CN1979929A - Lamina-structure lithium-contained composite metal oxide coated with carbon and use thereof - Google Patents

Abstract

The invention relates to a layered structure lithium-containing composite metal oxide coated with carbon on the surface, which is a composite material with a core-shell structure. The core material is lithium-containing composite metal oxide particles with a layered structure. A "shell" formed of coated carbon layers. The structural feature of the layered lithium-containing composite metal oxide as the core material is: in the direction perpendicular to the c-axis in the crystal structure, oxygen atomic layers, lithium atomic layers, and oxygen atomic layers are alternately arranged in sequence. , metal layer and oxygen atomic layer. Due to the greatly improved surface electron conductance and electrical contact of the composite material, the charge-discharge specific capacity and rate performance are further improved, the charge-discharge efficiency and cycle performance are also significantly improved, and the material is cheap and the preparation process is simple. The secondary lithium battery using the composite material as the positive electrode material has high energy density, good cycle performance, safety and reliability, especially good rate performance, and can be applied to various occasions.

Description

A layered structure lithium-containing composite metal oxide coated with carbon on the surface and its application

technical field

The invention belongs to the technical field of materials, and in particular relates to a layered structure lithium-containing composite metal oxide coated with carbon on the surface and its application in the manufacture of positive electrode materials for secondary lithium batteries with high energy density.

Background technique

At present, the positive electrode active materials of secondary lithium batteries mainly include layered structure LiCoO ₂ , LiNiO ₂ and _LiNix Co _2-x Mn _x O ₂ , LiMn ₂ O ₄ with spinel structure and LiFePO ₄ with olivine structure, etc. Among them, LiMn ₂ O ₄ with a spinel structure has a capacity of 110mAh/g, which is suitable for high-power batteries, and LiFePO ₄ with an olivine structure has a capacity of 150mAh/g, which has a lower density and poorer rate performance, but better safety. These two types of materials are not suitable for application in high energy density secondary lithium batteries.

Compounds with a layered structure are mainly used in high energy density secondary lithium batteries at present. Among them, the actual specific capacity of LiCoO ₂ is between 130-145mAh/g. It is the earliest positive electrode active material used in commercial secondary lithium batteries. It has stable performance and is easy to synthesize, and has been widely used. However, due to the high price of Co, it is difficult to reduce the cost of secondary lithium batteries using _LiCoO2 as the cathode material, and the lithium storage capacity of this material can no longer meet the current market requirements for high energy density secondary lithium battery cathode materials. Compared with LiCoO ₂ , the production cost of layered LiNiO ₂ is lower, but the synthesis of single-phase LiNiO ₂ is very difficult in the process, and the structure of LiNiO ₂ is not as stable as LiCoO ₂ , and the capacity is fast during charge and discharge. attenuation. On _this basis, _{currently invented} binary _LiNixMyO2 , _{LiCoxMyO2 , LiMnxMyO2} or _ternary materials _{LiNixCo2 -xMnxO2 , all} have _relative Higher capacity, 140-180mAh/g, has been partially applied. However, with the upgrading of the growing consumer electronics products, the requirements for battery energy density continue to increase. The secondary lithium battery with higher capacity, low price and good cycle performance is still the current development focus. The development of new cathode materials is one of the key technologies.

The capacity of the positive electrode material of the secondary lithium battery is related to the variable valence range of the active metal elements in the positive electrode material. In the layered compound mentioned above, in the process of lithium ion intercalation and deintercalation, the three elements of Ni, Co, and Mn mainly undergo electron transfer, that is, redox reaction. Since the valence of these three elements can vary from one valence to two valence , so its capacity is low.

It is known that the elements with higher variable valence are Cr, V, Nb, Mo and W, and there are compounds such as LiCrO ₂ , LiVO ₂ , LiNbO ₂ , LiMoO ₂ with layered structure, but these compounds have low electrochemical activity, Lithium ions cannot escape. A recent study found (Document 1: Y.Grincourt, C.Storey, and IJDavidson, J.Power Sources, 97-98, 711 (2001)), with the expression Li[Cr _x Li _{(1/3-2x /3)} The layered compound of Mn _(2/3-2x/3 )]O ₂ has a higher delithiation capacity and a higher reversible capacity, 180-210mAh/g, which shows certain promise as a positive electrode material Advantages, but the recycling of the material is poor, which is related to the fact that all metal elements in the material are variable valence elements (such as Cr, Mn). Moreover, the rate performance of the material is poor, and it cannot be discharged with a large current, which is related to the low electronic conductivity and ionic conductivity of the material.

All the above-mentioned cathode materials with layered structure are synthesized in air or oxygen. Due to the presence of elements such as Co, Ni, and Mn, when trying to coat the carbon layer on the particle surface, Co, Ni, and Mn are reduced to form low-valence compounds and directly reduce the metal, and the original layered structure is not Keep it any longer, and it can no longer be used as the positive electrode material for lithium-ion batteries. Therefore, so far, there has been no report of a layered compound whose surface is coated with a carbon material. Recent studies have shown (document 1: J.-M.TarasconM.Armand, Nature, 414, 359 (2001)) that LiFePO ₄ with an olivine structure can be coated with carbon under an inert atmosphere and a reducing atmosphere. The surface conductance of the coated particles is greatly improved, thus obtaining a material with excellent rate performance. LiFePO ₄ is an insulator with very low electronic conductivity. It can be seen that carbon coating has a significant effect on improving the surface conductance and rate performance of the material.

Contents of the invention

The object of the present invention is to overcome the above-mentioned defects and provide a positive electrode material that can make secondary lithium batteries have higher capacity, low price and good cycle performance.

The purpose of the present invention is achieved through the following technical solutions:

The invention provides a layered structure lithium-containing composite metal oxide coated with carbon on the surface, which is a composite material with a core-shell structure. The core material is lithium-containing composite metal oxide particles with a layered structure. A "shell" formed by a surrounding carbon layer.

The structural feature of the layered lithium-containing composite metal oxide as the core material is: in the direction perpendicular to the c-axis in the crystal structure, oxygen atomic layers, lithium atomic layers, and oxygen atomic layers are alternately arranged in sequence. , a metal layer and an oxygen atom layer; wherein, the metal layer is one or more selected from the active element Cr, V, Nb, Mo, W and the inactive element M, and the total valence of each element of the metal layer is 3 , to meet the requirements of electrical neutrality.

The inactive element M is an element that cannot change valence during charge and discharge, including Li and Na with a valence of one, Mg, Ca, Sr and Zn with a valence of two, Al and Ga with a valence of three, Sc, Y, La are four-valent Ti, Zr, Si, Ge.

Due to the need for charge balance, when the inactive element M is divalent, the above-mentioned tetravalent elements must exist to maintain charge balance; when M is tetravalent, the above-mentioned divalent elements can be selected to coexist, or a Valence elements to maintain charge balance. Whether the metal layer contains tetravalent, trivalent, divalent or monovalent metals, the total valence should be 3, which meets the requirement of electrical neutrality. The material allows the above-mentioned various elements to coexist in the metal layer of the layered structure.

The lithium-containing composite metal oxide of the above-mentioned layered structure conforms to the general formula of one of the following chemical formulas (1) to (4):

(1)Li[M ⁰ _x M ¹ _(1/2-x/2) M ² _(1/2-x/2) ]O _2-y X _z

Wherein, M ⁰ is one or more selected from Cr, V, Nb, Mo, W;

^M1 is one or more selected from Mg, Ca, Sr, Zn;

^M2 is one or more selected from Ti, Zr, Si, Ge;

X is one or more selected from F, S, N;

0.2≤x≤0.9, 0≤y≤0.1, 0≤z≤0.2;

(2)Li[M ⁰ _x M ¹ _(1/3-1x/3) M ² _(2/3-2x/3) ]O _2-y X _z

Wherein, M ⁰ is one or more selected from Cr, V, Nb, Mo, W;

M ¹ is Li or/and Na;

^M2 is one or more selected from Ti, Zr, Si, Ge;

X is one or more selected from F, S, N;

0.2≤x≤0.9, 0≤y≤0.1, 0≤z≤0.2;

(3) LiM ⁰ _x M _1-x O _2-y X _z

Wherein, M ⁰ is one or more selected from Cr, V, Nb, Mo, W;

M is one or more selected from Al, Ga, Sc, Y, La, In;

X is one or more selected from F, S, N;

0.2≤x≤0.9, 0≤y≤0.1, 0≤z≤0.2;

(4)Li[M ⁰ _x M ¹ _{(1/2-x/2-w/2)} M ² _w M ³ _{(1/2-x/2-w/2)} ]O _2-y X _z

Wherein M ⁰ is one or more selected from Cr, V, Nb, Mo, W;

^M1 is one or more selected from Mg, Ca, Sr, Zn;

^M2 is one or more selected from Al, Ga, Sc, Y, La, In;

^M3 is one or more selected from Ti, Zr, Si, Ge;

X is one or more selected from F, S, N;

0.2≤x≤0.9, 0<w<0.8, 0≤y≤0.1, 0≤z≤0.2.

