阅读说明：本技术 一种用混合酸液浸泡对氧化物粉体包覆无定形磷酸盐薄层的制备方法 (Preparation method for coating amorphous phosphate thin layer on oxide powder by soaking in mixed acid solution ) 是由 杨立山 赵双双 周君健 于 2021-09-16 设计创作，主要内容包括：本发明公开一种用混合酸液浸泡对氧化物粉体包覆无定形磷酸盐薄层的制备方法。具体操作方案为,先按(1-5000)μL:(0.01-50)g:(10-500)mL的比例将浓磷酸、添加剂与分散剂混合搅拌得混合酸液；再按1 g:(1-100)mL的固液比将氧化物粉体分散于混合酸液中,并定温(0-80°C)搅拌一段时间(0.5-6 h)得浆料；最后把浆料抽滤或离心收集粉体,水和乙醇洗涤2到5次,干燥即得到磷酸盐包覆好的氧化物粉体。本发明通过以磷酸为磷源,利用一步法表面生长,实现原位包覆,形成厚度可控的纳米无定形磷酸盐包覆层,制备得到磷酸盐包覆的氧化物材料。加大了氧化物材料的耐热性、抗氧化性、结构稳定性,进一步提升了氧化物的性能。(The invention discloses a preparation method for coating an amorphous phosphate thin layer on oxide powder by soaking in mixed acid liquor. The specific operation scheme is that concentrated phosphoric acid, additive and dispersant are mixed and stirred according to the proportion of (1-5000) microliter, (0.01-50) g, (10-500) mL to obtain mixed acid liquor; dispersing the oxide powder into the mixed acid solution according to the solid-to-liquid ratio of 1g (1-100) mL, and stirring for a period of time (0.5-6 h) at a constant temperature (0-80 ℃) to obtain slurry; and finally, carrying out suction filtration or centrifugation on the slurry to collect powder, washing the powder for 2 to 5 times by using water and ethanol, and drying to obtain the phosphate coated oxide powder. According to the invention, phosphoric acid is used as a phosphorus source, and surface growth is carried out by a one-step method to realize in-situ coating, so that a nano amorphous phosphate coating layer with controllable thickness is formed, and the phosphate-coated oxide material is prepared. The heat resistance, oxidation resistance and structural stability of the oxide material are improved, and the performance of the oxide is further improved.)

1. A method for preparing an amorphous phosphate thin layer coated on oxide powder by soaking in mixed acid liquor is characterized by comprising the following steps: the method comprises the following steps:

firstly, measuring a certain amount of concentrated phosphoric acid (98 wt%) as liquid; weighing a certain amount of additive as a solid; mixing one or more of pure water, ethanol, ethylene glycol and glycerol to obtain dispersant; mixing concentrated phosphoric acid, additive and dispersant according to the proportion of (1-5000) microliter (0.01-50) g (10-500) mL, and stirring to obtain mixed acid liquid;

dispersing the oxide powder into the mixed acid solution according to the solid-to-liquid ratio of 1g (1-100) mL, and stirring for a period of time (0.5-6 h) at a constant temperature (0-80 ℃) to obtain slurry;

thirdly, the slurry is filtered or centrifuged to collect powder, and the powder is washed with water and ethanol for 2 to 5 times and dried to obtain amorphous phosphate coated oxide powder.

2. The method for preparing the amorphous phosphate thin layer coated on the oxide powder by soaking in the mixed acid solution as claimed in claim 1, wherein:

in the step (i), the additive is one or more of polyvinylpyrrolidone (PVP), Sodium Alginate (SA), Cetyl Trimethyl Ammonium Bromide (CTAB), modified starch, glucose and fructose.

