Lithium supplementing method of high-nickel ternary positive electrode material, product of lithium supplementing method and application of product

Abstract

The invention discloses a lithium supplementing method of a high-nickel ternary positive electrode material, a product and application thereof. The preparation method comprises the following steps: washing a high-nickel ternary positive electrode material in a thermal saturated lithium-rich salt aqueous solution, and gradually cooling to room temperature, so that lithium salt is supercooled on the surface of the high-nickel ternary positive electrode material to separate out and crystallize, a uniform lithium-rich salt crystal coating layer is formed, and high-nickel ternary positive electrode material particles with the lithium-rich salt crystal coating layer on the surface are obtained; and drying and annealing in an oxygen-containing atmosphere to obtain the lithium-supplemented high-nickel ternary positive electrode material. According to the method, washing and crystallization coating are performed through the thermal saturation lithium-rich saline solution, so that the dual effects of supplementing lithium and removing residual alkali impurities are simultaneously realized, the surface quality of the material is improved, and the cycle performance is improved. Compared with a traditional lithium supplementing method, the method overcomes the defects that a traditional lithium supplementing process is complex in step, the lithium supplementing amount is difficult to control, and residual alkali impurities on the surface of the material are difficult to remove at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery materials, and relates to a method for supplementing lithium to a high-nickel ternary cathode material, its products and applications. Background Art

[0002] In recent years, the rapid development of the new energy vehicle industry has put forward higher requirements for the comprehensive performance of power batteries, especially in terms of energy density, cycle life and safety. High-capacity anode materials (such as silicon-carbon anodes, nano-alloy anode materials) can significantly improve the energy density of batteries, but their low initial coulombic efficiency results in a large amount of active lithium being irreversibly consumed in the first cycle. Since the cathode material is the only lithium source in the lithium-ion battery, the consumption of a large amount of active lithium ions will severely limit the performance of the lithium-ion battery.

[0003] To solve the above problem of irreversible consumption of active lithium, the industry generally adopts lithium supplementation technology to make up for the loss of active lithium, thereby improving the overall capacity and cycle life of the battery. The lithium supplementation technology effectively alleviates the problem of insufficient actual capacity caused by the consumption of a large amount of lithium ions by new anode materials (such as silicon-carbon anodes, nano-alloy anodes) during the first charge and discharge process by supplementing active lithium into the battery system. It can not only significantly improve the energy density of the battery, but also extend the service life of the battery, meeting the demand of new energy vehicles for the high-capacity nature of high-performance power batteries. Currently, the actually applied lithium supplementation technologies mainly include three categories: electrolyte lithium supplementation, anode lithium supplementation, and cathode lithium supplementation, which are specifically as follows: For the electrolyte lithium supplementation technology, a decomposable lithium-containing compound (such as methyl lithium, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, etc.) is added to the electrolyte, which decomposes and releases lithium ions during the first charging of the battery to supplement the lithium loss. Chinese Patent CN202410729192.3 discloses an electrolyte lithium supplementation additive, the main component of which is lithium methanedisulfonate methyl ester. However, adding a lithium-containing compound to the electrolyte may cause a significant change in the concentration of lithium ions, resulting in poor voltage consistency of the lithium battery. In addition, the amount of lithium supplementation by such methods is small and it is difficult to meet the requirements of new anode materials for a higher amount of lithium supplementation.

[0004] For the anode lithium supplementation technology, a lithium source (such as metallic lithium powder, lithium alloy, etc.) is introduced on the surface or inside of the anode material (such as silicon-carbon anode, graphite anode), and lithium supplementation is carried out in the form of prelithiation. Chinese Patent CN109755502B reports a preparation method of a silicon-carbon anode lithium supplementation electrode sheet using metallic lithium powder, which improves the energy density of the lithium battery. Although the anode lithium supplementation effect is obvious and the amount of lithium supplementation is large, the process is complex. The anode material needs to be processed and used in an inert atmosphere throughout the process, with high process control difficulty and high production cost. In addition, since metallic lithium is introduced into the anode material in such a lithium supplementation method, lithium dendrites are likely to form during the reciprocating cycle, posing a high safety hazard.

