Lithium negative electrode with functional protective layer and lithium sulfur battery

Abstract

The invention relates to a lithium negative electrode with a functional protective layer and a lithium sulfur battery. The lithium negative electrode is provided with a functional protective layer which is coated on the surface and includes a conductive polymer. In the lithium sulfur battery, the functional protective layer of the lithium negative electrode is contacted with an electrolyte, so that a stable interface is formed between the electrolyte and a base body of the lithium negative electrode.

Description

Technical field [0001] The invention belongs to the field of electrochemical technology, and specifically relates to a lithium negative electrode with a functional protective layer and a lithium-sulfur battery including the lithium negative electrode. Background technique [0002] With the development of society, mobile phones, portable computers, electric cars, digital cameras, I-pads and other portable electronic products are flooding people's lives. Among them, as the main energy storage device, lithium batteries have occupied a dominant position in small devices. However, as people's requirements for portable life increase, traditional lithium batteries can no longer meet human needs. Therefore, the next generation of lithium batteries with high specific energy, high safety, long service life and low cost are high expectations. [0003] The positive electrode is the key to increase the specific energy of the battery. The sulfur cathode has a theoretical specific capacity of 1...

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Problems solved by technology

[0006] The above measures start from the inside of the battery electrode structure. Although it can reduce the impact of the shuttle effect on battery performance to a certain extent, the materials used are complicated to prepare and costly, which is not convenient for large-scale production.

At the same time, the problems in the negative electrode of lithium-sulfur batteries are serious and complex, and there are few related studies

[0007] The problems of the negative electrode of lithium-sulfur batteries mainly include the following three aspects: First, because the Fermi energy level of metal lithium is low, metal lithium is unstable to the electrolyte, and the SEI film formed between them is unstable. , and will be consumed during the cycle, which will cause loss of electrolyte and lithium anode, so in order to match the sulfur cathode, the lithium anode of the lithium-sulfur battery must be excessive, reducing the energy density of the battery

In addition, like other batteries using metal lithium as the negative electrode, during the long-term charging and discharging process of the battery, the uneven deposition of lithium causes the growth of lithium dendrites, and the continuous growth of lithium dendrites may puncture the separator, resulting in safety hazards. sexual problems

At the same time, for lithium-sulfur batteries, lithium polysulfides, the intermediate products of the electrochemical reaction of the battery, will dissolve in the electrolyte, they will migrate to the lithium negative electrode and react with them to form insoluble and insulating lithium sulfide, the generation of lithium sulfide will not only cause The loss of active material will cause the battery capacity to decay, and will increase the polarization of the battery. At the same time, the positive and negative reactions between lithium polysulfide and lithium sulfide will occur simultaneously during charging, reducing the Coulombic efficiency of the battery.

[0008] There is very little research work on lithium anodes for lithium-sulfur batteries, but for ordinary lithium anodes, the relevant work is summarized as follows: Part of the work revolves around electr

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