A double-doped single-crystal ultrahigh-nickel positive electrode material, a preparation method therefor, and an application thereof

Abstract

The application discloses a kind of double-doped single-crystal super-high nickel positive electrode material and its preparation method and application, and the positive electrode material is mainly made by the following method: (1) nano nickel oxide or also nano cobaltic oxide, nano manganese dioxide, with boron source and aluminum source ball milling is uniformly mixed, and mixed powder is obtained;(2) the mixed powder obtained in step (1) is uniformly mixed with lithium source, then two-stage microwave sintering is carried out in oxidizing atmosphere, and the furnace is cooled to room temperature, grinding and crushing are carried out, and double-doped single-crystal super-high nickel positive electrode material is obtained.The positive electrode sheet made of the double-doped single-crystal super-high nickel positive electrode material is used in the field of lithium ion battery.The positive electrode material of the application has dense crystal grains, stable structure, high crystallinity and low Li / Ni mixing arrangement.The high-rate performance and cycle performance of the battery assembled by the electrode sheet are excellent.The method of the application is simple, fast, green and environmentally friendly, energy-saving and cost-reducing, and suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to a single-crystal ultrahigh nickel positive electrode material and a preparation method and application thereof, in particular to a double-doped single-crystal ultrahigh nickel positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] High-nickel single-crystal positive electrode materials (such as LiNi x Co y Mn 1-x-y O2, 0.9≤x<1.0, 0≤y≤0.1) are core materials for lithium-ion batteries to achieve a high energy density of 400 Wh / kg, and have attracted much attention in recent years. The single-crystal structure of the material significantly improves the cycle stability by eliminating the grain boundary cracks and interface side reactions of polycrystalline materials. However, the traditional preparation technology faces severe challenges: the high-temperature solid-phase method requires multi-stage calcination (>12 h) and multi-step preparation (first preparing a precursor, and then preparing a positive electrode material), which has high energy consumption and is prone to cause Li / Ni mixing (>4%) and grain coarsening (>5 μm); the coprecipitation-calcination method can control the particle morphology, but the process is complex, the wastewater treatment cost is high, and the secondary particles are prone to crack along the grain boundaries during the cycle.

[0003] CN110112403A discloses a high-specific-capacity lithium nickel cobalt manganese oxide positive electrode material and a preparation method thereof. Nickel sulfate, cobalt sulfate, manganese sulfate, and aluminum sulfate are mixed and dissolved in proportion to prepare a metal sulfate solution; then NaOH and NH3·H2O are added to the solution to adjust the pH to 11, the solution is stirred, and the precipitate is collected by centrifugation and vacuum dried to obtain an aluminum-doped nickel cobalt manganese hydroxide precursor; the precursor is further mixed with LiOH·H2O in an excess of 5%, 1wt% B2O3, and 0.5wt% SiO2 by ball milling, and the mixture is sintered at 850°C for 12 h, and then naturally cooled to obtain a lithium nickel cobalt manganese oxide positive electrode material. Although this method can effectively improve the cycle performance of the lithium manganese oxide battery and inhibit the self-discharge phenomenon, the method needs to be prepared by coprecipitation combined with solid-phase sintering, which has a long process time and high energy consumption.

[0004] CN114400320A discloses a high-temperature stable positive electrode material and a preparation method and application thereof. The positive electrode material is prepared by a step-by-step process of high-temperature sintering of a lithium nickel cobalt manganese oxide substrate, medium-temperature oxidation of a composite coating, and low-temperature deposition of a bifluorophosphate layer. Although the material obtained by this method has high voltage capacity and high-temperature cycle stability, the method needs to be carried out in steps, i.e., high-temperature sintering, composite oxide coating, and bifluorophosphate deposition, which is complicated and has strict control of parameters such as temperature gradient and atmosphere switching, increasing the difficulty of industrialization and energy consumption cost.

[0005] CN114656000A discloses a nickel cobalt manganese lithium material, a preparation method thereof, a positive electrode material and a lithium ion battery, which is prepared from a lithium source, a nickel cobalt manganese precursor and a trivalent / pentavalent antimony source (molar ratio 1:0.9-1.1) as raw materials, realizes directional doping of the antimony element through a two-stage double-platform sintering method, mixes the pentavalent antimony source first to perform high-temperature step sintering, makes Sb 5+ embed transition metal sites, and then introduces a trivalent antimony source for secondary step sintering, uses Sb 3+ with a larger ionic radius to preferentially occupy lithium sites, and cooperatively stabilizes the bulk phase and surface structure through a multi-stage temperature control strategy with a temperature difference of >200 DEG C and a time difference of >1 h. Although the material obtained by this method can effectively inhibit the electrolyte side reaction and transition metal dissolution, and significantly improve the lithium ion diffusion efficiency, high-temperature safety and long cycle capacity retention rate, this method is still a traditional step-by-step solid-phase sintering method, which has a long process time and high energy consumption.

