A high-nickel ternary positive electrode material, a preparation method and application thereof

Abstract

The application provides a high-nickel ternary positive electrode material, which comprises a core and a coating layer, the structure of the core is whisker arrangement with internal order and outer disorder, and the outer layer of the core is further doped with an additive; the ionic radius of a doped element in the additive is 80*10 ‑12 ~120*10 ‑12 m. The high-nickel ternary positive electrode material provided by the application has a core with internal order and outer disorder, which guarantees lithium ion diffusion and improves particle strength; meanwhile, the surface strength is improved by introducing ion doping with moderate radius, which effectively improves the particle strength of the ternary positive electrode material as a supporting structure, effectively improves the comprehensive performance such as cycle and gas production of the positive electrode material, and the preparation method is simple, which is beneficial to rapid commercialization.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and particularly relates to a high-nickel ternary positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] At present, high-nickel ternary lithium ion batteries, as green batteries with high energy density, no memory effect and excellent performance of high working voltage platform, are more and more widely concerned. The positive electrode material is an important component of the lithium ion battery. It is of great significance for the development and application of the lithium ion battery to prepare a positive electrode material with high safety performance, high specific capacity and stable cycle performance. However, although the high-nickel ternary material has high capacity, the high-nickel ternary material has less Co and Mn elements with stable structure. In the cycle process, stress is easily concentrated due to internal shrinkage and expansion. The particles are prone to cracking and pulverization from the particle surface in the process of rolling and cycling, resulting in exposure of the fresh interface, consumption of electrolyte, and problems such as cycle diving, increased internal resistance and battery bulging. Therefore, it is particularly important to improve the particle strength of the ternary material to improve the particle breakage. SUMMARY

[0003] Therefore, the technical problem to be solved by the application is to provide a high-nickel ternary positive electrode material and a preparation method and application thereof. The high-nickel ternary positive electrode material provided by the application has high strength and can effectively improve the comprehensive performance such as cycle and gas production of the positive electrode material.

[0004] The application provides a high-nickel ternary positive electrode material, which comprises a core and a coating layer. The structure of the core is a whisker arrangement with an internal order and an external disorder. The outer layer of the core is further doped with an additive. The ion radius of the doped element in the additive is 80*10 -12 ~ 120*10 -12 m.

[0005] Preferably, the doped element is selected from one or more of Y 3+ , Ce 3+ , Sr 2+ .

[0006] Preferably, the coating layer is lithium borate.

[0007] Preferably, the general formula of the high-nickel ternary positive electrode material is LiNi x Co y A 1-x-y O2, wherein 0.6≦x≦1, 0≦y≦0.4, and A is at least one element selected from Mn, Al, Y, Ce and Sr.

[0008] The application further provides a preparation method of the high-nickel ternary positive electrode material.

[0009] A) mixing a nickel source compound and other metal source compounds, a precipitant and water under a protective atmosphere, then adding a complexing agent, and under the conditions of heating, pH of 11-12, ammonia value of 2.5-3.2 g / L, primary nucleation is carried out to obtain a precursor core internal structure with ordered whisker arrangement;

[0010] Then, under the conditions of adjusting pH to 9-11, ammonia value to 3.2-3.8 g / L, continuing nucleation is carried out to obtain a precursor with ordered internal structure and disordered outer layer whisker arrangement structure;

[0011] B) mixing the precursor, a lithium source compound and an additive, then pre-sintering and sintering to obtain a ternary positive electrode material core;

[0012] C) mixing the ternary positive electrode material core with a coating agent and sintering to obtain a high-nickel ternary positive electrode material.

[0013] Preferably, the nickel source compound is selected from one or more of nickel sulfate, nickel chloride and nickel nitrate;

[0014] The other metal source compound is selected from one or more of a cobalt source compound and a manganese source compound; the cobalt source compound is selected from one or more of cobalt sulfate, cobalt chloride and cobalt nitrate; the manganese source compound is selected from one or more of manganese sulfate, manganese chloride and manganese nitrate;

[0015] The precipitant is selected from one or more of sodium hydroxide, magnesium hydroxide and potassium hydroxide;

[0016] The complexing agent is selected from ammonia water.

[0017] Preferably, the particle size of the primary nucleation is 2-5 μm, and the particle size of the precursor is 9-15 μm.

[0018] Preferably, in step B), the lithium source compound is selected from one or more of lithium hydroxide and lithium carbonate;

[0019] The additive is selected from one or more of CeO2, Y2O3, SrO, CeF3, Y(OH)3, Sr(OH)2 and Ce(OH)4;

[0020] The sintering has a temperature rising rate of 1-3 ℃ / min, a temperature of 700-850 ℃ and a time of 8-14 h.

