High-voltage composite positive electrode material for lithium ion battery and preparation method of high-voltage composite positive electrode material

Abstract

The invention belongs to the field of lithium ion battery raw materials, and particularly relates to a high-voltage composite positive electrode material for a lithium ion battery and a preparation method of the high-voltage composite positive electrode material. The composite positive electrode material is prepared from a high-voltage positive electrode material, a reducing material and a catalytic material, the method comprises the following steps: uniformly mixing a high-voltage positive electrode material and a catalytic material, and carrying out heat treatment to obtain a composite material of the positive electrode material and the catalytic material; and adding a reducing material, and carrying out heat treatment to obtain the high-voltage composite positive electrode material for the lithium ion battery. According to the method, the surface of the positive electrode material is subjected to catalytic material modification, so that the structural stability of the positive electrode material under high voltage can be improved; the reduction material is compounded on the surface of the catalytic material, free oxygen generated by the positive electrode material is fixed in situ, the bag expansion phenomenon of the battery is relieved, and the cycling stability and safety of the battery are further improved; the preparation process is simple, raw materials are cheap and easy to obtain, the production cost is low, and industrial production and popularization are easy.

Description

Technical Field

[0001] The invention belongs to the field of raw materials for lithium-ion batteries, and in particular relates to a high-voltage composite positive electrode material for lithium-ion batteries and a preparation method thereof. Background Art

[0002] With the rapid development of personal consumer electronics and electric vehicles, higher requirements are placed on lithium-ion batteries to achieve longer standby time and driving range: high energy density, long cycle life, and good safety. The use of high-gram capacity and high-voltage positive electrode materials is the most effective way to increase battery energy density. However, during the cycle process, high-gram capacity and high-voltage positive electrode materials are usually accompanied by changes in crystal structure, dissolution of transition metal ions, and precipitation of oxygen, which cause the material particles to break, decompose, and fall off, resulting in rapid attenuation of material capacity and safety issues. The positive electrode material is usually surface modified to inhibit the occurrence of irreversible changes, improve the structural stability of the material, and thus improve the cycle life and safety of the battery.

[0003] The present invention improves the structural stability of the high-voltage positive electrode material by modifying the surface of the high-voltage positive electrode material with a catalytic material, and on the other hand, utilizes the reduced material to adsorb the released oxygen to form a stable interface layer, thereby further improving the stability of the material, alleviating the battery bagging phenomenon, and thereby improving the cycle stability and safety of the battery. Summary of the invention

[0004] The purpose of the present invention is to solve the cycle stability and safety problems of high-voltage lithium-ion batteries and to provide a high-voltage composite positive electrode material for lithium-ion batteries and a preparation method thereof.

[0005] The idea of ​​the present invention is: on the one hand, catalytic materials are modified on the surface of high-voltage positive electrode materials to improve the structural stability of the positive electrode materials; on the other hand, reducing materials are composited on the surface of the catalytic materials, and the reducing materials are used to adsorb oxygen precipitated from the positive electrode materials to form a stable interface layer, thereby further improving the stability of the materials, alleviating the battery bag swelling phenomenon, and thereby improving the cycle stability and safety of the battery.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a high-voltage composite positive electrode material for a lithium-ion battery, wherein the composite positive electrode material is composed of a high-voltage positive electrode material, a reducing material and a catalytic material;

[0008] The high voltage positive electrode material includes at least one of lithium iron pyrophosphate material, lithium iron manganese pyrophosphate material, lithium manganese pyrophosphate material, lithium cobalt pyrophosphate material, lithium manganese oxide material, lithium nickel manganese oxide material, lithium cobalt oxide material, lithium nickel cobalt manganese oxide material, nickel cobalt aluminum oxide material, and lithium-rich oxide material;

[0009] The reducing material includes at least one of elemental sulfur, lithium sulfide, sodium sulfide, potassium sulfide, zinc sulfide, magnesium sulfide, ferrous sulfide, manganese sulfide, cobalt sulfide, nickel sulfide, elemental phosphorus, zinc phosphide, magnesium phosphide, iron phosphide, manganese phosphide, cobalt phosphide, and nickel phosphide;

[0010] The catalytic material includes at least one of ferrous oxide, manganese oxide, cobalt oxide, nickel oxide, carbon nanotubes, and graphene;

[0011] The molar proportions of the high voltage positive electrode material, the reducing material, and the catalytic material are 95-99 parts, 0.01-5 parts, and 0.01-1 parts, respectively;

[0012] The specific steps include:

[0013] Step 1: After the high voltage positive electrode material and the catalytic material are uniformly mixed in the above ratio, the composite material S1 is obtained after heat treatment at 300-600° C. in an inert gas atmosphere;

[0014] Step 2: Add reducing materials to the composite material S1 in the proportion, mix them evenly, and heat treat them at 100-300° C. under an inert gas atmosphere to obtain a high-voltage composite positive electrode material for lithium-ion batteries.

