Method for preparing concentration gradient type high-nickel single crystal material by using metal organic framework and high-nickel single crystal material

Abstract

The invention provides a method for preparing a concentration gradient type high-nickel single crystal material by using a metal organic framework and the high-nickel single crystal material.The method comprises the steps that a complexing agent, a precursor stock solution and a precipitator are added into the cobalt-manganese metal organic framework, and a reaction is conducted in the protective atmosphere to prepare a high-nickel material precursor; a lithium source and a metal doping agent are added into the high-nickel material precursor, and the high-nickel material precursor is crushed after being subjected to segmented sintering in an oxygen atmosphere to prepare a concentration gradient type high-nickel single crystal material; wherein the precursor stock solution contains Ni < 2 + >, Co < 2 + > and Mn < 2 + >, and the temperature of the step of segmented sintering is lower than 850 DEG C. The cobalt-manganese metal organic framework is beneficial to preparation of a loose and small-particle-size high-nickel material precursor, cobalt and manganese can be diffused outwards from the core after sintering decomposition, the concentration gradient type high-nickel single crystal material with the high-nickel core and the low-nickel shell can be prepared at low cost, and on the premise that the high capacity of the material is ensured, the high-nickel-content high-nickel single crystal material is obtained. The cycling stability of the material is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a method for preparing a concentration gradient high-nickel single crystal material by utilizing a metal organic framework and the high-nickel single crystal material. Background Art

[0002] High-nickel cathode materials, a next-generation lithium battery cathode material that simultaneously meets the requirements of high capacity and low cobalt, are considered one of the ultimate solutions for high-energy-density lithium-ion batteries. Current commercial high-nickel cathode materials are primarily composed of spherical secondary particle agglomerates formed by randomly arranged primary particles. This structural and compositional characteristic generates significant intra-particle stress during charge-discharge cycles, leading to poor cycling stability.

[0003] The emerging single crystal strategy provides an effective solution to overcome the cycling stability issues of existing high-nickel cathode materials. However, as the Ni content in layered cathode materials continues to increase driven by the electric vehicle market, whether the single crystal strategy can deliver its excellent cycling performance in the extremely challenging ultra-high nickel system (Ni content > 90%) remains to be studied.

[0004] In order to overcome the instability of nickel-rich materials, researchers introduced the design concept of concentration gradient. The Ni content gradually decreases from the core to the outer layer, and the Co and Mn contents gradually increase from the core to the outer layer, showing a certain concentration gradient distribution. The high nickel core provides high capacity, and the low nickel outer layer improves the material's cycle stability.

[0005] Chinese patent publication number CN109962234A discloses a single crystal cathode material with a concentration gradient and a preparation method. This method uses nickel hydroxide particles as a carrier, deposits cobalt salts and manganese salts into the pores of the nickel hydroxide particles, and the prepared precursor is sintered to obtain a single crystal material with a concentration gradient. The nickel hydroxide particles in this method are composed of lamellar primary particles. It is difficult for cobalt salts and manganese salts to deposit into the pores. Even if they can be deposited into the pores, cobalt salts and manganese salts will also be deposited on the surface of the nickel hydroxide particles. During the sintering process, nickel will diffuse into the outer layer of the single crystal particles, which will deteriorate the cycle performance of the single crystal material.

[0006] Chinese patent publication number CN113782736A discloses a gradient single crystal positive electrode material, its preparation method and application. The high Co content on the surface of the single crystal material particles prepared by this method improves the cycle performance of the material, but the added nano-Co(OH)2 increases the preparation cost of the material, and it is prepared through three high-temperature sintering processes, which is complicated and further increases the material cost, making it unfavorable for industrial production. Summary of the Invention

[0007] The object of the present invention is to provide a method for preparing a concentration gradient high nickel single crystal material using a metal organic framework and a high nickel single crystal material, so as to solve the problems in the above background technology.

[0008] The technical solution adopted by the present invention includes: a method for preparing a concentration gradient high nickel single crystal material using a metal organic framework, which comprises the steps of:

[0009] Adding a complexing agent, a precursor solution and a precipitant to a cobalt-manganese metal organic framework, reacting in a protective atmosphere, and preparing a high-nickel material precursor;

[0010] Adding a lithium source and a metal dopant to the high-nickel material precursor, sintering in sections in an oxygen atmosphere, and then crushing the precursor to obtain a concentration gradient high-nickel single crystal material;

[0011] Wherein, the precursor solution contains Ni 2+ 、Co 2+ and Mn 2+ , the temperature of the staged sintering step is less than 850°C.

