Composite positive electrode material, preparation method thereof and lithium ion battery

Abstract

The invention is suitable for the technical field of materials, and provides a composite positive electrode material and a preparation method thereof, and a lithium ion battery. A lithium source, a manganese source, an iron source, a phosphorus source, a carbon source and a yttrium source and / or a tantalum source are sequentially subjected to dry grinding and wet grinding mixing treatment, and a powder precursor is obtained through drying and ball milling; and heating to different temperatures at a specific heating rate in an inert gas atmosphere, and carrying out heat preservation reaction to finally obtain the composite positive electrode material with excellent electrochemical performance. Wherein the doping source design of the yttrium source and / or the tantalum source and the specific molar ratio control effectively improve the conductivity of the lithium manganese iron phosphate and the lithium ion diffusion rate, and solve the problem of poor rate capability; and the high-temperature solid-phase carbon thermal reduction roasting reaction further optimizes the material structure, and improves the cycling stability and energy density of the material. The method disclosed by the invention is simple to operate, low in preparation cost and high in production capacity, provides a new way for low-cost development of the high-performance lithium ion battery positive electrode material, and has a good application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of material technology, and in particular relates to a composite positive electrode material and a preparation method thereof, and a lithium ion battery. Background Art

[0002] The energy density of lithium iron phosphate has almost reached its upper limit, and lithium iron manganese phosphate has broken the bottleneck. According to the latest catalog of recommended models for the promotion and application of new energy vehicles in the fifth batch in 2022 released by the Ministry of Industry and Information Technology, the energy density of lithium iron phosphate batteries reaches up to 161.27Wh / kg, and has not changed much in recent years. As a result, lithium iron phosphate has developed. Battery energy density = battery capacity * voltage platform / weight. The theoretical gram capacity of lithium iron phosphate batteries is 170mAh / g, which has almost reached its limit. Therefore, increasing the voltage platform is the decisive factor in improving energy density. Lithium iron manganese phosphate is a new type of phosphate obtained by doping a certain proportion of manganese on the basis of lithium iron phosphate. The high voltage characteristics of manganese give lithium iron phosphate a higher voltage platform than lithium iron phosphate, thus breaking the current upper limit of battery energy density.

[0003] Compared to lithium iron phosphate, lithium iron phosphate (LFP) boasts higher voltage, higher energy density, and better low-temperature performance. While both LFP and LFP have the same theoretical capacity (170 mAh / g), LFP's voltage platform is only 3.4V, while LFP's can reach up to 4.1V. This is within the stable electrochemical window of organic electrolyte systems, giving LFP a higher energy density ceiling.

[0004] The structural characteristics of lithium manganese iron phosphate (LMP) lead to its poor conductivity and low lithium ion diffusion rate, which in turn affect its rate performance. LMP has a hexagonal close-packed structure, with FeO6 and MnO6 located on octahedra and cross-linked by PO4 tetrahedra. There is no continuous network of FeO6 (MnO6) edge-sharing octahedra, resulting in poor conductivity. Furthermore, the PO4 tetrahedra located between the FeO6 (MnO6) octahedra block the lithium ion diffusion channels, restricting their movement to a one-dimensional channel. This results in a relatively low lithium ion diffusion rate and poor rate performance. The structural characteristics of LMP determine its poor conductivity and low lithium ion diffusion rate, which in turn affect its rate performance. The Jahn-Teller effect promotes manganese precipitation, leading to a decrease in cycle life and reduced cycle stability. The Jahn-Teller effect refers to the distortion of the molecular geometry caused by the asymmetric occupation of electrons in degenerate orbitals. These shortcomings prevent LMP from fully realizing its electrochemical properties, thus limiting its further large-scale application. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide a method for preparing a composite positive electrode material, aiming to solve the problem that the existing lithium manganese iron phosphate battery has poor electrochemical performance, which limits its large-scale application.

