CN118299542A - A method for preparing positive electrode material by coating and modifying cerium-molybdenum composite oxide - Google Patents

A method for preparing positive electrode material by coating and modifying cerium-molybdenum composite oxide Download PDF

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CN118299542A
CN118299542A CN202410557765.9A CN202410557765A CN118299542A CN 118299542 A CN118299542 A CN 118299542A CN 202410557765 A CN202410557765 A CN 202410557765A CN 118299542 A CN118299542 A CN 118299542A
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cerium
positive electrode
composite oxide
molybdenum
electrode material
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徐辉
冯东
游椋洒
刘先帅
谢于辉
吴枫
朱远蹠
谢德龙
梅毅
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Kunming University of Science and Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes

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Abstract

本发明公开一种铈钼复合氧化物包覆改性制备正极材料的方法，将富镍正极材料与铈源粉末、钼源粉末加入到球磨机中，加入溶剂进行球磨处理，产物干燥后，在含氧气氛下进行煅烧，得到铈钼复合氧化物包覆改性的富镍正极材料；本发明表面形成的Ce‑Mo涂层可以抑制循环过程中电荷转移电阻的增大并稳定活性材料结构，同时Ce‑O\Mo‑O结构提供丰富的氧空位能够促进锂离子扩散，降低电荷转移阻力，同时高价态的Mo6+能够优先占据过渡金属层中的Ni位点，扩大了Li+扩散通道，提高了正极材料的Li+扩散速率，并改善了LIB的容量和倍率性能，本发明采用的铈钼复合氧化物包覆改性策略为其它低电导率电极材料的高性能化提供借鉴。The invention discloses a method for preparing a positive electrode material by coating and modifying a cerium-molybdenum composite oxide. The method comprises the following steps: adding a nickel-rich positive electrode material, a cerium source powder and a molybdenum source powder into a ball mill, adding a solvent for ball milling, and drying the product, and calcining the product in an oxygen-containing atmosphere to obtain a nickel-rich positive electrode material coated and modified by a cerium-molybdenum composite oxide. The Ce-Mo coating formed on the surface of the invention can inhibit the increase of charge transfer resistance during the cycle process and stabilize the structure of the active material. Meanwhile, the Ce-O\Mo-O structure provides abundant oxygen vacancies to promote lithium ion diffusion and reduce charge transfer resistance. Meanwhile, high-valent Mo 6+ can preferentially occupy Ni sites in a transition metal layer, thereby expanding Li + diffusion channels, increasing the Li + diffusion rate of the positive electrode material, and improving the capacity and rate performance of LIB. The cerium-molybdenum composite oxide coating and modification strategy adopted by the invention provides a reference for the high performance of other low-conductivity electrode materials.

Description

Method for preparing positive electrode material by coating and modifying cerium-molybdenum composite oxide
Technical Field
The invention belongs to the field of preparation of anode materials, and particularly relates to a method for preparing an anode material by coating and modifying a cerium-molybdenum composite oxide.
Background
With the increasing scarcity of traditional energy sources, it has become important to select a safer, more reliable energy alternative. In the modern electric age, lithium ion batteries are becoming important points of research due to their excellent portability, high energy density and stable cycle characteristics as a fast-growing high-efficiency energy storage technology, and are widely applied to industries such as portable electronic products, automobiles, aerospace and the like. Despite the great progress made by modern battery technology, the cruising ability and cost of batteries remain major obstacles to widespread use, which also highlights the relative differences between gasoline and electric vehicles.
