Simple and Scalable Green Approach for Synthesizing Hierarchically Porous Hexagonal Shaped 3D Carbon Structure for Sodium-ion Storage

Both scientific and technological circles are gaining interest in the sustainable and scalable conversion of biomass waste into electrical energy storage systems. Three-dimensional hierarchical hexagonal porous carbon was synthesized from Ailanthus Triphysa sawdust for the first time. A two-step carbonization process results in etching of the carbon structure caused by ZnCl2 activation and tailoring pores over the carbon structure caused by gasification. The ZnCl2 acts as an activating agent, a template and a facilitator of the activation process, and its concentration regulates the porosity as well as specific surface area of the carbon nanostructures. There are two distinct types of pores in the prepared carbon i. e.mesopores and micropores. The highest specific surface area of 1757.80 m2/g was obtained when the ratio of ZnCl2 is four times higher than that of the sample. The resulting carbon is used as an electrode in an electrochemical supercapacitor which gives a specific capacitance of 92.24 F/g at 5 mV/s and a cyclic stability of 3000 with a retention of 98 %. The highly porous activated carbon exhibits excellent electrochemical storage properties in an aqueous neutral electrolyte of 0.1 M Na2SO4. A redox-enhanced electrolyte like 0.1 M Na2SO4 with 0.03 M KI combination improvise the specific capacitance and cyclic stability. The specific capacitance of the redox-enhanced electrolyte combination increases to 104 F/g at 5 mV/s and cyclic stability of 50000 with a retention of 95 % during continuous charge-discharge cycles. This work brings forth a simple and green approach to transforming biomass waste into a scalable and economic high-performance supercapacitor. Three-dimensional hierarchical hexagonal porous carbon synthesized from Ailanthus Triphysa sawdust via a two-step carbonization process results in etching of the carbon structure caused by ZnCl2 activation and tailoring pores over the carbon structure caused by gasification.image