[0005] The positive electrode lithium supplementation technology realizes the introduction of extra active lithium by introducing lithium-rich compounds (such as lithium-rich manganese-based materials, lithium-rich nickel cobalt manganese oxides, etc.) into the positive electrode material or introducing lithium salt compounds (such as Li 2 O, Li 6 CoO 4 , Li 5 FeO 4 , Li 2 DHBN, Li 2 C 2 O 4 , Li 2 NiO 2 , Li 8 ZrO 6 etc.) on the surface or inside of the positive electrode material. The disclosed patent CN202411653126.9 provides a lithium supplementation method of coating a layer of lithium supplementation compound on the surface of the positive electrode sheet, achieving the improvement of battery capacity and cycle life. However, this method requires changing the traditional electrode preparation process flow, and the lithium supplementation material layer prepared by the coating method is relatively thick, which may lead to an increase in interface impedance and puts forward high requirements for the electrode preparation process. Chinese patent CN202411620066.0 provides a preparation method and application of a positive electrode lithium supplement agent. By compounding lithium-rich lithium ferrate and an organic lithium supplement agent, the stability of lithium-rich lithium ferrate is improved, and the capacity and cycle performance of the secondary battery are enhanced. However, the decomposition product of the lithium supplement agent used in this method is LiFeO 2 , which does not have electrochemical activity. In the case of a large amount of lithium supplementation, the formed electrochemically inert phase will significantly increase the polarization phenomenon inside the electrode, resulting in uneven charge distribution and affecting the reaction kinetics performance. Chinese patent CN202411733729.X provides a preparation method of a positive electrode lithium supplementation capsule. By embedding the lithium supplement agent into the microcapsules of a polymer, the slow release of active lithium is realized. However, the microcapsules of the polymer used in this method are not conductive and will not decompose with the use of the battery, and may significantly reduce the electrochemical performance of the electrode material after being added. Summary of the Invention

[0006] The present invention aims to solve the deficiencies of the prior art and provides a lithium supplementation method, its product and application for a high-nickel ternary positive electrode material.

[0007] In the first aspect, the present invention provides a lithium supplementation treatment method and application for a high-nickel ternary positive electrode material, including the following steps: Step S1, preparing a high-nickel ternary positive electrode material by a solid-phase synthesis method.

[0008] Mix the high-nickel ternary positive electrode precursor and the lithium source evenly, then fully grind the mixture and sinter to obtain the high-nickel ternary positive electrode material.

[0009] Preferably, the chemical composition of the high-nickel ternary cathode precursor in step S1 is Ni x Co y Mn z (OH) 2 or Ni x Co y Al z (OH) 2 ; where 0.8 ≤ x < 1.0, y ≠ 0, z ≠ 0 and x + y + z = 1; Preferably, the lithium source in step S1 includes LiOH·H 2 O, Li 2 CO 3 , LiNO 3 one or more of; Preferably, the chemical formula of the high-nickel ternary cathode material in step S1 is LiNi x Co y Mn z O 2 or LiNi x Co y Al z O 2 ; where 0.8 ≤ x < 1.0, y ≠ 0, z ≠ 0 and x + y + z = 1; Preferably, the molar ratio of the high-nickel ternary cathode precursor to the lithium source in step S1 is 1:1.01 to 1:1.10; Preferably, the sintering conditions in step S1 are to pre-sinter for a period of time in an oxygen-containing atmosphere, and then heat to the target temperature at a certain heating rate and hold for a period of time; More preferably, the oxygen-containing atmosphere is pure oxygen or air; the pre-sintering temperature is 450 - 550 °C, and the time is 1 - 3 hours; the heating rate is 1 - 5 °C / min; the sintering temperature is 700 - 800 °C, and the holding time is 8 - 16 hours; Step S2: Under stirring conditions, add the lithium salt for lithium supplementation to distilled water and heat to medium-high temperature to form a hot saturated lithium-rich brine solution.

[0010] Preferably, the lithium salt for lithium supplementation in step S2 includes Li 2 C 2 O 4 (lithium oxalate), Li 2 C 4 O 4 (lithium squarate), Li 2 DHBN (3,4-dihydroxybenzonitrile dilithium) one or more of.

[0011] Preferably, the mass ratio of the lithium salt for lithium supplementation to distilled water in step S2 is 1:2 to 1:10; Preferably, the stirring rate in step S2 is 100 - 1000 rpm; Preferably, the temperature range for heating the solution to medium - high temperature in step S2 is 50 - 90 °C; Step S3: Under stirring conditions, the high - nickel ternary cathode material synthesized in step S1 is washed in the hot saturated lithium - rich brine solution prepared in step S2, and the temperature is gradually lowered to room temperature, so that the lithium salt supercools and precipitates crystals on the surface of the high - nickel ternary cathode material, forming a uniform lithium - rich salt crystal coating layer, and obtaining high - nickel ternary cathode material particles with a lithium - rich salt crystal coating layer on the surface.

[0012] Preferably, the solid - liquid mass ratio of the high - nickel ternary cathode material to the hot saturated lithium - rich brine solution in step S3 is 1:2 to 1:5; Preferably, the stirring rate in step S3 is 500 - 1500 rpm; Preferably, the cooling rate in step S3 is 0.2 - 5 °C / min; Step S4: The high - nickel ternary cathode material particles with a lithium - rich salt crystal coating layer obtained in step S3 are dried and annealed under an oxygen - containing atmosphere to obtain the lithium - supplemented high - nickel ternary cathode material.

