A lithium battery negative electrode, a niobium-based negative electrode and a method for preparing the niobium-based negative electrode material

Abstract

The present invention discloses a lithium battery negative electrode, a niobium-based negative electrode, and a method for preparing the niobium-based negative electrode material. The negative electrode comprises a titanium niobate negative electrode material substrate and an artificial battery interface film coated on the substrate surface. The present invention increases the stability of the battery material by adding an interface film containing P, increases the ionic conductivity of the battery material by adding an interface film containing F, and increases both the stability and ionic conductivity of the battery material by adding an interface film containing B. The preparation method utilizes a coating uniformity additive to uniformly coat the artificial interface film on the surface of the niobium-based negative electrode. This allows the interface film containing P and B to stabilize the negative electrode cycle, while the interface film containing fluorine and B to enhance rate capability. This further enhances the performance of the niobium-based negative electrode, thereby improving product stability and facilitating industrial production. The artificial battery interface film coating the niobium-based negative electrode material is stably prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion battery materials, and in particular to a lithium battery negative electrode, a niobium-based negative electrode, and a method for preparing the niobium-based negative electrode material. Background Art

[0002] Lithium-ion secondary batteries, with their excellent performance, have become the ideal power source for the new generation of electric vehicles. Currently, the anode materials for lithium-ion secondary batteries commercialized on a large scale primarily utilize embedded reaction electrode structures, which can be broadly categorized into three types: graphite-based anodes, silicon anodes, lithium titanate anodes, and niobium-based anodes. In recent years, electric vehicles have seen a significant increase in demand for battery safety, fast charging, and energy density. Niobium-based anodes have a discharge voltage of approximately 1.6V, do not produce lithium dendrites, and have a theoretical discharge capacity of >360mAh / g, nearly double that of lithium titanate. They also offer excellent fast charging performance.

[0003] To achieve the cost-effectiveness of niobium-based batteries, the cycle life of niobium-based batteries must be long enough. Due to the high charge and discharge potential of niobium-based negative electrodes, it is difficult for traditional graphite-based electrolyte additives to form a film on the surface of titanium niobate negative electrodes. It is necessary to artificially construct a stable interface film on the surface of the negative electrode to increase the protection of the surface of niobium-based battery materials.

[0004] However, the cost of titanium niobate materials is currently high, so titanium niobate batteries have a high initial purchase cost, which restricts their large-scale application. If titanium niobate batteries have ultra-long cycle life, they will have a high cost-effectiveness throughout the entire life cycle of battery applications. However, the recyclability of titanium niobate materials is still unsatisfactory. Summary of the Invention

[0005] In view of this, one of the objectives of the present invention is to provide an active material with good stability, which can maintain excellent electrochemical performance at high rates and has high interface stability.

[0006] A second object of the present invention is to provide a method for preparing a negative electrode active material.

[0007] The third object of the present invention is to provide an application of a negative electrode active material.

[0008] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0009] A niobium-based negative electrode material, comprising a titanium niobate negative electrode material matrix and an artificial battery interface film coated on the surface of the matrix, wherein the chemical composition of the titanium niobate negative electrode material is: c Nb d O e, where 0<c≤1, 0<d≤1, 0<e≤1, M is at least one of Na, K, Al, Mg, Zn, Ni, Mn, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca, Nb, Ta, P, V, S, F, B, Si, Ba, Pb, In, Ga, Sb, Si, Bi and Sr, and the composition of the artificial battery interface film is: Li x B y P z O m F n , where 0≤x≤1, 0≤y≤1, 0≤z≤1, 0≤m≤2.2, 0≤n≤2.2, y, z and n cannot be 0 at the same time.

[0010] More preferably, the titanium niobate negative electrode material matrix has any of the following molecular formulas: Ni 0.166 Nb 0.333 O(NiNb2O6), Ti 0.142 Nb 0.286 O(TiNb2O7), Ti 0.069 Nb 0.345 O(Ti2Ni 10 O 29 ),Mg 0.023 Nb 0.391 O(Mg2Nb 34 O 87 ), Zn 0.023 Nb 0.391 O(Zn2Nb 34 O 87 )、Mo 0.030 Nb 0.364 O(MoNb 12 O 33 ), Ga 0.008 Nb 0.395 O(GaNb 49 O 124 ), Zr 0.16 1Nb 0.387 (ZrNb 24 O 62 ) and Ti 0.032 Nb 0.387 O(Ti2Nb 24 O 62 ) and their doped and coated derivatives.

