mol / L; and the total cation concentration in solution B is 1-10 mol / L.

[0015] In the embodiments of this application, in step (2), the feeding rates of solution A and solution B are 30-400 mL / min, respectively;

[0016] Optionally, in step (2), the flow rate of ammonia water is controlled so that the concentration of ammonia water in the reaction vessel is 3-10 g / L during the reaction; the flow rate of solution B is controlled so that the pH value in the reaction vessel is 11-12 during the reaction; the stirring speed is 200-1200 r / min; and the reaction temperature is 30-90℃.

[0017] In the embodiments of this application, in step (4), the lithium salt is at least one of lithium hydroxide, lithium hydroxide hydrate and lithium carbonate; the molar ratio of lithium element to ternary precursor in the lithium salt is 1-1.2:1; the molar ratio of zinc acetate to ternary precursor is 0.002-0.25:1;

[0018] Optionally, in step (4), the ball milling speed is 100-800 r / min; the ball milling time is 0.1-12 h.

[0019] In the embodiments of this application, in step (4), the lithium salt is lithium carbonate, and the lithium carbonate, zinc acetate and Ni 0.5 Co 0.2 Mn 0.3 The molar ratio of the O2 ternary precursor is 1.15:0.02:1; or

[0020] In step (4), the lithium salt is lithium hydroxide, and the lithium hydroxide, zinc acetate, and Ni 0.8 Co 0.1 Mn0.1 The molar ratio of the O2 ternary precursor is 1.2:0.008:1; or

[0021] In step (4), the lithium salt is lithium carbonate, and the lithium carbonate, zinc acetate, and Ni 0.6 Co 0.2 Mn 0.2 The molar ratio of the O2 ternary precursor is 1.05:0.1:1.

[0022] In the embodiments of this application, in step (5), the sintering is a two-stage sintering, the first stage sintering temperature is 200-700℃ and the sintering time is 1-10h, and the second stage sintering temperature is 800-1100℃ and the sintering time is 6-24h.

[0023] On the other hand, this application provides a lithium-ion battery comprising the above-described positive electrode material or a positive electrode material prepared by the above-described method.

[0024] The beneficial effects of this application are:

[0025] 1. This application provides a convenient and efficient one-step process for ball milling and mixing lithium salt, zinc acetate, and ternary precursor to synthesize a ternary cathode material with synergistic doping and coating, which is suitable for mass production;

[0026] 2. The doping and coating synergistic cathode material provided in this application, due to its highly electrochemically stable ZnO coating layer, can reduce the Ni content in the NCM ternary cathode during cycling. 2+ The low electronic / ionic conductivity phase formed by redox reactions optimizes interface properties.

[0027] 3. The cathode material with synergistic doping and coating provided in this application, due to Zn 2+ Ionic radius and Ni 2+ Due to their similar ionic composition, Zn occupies Ni ion sites in the cathode material, suppressing the collapse of the layered framework of nickel, cobalt, and manganese elements during lithium-ion insertion / extraction and reducing the degradation of Li ions. + / Ni 2+ Cation mixing improves the cycle stability of lithium-ion batteries using this cathode.

[0028] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application may be realized and obtained by means of the methods described in the description. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in detail below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined with each other.

[0030] This application provides a cathode material, which is nZnO·LiNi coated with ZnO and doped with Zn. a Co b Mn c Zn d O 2+d , where 0.0001<n≤0.1, 0.5≤a<1, 0.1<b≤0.3, 0.1<c≤0.3, a+b+c=1, and 0.0001<d≤0.1.

[0031] In the embodiments of this application, 0.001 < n ≤ 0.1, 0.5 ≤ a < 0.8, 0.15 < b ≤ 0.3, 0.15 < c ≤ 0.3, a + b + c = 1, and 0.001 < d ≤ 0.05.

[0032] In the embodiments of this application, the positive electrode material is 0.009ZnO·LiNi. 0.5 Co 0.2 Mn 0.3 Zn 0.011 O 2.011 0.003ZnO·LiNi 0.8 Co 0.1 Mn 0.1 Zn 0.005 O 2.005 Or 0.04ZnO·LiNi 0.6 Co 0.2 Mn 0.2 Zn 0.06 O 2.06 .

