Partially Graphitized and Dense Porous Carbon for Edlc Electrodes with High Volumetric Performance

Abstract

With high-end applications of electric double layer capacitors (EDLCs) in fields of vehicle and aerospace, it is a great challenge to construct lightweight and compact EDLCs. Herein, using polyvinyl pyrrolidone (PVP) as soft template and sulfonated pitch (SP) as carbon source, the dense porous carbons (DPCs) with high pore connectivity and high packing density were prepared by intermolecular hydrogen bonding, capillary densification and KOH activation strategies. The PVP plays a crucial role in structure formation of DPCs. Firstly, PVP molecules can induce the structural orientation of SP molecules and then promote the formation of carbon microcrystals and dense structure of DPCs. Secondly, the decomposition of PVP molecules can form numerous connected pores, which greatly increase the connectivity and effective utilization of pores. The optimized 0.3DPC sample simultaneously owns large pore volume (1.06 cm3 g-1) and high density (0.641 g cm-3). Also it contains a few surface O atoms (8.3 at.%). Thus, this sample achieves high Cv of 82 F cm-3 at 0.05 A g-1, and good rate capability of 79% in TEABF4/PC electrolyte. The cyclic stability of 0.3DPC is up to 94.6% over 10,000 cycles. Likewise, it acquires high Ev of 39.1 Wh L-1 at 3.5 V in EMIMBF4 electrolyte.

Keywords: Polyvinyl pyrrolidone, Self-assembly, Dense porous carbon, Electric double layer capacitor, High volumetric performance