Doped hydroxyl cobalt oxide and preparation method and application thereof

Abstract

The invention provides doped hydroxyl cobalt oxide and a preparation method and application thereof. Doping elements in the doped hydroxyl cobalt oxide comprise aluminum, magnesium, nickel, manganese and vanadium. According to the preparation method, multiple doped elements such as aluminum, magnesium, nickel, manganese and vanadium are synergistically matched and complemented in valence states, so that multi-electron reaction is realized, lattice distortion is regulated and controlled by ion radius difference, phase change of CoOOH from a beta phase (layered) to an alpha phase (tunnel structure) can be effectively inhibited, a high-activity layered structure is maintained, agglomeration of nano-particles can be effectively inhibited, and the performance of the nano-particles is improved. The specific surface area of the doped hydroxyl cobalt oxide is increased, and continuous exposure of active sites is ensured. Doping elements in the doped hydroxyl cobalt oxide are uniformly doped, the doped hydroxyl cobalt oxide has excellent particle size uniformity and high specific surface area, and the coating performance of the doped hydroxyl cobalt oxide can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials, and in particular relates to a doped cobalt oxyhydroxide and a preparation method and application thereof. Background Art

[0002] Cobalt oxyhydroxide (CoOOH) is widely used as a coating for lithium-ion battery cathode materials due to its high surface area and stable layered structure. However, single-metal doped CoOOH suffers from insufficient electrical conductivity and poor cycling stability. While existing approaches such as aluminum and manganese doping can improve performance, the synergistic effects of multiple metals have yet to be fully exploited.

[0003] Furthermore, doped cobalt oxyhydroxide produced by traditional coprecipitation methods suffers from defects such as uneven doping and wide particle size distribution. For example, patent CN118270854A discloses a method for preparing nanoscale doped cobalt oxyhydroxide and its application. The method comprises the following steps: mixing a soluble salt of a doping element, an oxidant, a cobalt salt solution, a weak base solution, and a strong base solution; the molar ratio of cobalt ions in the oxidant and the cobalt salt solution is 1:(4-25); and the mass molar ratio of cobalt ions in the weak base and the cobalt salt solution is (1.1-2.5):1. Patent CN115849459A discloses a method for preparing cobalt hydroxide and its application. The method comprises mixing a cobalt solution, an alkaline solution, and an additive; the additive comprises ascorbic acid and hydrazine hydrate; the alkaline solution comprises 340-350g and the ascorbic acid comprises 1-2 parts by weight. The cobalt oxyhydroxide synthesized by this method has a low specific surface area, which affects the coating performance.

[0004] Therefore, how to achieve uniform doping of doping elements at the atomic level, improve the particle size uniformity, and at the same time increase the specific surface area of ​​doped cobalt oxyhydroxide and improve the coating performance is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a doped cobalt oxyhydroxide and its preparation method and application. The present invention cooperates with multiple doping elements of aluminum, magnesium, nickel, manganese and vanadium, and realizes multi-electron reaction by valence complementation, and regulates lattice distortion by ionic radius difference, which can effectively inhibit the phase transition of CoOOH from β phase (layered) to α phase (tunnel structure), maintain a highly active layered structure, and can also effectively inhibit the agglomeration of nanoparticles, increase the specific surface area of ​​doped cobalt oxyhydroxide, and ensure continuous exposure of active sites. The doping elements in the doped cobalt oxyhydroxide are uniformly doped, and have excellent particle size uniformity and high specific surface area, which can effectively improve its coating performance.

[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 doped cobalt oxyhydroxide, wherein the doping elements in the doped cobalt oxyhydroxide include aluminum, magnesium, nickel, manganese and vanadium.

[0008] The present invention uses multiple doping elements, including aluminum, magnesium, nickel, manganese, and vanadium, to coordinate and complement valence states to achieve multi-electron reactions and regulate lattice distortion through ionic radius differences. This effectively inhibits the phase transition of CoOOH from the β phase (layered) to the α phase (tunnel structure), maintaining a highly active layered structure. It also effectively inhibits the agglomeration of nanoparticles, increases the specific surface area of ​​the doped cobalt oxyhydroxide, and ensures continuous exposure of active sites. The doped cobalt oxyhydroxide is uniformly doped with doping elements, has excellent particle size uniformity, and a high specific surface area, effectively improving its coating performance.