[0033] This application also provides a method for preparing the above-mentioned cathode material, the method comprising the following steps:

[0034] (1) Prepare solution A by mixing soluble nickel salt, soluble cobalt salt, and soluble manganese salt with water and / or ethanol, and prepare solution B by mixing NaOH with water and / or ethanol.

[0035] (2) Add solution A, ammonia water and solution B to the reaction vessel and stir to carry out the reaction until the average particle size of the formed particles is 0.1-10μm, then stop the reaction to obtain ternary precursor slurry;

[0036] (3) Remove the liquid and impurities from the ternary precursor slurry to obtain the ternary precursor;

[0037] (4) The lithium salt, zinc acetate and the ternary precursor were ball-milled and mixed to obtain a mixed precursor;

[0038] (5) The mixture precursor is sintered in an atmosphere of air and / or oxygen to obtain a cathode material coated with ZnO and doped with Zn.

[0039] In the embodiments of this application, in step (1), the soluble nickel salt, soluble cobalt salt, and soluble manganese salt are sulfates.

[0040] Optionally, in step (1), the molar ratio of nickel, cobalt and manganese in solution A is 0.5-1:0.1-0.3:0.1-0.3; the total cation concentration in solution A is 1-10 mol / L; and the total cation concentration in solution B is 1-10 mol / L.

[0041] In the embodiments of this application, in step (2), the feeding rates of solution A and solution B are 30-400 mL / min, respectively;

[0042] Optionally, in step (2), the flow rate of ammonia water is controlled so that the concentration of ammonia water in the reaction vessel is 3-10 g / L during the reaction; the flow rate of solution B is controlled so that the pH value in the reaction vessel is 11-12 during the reaction; the stirring speed is 200-1200 r / min; and the reaction temperature is 30-90℃.

[0043] In the embodiments of this application, in step (4), the lithium salt is at least one of lithium hydroxide, lithium hydroxide hydrate and lithium carbonate; the molar ratio of lithium element to ternary precursor in the lithium salt is 1-1.2:1; the molar ratio of zinc acetate to ternary precursor is 0.002-0.25:1;

[0044] Optionally, in step (4), the ball milling speed is 100-800 r / min; the ball milling time is 0.1-12 h.

[0045] In the embodiments of this application, in step (4), the lithium salt is lithium carbonate, and the lithium carbonate, zinc acetate, and Ni 0.5 Co 0.2 Mn 0.3 The molar ratio of the O2 ternary precursor is 1.15:0.02:1; or

[0046] In step (4), the lithium salt is lithium hydroxide, and the lithium hydroxide, zinc acetate, and Ni 0.8 Co 0.1 Mn 0.1 The molar ratio of the O2 ternary precursor is 1.2:0.008:1; or

[0047] In step (4), the lithium salt is lithium carbonate, and the lithium carbonate, zinc acetate, and Ni 0.6 Co 0.2 Mn 0.2 The molar ratio of the O2 ternary precursor is 1.05:0.1:1.

[0048] In the embodiments of this application, in step (5), the sintering is a two-stage sintering, the first stage sintering temperature is 200-700℃ and the sintering time is 1-10h, and the second stage sintering temperature is 800-1100℃ and the sintering time is 6-24h.

[0049] This application also provides a lithium-ion battery comprising the above-described positive electrode material or a positive electrode material prepared by the above-described method.

[0050] Example 1:

[0051] Nickel sulfate, cobalt sulfate, and manganese sulfate were mixed with water in a molar ratio of 0.5:0.2:0.3 to prepare solution A, with the total cation concentration controlled at 3 mol / L. NaOH was mixed with water to prepare solution B, with the total cation concentration controlled at 2 mol / L. Solutions A, 5 g / L ammonia, and solution B were added to a reaction vessel at a rate of 200 mL / min, maintaining the pH at 11, stirring at 220 r / min, and the reaction temperature at 45 °C. Stirring continued until the average particle size reached 3 μm, at which point the reaction was stopped, yielding Ni. 0.5 Co 0.2 Mn 0.3 O2 ternary precursor slurry; removal of Ni 0.5 Co 0.2 Mn 0.3 The liquid and impurities in the O2 ternary precursor slurry were removed to obtain the ternary precursor; lithium carbonate, zinc acetate and Ni were added in a molar ratio of 1.15:0.02:1. 0.5 Co 0.2 Mn 0.3 The O2 ternary precursor was ball-milled at 300 r / min for 2 h to obtain a mixed precursor; the mixed precursor was heated to 600 °C in air and held for 6 h, then heated to 900 °C and held for 12 h, and naturally cooled to obtain a cathode material 0.009ZnO·LiNi coated with Zn and doped with Zn. 0.5 Co 0.2 Mn 0.3 Zn 0.011 O 2.011 .

