A kind of separator comprising graphene/cellulose composite material and preparation method thereof

Abstract

The invention discloses a diaphragm containing a graphene / cellulose composite material, and a preparation method thereof. The diaphragm comprises a diaphragm base layer, a graphene / cellulose compositematerial layer on the surface, facing a positive electrode, of the diaphragm base layer, and another graphene / cellulose composite material layer on the surface, facing a negative electrode, of the diaphragm base layer, wherein the graphene / cellulose composite material layers comprise graphene, cellulose and other auxiliary agents. In use, the diaphragm containing the graphene / cellulose compositematerial has the characteristics of low thickness, high imbibition rate and low resistance, and enables a lithium ion battery to have high capacity and long service life; and the graphene component ofthe diaphragm can effectively form a heat transmission network and diffuse heat in time when the phenomenon of local overheating occurs, so the heat resistance of the diaphragm is improved, and the safety performance of the battery is improved. The preparation method for the diaphragm is simple in process, mild in reaction conditions, short in production cycle, and capable of realizing large-scale industrial production.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a diaphragm containing graphene / cellulose composite material and a preparation method thereof. Background technique [0002] Lithium-ion batteries generally use materials containing lithium elements as electrodes, which are representatives of modern high-performance batteries. It is favored by researchers for its small size, light weight, high working voltage, high specific energy, long cycle life, and no pollution. It can be widely used in various fields of aerospace, electronic devices and daily life. Lithium-ion batteries currently in use are generally composed of positive and negative electrodes, electrolytes and separators. The separator is one of the key inner components of the lithium-ion battery, which mainly relies on the movement of lithium ions between the positive and negative electrodes to work. During the charging and discharging process...

AI Technical Summary

Problems solved by technology

[0003] At present, the separators commonly used in lithium-ion batteries are multi-layer structures or ceramic-coated separators; they can play a good role in blocking positive and negative materials and supports, and when the separator is punctured, local heating will occur. If the diaphragm barrier layer can quickly melt and close the cells, it can prevent the battery from exploding due to heat, but when the local heating rate is greater than the melting rate, the blocking effect cannot be achieved.

Moreover, after long-term use, metal lithium will crystallize on the negative electrode to form dendritic metal lithium—dendrites; when the dendrites grow to a certain extent, they will puncture the diaphragm, causing an internal short circuit in the battery, which seriously threatens personal safety. This severely limits the extension of the service life, energy density and theoretical capacity of Li-ion batteries

[0004] Not only that, the energy density and actual capacity of lithium-ion batteries prepared by the current technology are relatively low, which can no longer meet people's needs; the main reason is that the performance of the separator directly affects the internal resistance of the battery, discharge capacity, The cycle life and the safety performance of the battery, therefore, the manufacture of lithium-ion batteries has extremely high requirements for the consistency of the separator material products. In addition to the basic requirements of thickness, surface density, and mechanical properties, the size and distribution of the separator micropores Uniformity also has high requirements

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