[0006] The embodiment of the present invention is achieved by a method for preparing a composite positive electrode material, comprising:

[0007] The lithium source, manganese source, iron source, phosphorus source, carbon source and doping source are sequentially subjected to dry grinding and wet grinding, and then dried and ball milled to obtain a powder precursor; wherein the doping source is a yttrium source and / or a tantalum source. When only the yttrium source is involved, the Y 3+ :PO4 3- The molar ratio of Ta is 0.1; when only tantalum source is involved, 5+ :PO4 3- The molar ratio of Y is 0.1; when both yttrium source and tantalum source are involved, 3+ and Ta 5+ :PO4 3- The molar ratio is controlled within the range of 0.2-0.3;

[0008] Under an inert gas atmosphere, the powder precursor is heated to 350°C at a heating rate of 2-5°C / min for heat preservation and reaction, and is heated to 650-750°C at a heating rate of 3-5°C / min for heat preservation and reaction, and is cooled and ground to obtain a composite positive electrode material.

[0009] Another object of an embodiment of the present application is a composite positive electrode material, which is prepared by the above-mentioned method for preparing the composite positive electrode material.

[0010] Another object of an embodiment of the present application is a lithium-ion battery, which includes the above-mentioned composite positive electrode material.

[0011] The preparation method of the composite positive electrode material provided in the embodiment of the present application is to dry-grind and wet-grind the doping sources of lithium source, manganese source, iron source, phosphorus source, carbon source and yttrium source and / or tantalum source in sequence, obtain a powder precursor by drying and ball milling, and heat it to different temperatures at a specific heating rate under an inert gas atmosphere for insulation reaction, and finally obtain a composite positive electrode material with excellent electrochemical properties. Among them, the doping source design of yttrium source and / or tantalum source and the specific molar ratio control effectively improve the conductivity and lithium ion diffusion rate of lithium manganese iron phosphate, and solve the problem of its poor rate performance; and the high-temperature solid-phase carbon thermal reduction roasting reaction further optimizes the material structure and improves the cycle stability and energy density of the material. The method of the present application is simple to operate, low in preparation cost, and large in production capacity. It provides a new way for the low-cost development of high-performance lithium-ion battery positive electrode materials and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is an SEM image of the composite positive electrode material provided in Example 4 of the present application;

[0013] Figure 2 This is an SEM image of the composite positive electrode material provided in Example 3 of the present application;

[0014] Figure 3 This is an SEM image of the composite cathode material provided in Example 6 of the present application;

[0015] Figure 4 This is an SEM image of the composite positive electrode material provided in Comparative Example 9 of the present application;

[0016] Figure 5 This is an SEM image of the composite cathode material provided in Example 8 of the present application;

[0017] Figure 6 This is an SEM image of the composite positive electrode material provided in Example 7 of the present application;

[0018] Figure 7 This is an SEM image of the composite positive electrode material provided in Comparative Example 10 of the present application;

[0019] Figure 8 This is an SEM image of the composite positive electrode material provided in Comparative Example 11 of the present application;

[0020] Figure 9 This is an SEM image of the composite positive electrode material provided in Comparative Example 15 of the present application;

[0021] Figure 10 This is an SEM image of the composite positive electrode material provided in Comparative Example 17 of the present application;

[0022] Figure 11 This is an SEM image of the composite positive electrode material provided in Comparative Example 1 of this application;

[0023] Figure 12 This is an SEM image of the composite positive electrode material provided in Comparative Example 3 of this application;

[0024] Figure 13 XRD diffraction patterns of the composite positive electrode materials provided in Comparative Example 1, Example 1, Example 4, and Example 7 of the present application;

[0025] Figure 14 The first charge and discharge curves of the composite positive electrode materials provided in Comparative Examples 10, 7, and 17 of the present application at a rate of 0.1C;

[0026] Figure 15 The first charge and discharge curve of the composite positive electrode material provided in Comparative Example 1, Example 1, Example 4, and Example 7 of this application at a rate of 0.1C;

[0027] Figure 16 This is a graph showing the cycling performance of the composite cathode materials provided in Comparative Example 1, Example 1, Example 4, and Example 7 of the present application at a 1C rate;