[0021] Preferably, in step C), the coating agent is selected from one or more of H3BO3, LiBO2, Li2B4O7 and Li3BO3;

[0022] The sintering temperature increasing rate is 1-3 DEG C / min, the temperature is 260-360 DEG C, and the time is 8-14h.

[0023] The application further provides a lithium ion battery comprising the high-nickel ternary positive electrode material.

[0024] Compared with the prior art, the application provides a high-nickel ternary positive electrode material comprising a core and a coating layer, wherein the structure of the core is a whisker arrangement with internal order and external disorder, and the outer layer of the core is further doped with an additive, and the ion radius of the doping element in the additive is 80*10 -12 ~120*10 -12 m. The high-nickel ternary positive electrode material provided by the application has a core with internal order and external disorder, which guarantees lithium ion diffusion and improves particle strength, and the surface strength is improved by introducing ion doping with a moderate radius, which effectively improves the particle strength of the ternary positive electrode material and improves the comprehensive performance of the positive electrode material, such as cycle and gas production, and the preparation method is simple and conducive to rapid commercialization. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 SEM images of high-nickel positive electrode materials prepared for examples and comparative examples;

[0026] Figure 2 A cross-sectional view of the high-nickel positive electrode material prepared in Example 1 of the application;

[0027] Figure 3 A cross-sectional view of the high-nickel positive electrode material prepared in Comparative Example 5 of the application;

[0028] Figure 4 An EDS spectrum of the high-nickel positive electrode material prepared in Example 1 of the application. DETAILED DESCRIPTION

[0029] The application provides a high-nickel ternary positive electrode material comprising a core and a coating layer, wherein the structure of the core is a whisker arrangement with internal order and external disorder, and the outer layer of the core is further doped with an additive, and the ion radius of the doping element in the additive is 80*10 -12 ~120*10 -12 m.

[0030] The high-nickel ternary positive electrode material provided by the application comprises a core, wherein the structure of the core is a whisker arrangement with internal order and external disorder. The volume D50 of the core is 9-15 mu m.

[0031] The outer layer of the core is further doped with an additive, and the ion radius of the doping element in the additive is 80*10 -12 ~120*10 -12m.In the ion radius range, as a support structure effectively improves the particle strength of the ternary positive electrode material while not hindering the interlayer transport of lithium ions. In the range of ion radius doping, more than 80% of the doping elements are distributed on the outer surface of the core, and within 20% are diffused to the inner core grain boundary of the core. Among them, the thickness of the outer surface accounts for 50% to 70% of the core radius, and the radius of the inner core grain boundary accounts for 30% to 50% of the core radius.

[0032] The introduced doping ions, if the radius is very small, are easy to diffuse and are uniformly dispersed in the core, if the radius is very large, the diffusion is difficult, and basically gathers on the outer surface of the core. Introduce ions with moderate radius, most of which are concentrated on the outer surface to improve the particle strength, while a small amount of which diffuses to the inner core grain boundary to provide nucleation points for the nucleation of the positive electrode, and further promotes the formation of an internal ordered structure.

[0033] In the present application, the doping element of the additive is selected from one or more of Ce, Y, and Sr.

[0034] The high-nickel ternary positive electrode material provided by the present application further comprises a coating layer, and in the present application, the coating layer is lithium borate. The thickness of the coating layer is 1-50 nm.

[0035] The general formula of the high-nickel ternary positive electrode material is LiNi x Co y A 1-x-y O2, wherein: 0.6≦x≦1, 0≦y≦0.4, A is at least one element selected from Mn, Al, Y, Ce, and Sr.

[0036] The present application also provides a preparation method of the above high-nickel ternary positive electrode material, comprising the following steps:

[0037] A) Under the condition of a protective atmosphere, mix a nickel source compound and other metal source compounds, a precipitating agent, and water, then add a complexing agent, and under the condition of heating, pH of 11-12, and ammonia value of 2.5-3.2 g / L, preliminarily nucleate to obtain a precursor core internal structure with ordered whisker arrangement;

[0038] Then, continue to nucleate under the condition of adjusting the pH to 9-11 and the ammonia value to 3.2-3.8 g / L to obtain a precursor with an internal ordered and outer unordered whisker arrangement structure;

[0039] B) Mix the precursor, a lithium source compound, and an additive, then pre-sinter, and then sinter to obtain a ternary positive electrode material core;

[0040] C) Mix the ternary positive electrode material core with a coating agent and sinter to obtain a high-nickel ternary positive electrode material.

[0041] The present application first prepares a precursor. Nucleation is first performed at high pH and low ammonia value, promoting directional growth, and the nucleated particles are injected into an environment of low pH and high ammonia value, increasing the disorder degree of the particle surface, to obtain a precursor with ordered interior and disordered exterior.

