High-dispersion single-crystal high-nickel positive electrode material and preparation method thereof
The precursor composition and conditions were adjusted by the hydroxide co-precipitation method to prepare a high-dispersed single crystal high-nickel positive electrode material, which solved the capacity attenuation problem caused by strain accumulation in the circulation process of the high-nickel positive electrode material in the prior art, achieved the high energy density and cycle stability of the material, and simplified the preparation process.
Patent Information
- Application Number
- CN202510169759.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-17
- Publication Date
- 2025-05-16
AI Technical Summary
The existing high-nickel positive electrode materials have inter-crystal/intra-crystal cracks due to strain accumulation during the cycle, resulting in capacity attenuation, and the single crystal synthesis is difficult, making preparation difficult, affecting large-scale production.
The hydroxide co-precipitation method is used to prepare a high-dispersed single crystal high-nickel positive electrode material by adjusting the chemical composition and preparation conditions of the precursor, which reduces the preparation difficulty and improves the cyclic stability and discharge specific capacity of the material.
The high dispersion of single crystal high-nickel cathode material is achieved, the cation mixing and discharge is reduced, the energy density and cycle stability are improved, the preparation process is simplified, and large-scale production is facilitated.
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Figure CN120004334A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of lithium ion batteries and relates to a highly dispersed single crystal high-nickel positive electrode material and a preparation method thereof. Background Art
[0002] Lithium-ion batteries are widely used in mobile devices, electric vehicles, and grid energy storage due to their high energy density, cost-effectiveness, and long cycle life. The durability of a battery is closely related to its energy density, so improving the energy density of a battery has always been a research hotspot in the field of lithium-ion batteries.
[0003] High nickel cathode materials have the advantages of high energy density and low cost and are strong candidates for future lithium-ion battery cathodes. However, due to the accumulation of anisotropic strain during the charge and discharge process, the generation of intercrystalline / intracrystalline cracks during the cycle process is an important reason for the capacity decay of polycrystalline high nickel cathodes. Single crystalization of high nickel cathodes is generally considered to be one of the ways to solve this problem. However, the contradiction between the loss of Li / O caused by too high synthesis temperature and the inability of single crystal particles to effectively fuse, grow and disperse at too low synthesis temperature is still a major obstacle to the synthesis of single crystal high nickel cathodes. Summary of the invention
[0004] In view of the deficiencies in the prior art, the present invention provides a highly dispersed single crystal high nickel positive electrode material and a preparation method thereof. The single crystal high nickel positive electrode material is obtained by a simple method, which reduces the difficulty of preparing the single crystal high nickel positive electrode material and facilitates the large-scale production of the single crystal high nickel positive electrode material. At the same time, the single crystal high nickel positive electrode material of the present application also has good cycle stability and good discharge specific capacity.
[0005] The method of the present invention is achieved through the following technical solutions:
[0006] A method for preparing a highly dispersed single crystal high nickel positive electrode material, the basic implementation process of which is as follows:
[0007] 1) Preparation of precursor:
[0008] (1) According to the chemical formula [Ni x Co y ](OH)2, wherein 0.8≤x≤0.95, x+y=1, and a metal salt solution is prepared;
[0009] (2) continuously pumping the metal salt solution and ammonia water into the reaction vessel, controlling the alkaline solution feed to adjust the pH to 11.00-11.30, stirring and continuously reacting for a preset time;
[0010] (3) After the reaction is completed, filter, wash and dry to obtain [Ni x Co y ](OH)2 precursor;
[0011] 2) The precursor in step (3) is weighed and mixed with LiOH·H2O, and then ground and calcined to obtain a single crystal positive electrode material.
[0012] Further, in step (1), according to the chemical formula [Ni 0.92 Co 0.08 ](OH)2, NiSO4·6H2O and CoSO4·7H2O were dispersed in deionized water at a molar ratio of Ni:Co=0.92:0.08 to obtain a salt solution.
[0013] Furthermore, in step (2), the concentration of aqueous ammonia is 2.4-4 mol / L.
[0014] Furthermore, in step (2), the concentration of the alkaline solution is 4 mol / L NaOH solution.
[0015] Furthermore, in step (2), aqueous ammonia and a metal salt solution are continuously pumped into the reaction container, respectively, and the reaction temperature is controlled at 50° C.;
[0016] The stirring speed was 700 rpm, and the reaction was continued for 35 h.