The lithium ion battery has the advantages of high energy density, low cost, long cycle time and the like, and is widely applied to the fields of power supply and energy storage. The use time and the rapid charging function after the battery is fully charged are mainly considered when people select battery products, the high energy density means long endurance, the charging time is reduced by high-rate charging energy, and the equipment utilization rate is improved, so that the high energy density and high-rate charging and discharging battery are urgently needed to be developed. The high energy density requires the large capacity, the small mass and the small volume of the battery, and can meet the long-time use requirement; high rate charge and discharge requires that the battery be capable of rapid charge at high current without affecting stability and safety performance. The positive electrode material of the lithium ion battery comprises layered LiCoO 2、LiNixCoyMn(1-x-y)O2 (NCM) and LiNi xCoyAl(1-x-y)O2 (NCA), spinel LiMnO 4, olivine LiFePO 4 and the like, among them, ni-rich layered NCM materials (Ni. Gtoreq.0.6) have been widely studied for their superior specific capacity; The advantages of LiNi 0.6Co0.2Mn0.2O2 (NCM 622) positive electrode materials combined with the advantages of low nickel NCM materials with good stability (such as NCM111 and NCM 424) and high nickel positive electrode materials with high capacity (such as NCM 811) have become one of the most interesting alternative materials. However, NCM622 cathode materials still suffer from drawbacks, such as the nickel-rich materials have more labile Ni 3+, these ions tend to be converted to stable Ni 2+, since Ni 2+ (0.069 nm) has an ionic radius near the 3b site of the Li +(0.072nm),Ni2+ site that would occupy the 3a site of the Li + site, Thereby blocking Li + diffusion channels in the layered structure and increasing irreversible capacity. In addition, due to the high reactivity of Ni 4+ ions in the circulation process, the surface of the nickel-rich material is easier to react with electrolyte, so that the surface structure of the positive electrode material is poor, and the circulation stability is not facilitated. In addition, during charge and discharge, alkaline substances adhere to the surface of the nickel-rich material and react with the electrolyte to form a passivation film, which prevents ion diffusion of Li +, resulting in poor rate and cycle performance, especially at high cut-off voltage. In addition, liPF 6 in the electrolyte easily reacts with trace amounts of water on the surface of the cathode material, generating harmful HF, thereby corroding the cathode material. The surface coating can provide effective protection against electrolyte attack of the positive electrode material.
The electronic structure of the crystal and the nickel content change have great influence on the synthesis method, doping and coating modification of the NCM material, the NCM cathode material has the defects of cation mixing, phase change and the like in the charge-discharge process, the problems can be effectively relieved by doping and coating modification, the side reaction and the stable structure are restrained, and meanwhile, the conductivity, the cycle life, the rate capability, the storage capacity and the high-temperature high-pressure performance are improved, so that the fields continue to be the important points of research.
The phase change caused by the deintercalation of lithium ions easily occurs in the charge and discharge processes of the lithium ion battery, meanwhile, the phenomena of dissolution of transition metal and the like are easily caused by long-time circulation, the degradation phenomenon can be changed by adding a coating on the surface of the material to change the surface chemical property of the material, and the side reaction is reduced by isolating the interaction of electrolyte and a base material, so that the electrochemical performance of the lithium ion battery is improved. However, no good method is found at the present stage to achieve the object.
Disclosure of Invention
The invention provides a method for preparing a positive electrode material by coating and modifying a cerium-molybdenum composite oxide, which aims at the problems of rapid capacity attenuation and the like of the positive electrode material in the charge-discharge cycle process, adopts the cerium-molybdenum composite oxide to coat and modify the positive electrode material, and a Ce-Mo coating formed on the surface can inhibit the increase of charge transfer resistance and stabilize an active material structure in the cycle process, and the Ce-O/Mo-O structure provides rich Oxygen Vacancies (OVs) to promote the diffusion of lithium ions, reduce the charge transfer resistance and improve the capacity and multiplying power performance of LIB. The technical scheme of the invention is as follows:
a method for preparing a positive electrode material by coating and modifying cerium-molybdenum composite oxide comprises the following specific steps:
(1) Adding the positive electrode material, cerium source powder and molybdenum source powder into an agate ball milling tank, adding agate balls, adding a solvent, and grinding in a planetary ball mill to obtain composite slurry of the positive electrode material mixed by cerium and molybdenum ions;
(2) And (3) carrying out solid-liquid separation, washing and drying treatment on the composite slurry obtained in the step (1), taking out, and sintering to obtain the cerium-molybdenum composite oxide coated modified anode material.
The positive electrode material in the step (1) is one of LiNi0.8Co0.1Mn0.1O2、LiNi0.9Co0.05Mn0.05O2、LiNi0.6Co0.2Mn0.2O2、LiNi0.5Co0.2Mn0.3O2、LiNi0.8Co0.15Al0.05O2、LiNi0.815Co0.15Al0.035O2、LiCoO2、LiMnO2、LiFePO4、LiMn2O4、Li4Ti5O12、LiMn1.5Ni0.5O4、Li4Ti5O12 and the like; the proportion of the commercial single crystal positive electrode material is the same as that of the spherical positive electrode material, and only the morphology of the materials is different.
