Acid-etching-assisted metal oxide-coated high-nickel ternary positive electrode material, preparation method and application thereof

Abstract

The application belongs to the field of electrochemical energy storage batteries, and particularly relates to an acid-etching-assisted metal oxide-coated high-nickel ternary positive electrode material and a preparation method and application thereof. 1‑x‑y Co x Mn y (OH)2 ternary precursor, a strong acid weak base salt and a high-molecular polymer are mixed and dissolved to obtain a high-molecular polymer-assisted strong acid weak base salt-coated ternary precursor, then the ternary precursor and a lithium source are uniformly mixed, and heat treatment is performed under an oxygen atmosphere to obtain the final acid-etching-assisted metal oxide-coated high-nickel ternary positive electrode material. The positive electrode material enables the high-molecular polymer to be uniformly adsorbed on the surface of the ternary material precursor, thereby promoting the uniform coating of the metal oxide on the surface of the high-nickel ternary positive electrode material, effectively blocking the direct contact of the high-nickel positive electrode material with electrolyte and the like and the side reactions thereof, and having better cycle performance and rate performance, and is expected to promote the industrialization application of the high-nickel ternary positive electrode material.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage batteries, specifically relating to an acid-etched metal oxide-coated high-nickel ternary cathode material, its preparation method, and its application. Background Technology

[0002] As global warming and environmental pollution caused by carbon emissions become increasingly severe, society's demand for renewable and clean energy is also growing. This demand has driven the widespread application of electrochemical energy storage devices in power conversion, storage, and use, covering fields such as electric vehicles, electronic products, smart grids, and large-scale energy storage. Therefore, the development of electrochemical energy storage devices is crucial for achieving sustainable development and reducing adverse environmental impacts. With continuous technological advancements and improvements, electrochemical energy storage devices are expected to become an important component of the future clean energy sector, driving energy transformation and building a green and low-carbon society.

[0003] Among various cathode materials, layered cathode material LiNi x Co y Mn 1-x-y O2 combines the advantages of LiNiO2, LiCoO2, and LiMnO2, making it a research hotspot in the field of lithium-ion batteries. x Co y Mn 1-x-y In O2 cathode materials, the three transition metals play different roles in crystal structure and electrochemical performance. Typically, Ni provides most of the reversible capacity, while Co provides good electronic conductivity and enhances the orderliness of the layered structure, thus improving rate performance and providing additional capacity. Mn stabilizes the local structure to achieve stable cycling performance. In the NCM family, LiNi... 0.8 Co 0.1 Mn 0.1 O2 (NCM811) is one of the most promising cathode materials today due to its high discharge capacity, moderate cycle performance, and low production cost, and has been gradually applied to electric and hybrid vehicles. However, problems such as Li / Ni cation misalignment, transition metal dissolution, surface residual lithium, and side reactions in NCM811 cathodes have hindered its large-scale application.

[0004] To address these challenges, scientists have improved material performance through surface modification, lattice doping, and the construction of core-shell structures. Coating, as a surface modification method, can increase the lithium-ion diffusion rate, suppress transition metal dissolution, and inhibit side reactions, thereby improving the electrochemical performance of LNCM811. Concentration gradient structural modification can effectively improve the interfacial stability and structural integrity of LNCM811, reduce side reactions, and suppress material volume changes. Ion doping is another structural modification method. By introducing other ions into the LNCM811 lattice, cation mixing and subsequent phase transitions are suppressed, lattice distortion and further microcrack formation are inhibited, and the material's cycling performance is improved.

[0005] Surface modification through coating materials is considered an efficient strategy to improve the electrochemical performance of NCM811 cathode materials. Surface coatings can effectively reduce the direct contact area between NCM811 and the electrolyte, prevent HF from corroding highly delithiated NCM811, alleviate transition metal dissolution, and suppress undesirable side reactions on the NCM811 surface, thereby improving cycle stability. Interfacial coatings can reduce the exposed area of ​​the material in air, thus reducing side reactions between high-nickel surfaces and H2O / CO2, and reducing the formation of LiOH / Li2CO3 impurities. Metal oxides, as a coating material, are low-cost and have good coating effects, making them a feasible solution to the aforementioned problems. However, they still have some shortcomings. Due to the limitations of metal oxides and high-nickel LiNi... 1-x-y Co x Mn y The weak binding energy between O2 cathode materials makes it difficult to achieve a uniform and complete coating of the entire particle surface with a small amount of coating. If the coating is too thin, it may gradually detach during charging and discharging, losing its coating effect. If the coating is too thick, the coating itself, which is not an active material, may actually reduce the specific capacity of the material. However, due to its good coating effect, metal oxides still have significant advantages among coating materials. Therefore, how to achieve a uniform coating effect in high-nickel LiNi... 1-x- y Co x Mn y Constructing a uniform and appropriate coating layer on the O2 surface remains a challenge in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an acid-etched metal oxide-coated high-nickel ternary cathode material, its preparation method, and its application. Specifically, the following technical solution is adopted:

