Precursor material with highly exposed (010) crystal face and preparation method and application thereof

Abstract

The invention provides a precursor material with a highly-exposed (010) crystal face and a preparation method and application thereof.The preparation method comprises the following steps that a mixed metal salt solution, a precipitant solution and a complexing agent solution are introduced into a reaction base solution containing an additive, a nucleation coprecipitation reaction is conducted, seed crystal slurry is obtained, and the seed crystal slurry is prepared; concentrating and washing the seed crystal slurry to obtain seed crystal thick slurry; preparing the seed crystal thick slurry into a seed crystal growth base solution, introducing the mixed metal salt solution, the precipitator solution and the complexing agent solution into the seed crystal growth base solution again, and carrying out growth coprecipitation reaction to obtain the precursor material with the highly exposed (010) crystal face. According to the preparation method, preferred growth of the precursor crystal along the specific crystal face is achieved, the precursor material with the highly-exposed (010) crystal face is obtained, the precursor material has excellent electrochemical performance, the preparation process is simple, cost is low, and large-scale production can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries and relates to a precursor material with a highly exposed (010) crystal plane and a preparation method and application thereof. Background Art

[0002] With the rapid development of portable electronic devices and electric vehicles, the demand for lithium-ion batteries with high energy density, high power density and long cycle stability is growing. The core of lithium-ion batteries is their cathode materials, and high-nickel ternary cathode materials have attracted much attention due to their high specific capacity and low cost. However, high-nickel ternary cathode materials have problems such as structural instability, poor cycle performance and insufficient rate performance during the charge and discharge process, which seriously limit their commercial application.

[0003] In order to solve the above problems, the existing technology has adopted a variety of strategies, including surface coating, ion doping and structural design. Among them, optimizing the microstructure of the positive electrode material by controlling the morphology and crystal orientation of the precursor is an effective strategy. In particular, the high exposure of the (010) crystal plane can provide more channels for the diffusion of lithium ions, thereby improving the rate performance and structural stability of the material. However, the preparation method of the highly exposed (010) crystal plane precursor has problems such as complex process, high cost and poor controllability.

[0004] Therefore, in view of the shortcomings of the prior art, it is necessary to provide a method for preparing a precursor material with a highly exposed (010) crystal plane, which has a simple preparation process, low cost and high controllability. Summary of the invention

[0005] The purpose of the present invention is to provide a precursor material with a highly exposed (010) crystal plane, and a preparation method and application thereof. The preparation method achieves preferential growth of precursor crystals along specific crystal planes by precisely controlling chemical precipitation conditions, thereby obtaining a precursor material with a highly exposed (010) crystal plane. The precursor material not only has excellent electrochemical properties, but also has a simple preparation process, low cost, and can be produced on a large scale.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a precursor material having a highly exposed (010) crystal plane, the preparation method comprising the following steps:

[0008] (1) introducing a mixed metal salt solution, a precipitant solution and a complexing agent solution into a reaction base solution containing additives to perform a nucleation coprecipitation reaction to obtain a seed crystal slurry, and concentrating and washing the seed crystal slurry to obtain a seed crystal concentrated slurry;

[0009] (2) The seed crystal slurry of step (1) is prepared into a seed crystal growth base solution, and a mixed metal salt solution, a precipitant solution and a complexing agent solution are introduced into the seed crystal growth base solution again to perform a growth co-precipitation reaction to obtain the precursor material with a highly exposed (010) crystal face.

[0010] The present invention adopts a reaction base liquid containing additives, and utilizes the additives as crystal plane growth directing agents, so as to form a large number of micronuclei and induce primary grains to grow along the thickness direction, thereby obtaining a precursor seed crystal with a (010) plane being dominant; the seed crystal is then washed and prepared into a reaction base liquid again to continue the growth co-precipitation reaction, and on the basis of the seed crystal, the primary particles of the precursor continue to grow in a stacked manner along the

[001] thickness direction, thereby obtaining a precursor material with a highly exposed (010) crystal plane; in addition, although the present invention adds an additive as a crystal plane growth directing agent in the seed crystal preparation stage, the additive has been precipitated by washing after the seed crystal preparation is completed, and will not have any effect on the quality of the precursor material, which is conducive to improving product quality.

[0011] Since the lattice constant a=b of the hydroxide precursor of nickel, cobalt and manganese, the (010) crystal plane of the present invention refers to the collection of (100) and (010) crystal planes, which reflects the characteristics of the side surfaces of regular hexagonal columnar or blocky crystals.