3. The method for preparing the amorphous phosphate thin layer coated on the oxide powder by soaking in the mixed acid solution as claimed in claim 1, wherein:

in the step (II), the oxide powder is aluminum oxide (Al)₂O₃) Silicon dioxide (SiO)₂) Magnesium oxide (MgO), manganese dioxide (MnO)₂) Zinc oxide (ZnO), titanium dioxide (TiO)₂) Ferroferric oxide (Fe)₃O₄) Transition metal oxides such as lithium manganese oxide and lithium nickel oxide; can also be lanthanum oxide (La)₂O₃) Cerium oxide (CeO)₂) Praseodymium oxide (Pr)₆O₁₁) Neodymium oxide (RbO)₂) Promethium oxide (Pm)₂O₃) Samarium oxide (Sm)₂O₃) Europium oxide (Eu)₂O₃) Oxides of rare earth metals; may also be lithium cobaltate(LiCoO₂) Lithium manganate (LiMn)₂O₄) An iso-ternary material; or iron phosphate (FePO)₄) Manganese (Mn) phosphate₃(PO₄)₂) Lithium iron phosphate (LiFePO)₄) Lithium manganese phosphate (LiMnPO)₄) And one or more of generalized oxides such as lithium manganese iron phosphate (LMFP).

4. The method for preparing the amorphous phosphate thin layer coated on the oxide powder by soaking in the mixed acid solution as claimed in claim 1, wherein: and the drying temperature in the third step is 50-100 ℃, and the drying environment is vacuum.

5. The method for preparing the amorphous phosphate thin layer coated on the oxide powder by soaking in the mixed acid solution as claimed in claim 1, wherein: the phosphate coating layer is a nano amorphous coating layer; the thickness of the coating layer is 1-100 nm.

6. The method for preparing the amorphous phosphate thin layer coated on the oxide powder by soaking in the mixed acid solution as claimed in claim 1, wherein the method comprises the following steps:

17.1. mu.L of concentrated phosphoric acid (98% wt) was weighed out, 0.3g of SA was weighed out and dispersed in 50 mL of ethanol, and 5 g of manganese sesquioxide (Mn) was added₂O₃) Mixing the powders, continuously stirring for 1.5 h at 25 ℃, washing for 2 times by deionized water and 1 time by ethanol after the reaction is finished, collecting the powders, and drying for 12 h in a vacuum drying oven at 60 ℃ to obtain the amorphous phosphate coated Mn with the thickness of about 3-15 nm₂O₃And (3) powder.

7. The method for preparing the amorphous phosphate thin layer coated on the oxide powder by soaking in the mixed acid solution as claimed in claim 1, wherein the method comprises the following steps:

respectively weighing 20.3 mu L of concentrated phosphoric acid (98 percent wt), weighing 1.0 g of modified starch, dispersing in 70 mL of ethylene glycol, and then mixing with 5 g of ternary material LiNi_0.8Co_0.15Al_0.05O₂(NCA), continuously stirring at 30 ℃ for reaction for 4 h, and after the reaction is finished, adding deionized waterWashing and ethanol washing are carried out for 3 times respectively, and drying is carried out for 12 hours in a vacuum drying oven at the temperature of 40 ℃ to obtain the amorphous phosphate coated NCA powder with the thickness of about 3-15 nm.

8. The method for preparing the amorphous phosphate thin layer coated on the oxide powder by soaking in the mixed acid solution as claimed in claim 1, wherein the method comprises the following steps:

respectively measuring 10.7 mu L of concentrated phosphoric acid (98 percent wt), weighing 0.1g of PVP, dispersing in 50 mL of acetone, and adding 5 g of lithium iron phosphate (LiFePO)₄) Continuously stirring the anode material at 15 ℃ for reacting for 2 hours, washing the anode material with deionized water and ethanol for 3 times respectively after the reaction is finished, drying the anode material in a vacuum drying oven at 80 ℃ for 5 hours, and drying the anode material in the amorphous phosphate coated LiFePO with the thickness of about 2-13 nm₄And (3) powder.

Technical Field

The invention relates to a coating modification method of amorphous phosphate with controllable thickness, in particular to a preparation method for coating amorphous phosphate with controllable thickness by one-step operation of oxide powder based on mixed acid.