[0007] In the first aspect of the present invention, a preparation method of an acid-etching assisted metal oxide-coated high-nickel ternary cathode material is provided, including the following steps:

[0008] S1: Mix Ni 1-x-y Co x Mn y (OH)2 ternary precursor, a strong-acid weak-base salt, and a polymer are dissolved in water. After stirring evenly, suction filtration is carried out, and then drying is performed to obtain a polymer-assisted strong-acid weak-base salt-coated Ni 1-x-y Co x Mn y (OH)2 ternary precursor;

[0009] S2: Mix the Ni 1-x-y Co x Mn y (OH)2 ternary precursor obtained in S1 and a lithium source evenly, and then perform heat treatment in an oxygen atmosphere to finally obtain an acid-etching assisted metal oxide-coated high-nickel ternary cathode material;

[0010] The molecular formula of the acid-etching assisted metal oxide-coated high-nickel ternary cathode material is LiNi 1-x-y Co x Mn y O2, where 0 < x < 0.4, 0 < y < 0.4, and 1 - x - y ≥ 0.6; the dosage of the polymer is less than 10.0% of the mass fraction of the polymer-assisted strong-acid weak-base salt-coated Ni 1-x-y Co x Mn y (OH)2 ternary precursor obtained in S1; the dosage of the strong-acid weak-base salt is less than 10.0% of the mass fraction of the polymer-assisted strong-acid weak-base salt-coated Ni 1-x-y Co x Mn y (OH)2 ternary precursor obtained in S1; the mass fraction of the metal oxide coating layer in the acid-etching assisted metal oxide-coated high-nickel ternary cathode material is less than 10.0%.

[0011] Aiming at the above existing technical problems, the present invention proposes a two-step preparation method. First, taking Ni 1-x-y Co x Mn y (OH)2 as the ternary precursor, by mixing and dissolving with a strong-acid weak-base salt and a polymer, a polymer-assisted strong-acid weak-base salt-coated Ni 1-x-y Co x Mn yA ternary precursor (OH)₂ is used, which is then mixed with a lithium source and subjected to heat treatment. A metal oxide coating layer is formed on the surface through chemical action, ultimately yielding acid-etched, metal oxide-coated LiNi. 1-x-y Co x Mn y O2 cathode material.

[0012] In step S1 above, the solution after hydrolysis of a strong acid and a weak base is weakly acidic, thus making Ni... 1-x-y Co x Mn y The active sites of the (OH)2 precursor are exposed, providing a fresh surface for the anchoring of metal ions. At the same time, due to the long chain structure of PVP, the carbonyl group can donate a pair of electrons to the metal cation, forming a complex bond between nitrogen and the metal cation in the five-membered nitrogen-containing heterocycle, which can effectively connect NCM811 and metal ions, achieving a uniform and continuous coating effect.

[0013] The acid-etched metal oxide-coated LiNi prepared by this invention 1-x-y Co x Mn y O2 cathode material, the preparation process utilizes H2 generated by the hydrolysis of strong acid and weak base salts. + Ions activate the inert surface of the ternary material precursor, and the fully exposed active sites allow for more uniform adsorption of polymer molecules onto the ternary material precursor surface, thereby promoting uniform coating of metal oxides on the surface of the high-nickel ternary cathode material. This uniform and dense metal oxide coating layer can effectively block high-nickel LiNi... 1-x-y Co x Mn y Direct contact between O2 cathode materials and electrolytes, and their side reactions, enhance the performance of high-nickel LiNi alloys. 1-x- y Co x Mn y Cyclic performance of O2 cathode materials.

