Method for regulating high (010) crystal plane exposure of layered oxide positive electrode material

Abstract

The present application belongs to the technical field of lithium ion battery electrode material, and particularly relates to a method for regulating high-exposure (010) crystal plane of layered oxide positive electrode material. The present application introduces aluminum-nitrogen compound and silicon-containing compound modification material into layered oxide positive electrode precursor by solid phase method, and induces the layered oxide material crystal to grow along (010) crystal plane in the subsequent sintering and lithiumation process, so as to finally obtain layered oxide positive electrode material with high-exposure (010) crystal plane. The layered oxide positive electrode material with high-exposure (010) crystal plane has good primary grain uniformity and strong structure stability, not only realizes the improvement of rate performance of layered oxide positive electrode material, but also significantly improves the specific capacity and cycle stability through doping and coating modification of the material. The method is simple in process, strong in universality, low in cost and excellent in performance, and has great industrial production application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery electrode materials, and particularly relates to a method for regulating and controlling the highly exposed (010) crystal plane of a layered oxide positive electrode material. Background Art

[0002] The rapid development of electric vehicles and electric aircraft is placing higher demands on the power density of lithium-ion batteries. Layered oxide cathode materials, with their high discharge capacity and discharge voltage, are currently the preferred materials for high-energy-density lithium-ion batteries. However, the rate performance of layered oxide cathode materials still cannot meet the high-power requirements of lithium-ion batteries.

[0003] In layered oxide materials, the (010) plane along the c-axis has a completely open characteristic, which is the Li + The active crystal plane for insertion and diffusion, the exposed (010) surface can ensure the Li + The intercalation and deintercalation process is smooth. Existing technologies usually achieve this by regulating the morphological structure of the precursor and the doping of the precursor elements. By adjusting the reaction time, reaction pH value, ammonia concentration and other process parameters during the co-precipitation reaction to adjust the precursor morphology, and then using the characteristics of the layered cathode material inherited from the precursor morphology to induce the exposure of the (010) crystal plane, a layered oxide cathode material with a high exposure of the (010) crystal plane can be obtained. In addition, the formation energy of the (010) crystal plane can also be reduced by doping with the precursor elements, promoting the exposure of the (010) crystal plane during the lithiation process.

[0004] However, these technologies are complex and require extremely stringent precursor preparation conditions, making them difficult to implement industrially. For example, Chinese patent publication number CN115849460A discloses a method for regulating the preferential growth of the (010) crystal plane of a ternary material. By doping a layered oxide precursor with tungsten and adjusting the tungsten source addition method and the lithiation sintering method, a tungsten-doped layered oxide cathode material with a high (010) exposed surface is prepared, effectively improving the electrochemical performance of the material. However, the specific tungsten source addition method and lithiation sintering method in this patent are complex, significantly increasing production costs and making them unsuitable for large-scale industrial production.

[0005] Based on this, the present invention adopts a simple solid-phase method. Without changing the original precursor and lithiation sintering process, it only introduces aluminum nitrogen compounds and silicon-containing compound modifying materials into the layered oxide positive electrode precursor. In the subsequent sintering and lithiation process, the modified materials can be used to induce the layered oxide material crystals to grow preferentially along the (010) crystal plane. In addition, while inducing the preferential growth of the (010) crystal plane, the present invention also achieves doping and coating modification of the material, achieving a simultaneous improvement in the rate performance, specific capacity and cycle life of the layered oxide positive electrode material. The preparation method of the present invention is highly versatile and can be applied to layered oxide single crystals and polycrystalline positive electrode materials with various nickel contents. Summary of the Invention

[0006] The purpose of the present invention is to address the problem that the existing technology is difficult to achieve high exposure of (010) crystal planes in layered oxide positive electrode materials at low cost, and to propose a method for regulating the high exposure of (010) crystal planes in layered oxide positive electrode materials. Only a simple solid-phase method is used to introduce a modified material into the precursor and adjust the preparation process parameters. Not only is the rate performance of the layered oxide positive electrode material with high exposure of (010) crystal planes improved, but the material is also doped and coated to significantly improve the specific capacity and cycle stability. The method is simple in process, highly versatile, low in cost, and has outstanding performance, and has great prospects for industrial production and application.