[0009] In the present invention, aluminum and vanadium have smaller ionic radius than cobalt, so the co-doping of the two will cause lattice contraction, increase lattice stress, promote the generation of oxygen vacancies, and enhance the redox activity of the material; magnesium has a similar radius to cobalt, so its entry into the lattice can reduce lattice distortion and stabilize the layered structure. 2+ -O 2- Ionic bonds can enhance structural stability; the low valence of nickel will produce positive charge defects, promoting electron migration, while the radius of manganese is slightly larger than that of cobalt, which will cause lattice expansion, forming a synergistic effect with the contraction effect of aluminum, which can regulate the interlayer spacing, facilitate ion diffusion, and enhance electrical conductivity. Nickel and manganese can participate in reversible redox reactions, which helps to reduce Co 3+ / Co 4+ The energy barrier of the redox reaction is reduced, and at the same time, the electronic conductivity and the specific capacity of the positive electrode material are improved by forming a Mn-Ni-Co-O mixed valence network. 4+ / V 5+ ) helps to adjust the electrode reaction potential and broaden the operating voltage window. At the same time, it enhances electronic coupling through VO-Co bonds and reduces charge transfer resistance. Although magnesium and aluminum do not directly participate in the electrochemical reaction, they can provide Li + Provides a rapid diffusion channel.

[0010] Preferably, based on the total mass of the doped cobalt oxyhydroxide being 100%, the doping amount of the doping element is 0.05-1.5%, for example, 0.05%, 0.1%, 0.5%, 1% or 1.5%.

[0011] Preferably, in the doped cobalt oxyhydroxide, the mass ratio of aluminum to cobalt is (0.001-0.019):1, for example, it can be 0.001:1, 0.005:1, 0.01:1, 0.012:1, 0.014:1, 0.016:1, 0.018:1 or 0.019:1, etc.

[0012] Preferably, in the doped cobalt oxyhydroxide, the mass ratio of manganese to cobalt is (0.001-0.005):1, for example, it can be 0.001:1, 0.0015:1, 0.002:1, 0.003:1, 0.004:1 or 0.005:1.

[0013] In the present invention, an appropriate content of manganese cooperates with aluminum, magnesium, nickel and vanadium to suppress the Jahn-Teller effect.

[0014] Preferably, in the doped cobalt oxyhydroxide, the mass ratio of magnesium to cobalt is (0.0015-0.006):1, for example, it can be 0.0015:1, 0.002:1, 0.003:1, 0.004:1, 0.005:1 or 0.006:1.

[0015] Preferably, the mass ratio of nickel to cobalt in the doped cobalt oxyhydroxide is (0.0015-0.005):1, for example, it can be 0.0015:1, 0.002:1, 0.003:1, 0.004:1 or 0.005:1.

[0016] Preferably, the mass ratio of magnesium to nickel in the doped cobalt oxyhydroxide is (1-3):1, for example, it can be 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or 3:1.

[0017] In the present invention, the lattice contraction of aluminum and the expansion effect of magnesium complement each other, so the appropriate mass ratio of magnesium and nickel helps to improve the structural stability of doped cobalt oxyhydroxide and enhance the lithium ion transmission rate, thereby improving the specific capacity and rate performance of the positive electrode material.

[0018] Preferably, the mass ratio of vanadium to cobalt in the doped cobalt oxyhydroxide is (0.0005-0.001):1, for example, it can be 0.0005:1, 0.0006:1, 0.0007:1, 0.0008:1, 0.0009:1 or 0.001:1.

[0019] In the present invention, an appropriate vanadium content can be embedded in the CoOOH lattice without destroying the layered structure, and can reduce lattice distortion through charge compensation, thereby assisting in suppressing the Jahn-Teller effect (especially when synergistically combined with manganese). Secondly, the redox pair of vanadium and cobalt can produce a synergistic reaction, increasing the reversible capacity. An appropriate vanadium content can regulate the crystal growth kinetics, inhibit nanoparticle agglomeration, increase the specific surface area, provide a smoother path for ion diffusion, and increase the exposure of active sites.

[0020] In a second aspect, the present invention provides a method for preparing the doped cobalt oxyhydroxide as described in the first aspect, the preparation method comprising the following steps:

[0021] A doping element soluble salt, an oxidant, a cobalt salt solution and a complexing agent are mixed to obtain a mixed salt solution, wherein the doping element soluble salt includes aluminum salt, magnesium salt, nickel salt, manganese salt and vanadium salt.

[0022] The mixed salt solution is added to a bottom liquid through which an oxidizing gas is passed, and a coprecipitation reaction is carried out. After solid-liquid separation, the doped cobalt oxyhydroxide is obtained.

[0023] The present invention adopts a staged oxidation process in the preparation method, which can make each doping ion gradually embedded in the CoOOH lattice according to the thermodynamic order, avoiding element segregation or local agglomeration caused by the difference in precipitation rate; the staged oxidation ensures that Co 3+ Uniform distribution helps to maintain the regularity of the layered structure; segmented oxidation can specifically adjust the valence state of each element, achieve charge balance through multi-valence state combination, enhance interlayer electrostatic interaction, stabilize the structure and improve electronic conduction.

