Sulfur positive electrode of lithium sulfur battery and preparation method

Abstract

The invention provides a preparation method of a sulfur positive material of a lithium sulfur battery. The preparation method comprises the following steps: (a) washing lychee exocarp, drying the lychee exocarp, pulverizing the lychee exocarp into blocks, annealing the lychee exocarp blocks for 2+ / -0.5 hours at the temperature of 500+ / -50 DEG C under the protection of inert gases to obtain pyrolytic lychee exocarp; (b) activating the pyrolytic lychee exocarp obtained in the step (a) by utilizing KOH, and completely carbonizing the pyrolytic lychee exocarp to obtain biomass active carbon with a large specific surface area; (e) washing the carbonized powder after being cooled in step (d) by utilizing HCl solution and water until the pH value reaches 7; (f) placing the powder obtained in the step (e) into a blowing drying oven to be dried at the temperature of 80+ / -10 DEG C to obtain biomass active carbon powder; and (g) mixing the biomass active carbon powder obtained in the step (f) with sulfur powder according to a mass ratio of 0.3 to 1, and grinding the mixture to obtain black mixed powder. The prepared sulfur positive composite material for the lithium sulfur battery is high in specific capacity and long in cycle life, and 51 percent of initial capacity still can be maintained after the lithium sulfur battery is circulated for 800 times.

Description

technical field [0001] The invention relates to a positive electrode material for a secondary battery and a preparation method thereof, that is, a sulfur positive electrode of a lithium-sulfur battery and a preparation method thereof, in particular to a sulfur-based composite material containing biomass activated carbon and a preparation method thereof. Background technique [0002] In applications such as electric vehicles and smart grids, lithium-sulfur batteries have attracted widespread attention due to their very high energy density (theoretical up to 2600Wh / kg). However, the low electrical conductivity of elemental sulfur severely limits its practical applications. In addition, due to the long-chain lithium polysulfide (Li 2 S n , 4≤n≤8) will dissolve into the organic electrolyte, causing the shuttle effect. The shuttling of dissolved polysulfide ions between the sulfur cathode and the lithium anode not only leads to decreased Coulombic efficiency and loss of active...

AI Technical Summary

Problems solved by technology

However, the low electrical conductivity of elemental sulfur severely limits its practical applications.

In addition, due to the long-chain lithium polysulfide (Li 2 S n , 4≤n≤8) will dissolve into the organic electrolyte, causing the shuttle effect

Dissolved polysulfide ions shuttling between the sulfur cathode and the lithium anode not only lead to reduced Coulombic efficiency and loss of active species, but also hinder ion exchange on the electrode surface.

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