Hollow spherical ceo for lithium-sulfur battery cathode 2-x Preparation method of @c composite material

Abstract

The invention relates to a hollow spherical CeO used for the positive electrode of a lithium-sulfur battery 2‑x Preparation method of @C composite material with SiO 2 spheres as templates on SiO by a hydrothermal method 2 CeO 2 , the SiO 2 After the spheres are etched away with NaOH, the hollow CeO 2 Nanospheres, the product is coated with polydopamine by high-speed stirring, and CeO can be obtained after calcination 2‑x @C Composite.

Description

technical field [0001] The invention belongs to the technical field of electrode materials for lithium-sulfur batteries, and in particular relates to a hollow spherical CeO containing oxygen vacancies which can effectively absorb lithium polysulfide, inhibit its dissolution and diffusion, and catalyze and accelerate reaction kinetics for the positive electrode of lithium-sulfur batteries. 2-x A method for preparing a sulfur positive electrode coated with a carbon shell. Background technique [0002] Nowadays, with the rapid development of electronic devices and electric vehicles, the market has a higher demand for high energy density rechargeable batteries. In lithium-sulfur batteries, sulfur is used as the positive electrode, which has high theoretical specific capacity (1675mAh / g) and high theoretical specific energy (2600Wh / kg). Because of its low power consumption, it has attracted extensive attention from researchers and is considered to be the next generation of secon...

AI Technical Summary

Problems solved by technology

However, the sulfur cathode also has the following problems: 1) sulfur is reduced to lithium sulfide (Li 2 During the discharge process of S), a multi-step reduction reaction occurs, undergoing a solid-liquid-solid transformation, and a variety of intermediate products lithium polysulfide (Li 2 S x , 4≤x≤8) and then reduced to Li 2 S 2 and Li 2 S, in which the long-chain polysulfide lithium is easily dissolved in the ether electrolyte, resulting in the loss of active materials, resulting in capacity attenuation and poor cycle stability of the battery

2) Between the positive and negative electrodes, the long-chain lithium polysulfide will form a concentration difference in the electrolyte, and under the action of the concentration gradient, a shuttle effect will occur between the positive and negative electrodes, resulting in low Coulombic efficiency

3) Sulfur and Li 2 The poor conductivity of S reduces the utilization rate of active materials, and the volume expansion of 80% after lithiation will also cause battery safety problems. The above factors make it far from commercial applications.

Among them, carbon materials with high conductivity and large specific surface area, such as graphene, carbon nanotubes, porous carbon, hollow carbon spheres and their composite materials, mainly bind lithium polysulfide through physical adsorption, and at the same time make up for sulfur The disadvantage of poor conductivity, but the weak van der Waals binding force between non-polar carbon and polar lithium polysulfide cannot effectively inhibit the dissolution and diffusion of lithium polysulfide

Images