[0028] Figure 17 This is a rate performance diagram of the composite positive electrode material provided in Comparative Example 1, Example 1, Example 4, and Example 7 of the present application at a voltage of 2.5-4.5V and a temperature of 0.1-10C. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] In the embodiments of the present application, Y, as one of the rare earth elements, has a large ionic radius and a strong affinity for oxygen. Ta is an important transition metal with an ionic radius between that of Mn and Fe. Ta in a high oxidation state forms a strong Ta-O bond with O, which can stabilize the crystal lattice. Y and Ta doping can improve the electrochemical properties of the material. By introducing Y and Ta elements into the material, its electronic structure can be changed, the electronic conductivity can be improved, and thus the electrochemical activity of the material can be enhanced. The high-temperature solid-phase carbon thermal reduction method has low cost and a simple preparation process. First, the lithium source, phosphorus source, iron source, and manganese source are mixed and dispersed, and then high-temperature sintering is performed to form the LFMP material. In addition, the material powder is subjected to repeated extrusion deformation and crushing through ball milling to achieve uniform mixing at the atomic level between the elements. The Y and Ta-doped modified LMFP / C positive electrode material synthesized by the high-temperature solid-phase carbon thermal reduction method exhibits excellent electrochemical performance. The application of this material in lithium-ion batteries is of great significance for promoting the development and commercialization of lithium-ion battery technology. Based on this, the present invention develops a method for preparing Y and Ta doped LMFP / C positive electrode materials by ball milling-high temperature solid phase carbothermal reduction sintering.

[0031] Specifically, the preparation method of the LMFP / C positive electrode material provided in the embodiment of the present application includes:

[0032] The lithium source, manganese source, iron source, phosphorus source, carbon source and doping source are sequentially subjected to dry grinding and wet grinding, and then dried and ball milled to obtain a powder precursor; wherein the doping source is a yttrium source and / or a tantalum source. When only the yttrium source is involved, the Y 3+ :PO4 3- The molar ratio of Ta is 0.1; when only tantalum source is involved, 5+ :PO4 3- The molar ratio of Y is 0.1; when both yttrium source and tantalum source are involved, 3+ and Ta5+ :PO4 3- The molar ratio is controlled within the range of 0.2-0.3;

[0033] Under an inert gas atmosphere, the powder precursor is heated to 350°C at a heating rate of 2-5°C / min for heat preservation and reaction, and is heated to 650-750°C at a heating rate of 3-5°C / min for heat preservation and reaction, and is cooled and ground to obtain a composite positive electrode material.

[0034] Preferably, the carbon source is C6H2O in a mass ratio of (10-20): (10-20): 1. 12 It is composed of O6, β-CD and NW-CNT.

[0035] Preferably, the amount of the carbon source is 10%-20% by mass of the total raw materials.

[0036] Preferably, the yttrium source is one of yttrium carbonate, yttrium nitrate and yttrium oxide.

[0037] Preferably, the tantalum source is tantalum oxide.

[0038] Preferably, the step of sequentially dry-grinding and wet-grinding the lithium source, manganese source, iron source, phosphorus source, carbon source, and dopant source, and then drying and ball-milling the mixture to obtain a powder precursor comprises:

[0039] The lithium source, manganese source, iron source, phosphorus source, carbon source and doping source are dry-ground for 0.5 hours, and then alcohol is added for wet-ground for 2 hours. The mixture is dried and ball-milled to obtain a powder precursor.

[0040] Preferably, the step of heating the powder precursor to 350° C. at a heating rate of 2-5° C. / min for heat preservation reaction and heating to 650-750° C. at a heating rate of 3-5° C. / min for heat preservation reaction under an inert gas atmosphere, cooling and grinding to obtain a composite positive electrode material comprises:

[0041] Under an inert gas atmosphere, the powder precursor is heated to 350°C at a heating rate of 2-5°C / min and kept warm for 5 hours, and then heated to 650-750°C at a heating rate of 3-5°C / min and kept warm for 10-12 hours. After cooling and grinding, a composite positive electrode material is obtained.

[0042] Preferably, according to Li + :Mn 2+ :Fe 3+ :PO4 3- The lithium source, manganese source, iron source and phosphorus source were weighed in a molar ratio of 1:(0.71-0.75):0.25:1.

[0043] The following examples describe in detail the preparation and application of the composite cathode material of the present application. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are commercially available unless otherwise specified.

[0044] Example 1

[0045] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y2O3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.) were weighed in a molar ratio of 1:0.74:0.25:1:0.1. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.). The above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0046] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 650°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY composite cathode material.