The cerium source powder of the transition metal in the step (1) mainly comprises one or more of Ce (NO 3)3·6H2 O and Ce (NH 4)2(NO3)6 and the like) mixed in any proportion.
The different molybdenum sources in the step (1) mainly comprise cerium source powder of transition metal (one or more of NH 4)6Mo7O24·4H2 O and NH 4)2MoO4 and the like) which are mixed in any proportion.
The molar ratio of cerium to molybdenum in the cerium source and the molybdenum source in the step (1) is 1:0.5-1:2.
The molar ratio of the positive electrode material in the step (1) to the sum of cerium and molybdenum in the cerium source and the molybdenum source is 1:0.03.
The solvent in the step (1) is universal solvent mainly alcohol or water.
The grinding rotating speed in the step (1) is 200-300 rpm, and the grinding time is 1.5-2.5 h.
The drying temperature in the step (2) is 60-110 ℃ and the drying time is 12-24 h.
In the step (2), the sintering temperature is 500-600 ℃, the heat preservation time is 6-9 h, and the sintering atmosphere is air or oxygen.
The invention has the beneficial effects that:
the Ce-Mo coating formed on the surface of the anode material prepared by coating and modifying the cerium molybdenum oxide can inhibit the increase of charge transfer resistance and stabilize the structure of an active material in the cyclic process, and the Ce-O\Mo-O structure provides rich Oxygen Vacancies (OVs) and can promote the diffusion of lithium ions, reduce the charge transfer resistance and improve the capacity and the multiplying power performance of LIB.
Detailed Description
In order to better embody the present invention, the following detailed description of the present invention is provided by way of specific examples, but the scope of the present invention is not limited to the above description.
Example 1
A method for preparing a positive electrode material by coating and modifying cerium-molybdenum composite oxide comprises the following specific steps:
(1) 0.0822g of ceric ammonium nitrate Ce (NH 4)2(NO3)6 and 0.0265g of ammonium paramolybdate tetrahydrate ((NH 4)6Mo7O24·4H2 O)) are weighed according to a molar ratio of 1:1, added into an agate ball milling tank, commercial spherical anode material LiNi 0.8Co0.1Mn0.1O2 powder is weighed according to a molar ratio of (Ce 4++Mo6+):LiNi0.8Co0.1Mn0.1O2 =0.03:1), added into the agate ball milling tank, added with solvent water 20mL, and ground for 2 hours in a planetary ball mill at 200rpm, so as to obtain composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 110 ℃ for 12 hours, preparing 3at% (Ce 4++Mo6+)@LiNi0.8Co0.1Mn0.1O2 material powder, heating to 500 ℃ in a tube furnace under an air atmosphere at a temperature rising gradient of 5 ℃/min, preserving heat for 9 hours, and cooling to room temperature to obtain the cerium-molybdenum composite oxide coated cathode material.
Example 2
A method for preparing a positive electrode material by coating and modifying cerium-molybdenum composite oxide comprises the following specific steps:
(1) Weighing 0.11g of cerium ammonium nitrate Ce (NH 4)2(NO3)6 and 0.0177g of ammonium paramolybdate tetrahydrate ((NH 4)6Mo7O24·4H2 O)) according to the molar ratio of 1:0.5, adding into an agate ball milling tank, weighing commercial spherical nickel-rich cathode material LiNi 0.8Co0.1Mn0.1O2 powder according to the molar ratio of (Ce 4++Mo6+):LiNi0.8Co0.1Mn0.1O2 =0.03:1), adding into the agate ball milling tank, adding 20mL of solvent water, and grinding for 2 hours at 200rpm in a planetary ball mill to obtain composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 110 ℃ for 18 hours to obtain 3at% (Ce 4++Mo6+)@LiNi0.8Co0.1Mn0.1O2 material powder, heating to 500 ℃ in a tube furnace under an air atmosphere at a temperature rising gradient of 5 ℃/min, preserving heat for 9 hours, and cooling to room temperature to obtain the cerium-molybdenum composite oxide coated cathode material.