[0017] Further, in step (3), after filtering and washing, drying at 80° C. for 12 h to obtain [Ni x Co y ](OH)2 precursor.
[0018] Furthermore, in step 2), the precursor and LiOH·H2O are mixed according to Li:TM=1.03:1.
[0019] Furthermore, in step 2), the calcination is divided into two consecutive calcinations, the first calcination temperature is 480°C, and the second calcination temperature is 730-770°C.
[0020] Furthermore, in step 2), the first calcination time is 5 hours, and the second calcination time is 20 hours.
[0021] On the other hand, the present application also provides a highly dispersed single crystal high nickel positive electrode material prepared by the above method.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] The present invention adopts the most favorable single crystal particle fusion, dispersion precursor and preparation conditions by hydroxide coprecipitation method, and prepares the single crystal high nickel positive electrode material. The whole preparation process is simple and easy to control, and easy to operate, which reduces the difficulty of preparing the single crystal high nickel positive electrode material. At the same time, the precursor of the present application also has smaller primary particles, and the primary particles of the highly exposed crystal plane ({010} crystal plane) and the larger primary particles are accumulated into secondary particles, so that the precursor is in the calcination process, and the smaller primary particles can be conducive to the fusion and dispersion of the particles, and also show lower cation mixing, so that the positive electrode material has higher energy density and cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 XRD patterns of the precursors of Examples 1, 4, and 7 and schematic diagrams of each crystal plane of a primary nanosheet.
[0025] Figure 2 The following are scanning electron microscope images (SEM) of the precursors of Examples 1, 4, and 7.
[0026] Figure 3 This is a scanning electron microscope image (SEM) of the single crystal positive electrode material after lithiation sintering of Example 1-3.
[0027] Figure 4 This is a scanning electron microscope image (SEM) of the single crystal positive electrode material after lithiation sintering of Example 4-6.
[0028] Figure 5 This is a scanning electron microscope image (SEM) of the single crystal positive electrode material after lithiation sintering of Examples 7-9.
[0029] Figure 6 The XRD diagrams of the single crystal positive electrode materials after lithiation sintering of Examples 1, 4, and 7.
[0030] Figure 7 The electrochemical performance diagram of the single crystal positive electrode material after lithiation sintering of Examples 1, 4, and 7. DETAILED DESCRIPTION
[0031] The present invention is further described below in conjunction with embodiments and comparative examples, but the present invention is not limited to the following embodiments and comparative examples.
[0032] This application provides a
[0033] Example 1
[0034] Disperse 2455g of NiSO4·6H2O and 226g of CoSO4·7H2O in deionized water and stir to dissolve. After complete dissolution, add deionized water to make up to 5L and stir evenly to obtain a 2mol / L metal salt solution.
[0035] Dilute 1412 mL of ammonia water with deionized water and make up to 5 L. Stir evenly to obtain a 4 mol / L ammonia solution.
[0036] Disperse 816 g of NaOH in deionized water and stir to dissolve. After the solution is completely dissolved and cooled to room temperature, add deionized water to make up to 5 L. Stir evenly to obtain a 4 mol / L NaOH solution.
[0037] The metal salt solution and ammonia solution were continuously pumped into a 20L stainless steel reactor at a feed rate of 1.7mL / min, and the reaction temperature was controlled at 50°C by a water bath. At the same time, the pH value in the reactor was regulated to 11.30±0.01 by feeding NaOH solution, and the stirring speed was controlled to 700rpm, and the reaction was continued for 35h.
[0038] After the reaction was completed, the reaction product was vacuum filtered, washed, and dried in an oven at 80°C for 12 h to obtain [Ni 0.92 Co 0.08 ](OH)2 precursor.
[0039] Weigh 1 g of the dried precursor and 0.4708 g of LiOH·H2O, grind them thoroughly, and calcine them at 480°C for 5 h in an oxygen atmosphere, and then calcine them at 750°C for 20 h, to finally obtain the single crystal positive electrode material corresponding to Example 1.
[0040] Example 2
[0041] The precursor of Example 1 was mixed with 0.4708 g of LiOH·H2O, ground thoroughly, and calcined at 480°C for 5 h in an oxygen atmosphere, and then calcined at 730°C for 20 h, to finally obtain the single crystal positive electrode material corresponding to Example 2.