[0006] In summary, it is urgent to find a kind of double-doped single-crystal super-high nickel positive electrode material and its preparation method and application, which has dense crystal grains, stable structure, high crystallinity and low Li / Ni mixing, and the battery assembled by the electrode plate made of the material has excellent high-rate performance and cycle performance, and the process is simple, fast, green, energy-saving, cost-saving and suitable for industrial production. SUMMARY

[0007] The technical problem to be solved by the present application is to overcome the above-mentioned defects existing in the prior art, and to provide a kind of double-doped single-crystal super-high nickel positive electrode material and its preparation method and application, which has dense crystal grains, stable structure, high crystallinity and low Li / Ni mixing, and the battery assembled by the electrode plate made of the material has excellent high-rate performance and cycle performance, and the process is simple, fast, green, energy-saving, cost-saving and suitable for industrial production.

[0008] The technical solution adopted by the present application to solve its technical problem is as follows: a kind of double-doped single-crystal super-high nickel positive electrode material is mainly prepared by the following method:

[0009] (1) Nanometer nickel oxide or also nanometer cobalt tetraoxide, nanometer manganese dioxide, boron source and aluminum source are ball milled and uniformly mixed to obtain a mixed powder;

[0010] (2) The mixed powder obtained in step (1) is uniformly mixed with a lithium source, then two-stage microwave sintering is carried out in an oxidizing atmosphere, the furnace is cooled to room temperature, and grinding and crushing are carried out to obtain a double-doped single-crystal super-high nickel positive electrode material.

[0011] The inventive idea of the present application is: the present application sintered the high-nickel positive electrode material through the synergistic effect of microwave-assisted nanometer oxide one-step method, avoiding the selective precipitation deviation of metal ions in coprecipitation, B 3+ , Al 3+The double doping in the bulk phase of the high-nickel positive electrode material inhibits lattice distortion, cooperatively controls the material lattice structure and enhances the structural stability. Meanwhile, the boron source and aluminum source also act as sintering solvents to promote the reaction. In combination with the advantages of microwave bulk heating, rapid and low-energy consumption synthesis is achieved. The obtained material has the characteristics of high crystallinity, low Li / Ni mixing, excellent cycle stability and high-rate performance, and is suitable for high-energy-density scenarios such as power batteries.

[0012] Preferably, in step (1), the average particle size of the nano nickel oxide, nano cobalt tetraoxide and nano manganese dioxide is 30-100 nm. The one-step nano-oxide method directly uses nano-scale precursors (NiO, Co3O4, MnO2) to skip the co-precipitation step. The technical breakthroughs are as follows: 1) atomic-level uniform doping: the high specific surface energy of nano-particles promotes the bulk diffusion of B 3 + , Al 3+ dopants to form a gradient solid solution structure, relieving H2-H3 phase transition stress; 2) controllability of single crystal nucleation: the high surface energy of nano-precursors reduces the sintering activation energy, combined with microwave rapid heating to inhibit secondary particle agglomeration, achieving single crystal size consistency (deviation <10%); 3) process simplification and environmental protection: eliminating co-precipitation, washing and other processes, reducing wastewater discharge by >70%, suitable for cobalt-free / low-cobalt system development.

[0013] Preferably, in step (1), the molar ratio of nickel element in the nano nickel oxide, cobalt element in the nano cobalt tetraoxide and manganese element in the nano manganese dioxide is 90-95:0-10:0-10 (more preferably 90-95:1-9:1-9, and further more preferably 90-95:2-6:2-6).

[0014] Preferably, in step (1), the mass ratio of the nano nickel oxide or the nano cobalt tetraoxide and the nano manganese dioxide to the boron source and the aluminum source is 94-99:1-6. A small amount of doping can effectively adjust the electronic structure of the material and inhibit lattice distortion, while excessive doping can destroy the crystal structure of the host material, form inactive phases, hinder ion diffusion and reduce the energy density of the battery.

[0015] Preferably, in step (1), the mass ratio of the boron source to the aluminum source is 1-4:1-4. If the boron source is too much, it may excessively inhibit grain growth, resulting in insufficient mechanical strength of the material. If the aluminum source is too much, it may reduce the electrical conductivity and affect the performance of the material.

[0016] Preferably, in step (1), the boron source includes one or more of boric acid, boron oxide or lithium borate. Since boric acid has a low high-temperature decomposition temperature, it is easy to mix with the precursors and has a low cost. More preferably, the boron source is boric acid.

[0017] Preferably, in step (1), the aluminum source includes one or more of aluminum fluoride, aluminum oxide, or lithium aluminate, etc. Since Al 3+ has a synergistic effect with F - , it can not only stabilize the crystal lattice structure through Al 3+ , but also passivate the surface and inhibit oxygen activity through F - , thereby comprehensively improving the thermal stability, cycle life, and safety of high-nickel single-crystal materials. More preferably, the aluminum source is aluminum fluoride.

[0018] Preferably, in step (1), the mass ratio of the mixed powder to the ball milling beads is 1:5-20 (more preferably 1:5-15), the mixed rotation speed of the ball milling is 200-800 rpm (more preferably 200-600 rpm), and the time is 5-20 h (more preferably 5-12 h). Ball milling mixing is more uniform.

[0019] Preferably, in step (2), the molar ratio of the total number of moles of nickel elements in the nano-nickel oxide, cobalt elements in the nano-tricobalt tetraoxide, and manganese elements in the nano-manganese dioxide to the number of moles of lithium elements in the lithium source is 1:1.03-1.20.