[0014] In this invention, the amount of strong acid-weak base salt and polymer used in step S1 is limited to less than that of Ni coated with strong acid-weak base salt by polymer assistance obtained in S1. 1-x-y Co x Mn y The (OH)₂ ternary precursor has a mass fraction of 10.0%. This limitation is, in part, to achieve the above-described technical concept / principle and thus successfully prepare the acid-etched metal oxide-coated LiNi of this invention. 1-x-y Co x Mn yO2 cathode material; on the other hand, it is also because if the amount used is too high, it will destroy the structural stability of the material during the cycle, and if the amount used is too low, the acid etching effect will be not obvious.

[0015] As a further preferred embodiment, Ni in step S2 above 1-x-y Co x Mn y The ratio of (OH)₂ ternary precursor to lithium source is 1:1.05. Too high a lithium source concentration will reduce cycle stability, while too low a concentration will reduce the material's capacity.

[0016] As a further preferred embodiment, the lithium source is at least one of lithium hydroxide monohydrate, lithium carbonate, lithium nitrate, or lithium acetate. More preferably, the lithium source is lithium hydroxide monohydrate. High-nickel ternary cathodes typically use lithium hydroxide monohydrate because, for ordinary ternary cathodes (6-series and below), although lithium hydroxide has strong reactivity and a low reaction temperature, its lithium content fluctuates greatly and it is highly corrosive. Therefore, ordinary ternary cathodes usually use lithium carbonate as the lithium source. However, for high-nickel ternary cathodes (especially 8-series and above), the calcination temperature is usually low. If lithium carbonate is used as the lithium source, insufficient calcination temperature will lead to incomplete decomposition, excessive free lithium on the cathode material surface, and excessive alkalinity, affecting product performance.

[0017] As a further preferred embodiment, the aforementioned strong acid-weak base salt is one of magnesium nitrate, aluminum nitrate, zirconium nitrate, lanthanum nitrate, zinc nitrate, and calcium nitrate. The aforementioned polymer is one of PVP (polyvinylpyrrolidone) and PDA (p-phenylenediamine).

[0018] As a further preferred embodiment, the specific process for forming the metal oxide coating is as follows: first, the temperature is increased to 400℃-500℃ at a rate of 1℃ / min-5℃ / min, and held for 3 h-10 h; then, the temperature is increased to 700℃-800℃ at a rate of 1℃ / min-5℃ / min, and held for 10 h-20 h. Heating too quickly will reduce the uniformity of the material coating, while heating too slowly will increase time costs.

[0019] In a second aspect, based on the above-described preparation method, an acid-etched metal oxide-coated high-nickel ternary cathode material was prepared. This cathode material can be applied in the preparation of lithium-ion batteries. Based on this, the present invention proposes a battery cathode sheet, the preparation process of which includes the following steps: coating LiNi with an acid-etched metal oxide... 1-x-y Co x Mn y O2 cathode material, conductive agent, binder and solvent are mixed (LiNi coated with acid-etched metal oxide). 1-x-y Co x Mn yThe positive electrode material (O2), conductive agent, binder, and solvent are mixed in a preferred mass ratio of 8:1:1, coated onto a metal substrate, and then dried to obtain the battery positive electrode sheet. Using this positive electrode sheet as the positive electrode and a lithium metal sheet as the negative electrode, and after setting an electrolyte (selectively 1 M LiPF6 and EC / DMC / EMC in a volume ratio of 1:1:1) and a separator (selectively Celgard 2500 microporous membrane), a lithium-ion battery (which can be formed into a button cell) can be obtained.

[0020] The beneficial effects of the present invention are as follows: (1) In the acid-etched metal oxide-coated high-nickel ternary cathode material of the present invention, the H generated by the hydrolysis of strong acid and weak base salt is utilized. + Ions activate the inert surface of the ternary material precursor. Fully exposed active sites allow for more uniform adsorption of polymer molecules onto the ternary material precursor surface, thereby promoting uniform coating of metal oxides on the surface of the high-nickel ternary cathode material. This uniform and dense metal oxide coating layer effectively blocks high-nickel LiNi... 1-x-y Co x Mn y Direct contact between O2 cathode materials and electrolytes, and their side reactions, enhance the performance of high-nickel LiNi alloys. 1-x- y Co x Mn y Cyclic performance of O2 cathode materials.