[0024] Preferably, the concentration of cobalt ions in the cobalt salt solution is 100-150 g / L, for example, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L or 150 g / L.

[0025] Preferably, the oxidant comprises hydrogen peroxide.

[0026] Preferably, the mass concentration of the hydrogen peroxide is 5-25%, for example, 5%, 10%, 15%, 20% or 25%.

[0027] Preferably, the mass ratio of the hydrogen peroxide solution to the cobalt metal in the cobalt salt solution is (0.03-0.05):1, for example, it can be 0.03:1, 0.035:1, 0.04:1, 0.045:1 or 0.05:1.

[0028] Preferably, the complexing agent includes a mixture of any two or at least three of ethylenediaminetetraacetic acid disodium salt (EDTA), aminotriacetic acid, diethylenetriaminepentaacetic acid, sodium tripolyphosphate or sodium hexametaphosphate.

[0029] The present invention employs at least two complexing agents in synergistic combination to create a gradient coordination environment, enhancing the stabilization of low-valent ions and inhibiting the formation of impurities such as hydroxide byproducts. The strong complexing agent preferentially coordinates with the high-valent metal ions in the initial reaction phase, forming a stable complex that delays precipitation, while the weak complexing agent releases the metal ions through competitive coordination in the later stages, promoting uniform coprecipitation. This "stabilization followed by release" mechanism improves the uniformity of cobalt oxyhydroxide-doped particles and narrows the particle size distribution.

[0030] Preferably, the mass ratio of the complexing agent to the cobalt metal in the cobalt salt solution is (0.04-0.08):1, for example, it can be 0.04:1, 0.05:1, 0.06:1, 0.07:1 or 0.08:1.

[0031] Preferably, the cobalt salt solution includes any one of a cobalt chloride solution, a cobalt sulfate solution or a cobalt nitrate solution, or a combination of at least two of them.

[0032] Preferably, the anions in the soluble salt of the doping element include any one or a combination of at least two of chloride ions, sulfate ions, or nitrate ions. For example, the aluminum salt may be aluminum chloride, aluminum sulfate, or aluminum nitrate, the magnesium salt may be magnesium chloride, magnesium sulfate, or magnesium nitrate, the nickel salt may be nickel chloride, nickel nitrate, or nickel sulfate, the manganese salt may be manganese chloride, manganese sulfate, or manganese nitrate, and the vanadium salt may be vanadium chloride, vanadium nitrate, or vanadium sulfate.

[0033] Preferably, the oxidizing gas introduced into the base liquid includes air.

[0034] Preferably, the flow rate of the oxidizing gas is 10-15 L / min, for example, it can be 10 L / min, 11 L / min, 12 L / min, 13 L / min, 14 L / min or 15 L / min.

[0035] Preferably, the pH value of the base solution is 10.8-11.5, for example, it can be 10.8, 10.9, 11, 11.1, 11.2, 11.3, 11.4 or 11.5.

[0036] Preferably, the base liquid comprises water and liquid caustic soda. For example, the water may be pure water, and the mass fraction of the liquid caustic soda may be 32%.

[0037] It should be noted that, in the process of the coprecipitation reaction of the present invention, the pH value of the reaction system shows a downward trend, thereby achieving a concentration gradient change of the doping element from the core to the shell of the material particles.

[0038] Preferably, the coprecipitation reaction is accompanied by stirring.

[0039] Preferably, the stirring rate is 400-600 rpm, for example, 400 rpm, 450 rpm, 500 rpm, 550 rpm or 600 rpm.

[0040] Preferably, during the coprecipitation reaction, the feed flow rate of the mixed salt solution is 5-15 L / min, for example, 5 L / min, 7.5 L / min, 10 L / min, 12.5 L / min or 15 L / min, and the feeding time is 2-4 min, for example, 2 min, 2.5 min, 3 min, 3.5 min or 4 min, etc.

[0041] Preferably, the coprecipitation reaction temperature is 60-70°C, for example, 60°C, 65°C or 70°C.

[0042] Preferably, the coprecipitation reaction time is 5-15 min, for example, 5 min, 10 min or 15 min.

[0043] In a third aspect, the present invention provides a positive electrode material for a lithium-ion battery, wherein a coating layer is provided on the surface of the positive electrode material for a lithium-ion battery, and the raw material for preparing the coating layer includes the doped cobalt oxyhydroxide as described in the first aspect.

[0044] When the lithium-ion battery positive electrode material provided by the present invention is in the electrolyte, the aluminum and vanadium in the coating layer can form a stable passivation layer, inhibiting the dissolution of cobalt ions and helping to improve the cycle stability, while magnesium can enhance the mechanical strength of the coating layer and reduce the volume expansion of the battery during charging and discharging.