[0047] Example 2

[0048] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y2(CO3)3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.) were weighed in a molar ratio of 1:0.74:0.25:1:0.1. In addition, a carbon source C6H 12O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.). The above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0049] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 650°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY composite cathode material.

[0050] Example 3

[0051] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Ta 5+ The molar ratio is 1:0.74:0.25:1:0.1, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Scientific Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) are weighed respectively. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT:=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0052] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 750°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / C-Ta composite cathode material.

[0053] Example 4

[0054] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+The molar ratio was 1:0.73:0.25:1:0.1:0.1, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Scientific Co., Ltd.) and Y2(CO3) (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed respectively. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0055] The powder precursor was first dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min for 5 hours in the first stage. In the second stage, it was heated to 700°C at 3°C / min and held for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0056] Example 5

[0057] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+ The molar ratio was 1:0.73:0.25:1:0.1:0.1, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y(NO3)3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed respectively. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=10:10:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0058] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 750°C at 3°C / min and held for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0059] Example 6

[0060] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y2O3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed in a molar ratio of 1:0.73:0.25:1:0.1:0.1, and a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0061] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 5°C / min for 5 hours in the first stage. In the second stage, the product was heated to 700°C at 5°C / min for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0062] Example 7

[0063] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y(NO3)3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed in a molar ratio of 1:0.72:0.25:1:0.1:0.2, and a carbon source C6H 12 O6:β-CD:NW-CNT=10:10:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0064] The powder precursor was first dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min for 5 hours in the first stage. In the second stage, it was heated to 700°C at 3°C / min and held for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0065] Example 8

[0066] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y(NO3)3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed in a molar ratio of 1:0.72:0.25:1:0.1:0.2, and a carbon source C6H 12 O6:β-CD:NW-CNT=10:10:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0067] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 650°C at 3°C / min and held for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0068] Example 9

[0069] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y2(CO3)3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed in a molar ratio of 1:0.72:0.25:1:0.1:0.2, and a carbon source C6H 12 O6:β-CD=1:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball mill jar and ball milled by a high-speed vibration ball mill.

[0070] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 5°C / min for 5 hours in the first stage. In the second stage, the product was heated to 700°C at 5°C / min for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0071] Example 10

[0072] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y2O3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed in a molar ratio of 1:0.71:0.25:1:0.1:0.3. In addition, a carbon source C6H 12 O6:β-CD=1:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball mill jar and ball milled by a high-speed vibration ball mill.

[0073] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 5°C / min for 5 hours in the first stage. In the second stage, the product was heated to 700°C at 5°C / min for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0074] Comparative Example 1

[0075] Press Li + :Mn 2+ :Fe 3+ :PO4 3- The molar ratio was 1:0.75:0.25:1, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Scientific Co., Ltd.) were weighed respectively. In addition, a carbon source C6H 12 O6 (analytical grade, Xilong Chemical Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled by a high-speed vibration ball mill.

[0076] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min for 5 hours in the first stage. In the second stage, the product was heated to 650°C at 3°C / min for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / C composite cathode material.

[0077] Comparative Example 2

[0078] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y2O3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.) were weighed in a molar ratio of 1:0.74:0.25:1:0.1. In addition, a carbon source C6H 12 O6 (analytical grade, Xilong Chemical Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled by a high-speed vibration ball mill.

[0079] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 650°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY composite cathode material.

[0080] Comparative Example 3

[0081] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y2O3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.) were weighed in a molar ratio of 1:0.74:0.25:1:0.1. In addition, a carbon source C6H 12 O6: β-CD: NW-CNT = 1:1:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0082] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 650°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY composite cathode material.

[0083] Comparative Example 4

[0084] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y2O3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.) were weighed in a molar ratio of 1:0.74:0.25:1:0.1. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.). The above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0085] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 10°C / min for 5 hours in the first stage. In the second stage, the product was heated to 650°C at 10°C / min for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY composite cathode material.

[0086] Comparative Example 5

[0087] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and (Y2(CO3)3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.) were weighed in a molar ratio of 1:0.73:0.25:1:0.2, and a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.). The above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0088] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 650°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY composite cathode material.