[0042] Specifically, under the condition of a protective atmosphere, a nickel source compound and other metal source compounds, a precipitant and water are mixed, and then a complexing agent is added, and primary nucleation is performed under heating, pH of 11-12, preferably 11, 11.5, 12, or any value between 11-12, ammonia value of 2.5-3.2 g / L, preferably 2.5, 2.7, 3.0, 3.2, or any value between 2.5-3.2 g / L, to obtain a precursor core internal structure with ordered whisker arrangement;

[0043] Then, under the condition of adjusting the pH to 9-11, preferably 9, 10, 11, or any value between 9-11, and the ammonia value to 3.2-3.8 g / L, preferably 3.2, 3.5, 3.6, 3.8, or any value between 3.2-3.8 g / L, continuous nucleation is performed to obtain a precursor with ordered interior and disordered outer layer whisker arrangement structure.

[0044] Specifically, the reaction solution containing the precursor core internal structure with ordered whisker arrangement is added to continue nucleation under the condition of pH of 9-11 and ammonia value of 3.2-3.8 g / L, to obtain a precursor with ordered interior and disordered outer layer whisker arrangement structure.

[0045] The nickel source compound is selected from one or more of nickel sulfate, nickel chloride, and nickel nitrate;

[0046] The other metal source compound is selected from one or more of cobalt source compound and manganese source compound; the cobalt source compound is selected from one or more of cobalt sulfate, cobalt chloride, and cobalt nitrate; the manganese source compound is selected from one or more of manganese sulfate, manganese chloride, and manganese nitrate;

[0047] The precipitant is selected from one or more of sodium hydroxide, magnesium hydroxide, and potassium hydroxide;

[0048] The complexing agent is selected from ammonia water;

[0049] The protective atmosphere is selected from nitrogen.

[0050] The particle size of the primary nucleation is 3 μm, and the particle size of the precursor is 10 μm.

[0051] The heating temperature is 55-70℃, preferably 55, 60, 65, 70, or any value between 55-70℃.

[0052] After the preparation of the precursor, washing is performed using washing water having a temperature of 55-75°C, preferably 55, 60, 65, 70, 75, or any value between 55-75°C, and drying is performed under conditions of 140-180°C, preferably 140, 150, 160, 170, 180, or any value between 140-180°C, to obtain the product.

[0053] In some embodiments of the present application, the precursor is Ni 0.83 Co 0.06 Mn 0.11 (OH)2.

[0054] In the present application, the method for washing and drying is not particularly limited, and any method known to those skilled in the art can be used. In the present application, the equipment for washing is selected from filter press, centrifuge and water washing and drying integrated machine, and the equipment for drying is selected from oven, tray dryer, rotary kiln, flash dryer or spray dryer.

[0055] The present application adjusts the pH and ammonia value during the preparation of the precursor, to obtain a precursor with ordered interior and disordered exterior, to strengthen the surface of the particles, to strengthen the surface of the ternary material by doping with elements with appropriate radius, to improve the particle strength of the ternary material, to improve the storage and cycle cracking problems, to effectively improve the storage gas production and cycle retention rate of the ternary material, and to facilitate industrial production.

[0056] Next, the precursor, lithium source compound and additive are mixed and pre-sintered, and then sintered, to obtain a ternary positive electrode material core.

[0057] The lithium source compound is selected from one or more of lithium hydroxide and lithium carbonate;

[0058] The additive is selected from one or more of CeO2, Y2O3, SrO, CeF3, Y(OH)3, Sr(OH)2, and Ce(OH)4;

[0059] The pre-sintering temperature is 400-650°C, preferably 400, 450, 500, 550, 600, 650, or any value between 400-650°C, and the pre-sintering time is 5-12h, preferably 5, 6, 7, 8, 9, 10, 11, 12, or any value between 5-12h.

[0060] The sintering temperature is 700-850 DEG C, preferably 700, 750, 800, 850, or any value between 700-850 DEG C, and the time is 8-14h, preferably 8, 10, 12, 14, or any value between 8-14h.

[0061] Finally, the ternary positive electrode material core is mixed with the coating agent and sintered to obtain the high-nickel ternary positive electrode material.

[0062] The coating agent is selected from one or more of H3BO3, LiBO2, Li2B4O7 and Li3BO3.

[0063] The sintering temperature is 260-360 DEG C, preferably 260, 280, 300, 320, 340, 350, 360, or any value between 260-360 DEG C, and the time is 8-14h, preferably 8, 10, 12, 14, or any value between 8-14h.