[0042] Example 3
[0043] The precursor of Example 1 was mixed with 0.4708 g of LiOH·H2O, ground thoroughly, and calcined at 480°C for 5 h in an oxygen atmosphere, and then calcined at 770°C for 20 h, to finally obtain the single crystal positive electrode material corresponding to Example 3.
[0044] Example 4
[0045] Disperse 2455g of NiSO4·6H2O and 226g of CoSO4·7H2O in deionized water and stir to dissolve. After complete dissolution, add deionized water to make up to 5L and stir evenly to obtain a 2mol / L metal salt solution.
[0046] Dilute 847 mL of ammonia water with deionized water and make up to 5 L. Stir evenly to obtain a 2.4 mol / L ammonia solution.
[0047] Disperse 816 g of NaOH in deionized water and stir to dissolve. After the solution is completely dissolved and cooled to room temperature, add deionized water to make up to 5 L. Stir evenly to obtain a 4 mol / L NaOH solution.
[0048] The metal salt solution and ammonia solution were continuously pumped into a 20L stainless steel reactor at a feed rate of 1.7mL / min, and the reaction temperature was controlled at 50°C by a water bath. At the same time, the pH value in the reactor was regulated to 11.00±0.01 by feeding NaOH solution, and the stirring speed was controlled to 700rpm, and the reaction was continued for 35h.
[0049] After the reaction was completed, the reaction product was vacuum filtered, washed, and dried in an oven at 80°C for 12 h to obtain [Ni 0.92 Co 0.08 ](OH)2 precursor.
[0050] Weigh 1 g of the dried precursor and 0.4708 g of LiOH·H2O, grind them thoroughly, and calcine them at 480°C for 5 h in an oxygen atmosphere, and then calcine them at 750°C for 20 h, to finally obtain the single crystal positive electrode material corresponding to Example 4.
[0051] Example 5
[0052] The precursor of Example 4 was mixed with 0.4708 g of LiOH·H2O, ground thoroughly, and calcined at 480°C for 5 h in an oxygen atmosphere, and then calcined at 730°C for 20 h, to finally obtain the single crystal positive electrode material corresponding to Example 5.
[0053] Example 6
[0054] The precursor of Example 4 was mixed with 0.4708 g of LiOH·H2O, ground thoroughly, and calcined at 480°C for 5 h in an oxygen atmosphere, and then calcined at 770°C for 20 h, to finally obtain the single crystal positive electrode material corresponding to Example 6.
[0055] Example 7
[0056] Disperse 2455g of NiSO4·6H2O and 226g of CoSO4·7H2O in deionized water and stir to dissolve. After complete dissolution, add deionized water to make up to 5L and stir evenly to obtain a 2mol / L metal salt solution.
[0057] Dilute 1130 mL of ammonia water with deionized water and make up to 5 L. Stir evenly to obtain a 3.2 mol / L ammonia solution.
[0058] Disperse 816 g of NaOH in deionized water and stir to dissolve. After the solution is completely dissolved and cooled to room temperature, add deionized water to make up to 5 L. Stir evenly to obtain a 4 mol / L NaOH solution.
[0059] The metal salt solution and ammonia solution were continuously pumped into a 20L stainless steel reactor at a feed rate of 1.7mL / min, and the reaction temperature was controlled at 50°C by a water bath. At the same time, the pH value in the reactor was regulated to 11.20±0.01 by feeding NaOH solution, and the stirring speed was controlled to 700rpm, and the reaction was continued for 35h.
[0060] After the reaction was completed, the reaction product was filtered by vacuum extraction, washed, and dried in an oven at 80°C for 12 h to obtain [Ni 0.92 Co 0.08 ](OH)2 precursor.
[0061] Weigh 1 g of the dried precursor and 0.4708 g of LiOH·H2O, grind them thoroughly, and calcine them at 480°C for 5 h in an oxygen atmosphere, and then calcine them at 750°C for 20 h, to finally obtain the single crystal positive electrode material corresponding to Example 7.
[0062] Example 8
[0063] The precursor of Example 7 was mixed with 0.4708 g of LiOH·H2O, ground thoroughly, and calcined at 480°C for 5 h in an oxygen atmosphere, and then calcined at 730°C for 20 h, to finally obtain the single crystal positive electrode material corresponding to Example 8.