[0021] (2) In the acid-etched metal oxide-coated high-nickel ternary cathode material of the present invention, a small amount of metal oxide will not affect the transport of lithium ions during the charging and discharging process, and can reduce the LiNi 1-x-y Co x Mn y The O2 cathode material is in direct contact with the electrolyte. Therefore, it interacts with the uncoated LiNi. 1-x-y Co x Mn y Compared to O2 cathode materials, LiNi coated with acid-etched metal oxide is... 1-x-y Co x Mn y O2 cathode materials have better cycle performance and rate performance, and are expected to promote the industrial application of high-nickel ternary cathode materials. Attached Figure Description

[0022] Figure 1 The diagram shown is a schematic representation of the reaction of this invention.

[0023] Figure 2 The image shows pure LiNi. 0.8 Co 0.1 Mn 0.1 LiNi coated with O2 and acid-etched assisted alumina0.8 Co 0.1 Mn 0.1 O2 cathode material and alumina-coated LiNi 0.8 Co 0.1 Mn 0.1 Cycling performance curve of O2 cathode material (without added polymer) at 2C;

[0024] Figure 3 The image shows pure LiNi. 0.8 Co 0.1 Mn 0.1 LiNi coated with O2 and acid-etched assisted alumina 0.8 Co 0.1 Mn 0.1 O2 cathode material and alumina-coated LiNi 0.8 Co 0.1 Mn 0.1 Cycling performance curve of O2 cathode material (without added polymer) at 5C;

[0025] Figure 4 The image shows pure LiNi. 0.8 Co 0.1 Mn 0.1 LiNi coated with O2 and acid-etched assisted alumina 0.8 Co 0.1 Mn 0.1 O2 and alumina-coated LiNi 0.8 Co 0.1 Mn 0.1 Cycle rate curve of O2 cathode material (without added polymer). Detailed Implementation

[0026] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0027] Example 1

[0028] A method for preparing a high-nickel ternary cathode material coated with an acid-etched metal oxide includes the following steps:

[0029] (1) Weigh out 3.00g of Ni 0.8 Co 0.1 Mn 0.1(OH)₂ ternary precursor, 0.03 g PVP (polyvinylpyrrolidone), and 0.4 g aluminum nitrate were dissolved in a beaker containing water and stirred for 2 hours. The resulting solution was then filtered and dried to obtain a powder (Ni oxide coated with acid-etched metal oxide). 0.8 Co 0.1 Mn 0.1 (OH)2 ternary precursor);

[0030] (2) Grind the powder obtained in step (1) and 1.40 g of lithium hydroxide monohydrate evenly in a mortar, place it in a corundum crucible, put it in a tube furnace filled with oxygen, heat it to 480°C at a rate of 5°C / min, hold it at that temperature for 5 h, then heat it to 750°C at the same rate of 5°C / min, hold it at that temperature for 15 h, and then cool it naturally to obtain LiNi coated with acid-etched alumina. 0.8 Co 0.1 Mn 0.1 O2 cathode material.

[0031] A button cell battery, the preparation method of which includes the following steps:

[0032] LiNi coated with acid-etched assisted alumina 0.8 Co 0.1 Mn 0.1 O2 cathode material, super-p conductive agent, and polyvinylidene fluoride binder were mixed with N-methyl-2-pyrrolidone in a mass ratio of 8:1:1 to form a homogeneous slurry. This slurry was then uniformly coated onto aluminum foil using a coating method. After drying, the slurry was punched into circular electrode sheets and vacuum-dried at 120°C for 12 hours. The prepared PVP (polyvinylpyrrolidone)-assisted alumina-coated LiNi... 0.8 Co 0.1 Mn 0.1 The positive electrode is made of O2, the negative electrode is lithium metal sheet, the electrolyte is 1MLiPF6 and EC / DMC / EMC (volume ratio 1:1:1), and the separator is Celgard 2500 microporous membrane. The cells are assembled into a button cell in a glove box.