[0012] Preferably, in the additive-containing reaction base liquid of step (1), the concentration of the additive is 0.05-1.0 mol / L, for example, it can be 0.05 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L or 1 mol / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 0.2-0.4 mol / L.

[0013] The content of the additive in the reaction base solution of the present invention will affect crystal growth, thereby affecting the exposure of the (010) crystal plane. Therefore, the concentration of the additive in the reaction base solution of the present invention is within a specific range, which is conducive to the generation of a precursor material with a highly exposed (010) crystal plane.

[0014] Preferably, the additive in step (1) comprises any one of polyvinyl pyrrolidone, polyethylene glycol, hexadecyltrimethylammonium bromide or triethanolamine, or a combination of at least two thereof.

[0015] The additive of the present invention can be used as a crystal growth directing agent and can also be washed out by soaking in pure water during washing.

[0016] Preferably, the pH of the additive-containing reaction base solution in step (1) is 11.6-12.8, for example, it can be 11.6, 11.8, 12, 12.2, 12.4, 12.6 or 12.8, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 12.0-12.4.

[0017] Preferably, in the additive-containing reaction base liquid of step (1), the concentration of the complexing agent is 0.5-10 g / L, for example, it can be 0.5 g / L, 2 g / L, 4 g / L, 6 g / L, 8 g / L or 10 g / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 3-5 g / L.

[0018] Preferably, the concentration and washing method in step (1) comprises allowing the seed crystal slurry to stand until stratification, extracting the supernatant to achieve concentration, and then adding pure water to soak and wash.

[0019] The invention allows the seed crystal slurry to stand for stratification, then removes the supernatant, adds pure water for immersion and washing, and then removes the supernatant, and repeats the process for several times to finally obtain a seed crystal concentrated slurry free of additives.

[0020] Preferably, the volume ratio of the pure water used for soaking to the concentrated slurry is 2.0-6.0, for example, 2.0, 3.0, 4.0, 5.0 or 6.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, the soaking time is not less than 2 hours, for example, it can be 2 hours, 4 hours, 6 hours, 8 hours or 10 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] Preferably, the number of washings in step (1) is not less than 2 times, for example, it can be 2 times, 3 times, 4 times, 5 times or 6 times, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, in the seed slurry of step (1), the particle size D50 of the seed crystals is 1.0-2.5 μm, for example, it can be 1.0 μm, 1.4 μm, 1.8 μm, 2.2 μm or 2.5 μm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 1.4-2.0 μm.

[0024] The seed particle size D50 obtained in the present invention will affect the growth of particles on the highly exposed (010) crystal plane. If the seed particle size D50 is too small, the proportion of the (010) crystal plane is too small, which is not conducive to the subsequent growth along the (010) crystal plane. If the seed particle size D50 is too large, more additives are wrapped during the particle agglomeration process and are not easy to be removed during the washing process, resulting in more impurities remaining in the precursor particles.

[0025] Preferably, the mixed metal salt solution in step (1) and step (2) comprises any one of a nickel-cobalt-manganese sulfate solution, a nickel-cobalt-manganese nitrate solution or a nickel-cobalt-manganese halide solution, or a combination of at least two thereof.

[0026] Preferably, in the mixed metal salt solution of step (1) and step (2), the total metal ion concentration is 1.0-3.0 mol / L, for example, 1.0 mol / L, 2.0 mol / L or 3.0 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the mass percentage of the precipitant solution in step (1) and step (2) is 20-40%, for example, 20%, 30% or 40%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the mass percentage of the complexing agent solution in step (1) and step (2) is 6-24%, for example, it can be 6%, 10%, 15%, 20% or 24%, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 10-18%.

[0029] Preferably, the temperature of the nucleation co-precipitation reaction in step (1) and the growth co-precipitation reaction in step (2) are both 40-70°C, for example, 40°C, 50°C, 60°C or 70°C, and the rotation speed is both 200-600rpm, for example, 200rpm, 400rpm or 600rpm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, the pH of the nucleation coprecipitation reaction in step (1) is 11.6-12.6, for example, it can be 11.6, 11.8, 12.0, 12.2, 12.4 or 12.6, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, and more preferably 12.0-12.4.

[0031] Preferably, the concentration of the complexing agent in the nucleation coprecipitation reaction in step (1) is 0.5-10 g / L, for example, it can be 0.5 g / L, 2 g / L, 4 g / L, 6 g / L, 8 g / L or 10 g / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 3-5 g / L.