The "shell" formed by the coated carbon layer is composed of disordered carbon and has a thickness of 2nm-5μm; the weight percentage of the carbon layer material in the entire composite material is 0.1-10wt%.

The "shell" formed by the coated carbon layer is a composite carbon layer composed of conductive carbon particles and hard carbon with a continuous disordered structure and a thickness of 10 nm to 10 μm; The weight percentage is 0.1-20wt%. Wherein, the conductive carbon particles are carbon black, acetylene black, and spherical graphite, with a diameter of 2 nm to 2 μm.

The "shell" formed by the coated carbon layer is a carbon layer composed of carbon nanotubes or carbon nanofibers with a thickness (that is, the length of carbon nanotubes or carbon nanofibers) of 50 nm to 10 μm; the carbon layer material The weight percent of the whole composite material is 0.1-10wt%. Wherein, the diameter of the carbon nanotubes or nanofibers is 2-500 nm, and the diameter of the carbon nanotubes is 1-20 nm; the carbon nanotubes or nanofibers can be straight or curved.

The layered structure lithium-containing composite metal oxide coated with carbon on the surface provided by the present invention is firstly synthesized under an inert atmosphere, its core part - the layered structure lithium-containing composite metal oxide, and then on the particle surface by pyrolysis or The chemical vapor deposition method coats a layer of carbon to form a carbon-coated composite.

When preparing the lithium-containing composite metal oxide with a layered structure, a sol-gel method or a solid-phase method can be used. The preparation process by the sol-gel method is briefly described as follows: dissolve the precursor containing Li, M ⁰ and M ¹ , M ² , M ³ , add a precipitant to form a sol-gel, heat and evaporate the solvent to obtain the precursor, and dissolve the precursor Body grinding, first sintering at 250-600°C (air, nitrogen or argon) for 2-48 hours, after grinding again, then sintering at 500-1000°C in an inert gas (nitrogen or argon) for 2-48 hours. The solid-phase method is to first mix Li, M ⁰ and the precursors of M ¹ , M ² , and M ³ evenly, then sinter in the air at 250-600 ° C, grind again, and then inert gas (nitrogen or Argon) for sintering for 2 to 48 hours.

When the lithium-containing composite metal oxide with a layered structure is coated with a carbon layer, the following various methods can be used for preparation according to the composition and structure of the surface-coated carbon layer.

(1) The direct chemical vapor deposition method is used for single carbon layer coating. Place the core material layered structure lithium-containing composite metal oxide in a tube furnace with inert gas (nitrogen, argon) and carbon source gas (ethylene, acetylene, methane or toluene, etc.), and heat at 500-1000 ° C After 2-48 hours, a layer of carbon is deposited on the surface of the core material particles.

(2) The pyrolysis method is used for single carbon layer coating. After stirring and mixing the core material with an aqueous solution or an organic solvent containing a carbon source (such as sucrose, starch, yellow dextrin, pitch, epoxy resin, polyvinyl alcohol, polyvinylidene fluoride), evaporate the water or the organic solvent, and In a tube furnace with inert gas (nitrogen, argon), heating at 500-1000° C. for 2-48 hours, a layer of carbon is deposited on the surface of the core material particles.

(3) The two-step chemical vapor deposition method is used for composite carbon layer coating. The core material layered structure lithium-containing composite metal oxide and conductive ultrafine carbon particles (such as carbon black, ultrafine graphite, acetylene black, carbon fiber, carbon nanotubes), carbon precursors (such as sucrose, starch, phenolic resin , asphalt, polyethylene oxide, polyvinylidene fluoride, etc.) are pre-mixed by mechanical stirring, heated at 300-1000°C for 2-48 hours in a tube furnace with inert gas, then cooled to room temperature, and taken out After mechanical grinding, sieving, and grading, put it in the tube furnace again, pass inert gas and carbon source gas, and heat for 2 to 48 hours, then on the surface of the core material particles, composite carbon wrapped with ultrafine conductive particles will be formed. layer, this method is called two-step chemical vapor deposition.

(4) Chemical vapor deposition is used for carbon nanotube coating. Catalyst particles such as Fe and Ni are dispersed on the surface of the core material layered structure lithium-containing composite metal oxide particles by a general impregnation method, and the core material particles loaded with the catalyst on the surface are placed in a tube furnace, and an inert gas (nitrogen gas) is introduced. , argon) and carbon source gas (ethylene, acetylene, methane or toluene, etc.), heating at 500-1000 ° C for 0.5-48 hours, a layer of carbon nanotubes will be deposited on the surface of the core material particles to form surface-grown carbon nanotubes A cage-like structure that wraps the lithium-containing composite metal oxide particles with an inner layered structure.

Through the above four methods, a carbon-coated layered structure lithium-containing composite metal oxide composite material with carbon coating layers of different structures on the surface can be prepared.

During the cladding process, within a certain temperature range, the core part of the composite material of the present invention can maintain a stable structure without phase change. Through carbon coating, the surface electronic conductance and electrical contact of the composite material are greatly improved, and at the same time, the redox side reaction between high-valent elements and electrolyte is prevented.

The layered structure lithium-containing composite metal oxide coated with carbon on the surface provided by the present invention is a carbon-coated layered structure lithium-containing composite metal oxide composite material based on a hexagonal layered crystal structure, and its core material adopts a special composition with layers Lithium-containing composite metal oxide with a similar structure, and the active element is a highly variable valence element. In addition, due to the greatly improved surface electronic conductance and electrical contact, the charge-discharge specific capacity and rate performance are further improved, the charge-discharge efficiency and cycle performance are also significantly improved, and the material is cheap and the preparation process is simple.

The layered structure lithium-containing composite metal oxide coated with carbon on the surface provided by the invention can be used in secondary lithium batteries as positive electrode active materials.

The basic structure of the secondary lithium battery using the composite material of the present invention as the positive electrode material is similar to the structure of the current secondary lithium battery, including a positive electrode with the material of the present invention as the positive electrode active material, a general negative pole, a general organic or inorganic Electrolyte solution or polymer electrolyte or solid electrolyte is composed of electrolyte, general separator, current collector, battery case and lead. One end of the positive pole and the negative pole are respectively welded with lead wires and connected to the two ends of the mutually insulated battery case or the electrode post. With the material of the present invention as the secondary lithium battery of positive electrode active material, can be made into button type (single layer), cylindrical (multilayer winding), square (multilayer folding) and other forms and specifications by the above basic structure, And it's not limited to that. The thus obtained secondary lithium battery using the composite material of the present invention as the positive electrode material has high energy density, good cycle performance, safety and reliability, especially good rate performance, and can be applied to various occasions.

Detailed ways

Example 1

Dissolve 0.02mol Cr(NO ₃ ) ₃ 9H ₂ O, 0.1267mol CH ₃ COOLi 2H ₂ O and 0.0533mol Si(OC ₂ H ₅ ) ₄ in an appropriate amount of CH ₃ CH ₂ OH, and slowly add NH ₃ . H ₂ O, adjust the pH value of the solution to 9.5-10.5, let it stand still to form a gel, place it in an oven at 100° C. for 10 hours to evaporate the solvent to dryness, and obtain the precursor. After the precursor was mechanically ball milled for 4 hours, it was heated in a tube furnace at 400°C for 10 hours under Ar gas, then mechanically ball milled for 4 hours after cooling down, and then kept in a tube furnace at 900°C for 10 hours to obtain Li[Cr _0.2 Li _0.267 Si _0.533 ]O ₂ . Li[Cr _0.2 Li _0.267 Si _0.533 ]O ₂ was placed in the tube furnace again, and toluene gas was introduced at 600°C for 30 minutes and then lowered to room temperature to obtain a layered lithium-containing composite metal coated with a disordered carbon layer on the surface Oxide composite material 1, the material has a carbon content of about 0.1% after chemical analysis. The material is studied by transmission electron microscopy, and the thickness of the carbon layer is 2nm.