Background

The functional oxide powder is widely applied in daily life, such as a catalyst applied in the chemical production process, an electrode material, an electro-catalytic material and a capacitor material applied in the field of energy storage, an anti-radiation material, a special refractory material, a corrosion-resistant material, a drying agent, an adsorbent and the like. Therefore, it plays an important role in the development of human socioeconomic performance. However, the oxide material has certain disadvantages in practical application, such as poor corrosion resistance and high-temperature oxidation resistance, and needs to be modified. The common modification method for oxide powder comprises the following steps: coating modification, doping modification, composite modification and the like. Wherein, the reaction conditions of doping modification are harsh and the reaction can not be accurately controlled; the composite modification operation is simple, but the modification result is not satisfactory; the coating modification is simple and convenient to operate, mild in condition and good in effect.

The coating modifier selected for the oxide is amorphous phosphate. Since phosphate has good chemical/electrochemical stability and wettability, it is used as a corrosion-resistant coating, a fire-resistant coating, a corrosion-resistant coating, a flame-retardant layer, and the like for photosensitive materials, wires, metals, ceramics, electrode powders, and the like. In addition, the lithium iron phosphate is a positive electrode material for power batteries and large-scale energy storage power stations, and shows excellent electrolyte wettability and stable electrochemical activity. There are many reports on crystalline phosphate coatings. For example, CN201610249845.3 coats montmorillonite with polyphosphate to synthesize a composite flame retardant, thereby improving the flame retardant performance and prolonging the service life of montmorillonite particles; CN201610664407.3 discloses a method for coating a lithium-rich manganese-based positive electrode material with a crystalline manganese phosphate, which improves the rate capability and cycle performance of a battery material; CN201811644905.7 adopts crystalline aluminum phosphate and aluminum oxide to clad the lithium titanate negative electrode in a composite manner, so that the high-temperature storage performance of the battery is improved. The research finds that the reported phosphate coating layers are polycrystalline phosphate materials which are obtained by a reaction path which is usually formed by precipitation reaction of water-soluble phosphate and metal ions and need subsequent high-temperature heat treatment. Therefore, there is no report of controllable growth of amorphous phosphate coating on the surface of oxide material by direct acid soaking.

The invention reports that oxide powder is directly soaked in phosphoric acid mixed solution for the first time, and an amorphous phosphate coated thin layer with controllable thickness components grows on the surface of the oxide powder through the chemical reaction of phosphoric acid and the surface layer of the oxide powder, so that the modified amorphous phosphate coated oxide composite material is finally obtained.

Disclosure of Invention

The technical problem solved by the invention is that phosphoric acid is used as a phosphorus source, surface growth is carried out by a one-step method, in-situ coating is realized, a nano amorphous phosphate coating layer with controllable thickness is formed, and the amorphous phosphate coating oxide material is prepared.

The technical scheme adopted by the invention for solving the technical problems is as follows: an amorphous phosphate coated oxide material characterized by: can be applied to industrial materials such as coatings, optical materials, flame retardant materials and the like; can be applied to battery materials, such as water-based batteries, organic batteries, air batteries and other battery materials; can also be applied to the technical fields of electrocatalytic materials, capacitor materials and other ultrathin coatings.

The preparation method for coating the amorphous phosphate thin layer on the oxide powder by soaking in the mixed acid solution comprises the following steps:

firstly, measuring a certain amount of concentrated phosphoric acid (98 wt%) as liquid; weighing a certain amount of additive as a solid; mixing one or more of pure water, ethanol, ethylene glycol and glycerol to obtain dispersant; mixing concentrated phosphoric acid, additive and dispersant according to the proportion of (1-5000) microliter (0.01-10) g (10-100) mL, and stirring to obtain mixed acid liquid;

dispersing oxide powder in the mixed acid solution according to the solid-to-liquid ratio of 1 g/(1-100) mL, and stirring for a period of time (0.5-6 h) at a constant temperature (0-80 ℃) to obtain slurry;

thirdly, the slurry is filtered or centrifuged to collect powder, and the powder is washed with water and ethanol for 2 to 5 times and dried to obtain amorphous phosphate coated oxide powder.