[0032] Preferably, the pH of the growth co-precipitation reaction in step (2) is 9.6-11.2, for example, 9.6, 10, 10.5, 11 or 11.2, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 10.0-10.6.

[0033] Preferably, the concentration of the complexing agent in the growth co-precipitation reaction in step (2) is 2-14 g / L, for example, it can be 2 g / L, 4 g / L, 6 g / L, 8 g / L, 10 g / L, 12 g / L or 14 g / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 5-10 g / L.

[0034] The concentration of the complexing agent in the growth coprecipitation reaction of the present invention is higher than that in the nucleation coprecipitation reaction.

[0035] Preferably, the nucleation co-precipitation reaction in step (1) is carried out in nitrogen and / or argon.

[0036] Preferably, the precipitant solution in step (1) and step (2) is a sodium hydroxide solution.

[0037] Preferably, the complexing agent solution in step (1) and step (2) is aqueous ammonia.

[0038] Preferably, a precipitant, a complexing agent and pure water are added to the seed crystal slurry in step (1) to obtain the seed crystal growth base solution in step (2).

[0039] Preferably, in the seed growth base solution of step (2), the solid content of the seed particles is 5-30wt%, for example, it can be 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] The content of the seed crystals in the seed growth base solution of the present invention will affect the growth of the crystal. If the content of the seed crystal particles is too little, the precursor will grow too fast and cannot grow in a balanced manner according to the preferred crystal plane of the (010) plane; if the content of the seed crystals is too much, the precursor will grow too slowly, affecting the yield and efficiency of the precursor.

[0041] Preferably, the pH of the seed growth base solution in step (2) is 9.6-11.2, for example, 9.6, 10, 10.5, 11 or 11.2, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 10.0-10.6.

[0042] Preferably, the concentration of the complexing agent in the seed growth base solution in step (2) is 2-14 g / L, for example, 2 g / L, 5 g / L, 10 g / L or 14 g / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 5-10 g / L.

[0043] Preferably, the growth co-precipitation reaction in step (2) is carried out to a particle size D50 of 4-18 μm, for example, 4 μm, 8 μm, 12 μm, 16 μm or 18 μm, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 8-12 μm.

[0044] Preferably, after the growth co-precipitation reaction in step (2), the reaction slurry is subjected to alkali washing for more than two times, water washing for more than two times and drying.

[0045] Preferably, the drying temperature is 80-150°C, for example, 80°C, 100°C, 120°C, 140°C or 150°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0046] Preferably, the moisture content of the drying product is below 1.0wt.%, for example, 1.0wt.%, 0.75wt.%, 0.5wt.% or 0.25wt.%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] In a second aspect, the present invention provides a precursor material having a highly exposed (010) crystal plane, wherein the precursor material having a highly exposed (010) crystal plane is prepared using the preparation method described in the first aspect.

[0048] Preferably, the precursor material with highly exposed (010) crystal planes is a spherical secondary particle composed of primary particles.

[0049] Preferably, the peak intensity ratio in the XRD spectrum of the precursor material with a highly exposed (010) crystal plane satisfies I (101) / I (001) >1.25, for example, 1.26, 1.28, 1.3, 1.32, 1.34 or 1.36, 0.75 (010) / I (001) ​<1.25, for example, it can be 0.76, 0.8, 0.9, 1, 1.1 or 1.1, and the crystal plane size satisfies L (010) / L (001) >2.0, for example, it can be 2.1, 2.5, 3.0 or 3.5, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0050] The crystal plane size L of the present invention (010) refers to the crystal plane size of the (010) or (100) plane, and L (001) refers to the crystal plane size of the (001) plane; the calculation of the crystal plane size adopts the Scherrer formula - L = Kλ / βcosθ, where L is the size of the crystal grain on this crystal plane (nm), K is the Scherrer constant, and its value is 0.89, generally taking 1; λ is the X-ray wavelength, and for the Cu target, it is 0.154056 nm; β is the integral half-height width, and during the calculation process, it needs to be converted to radians (rad), and θ is the diffraction angle.