[0015] Preferably, the inert gas is nitrogen or argon.

[0016] Preferably, the heat treatment time of step 1 and step 2 is 0.5 to 10 hours.

[0017] Preferably, the lithium nickel cobalt manganese oxide material comprises LiNi 0.90 Co 0.05 Mn 0.05 O2.

[0018] Preferably, the lithium-rich oxide comprises a lithium-rich manganese-based material.

[0019] Furthermore, the lithium-rich manganese-based material includes Li 1.3 Ni 0.15 Co 0.2 Mn 0.65 O 2.3 .

[0020] In a second aspect, the present invention provides a high voltage composite positive electrode material prepared by the method described in the first aspect.

[0021] Preferably, the structure of the composite positive electrode material is as follows: the high voltage positive electrode material is inside the composite positive electrode material, and the reducing material and the catalytic material are coated and attached to the outside of the high voltage positive electrode material.

[0022] Furthermore, the coating thickness of the reducing material and the catalytic material is 1 to 10 nm.

[0023] In a third aspect, the present invention provides a use of the high-voltage composite positive electrode material described in the second aspect for preparing a lithium-ion battery, wherein the composite positive electrode material is used to prepare a positive electrode of a lithium-ion battery.

[0024] Beneficial effects of the present invention: The method prepares a high-voltage composite positive electrode material for lithium-ion batteries, which has the following advantages:

[0025] (1) Modifying the surface of the positive electrode material with a catalytic material can improve the structural stability of the positive electrode material under high voltage;

[0026] (2) Introducing reducing materials on the surface of the catalytic material to in-situ fix the free oxygen generated by the positive electrode material under high pressure to form a stable interface layer, alleviate the battery bagging phenomenon, and further improve the cycle stability and safety of the battery;

[0027] (3) The prepared high-voltage composite positive electrode material for lithium-ion batteries has a simple preparation process, low production cost, and is easy to promote industrial production;

[0028] (4) The prepared high-voltage composite positive electrode material for lithium-ion batteries has good adaptability to the existing lithium-ion battery preparation process, does not require major changes, and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 SEM image of the prepared high voltage composite cathode material DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and examples.

[0031] Example 1

[0032] The steps of preparing a high voltage composite positive electrode material for lithium ion batteries are as follows:

[0033] Step 1: Preparation of high voltage cathode material and catalytic material composite material

[0034] 0.1 mol of lithium nickel cobalt manganese oxide (LiNi 0.90 Co 0.05 Mn 0.05O2) and 0.01 mol of cobalt oxide are mixed evenly to make the cobalt oxide adhere to the surface of lithium nickel cobalt manganese oxide, and heat treated at 400°C for 3h in a nitrogen atmosphere to obtain a composite material of lithium nickel cobalt manganese oxide and cobalt oxide;

[0035] Step 2: Preparation of high voltage composite cathode materials for lithium-ion batteries

[0036] The prepared composite material of lithium nickel cobalt manganese oxide and cobalt oxide is evenly mixed with 0.03 mol of elemental phosphorus, and heat-treated at 110° C. for 3 hours to disperse the elemental phosphorus on the surface of the composite material of lithium nickel cobalt manganese oxide and cobalt oxide, thereby obtaining a high-voltage composite positive electrode material for lithium ion batteries.

[0037] The SEM image of the prepared high voltage composite cathode material is shown in Figure 1 As shown, the catalytic material and the reducing material are attached to the surface of the high voltage positive electrode material.