[0064] Example 9
[0065] The precursor of Example 7 was mixed with 0.4708 g of LiOH·H2O, ground thoroughly, and calcined at 480°C for 5 h in an oxygen atmosphere, and then calcined at 770°C for 20 h, to finally obtain the single crystal positive electrode material corresponding to Example 9.
[0066] Effect verification:
[0067] The precursors prepared in Examples 1, 4, and 7 were subjected to crystal structure detection. Figure 1 , Figure 2 Image shown.
[0068] in, Figure 1 The XRD diagram of the precursors of Examples 1, 4, and 7 and the schematic diagram of each crystal plane of the precursor primary particle nanosheets. The precursor samples all showed The β-Ni(OH)2 structure of the space group structure, but specifically, Examples 1, 4, and 7 have different (001) / (100) and (001) / (101) intensity ratios, which means different {010} exposed crystal planes and primary particle morphologies. It shows that different ammonia concentrations and different reaction pH values have an effect on the crystal structure of the precursor. The crystal structure of the precursor can be controlled by adjusting the reaction conditions.
[0069] Figure 2 The SEM images of the precursors of Examples 1, 4, and 7 are shown in Figure 1. It can be seen that the secondary particle sizes of Examples 1, 4, and 7 are all about 2 μm, while the primary particles are quite different. The primary particles of Example 1 are smaller, while those of Example 4 are thicker. Figure 1 The XRD test shows that Example 4 has more {010} crystal plane exposure, which is also completely consistent with Example 7. However, Example 7 presents primary particles of larger size.
[0070] The single crystal positive electrode material, acetylene black and polyvinylidene fluoride (PVDF) prepared in Examples 1, 4 and 7 were made into a slurry in a ratio of 80:13:7 and evenly coated on aluminum foil. After drying in an oven at 120°C for 12 hours, the electrode pieces with a diameter of 14 mm were punched out, which were used as the positive electrode, the lithium sheet was used as the negative electrode, and the electrolyte consisted of 1.0M LiPF6 dissolved in dimethyl carbonate (DMC), diethyl carbonate (DEC) and ethylene carbonate (EC) (volume ratio 1:1:1). The diaphragm was made of PP material (Celgard2500). After being assembled into button cells in a glove box with an argon atmosphere, constant current charge and discharge tests were performed on a Xinwei battery test system (CT3008-W). The voltage range was 2.7-4.3V. The room temperature was kept constant at 30°C.
[0071] The positive electrode materials obtained in Examples 1, 4 and 7 were tested for their effects. Figure 6 , Figure 7 The result graph is shown.
[0072] in, Figure 6 The XRD patterns of relatively dispersed single crystal positive electrode material embodiments 1, 4, and 7 are shown in Table 1. The obvious split peaks of (018) and (110) indicate that the positive electrode materials have a good layered structure. The order of cations can generally be expressed by the ratio of the peak intensities of (003) and (104). (003) / I (104) >1.2, it can be considered that the cations are ordered. From the XRD spectrum, it can be found that the positive electrode material of Example 1 has the largest I (003) / I (104) . This indicates that the positive electrode material of Example 1 has the lowest Li + / Ni 2+ The mixed arrangement indicates that in the single crystal positive electrode material in Example 1, the lithium ions and nickel ions are each in a relatively ideal lattice position, and the regularity of the crystal structure is good. This regular structure is conducive to maintaining the framework stability of the material during the charge and discharge process and reducing the risk of structural distortion caused by ion dislocation.
[0073] Figure 7 The first cycle charge and discharge curves and cycle performance diagrams of the positive electrode materials of the button-type batteries of Examples 1, 4, and 7 are shown in the figure. According to the figure, it can be seen that Example 1 has the highest discharge specific capacity and the best cycle stability, which are 225.77 mAh g -1 , 67.85% capacity retention rate after 100 cycles can be attributed to its highly dispersed single crystal morphology. Due to its structural characteristics, lithium ions can be embedded and extracted more smoothly in the regular structure, and the battery charging and discharging process is more efficient. When charging, lithium ions can be extracted from the positive electrode material more quickly and migrate to the negative electrode; when discharging, lithium ions can smoothly return from the negative electrode to the positive electrode, reducing energy loss and improving charging and discharging efficiency.
[0074] In order to further verify the influence of calcination temperature and positive electrode material, the present application tested the positive electrode material structures of Examples 1-3, 4-6, and 7-9 and obtained the following results.