[0020] Preferably, in step (2), the lithium source includes one or more of lithium hydroxide monohydrate, lithium carbonate, or lithium nitrate, etc.

[0021] Preferably, in step (2), the flow rate of the oxidation atmosphere is 50-200 sccm.

[0022] Preferably, in step (2), the oxidation atmosphere includes oxygen and / or air, etc.

[0023] Preferably, in step (2), in the microwave sintering, the output power of the microwave is 200-2900 W (more preferably 800-1200 W), and the microwave frequency is 2.45 GHz.

[0024] Preferably, in step (2), the two-stage microwave sintering refers to: first, heating from room temperature to 400-600°C at a rate of 50-100°C / min, and holding for 5-60 min (more preferably 20-60 min) for one-stage microwave sintering, and then heating to 750-950°C at a rate of 50-100°C / min, and holding for 5-60 min (more preferably 20-60 min) for two-stage microwave sintering. Microwave sintering realizes uniform bulk heating through the dielectric loss of materials (such as ion conduction and dipole polarization of NiO and LiOH), and its core advantages are reflected in three aspects: 1) ultrafast reaction kinetics: the heating rate can reach more than 100°C / min, the sintering time is shortened to 1 / 5 of that of traditional processes, the abnormal growth of crystal grains is inhibited, and submicron single crystals are obtained; 2) precise structure control: the microwave electric field drives Li+ Migration, reduce Li / Ni mixing degree to below 2%, at the same time, O2 atmosphere dynamic regulation and control stable Ni 3+ Oxidation state, reduce oxygen vacancy defects; 3) energy saving: energy utilization rate is 80% (traditional method < 40%), lithium volatilization loss rate < 3%, and comprehensive cost is reduced by 40%.

[0025] In summary, the synergistic effect of nanoscale raw materials and microwave sintering further releases the performance potential, the microwave field accelerates the densification of nanoparticles (for example, NCM single crystal synthesis can be completed at 850 DEG C / 30 min), and the grain boundary migration is optimized through the coupling of electric field and thermal field, so that the cycle stability and rate performance of the material are greatly improved, and a revolutionary path for high safety and high energy density of power batteries is provided. In the future, with the development of large-scale microwave equipment and standardized nanometer precursors, this green synthesis technology is expected to promote the large-scale commercial application of high-nickel single crystal materials.

[0026] The technical scheme adopted by the application to solve the technical problems is as follows: an application of a double-doped single-crystal ultra-high-nickel positive electrode material, and a positive electrode sheet made of the double-doped single-crystal ultra-high-nickel positive electrode material is used in the field of lithium ion batteries.

[0027] The beneficial effects of the application are as follows:

[0028] (1) The double-doped single-crystal ultra-high-nickel positive electrode material has dense crystal grains, stable structure, high crystallinity and low Li / Ni mixing degree, and the battery assembled by the electrode sheet has a first reversible discharge specific capacity of 222.82 mAh / g at 0.1C rate, and a first coulombic efficiency of 85.67%; the first discharge specific capacity is 193.3 mAh / g, 183.4 mAh / g, 174.1 mAh / g and 153.4 mAh / g at 1C, 2C, 3C and 5C rates, respectively; and the discharge capacity retention rate can still reach 83.15% after 200 cycles at 0.5C, which indicates that the double-doped single-crystal ultra-high-nickel positive electrode material has excellent high-rate performance and cycle performance.

[0029] (2) The combination of nanometer oxides and microwave sintering in the method is a key technology for breaking through the bottleneck of preparation of high-nickel single crystal materials, the high surface energy of nanoparticles reduces the sintering activation energy, and the densification process is further accelerated in cooperation with microwave heating, and the process is simple, fast, green, energy-saving, cost-saving, and suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is an SEM diagram of the double-doped single-crystal ultra-high-nickel positive electrode material of the application, embodiment 1;

[0031] Figure 2is the first circle charge-discharge diagram of the battery assembled by the electrode pole piece of the double-doped single-crystal super-high nickel positive electrode material embodiment 1 of the application;

[0032] Figure 3 is the rate performance comparison diagram of the battery assembled by the electrode pole piece of the double-doped single-crystal super-high nickel positive electrode material embodiment 1, comparative example 1 of the application;

[0033] Figure 4 is the cycle performance comparison diagram of the battery assembled by the electrode pole piece of the double-doped single-crystal super-high nickel positive electrode material embodiment 1, comparative example 1 of the application. DETAILED DESCRIPTION

[0034] The application will be further described below in combination with embodiments and drawings.

[0035] The average particle size of the nano nickel oxide used in the embodiment of the application is 30 nm, the average particle size of the nano cobalt trioxide tetraoxide is 50 nm, and the average particle size of the nano manganese dioxide is 100 nm, which are all purchased from Aladdin Chemical Reagent Network; The raw materials or chemical reagents used in the embodiment and comparative example of the application are all obtained through conventional commercial channels, unless otherwise specified.