[0011] More preferably, the component of the artificial battery interface film is any one of LiPO2F2, LiF, Li3BO3 and Li3PO4.

[0012] Further preferably, the artificial battery interface film is at least one of phosphoric acid, lithium fluoride, boric acid, lithium borate, lithium phosphate, lithium difluorophosphate, lithium dioxalatoborate, lithium difluorooxalatoborate and other compounds containing P, F and boron elements, and the mass of the artificial battery interface film is 0.1%-10% of the total mass.

[0013] A method for preparing a niobium-based negative electrode material comprises the following steps:

[0014] Step 1: wet-grinding the titanium source and the niobium source to obtain a first slurry with a target particle size.

[0015] Step 2: spraying and sintering the obtained first slurry to obtain a niobate matrix.

[0016] Step 3: Mix and grind the titanium niobate matrix, the artificial battery interface film and the coating uniformity additive to obtain a second slurry after wet mixing.

[0017] Step 4: After the wet-mixed second slurry is mixed and ground uniformly, the second slurry is spray-dried to obtain a spray-dried powder.

[0018] Step 5: calcining the powder, and sieving the calcined powder to obtain a niobium-based negative electrode material coated with an artificial battery interface film.

[0019] More preferably, the titanium source is one or more of titanium dioxide, titanium tetrachloride, titanium hydroxide, metatitanic acid, tetrabutyl titanate, titanium oxide sulfate, tetraethyl titanate, isopropyl titanate, titanium monoxide, and metallic titanium.

[0020] More preferably, the niobium source is one or more of niobium pentoxide, niobium oxide, niobium chloride, niobium oxalate, ammonium niobium oxalate, niobium dioxide and metallic niobium.

[0021] More preferably, the coating uniformity aid is at least one of carbon nanotubes, carboxymethyl cellulose, sodium carboxymethyl cellulose, sodium alginate, polyvinyl alcohol, polypropylene alcohol, citric acid, sucrose, glucose, pectin and polyethylene glycol, and the mass of the coating uniformity aid is 0.1%-15% of the total solid mass added.

[0022] A lithium battery negative electrode comprises at least two lithium battery negative electrode active materials selected from the group consisting of a separator, an electrolyte, a positive electrode, and a lithium supplement.

[0023] More preferably, a current collector is provided on the negative electrode of the lithium battery, and the current collector is loaded with the negative electrode active material of the lithium battery.

[0024] Compared with the prior art, the present invention has the following advantages: by adding a P interface film, the stability of the battery material can be increased; the interface film containing the F element can increase the ionic conductivity of the battery material; and the interface film containing the B element can simultaneously increase the stability and ionic conductivity of the battery material; through the preparation method, the artificial interface film agent is uniformly coated on the surface of the niobium-based negative electrode with the help of a coating uniformity auxiliary agent, so that the interface film containing the P element and the B element can stabilize the cycle of the negative electrode, and the interface film containing the fluorine element and the B element can improve the rate performance, further achieving the improvement of the niobium-based negative electrode performance, thereby improving the stability of the product, facilitating industrial production, and stably preparing an artificial battery interface film coating the niobium-based negative electrode material. DETAILED DESCRIPTION

[0025] A niobium-based negative electrode material, comprising a titanium niobate negative electrode material matrix and an artificial battery interface film coated on the surface of the matrix, wherein the chemical composition of the titanium niobate negative electrode material is: c Nb d O e , where 0<c≤1, 0<d≤1, 0<e≤1, M is at least one of Na, K, Al, Mg, Zn, Ni, Mn, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca, Nb, Ta, P, V, S, F, B, Si, Ba, Pb, In, Ga, Sb, Si, Bi and Sr, and the composition of the artificial battery interface film is: Li x B y P z O m F n , where 0≤x≤1, 0≤y≤1, 0≤z≤1, 0≤m≤2.2, 0≤n≤2.2, y, z and n cannot be 0 at the same time.