[0075] Figure 3 The SEM images of the cathode materials of Examples 1-3 are shown. It can be seen that at a relatively low temperature of 730°C, the particles cannot be effectively fused and grown. Due to their high surface energy, the smaller particles become an unstable thermodynamic system. In order to reduce the huge surface energy in the system, the particles are aggregated together through electrostatic attraction and van der Waals forces, which leads to particle agglomeration. The excessively high temperature of 770°C will cause excessive fusion of the particles and cause agglomeration. The appropriate calcination temperature of 750°C can prepare highly dispersed single crystal cathode materials, indicating that smaller primary particles are conducive to the fusion of particles, and highly dispersed single crystal cathode materials can be obtained at a suitable calcination temperature.
[0076] Figure 4 The SEM images of the positive electrode materials of Examples 4 to 6. Both too high and too low calcination temperatures will lead to particle agglomeration, which is the same as the results of Examples 1 and 3, and Example 4 also shows some agglomeration phenomenon, indicating that this type of precursor is not conducive to the fusion and dispersion of particles.
[0077] Figure 5 The SEM images of the positive electrode materials of Examples 7 to 9 are shown in Figure 1. The results of particle agglomeration caused by too high or too low calcination temperatures are the same as above, while Example 7 still exhibits some agglomeration, indicating that this type of precursor is not conducive to the fusion and dispersion of particles.
[0078] In summary, the present invention adopts the most favorable single crystal particle fusion, dispersion precursor and preparation conditions by hydroxide coprecipitation method, and prepares single crystal high nickel positive electrode material. The whole preparation process is simple and easy to control, and easy to operate, which reduces the difficulty of preparing single crystal high nickel positive electrode material. At the same time, the precursor of the present application also has smaller primary particles, and the primary particles of the high exposed crystal plane ({010} crystal plane) and the larger primary particles are accumulated into secondary particles, so that the precursor is in the calcination process, and the smaller primary particles can be conducive to the fusion and dispersion of the particles, and also show lower cation mixing, so that the positive electrode material has higher energy density and cycle stability.
[0079] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.
Claims
1. A method for preparing a highly dispersed single crystal high nickel positive electrode material, characterized in that: The steps include: 1) Preparation of precursor: (1) According to the chemical formula [Ni x Co y ](OH)2, wherein 0.8≤x≤0.95, x+y=1, and a metal salt solution is prepared; (2) continuously pumping the metal salt solution and ammonia water into the reaction vessel, controlling the alkaline solution feed to adjust the pH to 11.00-11.30, stirring and continuously reacting for a preset time; (3) After the reaction is completed, filter, wash and dry to obtain [Ni x Co y ](OH)2 precursor; 2) The precursor in step (3) is weighed and mixed with LiOH·H2O, and then ground and calcined to obtain a single crystal positive electrode material.
2. The preparation method according to claim 1, characterized in that: In step (1), according to the chemical formula [Ni 0.92 Co 0.08 ](OH)2, NiSO4·6H2O and CoSO4·7H2O were dispersed in deionized water at a molar ratio of Ni:Co=0.92:0.08 to obtain a salt solution.
3. The preparation method according to claim 1, characterized in that: In step (2), the concentration of aqueous ammonia is 2.4-4 mol / L.
4. The preparation method according to claim 1, characterized in that: In step (2), the concentration of the alkaline solution is 4 mol / L NaOH solution.
5. The preparation method according to claim 1, characterized in that: In step (2), aqueous ammonia and metal salt solution are continuously pumped into the reaction container, respectively, and the reaction temperature is controlled at 50° C.; The stirring speed was 700 rpm, and the reaction was continued for 35 h.
6. The preparation method according to claim 1, characterized in that: In step (3), after filtering and washing, drying at 80° C. for 12 h, [Ni x Co y ](OH)2 precursor.
7. The preparation method according to claim 1, characterized in that: In step 2), the precursor and LiOH·H2O are mixed according to Li:TM=1.03:
1.
8. The preparation method according to claim 1, characterized in that: In step 2), the calcination is divided into two consecutive calcinations, the first calcination temperature is 480°C, and the second calcination temperature is 730-770°C.
9. The preparation method according to claim 8, characterized in that: In step 2), the first calcination time is 5 h, and the second calcination time is 20 h.
10. A highly dispersed single crystal high nickel positive electrode material, characterized in that: Prepared according to any one of claims 1 to 10.