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A kind of composite 3D current collector and its preparation and application

A current collector and 3D technology, which is applied in the field of composite 3D current collectors and current collectors for lithium secondary batteries, can solve problems such as inability to achieve directional deposition of lithium metal, low cycle efficiency, and safety issues

Active Publication Date: 2021-07-06
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First, the lithium dendrite problem, that is, the growth of lithium dendrites during the charge-discharge cycle of the battery can cause internal short circuits and serious safety issues in the battery, and it can also cause repeated damage to the SEI film to cause reactions between metal lithium and the electrolyte.
Second, the cycle efficiency is low. There are two reasons: the repeated damage and repair of the SEI film on the surface of lithium metal during charging and discharging, which consumes lithium metal and shortens the battery life; the generation of irreversible "dead lithium" will also reduce the lithium metal battery capacity
However, a single 3D current collector cannot realize the directional deposition of lithium metal, so lithium is easy to deposit on the surface of the 3D current collector during high-power charging and discharging, which cannot effectively inhibit the dendrite from piercing the separator, causing serious safety hazards.

Method used

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  • A kind of composite 3D current collector and its preparation and application
  • A kind of composite 3D current collector and its preparation and application
  • A kind of composite 3D current collector and its preparation and application

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] 0.4g CNTs were uniformly dispersed in the aqueous solution with a mass fraction of 5%. Add 16.5g of 2% sodium carboxymethyl cellulose aqueous solution, stir for 4 hours to mix evenly, then add 1.65g of 40% styrene-butadiene rubber aqueous solution, and stir for 0.5h to cause crosslinking reaction of the binder. The prepared slurry was evenly spread on the nickel foam, frozen with liquid nitrogen, and dried with a freeze dryer at -45°C for 10 h. The prepared precursor was then placed in a tube furnace and calcined at 900°C for 4 hours under argon gas to carbonize the polymer binder in the precursor to obtain a composite 3D current collector. The mass content of the carbon material in the composite 3D current collector is 1.2%, and the specific surface area of ​​the composite 3D current collector is 173cm 3 / g, the pore volume is 5cm 3 / g, the density is 7.3g / cm 3 .

[0037] The obtained composite 3D current collector was cut into discs with a diameter of 1.9 mm, and ...

Embodiment 2

[0039] Adopt the method of comparative example 2 to prepare LiFePO 4 Positive electrode, the composite 3D current collector of pre-deposited lithium in Example 1 is the negative electrode, celgard 2325 is the diaphragm, with 1mol / L LiPF 6 The solution of EC+DMC (volume ratio 1:1) is used as the electrolyte, and the CR2016 button battery is assembled, and the cycle performance charge and discharge test is carried out at a rate of 0.5C.

Embodiment 3

[0041]0.4g CNTs were uniformly dispersed in the aqueous solution with a mass fraction of 5%. Add 16.5g of 2% sodium carboxymethyl cellulose aqueous solution, stir for 4 hours to mix evenly, then add 1.65g of 40% styrene-butadiene rubber aqueous solution, and stir for 0.5h to cause crosslinking reaction of the binder. The prepared slurry was evenly spread on the nickel foam, frozen with liquid nitrogen, and dried with a freeze dryer at -45°C for 10 h. The prepared precursor was then placed in a tube furnace and calcined at 900°C for 4 hours under argon gas to carbonize the polymer binder in the precursor to obtain a composite 3D current collector. The mass content of the carbon material in the composite 3D current collector is 0.5%, and the specific surface area of ​​the composite 3D current collector is 82cm 3 / g, the pore volume is 1.2cm 3 / g, the density is 6.7g / cm 3 .

[0042] The obtained composite 3D current collector was cut into discs with a diameter of 1.9 mm, and ...

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Abstract

The invention relates to a composite 3D current collector and its preparation and application. The composite 3D current collector is prepared by a freeze-drying method with a porous conductive material as the 3D conductive skeleton and a lithium-philic carbon material as the internal filler; the prepared 3D The current collector has a high surface area and a large lithium storage space, which is beneficial to reduce the actual current density of lithium deposition and prevent lithium dendrites from piercing the separator; on the other hand, the introduction of lithium-friendly materials can achieve directional deposition of lithium metal and enhance the uniformity of deposition. The 3D current collector is used in the negative electrode collector of lithium metal batteries. Through the synergistic effect of the above two aspects, it can greatly improve the cycle stability of the lithium metal negative electrode and the safety performance of the battery, and has important practical application value.

Description

technical field [0001] The invention relates to the technical field of lithium secondary batteries, in particular to current collector technology for lithium secondary batteries, in particular to a composite 3D current collector and its preparation and application. Background technique [0002] With the rapid development of the economy, people consume more and more energy, and the non-renewable resources are decreasing day by day, which makes the field of batteries get more and more attention. Among the existing batteries, lithium-ion batteries are the most researched. Although the energy density of lithium-ion batteries is higher than that of lead-acid and nickel-metal hydride batteries, it still cannot meet people's needs for higher energy densities. Therefore, researchers will focus on research transferred to lithium metal secondary batteries. The high specific capacity (3860mAh / g) and low reduction potential (-3.04V vs SHE) of lithium metal make it the most promising an...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/66H01M10/052
CPCY02E60/10
Inventor 张华民陈雨晴张洪章李先锋贾子阳
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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