[0026] Specifically, the titanium niobate negative electrode material matrix has any of the following molecular formulas: Ni 0.17 Nb 0.33 O、Ti 0.14 Nb 0.29 O、Ti 0.07 Nb 0.34 O, Mg 0.02 Nb 0.39 O, Zn 0.02 Nb 0.39 O、Mo 0.03 Nb 0.36 O.Ga 0.01 Nb 0.4 O, Zr 0.16 Nb 0.39 O and Ti 0.03 Nb 0.39 O and its doped and coated derivatives.

[0027] Specifically, the component of the artificial battery interface film is any one of LiPO2F2, LiF, Li3BO3 and Li3PO4.

[0028] Specifically, the artificial battery interface film is at least one of hydrofluoric acid, phosphoric acid, lithium fluoride, boric acid, lithium borate, lithium phosphate, lithium difluorophosphate, lithium dioxalatoborate, lithium difluorooxalatoborate and other compounds containing P, F and boron elements, and the mass of the artificial battery interface film is 0.1%-10% of the total mass.

[0029] A method for preparing a niobium-based negative electrode material comprises the following steps:

[0030] Step 1: Wet-grind the titanium source and the niobium source to obtain a first slurry with a target particle size.

[0031] Step 2: spraying and sintering the obtained first slurry to obtain a niobate matrix.

[0032] Step 3: Mix and grind the titanium niobate matrix, the artificial battery interface film and the coating uniformity additive to obtain a second slurry after wet mixing.

[0033] Step 4: After the wet-mixed second slurry is mixed and ground uniformly, the second slurry is spray-dried to obtain a spray-dried powder.

[0034] Step 5: calcining the powder, and sieving the calcined powder to obtain a niobium-based negative electrode material coated with an artificial battery interface film.

[0035] Example 1

[0036] 36.3 g of niobium oxalate and 4.79 g of titanium dioxide were weighed and mixed evenly, and sintered at 1000 ° C to obtain sample 1 titanium niobate matrix negative electrode material. 10 g of titanium niobate negative electrode material, 1 g of hydroxymethyl cellulose and 0.2 g of LiPO2F2 were mixed and ground in N2, and the above mixture was sintered at 800 ° C for 5 h to obtain sample 2 artificial SEI-coated titanium niobate negative electrode material.

[0037] Example 2

[0038] Take 15.38g of niobium oxide and 4.52g of titanium dioxide material, mix them evenly, and sinter them at 1100 degrees Celsius for 12 hours to obtain sample 3 titanium niobate negative electrode matrix material. Evenly mix 10g of the above-mentioned titanium niobate negative electrode matrix material, 1g of glucose and 0.3g of lithium borate material, and then place the above mixture in a tube furnace and sinter at 900°C for 5 hours to finally obtain sample 4, artificial SEI-coated titanium niobate material.

[0039] Specifically, the titanium source is one or more of titanium dioxide, titanium tetrachloride, titanium hydroxide, metatitanic acid, tetrabutyl titanate, titanium oxide sulfate, tetraethyl titanate, isopropyl titanate, titanium monoxide, and metallic titanium.

[0040] Specifically, the niobium source is one or more of niobium pentoxide, niobium oxide, niobium chloride, niobium oxalate, ammonium niobium oxalate, niobium dioxide and metallic niobium.

[0041] Furthermore, the target particle size D50 of the milled titanium source and niobium source mixture is within the range of 20-2000 nm.

[0042] Specifically, the coating uniformity aid is at least one of carbon nanotubes, carboxymethyl cellulose, sodium carboxymethyl cellulose, sodium alginate, polyvinyl alcohol, polypropylene alcohol, citric acid, sucrose, glucose, pectin and polyethylene glycol, and the mass of the coating uniformity aid is 0.1%-15% of the total solid mass added.

[0043] By adding a P interface film, the stability of the battery material can be increased, the interface film containing the F element can increase the ionic conductivity of the battery material, and the interface film containing the B element can simultaneously increase the stability and ionic conductivity of the battery material; through the preparation method, the artificial interface film agent is evenly coated on the surface of the niobium-based negative electrode with the help of a coating uniformity auxiliary agent, so that the interface film containing the P element and the B element can stabilize the cycle of the negative electrode, and the interface film containing the fluorine element and the B element can improve the rate performance, further realizing the improvement of the niobium-based negative electrode performance, thereby improving the stability of the product, facilitating industrial production, and stably preparing an artificial battery interface film coated with niobium-based negative electrode materials.