[0012] Preferably, the cobalt-manganese metal organic framework is cobalt-manganese-based MOF-74, and the ratio of its mass to the total mass of the solute in the precursor solution is (0.05-2):100;

[0013] The molar ratio of Co and Mn in the cobalt-manganese metal organic framework is 1:1 to 1:6; the molar ratio of Ni in the precursor solution is 1:1 to 1:6. 2+ 、Co 2+ and Mn 2+ The total concentration of Ni is 0.5mol / L~2mol / L, 2+ 、Co 2+ and Mn 2+ The molar ratio of =x:y:(1-xy), x≥0.9, y≤0.1, and the particle size of the high-nickel material precursor is 3μm to 5μm.

[0014] Preferably, the pore size of the cobalt-manganese metal organic framework is 1.4 nm to 3.1 nm, and the pore volume is 0.20 cm 3 / g~0.57cm 3 / g, with a specific surface area of ​​736.1m 2 / g~1167.4m 2 / g.

[0015] Preferably, the staged sintering step at least includes:

[0016] The first stage sintering, wherein the ratio of the number of moles of lithium element in the lithium source to the total number of moles of metal elements in the high-nickel material precursor is less than 1;

[0017] The second stage sintering, wherein the ratio of the number of moles of lithium element in the lithium source to the total number of moles of metal elements in the high-nickel material precursor is ≥1;

[0018] The temperature of the first sintering stage is less than the temperature of the second sintering stage.

[0019] Preferably, in the first stage of sintering, the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor is 0.6-0.9, the temperature is 720-780° C., and the time is 6h-14h.

[0020] Preferably, in the second stage of sintering, the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor is 1.0-1.1, the temperature is 800-840° C., and the time is 6 h to 14 h.

[0021] Preferably, the complexing agent includes at least ammonia water, the concentration of which is 3 mol / L to 10 mol / L; the precipitant includes at least sodium hydroxide solution, the concentration of which is 2 mol / L to 8 mol / L; and the protective atmosphere is a nitrogen atmosphere.

[0022] Preferably, the operation of preparing the high-nickel material precursor includes: adding the complexing agent to the cobalt-manganese metal-organic framework, controlling the pH to 11.5-12, controlling the water bath temperature to 45-60°C, introducing nitrogen, stirring at a speed of 400-800 r / min for 30-300 min, and then adding the precursor solution and precipitant.

[0023] Preferably, the metal dopant contains one or more metal elements selected from the group consisting of Al, Zr, Ti, Y, Mg, Sr, Mo, and W, and the metal elements in the metal dopant account for 0.05% to 0.5% of the mass of the high-nickel material precursor.

[0024] The technical solution of the present invention also includes: a high-nickel single crystal material, which is a concentration gradient high-nickel single crystal material, and the single crystal material is prepared using the above-mentioned method of preparing a concentration gradient high-nickel single crystal material using a metal organic framework.

[0025] The beneficial effects of the present invention include at least:

[0026] (1) Cobalt-manganese metal organic framework has a high specific surface area and strong adsorption capacity, which can provide a large number of nucleation sites for the attachment of the precursor solution, which is conducive to the preparation of loose small-particle high-nickel material precursors. Loose small-particle precursors are easier to develop into single crystals, thereby reducing the sintering temperature for preparing single crystals. On the one hand, it reduces production costs, and on the other hand, it reduces the lithium-nickel mixing generated at high temperatures, thereby improving the cycle performance of the prepared concentration gradient high-nickel single crystal material.

[0027] (2) The use of a secondary lithiation process and control of the sintering temperature can effectively reduce the mixing of lithium and nickel and improve the cyclic performance of the material. During sintering, the cobalt-manganese metal organic framework decomposes and carbonizes, and the cobalt and manganese therein diffuse outward from the core along the grain boundaries to obtain a concentration gradient high nickel single crystal material with a high nickel core and a low nickel shell. While ensuring the high capacity of the material, the cyclic stability of the material is effectively improved.