[0013] Preferably, the drying temperature in step S4 is 80 - 150 °C, the drying time is 5 - 14 h, and the drying environment is vacuum or normal pressure; Preferably, the oxygen - containing atmosphere in step S4 is pure oxygen or air; Preferably, the annealing temperature in step S4 is 350 - 650 °C, the annealing heating rate is 1 - 5 °C / min, and the annealing time is 1 - 3 h.

[0014] In the second aspect, the present invention provides a lithium - supplemented high - nickel ternary cathode material prepared by the above - mentioned method.

[0015] In the third aspect, the present invention provides the application of the lithium - supplemented high - nickel ternary cathode material in the preparation of lithium - ion batteries.

[0016] The beneficial effects of the present invention are: The present invention aims to solve the deficiencies of the prior art and provides a method for lithium supplementation and its application for high-nickel ternary cathode materials. This method realizes the dual effects of lithium supplementation and removal of residual alkali impurities through washing and crystallization coating with a thermally saturated lithium-rich brine solution. The method for lithium supplementation of this cathode material has the advantages of simple process steps, the amount of lithium supplementation can be precisely controlled by the temperature of the lithium-rich salt saturated solution, and it is easy to scale up production. At the same time, it can effectively remove the residual alkali impurities on the surface of the high-nickel ternary cathode material, improve the surface quality of the material, and enhance the cycling performance. Compared with the traditional lithium supplementation method, the present invention overcomes the disadvantages of complex process steps, difficult control of the amount of lithium supplementation, and difficulty in simultaneously removing the residual alkali impurities on the material surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 XRD patterns of the high-nickel ternary cathode material before and after lithium supplementation treatment.

[0019] Figure 2 SEM images of the high-nickel ternary cathode material before and after lithium supplementation treatment.

[0020] Figure 3 TEM images of the high-nickel ternary cathode material before and after lithium supplementation treatment.

[0021] Figure 4 FTIR spectra of the high-nickel ternary cathode material before and after lithium supplementation treatment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention.

[0023] This embodiment provides a method for lithium supplementation treatment of high-nickel ternary cathode materials and its products and applications. The present invention realizes the dual effects of lithium supplementation and removal of residual alkali impurities (Li 2 O) through washing and crystallization coating with a thermally saturated lithium-rich salt solution. The method for lithium supplementation of this cathode material has the advantages of simple process, the amount of lithium supplementation can be precisely controlled by the temperature of the lithium salt saturated solution, and it is easy to scale up production. Its main technical solutions include the following steps: 1. Washing with a thermally saturated lithium-rich salt solution: Immerse the high-nickel ternary cathode material in a thermally saturated lithium-rich brine solution, and utilize the high solubility characteristics of the solution at high temperature to dissolve and remove the residual alkali impurities on the material surface, thereby reducing the surface alkalinity of the material.

[0024] 2. Cooling crystallization coating: Gradually reduce the temperature of the solution to cause the lithium salt to supercool and precipitate crystals on the surface of the material, forming a uniform lithium salt-rich crystal coating layer.

[0025] 3. Cyclic activation lithium supplementation: After assembling into a battery, apply a high voltage during the first charging process to release the active lithium ions in the coating material and compensate for the irreversible capacity loss.

[0026] This method for supplementing lithium in the cathode material has the advantages of simple process, controllable lithium supplementation amount, and easy large-scale production. At the same time, it can effectively remove the residual alkali on the surface of the high-nickel ternary cathode material, improve the surface quality of the material, and enhance the cycling performance.

[0027] Specifically, the method for supplementing lithium in the high-nickel ternary cathode material includes the following steps: Step 1: Prepare a high-nickel ternary cathode material (chemical formula: LiNi x Co y Mn z O 2 or LiNi x Co y Al z O 2 , 0.8 ≤ x < 1.0, y ≠ 0, z ≠ 0 and x + y + z = 1) by a solid-phase synthesis method.

[0028] The high-nickel ternary cathode material precursor (chemical formula: Ni x Co y Mn z (OH) 2 or Ni x Co y Al z (OH) 2 , 0.8 ≤ x < 1.0, 0.8 ≤ x < 1.0, y ≠ 0, z ≠ 0 and x + y + z = 1) is mixed with a lithium source in a molar ratio of 1:1.01 to 1:1.10. The mixture is thoroughly ground in a mortar, and then pre-sintered in an oxygen-containing atmosphere at a temperature of 450 - 550 °C for 1 - 3 hours, and subsequently heated to 700 - 800 °C at a heating rate of 1 - 5 °C / min and held for sintering for 8 - 16 hours.

[0029] Exemplarily, the lithium source includes one or more of LiOH·H 2 O, Li 2 CO 3 , LiNO 3 .

[0030] Exemplarily, the oxygen-containing atmosphere is pure oxygen or air.

[0031] Step 2: Add the lithium salt for lithium compensation to distilled water at a solid-liquid mass ratio of 1:2 to 1:10. While continuously stirring at a stirring rate of 100 - 1000 rpm, heat the solution to 50 - 90 °C to form a hot saturated lithium-rich brine solution.