[0044] Example 3

[0045] Follow the above steps to make a button battery

[0046] 1. Preparation and Pole

[0047] The negative electrode active material, carbon black as a conductive additive and polyvinylidene fluoride (PVDF) as a binder are dispersed in N-methylpyrrolidone (NMP) in a weight ratio of 80:10:10 and mixed evenly to prepare a uniform negative electrode slurry. The uniform negative electrode slurry is evenly coated on a copper foil current collector with a thickness of 10 μm and dried at 55°C to form a pole piece with a thickness of 100 μm. The pole piece is placed under a roller press (pressure is about 1 MPa×1.5 cm2), cut into discs with a diameter of φ14 mm, and then placed in a vacuum oven at 120°C for 6 hours. After natural cooling, it is taken out and placed in a glove box for use as a positive electrode piece.

[0048] 2. Assembling lithium-ion secondary batteries

[0049] First, in a glove box filled with an inert atmosphere, metallic lithium is used as the negative electrode of the battery. A three-layer PP / PE / PP film coated with aluminum oxide on both sides is placed between the positive and negative electrodes as a separator. A commonly used carbonate electrolyte is added dropwise. The positive electrode sheet prepared in the above steps is used as the positive electrode to assemble a button battery with model CR2032.

[0050] Battery rate cycle performance test:

[0051] The button cell prepared above was left at room temperature (25°C) for 10 hours, and then activated by charge and discharge. The charge and discharge cycle test of the button cell prepared above was then performed using a Blue Power battery charge and discharge tester. The details are as follows:

[0052] 1) At 25°C, cycle at 0.1C for 1 week, 0.33C for 5 weeks, 1C for 5 weeks, 5C for 9 weeks, and finally 1C for 30 weeks.

[0053] The discharge capacity and capacity retention rate of the button cells assembled with the negative electrode active materials of test samples 1-5 at 1C and 5C are shown in the following table:

[0054] Table 1

[0055]

[0056]

[0057] Low temperature rate performance test

[0058] Samples 1-4 were prepared into button batteries and activated using commercial electrolyte at a rate of 0.05C for three weeks at 25°C. They were discharged at a rate of 0.2C to 0.8V at -10°C and then discharged at a rate of 3C.

[0059] Table 2

[0060]

[0061] From the above Table 2, it can be concluded that the discharge capacity at low temperature and high rate is significantly improved.

[0062] Example 4

[0063] Take 15.38g of niobium oxide and 4.52g of titanium dioxide material, mix them evenly, and sinter them at 1100 degrees Celsius for 12 hours to obtain sample 3 titanium niobate negative electrode matrix material. 10g of the above-mentioned titanium niobate negative electrode matrix material, 0.2g of LiF material and 0.2g of carbon nanotube slurry are evenly mixed, and then the above mixture is placed in a box furnace and calcined at 750°C for 8 hours to obtain sample 5, artificial SEI-coated titanium niobate material.

[0064] A lithium battery negative electrode comprises at least two lithium battery negative electrode active materials selected from the group consisting of a separator, an electrolyte, a positive electrode, and a lithium supplement.

[0065] Specifically, a current collector is provided on the negative electrode of the lithium battery, and the current collector is loaded with the negative electrode active material of the lithium battery.

[0066] Furthermore, the electrolyte may be a commonly used liquid electrolyte or solid electrolyte.

[0067] The liquid electrolyte can be composed of an organic solvent and a lithium salt, and the organic solvent can be selected from one or more of ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, ethylene sulfite, propylene sulfite, diethyl sulfite, γ-butyrolactone, dimethyl sulfoxide, ethyl acetate, methyl acetate, tetrahydrofuran, dimethylmethane, 2-dimethyltetrahydrofuran, 1,2-dimethylethane, 1,3-dioxolane and diethylene glycol dimethyl ether.

[0068] The lithium salt can be selected from one or more of lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium trifluoromethylsulfonate, lithium difluorooxalatoborate, and lithium bis(oxalatoborate).

