A high energy density and high safety lithium ion battery positive electrode material and preparation method thereof

Abstract

The present invention relates to a high-energy-density and high-safety lithium-ion battery positive electrode material and a preparation method thereof. A modified eight-series ternary material is used as a positive electrode active material to prepare a CFx positive electrode sheet with high volume energy density. Specifically, the eight-series ternary material is mixed with an oxide, and the modified eight-series ternary material is obtained after sintering. The exothermic temperature of the whole material can be reduced by modifying the eight-series ternary material, and the coating of the oxide isolates the contact between the electrolyte and the electrode material, further improving the safety performance of the electrode material; the prepared battery has safety and stability, the equipment required for preparation is simple, the preparation process is controllable, and manpower and material resources are saved.

Description

Technical Field

[0001] The present invention belongs to the field of lithium ion batteries, and in particular relates to a lithium ion battery positive electrode material with high energy density and high safety and a preparation method thereof. Background Art

[0002] With the advancement of technology and the development of society, lithium-ion batteries have been widely used in both military and civilian fields due to their ease of use, high specific energy and long cycle life. In particular, ternary cathode materials have been widely used in new energy vehicles, electric bicycles, power tools, energy storage, drones, and smart wearable devices due to their high energy density, good cycle performance, fast charge and discharge performance and high temperature resistance, and have therefore been receiving worldwide attention. However, the safety and stability of this material need to be improved during the charging and discharging process, especially the safety of high-nickel materials such as 811, which is an important factor hindering its application. In order to further improve the safety of ternary high-nickel materials and apply them to power-consuming devices with strict safety requirements such as electric manned tools and smart wearable devices, the safety performance of the battery needs to be further enhanced. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a high energy density and high safety lithium ion battery positive electrode material and a preparation method thereof.

[0004] The technical solution adopted by the present invention is: a method for preparing a positive electrode material for a lithium-ion battery with high energy density and high safety, wherein eight series ternary materials are mixed with oxides and sintered, added to the positive electrode slurry, and coated on an electrode sheet to obtain a positive electrode for a lithium-ion battery.

[0005] Preferably, the oxide is a mixture of one or more of tungsten oxide, zirconium oxide, titanium oxide and aluminum oxide.

[0006] Preferably, 1-3% by mass of oxide is mixed with the eight-series ternary material.

[0007] Preferably, the eight-series ternary material is mixed with the oxide and sintered in an oxygen atmosphere at 200-500° C. for 1-5 hours.

[0008] A lithium-ion battery positive electrode prepared by a method for preparing a lithium-ion battery positive electrode material with high energy density and high safety.

[0009] A lithium ion battery comprises a lithium ion battery positive electrode.

[0010] The advantages and positive effects of the present invention are as follows: the eight-series ternary materials are modified by adding oxides to prepare the positive electrode of the lithium-ion battery, and the oxide coating isolates the contact between the electrolyte and the electrode material, thereby further improving the safety performance of the electrode material; the prepared battery has safety and stability, the equipment required for preparation is simple, the preparation process is controllable, and manpower and material resources are saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a discharge curve diagram of the ternary 811 of Example 1 of the present invention;

[0012] Figure 2 This is a DSC test diagram of Example 1 of the present invention;

[0013] Figure 3 This is a battery acupuncture diagram of Example 1 of the present invention. DETAILED DESCRIPTION

[0014] The embodiments of the present invention are described below with reference to the accompanying drawings.

[0015] The present invention relates to a high-energy-density and high-safety lithium-ion battery positive electrode material and a preparation method thereof, wherein a modified eight-series ternary material is used as a positive electrode active material to prepare a CFx positive electrode sheet with high volume energy density. Specifically, the eight-series ternary material is mixed with an oxide, and the modified eight-series ternary material is obtained after sintering. By modifying the eight-series ternary material, the exothermic temperature and heat release of the whole machine material can be reduced, thereby improving the safety of the battery.