[0051] Preferably, the chemical general formula of the precursor material with a highly exposed (010) crystal plane is Ni x Co y Mn 1-x-y (OH)2, where 0.5 ≤ x ≤ 0.98, for example, it can be 0.5, 0.6, 0.7, 0.8, 0.9 or 0.98, 0 < y ≤ 0.2, for example, it can be 0.05, 0.1, 0.15 or 0.2, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0052] In the third aspect, the present invention provides a lithium-ion battery, and the lithium-ion battery includes a positive electrode material, and the positive electrode material is obtained by mixing and sintering a lithium source and a precursor material with a highly exposed (010) crystal plane as described in the second aspect.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) In the present invention, the precipitation crystallization conditions are controlled and a crystal plane growth guiding agent is added during the crystal seed nucleation stage, a large number of micro-nuclei are formed and the primary crystal grains are induced to grow along the thickness direction, generating precursor crystal seeds with a dominant (010) plane. On the basis of these crystal seeds, the primary particles of the precursor continue to stack and grow along the

[010] thickness direction, and finally a precursor material with a highly exposed (010) crystal plane is obtained;

[0055] (2) Although an organic crystal plane growth guiding agent is added during the crystal seed preparation stage of the present invention, this additive has been washed out by pure water soaking after the crystal seed preparation is completed and will not have any impact on the quality of the precursor, which is beneficial to improving the product quality. Description of the Drawings

[0056] Figure 1 This is the XRD pattern of the precursor material obtained in Example 1 of the present invention;

[0057] Figure 2 This is a SEM image of the precursor material obtained in Example 1 of the present invention;

[0058] Figure 3 This is the XRD pattern of the precursor material obtained in Comparative Example 1 of the present invention;

[0059] Figure 4 This is a SEM image of the precursor material obtained in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0060] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0061] Example 1

[0062] This embodiment provides a method for preparing a precursor material with a highly exposed (010) crystal plane, the preparation method comprising the following steps:

[0063] (1) According to the molecular formula Ni 0.90 Co 0.05 Mn 0.05 (OH)2 (NCM900505) was used to prepare a mixed metal sulfate solution with a total metal ion concentration of 2 mol / L; an ammonia solution with a mass fraction of 16% was prepared; a sodium hydroxide solution with a mass fraction of 30% was prepared; a reaction base solution with a polyethylene glycol concentration of 0.3 mol / L, pH = 12.2 ± 0.1, and an ammonia concentration of 4 ± 0.5 g / L was prepared using a sodium hydroxide solution, polyethylene glycol, concentrated ammonia water, and 20 L of pure water;

[0064] (2) Under the protection of nitrogen atmosphere, the prepared mixed metal sulfate solution, sodium hydroxide solution and ammonia solution were added to the 50L reactor containing the reaction base liquid of step (1) at flow rates of 1.92kg / h, 0.84kg / h and 0.12kg / h, respectively, in a uniform and parallel flow manner to carry out a coprecipitation reaction in the seed preparation stage. During this stage, the pH was controlled at 12.2±0.2, the ammonia concentration was 4±0.5g / L and maintained for 10h, then the feeding was stopped to obtain a primary seed slurry with a seed median particle size of 1.7μm; after the seed slurry was allowed to stand and stratify, the supernatant was removed and the mixture was heated to 400℃. 纯水 / V 浆料 =4 volume ratio, add pure water for soaking and washing, then remove the supernatant, repeat 3 times, and finally obtain a seed slurry with clean additives;

[0065] (3) adding sodium hydroxide solution, concentrated ammonia water and pure water to the seed slurry to prepare a seed growth base solution with a pH of 10.4±0.2, an ammonia concentration of 7±0.5 g / L and a seed solid content of 15%, and then flowing a mixed metal salt solution, a sodium hydroxide solution and ammonia water in parallel at flow rates of 1.92 kg / h, 0.68 kg / h and 0.24 kg / h to carry out a coprecipitation reaction in the precursor growth stage. In this stage, the pH of the system is maintained at 10.3±0.1 and the ammonia concentration is maintained at 7±0.5 g / L. The feeding is stopped after the median particle size D50 reaches 10 μm. After solid-liquid separation, the slurry is washed with dilute sodium hydroxide solution three times and hot pure water three times, and then baked at 100° C. for 16 hours to obtain the precursor material with a highly exposed (010) crystal plane.

[0066] The reaction temperature of the entire coprecipitation reaction of the preparation method is maintained at 58±1°C, and the stirring speed is 400rpm;

[0067] The XRD pattern of the precursor material with highly exposed (010) crystal planes is as follows: Figure 1 As shown, Figure 1 The (100) crystal plane is also the (010) crystal plane, as shown in the SEM image. Figure 2 As shown by Figure 2 It can be seen that the primary grains of the precursor material with a highly exposed (010) crystal plane described in this embodiment are thick and coarse, have obvious layered characteristics, and grow in a stacked manner along the

[010] direction.