[0032] Exemplarily, the lithium salt for lithium compensation includes Li 2 C 2 O 4 (lithium oxalate), Li 2 C 4 O 4 (lithium squarate), Li 2 DHBN (3,4-dihydroxybenzonitrile dilithium) or one or more of them.

[0033] Step 3: Add the high-nickel ternary cathode material synthesized in Step 1 to the hot saturated lithium-rich brine solution prepared in Step 2 at a solid-liquid mass ratio of 1:2 to 1:5. While maintaining the stirring rate at 500 - 1500 rpm and continuously stirring, gradually cool it to room temperature at a cooling rate of 0.2 - 5 °C / min, so that the lithium salt supercools and precipitates crystals on the surface of the high-nickel ternary cathode material to form a uniform lithium-rich salt crystal coating layer, and obtain high-nickel ternary cathode material particles with a lithium-rich salt crystal coating layer formed on the surface.

[0034] Step 4: Collect the high-nickel ternary cathode material particles in the solution obtained in Step 3 by methods such as centrifugal dehydration and suction filtration, dry them at 80 - 150 °C under normal pressure or vacuum for 5 - 14 hours, and then anneal them at 350 - 650 °C for 1 - 3 hours (1 - 5 °C / min) in an oxygen-containing atmosphere, etc., to obtain the high-nickel ternary cathode material after lithium compensation treatment.

[0035] Exemplarily, the oxygen-containing atmosphere is pure oxygen or air.

[0036] This embodiment also provides a lithium-compensated ternary high-nickel cathode material prepared by the above method, and the application of this lithium-compensated ternary high-nickel cathode material in the preparation of lithium-ion batteries.

[0037] The technical solutions of the present invention will be further explained and illustrated below in conjunction with several preferred embodiments, but the experimental conditions and set parameters therein should not be regarded as a limitation to the basic technical solutions of the present invention. And the protection scope of the present invention is not limited to the following embodiments.

[0038] Example 1-1, A method for lithium compensation of high-nickel ternary cathode material Step 1: Prepare a high-nickel ternary cathode material (chemical formula: LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) by solid-phase synthesis method: High-nickel ternary cathode material precursor (chemical formula Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 ) is mixed with a lithium source (LiOH·H 2 O) in a molar ratio of 1:1.05. The mixture is thoroughly ground in a mortar, then pre-sintered in a pure oxygen atmosphere at 480 °C for 2 hours, and subsequently heated to 750 °C at a heating rate of 2 °C / min and held for sintering for 10 hours.

[0039] Step 2: Lithium salt Li 2 C 2 O 4 for lithium supplementation is added to distilled water at a solid-liquid mass ratio of 1:8. While continuously stirring at a stirring rate of 400 rpm, the solution is heated to 60 °C to form a hot saturated salt solution.

[0040] Step 3: The high-nickel ternary cathode material synthesized in Step 1 is added to the prepared hot saturated lithium-rich salt solution at a solid-liquid mass ratio of 1:3. While maintaining a stirring rate of 1000 rpm and continuously stirring uniformly, the temperature is gradually lowered to room temperature at a cooling rate of 0.5 °C / min.

[0041] Step 4: The high-nickel ternary cathode material particles in the obtained solution are collected by means such as centrifugal dehydration and suction filtration, and the high-nickel ternary cathode material after lithium supplementation treatment is obtained through steps such as vacuum drying at 120 °C for 12 hours and annealing at 400 °C for 2 hours (2 °C / min) in a pure oxygen atmosphere. The addition amount of the lithium supplementation agent is 3.2 wt.% (determined by thermogravimetry).

[0042] Figure 1 are the XRD patterns of the high-nickel ternary cathode material before and after lithium supplementation treatment in Example 1-1. There is no obvious difference in the XRD patterns of the two, indicating that this lithium supplementation method does not damage the crystal structure of the ternary cathode material.

[0043] Figure 2 are the SEM images of the high-nickel ternary cathode material before and after lithium supplementation treatment in Example 1-1. By observing the SEM images, it can be clearly seen that there are a large number of residual alkali substances on the surface of the high-nickel ternary cathode material before treatment, while the crystalline residual alkali substances on the surface of the high-nickel ternary cathode material after treatment are significantly removed, and amorphous nanoparticles are attached, indicating that the present invention realizes the removal of residual alkali impurities on the material surface while achieving the uniform dispersion and coating of the lithium supplementation material.

[0044] Figure 3 are the TEM images of the high-nickel ternary cathode material before and after lithium supplementation treatment in Example 1-1. By observing the TEM images, it can be clearly observed that there is an obvious lithium salt coating layer on the surface of the high-nickel ternary cathode material before and after lithium supplementation treatment.