[0052] Example 2:

[0053] Nickel sulfate, cobalt sulfate, and manganese sulfate were mixed with water in a molar ratio of 0.8:0.1:0.1 to prepare solution A, with the total cation concentration controlled at 7 mol / L. NaOH was mixed with water to prepare solution B, with the total cation concentration controlled at 10 mol / L. Solutions A, 1 g / L ammonia, and solution B were added to a reaction vessel at a rate of 45 mL / min, maintaining the pH at 11, stirring at 690 r / min, and the reaction temperature at 70 °C. Stirring continued until the average particle size reached 0.5 μm, at which point the reaction was stopped, yielding Ni. 0.8 Co 0.1 Mn 0.1 O2 ternary precursor slurry; removal of Ni 0.8 Co 0.1 Mn 0.1 The liquid and impurities in the O2 ternary precursor slurry were removed to obtain the ternary precursor; lithium hydroxide, zinc acetate and Ni were added in a molar ratio of 1.2:0.008:1. 0.8 Co 0.1 Mn 0.1 The O2 ternary precursor was ball-milled at 600 r / min for 12 h to obtain a mixed precursor; the mixed precursor was heated to 300 °C in air and held for 2 h, then heated to 870 °C and held for 16 h, and naturally cooled to obtain a cathode material 0.003ZnO·LiNi coated with ZnO and doped with Zn. 0.8 Co 0.1 Mn 0.1 Zn 0.005 O 2.005 .

[0054] Example 3:

[0055] Nickel sulfate, cobalt sulfate, and manganese sulfate were mixed with water in a molar ratio of 0.6:0.2:0.2 to prepare solution A, with the total cation concentration controlled at 10 mol / L. NaOH was mixed with water to prepare solution B, with the total cation concentration controlled at 5 mol / L. Solutions A, 9.5 g / L ammonia, and solution B were added to a reaction vessel at a rate of 400 mL / min, maintaining the pH at 12, stirring at 1180 r / min, and the reaction temperature at 85 °C. Stirring continued until the average particle size reached 9 μm, at which point the reaction was stopped, yielding Ni. 0.6 Co 0.2 Mn 0.2 O2 ternary precursor slurry; removal of Ni 0.6 Co 0.2 Mn 0.2 The liquid and impurities in the O2 ternary precursor slurry were removed to obtain the ternary precursor; lithium carbonate, zinc acetate and Ni were added in a molar ratio of 1.05:0.1:1. 0.6 Co0.2 Mn 0.2 The O2 ternary precursor was ball-milled at 750 r / min for 0.5 h to obtain a mixed precursor; the mixed precursor was heated to 700 °C in air and held for 10 h, then heated to 1050 °C and held for 24 h, and naturally cooled to obtain a cathode material 0.04ZnO·LiNi coated with Zn and doped with Zn. 0.6 Co 0.2 Mn 0.2 Zn 0.06 O 2.06 .

[0056] Comparative Example 1:

[0057] Nickel sulfate, cobalt sulfate, and manganese sulfate were mixed with water in a molar ratio of 0.5:0.2:0.3 to prepare solution A, with the total cation concentration controlled at 3 mol / L. NaOH was mixed with water to prepare solution B, with the total cation concentration controlled at 2 mol / L. Solutions A, 5 g / L ammonia, and solution B were added to a reaction vessel at a rate of 200 mL / min, maintaining the pH at 11, stirring at 220 r / min, and the reaction temperature at 45 °C. Stirring continued until the average particle size reached 3 μm, at which point the reaction was stopped, yielding Ni. 0.5 Co 0.2 Mn 0.3 O2 ternary precursor slurry; removal of Ni 0.5 Co 0.2 Mn 0.3 The liquid and impurities in the O2 ternary precursor slurry were removed to obtain the ternary precursor; lithium carbonate and Ni were mixed in a molar ratio of 1.15:1. 0.5 Co 0.2 Mn 0.3 The O2 ternary precursor was ball-milled at 300 r / min for 2 h to obtain a mixed precursor; the mixed precursor was heated to 600 °C in air and held for 6 h, then heated to 900 °C and held for 12 h, and then naturally cooled to obtain LiNi. 0.5 Co 0.2 Mn 0.3 O2 ternary cathode material.