[0068] Example 2

[0069] This embodiment provides a method for preparing a precursor material with a highly exposed (010) crystal plane, the preparation method comprising the following steps:

[0070] (1) According to the molecular formula Ni 0.85 Co 0.05 Mn 0.10 (OH)2 was used to prepare a mixed metal sulfate solution with a total metal ion concentration of 1.0 mol / L; an ammonia solution with a mass fraction of 10% was prepared; a sodium hydroxide solution with a mass fraction of 20% was prepared; a reaction base solution with a polyethylene glycol concentration of 0.2 mol / L, pH = 12 ± 0.1, and an ammonia concentration of 3 ± 0.5 g / L was prepared using the sodium hydroxide solution, polyethylene glycol, concentrated ammonia water, and 20 L of pure water;

[0071] (2) Under the protection of nitrogen atmosphere, the prepared mixed metal sulfate solution, sodium hydroxide solution and ammonia solution were added to the 50L reactor containing the reaction base liquid of step (1) at a flow rate of 1.92kg / h, 0.84kg / h and 0.12kg / h respectively in a uniform and parallel flow manner to carry out a coprecipitation reaction in the seed preparation stage. In this stage, the pH was controlled at 12.0±0.1, the ammonia concentration was 3±0.5g / L, and the reaction was carried out until the primary seed slurry with a median particle size of 1.4μm was obtained; after the seed slurry was allowed to stand and stratify, the supernatant was removed and the mixture was heated to 400℃. 纯水 / V 浆料 = 2.0 volume ratio, add pure water for soaking and washing, then remove the supernatant, repeat twice, and finally obtain a seed slurry with clean additives;

[0072] (3) adding sodium hydroxide solution, concentrated ammonia water and pure water to the seed slurry to prepare a seed growth base solution with a pH of 10±0.1, an ammonia concentration of 5.0±0.5 g / L and a seed solid content of 5%, and then flowing a mixed metal salt solution, a sodium hydroxide solution and ammonia water in parallel at flow rates of 1.92 kg / h, 0.68 kg / h and 0.24 kg / h to carry out a coprecipitation reaction in the precursor growth stage. In this stage, the pH of the system is maintained at 10.0±0.1 and the ammonia concentration is 5±0.5 g / L. The feeding is stopped when the median particle size D50 reaches 8 μm. After solid-liquid separation, the slurry is washed with dilute sodium hydroxide solution three times and hot pure water three times, and then baked at 100° C. for 16 hours to obtain the precursor material with a highly exposed (010) crystal plane.

[0073] The reaction temperature of the entire coprecipitation reaction of the preparation method is maintained at 40°C and the stirring speed is 600 rpm;

[0074] Example 3

[0075] This embodiment provides a method for preparing a precursor material with a highly exposed (010) crystal plane, the preparation method comprising the following steps:

[0076] (1) According to the molecular formula Ni 0.90 Co 0.05 Mn 0.05 (OH)2 (NCM900505) was used to prepare a mixed metal sulfate solution with a total metal ion concentration of 3.0 mol / L; an ammonia solution with a mass fraction of 18% was prepared; a sodium hydroxide solution with a mass fraction of 40% was prepared; a reaction base solution with a polyvinyl pyrrolidone concentration of 0.4 mol / L, pH = 12.4 ± 0.1, and an ammonia concentration of 5 ± 0.5 g / L was prepared using sodium hydroxide solution, polyvinyl pyrrolidone, concentrated ammonia water and 20 L of pure water;

[0077] (2) Under the protection of nitrogen atmosphere, the prepared mixed metal sulfate solution, sodium hydroxide solution and ammonia solution were added to the 50L reactor containing the reaction base liquid of step (1) at a flow rate of 1.92kg / h, 0.84kg / h and 0.12kg / h respectively in a uniform and parallel flow manner to carry out the coprecipitation reaction of the seed preparation stage. In this stage, the pH was controlled at pH = 12.4 ± 0.1, the ammonia concentration was 5 ± 0.5g / L, and the reaction was carried out until the primary seed slurry with a median particle size of 2.5μm was obtained; after the seed slurry was allowed to stand and stratify, the supernatant was removed and the mixture was heated to 40°C. 纯水 / V 浆料 = 6.0 volume ratio, add pure water for soaking and washing, then remove the supernatant, repeat 3 times, and finally obtain a seed slurry with clean additives;