[0069] When a solid electrolyte is used, the particle size of the solid electrolyte particles may be 0.1 to 20 μm, specifically 0.5 to 10 μm.

[0070] The liquid electrolyte may contain electrolyte additives containing elements such as N, P, Si, B, F, S, or electrolyte additives containing carbonyl groups or benzene rings.

[0071] The lithium supplement is a substance containing lithium, such as lithium powder, lithium strips, lithium rods, organic lithium, inorganic lithium, including but not limited to Li6CoO4, Li2NiO2, Li2S, Li5FeO4, LiF, Li2O, Li2O2, Li3N and other substances.

[0072] The positive electrode contains LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2、LiMn2O4、Li(Ni 0.5 Mn 1.5 )O4, Li2FeSiO4, Li2MnSiO4, LiFePO4, LiFe x Mn 1-x PO4, as well as doped and coated derivatives of the aforementioned cathode materials.

[0073] Furthermore, the solid electrolyte can be Li3x La 2 / 3-x TiO3 (0≤x≤2 / 3) perovskite; with the general formula Li x M y NaSICON of (PO4)3 (1≤x≤3, 1≤y≤2, M is selected from one or more of Ge, Al, Ti, Ga, Zr, Fe and Nb) has a garnet-structured ceramic oxide; sulfides composed of Li2S-P2S5 and Li2S-Ge2S5; and solid electrolytes with other crystalline or amorphous structures.

[0074] For example, such as Li3N, LISICON (Lithium Super Ionic Conductor), Thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), one or more of oxide-based, sulfide-based, phosphate-based and polymer-based materials such as LiPON and PEO.

[0075] Among them, the ceramic oxide with garnet structure can be oxide Li5La3M2O 12 (M=Nb or Ta), Li6ALa2M2O 12 (A=Ca, Sr or Ba; M=Nb or Ta), Li 5.5 La3M 1.75 B 0.25 O 12 (M=Nb or Ta; B=In or Zr), Li7La3Zr2O 12 He Li 7.06 M3Y 0.06 Zr 1.94 O 12 (M=La, Nb or Ta).

[0076] This specific embodiment is merely an explanation of the invention and is not a limitation of the invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as they are within the scope of protection of the invention, they are protected by patent law.

Claims

1. A niobium-based negative electrode material, characterized in that: A niobate negative electrode material matrix and an artificial battery interface film coated on the surface of the matrix are used. The chemical composition of the niobate negative electrode material is: M c Nb d O e , wherein 0<c≤1, 0<d≤1, 0<e≤1, M is at least one of Na, K, Al, Mg, Zn, Ni, Mn, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca, Nb, Ta, P, V, S, F, B, Si, Ba, Pb, In, Ga, Sb, Bi and Sr; The artificial battery interface film is boric acid, lithium borate, lithium dioxalatoborate, or lithium difluorooxalatoborate, and the mass of the artificial battery interface film accounts for 0.1%-10% of the total mass; The niobate negative electrode material matrix has any of the following molecular formulas: Ni 0.166 Nb 0.333 O (NiNb2O6), Ti 0.142 Nb 0.286 O (TiNb2O7), Ti 0.069 Nb 0.345 O(Ti2Ni 10 O 29 ), Mg 0.023 Nb 0.391 O(Mg2Nb 34 O 87 )、Zn 0.023 Nb 0.391 O(Zn2Nb 34 O 87 )、Mo 0.030 Nb 0.364 O(MoNb 12 O 33 )、Ga 0.008 Nb 0.395 O(GaNb 49 O 124 )、Zr 0.16 1Nb 0.387 (ZrNb 24 O 62 ) and Ti 0.032 Nb 0.387 O(Ti2Nb 24 O 62 ) and their doped and coated derivatives.

2. A lithium battery negative electrode, characterized in that The invention comprises at least two of a separator, an electrolyte, a positive electrode, a lithium supplement agent and the niobium-based negative electrode material according to claim 1.

3. The lithium battery negative electrode according to claim 2, characterized in that A current collector is provided on the negative electrode of the lithium battery, and the niobium-based negative electrode material according to claim 1 is loaded on the current collector.

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