[0007] Furthermore, the present invention also provides the use of the layered oxide positive electrode material with highly exposed (010) crystal planes prepared by the method in the preparation of lithium-ion batteries.

[0008] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0009] A method for preparing a layered oxide positive electrode material with a highly exposed (010) crystal plane comprises the following steps:

[0010] The layered oxide cathode material precursor, lithium source, aluminum nitrogen compound and silicon-containing compound are uniformly mixed in a certain molar ratio, and then placed in an atmosphere furnace for sintering to obtain a layered oxide cathode material with a highly exposed (010) crystal plane.

[0011] Furthermore, the chemical formula of the layered oxide cathode material precursor is Ni 1-x-y-z Co x Mn y Al z (OH)2, x≥0, y≥0, z≥0, 0.3<(1-xyz)≤1.

[0012] More preferably, the chemical formula of the layered oxide cathode material precursor is Ni 0.96 Co 0.015Mn 0.015 Al 0.01 (OH)2、Ni 0.83 Co 0.12 Mn 0.05 (OH)2.

[0013] Furthermore, the lithium source is one or more of lithium hydroxide, lithium carbonate and lithium nitrate.

[0014] Furthermore, the aluminum nitrogen compound is a combination of one or more of dihydroxyamino aluminum acetate, aluminum nitride, and aluminum nitrate.

[0015] Furthermore, the silicon-containing compound is a combination of one or more of silicon dioxide, silicon monoxide, silicon nitride, silicon hexaboride, silicon carbide, lithium silicate, and silicon tetrafluoride.

[0016] Furthermore, the molar ratio of the layered oxide cathode material precursor, lithium source, aluminum nitrogen compound and silicon-containing compound is 1:(0.9-1.6):(0.0001-1):(0.0001-1).

[0017] Furthermore, the atmosphere in the atmosphere furnace is an oxygen atmosphere, a nitrogen atmosphere, an ammonia atmosphere, a sulfur dioxide atmosphere, a hydrogen sulfide atmosphere, or a combination of any two of these five gases.

[0018] Furthermore, the sintering includes one-stage sintering and two-stage sintering; the temperature of the one-stage sintering is 200-650°C; the time of the one-stage sintering is 0.5-24 hours; the temperature of the two-stage sintering is 500-1300°C; the time of the two-stage sintering is 1-72 hours.

[0019] Furthermore, the present invention also provides a layered oxide positive electrode material with a high exposure of (010) crystal planes prepared by the above method, which has good rate performance, specific capacity and cycle stability and can be used to prepare lithium-ion batteries.

[0020] Furthermore, based on a general inventive concept, the present invention also provides the use of the layered oxide positive electrode material with a high exposure of (010) crystal planes in the preparation of lithium-ion batteries.

[0021] Furthermore, the present invention also provides a method for preparing a lithium-ion battery using the layered oxide positive electrode material with a high exposure of the (010) crystal plane, which specifically comprises the following steps:

[0022] a. placing a certain amount of a layered oxide cathode material having a highly exposed (010) crystal plane, a conductive agent, and a binder in a container to obtain a mixed powder;

[0023] b. Add a solvent to the mixed powder in step a, ultrasonically disperse it at a power of 80 to 100 W for 8 to 12 minutes, then place a polytetrafluoroethylene magnet in a container and stir it at a speed of 300 to 400 r / min for 8 to 12 hours to uniformly disperse the layered oxide cathode material with a highly exposed (010) crystal plane and the conductive agent to obtain a mixed slurry;

[0024] c. The mixed slurry in step b is coated on aluminum foil (current collector), dried at 60-80°C for 8-12 hours, and then made into a button-type electrode sheet; then, the prepared electrode sheet is used as the working electrode, the metal lithium sheet is used as the counter electrode, a diaphragm is installed, and the electrolyte is a high-nickel 4.3V electrolyte. A button battery is assembled, and the battery model is a CR2032 button battery.