[0078] (3) adding sodium hydroxide solution, concentrated ammonia water and pure water to the seed slurry to prepare a seed growth base solution with a pH of 11±0.1, an ammonia concentration of 9.5±0.5 g / L and a seed solid content of 30%, and then flowing a mixed metal salt solution, a sodium hydroxide solution and ammonia water in parallel at flow rates of 1.92 kg / h, 0.68 kg / h and 0.24 kg / h to carry out a coprecipitation reaction in the precursor growth stage. In this stage, the pH of the system is maintained at 10.6±0.1 and the ammonia concentration is maintained at 10±0.5 g / L. The feeding is stopped when the median particle size D50 reaches 12 μm. After solid-liquid separation, the slurry is washed with dilute sodium hydroxide solution three times and hot pure water three times, and then baked at 150° C. for 16 hours to obtain the precursor material with a highly exposed (010) crystal plane.

[0079] The reaction temperature of the entire coprecipitation reaction in the preparation method was maintained at 70° C., and the stirring speed was 200 rpm.

[0080] Example 4

[0081] This embodiment provides a method for preparing a precursor material with a highly exposed (010) crystal plane. The preparation method is the same as that of Example 1 except that the concentration of polyethylene glycol in the reaction base solution in step (1) is 0.05 mol / L.

[0082] Example 5

[0083] This embodiment provides a method for preparing a precursor material with a highly exposed (010) crystal plane. The preparation method is the same as that of Example 1 except that the concentration of polyethylene glycol in the reaction base solution in step (1) is 1 mol / L.

[0084] Example 6

[0085] This embodiment provides a method for preparing a precursor material with a highly exposed (010) crystal plane. The preparation method is the same as that of Embodiment 1 except that the coprecipitation reaction in step (2) is carried out until the median particle size of the seed crystal is 0.8 μm.

[0086] Example 7

[0087] This embodiment provides a method for preparing a precursor material with a highly exposed (010) crystal plane. The preparation method is the same as that of Embodiment 1 except that the coprecipitation reaction in step (2) is carried out until the median particle size of the seed crystal is 3 μm.

[0088] Example 8

[0089] This embodiment provides a method for preparing a precursor material with a highly exposed (010) crystal plane. The preparation method is the same as that of Embodiment 1 except that the solid content of the seed crystal in the seed growth base solution in step (3) is 40%.

[0090] Example 9

[0091] This embodiment provides a method for preparing a precursor material with a highly exposed (010) crystal plane. The preparation method is the same as that of Embodiment 1 except that the solid content of the seed crystal in the seed growth base solution in step (3) is 2%.

[0092] Comparative Example 1

[0093] This comparative example provides a method for preparing a precursor material, which is the same as Example 1 except that in step (2), polyethylene glycol is not added to the reaction base liquid, and the seed slurry is not washed. After the nucleation is completed, the flow rate is adjusted within 3 hours so that the pH of the system is reduced to 10.3±0.1 and the ammonia concentration is increased to 7±0.5 g / L to perform a coprecipitation reaction in the seed growth stage.

[0094] The XRD pattern of the precursor material in this comparative example is as follows Figure 3 As shown in the SEM images Figure 4 shown.

[0095] Comparative Example 2

[0096] This comparative example provides a method for preparing a precursor material. The preparation method is the same as Example 1 except that in step (2), the seed slurry is not washed, and after the nucleation is completed, the flow rate is adjusted within 3 hours to reduce the pH of the system to 10.3±0.1 and the ammonia concentration is increased to 7±0.5 g / L to carry out a co-precipitation reaction in the seed growth stage.

[0097] I of the precursor materials of the above embodiments and comparative examples (101) / I (001) , I(010) / I (001) and L (010) / L (001) As shown in Table 1; the precursor materials obtained in the above examples and comparative examples were uniformly mixed with lithium hydroxide according to a lithium ratio of Li / TM=1.03, sintered at 720°C for 18 hours to obtain positive electrode materials, and assembled into button batteries for electrochemical performance testing. The specific experimental steps are as follows: First, the active material (sintered positive electrode material), conductive agent acetylene black, and binder polyvinylidene fluoride were dissolved in N-methylpyrrolidone at a mass ratio of 8:1:1, and the slurry was mixed using a homogenizer in a multi-stage mode at room temperature; then, the ground slurry was evenly applied to the aluminum foil with a coater, and dried at 80°C in a vacuum drying oven for 12 hours; finally, the aluminum foil was punched into 1.13 cm 2 Circular electrode sheet.