[0064] The application also provides a lithium ion battery comprising the high-nickel ternary positive electrode material.

[0065] The high-nickel ternary positive electrode material has an internal ordered and external disordered core, which ensures lithium ion diffusion and improves particle strength, and the surface strength is improved by introducing ions with moderate radius, which effectively improves the particle strength of the ternary positive electrode material and improves the comprehensive performance of the positive electrode material such as cycle and gas production, and the preparation method is simple and conducive to rapid commercialization.

[0066] In order to further understand the application, the application provides a high-nickel ternary positive electrode material, a preparation method and application thereof, and the protection scope of the application is not limited by the following examples.

[0067] Example 1.

[0068] First, nucleation is carried out at a high pH value of 11.5 and a low ammonia value of 3.0g / L to promote directional growth, and the nucleated particles are injected into an environment with a low pH value of 10 and a high ammonia value of 3.5g / L to grow, thereby improving the disorder degree of the particle surface, and obtaining an internal ordered and external disordered precursor.

[0069] Specifically, the reactor is connected with a certain amount of nitrogen gas with purity ≥99% for protection, a nickel-cobalt-manganese sulfate solution (total concentration of metal ions is 1.5 mol / L, wherein the concentration of nickel ions is 1.2450 mol / L, the concentration of cobalt ions is 0.0900 mol / L, and the concentration of manganese ions is 0.165 mol / L) and 10.8 mol / L of sodium hydroxide solution are added into the reactor, under the conditions of a reaction temperature of 60 ℃ and pH = 11.5, 10 mol / L of ammonia water is introduced, the ammonia value is 3.0 g / L, the particle size reaches 3 μm, the pH is adjusted to 10, the ammonia value is 3.5 g / L, when the particle size D50 is about 10 μm, then washing water with a water temperature of 65 ℃ is used for washing and drying under the condition of 160 ℃, and the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2.

[0070] In a 4L high-speed mixer, 1 kg of the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2 prepared by the above method is added, 475 g of lithium hydroxide monohydrate and 2.5 g of CeO2 are added according to the molar ratio of the lithiumation coefficient 1:1.05, and stirring and mixing are performed at 300 rpm for 120 min. It is put into a sagger, an oxygen atmosphere (oxygen concentration ≥80%) is introduced, pre-sintering is performed at 600 ℃, then sintering is performed at 750 ℃ for 12 h, it is cooled to room temperature, then it is washed with water at 1:1 for 10 min, then centrifugation is performed under a centrifuge at 1000 rpm for 15 min, then drying is performed in an oven at 140 ℃ for 5 h, the high-nickel ternary material dried material is added into a planetary ball mill, zirconia ball milling beads are used, and the ball-to-material ratio is controlled to be 1:3. Then, 5 g of H3BO3 is added, after ball milling at 300 rpm for 3 h, the ball milling beads and the ball milling material are separated, the two ingredients are put into a sagger, an oxygen atmosphere (oxygen concentration ≥80%) is introduced, and sintering is performed at 350 ℃ for 12 h. The secondary particles with excellent grain strength and grain are obtained, and a battery with good cycle retention rate and excellent gas production performance can be prepared.

[0071] Referring to Figure 1 , Figure 1 SEM images of the high-nickel positive electrode materials prepared in the examples and comparative examples, Figure 1 1-1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 in the SEM (50K times) images of the high-nickel positive electrode materials prepared in the examples 1 / 2 / 3 / 4 of the application and comparative examples 1 / 2 / 3 / 4 / 5, respectively;

[0072] Figure 2 The cross-sectional view of the high-nickel positive electrode material prepared in the example 1 of the application; Figure 3 The cross-sectional view of the high-nickel positive electrode material prepared in the comparative example 5.Figure 2 and Figure 3 It can be seen that the high-nickel positive electrode material of Example 1 is internally ordered and externally disordered; the high-nickel positive electrode material of Comparative Example 5 is internally and externally ordered.

[0073] Figure 4 The EDS spectrum of the high-nickel positive electrode material prepared in Example 1 is shown in Figure 1. Figure 4 It can be seen that the doped Ce is mainly concentrated on the outer surface of the positive electrode particles, and more than 80% of the doped elements are distributed on the outer surface of the core.

[0074] Example 2.

[0075] First, nucleate at a high pH value of 11.5 and a low ammonia value of 3.0 g / L to promote directional growth, inject the nucleated particles into an environment with a low pH value of 10 and a high ammonia value of 3.5 g / L for growth, and improve the disorder degree of the particle surface, to obtain a precursor with internal order and external disorder. For specific preparation methods, see Example 1.