[0025] Specifically, in step a, the conductive agent is carbon black (Super-P); and the binder is PVDF.

[0026] Specifically, the solvent is selected from one of deionized water, ethanol and NMP.

[0027] Specifically, the mass of the solvent is 1 to 1.5 times the mass of the mixed powder.

[0028] Specifically, in the mixed slurry obtained in step b, the weight ratio of the layered oxide positive electrode material with a highly exposed (010) crystal plane, the conductive agent, and the binder is (16-18):1:(1-2).

[0029] Specifically, the diaphragm type is a polypropylene diaphragm, and the main component of the electrolyte used in the battery is: lithium salt (lithium hexafluorophosphate); preferably, the electrolyte is 1M LiPF6 in EC:EMC=3:7Vol%, with 2wt% vinylene carbonate VC additive added.

[0030] Specifically, in step c, the loading amount of the mixed slurry on the prepared electrode sheet is 1 to 20 mg / cm 2 .

[0031] Furthermore, based on a general inventive concept, the present invention also provides a lithium-ion battery prepared using the layered oxide positive electrode material with a highly exposed (010) crystal plane.

[0032] Compared with the prior art, the advantages of the present invention are:

[0033] 1. The present invention adopts a solid-phase method, and introduces a modified material only during the process of mixing the precursor with the lithium source, inducing the layered oxide positive electrode material to highly expose the (010) crystal plane. The method is simple and does not change the existing industrial production process, and can be quickly promoted on a large scale.

[0034] 2. The preparation method of regulating the highly exposed (010) crystal plane of the layered oxide positive electrode material of the present invention has strong versatility and is applicable to layered oxide single crystal and polycrystalline positive electrode materials with various nickel contents, and the prepared materials have good uniformity.

[0035] 3. While regulating the rate performance of the layered oxide positive electrode material with a high exposed (010) crystal plane, the present invention also achieves doping and coating modification of the material by doping aluminum, nitrogen and silicon elements into the layered oxide positive electrode material, and forming a coating layer of aluminum oxide and silicon oxide, thereby further improving the specific capacity and cycle stability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 LiNi prepared in Comparative Example 1 0.96 Co 0.015 Mn 0.015 Al 0.01 SEM image of O2;

[0037] Figure 2 LiNi prepared in Comparative Example 2 0.83 Co 0.12 Mn 0.05 SEM image of O2;

[0038] Figure 3 LiNi with highly exposed (010) crystal plane prepared in Example 1 0.96 Co 0.015 Mn 0.015 Al 0.01 SEM image of O2;

[0039] Figure 4 LiNi with highly exposed (010) crystal plane prepared in Example 2 0.83 Co 0.12 Mn 0.05 SEM image of O2;

[0040] Figure 5 1 is a rate performance diagram of Comparative Example 1 and Example 1;

[0041] Figure 6 Graph showing the cycling performance of Comparative Example 1 and Example 1 at a rate of 0.5C;

[0042] Figure 7 2 is a rate performance diagram of Comparative Example 2 and Example 2;

[0043] Figure 8 This is a cycle performance diagram of Comparative Example 2 and Example 2 at a 1C rate. DETAILED DESCRIPTION

[0044] The following examples will further illustrate the present invention with reference to the accompanying drawings. This embodiment is implemented based on the technical solution of the present invention and provides detailed implementation methods and processes, but the protection scope of the present invention is not limited to the following examples.

[0045] The experimental methods in the following examples without specific conditions are generally based on conventional conditions, and the raw materials and reagents used are conventional commercial products unless otherwise specified.

[0046] The comparative examples and examples all used Ni 0.96 Co 0.015 Mn 0.015 Al 0.01 (OH)2、Ni 0.83 Co 0.12 Mn 0.05 The (OH)2 layered oxide positive electrode material precursor is used as the raw material, and its preparation method can adopt the conventional method in the prior art, which is not the inventive point of the present invention and will not be described in detail.

