阅读说明：本技术 高比能量锂离子电池及其制备方法 (High specific energy lithium ion battery and preparation method thereof ) 是由 葛超 王盈来 相佳媛 于 2020-03-20 设计创作，主要内容包括：本发明提供一种高比能量锂离子电池及其制备方法。一种高比能量锂离子电池包括正极和负极,正极包括正极活性物质、正极导电剂及正极粘接剂,负极包括负极活性物质、负极导电剂及负极粘接剂；正极活性物质为富锂锰基材料和镍钴锰三元材料的混合材料,负极活性物质为石墨材料和硅基材料的混合材料。(The invention provides a high-specific energy lithium ion battery and a preparation method thereof. A high specific energy lithium ion battery comprises a positive electrode and a negative electrode, wherein the positive electrode comprises a positive active material, a positive conductive agent and a positive adhesive, and the negative electrode comprises a negative active material, a negative conductive agent and a negative adhesive; the positive electrode active substance is a mixed material of a lithium-rich manganese-based material and a nickel-cobalt-manganese ternary material, and the negative electrode active substance is a mixed material of a graphite material and a silicon-based material.)

1. The high-specific-energy lithium ion battery is characterized by comprising a positive electrode and a negative electrode, wherein the positive electrode comprises a positive active material, a positive conductive agent and a positive adhesive, and the negative electrode comprises a negative active material, a negative conductive agent and a negative adhesive; the positive active substance is a mixed material of a lithium-rich manganese-based material and a nickel-cobalt-manganese ternary material, and the negative active substance is a mixed material of a graphite material and a silicon-based material.

2. The high specific energy lithium ion battery of claim 1, wherein the mass ratio of the lithium-rich manganese-based material to the nickel-cobalt-manganese ternary material in the mixed material of the lithium-rich manganese-based material and the nickel-cobalt-manganese ternary material is (0.1-10): 1; the mass ratio of the graphite material to the silicon-based material in the mixed material of the graphite material and the silicon-based material is (0.1-50): 1.

3. The high specific energy lithium ion battery of claim 2, wherein the mass ratio of the lithium-rich manganese-based material to the nickel-cobalt-manganese ternary material in the mixed material of the lithium-rich manganese-based material and the nickel-cobalt-manganese ternary material is (0.6-1.67):1, and the mass ratio of the graphite material to the silicon-based material in the mixed material of the graphite material and the silicon-based material is 24.28: 1.

4. The high specific energy lithium ion battery of claim 3, wherein the nickel cobalt manganese ternary material is formed from SnO₂And (4) targeted coating.

5. The high specific energy lithium ion battery according to any one of claims 1 to 4, wherein the positive electrode active material accounts for 95% or more by mass of the positive electrode, and the negative electrode active material accounts for 95% or more by mass of the negative electrode.

6. The high specific energy lithium ion battery of any one of claims 1 to 4, wherein the positive electrode conductive agent comprises particulate conductive carbon black having a particle size of 30-40nm and carbon nanotubes, and the negative electrode conductive agent comprises particulate conductive carbon black having a particle size of 30-40 nm.

7. A method of manufacturing a high specific energy lithium ion battery according to any of claims 1 to 6, comprising:

preparing a positive electrode: mixing the positive active substance, the positive conductive agent and the positive adhesive in proportion, uniformly stirring, coating on an aluminum foil, drying, rolling and slicing to obtain a positive electrode;

preparing a negative electrode: mixing and stirring a negative active material, a negative conductive agent and a negative adhesive uniformly according to a proportion, coating the mixture on a copper foil, drying the copper foil, and rolling and slicing the dried copper foil to obtain a negative electrode;

preparing a dry battery cell: preparing a dry battery cell by using the prepared negative electrode and the prepared positive electrode; and

and (5) preparing the battery.

8. The high specific energy lithium ion battery of claim 7, wherein the preparation of the dry cell comprises: and taking a polyethylene film as a diaphragm, stacking the anode, the diaphragm and the cathode in sequence, separating the anode and the cathode by the diaphragm, welding a tab on the outermost layer of the anode and the cathode to obtain the dry battery cell.

9. The high specific energy lithium ion battery of claim 8, wherein said polyethylene film is single coated with a ceramic material.

10. The high specific energy lithium ion battery of any of claims 8 to 9, wherein the preparing the battery comprises preparing an electrolyte and packaging the battery, wherein the preparing the electrolyte comprises: mixing and dissolving lithium hexafluorophosphate serving as lithium salt in a solvent with the mass ratio of ethylene carbonate, propylene carbonate and dimethyl carbonate being 1:1:1 to obtain electrolyte; the package of the battery includes: and injecting electrolyte, pre-sealing, standing, forming, secondary sealing, capacity grading and aging to obtain the high specific energy lithium ion battery.