[0089] Comparative Example 6

[0090] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and YPO4 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.) were weighed in a molar ratio of 1:0.74:0.25:1:0.1. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.). The above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0091] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 650°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY composite cathode material.

[0092] Comparative Example 7

[0093] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and (Y2(CO3)3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.) were weighed in a molar ratio of 1:0.74:0.25:1:0.1. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.). The above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0094] The powder precursor was first dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then removed and placed in a tube furnace under an inert gas atmosphere. The powder was first heated to 350°C at a heating rate of 2°C / min and held for 5 hours. In the second stage, the powder was heated to 800°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY composite cathode material.

[0095] Comparative Example 8

[0096] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Ta 5+The molar ratio is 1:0.74:0.25:1:0.1, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Scientific Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) are weighed respectively. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT:=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0097] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 750°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / C-Ta composite cathode material.

[0098] Comparative Example 9

[0099] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Ta 5+ The molar ratio is 1:0.73:0.25:1:0.2, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Scientific Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) are weighed respectively. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT:=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0100] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 750°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / C-Ta composite cathode material.

[0101] Comparative Example 10

[0102] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Ta 5+ The molar ratio is 1:0.74:0.25:1:0.1, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Scientific Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) are weighed respectively. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT:=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0103] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C for 5 hours in the first stage. In the second stage, the product was heated to 800°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / C-Ta composite cathode material.

[0104] Comparative Example 11

[0105] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Ta 5+The molar ratio is 1:0.74:0.25:1:0.1, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Scientific Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) are weighed respectively. In addition, a carbon source C6H 12 O6 (analytical grade, Xilong Chemical Co., Ltd., analytical grade), the above raw materials were transferred to an agate ball milling jar and ball milled by a high-speed vibration ball mill.

[0106] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 750°C at 3°C / min and held for 10 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / C-Ta composite cathode material.

[0107] Comparative Example 12

[0108] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Scientific Co., Ltd.) and Y2(CO3) (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed in a molar ratio of 1:0.73:0.25:1:0.1:0.1 respectively. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0109] The powder precursor was first dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min for 5 hours in the first stage. In the second stage, it was heated to 700°C at 3°C / min and held for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0110] Comparative Example 13

[0111] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Scientific Co., Ltd.) and Y2(SO4)3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed in a molar ratio of 1:0.73:0.25:1:0.1:0.1, and a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0112] The powder precursor was first dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min for 5 hours in the first stage. In the second stage, it was heated to 700°C at 3°C / min and held for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0113] Comparative Example 14

[0114] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+The molar ratio was 1:0.73:0.25:1:0.1:0.1, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Scientific Co., Ltd.) and Y2(CO3) (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed respectively. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0115] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated in a tube furnace under an inert gas atmosphere at a heating rate of 2°C / min to 350°C in the first stage and held for 5 hours. In the second stage, the product was heated to 700°C at 3°C / min and held for 15 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0116] Comparative Example 15

[0117] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+ The molar ratio was 1:0.73:0.25:1:0.1:0.1, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y(NO3)3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed respectively. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=10:10:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0118] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 10°C / min for 5 hours in the first stage. In the second stage, the product was heated to 750°C at 10°C / min for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0119] Comparative Example 16

[0120] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+ Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y2O3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed in a molar ratio of 1:0.73:0.25:1:0.1:0.1, and a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0121] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 5°C / min for 5 hours in the first stage. In the second stage, the product was heated to 700°C at 5°C / min for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0122] Comparative Example 17

[0123] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and Y2O3 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed in a molar ratio of 1:0.70:0.25:1:0.1:0.4. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0124] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 5°C / min for 5 hours in the first stage. In the second stage, the product was heated to 700°C at 5°C / min for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0125] Comparative Example 18

[0126] Press Li + :Mn 2+ :Fe 3+ :PO4 3- :Y 3+ :Ta 5+ The molar ratio was 1:0.73:0.25:1:0.1:0.1, and Li2CO3 (analytical grade, Xilong Chemical Co., Ltd.), Mn2CO3 (analytical grade, Xilong Chemical Co., Ltd.), FePO4·2H2O (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), NH4H2PO4 (analytical grade, Xilong Science Co., Ltd.) and YPO4 (analytical grade, Shanghai Yien Chemical Technology Co., Ltd.), Ta2O5 (analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.) were weighed respectively. In addition, a carbon source C6H 12 O6:β-CD:NW-CNT=20:20:1 (analytical grade, Xilong Chemical Co., Ltd., analytical grade, Aladdin Reagent (Shanghai) Co., Ltd.), the above raw materials were transferred to an agate ball milling jar and ball milled using a high-speed vibration ball mill.