[0038] Example 2

[0039] The steps of preparing a high voltage composite positive electrode material for lithium ion batteries are as follows:

[0040] Step 1: Preparation of high voltage cathode material and catalytic material composite material

[0041] 0.1 mol of lithium-rich manganese-based material (Li 1.3 Ni 0.15 Co 0.2 Mn 0.65 O 2.3 ), 0.01 mol ferrous oxide and 0.01 mol graphene are mixed evenly, so that the ferrous oxide and graphene are attached to the surface of the lithium-rich manganese-based material, and heat-treated at 500° C. for 1 h under an argon atmosphere to obtain a composite material of the lithium-rich manganese-based material, ferrous oxide and graphene;

[0042] Step 2: Preparation of high voltage composite cathode materials for lithium-ion batteries

[0043] The prepared composite material of lithium-rich manganese-based material, ferrous oxide and graphene is evenly mixed with 0.03 mol of iron phosphide, and heat-treated at 260°C for 3 hours to disperse the iron phosphide on the surface of the composite material of lithium-rich manganese-based material, ferrous oxide and graphene, thereby obtaining a high-voltage composite positive electrode material for lithium-ion batteries.

[0044] The prepared high-voltage composite positive electrode material was used as the positive electrode to assemble a button-type lithium-ion battery. The constant current charge and discharge test was carried out at 0.1C in the voltage range of 2 to 4.8V. The first discharge specific capacity reached 310mAh / g, and the capacity retention rate after 200 cycles of constant current charge and discharge at 0.5C reached more than 92%, demonstrating excellent electrochemical performance.

Claims

1. A method for preparing a high voltage composite positive electrode material for a lithium ion battery, characterized in that: The composite positive electrode material is composed of a high voltage positive electrode material, a reducing material and a catalytic material; The high voltage positive electrode material includes at least one of lithium iron pyrophosphate material, lithium iron manganese pyrophosphate material, lithium manganese pyrophosphate material, lithium cobalt pyrophosphate material, lithium manganese oxide material, lithium nickel manganese oxide material, lithium cobalt oxide material, lithium nickel cobalt manganese oxide material, nickel cobalt aluminum oxide material, and lithium-rich oxide material; The reducing material includes at least one of elemental sulfur, lithium sulfide, sodium sulfide, potassium sulfide, zinc sulfide, magnesium sulfide, ferrous sulfide, manganese sulfide, cobalt sulfide, nickel sulfide, elemental phosphorus, zinc phosphide, magnesium phosphide, iron phosphide, manganese phosphide, cobalt phosphide, and nickel phosphide; The catalytic material includes at least one of ferrous oxide, manganese oxide, cobalt oxide, nickel oxide, carbon nanotubes, and graphene; The molar proportions of the high voltage positive electrode material, the reducing material, and the catalytic material are 95-99 parts, 0.01-5 parts, and 0.01-1 parts, respectively; The specific steps include: Step 1: After the high voltage positive electrode material and the catalytic material are uniformly mixed in the above ratio, the composite material S1 is obtained after heat treatment at 300-600° C. in an inert gas atmosphere; Step 2: Add reducing materials to the composite material S1 in the proportion, mix them evenly, and heat treat them at 100-300° C. under an inert gas atmosphere to obtain a high-voltage composite positive electrode material for lithium-ion batteries.

2. The method for preparing a high voltage composite positive electrode material for a lithium ion battery according to claim 1, characterized in that: The inert gas is nitrogen or argon.

3. The method for preparing a high voltage composite positive electrode material for a lithium ion battery according to claim 1, characterized in that: The heat treatment time of step 1 and step 2 is 0.5 to 10 hours.

4. The method for preparing a high voltage composite positive electrode material for a lithium ion battery according to claim 1, characterized in that: The lithium nickel cobalt manganese oxide material includes LiNi 0.90 Co 0.05 Mn 0.05 O2.

5. The method for preparing a high voltage composite positive electrode material for a lithium ion battery according to claim 1, characterized in that: The lithium-rich oxide includes a lithium-rich manganese-based material.

6. The method for preparing a high voltage composite positive electrode material for a lithium ion battery according to claim 5, characterized in that: The lithium-rich manganese-based material includes Li 1.3 Ni 0.15 Co 0.2 Mn 0.65 O 2.3 .

7. A high voltage composite positive electrode material prepared by the method according to any one of claims 1 to 6.

8. The high voltage composite positive electrode material according to claim 7, characterized in that: The structure of the composite positive electrode material is as follows: the high voltage positive electrode material is inside the composite positive electrode material, and the reducing material and the catalytic material are coated and attached to the outside of the high voltage positive electrode material.

9. The high voltage composite positive electrode material according to claim 8, characterized in that: The coating thickness of the reducing material and the catalytic material is 1 to 10 nm.

10. Use of the high voltage composite positive electrode material according to any one of claims 7 to 9 for preparing lithium ion batteries, characterized in that: The composite positive electrode material is used to prepare the positive electrode of a lithium ion battery.

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