[0045] In a fourth aspect, the present invention provides a lithium-ion battery, wherein the positive electrode sheet of the lithium-ion battery comprises the lithium-ion battery positive electrode material as described in the third aspect.

[0046] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The present invention uses multiple doping elements, including aluminum, magnesium, nickel, manganese, and vanadium, to coordinate and cooperate with each other, achieve multi-electron reaction through valence complementation, and regulate lattice distortion through ionic radius differences. This can effectively inhibit the phase transition of CoOOH from β phase (layered) to α phase (tunnel structure), maintain a highly active layered structure, and effectively inhibit the agglomeration of nanoparticles, thereby increasing the specific surface area of ​​the doped cobalt oxyhydroxide and ensuring continuous exposure of active sites. The doping elements in the doped cobalt oxyhydroxide are uniformly doped, and the doping has excellent particle size uniformity and high specific surface area, which can effectively improve its coating performance.

[0049] (2) The preparation method provided by the present invention is simple and rapid in reaction, and can achieve uniform atomic-level doping of five elements, namely magnesium, aluminum, manganese, nickel and vanadium, thereby ensuring uniform distribution of the elements in the material, avoiding the occurrence of element aggregation, and maintaining the stability of doping. The synthesized doped hydroxy cobalt oxide has a high specific surface area and can achieve a better coating effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a surface SEM image of the doped cobalt oxyhydroxide prepared in Example 1 of the present invention.

[0051] Figure 2 This is the EDS mapping diagram of the cobalt element in the doped cobalt oxyhydroxide prepared in Example 1 of the present invention.

[0052] Figure 3 EDS Mapping of aluminum element in cobalt oxyhydroxide doped with water prepared in Example 1 of the present invention

[0053] Figure 4 EDS Mapping of nickel in cobalt oxyhydroxide doped with nickel prepared in Example 1 of the present invention

[0054] Figure 5 EDS Mapping of magnesium in cobalt oxyhydroxide doped with magnesium prepared in Example 1 of the present invention

[0055] Figure 6 EDS Mapping of manganese in cobalt oxyhydroxide doped with hydroxyl prepared in Example 1 of the present invention

[0056] Figure 7 This is the EDS mapping diagram of vanadium element in the doped cobalt oxyhydroxide prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0057] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0058] Example 1

[0059] This embodiment provides a doped cobalt oxyhydroxide, wherein the doping elements in the doped cobalt oxyhydroxide include aluminum, magnesium, nickel, manganese, and vanadium.

[0060] Based on the total mass of the doped cobalt oxyhydroxide being 100%, the sum of the doping amounts of aluminum, magnesium and manganese is 0.8%, the doping amount of nickel is 0.4%, the doping amount of vanadium is 0.1%, and the total doping amount is 1.3%.

[0061] In the doped cobalt oxyhydroxide, the mass ratio of aluminum to cobalt is 0.001:1, the mass ratio of manganese to cobalt is 0.003:1, the mass ratio of magnesium to cobalt is 0.004:1, the mass ratio of nickel to cobalt is 0.004:1, the mass ratio of magnesium to nickel is 1:1, and the mass ratio of vanadium to cobalt is 0.001:1.

[0062] This embodiment also provides a method for preparing the doped cobalt oxyhydroxide as described above, the method comprising the following steps:

[0063] (1) Cobalt chloride was used as a raw material to prepare a cobalt chloride solution with a cobalt ion concentration of 130 g / L. Subsequently, aluminum chloride, magnesium chloride, nickel chloride, and manganese chloride were weighed according to the above ratio as doping sources, and hydrogen peroxide with a mass concentration of 5% and a complexing agent were added to mix to obtain a mixed salt solution.

[0064] The mass ratio of hydrogen peroxide to cobalt metal in the cobalt chloride solution is 0.04:1, the complexing agent includes EDTA and aminotriacetic acid in a mass ratio of 1:1, and the mass ratio of the complexing agent to cobalt metal in the cobalt chloride solution is 0.07:1.

[0065] (2) In a 200 L reactor, 100 L of pure water was first added as bottom water, and then liquid alkali with a mass fraction of 32% was added, the pH value of the bottom liquid was adjusted to 11.45, and air was introduced at a flow rate of 10 L / min. The stirring device was turned on and the speed was set to 600 rpm. Then, the mixed salt solution was introduced at a feed flow rate of 10 L / min and the feeding time was 3 min. The coprecipitation reaction was carried out at a temperature of 70° C. for 10 min and then the reaction was terminated. Then, centrifugation, washing, drying and crushing were carried out to obtain the doped cobalt hydroxide oxide.