[0028] (3) The preparation method of the present invention is simple, has high scalability, and is easy to promote and apply in industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is an SEM image of the concentration gradient high nickel single crystal material prepared in Example 1 of the present invention;

[0030] Figure 2 It is a statistical graph of the cycle capacity retention rate of the concentration gradient high nickel single crystal materials prepared in Examples 1-6 of the present invention and the high nickel single crystal materials prepared in the comparative example. DETAILED DESCRIPTION

[0031] The embodiments of the present invention are described in detail below.

[0032] The present invention provides a method for preparing a concentration-gradient high-nickel single crystal material using a metal-organic framework, and a high-nickel single crystal material prepared using this method. The high-nickel single crystal material is a concentration-gradient high-nickel single crystal material with a high-nickel core to provide high capacity and a low-nickel shell to improve the material's cyclic stability.

[0033] In this embodiment, the method for preparing a concentration gradient high nickel single crystal material using a metal organic framework comprises the following steps:

[0034] (1) adding a chelating agent, a precursor solution and a precipitant to a cobalt-manganese metal organic framework, reacting in a protective atmosphere to obtain a high-nickel material precursor; wherein the precursor solution contains Ni 2+ 、Co 2+ and Mn 2+ ;

[0035] (2) adding a lithium source and a metal dopant to the high-nickel material precursor, sintering the precursor in stages in an oxygen atmosphere, and then crushing the precursor to obtain a concentration gradient high-nickel single crystal material; wherein the temperature of the staged sintering step is less than 850°C.

[0036] The cobalt-manganese metal-organic framework used in step (1) is a new type of crystalline porous material composed of metal groups and organic linking groups. It has a high specific surface area and strong adsorption capacity, and can provide a large number of nucleation sites for the attachment of the precursor solution, which is conducive to the preparation of loose small-grained high-nickel material precursors. Loose small-grained precursors are easier to develop into single crystals, thereby reducing the sintering temperature for preparing single crystals. On the one hand, it reduces production costs, and on the other hand, it reduces the lithium-nickel mixing generated at high temperatures, thereby improving the cycle performance of the prepared concentration gradient high-nickel single crystal material.

[0037] In some preferred embodiments, the cobalt-manganese metal organic framework used in step (1) is cobalt-manganese-based MOF-74, and the ratio of its mass to the total mass of the solute in the precursor solution is (0.05-2):100; the pore size of the cobalt-manganese metal organic framework is 1.4 nm to 3.1 nm, and the pore volume is 0.20 cm 3 / g~0.57cm 3 / g, with a specific surface area of ​​736.1m 2 / g~1167.4m 2 / g.

[0038] When the high nickel material precursor is prepared by step (1), the molar ratio of Co and Mn in the cobalt manganese metal organic framework is 1:1 to 1:6, and the Ni in the precursor solution is 1:1 to 1:6. 2+ 、Co 2+ and Mn 2+ The total concentration of Ni is 0.5mol / L~2mol / L, 2+ 、Co 2+ and Mn 2+ The molar ratio = x:y:(1-xy), x≥0.9, y≤0.1. During the reaction, the growth state of the high-nickel material precursor is monitored until its particle size reaches 3μm to 5μm.

[0039] In order to obtain a high-nickel material precursor with uniform particle size distribution and good crystallization, the complexing agent in step (1) is ammonia water, and the concentration of ammonia water is 3mol / L to 10mol / L; the precipitant is sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 2mol / L to 8mol / L; the protective atmosphere is nitrogen atmosphere; and the specific operation of step (1) is optimized as follows: adding the complexing agent to the cobalt-manganese metal organic framework, controlling the pH to 11.5 to 12, controlling the water bath temperature to 45 to 60°C, introducing nitrogen as a protective atmosphere, stirring at a speed of 400 to 800 r / min for 30 minutes to 300 minutes to stabilize the reaction environment (including the dispersion uniformity, temperature and pH conditions of the reactants, etc.), and then adding the precursor solution and the precipitant.