[0098] The obtained electrode sheet was used as the positive electrode, the lithium metal sheet was used as the counter electrode, and the porous polypropylene membrane (Celgard2400, USA) was used as the separator to separate the positive electrode and the counter electrode. The CR-2032 battery was assembled in a glove box filled with Ar gas. The battery was tested using a battery test system (Blue Electric CT2001A, Wuhan, China). First, it was activated three times at 0.1C rate / 2.7~4.3V, and then the activated button cell was tested for electrochemical performance under the conditions of 2.7-4.3V@0.1C / 1C. The test results are shown in Table 1.

[0099] Table 1

[0100]

[0101] From Table 1 we can see that:

[0102] (1) It can be seen from Example 1 and Comparative Example 1 that the primary grain layered characteristics of the precursor material in Comparative Example 1 are not obvious, the stacking growth along the

[001] thickness direction is not obvious, the proportion of exposed side surfaces such as (010) and (100) is small, and the diffraction peak intensity does not meet I (101) / I (001) >1.25,0.75 (010) / I (001) <1.25, the crystal plane size does not meet L (010) / L (001) ​>2.0, the 0.1C first cycle discharge capacity decreased from 223.4mAh / g in Example 1 to 213.4mAh / g, the 1C / 0.1C discharge capacity ratio decreased from 94.2% to 90.3%, and the 1C cycle 100 cycle capacity retention rate decreased from 92.6% to 90.1%; while the SEM morphology and XRD spectrum of the precursor material obtained in Comparative Example 2 were similar to those in Example 1, but it was not washed, the precursor material contained impurities, and the diffraction peak intensity did not meet 0.75 (010) / I (001) <1.25, the 0.1C first cycle discharge capacity decreased from 223.4 mAh / g in Example 1 to 212.2 mAh / g, the 1C / 0.1C discharge capacity ratio decreased from 94.2% to 93.4%, and the capacity retention rate after 100 cycles at 1C decreased from 92.6% to 89.4%.

[0103] (2) It can be seen from Examples 1 and 4-5 that the content of additives in the reaction base solution will affect crystal growth. (010) / L (001) The value is reduced, thereby affecting the exposure of the (010) crystal plane and the electrochemical performance of the battery, causing the battery's 0.1C first cycle discharge capacity, 1C / 0.1C discharge capacity ratio and 1C cycle 100 cycle capacity retention rate to decrease; from Examples 1 and 6-9, it can be seen that the particle size and content of the seed crystals of the present invention will affect the crystal growth, L (010) / L (001) The value decreases, thus affecting the exposure of the (010) crystal plane and the electrochemical performance of the battery, causing the battery's 0.1C first cycle discharge capacity, 1C / 0.1C discharge capacity ratio and 1C cycle 100 cycle capacity retention rate to decrease.

[0104] In summary, the present invention provides a precursor material with a highly exposed (010) crystal plane, and a preparation method and application thereof. The preparation method achieves preferential growth of precursor crystals along specific crystal planes by precisely controlling chemical precipitation conditions, thereby obtaining a precursor material with a highly exposed (010) crystal plane. The precursor material not only has excellent electrochemical properties, but also has a simple preparation process, low cost, and can be mass-produced.

[0105] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.​

Claims

1. A method for preparing a precursor material having a highly exposed (010) crystal plane, characterized in that: The preparation method comprises the following steps: (1) introducing a mixed metal salt solution, a precipitant solution and a complexing agent solution into a reaction base solution containing additives to perform a nucleation coprecipitation reaction to obtain a seed crystal slurry, and concentrating and washing the seed crystal slurry to obtain a seed crystal concentrated slurry; (2) The seed crystal slurry of step (1) is prepared into a seed crystal growth base solution, and a mixed metal salt solution, a precipitant solution and a complexing agent solution are introduced into the seed crystal growth base solution again to perform a growth co-precipitation reaction to obtain the precursor material with a highly exposed (010) crystal face.