[0033] Example 2

[0034] A method for preparing a high-nickel ternary cathode material coated with an acid-etched metal oxide includes the following steps:

[0035] (1) Weigh out 3.00g of Ni 0.8 Co 0.1 Mn 0.1 (OH)₂ ternary precursor, 0.03 g PVP (polyvinylpyrrolidone), and 0.4 g magnesium nitrate were dissolved in a beaker containing water and stirred for 2 hours. The resulting solution was then filtered and dried to obtain a powder (Ni oxide coated with acid-etched metal oxide).0.8 Co 0.1 Mn 0.1 (OH)2 ternary precursor);

[0036] (2) Grind the powder obtained in step (1) and 1.40 g of lithium hydroxide monohydrate evenly in a mortar, place it in a corundum crucible, put it in a tube furnace filled with oxygen, heat it to 480°C at a rate of 5°C / min, hold it at that temperature for 5 h, then heat it to 750°C at the same rate of 5°C / min, hold it at that temperature for 15 h, and then cool it naturally to obtain LiNi coated with magnesium oxide with acid etching assistance. 0.8 Co 0.1 Mn 0.1 O2 cathode material.

[0037] A button cell battery, the preparation method of which includes the following steps:

[0038] The prepared acid-etched magnesium oxide-coated LiNi 0.8 Co 0.1 Mn 0.1 O2 cathode material, super-p conductive agent, and polyvinylidene fluoride binder were mixed with N-methyl-2-pyrrolidone in a mass ratio of 8:1:1 to form a uniform slurry. This slurry was then uniformly coated onto aluminum foil using a coating method. After drying, the slurry was punched into circular electrode sheets and vacuum-dried at 120°C for 12 hours. The prepared PVP (polyvinylpyrrolidone)-assisted magnesium oxide-coated LiNi... 0.8 Co 0.1 Mn 0.1 The positive electrode is made of O2, the negative electrode is lithium metal sheet, the electrolyte is 1MLiPF6 and EC / DMC / EMC (volume ratio 1:1:1), and the separator is Celgard 2500 microporous membrane. The cells are assembled into a button cell in a glove box.

[0039] Example 3

[0040] (1) Weigh out 3.00g of Ni 0.8 Co 0.1 Mn 0.1 (OH)₂ ternary precursor, 0.03 g PVP (polyvinylpyrrolidone), and 0.4 g zirconium nitrate were dissolved in a beaker containing water and stirred for 2 hours. The resulting solution was then filtered and dried to obtain a powder (Ni oxide coated with acid-etched metal oxide). 0.8 Co 0.1 Mn 0.1 (OH)2 ternary precursor);

[0041] (2) Grind the powder obtained in step (1) and 1.40 g of lithium hydroxide monohydrate evenly in a mortar, place it in a corundum crucible, put it in a tube furnace filled with oxygen, heat it to 480°C at a rate of 5°C / min, hold it at that temperature for 5 h, then heat it to 750°C at the same rate of 5°C / min, hold it at that temperature for 15 h, and then cool it naturally to obtain acid-etched zirconia-coated LiNi. 0.8 Co 0.1 Mn 0.1 O2 cathode material.

[0042] A button cell battery, the preparation method of which includes the following steps:

[0043] The prepared acid-etched zirconia-coated LiNi 0.8 Co 0.1 Mn 0.1 O2 cathode material, super-p conductive agent, and polyvinylidene fluoride binder were mixed with N-methyl-2-pyrrolidone at a mass ratio of 8:1:1 to form a homogeneous slurry. This slurry was then uniformly coated onto aluminum foil using a coating method. After drying, the slurry was punched into circular electrode sheets and vacuum-dried at 120°C for 12 hours. The prepared PVP (polyvinylpyrrolidone)-assisted zirconium oxide-coated LiNi... 0.8 Co 0.1 Mn 0.1 The positive electrode is made of O2, the negative electrode is lithium metal sheet, the electrolyte is 1MLiPF6 and EC / DMC / EMC (volume ratio 1:1:1), and the separator is Celgard 2500 microporous membrane. The cells are assembled into a button cell in a glove box.