[0016] Eight-series ternary materials refer to materials with a ratio of nickel, cobalt and manganese of 8:1:1, mainly including nickel cobalt manganese oxide positive electrode materials and lithium iron phosphate positive electrode materials. Compared with conventional ternary materials, eight-series ternary materials have higher energy density. The eight-series ternary materials are evenly mixed with oxides, with an oxide content of 1-3%, and sintered at 200-500℃ oxygen atmosphere for 1-5h to obtain modified eight-series ternary materials. Further, it is mixed with PTFE and conductive agent SP to prepare positive electrode slurry, and further prepared to obtain a high energy density and high safety lithium-ion battery positive electrode. The oxide is one or more oxides such as tungsten oxide, zirconium oxide, titanium oxide, aluminum oxide, etc. that have a coating effect on the positive electrode material.

[0017] A high nickel material with high electrochemical capacity is used as a matrix in an organic system electrolyte, and the oxide is evenly mixed, and the oxide is tightly coated on the surface of the positive electrode material by heating in an oxygen atmosphere. This method can maintain the good safety performance of the ternary positive electrode material without affecting the high energy density of the material. At the same time, the conductive oxide has good conductivity, which improves the conductivity between the materials. At the same time, the oxide coating isolates the contact between the electrolyte and the electrode material, further improving the safety performance of the electrode material.

[0018] The scheme of the present invention is described below in conjunction with the accompanying drawings, wherein the experimental methods without specific operating steps are all carried out in accordance with the corresponding product instructions, and the instruments, reagents, and consumables used in the examples can all be purchased from commercial companies unless otherwise specified.

[0019] Example 1

[0020] 10g NCM811 and 0.3g tungsten oxide were mixed evenly, heated at 300℃ in oxygen atmosphere for 3 hours, and cooled naturally. The composite positive electrode, conductive agent SP, and PTFE were mixed evenly in a ratio of 95:2.5:2.5, coated on aluminum foil, and after drying, a 20mm diameter pole piece was punched out from the pole piece, and it was loaded into the battery shell of CR2430 together with the diaphragm and 0.6mm thick lithium sheet, and the basic electrolyte was added and sealed.

[0021] The prepared battery was tested and the results Figure 1 As shown, the charge and discharge current is 20mA / g, and the cut-off voltage is 2.5-4.3V. The capacity is 228mAh / g. DSC test is as follows Figure 2 As shown, the exothermic temperature is 240°C and the exothermic heat is 1.413 mW / mg.

[0022] Example 2

[0023] Mix 10g NCM811 and 0.1g tungsten oxide evenly, heat at 300℃ in oxygen atmosphere for 3 hours, and cool naturally. Mix the composite positive electrode, conductive agent SP, and PTFE in a ratio of 95:2.5:2.5, apply it on aluminum foil, and after drying, punch out a 20mm diameter pole piece from the pole piece, put it into the CR2430 battery shell together with the diaphragm and 0.6mm thick lithium sheet, add basic electrolyte, and seal it. Charge and discharge at a current of 20mA / g, with a cut-off voltage of 2.5-4.3V. Capacity 230mAh / g. DSC test exothermic temperature 230℃, heat release 5.441mW / mg.

[0024] Example 3

[0025] Mix 10g NCM811 and 0.3g tungsten oxide evenly, heat at 500℃ in oxygen atmosphere for 3 hours, and cool naturally. Mix the composite positive electrode, conductive agent SP, and PTFE in a ratio of 95:2.5:2.5, apply it on aluminum foil, and after drying, punch out a 20mm diameter pole piece from the pole piece, put it into the CR2430 battery shell together with the diaphragm and 0.6mm thick lithium sheet, add basic electrolyte, and seal it. Charge and discharge at a current of 20mA / g, with a cut-off voltage of 2.5-4.3V. Capacity 223mAh / g. DSC test exothermic temperature 238℃, heat release 1.625mW / mg.

[0026] Example 4

[0027] Mix 10g NCM811 and 0.3g tungsten oxide evenly, heat at 200℃ in oxygen atmosphere for 3 hours, and cool naturally. Mix the composite positive electrode, conductive agent SP, and PTFE in a ratio of 95:2.5:2.5, apply it on aluminum foil, dry it, punch out a 20mm diameter pole piece from the pole piece, put it into the CR2430 battery shell together with the diaphragm and 0.6mm thick lithium sheet, add basic electrolyte, and seal it. Charge and discharge at 20mA / g current, cut-off voltage 2.5-4.3V. Capacity 221mAh / g. DSC test exothermic temperature 240℃, heat release 1.535mW / mg.