[0058] Comparative Example 2:

[0059] Nickel sulfate, cobalt sulfate, and manganese sulfate were mixed with water in a molar ratio of 0.5:0.2:0.3 to prepare solution A, with the total cation concentration controlled at 3 mol / L. NaOH was mixed with water to prepare solution B, with the total cation concentration controlled at 2 mol / L. Solutions A, 5 g / L ammonia, and solution B were added to a reaction vessel at a rate of 200 mL / min, maintaining the pH at 11, stirring at 220 r / min, and the reaction temperature at 45 °C. Stirring continued until the average particle size reached 3 μm, at which point the reaction was stopped, yielding Ni. 0.5 Co 0.2 Mn 0.3 O2 ternary precursor slurry; removal of Ni 0.5 Co 0.2 Mn 0.3 The liquid and impurities in the O2 ternary precursor slurry were removed to obtain the ternary precursor; lithium carbonate and Ni were mixed in a molar ratio of 1.15:1. 0.5 Co 0.2 Mn 0.3 The O2 ternary precursor was ball-milled at 300 r / min for 2 h to obtain a mixed precursor; the mixed precursor was heated to 600 °C in air and held for 6 h, then heated to 900 °C and held for 12 h, and then naturally cooled to obtain LiNi. 0.5 Co 0.2 Mn 0.3 O2 ternary cathode material. LiNi with a molar ratio of 1000:3.842. 0.5 Co 0.2 Mn 0.3 O and ZnO were ball-milled at 300 r / min for 3 h. After ball milling, the mixture was taken out and heated to 600 °C at a heating rate of 5 °C / min and held for 2 h. Then, it was heated to 800 °C at a heating rate of 1 °C / min and held for 10 h. The resulting product was LiNi coated with ZnO. 0.5 Co 0.2 Mn 0.3 O2 cathode material.

[0060] Comparative Example 3

[0061] Nickel sulfate, cobalt sulfate, and manganese sulfate were mixed with water in a molar ratio of 0.5:0.2:0.3 to prepare solution A, with the total cation concentration controlled at 3 mol / L. NaOH was mixed with water to prepare solution B, with the total cation concentration controlled at 2 mol / L. Solutions A, 5 g / L ammonia, and solution B were added to a reaction vessel at a rate of 200 mL / min, maintaining the pH at 11, stirring at 220 r / min, and the reaction temperature at 45 °C. Stirring continued until the average particle size reached 3 μm, at which point the reaction was stopped, yielding Ni. 0.5 Co 0.2Mn 0.3 O2 ternary precursor slurry; removal of Ni 0.5 Co 0.2 Mn 0.3 The liquid and impurities in the O2 ternary precursor slurry were removed to obtain the ternary precursor; lithium carbonate, ZnO and Ni were added in a molar ratio of 1.15:0.02:1. 0.5 Co 0.2 Mn 0.3 The O2 ternary precursor was ball-milled at 300 r / min for 2 h to obtain a mixed precursor; the mixed precursor was heated to 600 °C in air and held for 6 h, then heated to 900 °C and held for 12 h, and naturally cooled to obtain ZnO and LiNi. 0.5 Co 0.2 Mn 0.3 O2 and LiNi 0.5 Co 0.2 Mn 0.3 Zn 0.005 O 2.005 Blended cathode material.

[0062] Performance testing

[0063] Test Example 1

[0064] Using the positive electrode material synthesized in Example 1 and a lithium metal negative electrode, along with lithium-ion battery electrolyte, coin cells were assembled and their cycle performance was tested at 0.1C and 1C. At 0.1C, the battery's first-cycle discharge specific capacity was 178 mAh / g, with an first-cycle efficiency of 95%, and a capacity retention of 79% after 100 cycles. At 1C, the first-cycle discharge specific capacity was 169 mAh / g, with an first-cycle efficiency of 85%, and a capacity retention of 88% after 100 cycles.

