High-Performance Asymmetric Li-Ion Pseudocapacitors Based on Pyroprotein Nanowebs

초록

Modern industrial technologies require high power and energy storage devices with long-term cycling stabilities; the electro-chemical performances of these devices are mainly dependent on the active electrode materials and their energy storage mechanisms. In this study, nanoweb-structured pyroprotein nanofibers (NW-PNFs) were prepared from electrospun silk protein by pyrolysis. NW-PNFs have an open macroporous structure formed by entangled nanofibers and numerous micropores originating from the amorphous pseudographitic microstructure of the nanofibers. In addition, they possessed a large number of heteroatoms (10.3 at.% oxygen and 5.2 at.% nitrogen). These material properties led to superior Li-ion storage performances with high reversible capacity of about 1,050 mAhg(-1) at 0.5 Ag-1 and great cycling performance over 3,000 cycles. In particular, NW-PNFs exhibited high rate capability even at the specific current of 50 Ag-1, at which the high specific capacity of circa 400 mAhg(-1) was achieved. Furthermore, asymmetric Li-ion storage devices based on NW-PNFs showed feasible electrochemical performances with a maximum specific energy of 235.7 Whkg(-1) at 188.6 Wkg(-1) and maximum power of 21,220 Wkg(-1) at 69.6 Whkg(-1).

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