[0040] In the reaction of step (1), ammonia is used as a complexing agent to react with transition metal ions (Ni2+ 、Co 2+ and Mn 2+ etc.) to form stable soluble complexes (such as [Ni(NH3)6] 2+ ), slowing down the release rate of transition metal ions and making them react with OH released by the precipitant - The co-precipitation reaction is more uniform and controllable, and at the same time, rapid precipitation caused by local oversaturation is avoided through complex competition balance; the use of sodium hydroxide solution as the precipitant can also maintain a high pH environment (usually ≥11), so that the transition metal ions are completely precipitated and the residue is avoided to cause the components to deviate from the designed ratio.

[0041] In the reaction of step (1), after the precursor solution and the precipitant are added, the transition metal ions and the hydroxide ions undergo a coprecipitation reaction, and the generated nickel, cobalt, and manganese hydroxides grow uniformly outward with the cobalt-manganese metal organic framework as the core, so that the material gradually grows. When the particle size reaches the designed value, the reaction slurry is filtered, washed, and dried to obtain a high-nickel material precursor.

[0042] The above Ni 2+ 、Co 2+ and Mn 2+ They are provided by salt solutions of corresponding transition metal ions, and their specific materials are not limited. As an example, in this embodiment, Ni 2+ Provided by nickel sulfate, Co 2+ Provided by cobalt sulfate, Mn 2+ Provided by manganese sulfate.

[0043] In step (2), the staged sintering step includes a first stage sintering and a second stage sintering. During the first stage sintering, the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor is controlled to be less than 1. During the second stage sintering, the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor is controlled to be ≥1. The temperature of the first stage sintering is controlled to be less than the temperature of the second stage sintering.

[0044] Step (2) uses a secondary lithiation process and controls the sintering temperature, which can effectively reduce lithium-nickel mixing and improve the material's cycle performance. In addition, during the first sintering stage, the cobalt-manganese metal organic framework decomposes and carbonizes, and the cobalt and manganese therein diffuse outward from the core along the grain boundaries, thereby modifying the material and increasing the cobalt and manganese content on the surface of the material, thereby obtaining a single-fired material with a concentration gradient; during the second sintering stage, the material morphology develops from the secondary spheres of the single-fired material into a single crystal, further promoting the outward diffusion of cobalt and manganese elements at the grain boundaries, and the concentration gradient morphology inside the single crystal is also more continuous, thereby obtaining a concentration gradient-type high-nickel single crystal material with a high-nickel core and a low-nickel shell.

[0045] In some preferred embodiments, during the first sintering stage: the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor is 0.6~0.9, the temperature is 720~780℃, and the time is 6h~14h; during the second sintering stage: the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor is 1.0~1.1, the temperature is 800~840℃, and the time is 6h~14h.

[0046] The metal dopant in step (2) can be selected according to the performance requirements. The metal dopant contains one or more metal elements of Al, Zr, Ti, Y, Mg, Sr, Mo, and W. The metal elements in the metal dopant account for 0.05% to 0.5% of the mass of the high-nickel material precursor to improve the comprehensive performance of the concentration gradient high-nickel single crystal material.

[0047] The present invention is further described below through examples and comparative examples. Unless otherwise specified, the raw materials, reagents, or devices used in the examples and comparative examples can be obtained from conventional commercial sources.

[0048] Example 1: Preparation of concentration gradient high nickel single crystal material using metal organic framework

[0049] (1) Prepare 5 mol / L ammonia water as a complexing agent;

[0050] Prepare a 4 mol / L sodium hydroxide solution as a precipitant;

[0051] Weigh nickel sulfate, cobalt sulfate and manganese sulfate, the molar number of Ni in nickel sulfate: the molar number of Co in cobalt sulfate: the molar number of Mn in manganese sulfate = 92:5:3, and mix the weighed nickel sulfate, cobalt sulfate and manganese sulfate to make Ni 2+ 、Co 2+ and Mn 2+ The total concentration of the precursor solution is 1 mol / L;

[0052] The cobalt-manganese metal-organic framework is weighed according to a ratio of the mass of the cobalt-manganese metal-organic framework to the total mass of the solute in the precursor solution of 1:100. The molar ratio of Co and Mn in the cobalt-manganese metal-organic framework is 1:2.

[0053] (2) The cobalt-manganese metal-organic framework was added to the deionized water pre-added in the reactor, and ammonia was pumped into the reactor to control the pH of the reaction liquid to 11.7. The stirring speed of the reactor was adjusted to 600 r / min, the water bath temperature was adjusted to 50°C, and nitrogen was introduced as a protective atmosphere.