[0047] Comparative Example 1

[0048] Ni 0.96 Co 0.015 Mn 0.015 Al 0.01 The (OH)2 layered oxide cathode material precursor and LiOH·H2O were uniformly mixed in a molar ratio of 1:1.03, and then placed in an oxygen atmosphere furnace for two-stage sintering. The first stage sintering temperature was 400℃, the sintering time was 4h, and the second stage sintering temperature was 720℃, the sintering time was 10h, and the layered oxide cathode material LiNi was obtained. 0.96 Co 0.015 Mn 0.015 Al 0.01 O2.

[0049] The layered oxide positive electrode material LiNi obtained in Comparative Example 1 0.96 Co 0.015 Mn 0.015 Al 0.01 The SEM image of O2 is as follows Figure 1 As shown, from Figure 1 It can be seen that the layered oxide positive electrode material LiNi 0.96 Co 0.015 Mn 0.015 Al 0.01 The secondary O2 particles are spherical with a size of 10 μm, and the primary particles are irregular grains.

[0050] Comparative Example 2

[0051] Ni 0.83 Co0.12 Mn 0.05 The (OH)2 layered oxide cathode material precursor and LiOH·H2O were uniformly mixed in a molar ratio of 1:1.03, and then placed in an oxygen atmosphere furnace for two-stage sintering. The first stage sintering temperature was 500℃, the sintering time was 6h, and the second stage sintering temperature was 780℃, the sintering time was 12h, and the layered oxide cathode material LiNi was obtained. 0.83 Co 0.12 Mn 0.05 O2.

[0052] The layered oxide positive electrode material LiNi obtained in Comparative Example 2 0.83 Co 0.12 Mn 0.05 The SEM image of O2 is as follows Figure 2 As shown, from Figure 2 It can be seen that the layered oxide positive electrode material LiNi 0.83 Co 0.12 Mn 0.05 The secondary O2 particles are spherical with a size of 12 μm, and the primary particles are irregular grains.

[0053] Example 1

[0054] Example 1 provides a method for preparing a layered oxide positive electrode material with a highly exposed (010) crystal plane, the specific steps being:

[0055] Ni 0.96 Co 0.015 Mn 0.015 Al 0.01 The (OH)2 layered oxide cathode material precursor, LiOH·H2O, dihydroxyaminoacetic acid aluminum and silicon dioxide were uniformly mixed in a molar ratio of 1:1.03:0.01:0.0065, and then placed in an oxygen atmosphere furnace for two-stage sintering. The first stage sintering temperature was 400℃, the sintering time was 4h, and the second stage sintering temperature was 720℃, the sintering time was 10h, and the layered oxide cathode material LiNi with highly exposed (010) crystal plane was obtained. 0.96 Co 0.015 Mn 0.015 Al 0.01 O2.

[0056] The layered oxide positive electrode material LiNi obtained in Example 1 0.96 Co 0.015 Mn 0.015 Al 0.01 The SEM image of O2 is as follows Figure 3 As shown, from Figure 3 It can be seen that the layered oxide positive electrode material LiNi with high exposed (010) crystal plane in Example 1 0.96 Co0.015 Mn 0.015 Al 0.01 The O2 secondary particles are spherical with a size of 10 μm, and the primary particles are long single crystal grains.

[0057] Example 2

[0058] Example 2 provides a method for preparing a layered oxide positive electrode material with a highly exposed (010) crystal plane, the specific steps being:

[0059] Ni 0.83 Co 0.12 Mn 0.05 The (OH)2 layered oxide cathode material precursor, LiOH·H2O, dihydroxyaminoacetic acid aluminum and silicon dioxide were uniformly mixed in a molar ratio of 1:1.03:0.01:0.0065, and then placed in an oxygen atmosphere furnace for two-stage sintering. The first stage sintering temperature was 500℃, the sintering time was 6h, and the second stage sintering temperature was 780℃, the sintering time was 12h, and the layered oxide cathode material LiNi with highly exposed (010) crystal plane was obtained. 0.83 Co 0.12 Mn 0.05 O2.

