Three-Dimensional Porous Carbon Materials with High Surface Area for Electrochemical Energy Storage

Abstract

Supercapacitors are widely recognized as an important class of energy storage devices because they can provide a high specific power and long cycle life. Electrical double-layer capacitors (EDLCs) store charge and release electric energy through the transfer of ions to and from the electrode/electrolyte interface without a Faradaic reaction. Therefore, the amount of energy stored by EDLCs is dependent on the surface area of the electrodes available for electrolyte ion access. However, for the use of the commercial carbon materials such as activated carbon and CNT etc., a poor energy density is observed due to the lack of porous structure which limits the active area for charge storage. Thus, great efforts have been focused on preparation of 3D-porous structure carbons for EDLCs to improve upon these factors. In this work, a new type of advanced 3D macroporous carbon material derived from PIM-1 with a high surface area and electrical conductivity is proposed and anticipated for energy storage applications. PIM-1 (polymer of intrinsic microporosity) is a polymer with a large fractional free-volume with a high surface area of 760 m2/g and chosen as precursor material for carbonization. 3D macroporous PIM-1 films (NPIMs) with continuously interconnected structure were fabricated by applying the nonsolvent-induced phase inversion method. Finally the carbonized NPIMs (cNPIMs) were obtained through direct high temperature pyrolysis of NPIMs without any external activation agent. The cNPIMs presented a very large surface area (2101.1 m2/g) with narrow micropore size distribution (0.75 nm) as shown in Fig. 1. The SEM analysis revealed that cNPIMs also have a unique 3D macroporous structure having both dense skin layer and gradient pore structure, which is expected to grant a smooth and easy ion transfer capability as an electrode material. Consequently, the cNPIM exhibits a high capacitance (405.8 F/g) and long-term stability in aqueous electrolyte. We believe that our approach can provide a variety of new 3D macroporous carbon materials for the application in a electrochemical energy storage. Figure 1