[0054] (3) After step (2) is carried out for 30 minutes, the reaction environment in the reactor is stable, and the precursor solution and sodium hydroxide solution are pumped into the reactor; the reaction state is monitored, and after the material particle size reaches 3 μm, the reaction slurry is filtered, washed, and dried to obtain a high-nickel material precursor.

[0055] (4) Weigh 500 g of a high-nickel material precursor and 200.1 g of lithium hydroxide (lithium source), wherein the ratio of the number of moles of lithium element in the lithium source to the total number of moles of metal elements in the high-nickel material precursor is 0.9;

[0056] Weigh 0.3% of the mass of the high nickel material precursor ZrO2 as a metal dopant.

[0057] (5) The high nickel material precursor, lithium hydroxide and ZrO2 are added to a high-speed mixer and fully mixed, and then the first stage of high-temperature solid phase sintering is carried out in an oxygen atmosphere at a sintering temperature of 770°C and a sintering time of 12 hours to obtain a fired material.

[0058] (6) Weigh 500 g of the calcined material and 39.6 g of lithium hydroxide (lithium source), increase the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor to 1.05, add the two into a high-speed mixer and mix them thoroughly, and then carry out the second stage of high-temperature solid-phase sintering in an oxygen atmosphere at a sintering temperature of 820 ° C and a sintering time of 12 h;

[0059] The product of the second stage of high temperature solid phase sintering is crushed into a concentration gradient high nickel single crystal material with a particle size of about 3 μm through jaw crushing, roller crushing, air flow crushing and other processes. The SEM image is shown in the attached Figure 1 .

[0060] Example 2: Preparation of concentration gradient high nickel single crystal material using metal organic framework

[0061] The only difference compared with Example 1 is that the molar ratio of Co to Mn in the cobalt-manganese metal-organic framework in Example 2 is 1:1.

[0062] Example 3: Preparation of concentration gradient high nickel single crystal material using metal organic framework

[0063] The only difference compared with Example 1 is that the molar ratio of Co to Mn in the cobalt-manganese metal-organic framework in Example 3 is 1:6.

[0064] Example 4: Preparation of concentration gradient high nickel single crystal material using metal organic framework

[0065] (1) Prepare 5 mol / L ammonia water as a complexing agent;

[0066] Prepare a 4 mol / L sodium hydroxide solution as a precipitant;

[0067] Weigh nickel sulfate, cobalt sulfate and manganese sulfate, the molar number of Ni in nickel sulfate: the molar number of Co in cobalt sulfate: the molar number of Mn in manganese sulfate = 92:5:3, and mix the weighed nickel sulfate, cobalt sulfate and manganese sulfate to make Ni 2+ 、Co 2+ and Mn 2+ The total concentration of the precursor solution is 1 mol / L;

[0068] The cobalt-manganese metal-organic framework was weighed according to a ratio of the mass of the cobalt-manganese metal-organic framework to the total mass of the solute in the precursor solution of 0.5:100. The molar ratio of Co and Mn in the cobalt-manganese metal-organic framework was 1:2.

[0069] (2) The cobalt-manganese metal-organic framework was added to the deionized water pre-added in the reactor, and ammonia was pumped into the reactor to control the pH of the reaction liquid to 11.7. The stirring speed of the reactor was adjusted to 600 r / min, the water bath temperature was adjusted to 50°C, and nitrogen was introduced as a protective atmosphere.

[0070] (3) After step (2) is carried out for 30 minutes, the reaction environment in the reactor is stable, and the precursor solution and sodium hydroxide solution are pumped into the reactor; the reaction state is monitored, and after the material particle size reaches 3 μm, the reaction slurry is filtered, washed, and dried to obtain a high-nickel material precursor.

[0071] (4) Weigh 500 g of a high-nickel material precursor and 200.1 g of lithium hydroxide (lithium source), wherein the ratio of the number of moles of lithium element in the lithium source to the total number of moles of metal elements in the high-nickel material precursor is 0.9;

[0072] Sb2O5 accounting for 0.2% of the mass of the high-nickel material precursor and TiO2 accounting for 0.1% of the mass of the high-nickel material precursor were weighed as metal dopants.