[0045] Figure 4 FTIR spectra of the high-nickel ternary cathode material before and after the lithium supplementation treatment in Example 1-1. By observing the FTIR spectra, it can be found that in the FTIR spectra of the high-nickel ternary cathode material prepared by this method, the vibration of the C-C bond belonging to Li 2 C 2 O 4 appears, and at the same time, the vibration peak intensities related to LiOH and Li 2 CO 3 are significantly weakened, indicating the successful preparation of the coating layer and the effective removal of surface residual alkali.

[0046] Example 1-2, A Lithium Supplementation Method for High-Nickel Ternary Cathode Material and Its Application in Lithium-Ion Batteries Mix the ternary cathode material before and after the lithium supplementation treatment in Example 1-1 with the binder PVDF and the conductive agent SuperP in a ratio of 90:5:5 wt.%, mix them with NMP to form a paste, and coat it on the surface of the aluminum foil. After vacuum drying at 120 °C for 12 hours, cut the coated aluminum foil into circular pieces with a diameter of 13 mm as the electrode sheets. Assemble the electrode sheets, metal lithium foil sheets, and electrolyte (EC:EMC:DMC = 1:1:1, LiPF 6 with a concentration of 1 M) into a CR2025 type coin cell in a glove box. At room temperature, perform constant current charge and discharge tests using a Neware battery test system.

[0047] In the potential range of 3-4.3 V and at a rate of 0.2 C, the initial discharge specific capacity before the lithium supplementation treatment is 201.5 mAh·g -1 , and the initial discharge specific capacity after the lithium supplementation treatment is 211.2 mAh·g -1 , and the lithium supplementation specific capacity is 9.7 mAh·g -1 . Subsequently, perform a cycle test on this material in the potential range of 3-4.3 V. At a rate of 1 C, the cycle capacity retention rate before the lithium supplementation treatment is 79.58% (200 cycles), and the cycle capacity retention rate after the lithium supplementation treatment is 86.97% (200 cycles), indicating that this lithium supplementation method can effectively improve the capacity density and cycle performance.

[0048] Example 2-1, A Lithium Supplementation Method for High-Nickel Ternary Cathode Material Step 1: Prepare a high-nickel ternary cathode material (chemical formula LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) by a solid-phase synthesis method: The high-nickel ternary cathode material precursor (chemical formula Ni 0.8 Co0.1 Mn 0.1 (OH) 2 (OH) is mixed with a lithium source (LiOH·H 2 ₂O) at a molar ratio of 1:1.04. The mixture is thoroughly ground in a mortar and then pre-sintered in a pure oxygen atmosphere at 450 °C for 2 hours, followed by heating to 730 °C at a heating rate of 2 °C / min and sintering for 10 hours.

[0049] Step 2: The lithium salt Li 2 ₂ 2 CO 4 ₃ for lithium supplementation is added to distilled water at a solid-liquid mass ratio of 1:6. While continuously stirring at a stirring rate of 400 rpm, the solution is heated to 70 °C to form a hot saturated salt solution.

[0050] Step 3: The high-nickel ternary cathode material synthesized in Step 1 is added to the prepared hot saturated salt solution at a solid-liquid mass ratio of 1:4. While maintaining a stirring rate of 1000 rpm and continuously stirring uniformly, the temperature is gradually lowered to room temperature at a cooling rate of 0.4 °C / min.

[0051] Step 4: The high-nickel ternary cathode material particles in the obtained solution are collected by means such as centrifugal dehydration and suction filtration. Through steps such as vacuum drying at 120 °C for 12 hours and annealing at 400 °C for 3 hours (2 °C / min) in a pure oxygen atmosphere, the high-nickel ternary cathode material after lithium supplementation treatment is obtained. The addition amount of the lithium supplement is 4.1 wt.% (determined by thermogravimetry).

[0052] Example 2-2, A method for lithium supplementation of high-nickel ternary cathode materials and their application in lithium-ion batteries The ternary cathode materials before and after lithium supplementation treatment in Example 2-1 are mixed with a binder PVDF and a conductive agent SuperP at a ratio of 90:5:5 wt.%. After mixing with NMP, it is made into a paste and coated on the surface of an aluminum foil. After vacuum drying at 120 °C for 12 hours, the coated aluminum foil is cut into circular pieces with a diameter of 13 mm as the electrode sheets. The electrode sheets, metallic lithium foil sheets, and electrolyte (EC: EMC: DMC = 1:1:1, LiPF 6 ₆ concentration is 1 M) are assembled into a CR2025 type coin cell in a glove box. At room temperature, a constant current charge-discharge test is carried out using a Neware battery test system.

[0053] In the potential range of 3-4.3 V and at a rate of 0.2 C, the initial discharge specific capacity after lithium supplementation treatment is 212.8 mAh·g -1 , and the lithium supplementation specific capacity is 11.3 mAh·g -1Subsequently, cyclic voltammetry tests were carried out on this material in the potential range of 3 - 4.3 V. At a rate of 1 C, the cyclic capacity retention rate of the material after lithium supplementation treatment was 87.63% (200 cycles), indicating that the lithium supplementation method of the present invention can effectively improve the capacity density and cyclic performance.