[0076] Add 1 kg of the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2 prepared by the above method into a 4L high-speed mixer, and add lithium hydroxide monohydrate 475 g and 2.5 g of Y2O3 in a molar ratio of 1:1.05, and stir and mix at 300 rpm for 120 min. Put into a crucible, and introduce an oxygen atmosphere (oxygen concentration ≥80%), and pre-sinter at 600°C for 8h, then increase the temperature to 750°C for sintering for 12h, and cool to room temperature, then wash with water at a ratio of 1:1 for 10 min, then centrifuge at 1000 rpm for 15 min, then dry in an oven at 140°C for 5h, and add the dried high-nickel ternary material into a planetary ball mill, use zirconia ball milling beads, and control the ball-to-material ratio to be 1:3. Then, add 5g of H3BO3, and ball mill at 300 rpm for 3h, then separate the ball milling beads and the ball milling material, and put the two ingredients into a crucible, introduce an oxygen atmosphere (oxygen concentration ≥80%), and sinter at 350°C for 12h. The secondary particles with excellent grain strength are obtained, and the battery with good cycle retention rate and excellent gas production performance can be prepared.

[0077] Example 3.

[0078] First, nucleate at a high pH value of 11.5 and a low ammonia value of 3.0 g / L to promote directional growth, inject the nucleated particles into an environment with a low pH value of 10 and a high ammonia value of 3.5 g / L for growth, and improve the disorder degree of the particle surface, to obtain a precursor with internal order and external disorder. For specific preparation methods, see Example 1.

[0079] Add 1 kg of the precursor Ni 0.83 Co0.06 Mn 0.11 (OH)2, 475g of lithium hydroxide monohydrate and 2.5g of SrO were added in a molar ratio of 1:1.05 according to the lithiumation coefficient, and stirred at 300 rpm for 120 min. Put into a crucible, and pre-sintered at 600°C for 8h in an oxygen atmosphere (oxygen concentration ≥ 80%), then sintered at 750°C for 12h, cooled to room temperature, then washed with water at a ratio of 1:1 for 10 min, then centrifuged at 1000 rpm for 15 min, and then dried in an oven at 140°C for 5h. The high-nickel ternary material dried material was added into a planetary ball mill, and zirconium oxide grinding beads were used, with a ball-to-material ratio controlled at 1:3. Then, 5g of H3BO3 was added, and after ball milling at 300 rpm for 3h, the grinding beads and the grinding material were separated, and the two ingredients were put into a crucible, sintered at 350°C for 12h in an oxygen atmosphere (oxygen concentration ≥ 80%). The secondary particles of grains with excellent particle strength were obtained, and a battery with good cycle retention rate and excellent gas production performance can be prepared.

[0080] Example 4.

[0081] First, nucleation was performed at a high pH value of 11.5 and a low ammonia value of 3.0g / L to promote the directional growth of the particles, and then the nucleated particles were injected into an environment with a low pH value of 10 and a high ammonia value of 3.5g / L for growth, thereby increasing the disorder degree of the particle surface, obtaining a precursor with an ordered interior and a disordered exterior. The specific preparation method is described in Example 1.

[0082] In a 4L high-speed mixer, 1kg of the precursor prepared by the above method was added. 0.83 Co 0.06 Mn 0.11 (OH)2, 475g of lithium hydroxide monohydrate and 2.8g of CeF3 were added in a molar ratio of 1:1.05 according to the lithiumation coefficient, and stirred at 300 rpm for 120 min. Put into a crucible, and pre-sintered at 600°C for 8h in an oxygen atmosphere (oxygen concentration ≥ 80%), then sintered at 750°C for 12h, cooled to room temperature, then washed with water at a ratio of 1:1 for 10 min, then centrifuged at 1000 rpm for 15 min, and then dried in an oven at 140°C for 5h. The high-nickel ternary material dried material was added into a planetary ball mill, and zirconium oxide grinding beads were used, with a ball-to-material ratio controlled at 1:3. Then, 5g of H3BO3 was added, and after ball milling at 300 rpm for 3h, the grinding beads and the grinding material were separated, and the two ingredients were put into a crucible, sintered at 350°C for 12h in an oxygen atmosphere (oxygen concentration ≥ 80%). The secondary particles of grains with excellent particle strength were obtained, and a battery with good cycle retention rate and excellent gas production performance can be prepared.

[0083] Comparative Example 1.

[0084] First nucleation at high pH value 11.5 and low ammonia value 3.0 g / L, promote its directional growth, the nucleation of the particles into the low pH value 10 and high ammonia value 3.5 g / L environment to grow, improve the disorder degree of particle surface, get internal order external disorder precursor, see example 1 for specific preparation method.