[0073] (5) The high nickel material precursor, lithium hydroxide, Sb2O5 and TiO2 are added to a high-speed mixer and fully mixed, and then the first stage of high-temperature solid phase sintering is carried out in an oxygen atmosphere at a sintering temperature of 780°C and a sintering time of 12 hours to obtain a fired material.

[0074] (6) Weigh 500 g of the calcined material and 39.6 g of lithium hydroxide (lithium source), increase the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor to 1.1, add the two into a high-speed mixer and mix them thoroughly, and then carry out the second stage of high-temperature solid-phase sintering in an oxygen atmosphere at a sintering temperature of 820 ° C and a sintering time of 12 h;

[0075] The product of the second stage of high-temperature solid-phase sintering is crushed into a concentration gradient high-nickel single crystal material with a particle size of about 3 μm through jaw crushing, roller crushing, air flow crushing and other processes.

[0076] Example 5: Preparation of concentration gradient high nickel single crystal material using metal organic framework

[0077] The only difference compared with Example 4 is that in step (4) of Example 5, the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor is 0.6, and the mass of lithium hydroxide is 133.4 g; in step (6), the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor is 1.1, and the mass of lithium hydroxide is 106.7 g.

[0078] Example 6: Preparation of concentration gradient high nickel single crystal material using metal organic framework

[0079] The only difference compared with Example 4 is that the second high-temperature solid-phase sintering temperature in step (6) of Example 6 is 840°C.

[0080] Comparative Example 1: Preparation of high nickel single crystal material using high nickel precursor prepared by conventional coprecipitation method

[0081] (1) Weigh 500 g of the component prepared by conventional coprecipitation method (i.e., except that no cobalt-manganese metal organic framework is added, the other steps are the same as those in Example 1) 0.92 Co 0.05 Mn 0.03 (OH)2 high nickel precursor;

[0082] Weigh 240.1 g of lithium hydroxide so that the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high nickel precursor is 1.08;

[0083] ZrO2 accounting for 0.2% of the mass of the high nickel precursor was weighed as a metal dopant.

[0084] (2) The high nickel precursor, lithium hydroxide and ZrO2 are added to a high-speed mixer and mixed thoroughly, and then high-temperature solid-phase sintering is carried out in an oxygen atmosphere at a sintering temperature of 820°C and a sintering time of 12 hours. The product of high-temperature solid-phase sintering is crushed into a high nickel single crystal material with a particle size of about 3 μm by jaw crushing, roller crushing, air flow crushing and other processes.

[0085] Battery assembly and performance testing:

[0086] The concentration gradient high nickel single crystal materials prepared in Examples 1-6 and the high nickel single crystal material prepared in Comparative Example 1 were screened, sampled, and assembled and tested for batteries:

[0087] The concentration gradient single crystal material was uniformly mixed with conductive carbon black and adhesive PVDF in a mass ratio of 90:5:5. An appropriate amount of nitrogen-methyl pyrrolidone was added and mixed on a magnetic stirrer for 2 hours. The slurry was evenly coated on aluminum foil using a small coating machine, dried, and pressed into a sheet to form a positive electrode sheet. A metal lithium sheet was used as the negative electrode and assembled into a CR2430 button battery.

[0088] The electrical performance test was carried out using the Xinwei test system. The test conditions were: charge and discharge voltage 3-4.3V, temperature 25°C. The test results are shown in Table 1 and the attached Figure 2 .

[0089] Table 1 Performance test results

[0090]

[0091] From Table 1 and Appendix Figure 2 It is known that compared with the high nickel single crystal prepared by the traditional method in comparative example 1, the concentration gradient type high nickel single crystal materials prepared by metal organic framework in Examples 1-6 have significantly improved cycle capacity retention rates, among which the concentration gradient type high nickel single crystal material prepared in Example 1 has the best comprehensive performance.

[0092] It should be understood that the above-described specific embodiments of the present invention are merely illustrative or illustrative of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the scope of protection of the present invention. In addition, the appended claims are intended to cover all variations and modifications that fall within the scope and metes and bounds of the claims, or equivalents thereof.