[0054] Example 3 - 1, A method for supplementing lithium to a high - nickel ternary cathode material Step 1: Prepare a high - nickel ternary cathode material (chemical formula: LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) by a solid - state synthesis method: The precursor of the high - nickel ternary cathode material (chemical formula: Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 ) and a lithium source (LiOH·H 2 O) are mixed at a molar ratio of 1:1.03. The mixture is thoroughly ground in a mortar, then pre - sintered in a pure oxygen atmosphere at 450 °C for 2 hours, and subsequently heated to 700 °C at a heating rate of 2 °C / min and sintered for 16 hours.

[0055] Step 2: Add lithium salt Li 2 C 2 O 4 to distilled water at a solid - liquid ratio of 1:4. While continuously stirring at a stirring rate of 400 rpm, the solution is heated to 80 °C to form a hot saturated salt solution.

[0056] Step 3: Add the high - nickel ternary cathode material synthesized in Step 1 to the prepared hot saturated salt solution at a solid - liquid mass ratio of 1:2. While maintaining a constant stirring rate of 1000 rpm, the temperature is gradually decreased to room temperature at a cooling rate of 1 °C / min.

[0057] Step 4: Collect the high - nickel ternary cathode material particles in the obtained solution by suction filtration, and obtain the high - nickel ternary cathode material after lithium supplementation treatment through steps such as vacuum drying at 120 °C for 12 hours and annealing at 400 °C in a pure oxygen atmosphere for 3 hours (2 °C / min). The addition amount of the lithium supplement is 5.5 wt.% (determined by thermogravimetry).

[0058] Example 3 - 2, A method for supplementing lithium to a high - nickel ternary cathode material and its application in a lithium - ion battery The ternary cathode material before and after the lithium supplementation treatment in Example 3-1 was mixed with the binder PVDF and the conductive agent SuperP at a ratio of 90:5:5 wt.%, and after mixing with NMP, it was made into a paste and coated on the surface of the aluminum foil. After vacuum drying at 120 °C for 12 hours, the coated aluminum foil was cut into circular pieces with a diameter of 13 mm as the electrode sheets. The electrode sheets, metallic lithium foil sheets, and electrolyte (EC:EMC:DMC = 1:1:1, LiPF 6 with a concentration of 1 M) were assembled into CR2025 coin cells in a glove box. At room temperature, constant current charge-discharge tests were carried out using a Neware battery test system.

[0059] In the potential range of 3-4.3 V and at a rate of 0.2 C, the initial discharge specific capacity after the lithium supplementation treatment was 214.2 mAh·g -1 , and the lithium supplementation specific capacity was 12.7 mAh·g -1 . Subsequently, cyclic tests of this material were carried out in the potential range of 3-4.3 V. At a rate of 1 C, the cyclic capacity retention rate after the lithium supplementation treatment was 88.54% (200 cycles), indicating that the lithium supplementation method of the present invention can effectively improve the capacity density and cyclic performance.

[0060] Example 4-1, A method for supplementing lithium to a high-nickel ternary cathode material Step 1: Prepare a high-nickel ternary cathode material (chemical formula LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) by a solid-phase synthesis method: The precursor of the high-nickel ternary cathode material (chemical formula Ni 0.85 Co 0.05 Mn 0.1 (OH) 2 ) and the lithium source (LiOH·H 2 O) were mixed at a molar ratio of 1:1.05. The mixture was thoroughly ground in a mortar, and then pre-sintered in a pure oxygen atmosphere at a temperature of 450 °C for 2 hours, and then heated to 730 °C at a heating rate of 2 °C / min and sintered for 10 hours.

[0061] Step 2: Add the lithium salt Li 2 DHBN to distilled water at a solid-liquid mass ratio of 1:10, and while continuously stirring at a stirring rate of 400 rpm, heat the solution to 60 °C to form a hot saturated salt solution.

[0062] Step 3: Add the high-nickel ternary cathode material synthesized in Step 1 into the prepared hot saturated salt solution at a solid-liquid mass ratio of 1:4. While maintaining a stirring rate of 1000 rpm and continuously stirring at a constant speed, gradually cool it to room temperature at a cooling rate of 0.4 °C / min.

[0063] Step 4: Collect the high-nickel ternary cathode material particles in the obtained solution by means of centrifugal dehydration, suction filtration, etc. Through steps such as vacuum drying at 120 °C for 12 hours and annealing at 400 °C for 3 hours (2 °C / min) in a pure oxygen atmosphere, the high-nickel ternary cathode material after lithium supplementation treatment is obtained. The addition amount of the lithium supplement agent is 2.7 wt.% (determined by thermogravimetry).