[0036] A double-doped single-crystal super-high nickel positive electrode material embodiment 1

[0037] and mainly prepared by the following method:

[0038] (1) 2.017 g (27 mmol) of nano nickel oxide, 0.120 g (0.5 mmol) of nano cobalt trioxide tetraoxide, and 0.130 g (1.5 mmol) of nano manganese dioxide are mixed with 0.0398 g of H3BO3 and 0.0796 g of AlF3, and the mass ratio of the mixed powder to the ball milling beads is 1:5, the mixing speed is 200 rpm, and the ball milling is performed for 5 h until the mixture is uniformly mixed to obtain a mixed powder;

[0039] (2) The mixed powder obtained in step (1) is uniformly mixed with 1.322 g (31.50 mmol) of LiOH·H2O, and then two-stage microwave sintering is performed in an oxygen atmosphere with a flow rate of 50 sccm, an output power of 900 W, and a microwave frequency of 2.45 GHz: first, the temperature is raised from room temperature to 400℃ at a rate of 50℃ / min, and the first-stage microwave sintering is performed for 60 min, and then the temperature is raised to 850℃ at a rate of 50℃ / min, and the second-stage microwave sintering is performed for 60 min, and the furnace is cooled to room temperature, and the powder is ground and crushed to obtain a double-doped single-crystal super-high nickel positive electrode material LiNi 0.9 Co 0.05 Mn 0.05 O2.

[0040] For example, Figure 1As shown, the double-doped single-crystal ultra-high nickel cathode material obtained in the embodiments of the present invention is micron-sized bulk particles with a particle size of 1 to 6 μm.

[0041] Application Example 1 of a Double-Doped Single-Crystal Ultra-High Nickel Cathode Material

[0042] The cathode sheet made from the double-doped single-crystal ultra-high nickel cathode material obtained in the embodiments of the present invention is used to assemble a coin cell lithium-ion battery.

[0043] Method for preparing the positive electrode: In a dew point room, 0.8g of the double-doped single-crystal ultra-high nickel positive electrode material obtained in this embodiment of the invention, 0.1g of conductive carbon black, and 0.1g of polyvinylidene fluoride are ground until no obvious particles are visible. Further, 1mL of N-methylpyrrolidone solution is added to the above mixture, and grinding continues until a homogeneous slurry is formed. The prepared slurry is coated onto the current collector aluminum foil, ensuring the slurry adheres evenly to the current collector surface. Finally, after drying at 120 °C for 6 h, holes are punched to form a 12 mm diameter SNCM positive electrode.

[0044] Assemble a button lithium-ion battery: Place the obtained SNCM positive electrode sheet into the positive electrode shell and add an appropriate amount of electrolyte to wet the electrode; then cover with a separator, place the lithium sheet and stack the gasket and spring sheet; finally align the negative electrode shell and press and seal it with a sealing machine; after assembly, it needs to stand for 18 hours to allow the electrolyte to fully wet it before charging and discharging tests are performed.

[0045] Battery testing: The coin-type lithium-ion battery assembled according to the application embodiment of this invention was tested for its initial charge-discharge specific capacity at 0.1 C under the conditions of a discharge cutoff voltage of 2.75V and a charging cutoff voltage of 4.4V. The test results are shown in Table 1. Figure 2 As shown; its rate performance was tested at 0.1 C, 0.2 C, 0.3 C, 0.5 C, 1 C, 2 C, 3 C, and 5 C, and the test results are as follows. Figure 3 As shown in Table 1, after 3 cycles of activation at 0.1C, the system was charged at 0.5C and discharged at 0.5C for 200 cycles to test its cycle performance. Figure 4 As shown.

[0046] like Figure 2 As shown, the coin-type lithium-ion battery assembled in the application embodiment of the present invention has a first charge-discharge specific capacity of 259.04 mAh / g and 213.80 mAh / g at 0.1C, respectively, and a coulombic efficiency of 82.54%.

[0047] like Figure 3As shown, the first discharge specific capacity of the buckle type lithium ion battery assembled by the application application example is 216.9 mAh / g, 212.3 mAh / g, 207.7 mAh / g, 201.9 mAh / g, 193.3 mAh / g, 183.4 mAh / g, 174.1 mAh / g, and 153.4 mAh / g at 0.1 C, 0.2 C, 0.3 C, 0.5 C, 1 C, 2 C, 3 C, and 5 C, respectively. When the rate returns to 0.1 C, the first discharge specific capacity can still reach 203.2 mAh / g, the rate performance is excellent, and it is proved that the doping of boron and aluminum and the microwave two-stage sintering can promote the complete growth of single crystals, shorten the diffusion path of lithium ion batteries, and improve the rate performance.

[0048] As shown in the application example of the application, Figure 4 The first discharge specific capacity of the buckle type lithium ion battery assembled by the application application example is 202.4 mAh / g at 0.5 C, and the discharge specific capacity can still reach 168.3 mAh / g after 200 cycles, and the capacity retention rate is 83.15%.