[0127] The powder precursor was dry-milled for 0.5 hours, then wet-milled with alcohol for 2 hours. The product was then transferred to a high-temperature oven and dried for 12 hours. The powder precursor, which had been ball-milled for 0.5 hours, was then heated to 350°C in a tube furnace under an inert gas atmosphere at a heating rate of 5°C / min for 5 hours in the first stage. In the second stage, the product was heated to 700°C at 5°C / min for 12 hours. The product was then cooled naturally to room temperature and ground for 10-20 minutes to obtain the LMFP / CY-Ta composite cathode material.

[0128] First, a field emission scanning electron microscope (FESEM, SU5000) was used to observe the micromorphology of the composite cathode material samples prepared according to the methods of Examples 3, 4, 6, 7, 8 and Comparative Examples 1, 3, 9, 10, 11, 15, and 17. Figure 1-12 ) It can be seen that the composite cathode materials prepared by the method of the present application are composed of irregular nanoparticles, wherein Figure 1 The composite positive electrode material prepared by the method of Example 4 has the best dispersion between particles.

[0129] Furthermore, the crystal structures of the composite cathode material samples prepared according to the methods of Example 1, Example 4, Example 7, and Comparative Example 1 were characterized using an X-ray diffractometer within the radiation range of 2θ = 10° to 80°. The characterization results are shown in FIG. Figure 13 As shown, the test spectra of the two samples both have a Pnma62 orthorhombic space group structure, and the diffraction peaks can correspond to the LMFP (COD#2300355) standard card, without other miscellaneous diffraction peaks.

[0130] Furthermore, the composite cathode materials prepared in Examples 1-10 and Comparative Examples 1-18 were assembled into lithium-ion batteries according to the following method: 0.2 g of the composite cathode material synthesized above, 0.025 g of a PVDF binder, and 0.025 g of a Ketjen black conductive agent were weighed in a weight ratio of 8:1:1. An appropriate amount of NMP solvent was added dropwise to prepare a slurry. The slurry was stirred for 5 hours. The slurry was then coated on aluminum foil, dried, and cut into 12 mm electrode discs. The resulting discs were then assembled into CR2032 button cells for electrochemical performance testing. The discharge capacity test results at 0.1 C are shown in Table 1-2.

[0131] Table 1

[0132] Discharge capacity at 0.1C (mAh / g) Example 1 158.64 Example 2 156.82 Example 3 157.22 Example 4 165.02 Example 5 159.86 Example 6 160.21 Example 7 161.2 Example 8 160.46 Example 9 162.08 Example 10 159.26

[0133] Table 2

[0134]

[0135]

[0136] At room temperature, constant current charge and discharge tests were performed on the composite cathode material samples prepared according to Examples 1, 4, 7 and Comparative Example 1 within an operating voltage range of 2.5-4.5 V using a CT-4000 Xinwei battery testing system.

[0137] Figure 14 、 Figure 15 、 Figure 16 、 Figure 17 The first charge and discharge curves of the composite positive electrode materials at a rate of 0.1C, the cycle performance diagram at a rate of 1C, and the rate performance diagram of 0.1-10C are obtained according to Examples 1, 4, and 7 and Comparative Examples 1, 7, 10, and 17 respectively.

[0138] observe Figure 14 The composite cathode materials prepared in Comparative Examples 10, 7, and 17 have different electrochemical properties, and the first discharge specific capacities are 138.56 mAh g -1 、142.23mAh·g -1 、151.24mAh·g -1 .