Claims

1. A method for preparing a concentration gradient high nickel single crystal material using a metal organic framework, characterized in that: Including steps: Adding a complexing agent, a precursor solution and a precipitant to a cobalt-manganese metal organic framework, reacting in a protective atmosphere, and preparing a high-nickel material precursor; Adding a lithium source and a metal dopant to the high-nickel material precursor, sintering in sections in an oxygen atmosphere, and then crushing the precursor to obtain a concentration gradient high-nickel single crystal material; Wherein, the precursor solution contains Ni 2+ 、Co 2+ and Mn 2+ , the temperature of the staged sintering step is less than 850°C.

2. The method for preparing a concentration gradient high nickel single crystal material using a metal organic framework according to claim 1, characterized in that: The cobalt-manganese metal organic framework is a cobalt-manganese-based MOF-74, and the ratio of its mass to the total mass of the solute in the precursor solution is (0.05-2):100; The molar ratio of Co to Mn in the cobalt-manganese metal-organic framework is 1:1 to 1:6; Ni in the precursor solution 2+ 、Co 2+ and Mn 2+ The total concentration of Ni is 0.5mol / L~2mol / L, 2+ 、Co 2+ and Mn 2+ The molar ratio of =x:y:(1-xy), x≥0.9, y≤0.1, and the particle size of the high-nickel material precursor is 3μm to 5μm.

3. The method for preparing a concentration gradient high nickel single crystal material using a metal organic framework according to claim 1 or 2, characterized in that: The pore size of the cobalt-manganese metal organic framework is 1.4 nm to 3.1 nm, and the pore volume is 0.20 cm 3 / g~0.57cm 3 / g, with a specific surface area of ​​736.1m 2 / g~1167.4m 2 / g.

4. The method for preparing a concentration gradient high nickel single crystal material using a metal organic framework according to claim 3, characterized in that: The staged sintering step at least includes: The first stage sintering, wherein the ratio of the number of moles of lithium element in the lithium source to the total number of moles of metal elements in the high-nickel material precursor is less than 1; The second stage sintering, wherein the ratio of the number of moles of lithium element in the lithium source to the total number of moles of metal elements in the high-nickel material precursor is ≥1; The temperature of the first sintering stage is less than the temperature of the second sintering stage.

5. The method for preparing a concentration gradient high nickel single crystal material using a metal organic framework according to claim 4, characterized in that: In the first stage of sintering, the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor is 0.6-0.9, the temperature is 720-780° C., and the time is 6h-14h.

6. The method for preparing a concentration gradient high nickel single crystal material using a metal organic framework according to claim 4, characterized in that: In the second stage of sintering, the ratio of the molar number of lithium element in the lithium source to the total molar number of metal elements in the high-nickel material precursor is 1.0-1.1, the temperature is 800-840° C., and the time is 6 h to 14 h.

7. The method for preparing a concentration gradient high nickel single crystal material using a metal organic framework according to any one of claims 1-2 and 4-6, characterized in that: The complexing agent at least includes ammonia water, and the concentration of the ammonia water is 3mol / L to 10mol / L; the precipitant at least includes sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 2mol / L to 8mol / L; and the protective atmosphere is nitrogen atmosphere.

8. The method for preparing a concentration gradient high nickel single crystal material using a metal organic framework according to claim 7, characterized in that: The operation of preparing the high-nickel material precursor includes: adding the complexing agent to the cobalt-manganese metal organic framework, controlling the pH to 11.5-12, controlling the water bath temperature to 45-60°C, introducing nitrogen, stirring at a speed of 400-800 r / min for 30-300 min, and then adding the precursor solution and the precipitant.

9. The method for preparing a concentration gradient high nickel single crystal material using a metal organic framework according to any one of claims 1-2, 4-6, and 8, characterized in that: The metal dopant contains one or more metal elements selected from the group consisting of Al, Zr, Ti, Y, Mg, Sr, Mo, and W, and the metal elements in the metal dopant account for 0.05% to 0.5% of the mass of the high-nickel material precursor.

10. A high nickel single crystal material, characterized in that: The high-nickel single crystal material is a concentration gradient high-nickel single crystal material, and the single crystal material is prepared by the method for preparing a concentration gradient high-nickel single crystal material using a metal organic framework as described in any one of claims 1 to 9.

Images