Example 3
A method for preparing a positive electrode material by coating and modifying cerium-molybdenum composite oxide comprises the following specific steps:
(1) Weighing 0.055g of cerium ammonia nitrate Ce (NH 4)2(NO3)6 and 0.035g of ammonium paramolybdate tetrahydrate ((NH 4)6Mo7O24·4H2 O) according to a molar ratio of 1:2, adding into an agate ball milling tank, weighing commercial spherical nickel-rich cathode material LiNi 0.8Co0.1Mn0.1O2 powder according to a molar ratio of (Ce 4++Mo6+):LiNi0.8Co0.1Mn0.1O2 = 0.03:1), adding into the agate ball milling tank, adding 20mL of solvent water, and grinding for 2 hours at 200rpm in a planet ball mill to obtain composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 60 ℃ for 24 hours, preparing 3at% (Ce 4++Mo6+)@LiNi0.8Co0.1Mn0.1O2 material powder, heating to 600 ℃ in a tube furnace under an air atmosphere at a temperature rising gradient of 5 ℃/min, preserving heat for 9 hours, and cooling to room temperature to obtain the cerium-molybdenum composite oxide coated positive electrode material.
Example 4
A method for preparing LiFeO 4 anode material by coating and modifying cerium-molybdenum composite oxide comprises the following specific steps:
(1) 0.0822g of ceric ammonium nitrate Ce (NH 4)2(NO3)6 and 0.0265g of ammonium paramolybdate tetrahydrate ((NH 4)6Mo7O24·4H2 O)) were weighed according to a molar ratio of 1:1, added to an agate ball mill, commercial LiFePO 4 powder was weighed according to a molar ratio of (Ce 4++Mo6+):LiFePO4 =0.03:1, added to an agate ball mill, then added with 20mL of solvent water, and ground in a planetary ball mill at 200rpm for 2 hours to obtain a composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 110 ℃ for 12 hours, preparing 3at% (Ce 4++Mo6+)@LiFePO4 material powder, heating to 500 ℃ in a tube furnace under an air atmosphere at a temperature rising gradient of 5 ℃/min, preserving heat for 9 hours, and cooling to room temperature to obtain the cerium-molybdenum composite oxide coated cathode material.
Example 5
A method for preparing LiFeO 4 anode material by coating and modifying cerium-molybdenum composite oxide comprises the following specific steps:
(1) 0.0822g of ceric ammonium nitrate Ce (NH 4)2(NO3)6 and 0.0265g of ammonium paramolybdate tetrahydrate ((NH 4)6Mo7O24·4H2 O) were weighed according to a molar ratio of 1:1, added to an agate ball mill, commercial LiFePO 4 powder was weighed according to a molar ratio of (Ce 4++Mo6+):LiFePO4 =0.03:1, added to an agate ball mill, then added with 20mL of solvent water, and ground in a planetary ball mill at 300rpm for 1.5 hours to obtain a composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 60 ℃ for 24 hours, preparing 3at% (Ce 4++Mo6+)@LiFePO4 material powder, heating to 600 ℃ in a tube furnace under an air atmosphere at a temperature rising gradient of 5 ℃/min, preserving heat for 6 hours, and cooling to room temperature to obtain the cerium-molybdenum composite oxide coated cathode material.
Example 6
A method for preparing a positive electrode material by coating and modifying cerium-molybdenum composite oxide comprises the following specific steps:
(1) Weighing 0.055g of cerium ammonia nitrate Ce (NH 4)2(NO3)6 and 0.035g of ammonium paramolybdate tetrahydrate ((NH 4)6Mo7O24·4H2 O) according to a molar ratio of 1:2, adding into an agate ball milling tank, weighing commercial spherical nickel-rich cathode material LiNi 0.8Co0.1Mn0.1O2 powder according to a molar ratio of (Ce 4++Mo6+):LiNi0.8Co0.1Mn0.1O2 = 0.03:1), adding into the agate ball milling tank, adding 20mL of solvent water, and grinding for 2.5h at 250rpm in a planet ball mill to obtain composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 80 ℃ for 15 hours, preparing 3at% (Ce 4++Mo6+)@LiNi0.8Co0.1Mn0.1O2 material powder, heating to 550 ℃ in a tube furnace under an air atmosphere at a temperature rising gradient of 5 ℃/min, preserving heat for 7.5 hours, and cooling to room temperature to obtain the cerium-molybdenum composite oxide coated positive electrode material.