[0049] A double-doped single-crystal ultra-high nickel positive electrode material embodiment 2

[0050] Mainly made by the following method:

[0051] (1) 2.062 g (27.6 mmol) of nano nickel oxide, 0.048 g (0.2 mmol) of nano cobalt tetraoxide, and 0.156 g (1.8 mmol) of nano manganese dioxide are mixed with 0.0231 g H3BO3 and 0.0231 g AlF3, the mass ratio of mixed powder to ball milling beads is 1:8, the mixing speed is 300 rpm, and the ball milling is carried out for 8 h until the mixture is uniformly mixed, to obtain a mixed powder;

[0052] (2) The mixed powder obtained in step (1) is uniformly mixed with 1.385 g (33.0 mmol) of LiOH·H2O, and then two-stage microwave sintering is carried out in an oxygen atmosphere with a flow rate of 80 sccm, the output power of the microwave is 800 W, and the microwave frequency is 2.45 GHz: first, the temperature is raised from room temperature to 450℃ at a rate of 60℃ / min, and the temperature is kept for 50 min for one-stage microwave sintering, then the temperature is raised to 800℃ at a rate of 60℃ / min, and the temperature is kept for 50 min for two-stage microwave sintering, and the furnace is cooled to room temperature, and then the powder is ground and crushed to obtain a double-doped single-crystal ultra-high nickel positive electrode material LiNi 0.92 Co 0.02 Mn 0.06 O2.

[0053] The double-doped single-crystal ultrahigh nickel positive electrode material obtained by the embodiment of the application is micron-level blocky particles with a particle size of 1-6 μm.

[0054] An application example 2 of a double-doped single-crystal ultrahigh nickel positive electrode material

[0055] The positive electrode sheet made of the double-doped single-crystal ultrahigh nickel positive electrode material obtained by the embodiment of the application is used to assemble a button lithium ion battery.

[0056] The positive electrode sheet preparation method is the same as that in the application example 1.

[0057] The button lithium ion battery is assembled in the same manner as in the application example 1.

[0058] The battery test: the first charge-discharge specific capacity and cycle performance test are the same as those in the application example 1; and the test results are shown in Table 1.

[0059] An application example 2 of a double-doped single-crystal ultrahigh nickel positive electrode material

[0060] The double-doped single-crystal ultrahigh nickel positive electrode material is mainly prepared by the following method:

[0061] (1) 2.106 g (28.2 mmol) of nano nickel oxide, 0.048 g (0.2 mmol) of nano cobalt tetraoxide and 0.104 g (1.2 mmol) of nano manganese dioxide are mixed with 0.0466 g of H3BO3 and 0.0233 g of AlF3, the mass ratio of the mixed powder to the ball milling beads is 1:10, the mixing speed is 400 rpm, and the ball milling is performed for 10 h until the mixture is uniformly mixed to obtain a mixed powder;

[0062] (2) the mixed powder obtained in step (1) is uniformly mixed with 1.448 g (34.5 mmol) of LiOH·H2O, and then two-stage microwave sintering is performed in an oxygen atmosphere with a flow rate of 100 sccm, the output power of the microwave is 900 W, and the microwave frequency is 2.45 GHz: first, the temperature is raised to 500 ℃ at a rate of 70 ℃ / min, and the first-stage microwave sintering is performed for 40 min, then the temperature is raised to 850 ℃ at a rate of 70 ℃ / min, and the second-stage microwave sintering is performed for 40 min, the furnace is cooled to room temperature, and the powder is ground and crushed to obtain a double-doped single-crystal ultrahigh nickel positive electrode material LiNi 0.94 Co 0.02 Mn 0.04 O2.

[0063] The double-doped single-crystal ultrahigh nickel positive electrode material obtained by the embodiment of the application is micron-level blocky particles with a particle size of 1-6 μm.

[0064] An application example 2 of a double-doped single-crystal ultrahigh nickel positive electrode material

[0065] The positive electrode sheet made of the double-doped single-crystal ultrahigh-nickel positive electrode material obtained in the embodiment of the application is used to assemble a button-type lithium ion battery.

[0066] The positive electrode sheet preparation method is the same as that in Application Example 1.

[0067] The button-type lithium ion battery is assembled in the same manner as in Application Example 1.

[0068] The battery test: the first charge-discharge specific capacity and cycle performance test are the same as those in Application Example 1; and the test results are shown in Table 1.

[0069] A double-doped single-crystal ultrahigh-nickel positive electrode material embodiment 4

[0070] The double-doped single-crystal ultrahigh-nickel positive electrode material is mainly prepared by the following method:

[0071] (1) 2.129 g (28.5 mmol) of nano-nickel oxide, 0.048 g (0.2 mmol) of nano-tricobalt tetroxide, and 0.078 g (0.9 mmol) of nano-manganese dioxide are mixed with 0.0235 g of H3BO3 and 0.0705 g of AlF3, and the mixed powder and the ball milling beads are ball milled at a mass ratio of 1:12 and a mixing speed of 500 rpm for 12 h until the mixture is uniform, to obtain a mixed powder;

[0072] (2) The mixed powder obtained in step (1) is uniformly mixed with 1.511 g (36.0 mmol) of LiOH·H2O, and then subjected to two-stage microwave sintering in an oxygen atmosphere at a flow rate of 120 sccm, at an output power of 800 W and a microwave frequency of 2.45 GHz: first, the temperature is raised from room temperature to 550℃ at a rate of 80℃ / min, and then the temperature is maintained at 550℃ for 30 min to perform the first-stage microwave sintering; then, the temperature is raised to 900℃ at a rate of 80℃ / min, and then the temperature is maintained at 900℃ for 30 min to perform the second-stage microwave sintering; the furnace is cooled to room temperature, and the product is ground and crushed to obtain a double-doped single-crystal ultrahigh-nickel positive electrode material LiNi 0.95 Co 0.02 Mn 0.03 O2.