The obtained composite material 1 is mixed with acetylene black and 10% polyvinylidene fluoride (PVDF) nitrogen methyl pyrrolidone solution at normal temperature and pressure to form a slurry (active material: acetylene black: PVDF=90:5:5), Evenly coated on the aluminum foil substrate, and then vacuum dried at 100°C for 5 hours, the obtained film was pressed under a pressure of 10MPa, the thickness of the obtained film was about 100μm, and cut into 1×1cm electrode sheet as the positive electrode of the simulated battery .

The negative electrode of the simulated battery uses a lithium sheet, and the electrolyte is 1mol LiPF ₆ dissolved in 1L of a mixed solvent of EC and DMC (volume ratio 1:1). The positive electrode, negative electrode, electrolyte, and separator were assembled into a simulated battery in an argon-protected glove box.

The electrochemical test steps of the simulated battery: first charge to 4.3V at 30mA/g, and then discharge to 2.0V at the same current density, the released capacity is calculated as 120mAh/g based on the mass of the composite material, and the initial charge and discharge efficiency of the material is 80%, after 50 cycles, the reversible capacity remained at 115mAh/g. When the discharge current increases to 100mA/g, the discharge capacity of the material is 80mAh/g. This current density is equivalent to the charge and discharge rate of 1C. When the current density is further increased to 1000mA/g, the discharge capacity of the material is 60mAh/g. This result indicates that composite material 1 has better high-rate discharge characteristics.

Example 2

Mix 0.01mol Cr ₂ O ₃ , 0.06335mol Li ₂ CO ₃ and 0.0533mol SiO ₂ by mechanical ball milling for 4 hours to obtain the precursor, and then keep it under Ar gas at 900°C for 10 hours to obtain Li[Cr _0.2 Li _0.267 Si _0.533 ]O ₂ . As in Example 1, the carbon layer is coated on the surface of Li[Cr _0.2 Li _0.267 Si _0.533 ]O ₂ , but the difference is that the carbon source gas is acetylene, the reaction temperature is 800°C, and the holding time is 8 hours to obtain a core-shell Structure of carbon-coated Li[Cr _0.2 Li _0.267 Si _0.533 ]O ₂ composites 2 . Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 3

Similar to Example 1, the stoichiometric ratio of the precursors was changed, and Li[Cr _0.2 Li _0.4 Si _0.2 ]O ₂ was obtained by a sol-gel method. Same as in Example 1, the carbon layer is coated on the surface of Li[Cr _0.2 Li _0.267 Si _0.533 ]O ₂ , the difference is that the carbon source gas is ethylene, the reaction temperature is 1000°C, and the holding time is 24 hours to obtain a core-shell Carbon-coated Li[Cr _0.4 Li _0.2 Si _0.4 ]O ₂ composite material 3 with the same structure as in Example 1 was used to prepare electrodes and test cells. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 4

Similar to Example 1, the stoichiometric ratio of the precursors was changed, and a sol-gel method was used to obtain Li[Cr _0.9 Li _0.033 Si _0.067 ]O ₂ . As in Example 1, a carbon layer is coated on the surface of Li[Cr _0.2 Li _0.267 Si _0.533 ]O ₂ , the difference is that the carbon source gas is methane, the reaction temperature is 1000°C, the holding time is 48 hours, and the carbon coating is obtained by cooling down. Li[Cr _0.9 Li _0.033 Si _0.067 ]O ₂ composite material 4 was coated, and electrodes and test cells were prepared by the same method as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 5

Similar to Example 2, it is obtained by a solid-state reaction method, but the difference is that 0.01 mol of V ₂ O ₃ and GeO ₂ are used as precursors. Disperse 50 grams of Li[V _0.2 Li _0.267 Ge _0.533 ]O ₂ powder into a container containing 8 grams of water-soluble starch, 80 ml of distilled water, and 20 ml of ethanol, heat the beaker while stirring, and evaporate the water to dryness within 2 hours . The resulting product was kept in a tube furnace under Ar gas at 600°C for 5 hours, and then the temperature was lowered to obtain a carbon-coated Li[V _0.2 Li _0.267 Ge _0.533 ]O ₂ composite material 5. The same method as in Example 1 was used to prepare electrodes and test Battery. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 6

Similar to Example 5, Li[Cr _0.4 Na _0.2 Ge _0.4 ]O ₂ was obtained by solid state reaction method, the difference is that the precursor was changed to 0.02mol Cr ₂ O ₃ , 0.05mol Li ₂ CO ₃ , 0.01mol Na ₂ CO ₃ and 0.04mol GeO ₂ are mixed, and the rest of the steps are the same. Disperse 50 grams of Li[Cr _0.4 Na _0.2 Ge _0.4 ]O ₂ powder into a container containing 12 grams of yellow dextrin, 80 ml of distilled water, and 20 ml of ethanol, and heat the beaker while stirring, so that the water evaporates within 2 hours. Dry. The resulting product was kept at 800°C in a tube furnace under Ar gas for 8 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.4 Na _0.2 Ge _0.4 ]O ₂ composite material 6. The same method as in Example 1 was used to prepare electrodes and test Battery. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 7

Similar to Example 5, Li[V _0.9 Na _0.033 Ge _0.067 ]O ₂ was obtained by using a solid state reaction method. Disperse 50 grams of Li[V _0.9 Na _0.033 Ge _0.067 ]O ₂ powder into a container containing 16 grams of sucrose, 80 ml of distilled water, and 20 ml of ethanol, heat the beaker while stirring, and evaporate the water to dryness within 2 hours. The resulting product was kept at 900°C in a tube furnace under Ar gas for 8 hours, and then the temperature was lowered to obtain a carbon-coated Li[V _0.9 Na _0.033 Ge _0.067 ]O ₂ composite material 7. The same method as in Example 1 was used to prepare electrodes and test Battery. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 8

Similar to Example 2, Li[Cr _0.2 Na _0.267 Zr _0.533 ]O ₂ was obtained by a solid-state reaction method, except that ZrO ₂ was used as a precursor. Disperse 50 grams of Li[Cr _0.2 Na _0.267 Zr _0.533 ]O ₂ powder into a container containing 16 grams of yellow dextrin, 80 ml of distilled water, and 20 ml of ethanol, and heat the beaker while stirring, so that the water evaporates within 2 hours. Dry. The resulting product was kept at 600°C in a tube furnace under Ar gas for 8 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.2 Na _0.267 Zr _0.533 ]O ₂ composite material 7. The same method as in Example 1 was used to prepare electrodes and test Battery. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 9

Similar to Example 8, Li[Cr _0.4 Na _0.2 Zr _0.4 ]O ₂ was obtained by a solid state reaction method. Disperse 50 grams of Li[Cr _0.4 Na _0.2 Zr _0.4 ]O ₂ powder into a container containing 12 grams of yellow dextrin, 80 ml of distilled water, and 20 ml of ethanol, and heat the beaker while stirring, so that the water evaporates within 2 hours. Dry. The resulting product was kept in a tube furnace under Ar gas at 500°C for 8 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.4 Na _0.2 Zr _0.4 ]O ₂ composite material 7. The same method as in Example 1 was used to prepare electrodes and test Battery. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 10

Similar to Example 8, Li[Cr _0.9 Na _0.033 Zr _0.067 ]O ₂ was obtained by using a solid state reaction method. Disperse 50 grams of Li[Cr _0.9 Na _0.033 Zr _0.067 ]O ₂ powder into a container containing 12 grams of yellow dextrin, 80 ml of distilled water, and 20 ml of ethanol, and heat the beaker while stirring, so that the water evaporates within 2 hours. Dry. The resulting product was kept at 600°C in a tube furnace under Ar gas for 8 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.9 Na _0.033 Zr _0.067 ]O ₂ composite material 10. The same method as in Example 1 was used to prepare electrodes and test Battery. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 11

Similar to Example 1, with 0.04mol Cr(NO ₃ ) ₃ 9H ₂ O, 0.12mol CH ₃ COOLi 2H ₂ O and 0.04mol Ti(OC ₄ H ₉ ) ₄ as reactants, according to the same conditions as in Example 1 Li[Cr _0.4 Li _0.2 Ti _0.4 ]O ₂ was prepared. Disperse 50 grams of Li[Cr _0.4 Li _0.2 Ti _0.4 ]O ₂ powder into a container containing 16 grams of yellow dextrin, 80 ml of distilled water, and 20 ml of ethanol, and heat the beaker while stirring, so that the water evaporates within 2 hours. Dry. The resulting product was kept at 1000° C. in an ethylene: argon (1:1) down-tube furnace for 48 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.4 Li _0.2 Ti _0.4 ]O ₂ composite material 11, using the same method as in Example 1. Electrodes and test cells were prepared in the same way. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 12

