Lithium-sulfur battery

Abstract

The invention discloses a lithium-sulfur battery adopting a multi-layer composite separator. The multi-layer composite separator is characterized in that one side surface of a substrate separator is coated with a polymer layer A, the other side surface of the substrate separator is coated with an inorganic solid material layer and a polymer layer B, and the inorganic solid material layer is located between the substrate separator and the polymer layer B. The mechanical strength of the separator can be improved by the inorganic solid material layer, when a ceramic material with a lithium ion conduction function is used, the ionic conductivity of the separator can be improved effectively, and a polarization effect in charge-discharge processes is reduced. An electrolyte of the lithium-sulfurbattery contains an additive, therefore, interface state of a cathode, an anode and the separator is improved, charge-discharge current on the lithium anode surface is more uniform, activity of the lithium anode in the lithium anode can be reduced effectively, possibility of formation of lithium dendrites is reduced greatly, and use stability of the lithium anode is improved.

Description

technical field [0001] The invention belongs to the field of lithium-sulfur batteries, in particular to a multilayer composite separator for lithium-sulfur batteries. Background technique [0002] In today's society, while the rapid economic development enables people to obtain ample material life, the energy crisis and environmental pollution problems are increasingly perplexing the survival of human beings. In this severe situation, the development of new green energy and renewable energy, as well as the corresponding energy conversion and storage technologies are urgent problems to be solved by current scientific and technological workers. Due to the current problems, new energy vehicles and other electronic devices emerged as the times require. However, the lithium-ion batteries currently in circulation in the market have low energy density and cannot meet the high energy density requirements of new electrical equipment. It is imperative to develop a new power supply sy...

AI Technical Summary

Problems solved by technology

[0004] Although lithium-sulfur batteries have the incomparable advantages of high energy density compared to lithium-ion batteries currently on the market, their commercialization still faces many difficulties.

At present, the problems that limit the commercialization of lithium-sulfur batteries are mainly manifested in the following aspects: (1) The intermediate product Li produced during charging and discharging 2 S n (4≦n≦8), easily soluble in the electrolyte, while increasing the viscosity of the electrolyte, it diffuses through the separator to the metal lithium anode under the action of the concentration difference, and reacts with lithium to form a short-chain Li 2 S n (4≦n≦8) and Li 2 S 2 and Li 2 S, corrodes metallic lithium; and forms a "shuttle effect", reducing the Coulombic efficiency of the battery

(2) Product Li 2 S 2 , Li 2 S is insoluble in the electrolyte and deposited on the surface of the electrode, and the two are insulators, resulting in the loss of active materials and changes in the interface state between the electrode and the electrolyte, making the cycle performance of the battery worse.

(3) During the charge and discharge process, due to the uneven current density on the surface of the lithium negative electrode, lithium dendrites are formed, resulting in "death" and reducing the cycle life of the battery

In Chinese patent CN103151524A, sulfur is assembled into the pores of metal-organic framework (MOF) to prepare sulfur composite material, and then it is combined with carbon, which improves the cycle performance of lithium-sulfur batteries, but the loading capacity of S in MOF is relatively low. Small, the energy density of the battery is small

However, it is difficult to obtain a porous active layer with a good morphology gradient during the preparation process of the separator, and when used in a lithium secondary battery, the porous active layer is likely to cause interface instability when it is in direct contact with metal lithium.