Macroporous Catalytic Carbon Nanotemplates for Sodium Metal Anodes

초록

Because of its remarkably high theoretical capacity and favorable redox voltage (-2.71 V vs the standard hydrogen electrode), Na is a promising anode material for Na ion batteries. In this study, macroporous catalytic carbon nanotemplates (MC-CNTs) based on nanoweb-structured carbon nanofibers with various carbon microstructures are prepared from microbe-derived cellulose via simple heating at 800 or 2400 degrees C. MC-CNTs prepared at 800 degrees C have amorphous carbon structures with numerous topological defects, and exhibit a lower voltage overpotential of approximate to 8 mV in galvanostatic charge/discharge testing. In addition, MC-CNT-800s exhibit high Coulombic efficiencies of 99.4-99.9% during consecutive cycling at current densities ranging from 0.2 to 4 mA cm(-2). However, the carbon structures of MC-CNTs prepared at 800 degrees C are gradually damaged by cycling. This results in significant capacity losses after about 200 cycles. In contrast, MC-CNTs prepared at 2400 degrees C exhibit well-developed graphitic structures, and maintain predominantly stable cycling behaviors over 1000 cycles with Coulombic efficiencies of approximate to 99.9%. This study demonstrates the superiority of catalytic carbon nanotemplates with well-defined pore structures and graphitic microstructures for use in Na metal anodes.

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