[0066] Figure 1 The surface SEM image of the doped cobalt oxyhydroxide prepared in this example is shown.

[0067] Figure 2 The EDS mapping diagram of the cobalt element in the doped cobalt oxyhydroxide prepared in this example is shown.

[0068] Figure 3The EDS Mapping diagram of aluminum element in the doped cobalt oxyhydroxide prepared in this embodiment is shown.

[0069] Figure 4 The EDS Mapping diagram of nickel element in the doped cobalt oxyhydroxide prepared in this embodiment is shown.

[0070] Figure 5 The EDS Mapping diagram of magnesium element in the doped cobalt oxyhydroxide prepared in this embodiment is shown.

[0071] Figure 6 The EDS Mapping diagram of manganese element in the doped cobalt oxyhydroxide prepared in this embodiment is shown.

[0072] Figure 7 The EDS mapping diagram of vanadium element in the doped cobalt oxyhydroxide prepared in this example is shown.

[0073] Example 2

[0074] This embodiment provides a doped cobalt oxyhydroxide, wherein the doping elements in the doped cobalt oxyhydroxide include aluminum, magnesium, nickel, manganese, and vanadium.

[0075] Based on the total mass of the doped cobalt oxyhydroxide being 100%, the doping amounts of aluminum, magnesium and manganese are 0.8%, the doping amount of nickel is 0.4%, the doping amount of vanadium is 0.1%, and the total doping amount is 1.3%.

[0076] In the doped cobalt oxyhydroxide, the mass ratio of aluminum to cobalt is 0.002:1, the mass ratio of manganese to cobalt is 0.002:1, the mass ratio of magnesium to cobalt is 0.004:1, the mass ratio of nickel to cobalt is 0.004:1, the mass ratio of magnesium to nickel is 1:1, and the mass ratio of vanadium to cobalt is 0.001:1.

[0077] This embodiment also provides a method for preparing the doped cobalt oxyhydroxide as described above, the method comprising the following steps:

[0078] (1) Cobalt sulfate was used as a raw material to prepare a cobalt sulfate solution with a cobalt ion concentration of 100 g / L. Subsequently, aluminum sulfate, magnesium sulfate, nickel sulfate, and manganese sulfate were weighed according to the above ratio as doping sources, and hydrogen peroxide with a mass concentration of 10% and a complexing agent were added to mix to obtain a mixed salt solution.

[0079] The mass ratio of hydrogen peroxide to cobalt metal in the cobalt sulfate solution is 0.03:1, the complexing agent includes diethylenetriaminepentaacetic acid and aminotriacetic acid in a mass ratio of 1:1, and the mass ratio of the complexing agent to cobalt metal in the cobalt sulfate solution is 0.07:1.

[0080] (2) In a 200 L reactor, 100 L of pure water was first added as bottom water, and then liquid alkali with a mass fraction of 32% was added, the pH value of the bottom liquid was adjusted to 11.45, and air was introduced at a flow rate of 10 L / min. The stirring device was turned on and the speed was set to 500 rpm. Then, the mixed salt solution was introduced at a feed flow rate of 15 L / min and the feed time was 2 min. The coprecipitation reaction was carried out at a temperature of 65° C. for 5 min and then the reaction was terminated. Then, centrifugation, washing, drying and crushing were carried out to obtain the doped cobalt hydroxide oxide.

[0081] Example 3

[0082] This embodiment provides a doped cobalt oxyhydroxide, wherein the doping elements in the doped cobalt oxyhydroxide include aluminum, magnesium, nickel, manganese, and vanadium.

[0083] Based on the total mass of the doped cobalt oxyhydroxide being 100%, the doping amounts of aluminum, magnesium and manganese are 0.8%, the doping amount of nickel is 0.4%, the doping amount of vanadium is 0.1%, and the total doping amount is 1.3%.

[0084] In the doped cobalt oxyhydroxide, the mass ratio of aluminum to cobalt is 0.001:1, the mass ratio of manganese to cobalt is 0.001:1, the mass ratio of magnesium to cobalt is 0.006:1, the mass ratio of nickel to cobalt is 0.004:1, the mass ratio of magnesium to nickel is 1.5:1, and the mass ratio of vanadium to cobalt is 0.001:1.

[0085] This embodiment also provides a method for preparing the doped cobalt oxyhydroxide as described above, the method comprising the following steps:

[0086] (1) Cobalt nitrate was used as a raw material to prepare a cobalt nitrate solution with a cobalt ion concentration of 150 g / L. Subsequently, aluminum nitrate, magnesium nitrate, nickel nitrate, and manganese nitrate were weighed according to the above ratio as doping sources, and hydrogen peroxide with a mass concentration of 15% and a complexing agent were added to obtain a mixed salt solution.