[0064] Example 4-2, A method for lithium supplementation of high-nickel ternary cathode materials and its application in lithium-ion batteries Mix the ternary cathode materials before and after lithium supplementation treatment in Example 4-1 with the binder PVDF and the conductive agent SuperP at a ratio of 90:5:5 wt.%. After mixing with NMP, make it into a paste and coat it on the surface of the aluminum foil. After vacuum drying at 120 °C for 12 hours, cut the coated aluminum foil into circular pieces with a diameter of 13 mm as the electrode sheets. Assemble the electrode sheets, metal lithium foil sheets and electrolyte (EC: EMC: DMC = 1:1:1, LiPF 6 The concentration is 1 M) into a CR2025 type button battery in a glove box. At room temperature, perform constant current charge and discharge tests using a Neware battery test system.

[0065] In the potential range of 3-4.3 V and at a rate of 0.2 C, the initial discharge specific capacity of the lithium-supplemented treatment is 208.9 mAh·g -1 , and the lithium supplementation specific capacity is 7.4 mAh·g -1 . Subsequently, perform cyclic tests on this material in the potential range of 3-4.3 V. At a rate of 1 C, the cyclic capacity retention rate after lithium supplementation treatment is 83.48% (200 cycles), indicating that this lithium supplementation method can effectively improve the capacity density and cyclic performance.

[0066] Example 5-1, A method for lithium supplementation of high-nickel ternary cathode materials Step 1: Prepare a high-nickel ternary cathode material (chemical formula LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) by solid-phase synthesis method: The high-nickel ternary cathode material precursor (chemical formula Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 ) and the lithium source (Li 2CO 3 Mix them in a molar ratio of 1:1.05. Grind the mixture thoroughly in a mortar, then pre-sinter it in a pure oxygen atmosphere at 450 °C for 2 hours, and subsequently heat it to 800 °C at a heating rate of 2 °C / min and sinter for 10 hours.

[0067] Step 2: Add the lithium salt Li 2 C 4 O 4 to distilled water at a solid-liquid mass ratio of 1:5, and while continuously stirring at a stirring rate of 400 rpm, heat the solution to 70 °C to form a hot saturated salt solution.

[0068] Step 3: Add the high-nickel ternary cathode material synthesized in Step 1 to the prepared hot saturated salt solution at a solid-liquid mass ratio of 1:4, and while continuously stirring at a constant stirring rate of 1000 rpm, gradually cool it to room temperature at a cooling rate of 1 °C / min.

[0069] Step 4: Collect the high-nickel ternary cathode material particles in the obtained solution by means of centrifugal dehydration, suction filtration, etc., and obtain the high-nickel ternary cathode material after lithium supplementation treatment through steps such as vacuum drying at 120 °C for 12 hours and annealing at 400 °C for 3 hours (2 °C / min) in a pure oxygen atmosphere. The addition amount of the lithium supplement is 5.1 wt.% (determined by thermogravimetry).

[0070] Example 5-2. A method for lithium supplementation of a high-nickel ternary cathode material and its application in a lithium-ion battery Mix the ternary cathode material before and after lithium supplementation treatment in Example 5-1 with the binder PVDF and the conductive agent SuperP in a ratio of 90:5:5 wt.%, mix them with NMP to form a paste and coat it on the surface of the aluminum foil. After vacuum drying at 120 °C for 12 hours, cut the coated aluminum foil into circular pieces with a diameter of 13 mm as the electrode sheets. Assemble the electrode sheets, metallic lithium foil sheets and the electrolyte (EC:EMC:DMC = 1:1:1, LiPF 6 with a concentration of 1 M) into a CR2025 type button battery in a glove box. At room temperature, perform constant current charge and discharge tests using a Neware battery test system.

[0071] In the potential range of 3-4.3 V and at a rate of 0.2 C, the initial discharge specific capacity after lithium supplementation treatment is 210.7 mAh·g -1 , and the lithium supplementation specific capacity is 9.2 mAh·g -1Subsequently, cyclic tests were carried out on this material in the potential range of 3 - 4.3 V. At a rate of 1 C, the cyclic capacity retention rate after lithium supplementation treatment was 85.25% (200 cycles), indicating that the lithium supplementation method of the present invention can effectively improve the capacity density and cyclic performance.

[0072] Comparative Example, Traditional Blending Lithium Supplementation Method for Ternary Cathode Materials and Its Application in Lithium - Ion Batteries Step 1: Prepare a high - nickel ternary cathode material (chemical formula LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) by solid - phase synthesis method: The precursor of the high - nickel ternary cathode material (chemical formula Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 ) and a lithium source (LiOH·H 2 O) are mixed at a molar ratio of 1:1.05. The mixture is thoroughly ground in a mortar, then pre - sintered in a pure oxygen atmosphere at 480 °C for 2 hours, and then heated to 750 °C at a heating rate of 2 °C / min and kept at this temperature for 10 hours for sintering.