Analogously to Example 11, Li[Cr _0.3 Li _0.233 Ti _0.467 ]O ₂ was obtained. 50 grams of Li[Cr _0.3 Li _0.233 Ti _0.467 ]O ₂ powders are dispersed into a container containing 8 grams of asphalt and 80 ml of carbon tetrachloride, and the beaker is heated while stirring, so that the carbon tetrachloride evaporates within 1 hour. Dry. The resulting product was kept at 600°C in a tube furnace under Ar gas for 8 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.3 Li _0.233 Ti _0.467 ]O ₂ composite material 12. The same method as in Example 1 was used to prepare electrodes and test Battery. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 13

Similar to Example 2, with 0.02mol Nb ₂ O ₃ , 0.12mol LiOH·2H ₂ O, 0.02mol ZrO ₂ and 0.02mol TiO ₂ as reactants, Li[Nb _0.4 Li _0.2 Ti was prepared according to the same conditions as Example 2 _0.2 Zr _0.2 ]O ₂ . Disperse 50 grams of Li[Nb _0.4 Li _0.2 Ti _0.2 Zr _0.2 ]O ₂ powder into a container containing 8 grams of epoxy resin and 100 ml of acetone, heat the beaker while stirring, and evaporate the acetone to dryness within 1 hour. The obtained product was kept in a tube furnace under Ar gas at 600°C for 8 hours, and then the temperature was lowered to obtain a carbon-coated Li[Nb _0.4 Li _0.2 Ti _0.2 Zr _0.2 ]O ₂ composite material 13, and the electrode was prepared by the same method as in Example 1 and test batteries. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 14

Similar to Example 1, with 0.04mol Cr(NO ₃ ) ₃ 9H ₂ O, 0.12mol CH ₃ COOLi 2H ₂ O, 0.03molTi(OC ₄ H ₉ ) ₄ and 0.01mol Si(OC ₂ H ₅ ) ₄ as The reactants were prepared under the same conditions as in Example 1 to obtain Li[Cr _0.4 Li _0.2 Ti _0.3 Si _0.1 ]O ₂ . Disperse 50 grams of Li[Cr _0.4 Li _0.2 Ti _0.3 Si _0.1 ]O ₂ powder into 8 grams of polyvinyl alcohol and 100 ml of distilled water, heat the beaker while stirring, and evaporate the water to dryness within 2 hours. The resulting product was kept in a tube furnace under Ar gas at 600°C for 48 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.4 Li _0.2 Ti _0.3 Si _0.1 ]O ₂ composite material 14, and the electrode was prepared by the same method as in Example 1 and test batteries. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 15

Similar to _{Example 2 , Li [ Cr 0.4} Li _0.2 Ti _0.2 Zr _0.1 Ge _0.1 ]O ₂ . Disperse 50 grams of Li[Cr _0.4 Li _0.2 Ti _0.2 Zr _0.1 Ge _0.1 ]O ₂ powder into a container containing 8 grams of polyvinylidene fluoride and 100 ml of nitrogen methyl pyrrolidone, and heat the beaker while stirring to make the nitrogen methyl The pyrrolidone was evaporated to dryness within 2 hours. The resulting product was kept at 600°C in a tube furnace under Ar gas for 8 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.4 Li _0.2 Ti _0.2 Zr _0.1 Ge _0.1 ]O ₂ composite material 15, using the same method as in Example 1 Prepare electrodes and test cells. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 16

Similar to Example 2, with 0.02mol Cr ₂ O ₃ , 0.12mol LiOH·2H ₂ O, 0.01mol TiO ₂ , 0.01mol ZrO ₂ , 0.01mol SiO ₂ and 0.01mol GeO ₂ as reactants, according to the same method as in Example 2 Li[Cr _0.4 Li _0.2 Ti _0.1 Zr _0.1 Ge _0.1 Si _0.1 ]O ₂ was prepared under the conditions. Disperse 50 grams of Li[Cr _0.4 Li _0.2 Ti _0.1 Zr _0.1 Ge _0.1 Si _0.1 ]O ₂ powder into a container containing 8 grams of yellow dextrin, 80 ml of distilled water, and 20 ml of ethanol, and heat the beaker while stirring to make the water Evaporate to dryness within 2 hours. The resulting product was kept in a tube furnace under Ar gas at 500°C for 2 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.4 Li _0.2 Ti _0.1 Zr _0.1 Ge _0.1 Si _0.1 ]O ₂ composite material 16, using the same method as in Example 1. Methods for preparing electrodes and testing cells. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 17

Similar _{to Example 2 ,} Li[Cr _0.4 Li _0.2 Zr _0.4 ] O _1.9 F _0.1 . Disperse 50 grams of Li[Cr _0.4 Li _0.2 Zr _0.4 ]O _1.9 F _0.1 powder into a container containing 8 grams of yellow dextrin, 80 ml of distilled water, and 20 ml of ethanol, heat the beaker while stirring, and make the water in 2 hours Evaporate to dryness. The obtained product was kept in a tube furnace under Ar gas at 1000°C for 4 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.4 Li _0.2 Zr _0.4 ]O _1.9 F _0.1 composite material 17, and the electrode was prepared by the same method as in Example 1. and test batteries. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 18

_Similar to _{Example 2} , Li _[ Mo _0.4 Li _0.2 Zr _0.4 ] O _1.9 F _0.2 . Disperse 50 grams of Li[Mo _0.4 Li _0.2 Zr _0.4 ]O _1.9 F _0.2 powder into a container containing 8 grams of yellow dextrin, 80 ml of distilled water, and 20 ml of ethanol, and heat the beaker while stirring, so that the water is heated for 2 hours Evaporate to dryness. The obtained product was kept in a tube furnace under Ar gas at 500°C for 48 hours, and then the temperature was lowered to obtain a carbon-coated Li[Mo _0.4 Li _0.2 Zr _0.4 ]O _1.9 F _0.2 composite material 18, and the electrode was prepared by the same method as in Example 1. and test batteries. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 19

Similar to Example 2 _, Li[Cr _{0.4 Li 0.2 Li} [Cr _0.4 Li _0.2 Zr _0.4 ]O _1.9 S _0.1 . Disperse 50 grams of Li[Cr _0.4 Li _0.2 Zr _0.4 ]O _1.9 S _0.1 powder into a container containing 8 grams of yellow dextrin, 80 ml of distilled water, and 20 ml of ethanol, and heat the beaker while stirring, so that the water is heated for 2 hours Evaporate to dryness. The obtained product was kept in a tube furnace under Ar gas at 600°C for 24 hours, and then the temperature was lowered to obtain a carbon-coated Li[Cr _0.4 Li _0.2 Zr _0.4 ]O _1.9 S _0.1 composite material 19, and the electrode was prepared by the same method as in Example 1. and test batteries. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 20

Similar to Example 2, with 0.02mol V ₂ O ₃ , 0.09mol LiOH·2H ₂ O, 0.04mol ZrO ₂ and 0.01mol Li ₃ N as reactants, it was prepared according to the same conditions as in Example 2 (the sintering atmosphere was N ₂ ). Li[V _0.4 Li _0.2 Zr _0.4 ]O _1.9 N _0.1 is obtained. Disperse 50 grams of Li[V _0.4 Li _0.2 Zr _0.4 ]O _1.9 N _0.1 powder into a container containing 8 grams of yellow dextrin, 80 ml of distilled water, and 20 ml of ethanol, and heat the beaker while stirring, allowing the water to Evaporate to dryness. The obtained product was kept in a tube furnace under Ar gas at 600°C for 48 hours, and then the temperature was lowered to obtain a carbon-coated Li[V _0.4 Li _0.2 Zr _0.4 ]O _1.9 N _0.1 composite material 20, and the electrode was prepared by the same method as in Example 1. and test batteries. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 21

Similar to Example 1, dissolve 0.02mol Cr(NO ₃ ) ₃ ·9H ₂ O, 0.1mol CH ₃ COOLi·2H ₂ O and 0.08mol Al(NO ₃ ) ₃ in an appropriate amount of water, and slowly add NH ₃ ·H ₂ O, adjust the pH of the solution to 7.0-8.0, let it stand still to form a gel, place it in an oven at 100° C. for 10 hours to evaporate the solvent to dryness, and obtain a precursor. The precursor was mechanically ball milled for 4 hours, heated at 400°C for 10 hours under Ar gas, then mechanically ball milled for 4 hours after cooling down, and kept at 900°C for 10 hours to obtain LiCr _0.2 Al _0.8 O ₂ . Mix 50 grams of LiCr _0.2 Al _0.8 O ₂ powder with 2 grams of conductive carbon black (particle size 2nm) and 10 grams of sucrose, and use mechanical ball milling method. After ball milling for 4 hours, under Ar gas at 1000 ℃, tube Heated in a tube furnace for 2 hours, then mechanical ball milled for 4 hours after cooling down, passed through a 600 mesh sieve, put the sieved powder in the tube furnace again, raised the temperature to 1000 ° C under Ar gas, and then switched the carbon source gas ( Acetylene: argon = 1:1), after 2 hours of heat preservation, the temperature was lowered to obtain a LiCr _0.2 Al _0.8 O ₂ composite material 21 with a surface coated with a composite carbon layer. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 22

