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Yat Li1

1, University of California, Santa Cruz, Santa Cruz, California, United States

Supercapacitors are rapidly emerging as a new class of charge storage devices that can be used in a broad range of applications. Supercapacitors distinguish from lithium ion batteries by their ability to be charged and discharged at ultrafast rates. Unfortunately, previous studies have primarily focused on improving the charge/discharge performance of supercapacitor materials at relatively low current densities. This is one of the main obstacles to more widespread adoption of supercapacitors for ultrafast charging devices. Carbons are the most widely researched candidates for supercapacitors. The rational creation of unique multi-scale pore network in carbon structure not only significantly increases the electrode surface area, but also facilitates ion diffusion and charge transfer. In this talk, I will present some recent development in a novel carbon architecture with multi-scale pores that achieves record high specific capacitance at ultra-high current density. The carbon electrode yields a remarkable gravimetric capacitance of 374.7±7.7 F g-1 at a current density of 1 A g-1, and more importantly, it retains 235.9±7.5 F g-1 at an ultrahigh current density of 500 A g-1. The electrode retains 60% of its capacitance when current density is increased by 500 times from 1 A g-1 to 500 A g-1. This performance greatly exceeds the performance of other conventional carbon electrodes. Key breakthroughs that made this performance possible include: 1) the carbon electrode with multi-scale pores exhibits an extremely large surface area of 2905 m2 g-1; 2) the unique combination of multi-scale pores allows efficient ion diffusion and charge transfer, supporting much faster charge/discharge rates without significantly degrading capacitance. The findings pave a way for improving rate capability of supercapacitors and their capacitances at ultrahigh current densities, which is a long standing challenge for ultrafast charging devices.

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