[0060] Layered oxide positive electrode material LiNi obtained in Example 2 0.83 Co 0.12 Mn 0.05 The SEM image of O2 is as follows Figure 4 As shown, from Figure 4 It can be seen that the layered oxide positive electrode material LiNi with high exposed (010) crystal plane in Example 2 0.83 Co 0.12 Mn 0.05 The O2 secondary particles are spherical with a size of 12 μm, and the primary particles are long single crystal grains.

[0061] Performance Testing

[0062] The products prepared in Example 1-2 and Comparative Example 1-2 were used to prepare lithium-ion batteries. The specific preparation method was as follows:

[0063] a. The active material (layered oxide positive electrode material prepared in Examples 1 and 2 or Comparative Examples 1 and 2) was mixed with carbon black (Super-P, conductive agent, Shenzhen Kejing Zhida Technology Co., Ltd., CAS1333-86-4) and a binder PVDF (polyvinylidene fluoride) in a mass ratio of 90:5:5 to obtain a mixed powder;

[0064] b. The mixed powder in step a is then added to a solvent (N-methylpyrrolidone, NMP) and placed in a mixing container to mix evenly. The mass of the solvent is 1.5 times the mass of the mixed powder, and then ultrasonically dispersed at a power of 100 W for 8 minutes. Then, a polytetrafluoroethylene magnet is placed in the mixing container and stirred at a speed of 400 r / min for 10 hours to uniformly disperse the active substance and carbon black (Super-P) to obtain a mixed slurry;

[0065] c. The mixed slurry in step b was coated on aluminum foil and dried at 80 ° C for 12 h to prepare a loading of 5 mg / cm 2 electrode sheet; then, in an argon-protected glove box, the prepared electrode sheet was used as the working electrode, the metal lithium sheet was used as the counter electrode, the polypropylene film was used as the separator, the electrolyte was a high-nickel 4.6V electrolyte (1M LiPF6, EC:EMC=3:7Vol%, with 2wt% vinylene carbonate VC additive), a button battery was assembled, the battery model was a CR2032 button battery, and constant current charge and discharge tests were performed.

[0066] Comparing the rate performance of Example 1 and Comparative Example 1, the discharge specific capacity was tested at different rates. Figure 5 shown.

[0067] As can be seen from the figure, the discharge capacity of Example 1 at 0.1C is 238mAh / g, which is higher than the 220mAh / g of Comparative Example 1. As the rate increases, the discharge capacity of Example 1 and Comparative Example 1 decreases, but the reduction in Example 1 is much lower than that in Comparative Example 1. At a high rate of 5C, the discharge capacity of Example 1 is still 192mAh / g, while the discharge capacity of Comparative Example 1 is only 153mAh / g. The results show that the preparation method of the layered oxide positive electrode material with high exposure (010) crystal plane proposed in the present invention is beneficial to LiNi 0.96 Co 0.015 Mn 0.015 Al 0.01 Improvement of the rate performance of O2 materials.

[0068] Comparing the cycle performance of Example 1 and Comparative Example 1, the cycle performance at 0.5C rate is shown in the figure below. Figure 6 shown.

[0069] As can be seen from the figure, the initial discharge specific capacity of Example 1 is 216 mAh / g, which is higher than 170 mAh / g of Comparative Example 1. The capacity retention rate of Example 1 after 200 cycles is 76%, which is much higher than 38% of Comparative Example 1. The results show that the preparation method of the layered oxide positive electrode material with high exposed (010) crystal plane proposed in the present invention is beneficial to LiNi 0.96 Co 0.015 Mn 0.015 Al0.01 Improvement of O2 material cycle performance.

[0070] Comparing the rate performance of Example 2 and Comparative Example 2, the discharge specific capacity was tested at different rates. Figure 7 shown.

[0071] As can be seen from the figure, the discharge capacity of Example 2 at 0.1C is 197mAh / g, which is higher than 196mAh / g of Comparative Example 2. As the rate increases, the discharge capacity of Example 2 and Comparative Example 2 decreases, but the reduction in Example 2 is lower than that in Comparative Example 2. At a high rate of 5C, the discharge capacity of Example 2 is still 142mAh / g, which is higher than 132mAh / g of Comparative Example 2. The results show that the preparation method of the layered oxide positive electrode material with high exposure (010) crystal plane proposed in the present invention is beneficial to LiNi 0.83 Co 0.12 Mn 0.05 Improvement of the rate performance of O2 materials.