[0085] In 4L high mixer, add 1 kg of precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, according to the lithium coefficient molar ratio 1:1.05, add lithium hydroxide monohydrate 475g, stirring mixed 120min. Put into the box, oxygen atmosphere (oxygen concentration ≥ 80%), pre-sintering at 600℃ for 8h, then heated to 750℃ sintering 12h, cooling to room temperature, then with 1:1 water, water washing 10min, then in 1000rpm centrifuge under centrifugal 15min, then in 140℃ oven drying 5h, high nickel ternary material drying material into the planetary ball mill, using zirconia ball milling beads, ball ratio control at 1:3. Then, add 5g H3BO3, ball milling at 300rpm for 3h, separate the ball milling beads and ball milling material, put two ingredients into the box, oxygen atmosphere (oxygen concentration ≥ 80%), sintering at 350℃ for 12h. Get the secondary particles of grain with excellent grain strength, can make the battery with good cycle retention rate and excellent gas production performance.

[0086] Comparative example 2.

[0087] First nucleation at high pH value 11.5 and low ammonia value 3.0 g / L, promote its directional growth, the nucleation of the particles into the low pH value 10 and high ammonia value 3.5 g / L environment to grow, improve the disorder degree of particle surface, get internal order external disorder precursor, see example 1 for specific preparation method.

[0088] In 4L high mixer, add 1 kg of precursor Ni 0.83 Co 0.06 Mn 0.11(OH)2, 475 g of lithium hydroxide monohydrate and 3.5 g of MgO were added in a molar ratio of 1 : 1.05 according to the lithiumation coefficient, and mixed at 300 rpm for 120 min. Put into a crucible, and pre-sintered at 600°C for 8 h in an oxygen atmosphere (oxygen concentration ≥ 80%), then heated to 750°C for sintering for 12 h, cooled to room temperature, then washed with water at a ratio of 1:1 for 10 min, then centrifuged at 1000 rpm for 15 min, and then dried in an oven at 140°C for 5 h. The high-nickel ternary material dried material was added into a planetary ball mill, and zirconium oxide grinding beads were used, with a ball-to-material ratio controlled at 1:3. Then, 5 g of H3BO3 was added, and after ball milling at 300 rpm for 3 h, the grinding beads and the grinding material were separated, and the two ingredients were put into a crucible, sintered at 350°C for 12 h in an oxygen atmosphere (oxygen concentration ≥ 80%). The secondary particles of grains with excellent grain strength were obtained, and a battery with good cycle retention rate and excellent gas production performance can be prepared.

[0089] Comparative Example 3.

[0090] First, nucleation was performed at a high pH value of 11.5 and a low ammonia value of 3.0 g / L to promote directional growth, and the nucleated particles were injected into an environment with a low pH value of 10 and a high ammonia value of 3.5 g / L for growth, to increase the disorder degree of the particle surface, to obtain a precursor with an ordered interior and a disordered exterior. The specific preparation method is described in Example 1.

[0091] In a 4L high-speed mixer, 1 kg of the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, 475 g of lithium hydroxide monohydrate and 3.5 g of MgO were added in a molar ratio of 1 : 1.05 according to the lithiumation coefficient, and mixed at 300 rpm for 120 min. Put into a crucible, and pre-sintered at 600°C for 8 h in an oxygen atmosphere (oxygen concentration ≥ 80%), then heated to 750°C for sintering for 12 h, cooled to room temperature, then washed with water at a ratio of 1:1 for 10 min, then centrifuged at 1000 rpm for 15 min, and then dried in an oven at 140°C for 5 h. The high-nickel ternary material dried material was added into a planetary ball mill, and zirconium oxide grinding beads were used, with a ball-to-material ratio controlled at 1:3. Then, 5 g of H3BO3 was added, and after ball milling at 300 rpm for 3 h, the grinding beads and the grinding material were separated, and the two ingredients were put into a crucible, sintered at 350°C for 12 h in an oxygen atmosphere (oxygen concentration ≥ 80%). The secondary particles of grains with excellent grain strength were obtained, and a battery with good cycle retention rate and excellent gas production performance can be prepared.

[0092] Comparative Example 4.