Further, the additive in the step is one or more of polyvinylpyrrolidone (PVP), Sodium Alginate (SA), Cetyl Trimethyl Ammonium Bromide (CTAB), modified starch, glucose and fructose.

Further, the oxide powder in the step is alumina (Al)₂O₃) Silicon dioxide (SiO)₂) Magnesium oxide (MgO), manganese dioxide (MnO)₂) Zinc oxide (ZnO), titanium dioxide (TiO)₂) Ferroferric oxide (Fe)₃O₄) Transition metal oxides such as lithium manganese oxide and lithium nickel oxide; can also be lanthanum oxide (La)₂O₃) Cerium oxide (CeO)₂) Praseodymium oxide (Pr)₆O₁₁) Neodymium oxide (RbO)₂) Promethium oxide (Pm)₂O₃) Samarium oxide (Sm)₂O₃) Europium oxide (Eu)₂O₃) Oxides of rare earth metals; may be lithium cobaltate (LiCoO)₂) Lithium manganate (LiMn)₂O₄) An iso-ternary material; or iron phosphate (FePO)₄) Manganese (Mn) phosphate₃(PO₄)₂) Lithium iron phosphate (II)LiFePO₄) Lithium manganese phosphate (LiMnPO)₄) And one or more of generalized oxides such as lithium manganese iron phosphate (LMFP).

Further, the drying temperature in the step is 50-100 ℃, and the drying environment is vacuum.

The invention has the beneficial effects that: the amorphous phosphate coated oxide material is prepared by taking phosphoric acid as a phosphorus source and utilizing one-step surface growth to realize in-situ coating to form a nano amorphous phosphate coating layer with controllable thickness. The technical scheme has simple process and easy operation, and is beneficial to the large-scale application of the oxide material.

Drawings

FIG. 1 shows Mn used in the first embodiment of the present invention₂O₃SEM image of powder raw material.

FIG. 2 shows amorphous phosphate coated Mn as an example of the present invention₂O₃SEM image of powder sample.

FIG. 3 shows amorphous phosphate coated Mn as an example of the present invention₂O₃EDS-Mapping chart of powder sample.

FIG. 4 shows Mn as a medium for use in the first embodiment of the present invention₂O₃Powder raw material and amorphous phosphate coated Mn₂O₃And respectively preparing a circulation performance graph and a coulombic efficiency curve graph of the button cell prepared from the powder sample.

FIG. 5 is a TEM image of an NCA powder raw material in example two of the present invention.

FIG. 6 is a TEM image of an amorphous phosphate coated NCA powder sample in example two of the present invention.

FIG. 7 is an SEM image of an amorphous phosphate coated NCA powder sample of example two.

FIG. 8 is an EDS-Mapping chart of an amorphous phosphate coated NCA powder sample in example two of the present invention.

FIG. 9 is a P2P XPS plot of amorphous phosphate coated NCA powder samples according to example two of the present invention.

FIG. 10 is a Ni 2p XPS plot of amorphous phosphate coated NCA powder samples according to example two of the present invention.

FIG. 11 is a Raman spectrum of an NCA powder raw material and an amorphous phosphate-coated NCA powder sample used in example two of the present invention.

Fig. 12 is a graph showing the cycling performance of button cells prepared separately from the NCA powder raw material and the amorphous phosphate coated NCA powder sample in example two of the present invention.

FIG. 13 is a CV diagram of the NCA powder raw material in example two of the present invention.

FIG. 14 is a CV diagram of a sample of amorphous phosphate coated NCA powder of example two of the present invention.

