Purifying process for graphene material of energy storing device

Abstract

The invention discloses a purifying process for a graphene material of an energy storing device, and further relates to a purifying and washing process for a graphene material of energy storing devices such as a super capacitor, a secondary lithium ion battery and the like. The purifying process disclosed by the invention comprises the following steps of: washing graphene obtained by activating with a strong alkali with deionized water of over 30 DEG C; repeatedly purifying and cleaning with a cleaning solution of over 30 DEG C; repeatedly washing with deionized water of over 30 DEG C; and calcining the graphene at the high temperature of 500-1,200 DEG C for 0.5-10 hours to obtain high-purity graphene powder. The process flow is simple and ordered, every joint in the flow can be controlled accurately, the content of heavy metal ions can be lowered to be below 300 ppm after purification, and the content of the alkali metal ions can be lowered to be below 1,500 ppm; and the purifying process is particularly suitable for large-scale production.

Description

technical field [0001] The invention discloses an impurity removal process, and furthermore, relates to an impurity removal process for graphene materials of energy storage devices. Background technique [0002] Graphene is suitable as an active material for energy storage due to its extremely high specific surface area for secondary lithium-ion batteries and supercapacitors. However, in the process of using alkali metal hydroxides to activate and manufacture graphene, because hydroxides are highly corrosive at high temperatures, they can corrode the activation furnace body, and a large amount of heavy metals are mixed into the activated graphene materials. (such as Al, Ni, Cr, Zn and Cu, etc.) and alkali metal (Na and K) impurities. These metal compounds formed at high temperature have complex structures and stable properties. It is difficult to completely remove the above-mentioned metal compound impurities by simple water washing. Generally, after treatment by the existi...

AI Technical Summary

Problems solved by technology

However, in the process of using alkali metal hydroxides to activate and manufacture graphene, because hydroxides are highly corrosive at high temperatures, they can corrode the activation furnace body, and a large amount of heavy metals are mixed into the activated graphene materials. (such as Al, Ni, Cr, Zn and Cu, etc.) and alkali metal (Na and K) impurities. These metal compounds formed at high temperature have complex structures and stable properties. It is difficult to completely remove the above-mentioned metal compound impurities by simple water washing. Generally, after the existing impurity removal technology, the content of heavy metal ions is greater than 1000 ppm, and the content of alkali metal ions is greater than 3000 ppm

After the graphene material containing metal ion impurities is used as the electrode substrate of the energy storage device, the alkali metal ions and heavy metal ions will be reduced and precipitated during the charging and discharging process, and dendrite metal particles will be formed on the pole piece, resulting in isolation. Problems such as board perforation, causing device short circuit and other faults

At the same time, these metal ions will cause the energy storage device to self-discharge and reduce the self-discharge retention rate.

What's more serious is that these reduced metal particles will react with the electrolyte to generate gas during the charging and discharging process, causing the electrode to expand and collapse, thereby shortening the service life of the energy storage device.