Preparation Of Graphene/Carbon Black Hybrid Materials And Its Application For Energy Storage

Due to the energy and environmental issues, development and utilization ofnew energy is vital important for sustainable development. Therefore, manyrequirements for energy transfer and storage are proposed correspondly.Supercapacitor (SC) and lithium ion battery (LIB) are two kinds of well-studiedand widely used promising energy storage devices. In order to further enhancetheir electrochemical performance, fast ions and electrons conducting channelsshould be constructed. Graphene (GN) is the most flexible and thinnesttwo-dimensional carbon materials. Due to its unique structure and excellentelectrical and thermal conductivity, GN has been widely investigated in the fieldof new energy. Graphene oxide (GO) prepared by the chemical method ischaracterized by its rich surface functional groups, and many kinds of GNhybrid materials can be obtained through GO. A kind of reduced grapheneoxide/carbon black (RGO/CB) hybrid material is successfully fabricated. Stringof CB can be fabricated at the surface of RGO, which will further enhance itselectronic conductivity and keep the RGN nanosheets from stacking to constructconducting network for ions. At the same time, the porous structure of CB canalso increase the electrolyte at the surface of active material, and hence enhancefurther the rate performance of SC and LIB.Firstly, with the help of the negatively charged GO and positivly chargedcationic surfactant cetyltrimethyl ammonium bromide dispersion of carbonblack, the GO/CB dispersion can be obtained. Under the hydrothermal process,RGO/CB hybrid material will be fabricated self-assembly. After thehydrothermal process, most of the hydroxyfrom the GO is depleted, but manyother oxygen-containing functional groups are still present. The carbon blackstring can be uniformly dispersed as the skeleton on the surface of GN sheetsand forms a stable three-dimensional porous structure, which provide athree-dimensional conductive network for electrons and ions.On one hand, the as-obtained RGO/CB is successfully applied for SC. The specific capacitance reach to154F/g when the current density is40A/g, whichshows an excellent rate performance with capacitance retention of65%. Afterbeing heated at300℃, the specific capacitance increase to172F/g and the rateperformance improves and with a very high retention of98%after cycling for20000cycles. On the other hand, after being thermal treated under Aratmoshpere at900℃, the RGN/CB hybrid materials (denoted as GN/CB-900)becomes an effective conducting additive for LiFePO4in LIB. With the only5wt%addition fraction of GN/CB-900, the LiFePO4LIB shows much betterelectrochemical performance than that with10wt%of carbon black. Thespecific capacity can reach to72mAh/g even at the charge/discharge rate of10C. What’s more, the GN/CB-900electrode shows excellent cycle stability. After100cycles at1C, it still maintain98%of the initial capacity.