Similar to Example 1, LiCr _0.5 Al _0.5 O ₂ was obtained by a sol-gel method. Mix 50 grams of LiCr _0.5 Al _0.5 O ₂ powder with 5 grams of acetylene black (average particle size of 5 nm) and 20 grams of sucrose, and use mechanical ball milling method. After ball milling for 4 hours, under Ar gas at 800 ° C, Heated in a tube furnace for 10 hours, then mechanical ball milled for 4 hours after cooling down, passed through a 600-mesh sieve, put the sieved powder in the tube furnace again, raised the temperature to 800 ° C under Ar gas, and then switched the carbon source gas ( Acetylene: argon = 1:1), after 48 hours of heat preservation, the temperature was lowered to obtain a LiCr _0.5 Al _0.5 O ₂ composite material 22 coated with a composite carbon layer on the surface. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 23

Similar to Example 1, LiCr _0.9 Al _0.1 O ₂ was obtained by a sol-gel method. Mix 50 grams of LiCr _0.9 Al _0.1 O ₂ powder with 1 gram of conductive carbon black (average particle size of 2nm) and 5 grams of yellow dextrin, and use mechanical ball milling. Next, heat in a tube furnace for 48 hours, then mechanically ball mill for 4 hours after cooling down, pass through a 600-mesh sieve, put the sieved powder in the tube furnace again, heat up to 700°C under Ar gas, and then switch to Ethylene gas, after 24 hours of heat preservation, the temperature was lowered to obtain a LiCr _0.9 Al _0.1 O ₂ composite material 23 coated with a composite carbon layer on the surface. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 24

Similar to Example 1, with 0.05mol Cr(NO ₃ ) ₃ 9H ₂ O, 0.1mol CH ₃ COOLi 2H ₂ O and 0.05mol Sc(NO ₃ ) ₃ as reactants, it was prepared under the same conditions as in Example 1 LiCr _0.5 Sc _0.5 O ₂ . Mix 50 grams of LiCr _0.5 Sc _0.5 O ₂ powder with 1 gram of ultrafine graphite (average particle size of 2 μm) and 5 grams of starch, and use mechanical ball milling. After 4 hours of ball milling, under Ar gas at 600 ° C, Heating in a tube furnace for 10 hours, then mechanical ball milling for 4 hours after cooling down, passing through a 600-mesh sieve, putting the sieved powder in the tube furnace again, raising the temperature to 700°C under Ar gas, and then switching the carbon source gas (ethane: argon = 1:1), after 10 hours of heat preservation, the temperature was lowered to obtain a LiCr _0.5 Sc _0.5 O ₂ composite material 24 coated with a composite carbon layer on the surface. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 25

Similar to Example 1, with 0.05mol Cr(NO ₃ ) ₃ 9H ₂ O, 0.1mol CH ₃ COOLi 2H ₂ O and 0.05mol Y(NO ₃ ) ₃ as reactants, it was prepared under the same conditions as in Example 1 LiCr _0.5 Y _0.5 O ₂ . Weigh 0.01mol of Ni(NO ₃ ) ₂ ·6H ₂ O into a beaker, add 100ml of ethylene glycol, and stir to dissolve. Add 2g of LiCr _0.5 Y _0.5 O ₂ powder into 0.1MNi(NO ₃ ) ₂ 6H ₂ O 100ml ethylene glycol solution, stir at 60°C for 10 hours, separate the solid and liquid through a Buchner funnel or other filtering equipment, and then °C for 10 hours under vacuum. Put the LiCr _0.5 Y _0.5 O ₂ powder loaded with Ni catalyst in an alumina boat, then put it into a tube furnace, fill it with argon, the flow rate is 80 sccm, and after the temperature is programmed to 700 ° C, the gas is converted into acetylene Mixed gas with argon, the ratio is 3:2 (v/v), the total flow rate is 100 sccm, after chemical vapor deposition at constant temperature for 0.5 hours, the gas is converted into argon, and naturally cooled to room temperature, the surface of the obtained product grows carbon Nanotube LiCr _0.5 Y _0.5 O composite material 25, wherein the average diameter of carbon nanotubes is 2nm, the length is 50nm, and the tube diameter is 1nm. Other parameters and electrochemical performance test results are listed in Table 1.

Example 26

Similar to Example 1, with 0.09mol Cr(NO ₃ ) ₃ 9H ₂ O, 0.1mol CH ₃ COOLi 2H ₂ O and 0.01mol La(NO ₃ ) ₃ as reactants, it was prepared under the same conditions as in Example 1 LiCr _0.9 La _0.1 O ₂ . Similar to Example 25, a LiCr _0.9 La _0.1 O ₂ composite material 26 with carbon nanotubes grown on the surface was prepared, except that the temperature was kept constant for 48 hours. The carbon nanotubes have an average diameter of 100 nm, a length of 10 μm, and a tube diameter of 2 nm. Other parameters and electrochemical performance test results are listed in Table 1.

Example 27

Similar to Example 2, LiCr _0.5 Ga 0.5 O ₂ was prepared by using 0.025 mol Cr ₂ O ₃ , 0.1 mol LiOH·2H ₂ O, and _0.025 mol Ga ₂ O ₃ as reactants. Similar to Example 25, a LiCr _0.5 Ga _0.5 O ₂ composite material 27 with carbon nanotubes grown on the surface was prepared, the difference is that 0.2M Ni(NO ₃ ) ₂ ·6H ₂ O in 100ml ethanol solution was used as the catalyst precursor , all the other conditions are the same as in Example 26. The carbon nanotubes have an average diameter of 500 nm, a length of 10 μm, and a diameter of 20 nm. Other parameters and electrochemical performance test results are listed in Table 1.

Example 28

Similar to Example 1, with 0.05mol Cr(NO ₃ ) ₃ 9H ₂ O, 0.1mol CH ₃ COOLi 2H ₂ O and 0.05molIn(NO ₃ ) ₃ 3H ₂ O as reactants, the same as in Example 1 LiCr _0.5 In _0.5 O ₂ was prepared under the conditions. Weigh 0.0001mol (NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O into a beaker, add 100ml of methanol, stir to dissolve; then add 10g of LiCr _0.5 Ga _0.5 O ₂ powder into this solution, stir at 25°C for 10 hours, separated the solid and liquid through a Buchner funnel or other filtering equipment, and then dried in vacuum at 100°C for 10 hours; the resulting material was placed in an alumina boat, then loaded into a tube furnace, filled with argon, and the flow rate was 80sccm, after the program temperature rises to 800°C, the gas is converted to argon and flows through the toluene bottle at a flow rate of 100sccm. After chemical vapor deposition at a constant temperature for 48 hours, the gas is converted to argon, and naturally cooled to room temperature. The resulting product is carbon fiber grown on the surface LiCr _0.5 Ga _0.5 O ₂ composite material, on which the average diameter of carbon fibers is 500nm and the length is 10um. The electrochemical performance test results of LiCr _0.5 Ga _0.5 O ₂ composites with carbon fibers grown on the surface are listed in Table 1.

Example 29

With 0.025mol Cr ₂ O ₃ , 0.09mol LiOH·2H ₂ O, 0.025mol Al ₂ O ₃ and 0.01mol LiF as reactants, LiCr _0.5 Al _0.5 O _1.9 F _0.1 was prepared according to the same conditions as in Example 2. Weigh 0.001mol Ni(NO ₃ ) ₂ ·6H ₂ O and 0.000015mol Cu(NO ₃ ) ₂ .6H ₂ O into a beaker, add 100ml of isopropanol, and stir to dissolve. Then 10g of LiCr _0.5 Al _0.5 O _1.9 F _0.1 powder was added to this solution, stirred at 25°C for 5 hours, separated from solid and liquid by Buchner funnel or other filtering equipment, and then dried in vacuum at 100°C for 10 hours; The substance is placed in an alumina boat, then loaded into a tube furnace, filled with argon, with a flow rate of 80 sccm, and after the temperature is programmed to 800°C, the gas is converted into methane gas with a total flow rate of 100 sccm, and the chemical vapor phase is performed at a constant temperature for 24 hours After deposition, the gas was changed to argon, and naturally cooled to room temperature. The obtained product was LiCr _0.5 Al _0.5 O _1.9 F _0.1 composite material 29 with carbon fibers grown on the surface. The average diameter of the carbon fibers on it was 2 nm and the length was 50 nm. Electrodes and test cells were prepared in the same manner as in Example 1. Its electrochemical performance test results are listed in Table 1.