[0087] The mass ratio of hydrogen peroxide to cobalt metal in the cobalt nitrate solution is 0.05:1, the complexing agent includes sodium tripolyphosphate and aminotriacetic acid in a mass ratio of 1:1, and the mass ratio of the complexing agent to cobalt metal in the cobalt nitrate solution is 0.07:1.

[0088] (2) In a 200 L reactor, 100 L of pure water was first added as bottom water, and then liquid alkali with a mass fraction of 32% was added, the pH value of the bottom liquid was adjusted to 11.45, and air was introduced at a flow rate of 10 L / min. The stirring device was turned on and the speed was set to 400 rpm. Then, the mixed salt solution was introduced at a feed flow rate of 5 L / min and the feed time was 4 min. The coprecipitation reaction was carried out at a temperature of 60° C. for 15 min and then the reaction was terminated. Then, centrifugation, washing, drying and crushing were carried out to obtain the doped cobalt hydroxide oxide.

[0089] Example 4

[0090] The difference between this embodiment and embodiment 1 is that the temperature of the coprecipitation reaction in step (2) is 60°C.

[0091] The rest of the preparation methods and parameters remained the same as in Example 1.

[0092] Example 5

[0093] The difference between this embodiment and embodiment 4 is that the coprecipitation reaction time in step (2) is 60 minutes.

[0094] The rest of the preparation methods and parameters remained the same as in Example 4.

[0095] Example 6

[0096] The difference between this embodiment and embodiment 4 is that in the doped cobalt oxyhydroxide, the mass ratio of manganese to cobalt is 0.0007:1, the mass ratio of magnesium to cobalt is 0.0008:1, the mass ratio of nickel to cobalt is 0.0008:1, and the mass ratio of vanadium to cobalt is 0.0001:1.

[0097] The rest of the preparation methods and parameters remained the same as in Example 4.

[0098] Example 7

[0099] The difference between this embodiment and embodiment 4 is that the cobalt chloride solution is replaced by a cobalt sulfate solution of equal concentration.

[0100] The rest of the preparation methods and parameters remained the same as in Example 4.

[0101] Example 8

[0102] The difference between this embodiment and embodiment 1 is that the amount of manganese chloride is adjusted so that the mass ratio of manganese to cobalt in the doped cobalt oxyhydroxide is 0.007:1.

[0103] The rest of the preparation methods and parameters remained the same as in Example 1.

[0104] Example 9

[0105] The difference between this embodiment and embodiment 1 is that the amount of magnesium chloride is adjusted so that the mass ratio of magnesium to nickel in the doped cobalt oxyhydroxide is 0.5:1.

[0106] The rest of the preparation methods and parameters remained the same as in Example 1.

[0107] Example 10

[0108] The difference between this embodiment and embodiment 1 is that the amount of magnesium chloride is adjusted so that the mass ratio of magnesium to nickel in the doped cobalt oxyhydroxide is 3.5:1.

[0109] The rest of the preparation methods and parameters remained the same as in Example 1.

[0110] Example 11

[0111] The difference between this embodiment and embodiment 1 is that the mass ratio of vanadium to cobalt in the doped cobalt oxyhydroxide is 0.0002:1.

[0112] The rest of the preparation methods and parameters remained the same as in Example 1.

[0113] Example 12

[0114] The difference between this embodiment and embodiment 1 is that the mass ratio of vanadium to cobalt in the doped cobalt oxyhydroxide is 0.005:1.

[0115] The rest of the preparation methods and parameters remained the same as in Example 1.

[0116] Example 13

[0117] The difference between this embodiment and embodiment 1 is that the aminotriacetic acid in step (1) is replaced by EDTA of equal mass.

[0118] The rest of the preparation methods and parameters remained the same as in Example 1.

[0119] Example 14

[0120] The difference between this embodiment and embodiment 1 is that the mass concentration of cobalt ions in the cobalt chloride solution in step (1) is 60 g / L.

[0121] The rest of the preparation methods and parameters remained the same as in Example 1.

[0122] Example 15

[0123] The difference between this embodiment and embodiment 1 is that no air is introduced during the reaction.

[0124] The rest of the preparation methods and parameters remained the same as in Example 1.

[0125] Example 16

[0126] The difference between this embodiment and embodiment 1 is that the pH value of the base solution is 12.5.

[0127] The rest of the preparation methods and parameters remained the same as in Example 1.

[0128] Example 17

[0129] The difference between this embodiment and embodiment 1 is that the mass concentration of the hydrogen peroxide in step (1) is 3%.

[0130] The rest of the preparation methods and parameters remained the same as in Example 1.

[0131] Comparative Example 1

[0132] The difference between this comparative example and Example 1 is that the doping element in the doped cobalt oxyhydroxide does not include magnesium.

