A kind of lithium-sulfur battery positive electrode and its manufacturing method

Abstract

A lithium sulfide battery cathode and a manufacturing method therefor are disclosed. A gel electrolyte layer composed of a polymer matrix, a conductive filler and an electrolyte is coated on the surface of a cathode sulfide-containing active material layer, so that the gel electrolyte layer has both ionic conductivity and electronic conductivity. The lithium-sulfur battery cathode fully combines the advantages of a coating positive electrode and a gel electrolyte, and at the same time, the defects of the coating positive electrode and the gel electrolyte are abandoned as far as possible, thereby contributing to the establishment of a stable and efficient lithium-sulfur battery system, and comprehensively improving the performance of the battery, such as capacity, cycle, multiplying power and the like.

Description

technical field [0001] The invention belongs to the technical field of new energy, and in particular relates to a positive electrode of a lithium-sulfur battery and a manufacturing method thereof. Background technique [0002] Lithium-sulfur batteries have the advantages of high energy density, environmental friendliness, and abundant sources of raw materials. They have become one of the energy storage devices with great development potential, and have attracted extensive research and attention from researchers all over the world. However, at this stage, the battery still has defects such as low utilization rate of active materials, short cycle life, poor rate performance, and serious self-discharge, which has seriously hindered its development since its introduction in the 1960s. The main reasons are as follows: : [0003] 1) Elemental sulfur and its reduction products are electron and ion insulators at room temperature, which affect the conversion and utilization of mater...

AI Technical Summary

Problems solved by technology

However, at this stage, the battery still has defects such as low utilization rate of active materials, short cycle life, poor rate performance, and serious self-discharge, which has seriously hindered its development since its introduction in the 1960s. The main reasons are as follows: :

[0003] 1) Elemental sulfur and its reduction products are electron and ion insulators at room temperature, which affect the conversion and utilization of materials;

[0004] 2) The volume continuously expands / shrinks during sulfur lithiation / delithiation, causing instability or even failure of the electrode structure;

[0005] 3) A series of intermediate polysulfides formed during charging and discharging are easily dissolved in the electrolyte and diffuse to the negative electrode to form a shuttle effect, causing a series of problems such as loss of active materials, corrosion of metal lithium, internal self-discharge, and deposition of insulating products

[0006] To this end, the researchers compounded elemental sulfur with various porous carbons with high specific surface area and high conductivity to enhance the conductivity of the positive electrode. At the same time, the porous carbon was used to confine the active material. Dissolution is still inevitable

There is also a coating structure on the surface of the positive electrode to physically block polysulfides by using the coating. However, if the coating is too dense or too thick, it will hinder the penetration of the electrolyte, increase the ion transmission impedance, and affect the electrode reaction.

Moreover, the coating cannot fully adapt to the volume deformation of the electrode, and may fall off during battery cycling.

In addition, since the dissolution and shuttling of polysulfides both occur in the electrolyte, polysulfides can also be better restricted by using gel electrolytes, but most gel electrolytes only have ion conductivity and no electronic conductivity, and It belongs to a two-phase system with the positive electrode, and there are hidden dangers in the contact resistance and interfacial compatibility of the electrolyte / positive electrode

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