Lithium sulfur battery and preparation method thereof

Abstract

The invention provides a lithium sulfur battery and a preparation method thereof. The lithium sulfur battery comprises a 3D lithium metal negative electrode, a sulfide positive electrode and an electrolyte membrane, wherein the electrolyte membrane is arranged between the 3D lithium metal negative electrode and the sulfide positive electrode, wherein the 3D lithium metal negative electrode comprises a 3D framework material, a lithium-friendly layer, a metal lithium and a solid electrolyte, and the lithium-friendly layer covers the surface of the gap of the 3D framework material; the metal lithium is filled in the gap of the 3D framework material; and the solid electrolyte is filled in the gap of the 3D framework material. The lithium sulfur battery and the preparation method thereof can effectively inhibit the generation of lithium dendrites, reduce the problems of volume expansion and the like, and improve the safety of the lithium sulfur battery system.

Description

technical field [0001] The invention relates to the technical field of lithium-sulfur batteries, in particular to a lithium-sulfur battery and a preparation method thereof. Background technique [0002] With the rapid development of electric vehicles and mobile electronic devices, the current society's demand for high-energy-density lithium batteries has become increasingly prominent. The lithium-sulfur battery uses lithium metal as the negative electrode and polysulfide as the positive electrode, and its electrochemical reaction is as follows: 2Li+nS→Li 2 Sn(1≤n≤8)→Li 2 S, due to its high theoretical specific capacity and specific energy, which can reach 1672mAh / g and 2600Wh / kg respectively, and rich raw material resources, low price, and environmental friendliness, it is regarded as a very promising lithium battery technology. Among them, lithium metal, as an ideal anode material, has a higher theoretical specific capacity (3860mAh / g) and lower potential (-3.04vs. stand...

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Problems solved by technology

The use of lithium metal as the negative electrode material can effectively increase the energy density of the battery, expand the working voltage of the battery, and reduce the energy attenuation of the battery; however, there are great defects in the design of the traditional lithium-sulfur battery: (1) the use of lithium metal as the negative electrode , during the charging process, lithium ions will be deposited on the lithium metal to form dendrites, which can easily pierce the diaphragm, cause short circuit of the battery, and cause danger; (2) The electrolyte used in the traditional lithium-sulfur battery is a liquid electrolyte with a high specificity For high-energy lithium-sulfur batteries, the electrolyte is easy to decompose under high working current density, which affects the rate and cycle performance; and the phenomenon of polysulfides dissolving and shuttling in the electrolyte is serious, resulting in the loss of active materials and the destruction of the lithium metal negative electrode, reducing battery capacity and Kunlun efficiency; the generation of lithium dendrites will also increase the side reaction between the electrolyte and lithium metal, consume lithium active materials, and reduce the utilization rate, and the electrolyte is flammable and explosive, which makes the lithium-sulfur battery of this system very difficult. (3) The use of lithium metal as the negative electrode material also has serious electrode expansion problems during the cycle, which will produce infinite relative volume changes, reducing the cycle Coulombic efficiency and life of the battery

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