[0093] The precursor is grown at low pH 10 and high ammonia value 3.5 g / L, and a completely disordered precursor is obtained. The precursor prepared by the above method is added into a 4L high-speed mixer at 1 kg, and the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, 475 g of lithium hydroxide monohydrate and 2.5 g of CeO2 are added according to the molar ratio of the lithiumation coefficient 1:1.05, and stirred at 300 rpm for 120 min. Put into the crucible, and oxygen atmosphere (oxygen concentration ≥80%) is introduced, pre-sintered at 600°C for 8h, then heated to 750°C for sintering for 12h, cooled to room temperature, then washed with water at 1:1 for 10 min, then centrifuged at 1000 rpm for 15 min, then dried in an oven at 140°C for 5h, the high-nickel ternary material dried material is added into a planetary ball mill, zirconia grinding beads are used, and the ball-to-material ratio is controlled at 1:3. Then, 5g of H3BO3 is added, and after ball milling at 300 rpm for 3h, the grinding beads and the grinding material are separated, and the two ingredients are put into the crucible, oxygen atmosphere (oxygen concentration ≥80%) is introduced, and sintered at 350°C for 12h. The secondary particles with excellent grain strength are obtained, and the battery with good cycle retention rate and excellent gas production performance can be prepared.

[0094] Comparative Example 5.

[0095] The precursor is grown at high pH 11.5 and low ammonia value 3.0 g / L, and the ordered precursor inside and outside promotes the directional growth. The precursor prepared by the above method is added into a 4L high-speed mixer at 1 kg, and the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, 475 g of lithium hydroxide monohydrate and 2.5 g of CeO2 are added according to the molar ratio of the lithiumation coefficient 1:1.05, and stirred at 300 rpm for 120 min. Put into the crucible, and oxygen atmosphere (oxygen concentration ≥80%) is introduced, pre-sintered at 600°C for 8h, then heated to 750°C for sintering for 12h, cooled to room temperature, then washed with water at 1:1 for 10 min, then centrifuged at 1000 rpm for 15 min, then dried in an oven at 140°C for 5h, the high-nickel ternary material dried material is added into a planetary ball mill, zirconia grinding beads are used, and the ball-to-material ratio is controlled at 1:3. Then, 5g of H3BO3 is added, and after ball milling at 300 rpm for 3h, the grinding beads and the grinding material are separated, and the two ingredients are put into the crucible, oxygen atmosphere (oxygen concentration ≥80%) is introduced, and sintered at 350°C for 12h. The secondary particles with excellent grain strength are obtained, and the battery with good cycle retention rate and excellent gas production performance can be prepared.

[0096] Effect Implementation Example

[0097] The high-nickel positive electrode material obtained in the examples and comparative examples was assembled into a button cell by using a technical solution for preparing a lithium ion battery from a positive electrode material well known to those skilled in the art, in particular as follows: the prepared high-nickel positive electrode material, acetylene black and polyvinylidene fluoride (PVDF) were weighed according to a mass ratio of 94:3:3, mixed uniformly, added with NMP and stirred for 2 h to form a viscous slurry, uniformly coated on an aluminum foil, vacuum baked at 80°C, pressed into a sheet, and cut into a positive electrode sheet with a diameter of 14 mm. A pure lithium sheet with a diameter of 16 mm was used as a negative electrode sheet, a mixed solution of 1 g / L LiPF6+DEC / EC (volume ratio 1:1) was used as an electrolyte, and a poly-Celgard propylene microporous membrane was used as a separator, and the button cell was assembled in an argon-filled glove box.

[0098] Test method:

[0099] Gassing, cycle retention rate and DCR growth rate were tested by full cell

[0100] The full cell was prepared as follows: the high-nickel positive electrode material, conductive carbon black SP, conductive graphite KS-6 and binder PVDF were mixed with NMP to prepare a positive electrode slurry according to a mass ratio of 94.5%:2%:1%:2.5%. The positive electrode slurry was made into a positive electrode sheet through coating and rolling processes, and assembled with a negative electrode (graphite), a separator (poly-Celgard propylene microporous membrane) and an electrolyte (1 mol / L LiPF6+DEC / EC (volume ratio 1:1)) to form a 503048 type full cell with a battery capacity of about 800 mAh.

[0101] The capacity retention rate test was described as follows: a new Wei test cabinet (CT3008-5V3A-A1) was used, the cycle voltage was 4.25-3V at 45°C, the constant voltage cutoff current was 20 mA, and the cycle was 300 times.

[0102] The initial DCR method was as follows: the full cell was cycled at 45°C using a new Wei CT3008-5V3A-A1, the cycle voltage was 4.25-3V, the constant voltage cutoff current was 20 mA, and the cycle was 300 times. At 100% SOC, the voltage V1 was recorded, the discharge current I was set according to 1C, the voltage V2 was recorded after discharging for 30 s, and (V1-V2) / I was calculated to obtain the DCR of each cycle.

[0103] The 7-day 70° gassing performance test was described as follows: the battery was first fully charged, then the battery volume was tested, then the fully charged battery was stored at 70°C for 7 days, then the battery volume was tested again, and the difference between the two was calculated. The volume measuring device was an electronic solid density meter TW-120E.