[0133] The rest of the preparation methods and parameters remained the same as in Example 1.

[0134] Comparative Example 2

[0135] The difference between this comparative example and Example 1 is that the doping element in the doped cobalt oxyhydroxide does not include vanadium.

[0136] The rest of the preparation methods and parameters remained the same as in Example 1.

[0137] Performance Testing

[0138] The doped cobalt oxyhydroxide provided in the above examples and comparative examples was subjected to a specific surface area test and a cobalt content test, wherein the specific surface area was tested by the BET method, and the cobalt content was tested by the ICP-OES method.

[0139] The test results are shown in Table 1.

[0140] Table 1

[0141]

[0142]

[0143] analyze:

[0144] As can be seen from Table 1, the present invention uses multiple doping elements of aluminum, magnesium, nickel, manganese and vanadium to cooperate with each other, achieve multi-electron reaction through valence complementation, and regulate lattice distortion through ionic radius difference. It can effectively inhibit the phase transition of CoOOH from β phase (layered) to α phase (tunnel structure), maintain a highly active layered structure, and effectively inhibit the agglomeration of nanoparticles, increase the specific surface area of ​​doped cobalt oxyhydroxide, and ensure continuous exposure of active sites. The doping elements in the doped cobalt oxyhydroxide are uniformly doped, and have excellent particle size uniformity and high specific surface area, which can effectively improve its coating performance.

[0145] By comparing Example 4 with Example 5, it can be seen that if the coprecipitation reaction time is too long, that is, extended to 60 min, the degree of oxidation is too high. Oxidation for too long will cause CoOOH to form a more tightly stacked layered structure, accompanied by particle aggregation, thereby reducing the specific surface area of ​​doped cobalt oxyhydroxide.

[0146] From the comparison between Example 4 and Example 6, it can be seen that if the amounts of manganese, magnesium, nickel and vanadium in the doped cobalt oxyhydroxide are too small, the highly active layered structure cannot be maintained, resulting in a smaller specific surface area of ​​the doped cobalt oxyhydroxide, which is not conducive to its coating performance.

[0147] From the comparison between Example 1 and Example 8, it can be seen that if the doping amount of manganese in the cobalt oxyhydroxide is too large, it will cause lattice expansion, which is not conducive to ion diffusion.

[0148] By comparing Example 1 with Examples 9-10, it can be seen that if the mass ratio of magnesium and nickel in the doped cobalt hydroxy oxide is too small, the structural stability of the cobalt hydroxy oxide layered structure is reduced; if the mass ratio of magnesium and nickel in the doped cobalt hydroxy oxide is too large, the synergistic balance of the elements will be broken, the degree of lattice distortion will increase, and the crystal structure stability of the cobalt hydroxy oxide will be reduced.

[0149] By comparing Example 1 with Examples 11-12, it can be seen that if the mass ratio of vanadium to cobalt in the doped cobalt oxyhydroxide is too small, the nanoparticles are prone to agglomeration and the specific surface area is reduced; if the mass ratio of vanadium to cobalt in the doped cobalt oxyhydroxide is too large, the layered structure is easily destroyed and the cobalt content is reduced.

[0150] By comparing Example 1 with Example 13, it can be seen that if the aminotriacetic acid in step (1) is replaced by an equal mass of EDTA, that is, only one complexing agent is used, the metal ions are released faster and the cobalt content of the cobalt oxyhydroxide is reduced.

[0151] By comparing Example 1 with Example 14, it can be seen that if the mass concentration of cobalt ions in the cobalt chloride solution in step (1) is reduced to 60 g / L, the amount of liquid alkali is excessive, and a hydrogen-cobalt miscellaneous phase is generated, resulting in a decrease in the cobalt content in the cobalt oxyhydroxide and a significant decrease in the specific surface area of ​​the doped cobalt oxyhydroxide.

[0152] From the comparison between Example 1 and Example 15, it can be seen that if air is not introduced during the reaction process, the degree of oxidation will be insufficient, resulting in a decrease in the cobalt content of the cobalt oxyhydroxide and a significant decrease in the specific surface area of ​​the doped cobalt oxyhydroxide.

[0153] From the comparison between Example 1 and Example 16, it can be seen that if the pH of the base solution is 12.5, an excessive amount of alkali will result in the appearance of a cobalt hydroxide impurity phase, which will reduce the cobalt content of the cobalt oxyhydroxide and significantly reduce the specific surface area.

[0154] By comparing Example 1 with Example 17, it can be seen that if the mass concentration of the hydrogen peroxide in step (1) is too low, such as only 3%, the degree of oxidation will be insufficient, the purity of the cobalt oxyhydroxide will be reduced, the cobalt content of the cobalt oxyhydroxide will be reduced, and the specific surface area will be greatly reduced.