Detailed Description

The invention is further illustrated by the following examples, which are carried out in particular by the following methods:

the invention discloses a preparation method for coating an amorphous phosphate thin layer on oxide powder by soaking in mixed acid liquor. The specific operation scheme is that concentrated phosphoric acid, additive and dispersant are mixed and stirred according to the proportion of (1-5000) microliter, (0.01-50) g, (10-500) mL to obtain mixed acid liquor; dispersing the oxide powder into the mixed acid solution according to the solid-to-liquid ratio of 1g (1-100) mL, and stirring for a period of time (30 min-6 h) at a constant temperature (0-80 ℃) to obtain slurry; and (3) carrying out suction filtration or centrifugation on the slurry to collect powder, washing the powder with water and ethanol for 2 to 5 times, and drying to obtain amorphous phosphate coated oxide powder.

The first embodiment is as follows:

17.1. mu.L of concentrated phosphoric acid (98% wt) was weighed out, 0.3g of SA was weighed out and dispersed in 50 mL of ethanol, and 5 g of manganese sesquioxide (Mn) was added₂O₃) Mixing the powders, continuously stirring for 1.5 h at 25 ℃, washing for 2 times by deionized water and 1 time by ethanol after the reaction is finished, collecting the powders, and drying for 12 h in a vacuum drying oven at 60 ℃ to obtain the amorphous phosphate coated Mn with the thickness of about 3-15 nm₂O₃And (3) powder.

Example two:

20.3 mul of concentrated phosphoric acid (98 percent wt) is weighed, 1.0 g of modified starch is weighed and dispersed in 70 mL of ethylene glycol, and then the modified starch and 5 g of ternary material LiNi are mixed_0.8Co_0.15Al_0.05O₂(NCA), continuously stirring at 30 ℃ for reaction for 4 h, washing with deionized water and ethanol after the reaction is finishedDrying for 12 h at 40 ℃ in a vacuum drying oven for 3 times to obtain amorphous phosphate coated NCA powder with the thickness of about 3-15 nm.

Example three:

30.5 mul of concentrated phosphoric acid (98 wt%) was weighed, 0.5 g of SA was weighed and dispersed in 100 mL of ethanol, and 5 g of manganese sesquioxide (Mn) was added₂O₃) Mixing the powders, continuously stirring for 1.5 h at 25 ℃, washing for 2 times by deionized water and 1 time by ethanol after the reaction is finished, collecting the powders, and drying for 12 h in a vacuum drying oven at 60 ℃ to obtain the amorphous phosphate coated Mn with the thickness of about 7-20 nm₂O₃And (3) powder.

Example four:

respectively weighing 30.5 mu L of concentrated phosphoric acid (98 percent wt), weighing 3.0 g of modified starch, dispersing in 100 mL of ethylene glycol, and then mixing with 5 g of ternary material LiNi_0.8Co_0.15Al_0.05O₂(NCA), continuously stirring at 30 ℃ for reaction for 4 h, washing by deionized water and ethanol for 3 times respectively after the reaction is finished, and drying in a vacuum drying oven at 40 ℃ for 12 h to obtain amorphous phosphate coated NCA powder with the thickness of about 7-20 nm.

Example five:

respectively measuring 10.7 mu L of concentrated phosphoric acid (98 percent wt), weighing 0.1g of PVP, dispersing in 50 mL of acetone, and adding 5 g of lithium iron phosphate (LiFePO)₄) Continuously stirring the anode material at 15 ℃ for reacting for 2 hours, washing the anode material with deionized water and ethanol for 3 times respectively after the reaction is finished, drying the anode material in a vacuum drying oven at 80 ℃ for 5 hours, and obtaining amorphous phosphate coated LiFePO with the thickness of about 2-13 nm₄And (3) powder.

Example six:

35.2. mu.L of concentrated phosphoric acid (98% wt) was weighed out, 0.3g of CTAB was weighed out and dispersed in 100 mL of acetone, and 5 g of lithium cobaltate (LiCoO) was charged₂) Continuously stirring the anode material at 15 ℃ for reaction for 2 hours, washing the anode material with deionized water and ethanol for 3 times respectively after the reaction is finished, drying the anode material in a vacuum drying oven at 80 ℃ for 5 hours, and obtaining amorphous phosphate coated LiCoO with the thickness of about 5-27 nm₂And (3) powder.