Molten Salt Method To Convert Waste PET Into Carbon Materials And Their Applications In Energy Storage Device

The pollution caused by the accumulation of spent plastic products,particularly liquid bottles,is a serious emerging threat to wildlife,habitats and ourselves.There are two main types of traditional recycling methods:physical methods and chemical methods.The quality of the products regenerated by the traditional method is low or the recycling cost is relatively high.Therefore,this study attempts to find a simpler,more environmentally friendly recycling method.In this study,an effective and scalable molten salt strategy for green conversion of PET plastic bottles into the porous carbon nanomaterial is proposed.The main contents are as follows:The effect of component of molten salt,comprising unitary KCl,MgCl2,ZnCl2,NaCl,KF and NaF on the structural and morphological evolution of PET upon heat treatment in air up to 1300℃ is investigated.It was observed that PET precursor was transformed into carbon materials with different morphological characteristics,including graphene-like nanosheets and porous nanostructures,with different electrical conductivity values,depending on the component of the salt employed.The melting and evaporation points as well as the cation size of the salt were found to have significant influences on the morphology and the crystallization level of the carbon products,based on which the characteristics of the carbon products were regulated.The possible mechanism involved in the conversion of PET into carbon nanostructures in molten salt is discussed.The results obtained provide insights into molten salt conversion of spent PET into value-added carbon materials for various applications.Furthermore,activation studies for Product-NaCl with outstanding conductivity were conducted.It was found that the specific surface area and pore diameter of the activated product were improved,while the outstanding conductivity was also maintained compared to the heattreaded product.Since the structure of the carbon product obtained in molten ZnCl2 is very suitable for applying in the electrode materials of supercapacitor,we have tested the performance of the supercapacitor of the three materials and obtained excellent capacitance performance.The supercapacitor assembled from carbon products obtained in molten ZnCl2 exhibits a large specific capacitance of 268.4 F g-1 at a current density of 0.2 A g-1.