[0065] Test Example 2

[0066] Using the positive electrode material synthesized in Example 2 and a lithium metal negative electrode, along with lithium-ion battery electrolyte, coin cells were assembled and their cycle performance was tested at 0.1C and 1C. At 0.1C, the battery's first-cycle discharge specific capacity was 184 mAh / g, with an first-cycle efficiency of 90%, and a capacity retention of 85% after 100 cycles. At 1C, the first-cycle discharge specific capacity was 166 mAh / g, with an first-cycle efficiency of 82%, and a capacity retention of 80% after 100 cycles.

[0067] Test Example 3

[0068] Using the positive electrode material synthesized in Example 3 and a lithium metal negative electrode, along with lithium-ion battery electrolyte, coin cells were assembled and their cycle performance was tested at 0.1C and 1C. At 0.1C, the battery's first-cycle discharge specific capacity was 177 mAh / g, with an first-cycle efficiency of 96%, and a capacity retention rate of 81% after 100 cycles. At 1C, the first-cycle discharge specific capacity was 161 mAh / g, with an first-cycle efficiency of 83%, and a capacity retention rate of 84% after 100 cycles.

[0069] Comparison Test Example 1

[0070] Using the LiNi synthesized in Comparative Example 1 0.5 Co 0.2 Mn 0.3 O2 ternary cathode material and lithium metal anode, combined with lithium-ion battery electrolyte, were used to assemble coin cells. The cycle performance of the cells was tested at 0.1C and 1C. At 0.1C, the initial discharge specific capacity was 164 mAh / g, with an initial efficiency of 84%, and a capacity retention of 35% after 100 cycles. At 1C, the initial discharge specific capacity was 132 mAh / g, with an initial efficiency of 73%, and a capacity retention of 55% after 100 cycles.

[0071] Comparison Test Example 2

[0072] The ZnO-coated LiNi synthesized in Comparative Example 2 0.5 Co 0.2 Mn 0.3 A coin cell was assembled using an O2 positive electrode and a lithium metal negative electrode, along with lithium-ion battery electrolyte. The battery's cycle performance was tested at 0.1C and 1C. At 0.1C, the initial discharge specific capacity was 167 mAh / g, with an initial efficiency of 87%, and a capacity retention of 66% after 100 cycles. At 1C, the initial discharge specific capacity was 144 mAh / g, with an initial efficiency of 75%, and a capacity retention of 64% after 100 cycles.

[0073] Comparison Test Case 3

[0074] ZnO and LiNi synthesized in Comparative Example 3 were used 0.5 Co 0.2 Mn 0.3 O2 and LiNi 0.5 Co 0.2 Mn 0.3 Zn 0.005 O 2.005A blended positive electrode and a lithium metal negative electrode were used, along with lithium-ion battery electrolyte, to assemble coin cells. The cycle performance of the cells was tested at 0.1C and 1C. At 0.1C, the initial discharge specific capacity was 168 mAh / g, with an initial efficiency of 87%, and a capacity retention of 69% after 100 cycles. At 1C, the initial discharge specific capacity was 146 mAh / g, with an initial efficiency of 76%, and a capacity retention of 65% after 100 cycles.

[0075] Table 1 below lists the cycle performance results of Test Examples 1-3 using the cathode materials of Examples 1-3 of this application and Comparative Test Examples 1-2 using the cathode materials of Comparative Examples 1-2 at 0.1C and 1C.

[0076] Table 1

[0077]

[0078] As can be seen from the test results in Table 1, compared with the comparative test examples 1-3 which use the cathode materials synthesized in comparative examples 1-3, the coin cells assembled using the cathode materials synthesized in examples 1-3 of this application have better cycle performance at 0.1C and 1C.

[0079] Although the embodiments disclosed in this application are as described above, the content described is merely for the purpose of understanding this application and is not intended to limit this application. Any person skilled in the art to which this application pertains may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application; however, the scope of patent protection of this application shall still be determined by the scope defined in the appended claims.

