Composite diaphragm for lithium metal secondary battery and preparation method and application of composite diaphragm

A composite separator and secondary battery technology, applied in the field of electrochemical power supply, can solve the problems of harsh operating environment, easy generation of lithium dendrites, piercing the separator, etc., to simplify the process, promote uniform deposition, and improve the effect of dendrite problems

Active Publication Date: 2020-11-24
INST OF CHEM CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] Therefore, the purpose of the present invention is to solve the problem that lithium dendrites are easily generated in the existing lithium metal negative electrode in the existing secondary battery, which can pierce the diaphragm and cause serious safety hazards, and provide a functional composite diaphragm that is simple and easy to operate, which can uniformly The deposition of lithium ions inhibits the generation of lithium dendrites, improves the cycle stability and safety of the battery, and avoids the tedious procedures and harsh operating environment of direct modification of lithium metal in the prior art

Method used

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  • Composite diaphragm for lithium metal secondary battery and preparation method and application of composite diaphragm
  • Composite diaphragm for lithium metal secondary battery and preparation method and application of composite diaphragm
  • Composite diaphragm for lithium metal secondary battery and preparation method and application of composite diaphragm

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Embodiment 1

[0045] This example is used to illustrate the preparation of the composite diaphragm of the present invention and its application in nickel-cobalt lithium manganate (NCM622) batteries

[0046] (1) Mix polyvinylidene fluoride (mass fraction 2wt.%), magnesium nitride particles (particle size is about 200nm, mass fraction 20wt.%) and N-methylpyrrolidone, and perform high-energy ball milling at a speed of 450rpm and ball milling time 4 Hour. After mixing, the solution was knife-coated on the surface of a commercial polyethylene separator with a spatula with a gap of 1 μm. Place the diaphragm at 50°C for drying treatment to obtain a composite diaphragm coated with magnesium nitride on the surface.

[0047] Figure 1(a) is a scanned image of the topography of the side coated with magnesium nitride, and Figure 1(b) is a scanned image of the cross-section of the composite diaphragm. It can be seen from Figure a that the magnesium nitride particles are evenly coated on the surface of ...

Embodiment 2

[0054] The composite diaphragm and battery were prepared in the same manner as in Example 1, except that the particle diameter of the coating active material used in step (1) was about 50 nm.

Embodiment 3

[0056] Composite separators and batteries were prepared in the same manner as in Example 1, except that the coating active material used in step (1) had a particle size of about 1 μm.

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Abstract

The invention provides a composite diaphragm for a lithium metal secondary battery and a preparation method and application of the composite diaphragm, the composite diaphragm comprises a diaphragm base layer and a functional coating coated on at least one surface of the diaphragm base layer, and the functional coating comprises active substance particles capable of reacting with lithium metal. The coating is transferred to the surface of a metal lithium negative electrode in the battery assembling process, an in-situ conversion reaction occurs in the subsequent battery circulation electrochemical process, a mixed electron ion conductor layer is generated, meanwhile, ion and electron distribution on an interface is adjusted, the ion concentration gradient is relieved, uniform lithium deposition is guided, and generation of lithium dendrites is inhibited. The lithium metal secondary battery applying the composite diaphragm shows excellent cycle performance and rate capability. The composite diaphragm provided by the invention avoids the tedious process and harsh operation environment of direct modification of lithium metal in the prior art, the preparation technology is simple, theraw materials are easy to obtain, and the composite diaphragm has extremely high practical and large-scale prospects.

Description

technical field [0001] The invention belongs to the field of electrochemical power sources, and in particular relates to a functional composite diaphragm for a lithium metal secondary battery and a preparation method thereof, a lithium metal secondary battery assembled using the diaphragm and its application in energy storage devices. Background technique [0002] Lithium-ion secondary batteries have been widely used in consumer electronics and communication fields. However, due to its limited theoretical capacity, its development and utilization are close to the limit. With the rapid development of hybrid electric vehicles and smart grids in the future, people have put forward higher and higher performance requirements for lithium-ion batteries in energy storage, such as high energy density and high safety. [0003] Lithium metal has attracted much attention due to its high theoretical specific capacity (3860mAh / g) and the lowest negative electrode electrochemical potentia...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M4/62H01M2/14H01M10/052H01M10/058H01M10/42
CPCH01M4/62H01M4/624H01M10/058H01M10/052H01M10/4235Y02E60/10Y02P70/50
Inventor 郭玉国严敏辛森殷雅侠万立骏
Owner INST OF CHEM CHINESE ACAD OF SCI
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