[0073] It is detected that the double-doped single-crystal ultrahigh-nickel positive electrode material obtained in the embodiment of the application is a micron-level blocky particle with a particle size of 1-6 μm.

[0074] A double-doped single-crystal ultrahigh-nickel positive electrode material application embodiment 4

[0075] The positive electrode sheet made of the double-doped single-crystal ultrahigh-nickel positive electrode material obtained in the embodiment of the application is used to assemble a button-type lithium ion battery.

[0076] The positive electrode sheet preparation method is the same as that in Application Example 1.

[0077] The button-type lithium ion battery is assembled in the same manner as in Application Example 1.

[0078] Battery test: the first charge-discharge specific capacity and cycle performance test is same as application example 1; the test result is shown in table 1.

[0079] A double-doped single-crystal ultrahigh nickel positive electrode material example 5

[0080] Mainly made by the following method:

[0081] (1) 2.084 g (27.9 mmol) of nano nickel oxide, 0.048 g (0.2 mmol) of nano cobalt tetraoxide and 0.130 g (1.5 mmol) of nano manganese dioxide are mixed with 0.0952 g H3BO3 and 0.0239 g AlF3, and the mass ratio of mixed powder to ball milling beads is 1:15, the mixing speed is 600 rpm, and the ball milling is carried out for 10 h until the mixture is uniformly mixed to obtain a mixed powder;

[0082] (2) the mixed powder obtained in step (1) is uniformly mixed with 1.385 g (33.0 mmol) of LiOH·H2O, and then two-stage microwave sintering is carried out in an oxygen atmosphere with a flow rate of 200 sccm, an output power of 900 W and a microwave frequency of 2.45 GHz: first, the temperature is raised to 600℃ at a rate of 100℃ / min, and the first-stage microwave sintering is carried out for 20 min, and then the temperature is raised to 950℃ at a rate of 100℃ / min, and the second-stage microwave sintering is carried out for 20 min, and the furnace is cooled to room temperature, and the powder is ground and crushed to obtain a double-doped single-crystal ultrahigh nickel positive electrode material LiNi 0.93 Co 0.02 Mn 0.05 O2.

[0083] It is detected that the double-doped single-crystal ultrahigh nickel positive electrode material obtained in the embodiment of the application is a micron-level blocky particle with a particle size of 1-6 μm.

[0084] A double-doped single-crystal ultrahigh nickel positive electrode material application example 5

[0085] The positive electrode sheet made of the double-doped single-crystal ultrahigh nickel positive electrode material obtained in the embodiment of the application is used to assemble a button-type lithium ion battery.

[0086] The positive electrode sheet preparation method is same as application example 1.

[0087] The button-type lithium ion battery is assembled same as application example 1.

[0088] Battery test: the first charge-discharge specific capacity and cycle performance test is same as application example 1; the test result is shown in table 1.

[0089] Comparative example 1

[0090] The difference between the present comparative example and Example 1 is only that in step (2), one-stage microwave sintering is performed: the temperature is raised to 750℃ at a rate of 50℃ / min, and the temperature is kept for 60 min. The rest is the same as in Example 1.

[0091] Positive electrode tab preparation method: the same as in Application Example 1.

[0092] Assembled button lithium ion battery: the same as in Application Example 1.

[0093] Battery test: the same as in Application Example 1; the test results are shown in Table 1, Figure 3 , 4 .

[0094] As shown in Table 1, Figure 3 , the first discharge specific capacity of the button lithium ion battery assembled in the present comparative example is only 202.0 mAh / g, 193.6 mAh / g, 191.9 mAh / g, 181.9 mAh / g, 170.9 mAh / g, 158.0 mAh / g, 145.2 mAh / g, and 124.3 mAh / g at 0.1 C, 0.2 C, 0.3 C, 0.5 C, 1 C, 2 C, 3 C, and 5 C, respectively. When the rate returns to 0.1 C, the first discharge specific capacity is only 181.2 mAh / g, and the rate performance is poor. This shows that one-stage sintering makes the decomposition of the precursor and the formation rate of the crystal nucleus too fast, which leads to disordered crystal growth direction, easy formation of polycrystalline structure or secondary particles, and significant hindering of lithium ion diffusion by the crystal boundary, thereby reducing the rate performance.

[0095] As shown in Table 1, Figure 4 , the first discharge specific capacity of the button lithium ion battery assembled in the present comparative example is only 202.0 mAh / g, 193.6 mAh / g, 191.9 mAh / g, 181.9 mAh / g, 170.9 mAh / g, 158.0 mAh / g, 145.2 mAh / g, and 124.3 mAh / g at 0.1 C, 0.2 C, 0.3 C, 0.5 C, 1 C, 2 C, 3 C, and 5 C, respectively. When the rate returns to 0.1 C, the first discharge specific capacity is only 181.2 mAh / g, and the rate performance is poor. This shows that one-stage sintering makes the decomposition of the precursor and the formation rate of the crystal nucleus too fast, which leads to disordered crystal growth direction, easy formation of polycrystalline structure or secondary particles, and significant hindering of lithium ion diffusion by the crystal boundary, thereby reducing the rate performance.