Claims

1. A positive electrode material, characterized in that, The cathode material is nZnO•LiNi coated with ZnO and doped with Zn. a Co b Mn c Zn d O 2+d Where 0.0001 < n ≤ 0.1, 0.5 ≤ a < 1, 0.1 < b ≤ 0.3, 0.1 < c ≤ 0.3, a + b + c = 1, 0.0001 < d ≤ 0.1, The positive electrode material is prepared by the following steps: (1) Prepare solution A by mixing soluble nickel salt, soluble cobalt salt, and soluble manganese salt with water and / or ethanol, and prepare solution B by mixing NaOH with water and / or ethanol. (2) Add solution A, ammonia water and solution B into the reaction vessel and stir to carry out the reaction until the average particle size of the formed particles is 0.1-10 μm, then stop the reaction to obtain ternary precursor slurry; (3) Remove the liquid and impurities from the ternary precursor slurry to obtain the ternary precursor; (4) The lithium salt, zinc acetate and the ternary precursor were ball-milled and mixed to obtain a mixed precursor; (5) The mixture precursor is sintered in an atmosphere of air and / or oxygen to obtain a cathode material coated with ZnO and doped with Zn.

2. The cathode material according to claim 1, wherein, 0.001<n≤0.1, 0.5≤a<0.8, 0.15<b≤0.3, 0.15<c≤0.3, a+b+c=1, 0.001<d≤0.

05.

3. The cathode material according to claim 1, wherein, The cathode material is 0.009ZnO•LiNi. 0.5 Co 0.2 Mn 0.3 Zn 0.011 O 2.011 0.003ZnO•LiNi 0.8 Co 0.1 Mn 0.1 Zn 0.005 O 2.005 Or 0.04ZnO•LiNi 0.6 Co 0.2 Mn 0.2 Zn 0.06 O 2.06 .

4. The cathode material according to claim 1, wherein, In step (1), the soluble nickel salt, soluble cobalt salt, and soluble manganese salt are sulfates. In step (1), the molar ratio of nickel, cobalt and manganese in solution A is 0.5-1:0.1-0.3:0.1-0.3; the total cation concentration in solution A is 1-10 mol / L; and the total cation concentration in solution B is 1-10 mol / L.

5. The cathode material according to claim 1, wherein, In step (2), the feeding rates of solution A and solution B are 30-400 mL / min, respectively; In step (2), the flow rate of ammonia water is controlled so that the concentration of ammonia water in the reaction vessel is 3-10 g / L during the reaction; the flow rate of solution B is controlled so that the pH value in the reaction vessel is 11-12 during the reaction; the stirring speed is 200-1200 r / min; and the reaction temperature is 30-90℃.

6. The cathode material according to claim 1, wherein, In step (4), the lithium salt is at least one of lithium hydroxide, lithium hydroxide hydrate, and lithium carbonate; the molar ratio of lithium element in the lithium salt to the ternary precursor is 1-1.2:1; the molar ratio of zinc acetate to the ternary precursor is 0.002-0.25:1; In step (4), the ball milling speed is 100-800 r / min; the ball milling time is 0.1-12 h.

7. The cathode material according to claim 6, wherein, In step (4), the lithium salt is lithium carbonate, and the lithium carbonate, zinc acetate, and Ni 0.5 Co 0.2 Mn 0.3 The molar ratio of the O2 ternary precursor is 1.15:0.02:1; or, In step (4), the lithium salt is lithium hydroxide, and the lithium hydroxide, zinc acetate, and Ni 0.8 Co 0.1 Mn 0.1 The molar ratio of the O2 ternary precursor is 1.2:0.008:1; or, In step (4), the lithium salt is lithium carbonate, and the lithium carbonate, zinc acetate, and Ni 0.6 Co 0.2 Mn 0.2 The molar ratio of the O2 ternary precursor is 1.05:0.1:

1.

8. The cathode material according to any one of claims 1 or 4-7, wherein, In step (5), the sintering is a two-stage sintering. The first stage sintering temperature is 200-700℃ and the sintering time is 1-10h. The second stage sintering temperature is 800-1100℃ and the sintering time is 6-24h.

9. A lithium-ion battery comprising the positive electrode material according to any one of claims 1-8.

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