Comparative example 1
(1) 0.0822G of ceric ammonium nitrate Ce (NH 4)2(NO3)6 and 0.0265g of ammonium paramolybdate tetrahydrate ((NH 4)6Mo7O24·4H2 O)) are weighed according to a molar ratio of 1:1, added into an agate ball milling tank, and commercialized spherical nickel-rich cathode material LiNi 0.8Co0.1Mn0.1O2 powder is weighed according to a molar ratio of (Ce 4++Mo6+):LiNi0.8Co0.1Mn0.1O2 =0.05:1), added into the agate ball milling tank, added with solvent water 20mL, and ground for 2 hours in a planetary ball mill at 200rpm, so as to obtain composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 110 ℃ for 12 hours, preparing 3at% (Ce 4++Mo6+)@LiNi0.8Co0.1Mn0.1O2 material powder, heating to 500 ℃ in a tube furnace under an air atmosphere at a temperature rising gradient of 5 ℃/min, preserving heat for 9 hours, and cooling to room temperature to obtain the cerium-molybdenum composite oxide coated cathode material.
Comparative example 2
(1) 0.0822G of ceric ammonium nitrate Ce (NH 4)2(NO3)6 and 0.0265g of ammonium paramolybdate tetrahydrate ((NH 4)6Mo7O24·4H2 O)) are weighed according to a molar ratio of 1:1, added into an agate ball milling tank, and commercialized spherical nickel-rich cathode material LiNi 0.8Co0.1Mn0.1O2 powder is weighed according to a molar ratio of (Ce 4++Mo6+):LiNi0.8Co0.1Mn0.1O2 =0.03:1), added into the agate ball milling tank, added with solvent water 20mL, and ground for 2 hours in a planetary ball mill at 200rpm, so as to obtain composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 110 ℃ for 12 hours, preparing 3at% (Ce 4++Mo6+)@LiNi0.8Co0.1Mn0.1O2 material powder, heating to 600 ℃ in a tube furnace under an air atmosphere at a temperature rising gradient of 5 ℃/min, preserving heat for 12 hours, and cooling to room temperature to obtain the cerium-molybdenum composite oxide coated cathode material.
Comparative example 3
(1) 0.0822G of ceric ammonium nitrate Ce (NH 4)2(NO3)6 and 0.0265g of ammonium paramolybdate tetrahydrate ((NH 4)6Mo7O24·4H2 O) are weighed according to a molar ratio of 1:1 and added into an agate ball milling tank, (Ce 4++Mo6+):LiNi0.8Co0.1Mn0.1O2 =0.03:1), the commercial spherical nickel-rich positive electrode material LiNi 0.8Co0.1Mn0.1O2 powder is weighed according to a molar ratio and added into the agate ball milling tank, 20mL of solvent water is added, and the mixture is ground for 2 hours in a planetary ball mill at 200rpm, so as to obtain composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 110 ℃ for 12 hours, preparing 3at% (Ce 4++Mo6+)@LiNi0.8Co0.1Mn0.1O2 material powder, heating to 800 ℃ in a 5 ℃/min heating gradient in a tubular furnace under the air atmosphere, preserving heat for 9 hours, and cooling to room temperature to obtain the cerium-molybdenum composite oxide coated nickel-rich anode material.
Comparative example 4
(1) Weighing 6.24g of commercial spherical nickel-rich anode material LiNi 0.8Co0.1Mn0.1O2 powder and cerium ammonia nitrate Ce (NH 4)2(NO3)6 is added into an agate ball milling tank, then solvent water is added into 20mL, and grinding is carried out for 2 hours in a planetary ball mill at 200rpm to obtain composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 110 ℃ for 12 hours to obtain 3at% Ce 4+@LiNi0.8Co0.1Mn0.1O2 material powder, heating to 500 ℃ in a tube furnace under an air atmosphere at a temperature rising gradient of 5 ℃/min, preserving heat for 9 hours, and cooling to room temperature to obtain the Ce oxide coated anode material.