[0104] The powder resistance method is as follows: using a PD-51 test device, an impedance meter is MCP-T700, using a four-probe method, 4g of the material is weighed and placed in a cylinder with a radius of 10mm, under a pressure of 12MPa, the powder resistance value is recorded.

[0105] The particle strength detection method is as follows: using a Shimadzu DUH-211S device, under a 500 times microscope, a single particle of the dispersed ternary material is found, a 50μm flat head is used to apply pressure, the corresponding pressure and pressure are recorded, and the corresponding pressure of the particle crushing is obtained.

[0106] The test results are shown in Table 1

[0107] Table 1

[0108]

[0109] Table 1 is the capacity, initial efficiency, powder resistance, particle strength, initial DCR, gas production and capacity retention rate data of the high-nickel positive electrode material prepared by the inventive examples 1 / 2 / 3 / 4 and the comparative examples 1 / 2 / 3 / 4 / 5. As shown in Table 1, by introducing the additive containing the ion radius of 80*10 -12 ~120*10 -12 m, the positive electrode material with excellent capacity, powder resistance, particle strength, initial DCR, gas production and capacity retention rate is obtained. The positive electrode prepared by using the completely disordered precursor has low capacity, high powder resistance, and poor initial DCR and capacity retention rate; the positive electrode prepared by using the completely ordered precursor has poor particle strength, gas production and capacity retention rate; the positive electrode material prepared by using the ion doping with small ion radius has poor capacity, particle strength, gas production and capacity retention rate; the positive electrode material prepared by using the ion doping with small ion radius has poor particle strength, gas production and capacity retention rate.

[0110] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, several improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A high-nickel ternary cathode material, characterized in that, The ternary material core comprises high nickel and a coating layer, the structure of the core is whisker arrangement with internal order and outer disorder, the outer layer of the core is further doped with an additive, and the doping elements in the additive are selected from one or more of Y 3+ , Ce 3+ , and Sr 2+ . 2.The high-nickel ternary cathode material of claim 1, characterized in that, The coating layer is lithium borate. 3.The high-nickel ternary cathode material of claim 1, characterized in that, The general formula of the high-nickel ternary material is LiNi x Co y A 1-x-y O2, wherein: 0.6≦x≦1, 0≦y≦0.4, A is at least one element in Mn, Al, Y, Ce, and Sr.

4. The preparation method of the high-nickel ternary positive electrode material according to any one of claims 1-3, characterized in that, The method comprises the following steps: A) mixing a nickel source compound and other metal source compounds, a precipitant and water under a protective atmosphere, then adding a complexing agent, and preliminarily nucleating under the conditions of heating, pH of 11-12 and ammonia value of 2.5-3.2 g / L to obtain a precursor core internal structure with ordered whisker arrangement; Then, adjusting the pH to 9-11 and the ammonia value to 3.2-3.8 g / L to continue nucleating to obtain a precursor with an internal ordered and external disordered whisker arrangement structure; B) mixing the precursor, a lithium source compound and an additive, pre-sintering and then sintering to obtain a ternary positive electrode material core; C) mixing the ternary positive electrode material core with a coating agent and sintering to obtain a high-nickel ternary positive electrode material.

5. The preparation method according to claim 4, characterized in that, The nickel source compound is selected from one or more of nickel sulfate, nickel chloride and nickel nitrate; The other metal source compound is selected from one or more of a cobalt source compound and a manganese source compound; the cobalt source compound is selected from one or more of cobalt sulfate, cobalt chloride and cobalt nitrate; and the manganese source compound is selected from one or more of manganese sulfate, manganese chloride and manganese nitrate; The precipitant is selected from one or more of sodium hydroxide, magnesium hydroxide and potassium hydroxide; The complexing agent is ammonia water.

6. The preparation method according to claim 4, characterized in that, The particle size of the preliminary nucleation is 2-5 μm, and the particle size of the precursor is 9-15 μm.

7. The preparation method according to claim 5, characterized in that, In step B), the lithium source compound is selected from one or more of lithium hydroxide and lithium carbonate; The additive is selected from one or more of CeO2, Y2O3, SrO, CeF3, Y(OH)3, Sr(OH)2 and Ce(OH)4; The sintering has a temperature rising rate of 1-3 ℃ / min, a temperature of 700-850 ℃ and a time of 8-14 h.

8. The preparation method according to claim 5, characterized in that, In step C), the coating agent is selected from one or more of H3BO3, LiBO2, Li2B4O7 and Li3BO3; The sintering has a temperature rising rate of 1-3 ℃ / min, a temperature of 260-360 ℃ and a time of 8-14 h.

9. A lithium-ion battery, characterized by The high-nickel ternary positive electrode material of any one of claims 1-3.

Images