Lithium metal negative electrode with double-layer interface film, preparation thereof and application

Abstract

The invention relates to a lithium metal negative electrode with a double-layer interface film, preparation of the lithium metal negative electrode, and application. The double-layer interface film isattached to the surface of lithium metal; the inner layer of the double-layer interface film is a lithium fluoride inorganic layer; the outer layer of the double-layer interface film is an ether polymer layer. When the interface film is applied to a lithium metal battery, the inner-layer compact film of the interface film can inhibit dendrite growth on the surface of lithium metal, the outer-layer flexible film of the interface film can effectively relieve the breakage of the lithium fluoride layer caused by the volume expansion of a negative electrode, and therefore, interface stability is improved, continuous reaction and consumption of the lithium negative electrode and an electrolyte are inhibited, and the cycle life of the battery is prolonged. In addition, due to the introduction oforganic lithium salt into the interface film, interface lithium ion transmission is greatly accelerated, and lithium deposition uniformity is improved.

Description

technical field [0001] The invention relates to a metal lithium negative electrode inorganic / polymer mixed double-layer interface film Background technique [0002] Currently, the world market for electric vehicles and portable electronic devices including passenger cars, buses and passenger cars is growing rapidly. Lithium-ion batteries with high charge-discharge voltage and long cycle life are widely used as power sources for portable electronic devices and electric vehicles, but due to the limitation of their theoretical energy density, it is necessary to develop new electrode materials with higher energy density. Among them, lithium metal has a high theoretical energy density (3860mAh g -1 ) and low electrochemical potential (-3.040V vs. SHE) have attracted great attention from researchers in recent years. [0003] However, there are still two problems to be solved urgently in the application of lithium metal anode. One is the lithium dendrite problem. Due to the inh...

AI Technical Summary

Problems solved by technology

Lithium metal will spontaneously react with the electrolyte to form a solid electrolyte interfacial film (SEI), which is continuously damaged and repaired as the volume of the negative electrode expands during the charge-discharge cycle, resulting in continuous consumption of lithium metal and electrolyte, reducing the Coulombic efficiency of lithium metal batteries and cycle life

[0004] At present, relevant solutions have been proposed, and the growth of dendrites can be suppressed by designing a 3D framework structure and using a solid electrolyte, but there are still some problems to be solved urgently.

The 3D skeleton structure can slow down the growth of dendrites by reducing the current density, but it cannot isolate the direct contact between lithium metal and the electrolyte to inhibit the occurrence of side reactions; while the inorganic solid-state electrolysis has high mechanical strength, but the interface resistance is large, and the contact with lithium metal is poor. ; Although the polymer electrolyte has good flexibility and elasticity, the ionic conductivity at room temperature is relatively low (-4 S cm -1 )

However, the lithium fluoride ion conductivity of this layer is low and it is easy to break with the volume expansion of the negative electrode, so it is necessary to further improve the ion transport ability and flexibility of the interface layer.

Constructing a layer of organic polymer on the surface of lithium can adapt to the volume change caused by the process of lithium deposition and dissolution, but the mechanical strength is low, and the ionic conductivity of the crystalline polymer bulk phase at room temperature is low.

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