[0073] Step 2: Blend and supplement lithium to the ternary cathode material prepared by solid - phase synthesis and lithium oxalate by ball - milling at a ratio of 96.8:3.2 wt.%. The lithium - supplemented ternary cathode material, binder PVDF, and conductive agent SuperP are mixed at a ratio of 90:5:5 wt.%, mixed with NMP to form a paste, and coated on the surface of aluminum foil. After vacuum - drying at 120 °C for 12 hours, the coated aluminum foil is cut into circular pieces with a diameter of 13 mm as the electrode sheet. The electrode sheet, metallic lithium foil, and electrolyte (EC:EMC:DMC = 1:1:1, LiPF 6 concentration is 1 M) are assembled into a CR2025 - type button battery in a glove box. At room temperature, constant - current charge - discharge tests are carried out using a Neware battery test system.

[0074] In the potential range of 3 - 4.3 V and at a rate of 0.2 C, the initial discharge specific capacity of the comparative example is 205.7 mAh·g -1 , and the lithium - supplemented specific capacity is 4.2 mAh·g -1 . Subsequently, cyclic tests were carried out on this material in the potential range of 3 - 4.3 V. At a rate of 1 C, the cyclic capacity retention rate of the comparative example is 78.53% (200 cycles). Therefore, the lithium supplementation method of the present invention can more effectively improve the capacity density and cyclic performance compared with the traditional blending lithium supplementation method.

[0075] Table 1

[0076] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A lithium supplementation treatment method for a high-nickel ternary positive electrode material, characterized in that: The method comprises the following steps: Step S1, preparing a high-nickel ternary positive electrode material by a solid phase synthesis method; The high-nickel ternary positive electrode precursor is mixed evenly with a lithium source, and then the mixture is fully ground and sintered to obtain a high-nickel ternary positive electrode material; Step S2, adding lithium salt for lithium supplementation into distilled water under stirring conditions, and heating to a medium-high temperature to form a hot saturated lithium-rich salt aqueous solution; Step S3, under stirring conditions, the high-nickel ternary positive electrode material synthesized in step S1 is placed in the hot saturated lithium-rich salt aqueous solution prepared in step S2 for washing, and the temperature is gradually lowered to room temperature, so that the lithium salt is supercooled and crystallized on the surface of the high-nickel ternary positive electrode material to form a uniform lithium-rich salt crystal coating layer, thereby obtaining high-nickel ternary positive electrode material particles with a lithium-rich salt crystal coating layer formed on the surface; The high-nickel ternary positive electrode material particles with a lithium-rich salt crystal coating layer formed on the surface obtained in step S4 and step S3 are dried and annealed in an oxygen-containing atmosphere to obtain the high-nickel ternary positive electrode material after lithium supplementation treatment.

2. The method according to claim 1, characterized in that: The chemical composition of the high nickel ternary positive electrode precursor in step S1 is Ni x Co y Mn z (OH)2 or Ni x Co y Al z (OH)2; the chemical formula of the high nickel ternary positive electrode material is LiNi x Co y Mn z O2 or LiNi x Co y Al z O2; wherein, 0.8≤x<1.0, y≠0, z≠0 and x+y+z=1.

3. The method according to claim 1, characterized in that: The lithium source in step S1 includes one or more of LiOH·H2O, Li2CO3, and LiNO3.

4. The method according to claim 1, characterized in that: The sintering conditions in step S1 are pre-sintering for a period of time in an oxygen-containing atmosphere, then heating to the target temperature at a certain heating rate, and keeping warm for a period of time; the pre-sintering temperature is 450~550°C, and the time is 1~3 hours; the heating rate is 1~5°C / min; the sintering temperature is 700~800°C, and the holding time is 8~16 hours.

5. The method according to claim 1, characterized in that: The lithium salt for lithium supplementation in step S2 includes one or more of Li2C2O4, Li2C4O4, and Li2DHBN.

6. The method according to claim 1, characterized in that: The mass ratio of the lithium salt for lithium supplementation to distilled water in step S2 is 1:2-1:10; the solution is heated to a medium-high temperature in the range of 50-90°C.

7. The method according to claim 1, characterized in that: In step S3, the mass ratio of the high-nickel ternary positive electrode material to the hot saturated lithium-rich salt aqueous solution is 1:2-1:5; and the cooling rate is 0.2-5°C / min.

8. The method according to claim 1, characterized in that: In step S4, the annealing temperature is 350-650°C, the annealing heating rate is 1-5°C / min, and the annealing time is 1-3 h.

9. A high-nickel ternary positive electrode material after lithium supplementation treatment, prepared by the method according to any one of claims 1 to 8.

10. Use of the high-nickel ternary positive electrode material after lithium supplementation treatment as claimed in claim 9 in the preparation of lithium-ion batteries.

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