Technical Field

The invention relates to the technical field of lithium ion batteries, in particular to a high-specific-energy lithium ion battery and a preparation method thereof.

Background

Among many cathode materials of lithium ion batteries, lithium-rich manganese-based materials are receiving increasing attention due to their high specific energy (> 250mAh/g), high potential (4.4V) and low price. The lithium-rich manganese-based material has the defects of low first charge-discharge efficiency, capacity attenuation caused by voltage attenuation, poor rate capability and the like, and the commercialization degree of the material is limited.

The negative electrode of a commercial lithium ion battery is generally made of graphite material, and the theoretical specific capacity of the negative electrode is only 372 mAh/g. The theoretical specific capacity of the graphite as the negative electrode material makes the graphite unable to alone play the big role of the new generation of negative electrode materials of lithium ion batteries. The silicon-based material severely limits its possibility of individual use due to excessive volume effects during its lithium intercalation.

Disclosure of Invention

The invention aims to provide a high-specific energy lithium ion battery and a preparation method thereof.

In order to solve the technical problems, the invention provides a high specific energy lithium ion battery, which comprises a positive electrode and a negative electrode, wherein the positive electrode comprises a positive active material, a positive conductive agent and a positive adhesive; the positive electrode active substance is a mixed material of a lithium-rich manganese-based material and a nickel-cobalt-manganese ternary material, and the negative electrode active substance is a mixed material of a graphite material and a silicon-based material.

Optionally, the mass ratio of the lithium-rich manganese-based material to the nickel-cobalt-manganese ternary material in the mixed material of the lithium-rich manganese-based material and the nickel-cobalt-manganese ternary material is (0.1-10):1, and the mass ratio of the graphite material to the silicon-based material in the mixed material of the graphite material and the silicon-based material is (0.1-50): 1.

Optionally, the nickel-cobalt-manganese ternary material is SnO₂And (4) targeted coating.

Optionally, the mass ratio of the lithium-rich manganese-based material to the nickel-cobalt-manganese ternary material in the mixed material of the lithium-rich manganese-based material and the nickel-cobalt-manganese ternary material is (0.6-1.67):1, and the mass ratio of the graphite material to the silicon-based material in the mixed material of the graphite material and the silicon-based material is 24.28: 1.

Optionally, the mass of the positive electrode active material in the positive electrode is more than 95%, and the mass of the negative electrode active material in the negative electrode is more than 95%.

Optionally, the positive electrode conductive agent comprises particle conductive carbon black with the particle size of 30-40nm and carbon nanotubes, and the negative electrode conductive agent comprises particle conductive carbon black with the particle size of 30-40 nm.

The invention also provides a preparation method for manufacturing the high-specific-energy lithium ion battery, which comprises the following steps:

preparing a positive electrode: mixing the positive active substance, the positive conductive agent and the positive adhesive in proportion, uniformly stirring, coating on an aluminum foil, drying, rolling and slicing to obtain a positive electrode;

preparing a negative electrode: mixing and stirring a negative active material, a negative conductive agent and a negative adhesive uniformly according to a proportion, coating the mixture on a copper foil, drying the copper foil, and rolling and slicing the dried copper foil to obtain a negative electrode;

preparing a dry battery cell: preparing a dry battery cell by using the prepared negative electrode and the prepared positive electrode; and

and (5) preparing the battery.

Optionally, the preparation of the dry cell includes: and taking a polyethylene film as a diaphragm, stacking the anode, the diaphragm and the cathode in sequence, separating the anode and the cathode by the diaphragm, welding a tab on the outermost layer of the anode and the cathode to obtain the dry battery cell.

Optionally, the polyethylene film is coated on one side with a ceramic material.

Optionally, the preparing the battery includes preparing an electrolyte and packaging the battery, and the preparing the electrolyte includes: mixing and dissolving lithium hexafluorophosphate serving as lithium salt in a solvent with the mass ratio of ethylene carbonate, propylene carbonate and dimethyl carbonate being 1:1:1 to obtain electrolyte; the package of the battery includes: and injecting electrolyte, pre-sealing, standing, forming, secondary sealing, capacity grading and aging to obtain the high-specific-energy lithium ion battery.

In conclusion, the positive electrode of the high-specific-energy lithium ion battery provided by the invention utilizes the relatively stable structural characteristic of the nickel-cobalt-manganese NCM ternary material and the higher specific capacity of the lithium-rich manganese-based material, and the mixed positive electrode material has the characteristics of high specific capacity and long cycle performance and overcomes the serious defect of voltage attenuation of the lithium-rich manganese-based material to a certain extent. Meanwhile, the silicon-based material is matched to be used together with the cathode of the cathode additive, so that the capacity is improved.

Detailed Description

The following examples are given to further illustrate the embodiments of the present invention. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.