Example 30

With 0.025mol Cr ₂ O ₃ , 0.08mol LiOH·2H ₂ O, 0.025mol Al ₂ O ₃ and 0.01mol Li ₂ S as reactants, LiCr _0.5 Al _0.5 O _1.9 S _0.1 was prepared according to the same conditions as in Example 2. Weigh 0.0001mol Fe(NO ₃ ) ₂ 6H ₂ O into a beaker, add 100ml of isopropanol, stir to dissolve; then add 10g of LiCr _0.5 Al _0.5 O _1.9 S _0.1 powder (average particle size 200nm) into this In a solution, stir at 25°C for 1 hour, separate the solid and liquid through a Buchner funnel or other filtering equipment, and then vacuum dry at 100°C for 10 hours; place the resulting material in an alumina boat, and then load it into a tube Furnace, filled with argon gas, the flow rate is 80 sccm, after the temperature is programmed to 600 ° C, the gas is converted into acetylene gas, the total flow rate is 100 sccm, after chemical vapor deposition at constant temperature for 2 hours, the gas is converted into argon gas, and naturally cooled to room temperature , the obtained product is the LiCr _0.5 Al _0.5 O _1.9 S _0.1 composite material with carbon nanotubes grown on the surface, wherein the average diameter of the carbon nanotubes is 50nm and the length is 2um. Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 31

With 0.025mol Cr ₂ O ₃ , 0.07mol LiOH·2H ₂ O, 0.025mol Al ₂ O ₃ and 0.01mol Li ₃ N as reactants, LiCr _0.5 Al was prepared according to the same conditions as in Example 2 (the sintering atmosphere was N2) _0.5 O _1.9 N _0.1 . As in Example 2, a carbon layer was coated on the surface of LiCr _0.5 Al _0.5 O _1.9 N _0.1 to obtain a carbon-coated LiCr _0.5 Al _0.5 O _1.9 N _0.1 composite material 31 with a core-shell structure. Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 32

Using 0.01mol Cr ₂ O ₃ , 0.1mol LiOH·2H ₂ O, 0.04mol TiO ₂ , and 0.04mol MgO as reactants, Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O ₂ was prepared according to the same conditions as in Example 2. Mix 50 grams of Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O ₂ with 2 grams of conductive carbon black (20nm particle size) and 5 grams of starch, and use mechanical ball milling. Next, heat in a tube furnace for 48 hours, then mechanically ball mill for 4 hours after cooling down, pass through a 600-mesh sieve, put the sieved powder in the tube furnace again, heat up to 700°C under Ar gas, and then switch to Ethylene gas, after 24 hours of heat preservation, the temperature was lowered to obtain a Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O ₂ composite material 32 coated with a composite carbon layer on the surface. Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 33

Using 0.02mol Cr ₂ O ₃ , 0.1mol LiOH·2H ₂ O, 0.03mol SiO ₂ , and 0.03mol SrO as reactants, Li[Cr _0.4 Sr _0.3 Si _0.3 ]O ₂ was prepared according to the same conditions as in Example 2. Mix 50 grams of Li[Cr _0.4 Sr _0.3 Si _0.3 ]O ₂ with 2 grams of acetylene black (particle size 40nm), and 5 grams of phenolic resin, and use mechanical ball milling. After 4 hours of ball milling, the Next, heat in a tube furnace for 48 hours, then mechanically ball mill for 4 hours after cooling down, pass through a 600-mesh sieve, put the sieved powder in the tube furnace again, heat up to 700°C under Ar gas, and then switch to Ethylene gas, after 24 hours of heat preservation, the temperature was lowered to obtain a Li[Cr _0.4 Sr _0.3 Si _0.3 ]O ₂ composite material 33 coated with a composite carbon layer on the surface. Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 34

With 0.015mol Cr ₂ O ₃ , 0.005mol V ₂ O ₃ , 0.005mol Mo ₂ O ₃ , 0.01mol Nb ₂ O ₃ , 0.02mol WO ₂ , 0.1mol LiOH·2H ₂ O, 0.005mol Ca(OH) ₂ , Li[Cr _0.3 V _0.1 Mo _0.1 Nb _0.2 W _0.2 Ca _0.05 Zr _0.05 ]O ₂ was prepared according to the same conditions as in Example 2 with 0.005 mol ZrO ₂ as the reactant. Mix 50 grams of Li[Cr _0.3 V _0.1 Mo _0.1 Nb _0.2 W _0.2 Ca _0.05 Zr _0.05 ]O ₂ with 2 grams of conductive carbon black (20nm particle size), 5 grams of polyethylene oxide, and use mechanical ball milling Method: After ball milling for 4 hours, under Ar gas at 600°C, heat in a tube furnace for 8 hours, then mechanically ball mill for 4 hours after cooling down, pass through a 600-mesh sieve, and put the sieved powder in the tube furnace again. The temperature was raised to 800°C under Ar gas, and then switched to acetylene gas. After 8 hours of heat preservation, the temperature was lowered to obtain a Li[Cr _0.3 V _0.1 Mo _0.1 Nb _0.2 W _0.2 Ca _0.05 Zr _0.05 ]O ₂ composite material coated with a composite carbon layer 34. Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 35

Using 0.02mol Cr ₂ O ₃ , 0.1mol LiOH·2H ₂ O, 0.03mol ZnO, and 0.03mol GeO ₂ as reactants, Li[Cr _0.4 Zn _0.3 Ge _0.3 ]O ₂ was prepared according to the same conditions as in Example 2. Mix 50 grams of Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O ₂ with 2 grams of conductive carbon black (20nm particle size) and 5 grams of starch, and use mechanical ball milling. Next, heat in a tube furnace for 48 hours, then mechanically ball mill for 4 hours after cooling down, pass through a 600-mesh sieve, put the sieved powder in the tube furnace again, heat up to 700°C under Ar gas, and then switch to Ethylene gas, after holding for 24 hours, lower the temperature to obtain a surface-coated composite carbon layer. Obtain a carbon layer coated on the surface of Li[Cr _0.4 Zn _0.3 Ge _0.3 ]O ₂ to obtain a carbon-coated Li[Cr _0.4 Zn with a core-shell structure _0.3 Ge _0.3 ]O ₂ composite material 30 . Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1

Example 36

With 0.01mol Cr ₂ O ₃ , 0.08mol LiOH·2H ₂ O, 0.04mol MgO, 0.04mol TiO ₂ and 0.02mol LiF as reactants, Li[Cr _0.2 Mg _0.4 Ti _0.4 ] was prepared according to the same conditions as in Example 2 O _1.9 F _0.2 . With 50 grams of Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O _1.9 F _0.2 and 2 grams of conductive carbon black (particle size is 40nm), 5 grams of polyvinylidene fluoride are mixed together, adopt the method for mechanical ball milling, after ball milling 4 hours, Under Ar gas at 500°C, heat in a tube furnace for 4 hours, then mechanically ball mill for 4 hours after cooling down, pass through a 600-mesh sieve, put the sieved powder in a tube furnace again, and heat up to 800 °C under Ar gas. ℃, and then switched to ethylene gas. After 24 hours of heat preservation, the temperature was lowered to obtain a Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O _1.9 F _0.2 composite material 36 coated with a composite carbon layer. Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 37

With 0.01mol Cr ₂ O ₃ , 0.08mol LiOH·2H ₂ O, 0.04mol MgO, 0.04mol TiO ₂ and 0.01mol Li ₂ S as reactants, Li[Cr _0.2 Mg _0.4 Ti _0.4 ] O _1.9 S _0.1 . As in Example 2, a carbon layer was coated on the surface of Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O _1.9 S _0.1 to obtain a carbon-coated Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O _1.9 S _0.1 composite material with a core-shell structure 37 . Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 38

With 0.01mol Cr ₂ O ₃ , 0.07mol LiOH·2H ₂ O _, 0.04mol MgO, 0.04mol TiO ₂ and 0.01mol Li ₃ N as reactants, Li [Cr _0.2 Mg _0.4 Ti _0.4 ]O _1.9 N _0.1 . Same as Example 2, in Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O _1.9 N _0.1 composite material 38. Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 39