[0044] Example 4

[0045] (1) Weigh out 3.00g of Ni 0.8 Co 0.1 Mn 0.1 (OH)₂ ternary precursor, 0.03 g PDA (p-phenylenediamine), and 0.4 g zinc nitrate were dissolved in a beaker containing water and stirred for 2 hours. The resulting solution was then filtered and dried to obtain a powder (Ni oxide coated with acid-etched metal oxide). 0.8 Co 0.1 Mn 0.1 (OH)2 ternary precursor);

[0046] (2) Grind the powder obtained in step (1) and 1.40 g of lithium hydroxide monohydrate evenly in a mortar, place it in a corundum crucible, put it in a tube furnace filled with oxygen, heat it to 480°C at a rate of 5°C / min, hold it at that temperature for 5 h, then heat it to 750°C at the same rate of 5°C / min, hold it at that temperature for 15 h, and then cool it naturally to obtain LiNi coated with zinc oxide with acid etching assistance. 0.8 Co 0.1Mn 0.1 O2 cathode material.

[0047] A button cell battery, the preparation method of which includes the following steps:

[0048] The prepared acid-etched zinc oxide-coated LiNi 0.8 Co 0.1 Mn 0.1 O2 cathode material, super-p conductive agent, and polyvinylidene fluoride binder were mixed with N-methyl-2-pyrrolidone at a mass ratio of 8:1:1 to form a uniform slurry. This slurry was then uniformly coated onto aluminum foil using a coating method. After drying, the slurry was punched into circular electrode sheets and vacuum-dried at 120°C for 12 hours. The prepared PDA-assisted zinc oxide-coated LiNi... 0.8 Co 0.1 Mn 0.1 The positive electrode is made of O2, the negative electrode is lithium metal sheet, the electrolyte is 1M LiPF6 and EC / DMC / EMC (volume ratio 1:1:1), and the separator is Celgard 2500 microporous membrane. The cells are assembled into a button cell in a glove box.

[0049] Comparative Example 1

[0050] A method for preparing a high-nickel ternary cathode material includes the following steps:

[0051] Weigh out 3.00g of Ni. 0.8 Co 0.1 Mn 0.1 The (OH)₂ ternary precursor and 1.40 g of lithium hydroxide monohydrate were ground evenly in a mortar and placed in an alumina crucible. The crucible was then placed in a tube furnace filled with oxygen and heated to 480 °C at a rate of 5 °C / min, held for 5 h, and then heated to 750 °C at the same rate of 5 °C / min, held for 15 h, and allowed to cool naturally to obtain LiNi. 0.8 Co 0.1 Mn 0.1 O2 cathode material.

[0052] A button cell battery, the preparation method of which includes the following steps:

[0053] Prepared LiNi 0.8 Co 0.1 Mn 0.1 O2 cathode material, super-p conductive agent, and polyvinylidene fluoride binder were mixed with N-methyl-2-pyrrolidone at a mass ratio of 8:1:1 to form a uniform slurry. This slurry was then uniformly coated onto aluminum foil using a coating method. After drying, it was punched into a circular electrode sheet and vacuum-dried at 120℃ for 12 hours. The prepared LiNi... 0.8 Co 0.1 Mn 0.1The positive electrode is made of O2, the negative electrode is lithium metal sheet, the electrolyte is 1M LiPF6 and EC / DMC / EMC (volume ratio 1:1:1), and the separator is Celgard 2500 microporous membrane. The cells are assembled into a button cell in a glove box.

[0054] Figure 1 The diagram shown is a schematic representation of the reaction of the present invention. Figure 1 As can be seen from this, by utilizing the characteristic that the solution after the hydrolysis of a strong acid and a weak base is weakly acidic, Ni... 1-x-y Co x Mn y The active sites of the (OH)2 precursor are exposed, providing a fresh surface for the anchoring of metal ions. Due to the long chain structure of PVP, the carbonyl group can donate a pair of electrons to the metal cation. In the five-membered nitrogen-containing heterocycle, a complex bond is formed between nitrogen and the metal cation, which can effectively connect NCM811 and the metal ion, achieving a uniform and continuous coating effect.

[0055] Figure 2 The image shows pure LiNi. 0.8 Co 0.1 Mn 0.1 LiNi coated with O2 and acid-etched assisted alumina 0.8 Co 0.1 Mn 0.1 O2 cathode material and alumina-coated LiNi 0.8 Co 0.1 Mn 0.1 Cycling performance curves of O2 cathode material (without added polymer) at 2C; by Figure 2 It can be seen that at a current density of 2C, the PLAO@NCM811 sample has a discharge capacity of 177.63 mAh / g at the 100th cycle and 168.82 mAh / g at the 200th cycle, which is higher than that of the LAO@NCM811 sample (163.25 mAh / g at the 100th cycle and 148.95 mAh / g at the 200th cycle) and the bare NCM811 sample (124.63 mAh / g at the 100th cycle and 115.39 mAh / g at the 200th cycle).