[0072] Comparing the cycle performance of Example 2 and Comparative Example 2, the cycle performance at 1C rate is shown in the figure below. Figure 8 shown.

[0073] As can be seen from the figure, the initial discharge specific capacity of Example 2 is 179 mAh / g, which is higher than 175 mAh / g of Comparative Example 2. The capacity retention rate of Example 2 after 100 cycles is 98%, which is higher than 94% of Comparative Example 2. The results show that the preparation method of the layered oxide positive electrode material with high exposed (010) crystal plane proposed in the present invention is beneficial to LiNi 0.83 Co 0.12 Mn 0.05 Improvement of O2 material cycle performance.

[0074] In summary, the preparation method of regulating the highly exposed (010) crystal plane of the layered oxide positive electrode material described in the present invention is simple and can effectively improve its overall performance. It has the characteristics of low price and good versatility, and is suitable for large-scale industrial promotion and application.

[0075] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. Application of a layered oxide cathode material with a highly exposed (010) crystal plane in the preparation of a lithium-ion battery, characterized in that: The layered oxide cathode material with a high exposure of (010) crystal plane is made into a CR2032 button-type lithium-ion battery, which has good charge and discharge performance, rate performance and cycle stability; a. The layered oxide cathode material having a highly exposed (010) crystal plane is mixed with carbon black Super-P, model CAS 1333-86-4, and a binder PVDF in a mass ratio of 90:5:5 to obtain a mixed powder; b. The mixed powder in step a is then added to the solvent NMP and placed in a mixing container for uniform mixing. The mass of the solvent is 1.5 times the mass of the mixed powder. The mixture is then ultrasonically dispersed at a power of 100 W for 8 minutes. A polytetrafluoroethylene magnet is then placed in the mixing container and stirred at a speed of 400 r / min for 10 hours to uniformly disperse the layered oxide cathode material with a highly exposed (010) crystal plane and the carbon black Super-P to obtain a mixed slurry. c. The mixed slurry in step b was coated on aluminum foil and dried at 80 ° C for 12 h to prepare a loading of 5 mg / cm 2 Then, in an argon-protected glove box, a button battery was assembled using the prepared electrode sheet as the working electrode, the metal lithium sheet as the counter electrode, a polypropylene film as the separator, and a high-nickel 4.6V electrolyte. The battery model was a CR2032 button battery. The electrolyte includes 1M LiPF6, EC:EMC=3:7 Vol%, and 2 wt% vinylene carbonate VC additive; The layered oxide positive electrode material with a highly exposed (010) crystal plane is prepared by the following steps: The layered oxide cathode material precursor, lithium source, aluminum nitrogen compound and silicon-containing compound are uniformly mixed in a certain molar ratio, and then placed in an atmosphere furnace for sintering to obtain a layered oxide cathode material with a highly exposed (010) crystal plane; The chemical formula of the layered oxide cathode material precursor is Ni 0.96 Co 0.015 Mn 0.015 Al 0.01 (OH)2, Ni 0.83 Co 0.12 Mn 0.05 (OH)2; The lithium source is lithium hydroxide; The aluminum nitrogen compound is dihydroxy aminoacetic acid aluminum; The silicon-containing compound is silicon dioxide; The molar ratio of the layered oxide positive electrode material precursor, lithium source, aluminum nitrogen compound and silicon-containing compound is 1:1.03:0.01:0.0065; The sintering includes one-stage sintering and two-stage sintering; the temperature of the one-stage sintering is 400° C.; the time of the one-stage sintering is 4 hours; the temperature of the two-stage sintering is 720° C.; the time of the two-stage sintering is 10 hours.

2. The use according to claim 1, wherein: The atmosphere in the atmosphere furnace is any one of oxygen atmosphere, nitrogen atmosphere, ammonia atmosphere, sulfur dioxide atmosphere and hydrogen sulfide atmosphere.

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