[0096] Comparative Example 2

[0097] The difference between the present comparative example and Example 1 is only that in step (1), 2.776 g (30 mmol) of Ni 0.9 Co 0.05 Mn 0.05 (OH)2, 0.0487 g of H3BO3, and 0.0974 g of AlF3 are ball milled for 5 h at a mass ratio of the mixed powder to the ball mill beads of 1:5 and a mixing speed of 200 rpm until the mixed powder is uniformly mixed. The rest is the same as in Example 1.

[0098] Comparative Example 3

[0099] After 2.017 g (27 mmol) of nano-nickel oxide, 0.120 g (0.5 mmol) of nano-tricobalt tetroxide and 0.130 g (1.5 mmol) of nano-manganese dioxide are uniformly mixed with 1.322 g (31.50 mmol) of LiOH·H2O, two-stage microwave sintering is carried out under an oxygen atmosphere with a flow rate of 50 sccm: first, one-stage microwave sintering is carried out at a rate of 50 ℃ / min from room temperature to 400 ℃, and the temperature is kept for 60 min; then, two-stage microwave sintering is carried out at a rate of 50 ℃ / min from room temperature to 750 ℃, and the temperature is kept for 60 min; the furnace is cooled to room temperature; and grinding and crushing are carried out, to obtain a single-crystal ultrahigh-nickel positive electrode material LiNi 0.9 Co 0.05 Mn 0.05 O2.

[0100] Comparative Example 4

[0101] The difference between this comparative example and Example 1 is that in step (1), 0.0398 g of H3BO3 is not added; and in step (2), a single-doped single-crystal ultrahigh-nickel positive electrode material LiNi 0.90 Co 0.05 Mn 0.05 O2. The rest is the same as in Example 1.

[0102] Comparative Example 5

[0103] The difference between this comparative example and Example 1 is that in step (1), 0.0796 g of AlF3 is not added; and in step (2), a single-doped single-crystal ultrahigh-nickel positive electrode material LiNi 0.90 Co 0.05 Mn 0.05 O2. The rest is the same as in Example 1.

[0104] Preparation method of the positive electrode tab in Comparative Examples 2-5: the same as in Application Example 1.

[0105] Assembling of the button lithium ion battery in Comparative Examples 2-5: the same as in Application Example 1.

[0106] Battery test of Comparative Examples 2-5: the first charge-discharge specific capacity and the cycle performance test are the same as in Application Example 1; and the test results are shown in Table 1.

[0107] Table 1 Comparison table of the electrochemical performance of the batteries assembled from the electrode tabs prepared in Examples 1-5 and Comparative Examples 1-5 of the application

[0108]

[0109] As shown in Table 1, the first reversible discharge specific capacity of the battery assembled by the electrode pole piece of Example 1 to 5 of the present application is as high as 222.82 mAh / g at 0.1C rate, and the first coulombic efficiency is as high as 85.67%, while the first discharge specific capacity and the first coulombic efficiency of the battery assembled by the electrode pole piece of Comparative Example 1 to 5 of the present application are slightly reduced, because the electrochemical performance is mainly determined by the performance of the ultra-high nickel positive electrode material itself.

[0110] As shown in Table 1, Figure 4 The discharge capacity retention rate of the battery assembled by the electrode pole piece of Example 1 of the present application can still reach 83.15% after 200 cycles at 0.5C, and the cycle performance is stable, which indicates that the doping of boron and aluminum and the microwave two-stage sintering can inhibit the structure collapse and micro-crack of the positive electrode material, reduce the cation mixing degree, maintain the long-term stability of the layered structure, and thus improve the cycle stability; while the discharge capacity retention rates of the batteries assembled by the electrode pole pieces of Comparative Example 1 to 5 of the present application are all decreased, and the cycle stability is deteriorated, among which, the cycle stability of the material obtained by performing microwave sintering only once in Comparative Example 1 is deteriorated, which indicates that the rapid heating in the one-stage sintering leads to the disorder of Li + migration path, and Ni 2+ is difficult to orderly migrate back to the transition metal layer, and the degree of cation mixing is significantly increased, and Li + deintercalation in the cycle causes lattice distortion, accelerates particle cracking and capacity decay; in Comparative Example 2, the nano nickel-cobalt-manganese oxide material is replaced by a nickel-cobalt-manganese hydroxide precursor, firstly, the cycle stability of the obtained material is deteriorated, which indicates that the nano oxide has low porosity, high density and low degree of cation mixing compared with the hydroxide precursor, and the cycle stability is improved due to the reduction of side reactions, and secondly, the preparation process of the nickel-cobalt-manganese hydroxide precursor is complex, and the cost is significantly higher than that of the nano oxide material used in the present application; in Comparative Example 3, no boron and aluminum doping is performed, in Comparative Example 4, only aluminum doping is performed, and in Comparative Example 5, only boron doping is performed, and the cycle stability of the obtained materials is deteriorated to different degrees, which indicates that the doped Al 3+ can partially replace the transition metal site, stabilize the layered structure and inhibit the cation mixing, the doped B 3+ can control the surface structure or occupy the interstitial site, optimize the Li + diffusion kinetics, Al 3+ and B 3+ co-doping can combine the structural stability and surface / kinetics optimization ability, realize the synergistic effect, and improve the cycle stability of the battery.