2. The preparation method according to claim 1, characterized in that: In the reaction base solution containing additives in step (1), the concentration of the additives is 0.05-1.0 mol / L, preferably 0.2-0.4 mol / L; Preferably, the additive in step (1) comprises any one of polyvinyl pyrrolidone, polyethylene glycol, hexadecyltrimethylammonium bromide or triethanolamine, or a combination of at least two thereof; Preferably, the pH of the additive-containing reaction base solution in step (1) is 11.6-12.8, preferably 12.0-12.4; Preferably, in the additive-containing reaction base solution of step (1), the concentration of the complexing agent is 0.5-10 g / L, preferably 3-5 g / L.

3. The preparation method according to claim 1 or 2, characterized in that: The concentration and washing method of step (1) comprises allowing the seed crystal slurry to stand until stratification, then removing the supernatant to achieve concentration, and then adding pure water to soak for washing; Preferably, the volume ratio of the pure water used for soaking to the concentrated slurry is 2.0-6.0; Preferably, the soaking time is not less than 2 hours; Preferably, the washing is performed no less than 2 times in step (1).

4. The preparation method according to any one of claims 1 to 3, characterized in that In the seed slurry of step (1), the particle size D50 of the seed is 1.0-2.5 μm, preferably 1.4-2.0 μm; Preferably, the mixed metal salt solution in step (1) and step (2) comprises any one of a nickel-cobalt-manganese sulfate solution, a nickel-cobalt-manganese nitrate solution or a nickel-cobalt-manganese halide solution or a combination of at least two thereof; Preferably, in the mixed metal salt solution of step (1) and step (2), the total metal ion concentration is 1.0-3.0 mol / L.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The mass percentage of the precipitant solution in step (1) and step (2) is 20-40%; Preferably, the mass percentage of the complexing agent solution in step (1) and step (2) is 6-24%, preferably 10-18%; Preferably, the temperature of the nucleation co-precipitation reaction in step (1) and the growth co-precipitation reaction in step (2) are both 40-70° C., and the rotation speed is both 200-600 rpm; Preferably, the pH of the nucleation coprecipitation reaction in step (1) is 11.6-12.6, preferably 12.0-12.4; Preferably, the concentration of the complexing agent in the nucleation coprecipitation reaction in step (1) is 0.5-10 g / L, preferably 3-5 g / L; Preferably, the pH of the growth coprecipitation reaction in step (2) is 9.6-11.2, preferably 10.0-10.6; Preferably, the concentration of the complexing agent in the growth co-precipitation reaction in step (2) is 2-14 g / L, preferably 5-10 g / L.

6. The preparation method according to any one of claims 1 to 5, characterized in that: Adding a precipitant, a complexing agent and pure water to the seed crystal slurry of step (1) to obtain the seed crystal growth base solution of step (2); Preferably, in the seed growth base solution of step (2), the solid content of the seed particles is 5-30wt%; Preferably, the pH of the seed growth base solution in step (2) is 9.6-11.2, preferably 10.0-10.6; Preferably, the concentration of the complexing agent in the seed growth base solution in step (2) is 2-14 g / L, preferably 5-10 g / L.

7. The preparation method according to any one of claims 1 to 6, characterized in that: Step (2) the growth coprecipitation reaction is carried out until the particle size D50 is 4-18 μm, preferably 8-12 μm; Preferably, after the growth co-precipitation reaction in step (2), the reaction slurry is subjected to alkali washing for more than two times, water washing for more than two times and drying; Preferably, the drying temperature is 80-150°C.

8. A precursor material having a highly exposed (010) crystal plane, characterized in that: The precursor material with a highly exposed (010) crystal plane is prepared by the preparation method according to any one of claims 1 to 7.

9. The precursor material with a highly exposed (010) crystal plane according to claim 8, characterized in that: The precursor material with highly exposed (010) crystal planes is a spherical secondary particle composed of primary particles; Preferably, the peak intensity ratio in the XRD spectrum of the precursor material with a highly exposed (010) crystal plane satisfies I (101) / I (001) >1.25,0.75 (010) / I (001) <1.25, the crystal plane size meets L (010) / L (001) >2.0;​ Preferably, the chemical formula of the precursor material with a highly exposed (010) crystal plane is Ni x Co y Mn 1-x-y (OH)2, where 0.5≤x≤0.98, 0 <y≤0.2。 10. A lithium ion battery, characterized in that: The lithium-ion battery comprises a positive electrode material, which is obtained by mixing and sintering a lithium source and a precursor material with a highly exposed (010) crystal plane as claimed in claim 8 or 9.

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