With 0.01mol Cr ₂ O ₃ , 0.1mol LiOH·2H ₂ O, 0.035mol MgO, 0.005mol Al ₂ O ₃ and 0.035mol TiO ₂ as reactants, Li[Cr _0.2 Mg _0.35 Al was prepared according to the same conditions as in Example 2 _0.1 Ti _0.35 ]O ₂ . As in Example 2, a carbon layer was coated on the surface of Li[Cr _0.2 Mg _0.35 Al _0.1 Ti _0.35 ]O ₂ to obtain a carbon-coated Li[Cr _0.2 Mg _0.35 Al _0.1 Ti _0.35 ]O ₂ composite material with a core-shell structure 39 . Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 40

With 0.01mol Cr ₂ O ₃ , 0.1mol LiOH·2H ₂ O, 0.001mol Ca(OH) ₂ , 0.078mol In(NO ₃ ) ₃ ·3H ₂ O and 0.001mol ZrO ₂ as reactants, the same as in Example 2 Li[Cr _0.2 Ca _0.01 In _0.78 Zr _0.01 ]O ₂ was prepared under the above conditions. As in Example 2, a carbon layer was coated on the surface of Li[Cr _0.2 Ca _0.01 In _0.78 Zr _0.01 ]O ₂ to obtain a carbon-coated Li[Cr _0.2 Ca _0.01 In _0.78 Zr _0.01 ]O ₂ composite material 40 with a core-shell structure . Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 41

With 0.02mol Cr ₂ O ₃ , 0.1mol LiOH·2H ₂ O, 0.015mol SrO, 0.015mol Ga ₂ O ₃ and 0.015mol GeO ₂ as reactants, Li[Cr _0.4 Sr _0.15 Ga _0.3 Ge _0.15 ]O ₂ . As in Example 2, a carbon layer was coated on the surface of Li[Cr _0.4 Sr _0.15 Ga _0.3 Ge _0.15 ]O ₂ to obtain a carbon-coated Li[Cr _0.4 Sr _0.15 Ga _0.3 Ge _0.15 ]O ₂ composite material 41 with a core-shell structure . Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 42

With 0.045mol Cr ₂ O ₃ , 0.1mol LiOH·2H ₂ O, 0.003mol MgO, 0.002mol Y ₂ O ₃ and 0.003mol SiO ₂ as reactants, Li[Cr _0.9 Mg _0.03 Y _0.04 Si _0.03 ]O ₂ . As in Example 2, a carbon layer was coated on the surface of Li[Cr _0.9 Mg _0.03 Y _0.04 Si _0.03 ]O ₂ to obtain a carbon-coated Li[Cr _0.9 Mg _0.03 Y _0.04 Si _0.03 ]O ₂ composite material 42 with a core-shell structure . Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 43

With 0.015mol Cr ₂ O ₃ , 0.1mol LiOH·2H ₂ O, 0.01mol Ca(OH) ₂ , 0.05mol Sc(NO ₃ ) ₃ and 0.01mol ZrO ₂ as reactants, it was prepared under the same conditions as in Example 2 Li[Cr _0.3 Ca _0.1 Sc _0.5 Zr _0.1 ]O ₂ . As in Example 2, a carbon layer was coated on the surface of Li[Cr _0.3 Ca _0.1 Sc _0.5 Zr _0.1 ]O ₂ to obtain a carbon-coated Li[Cr _0.3 Ca _0.1 Sc _0.5 Zr _0.1 ]O ₂ composite material 43 with a core-shell structure . Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 44

With 0.025mol Cr ₂ O ₃ , 0.08mol LiOH·2H ₂ O, 0.01mol MgO, 0.015mol La ₂ O ₃ , 0.01mol TiO ₂ and 0.02mol LiF as reactants, Li[Cr _0.5 Mg _0.1 La _0.3 Ti _0.1 ]O _1.9 F _0.2 . As in Example 2, a carbon layer is coated on the surface of Li[Cr _0.5 Mg _0.1 La _0.3 Ti _0.1 ]O _1.9 F _0.2 to obtain a carbon-coated Li[Cr _0.5 Mg _0.1 La _0.3 Ti _0.1 ]O _1.9 F with a core-shell structure _0.2 Composites 44. Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1

Example 45

With 0.025mol Cr ₂ O ₃ , 0.08 mol LiOH·2H ₂ O, 0.01 mol MgO, 0.015 mol Al ₂ O ₃ , 0.01 mol TiO ₂ and 0.01 mol Li ₂ S as reactants, Li [Cr _0.5 Mg _0.1 Al _0.3 Ti _0.1 ]O _1.9 S _0.1 . As in Example 2, the carbon layer is coated on the surface of Li[Cr _0.5 Mg _0.1 Al _0.3 Ti _0.1 ]O _1.9 S _0.1 to obtain carbon-coated Li[Cr _0.5 Mg _0.1 Al _0.3 Ti _0.1 ]O _1.9 S with a core-shell structure _0.1 Composites 45. Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Example 46

With 0.025mol Cr ₂ O ₃ , 0.07mol LiOH·2H ₂ O, 0.01mol MgO, 0.015mol Al ₂ O ₃ , 0.01mol TiO ₂ and 0.01mol Li ₃ N as reactants, according to the same conditions as in Example 2 (sintering atmosphere Li[Cr _0.5 Mg _0.1 Al _0.3 Ti _0.1 ]O _1.9 N _0.1 was prepared for N ₂ ). As in Example 2, the carbon layer is coated on the surface of Li[Cr _0.5 Mg _0.1 Al _0.3 Ti _0.1 ]O _1.9 N _0.1 to obtain a carbon-coated Li[Cr _0.5 Mg _0.1 Al _0.3 Ti _0.1 ]O _1.9 N with a core-shell structure _0.1 Composites 46. Electrodes and test cells were prepared in the same manner as in Example 1. The coating parameters and electrochemical performance test results are listed in Table 1.

Table 1. Composition and electrochemical properties of the layered structure lithium-containing composite metal oxide coated with carbon of the present invention

serial number Lithium-containing composite metal oxide carbon-coated composites with layered structure Electrochemical properties Li[Cr _x Li _(1/3-x/3) M _(2/3-2x/3) ]O _2-y X _z carbon coating Reversible capacity initial efficiency 50 weeks capacity content thickness wt% μm mAh/g % mAh/g 1 Li[Cr _0.2 Li _0.267 Si _0.533 ]O ₂ 0.1 0.002 120 80 115 2 Li[Cr _0.2 Li _0.267 Si _0.533 ]O ₂ 5 1 140 82 135 3 Li[Cr _0.4 Li _0.2 Si _0.4 ]O ₂ 5 1 180 85 170 4 Li[Cr _0.9 Li _0.033 Si _0.067 ]O ₂ 10 5 140 70 130 5 Li[V _0.2 Li _0.267 Ge _0.533 ]O ₂ 3 0.5 128 72 105 6 Li[Cr _0.4 Na _0.2 Ge _0.4 ]O ₂ 5 2 195 86 185 7 Li[V _0.9 Na _0.033 Ge _0.067 ]O ₂ 8 3 175 84 168 8 Li[Cr _0.2 Na _0.267 Zr _0.533 ]O ₂ 8 3 142 80 128 9 Li[Cr _0.4 Na _0.2 Zr _0.4 ]O ₂ 5 2 200 85 185 10 Li[Cr _0.9 Na _0.033 Zr _0.067 ]O ₂ 5 2 140 70 110 11 Li[Cr _0.4 Li _0.2 Ti _0.4 ]O ₂ 10 5 205 85 195 12 Li[Cr _0.3 Li _0.233 Ti _0.467 ]O ₂ 5 2 165 82 150 13 Li[Nb _0.4 Li _0.2 Ti _0.2 Zr _0.2 ]O ₂ 5 2 195 82 190 14 Li[Cr _0.4 Li _0.2 Ti _0.3 Si _0.1 ]O ₂ 5 2 165 75 145 15 Li[Cr _0.4 Li _0.2 Ti _0.2 Zr _0.1 Ge _0.1 ]O ₂ 5 2 155 73 140 16 Li[Cr _0.4 Li _0.2 Ti _0.1 Zr _0.1 Ge _0.1 Si _0.1 ]O ₂ 4 1 180 81 168 17 Li[Cr _0.4 Li _0.2 Zr _0.4 ]O _1.9 F _0.1 5 2 182 87 175 18 Li[Mo _0.4 Li _0.2 Zr _0.4 ]O _1.9 F _0.2 5 2 145 70 110 19 Li[Cr _0.4 Li _0.2 Zr _0.4 ]O _1.9 S _0.1 5 2 184 74 173 20 Li[V _0.4 Li _0.2 Zr _0.4 ]O _1.9 N _0.1 5 2 136 71 110 twenty one _{LiCr0.2Al0.8O2 _ _} 10 5 160 89 155 twenty two _{LiCr0.5Al0.5O2 _ _} 20 10 210 86 188