[0056] Figure 3 The image shows pure LiNi. 0.8 Co 0.1 Mn 0.1 LiNi coated with O2 and acid-etched assisted alumina 0.8 Co 0.1 Mn 0.1 O2 cathode material and alumina-coated LiNi 0.8 Co 0.1Mn 0.1 Cycling performance curve of O2 cathode material (without added polymer) at 5C; by Figure 3 It can be seen that the PLAO@NCM811 sample, at a current of 5C, has a maximum discharge capacity of 168.49 mAh / g at the 100th cycle and a maximum discharge capacity of 158.27 mAh / g at the 200th cycle, which is higher than that of the LAO@NCM811 sample (138.15 mAh / g at the 100th cycle and 122.45 mAh / g at the 200th cycle) and the bare NCM811 sample (124.63 mAh / g at the 100th cycle and 80.44 mAh / g at the 200th cycle).

[0057] Figure 4 The image shows pure LiNi. 0.8 Co 0.1 Mn 0.1 O2 cathode material, LiNi coated with acid-etched assisted alumina 0.8 Co 0.1 Mn 0.1 O2 and alumina-coated LiNi 0.8 Co 0.1 Mn 0.1 O2 cathode material (without added polymer) in cycle rate curve; by Figure 4 As can be seen from the comparison of the rate performance of the three samples, the results show that PLAO@NCM811 has better overall capacity retention at all rates. This superior rate performance compared to the NCM811 sample confirms the presence of nickel-rich LiNi. 0.8 Co 0.1 Mn 0.1 O2 has high electrochemical activity and utilization rate.

[0058] Although the description of the invention has been quite detailed and particularly of several described embodiments, it is not intended to limit it to any of these details or embodiments or any particular embodiment, but should be considered as providing a broad possible interpretation of the claims by referring to the appended claims and taking into account the prior art, thereby effectively covering the intended scope of the invention. Furthermore, the invention has been described above with respect to embodiments foreseeable by the inventors in order to provide a useful description, and non-substantial modifications to the invention that have not yet been foreseen may still represent equivalent modifications.

Claims

1. A method for preparing an acid-etched metal oxide-coated high-nickel ternary cathode material, characterized in that, Includes the following steps: S1: 3.00 g Ni 1-x-y Co x Mn y A ternary precursor of (OH)₂, 0.4 g of a strong acid-weak base salt, and 0.03 g of a polymer were mixed and dissolved in water. After thorough stirring, the mixture was filtered and dried to obtain Ni polymer-assisted strong acid-weak base salt coated with a polymer. 1-x-y Co x Mn y (OH)2 ternary precursor; S2: Mix the ternary precursor obtained in S1 with the lithium source, and then perform heat treatment in an oxygen atmosphere to finally obtain acid-etched metal oxide-coated high-nickel ternary cathode material. The molecular formula of the acid-etching assisted metal oxide-coated high-nickel ternary cathode material is LiNi 1-x-y Co x Mn y O2, where 0 < x < 0.4, 0 < y < 0.4, and 1 - x - y ≥ 0.6; the mass fraction of the metal oxide coating layer in the acid-etching assisted metal oxide-coated high-nickel ternary cathode material is less than 10.0%; In step S2, the ratio of ternary precursor to lithium source is 1:1.05; The specific process of the heat treatment is as follows: first, the temperature is raised to 400 ℃-500 ℃ at a rate of 1℃ / min-5 ℃ / min, and held for 3 h-10 h; then, the temperature is raised to 700 ℃-800 ℃ at a rate of 1 ℃ / min-5 ℃ / min, and held for 10 h-20 h. The strong acid-weak base salt is one of magnesium nitrate, aluminum nitrate, zirconium nitrate, lanthanum nitrate, and zinc nitrate. The polymer is polyvinylpyrrolidone.

2. The preparation method according to claim 1, characterized in that, The lithium source is at least one of lithium hydroxide monohydrate, lithium carbonate, lithium nitrate, or lithium acetate.

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