Comparative example 5
(1) 6.24G of commercial spherical nickel-rich cathode material LiNi 0.8Co0.1Mn0.1O2 powder and ammonium paramolybdate tetrahydrate ((NH 4)6Mo7O24·4H2 O)) are weighed according to the mol ratio of Mo 6+:LiNi0.8Co0.1Mn0.1O2 = 0.03:1 being 1:0.03, added into an agate ball milling tank, added with 20mL of solvent water, and ground for 2 hours at 200rpm in a planetary ball mill to obtain composite slurry;
(2) Filtering the composite slurry product obtained in the step (1), washing the solid with ethanol, transferring to an oven for drying, drying at 110 ℃ for 12 hours to obtain 3at% Mo 6+@LiNi0.8Co0.1Mn0.1O2 material powder, heating to 500 ℃ in a tube furnace under an air atmosphere at a temperature gradient of 5 ℃/min, preserving heat for 9 hours, and cooling to room temperature to obtain the Mo oxide coated positive electrode material.
The materials prepared in examples 1-6 and comparative examples 1-5 and commercial NCM811, commercial LiFePO 4 were used as positive electrodes, lithium metal was used as negative electrodes, a polypropylene film (Celgard 2400) was used as a separator, ethylene carbonate containing 1M lithium hexafluorophosphate was used as an electrolyte, and coin cells were assembled in a glove box filled with argon gas, the moisture content of the glove box was less than 0.01ppm, and the oxygen content was less than 0.01ppm; the positive electrode lithium ion NCM811 battery was tested for 50 cycle capacity retention at a charge and discharge rate of 1C at 2.8-4.3V, and LiFePO 4 battery at 2.5-4.2V, with the results shown in Table 1 below:
TABLE 1
As shown in examples 1-3, the first charge-discharge capacity of the NCM811 battery is 213.4mAh/g, 211.8mAh/g and 213.1mAh/g respectively under the current density of 1C, and compared with the commercial NCM811, the specific capacity of the modified cerium-molybdenum composite oxide can be improved, because Ce 4+ and Mo 6+ are doped into the NCM positive electrode material at high temperature to a certain extent, ni sites in the transition metal layer of the NCM811 are preferentially replaced, more Ni 2+ is formed, lithium-nickel mixed discharge is reduced, and poplar-taylor distortion is inhibited; the higher-valence Mo 6+ doping expands the lattice parameter of the NCM811, so that larger interlayer spacing exists between lattices of the NCM811, the intercalation and deintercalation of Li + are facilitated, the transmission performance of lithium ions is further improved, and the cerium-molybdenum composite oxide coating protects the NCM811 from being corroded by hydrofluoric acid (HF); from the comparison of example 1 and comparative examples 4-5, it was found that the effect of a single cerium or molybdenum oxide on the initial capacity and capacity retention of the NCM811 material was less pronounced than that of the cerium molybdenum composite oxide, because the catalytic effect provided by the cerium molybdenum composite oxide is effective to weaken the bandgap and increase the number of electronic states near the fermi level, which is advantageous for enhancing the thermodynamic and kinetic properties of the NCM811, and is superior to the oxide coating formed from a single element, which can form a stable interfacial film between the electrolyte and the active material, reducing side reactions; meanwhile, as shown in comparative examples 1-3, cerium-molybdenum composite oxides with different proportions still can bring about a larger difference in capacity retention rate, because Ce and Mo have a certain catalytic effect, wherein the surface coating and cerium with different proportions form lattice oxygen with different concentrations, so that the diffusion of lithium ions can be promoted, the charge transfer resistance can be reduced, and the capacity of a lithium ion battery can be improved; wherein a cerium molybdenum ratio of 1:1 is capable of providing more oxygen vacancies, which is also why example 1 possesses a higher initial capacity and capacity retention.
The main reason for the decrease in specific capacity of comparative example 1 compared with commercial NCM811 is that the coating formed is too thick, li + is difficult to be extracted and intercalated during charge and discharge, so that the decrease in discharge capacity in circulation is more obvious than that of other examples, after 50 cycles, the capacity retention rate is still higher than that of commercial NCM811, it is the protection effect of the cerium-molybdenum composite oxide coating on NCM811 against hydrofluoric acid (HF) corrosion, and it is found by comparing example 1 with comparative examples 2-3 that too high calcination temperature and too long holding time easily make the crystal lattice of the cerium-molybdenum composite oxide smaller, the crystallization performance of the material is poor, and the impurity phase is easily contained, the extraction and intercalation process of Li + is hindered, and the electrochemical performance influence on the material is also great.