twenty three _{LiCr0.9Al0.1O2 _ _} 5 3 172 90 165 twenty four _{LiCr0.5Sc0.5O2 _ _} 6 4 178 89 162 25 _{LiCr0.5Y0.5O2 _ _} 5 / 186 90 175 26 _{LiCr0.9La0.1O2 _ _} 5 / 182 91 168 27 _{LiCr0.5Ga0.5O2 _ _} 5 / 178 92 166 28 LiCr _0.5 In _0.5 O ₂ 10 / 136 94 128 29 LiCr _0.5 Al _0.5 O _1.9 F _0.1 0.1 / 215 93 208 30 LiCr _0.5 Al _0.5 O _1.9 S _0.1 3 / 210 91 205 31 LiCr _0.5 Al _0.5 O _1.9 N _0.1 5 / 190 91 188 32 Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O ₂ 2 0.5 164 94 148 33 Li[Cr _0.4 Sr _0.3 Si _0.3 ]O ₂ 5 2 178 92 168 34 Li[Cr _0.3 V _0.1 Mo _0.1 Nb _0.2 W _0.2 Ca _0.05 Zr _0.05 ]O ₂ 7 2 162 92 156 35 Li[Cr _0.4 Zn _0.3 Ge _0.3 ]O ₂ 6 4 174 93 164 36 Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O _1.9 F _0.2 8 5 148 90 120 37 Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O _1.9 S _0.1 5 3 138 93 126 38 Li[Cr _0.2 Mg _0.4 Ti _0.4 ]O _1.9 N _0.1 5 3 140 93 132 39 Li[Cr _0.2 Mg _0.35 Al _0.1 Ti _0.35 ]O ₂ 4 2 136 90 128 40 Li[Cr _0.2 Ca _0.01 In _0.78 Zr _0.01 ]O ₂ 4 3 100 91 94 41 Li[Cr _0.4 Sr _0.15 Ga _0.3 Ge _0.15 ]O ₂ 4 3 184 92 148 42 Li[Cr _0.9 Mg _0.03 Y _0.04 Si _0.03 ]O ₂ 4 3 210 94 188 43 Li[Cr _0.3 Ca _0.1 Sc _0.5 Zr _0.1 ]O ₂ 4 3 185 92 168 44 Li[Cr _0.5 Mg _0.1 La _0.3 Ti _0.1 ]O _1.9 F _0.2 4 3 192 90 182 45 Li[Cr _0.5 Mg _0.1 Al _0.3 Ti _0.1 ]O _1.9 S _0.1 4 3 177 86 162 46 Li[Cr _0.5 Mg _0.1 Al _0.3 Ti _0.1 ]O _1.9 N _0.1 4 3 193 85 183

Claims (10)

1, a kind of lamina-structure lithium-contained composite metal oxide of coated with carbon, it is the composite material of a nucleocapsid structure, core material is the lithium-contained composite metal oxide particle with layer structure, is " shell " that a coating carbon-coating forms on its surface.

2, the lamina-structure lithium-contained composite metal oxide of coated with carbon as claimed in claim 1, it is characterized in that: the architectural feature of the lithium-contained composite metal oxide of described layer structure as core material is: on perpendicular to the c direction of principal axis in the crystal structure, and alternately arranging successively oxygen atomic layer, lithium atom layer, oxygen atomic layer, metal level and oxygen atomic layer; Wherein, in the metal level for being selected from active element Cr, V, Nb, Mo, one or more in W and the nonactive element M, and the total chemical valence of each element of metal level is 3, satisfies electroneutral requirement;

The element of described nonactive element M for appraising at the current rate in charge and discharge process comprises that chemical valence is the Li and the Na of monovalence, and chemical valence is the Mg of divalence, and Ca, Sr and Zn, chemical valence are the Al of trivalent, Ga, and Sc, Y, La, chemical valence are the Ti of tetravalence, Zr, Si, Ge.

3, the lamina-structure lithium-contained composite metal oxide of coated with carbon as claimed in claim 1 is characterized in that: the chemical formula of the lithium-contained composite metal oxide of described layer structure is Li[M ⁰ _xM ¹ _(1/2-x/2)M ² _(1/2-x/2)] O _2-yX _z

Wherein, M ⁰For being selected from Cr, V, Nb, Mo, one or more among the W;

M ¹For being selected from Mg, Ca, Sr, one or more among the Zn;

M ²For being selected from Ti, Zr, Si, one or more among the Ge;

X is for being selected from F, S, one or more among the N;

0.2≤x≤0.9，0≤y≤0.1，0≤z≤0.2。

4, the lamina-structure lithium-contained composite metal oxide of coated with carbon as claimed in claim 1 is characterized in that: the chemical formula of the lithium-contained composite metal oxide of described layer structure is Li[M ⁰ _xM ¹ _{(1/3-1 x/3)}M ² _(2/3-2x/3)] O _2-yX _z

Wherein, M ⁰For being selected from Cr, V, Nb, Mo, one or more among the W;

M ¹For Li or/and Na;

M ²For being selected from Ti, Zr, Si, one or more among the Ge;

X is for being selected from F, S, one or more among the N;

0.2≤x≤0.9，0≤y≤0.1，0≤z≤0.2。

5, the lamina-structure lithium-contained composite metal oxide of coated with carbon as claimed in claim 1 is characterized in that: the chemical formula of the lithium-contained composite metal oxide of described layer structure is LiM ⁰ _xM _1-xO _2-yX _z

Wherein, M ⁰For being selected from Cr, V, Nb, Mo, one or more among the W;

M is for being selected from Al, Ga, Sc, Y, La, one or more among the In;

X is for being selected from F, S, one or more among the N;

0.2≤x≤0.9，0≤y≤0.1，0≤z≤0.2。

6, the lamina-structure lithium-contained composite metal oxide of coated with carbon as claimed in claim 1 is characterized in that: the chemical formula of the lithium-contained composite metal oxide of described layer structure is

Li[M ⁰ _xM ¹ _{(1/2-x/2-w/2)}M ² _wM ³ _{(1/2-x/2-w/2)}]O _2-yX _z

M wherein ⁰For being selected from Cr, V, Nb, Mo, one or more among the W;

M ¹For being selected from Mg, Ca, Sr, one or more among the Zn;

M ²For being selected from Al, Ga, Sc, Y, La, one or more among the In;

M ³For being selected from Ti, Zr, Si, one or more among the Ge;

X is for being selected from F, S, one or more among the N;

0.2≤x≤0.9，0＜w＜0.8，0≤y≤0.1，0≤z≤0.2。

7, the lamina-structure lithium-contained composite metal oxide of coated with carbon as claimed in claim 1 is characterized in that: " shell " that described coating carbon-coating forms, form by the carbon of disordered structure, thickness is the carbon-coating of 2 nm～5 μ m; The percentage by weight that this carbon-coating material accounts for whole composite material is 0.1～10 wt%.

8, the lamina-structure lithium-contained composite metal oxide of coated with carbon as claimed in claim 1, it is characterized in that: " shell " that described coating carbon-coating forms, form by the hard carbon of conductive carbon particle and continuous disordered structure, thickness is the compound carbon-coating of 10 nm～10 μ m; The percentage by weight that this compound carbon-coating accounts for whole composite material is 0.1～20wt%.Wherein, described conductive carbon particle is a carbon black, acetylene black, and spherical graphite, diameter are 2nm～2 μ m.

9, the lamina-structure lithium-contained composite metal oxide of coated with carbon as claimed in claim 1, it is characterized in that: " shell " that described coating carbon-coating forms is that one that be made up of carbon nano-tube or carbon nano-fiber, thickness (being carbon nano-tube or carbon nano-fiber length) is the carbon-coating of 50nm～10 μ m; The percentage by weight that this carbon-coating material accounts for whole composite material is 0.1～10 wt%.Wherein, the diameter of described carbon nano-tube or nanofiber is 2～500nm, and the caliber of carbon nano-tube is 1～20 nm.

10, the lamina-structure lithium-contained composite metal oxide of coated with carbon as claimed in claim 1 is as the purposes of the positive electrode active materials of serondary lithium battery.