[0111] In conclusion, the double-doped single crystal high-nickel positive electrode material obtained by the embodiments 1-5 of the application has high initial coulomb efficiency, excellent rate performance and cycle performance, which indicates that the double-doped high-nickel positive electrode material obtained by the method of the application through boron and aluminum doping and microwave two-stage sintering can inhibit lattice distortion and enhance structural stability, and the cycle stability and rate performance are greatly improved, which provides an innovative path for high safety and high energy density of power batteries.

Claims

1. A dual-doped single-crystal ultra-high nickel cathode material, characterized in that, It is mainly made by the following methods: (1) Nano nickel oxide or nano cobalt tetroxide and / or nano manganese dioxide are ball-milled and mixed evenly with boron source and aluminum source to obtain mixed powder; the mass ratio of the nano nickel oxide or nano cobalt tetroxide and / or nano manganese dioxide to the mass ratio of boron source and aluminum source is 94-99:1-6; the mass ratio of boron source to aluminum source is 1-4:1-4; (2) After the mixed powder obtained in step (1) is mixed evenly with the lithium source, it is subjected to two-stage microwave sintering in an oxidizing atmosphere, cooled to room temperature in the furnace, and then ground and pulverized to obtain a double-doped single crystal ultra-high nickel cathode material.

2. The dual-doped single-crystal ultra-high nickel cathode material according to claim 1, characterized in that: In step (1), the average particle size of the nano nickel oxide, nano cobalt tetroxide, and nano manganese dioxide is 30–100 nm; the molar ratio of nickel in the nano nickel oxide, cobalt in the nano cobalt tetroxide, and manganese in the nano manganese dioxide is 90–95:0–10:0–10; the boron source includes one or more of boric acid, boron oxide, or lithium borate; and the aluminum source includes one or more of aluminum fluoride, aluminum oxide, or lithium aluminate.

3. The dual-doped single-crystal ultra-high nickel cathode material according to claim 1 or 2, characterized in that: In step (1), the mass ratio of the mixed powder to the milling beads is 1:5 to 20, the mixing speed of the milling is 200 to 800 rpm, and the time is 5 to 20 h.

4. The dual-doped single-crystal ultra-high nickel cathode material according to claim 1 or 2, characterized in that: In step (2), the total molar ratio of nickel in nano nickel oxide, cobalt in nano cobalt tetroxide, and manganese in nano manganese dioxide to lithium in the lithium source is 1:1.03 to 1.20; the lithium source includes one or more of lithium hydroxide monohydrate, lithium carbonate, or lithium nitrate.

5. The dual-doped single-crystal ultra-high nickel cathode material according to claim 3, characterized in that: In step (2), the total molar ratio of nickel in nano nickel oxide, cobalt in nano cobalt tetroxide, and manganese in nano manganese dioxide to lithium in the lithium source is 1:1.03 to 1.20; the lithium source includes one or more of lithium hydroxide monohydrate, lithium carbonate, or lithium nitrate.

6. The dual-doped single-crystal ultra-high nickel cathode material according to claim 1 or 2, characterized in that: In step (2), the flow rate of the oxidizing atmosphere is 50-200 sccm; the oxidizing atmosphere includes oxygen and / or air; in the microwave sintering, the microwave output power is 200-2900W and the microwave frequency is 2.45GHz; the two-stage microwave sintering refers to: firstly, heating from room temperature to 400-600℃ at a rate of 50-100℃ / min and holding for 5-60 min to perform a first-stage microwave sintering, and then heating to 750-950℃ at a rate of 50-100℃ / min and holding for 5-60 min to perform a second-stage microwave sintering.

7. The dual-doped single-crystal ultra-high nickel cathode material according to claim 3, characterized in that: In step (2), the flow rate of the oxidizing atmosphere is 50-200 sccm; the oxidizing atmosphere includes oxygen and / or air; in the microwave sintering, the microwave output power is 200-2900W and the microwave frequency is 2.45GHz; the two-stage microwave sintering refers to: firstly, heating from room temperature to 400-600℃ at a rate of 50-100℃ / min and holding for 5-60 min to perform a first-stage microwave sintering, and then heating to 750-950℃ at a rate of 50-100℃ / min and holding for 5-60 min to perform a second-stage microwave sintering.

8. The dual-doped single-crystal ultra-high nickel cathode material according to claim 4, characterized in that: In step (2), the flow rate of the oxidizing atmosphere is 50-200 sccm; the oxidizing atmosphere includes oxygen and / or air; in the microwave sintering, the microwave output power is 200-2900W and the microwave frequency is 2.45GHz; the two-stage microwave sintering refers to: firstly, heating from room temperature to 400-600℃ at a rate of 50-100℃ / min and holding for 5-60 min to perform a first-stage microwave sintering, and then heating to 750-950℃ at a rate of 50-100℃ / min and holding for 5-60 min to perform a second-stage microwave sintering.

9. An application of the dual-doped single-crystal ultra-high nickel cathode material as described in any one of claims 1 to 8, characterized in that: The cathode sheet made of the double-doped single-crystal ultra-high nickel cathode material as described in any one of claims 1 to 8 is used in the field of lithium-ion batteries.

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