[0155] From the comparison between Example 1 and Comparative Example 1, it can be seen that if the doping element in the doped cobalt oxyhydroxide does not include magnesium, the specific surface area of ​​the cobalt oxyhydroxide will be significantly reduced.

[0156] From the comparison between Example 1 and Comparative Example 2, it can be seen that if the doping element in the doped cobalt oxyhydroxide does not include vanadium, the agglomeration of the nanoparticles will lead to a significant decrease in the specific surface area of ​​the cobalt oxyhydroxide.

[0157] It should be noted that while the present invention illustrates the process method through the above-described embodiments, the present invention is not limited to the above-described process steps, and does not necessarily rely on the above-described process steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent replacements for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A doped cobalt oxyhydroxide, characterized in that: The doping elements in the doped cobalt oxyhydroxide include aluminum, magnesium, nickel, manganese and vanadium.

2. The doped cobalt oxyhydroxide according to claim 1, characterized in that Based on the total mass of the doped cobalt oxyhydroxide as 100%, the doping amount of the doping element is 0.05-1.5%; Preferably, in the doped cobalt oxyhydroxide, the mass ratio of aluminum to cobalt is (0.001-0.019):1; Preferably, in the doped cobalt oxyhydroxide, the mass ratio of manganese to cobalt is (0.001-0.005):1; Preferably, in the doped cobalt oxyhydroxide, the mass ratio of magnesium to cobalt is (0.0015-0.006):1; Preferably, in the doped cobalt oxyhydroxide, the mass ratio of nickel to cobalt is (0.0015-0.005):

1.

3. The doped cobalt oxyhydroxide according to claim 1 or 2, characterized in that In the doped cobalt oxyhydroxide, the mass ratio of magnesium to nickel is (1-3):1; Preferably, in the doped cobalt oxyhydroxide, the mass ratio of vanadium to cobalt is (0.0005-0.001):

1.

4. A method for preparing doped cobalt oxyhydroxide according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: Mixing a soluble salt of a doping element, an oxidant, a cobalt salt solution and a complexing agent to obtain a mixed salt solution; wherein the soluble salt of the doping element includes aluminum salt, magnesium salt, nickel salt, manganese salt and vanadium salt; The mixed salt solution is added to a bottom liquid through which an oxidizing gas is passed, and a coprecipitation reaction is carried out. After solid-liquid separation, the doped cobalt oxyhydroxide is obtained.

5. The preparation method according to claim 4, characterized in that The concentration of cobalt ions in the cobalt salt solution is 100-150 g / L; Preferably, the oxidant comprises hydrogen peroxide; Preferably, the mass concentration of the hydrogen peroxide is 5-25%; Preferably, the mass ratio of the hydrogen peroxide solution to the cobalt metal in the cobalt salt solution is (0.03-0.05):

1.

6. The preparation method according to claim 4 or 5, characterized in that The complexing agent includes any two or a mixture of at least three of ethylenediaminetetraacetic acid disodium salt, aminotriacetic acid, diethylenetriaminepentaacetic acid, sodium tripolyphosphate or sodium hexametaphosphate; Preferably, the mass ratio of the complexing agent to the cobalt metal in the cobalt salt solution is (0.04-0.08):1; Preferably, the cobalt salt solution comprises any one of a cobalt chloride solution, a cobalt sulfate solution or a cobalt nitrate solution, or a combination of at least two thereof; Preferably, the anions in the soluble salt of the doping element include any one of chloride ions, sulfate ions or nitrate ions, or a combination of at least two of them.

7. The preparation method according to any one of claims 4 to 6, characterized in that The oxidizing gas introduced into the base liquid includes air; Preferably, the flow rate of the oxidizing gas is 10-15 L / min; Preferably, the pH value of the base liquid is 10.8-11.

5.

8. The preparation method according to any one of claims 4 to 7, characterized in that The coprecipitation reaction is accompanied by stirring; Preferably, the stirring rate is 400-600 rpm; Preferably, during the coprecipitation reaction, the feed flow rate of the mixed salt solution is 5-15 L / min, and the feeding time is 2-4 min; Preferably, the temperature of the coprecipitation reaction is 60-70°C; Preferably, the coprecipitation reaction time is 5-15 min.

9. A positive electrode material for a lithium ion battery, characterized in that: The surface of the lithium-ion battery positive electrode material is provided with a coating layer, and the raw material for preparing the coating layer includes the doped cobalt oxyhydroxide according to any one of claims 1 to 3.

10. A lithium ion battery, characterized in that: The positive electrode sheet of the lithium-ion battery includes the lithium-ion battery positive electrode material according to claim 9.

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