[0028] Example 5

[0029] Mix 10g NCM811 and 0.3g zirconium oxide evenly, heat at 300℃ in oxygen atmosphere for 1 hour, and cool naturally. Mix the composite positive electrode, conductive agent SP, and PTFE in a ratio of 95:2.5:2.5, apply it on aluminum foil, and after drying, punch out a 20mm diameter pole piece from the pole piece, put it into the CR2430 battery shell together with the diaphragm and 0.6mm thick lithium sheet, add basic electrolyte, and seal it. Charge and discharge at a current of 20mA / g, with a cut-off voltage of 2.5-4.3V. Capacity 225mAh / g. DSC test exothermic temperature 240℃, heat release 1.535mW / mg.

[0030] Example 6

[0031] Mix 10g NCM811 and 0.3g zirconium oxide evenly, heat at 300℃ in oxygen atmosphere for 5 hours, and cool naturally. Mix the composite positive electrode, conductive agent SP, and PTFE in a ratio of 95:2.5:2.5, apply it on aluminum foil, and after drying, punch out a 20mm diameter pole piece from the pole piece, put it into the CR2430 battery shell together with the diaphragm and 0.6mm thick lithium sheet, add basic electrolyte, and seal it. Charge and discharge at a current of 20mA / g, with a cut-off voltage of 2.5-4.3V. Capacity 223mAh / g. DSC test exothermic temperature 240℃, heat release 1.565mW / mg.

[0032] Example 7

[0033] The positive electrode material obtained in Example 1 was enlarged to produce a 280Wh / Kg 1064143 soft-pack battery. It was charged to 4.3V and punctured without catching fire or exploding.

[0034] Comparative Example 1

[0035] The original 811, conductive agent SP, and PTFE were mixed evenly in a ratio of 95:2.5:2.5, coated on aluminum foil, and after drying, a 20 mm diameter pole piece was punched out from the pole piece, and loaded into the CR2430 battery shell together with the diaphragm and 0.6 mm thick lithium sheet, and basic electrolyte was added and sealed. The charge and discharge were performed at a current of 20 mA / g, and the cut-off voltage was 2.5-4.3 V. The DSC test exothermic temperature was 220 ° C, and the heat release was 11.0 mW / mg.

[0036] According to the above method, a 1064143 type soft-pack battery with an energy density of 280Wh / Kg was made, charged to 4.3V, punctured, and caught fire and exploded.

[0037] From the above data comparison, it can be seen that compared with the original NCM811 material in Comparative Example 1, the positive electrode prepared by adding oxide in Examples 1-6 has significantly reduced exothermic temperature and exothermic collar of the ternary material. After further making it into a battery, it can have good safety performance and can pass the needle puncture test.

[0038] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a positive electrode material for a lithium-ion battery with high energy density and high safety, characterized in that: The eight-series ternary material is mixed with oxides and sintered, added into the positive electrode slurry, and coated onto the electrode sheet to obtain the positive electrode of the lithium-ion battery.

2. The method for preparing a positive electrode material for a lithium-ion battery with high energy density and high safety according to claim 1, characterized in that: The oxide is a mixture of one or more of tungsten oxide, zirconium oxide, titanium oxide and aluminum oxide.

3. The method for preparing a positive electrode material for a lithium-ion battery with high energy density and high safety according to claim 2, characterized in that: 1-3% by mass of oxide is mixed with the eight-series ternary material.

4. The method for preparing a positive electrode material for a lithium-ion battery with high energy density and high safety according to claim 1, characterized in that: The eight series ternary materials are mixed with oxides and sintered in an oxygen atmosphere at 200-500°C for 1-5 hours.

5. A lithium-ion battery positive electrode prepared by the method for preparing a lithium-ion battery positive electrode material with high energy density and high safety as described in any one of claims 1 to 4.

6. A lithium ion battery, characterized in that: The lithium-ion battery positive electrode comprises the positive electrode of claim 5.

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