[0139] observe Figure 15 The composite cathode materials prepared in Comparative Example 1, Example 1, Example 4, and Example 7 have different electrochemical properties, and the first discharge specific capacity is 150.41 mAh·g -1 、158.64mAh·g -1 、165.2mAh·g -1 、159.8mAh·g -1 Among them, Example 4 has the highest initial discharge specific capacity.

[0140] observe Figure 16 From the cycle performance diagram at 1C, it can be seen that the initial specific capacity of Example 4 is 140.53 mAh·g -1 , the capacity retention rate is 94.76% after 400 cycles, showing excellent cycle stability.

[0141] observe Figure 17 It can be seen that Example 4 has the most stable and outstanding rate performance, and can still maintain 89.8 mAh g at a rate of 10C. -1 The reversible specific capacity is 1000W, and there is no capacity decay when the rate returns to 0.1C. This shows that the lithium-ion battery assembled with the positive electrode material prepared in Comparative Example 6 has good stability. In summary, the electrochemical performance of the composite positive electrode material prepared in Example 4 is superior to that of the composite positive electrode materials prepared in Comparative Example 1, Example 1, Example 4, and Example 7.

[0142] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0143] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a composite positive electrode material, characterized in that: include: The lithium source, manganese source, iron source, phosphorus source, carbon source and doping source are sequentially subjected to dry grinding and wet grinding, and then dried and ball milled to obtain a powder precursor; wherein the doping source is a yttrium source and / or a tantalum source. When only the yttrium source is involved, the Y 3+ :PO4 3- The molar ratio of Ta is 0.1; when only tantalum source is involved, 5+ :PO4 3- The molar ratio of Y is 0.1; when both yttrium source and tantalum source are involved, 3+ and Ta 5+ :PO4 3- The molar ratio is controlled within the range of 0.2-0.3; Under an inert gas atmosphere, the powder precursor is heated to 350°C at a heating rate of 2-5°C / min for heat preservation and reaction, and is heated to 650-750°C at a heating rate of 3-5°C / min for heat preservation and reaction, and is cooled and ground to obtain a composite positive electrode material.

2. The method for preparing a composite positive electrode material according to claim 1, wherein: The carbon source is C6H2O in a mass ratio of (10-20): (10-20):

1. 12 It is composed of O6, β-CD and NW-CNT.

3. The method for preparing a composite positive electrode material according to claim 1, wherein: The amount of the carbon source used is 10%-20% of the total raw material mass ratio.

4. The method for preparing a composite cathode material according to claim 1, wherein: The yttrium source is one of yttrium carbonate, yttrium nitrate and yttrium oxide.

5. The method for preparing a composite positive electrode material according to claim 1, wherein: The tantalum source is tantalum oxide.

6. The method for preparing a composite cathode material according to claim 1, wherein: The step of sequentially dry-grinding and wet-grinding the lithium source, manganese source, iron source, phosphorus source, carbon source, and doping source, and then drying and ball-milling the mixture to obtain a powder precursor comprises: The lithium source, manganese source, iron source, phosphorus source, carbon source and doping source are dry-ground for 0.5 hours, and then alcohol is added for wet-ground for 2 hours. The mixture is dried and ball-milled to obtain a powder precursor.

7. The method for preparing a composite positive electrode material according to claim 1, wherein: The steps of heating the powder precursor to 350° C. at a heating rate of 2-5° C. / min for heat preservation reaction and heating to 650-750° C. at a heating rate of 3-5° C. / min for heat preservation reaction under an inert gas atmosphere, cooling and grinding to obtain a composite positive electrode material include: Under an inert gas atmosphere, the powder precursor is heated to 350°C at a heating rate of 2-5°C / min and kept warm for 5 hours, and then heated to 650-750°C at a heating rate of 3-5°C / min and kept warm for 10-12 hours. After cooling and grinding, a composite positive electrode material is obtained.

8. The method for preparing a composite cathode material according to claim 1, wherein: Press Li + :Mn 2+ :Fe 3+ :PO4 3- The lithium source, manganese source, iron source and phosphorus source were weighed in a molar ratio of 1:(0.71-0.75):0.25:

1.

9. A composite positive electrode material, characterized in that The composite positive electrode material is prepared by the method for preparing the composite positive electrode material according to any one of claims 1 to 8.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the composite positive electrode material according to claim 9.

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