In comparative examples 1 to 3, example 6, the cathode materials used in comparative examples 1 to 5 were commercial NCM811, and the cathode materials used in examples 4 to 5 were LiFePO 4, and as can be seen from the above table data, no matter whether the cathode materials were NCM811 or LiFePO 4, the initial discharge specific capacity and the cycle capacity retention rate of the coating materials were improved to some extent in comparison with the corresponding commercial cathode materials, indicating that the coating modification of the iron molybdate nano-sheet compound had a certain improvement effect on the properties of NCM811 and LiFePO 4.

Claims (9)

1. The method for preparing the anode material by coating and modifying the cerium-molybdenum composite oxide is characterized by comprising the following specific steps:
(1) Adding a solvent into the anode material, cerium source powder and molybdenum source powder, and grinding the mixture to obtain composite slurry;
(2) And (3) carrying out solid-liquid separation on the composite slurry obtained in the step (1), and washing, drying and calcining filter residues to obtain the cerium-molybdenum composite oxide coated modified anode material.
2. The method for preparing a positive electrode material by coating modification of a cerium-molybdenum composite oxide according to claim 1, wherein the positive electrode material in the step (1) is mixed in any proportion of one or more of LiNi0.8Co0.1Mn0.1O2、LiNi0.9Co0.05Mn0.05O2、LiNi0.6Co0.2Mn0.2O2、LiNi0.5Co0.2Mn0.3O2、LiNi0.8Co0.15Al0.05O2、LiNi0.815Co0.15Al0.035O2、LiCoO2、LiMnO2、LiFePO4、LiMn2O4、Li4Ti5O12、LiMn1.5Ni0.5O4、Li4Ti5O12.
3. The method for preparing a positive electrode material by coating modification of a cerium-molybdenum composite oxide according to claim 1, wherein the cerium source in step (1) is one or more of Ce (NO 3)3·6H2O、Ce(NH4)2(NO3)6) mixed in any proportion.
4. The method for preparing a positive electrode material by coating modification of a cerium-molybdenum composite oxide according to claim 1, wherein the molybdenum source in the step (1) is one or more of (NH 4)6Mo7O24·4H2O、(NH4)2MoO4) mixed in any proportion.
5. The method for preparing a positive electrode material by coating modification of a cerium-molybdenum composite oxide according to claim 1, wherein the molar ratio of cerium to molybdenum in the cerium source and the molybdenum source in the step (1) is 1:0.5-1:2.
6. The method for preparing a cathode material by coating modification of a cerium-molybdenum composite oxide according to claim 1, wherein the molar ratio of the cathode material in the step (1) to the sum of cerium and molybdenum in the cerium source and the molybdenum source is 1:0.03.
7. The method for preparing a positive electrode material by coating modification of a cerium-molybdenum composite oxide according to claim 1, wherein the grinding speed in the step (1) is 200-300 rpm, and the grinding time is 1.5-2.5 h.
8. The method for preparing a positive electrode material by coating modification of a cerium-molybdenum composite oxide according to claim 1, wherein the drying temperature in the step (2) is 60-110 ℃ and the drying time is 12-24 h.
9. The method for preparing a positive electrode material by coating modification of a cerium-molybdenum composite oxide according to claim 1, wherein the calcination temperature in the step (1) is 500-600 ℃, the time is 6-9 h, and the sintering atmosphere is air or oxygen.
CN202410557765.9A 2024-05-07 2024-05-07 A method for preparing positive electrode material by coating and modifying cerium-molybdenum composite oxide Pending CN118299542A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118943334A (en) * 2024-07-30 2024-11-12 昆明理工大学 Preparation method of a three-dimensional stacked structure iron molybdate nanosheet compound coated modified positive electrode material

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118943334A (en) * 2024-07-30 2024-11-12 昆明理工大学 Preparation method of a three-dimensional stacked structure iron molybdate nanosheet compound coated modified positive electrode material
CN118943334B (en) * 2024-07-30 2025-12-09 昆明理工大学 Preparation method of three-dimensional stacked structure iron molybdate nano sheet compound coated modified cathode material

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