We demonstrate that peat moss, a wild plant that covers 3% of the earth's surface, serves as an ideal precursor to create sodium ion battery (NIB) anodes with some of the most attractive electrochemical properties ever reported for carbonaceous materials. By inheriting the unique cellular structure of peat moss leaves, the resultant materials are composed of three-dimensional macroporous interconnected networks of carbon nanosheets (as thin as 60 nm). The peat moss tissue is highly cross-linked, being rich in lignin and hemicellulose, suppressing the nucleation of equilibrium graphite even at 1100�C. Rather the carbons form highly ordered pseudo-graphitic arrays with substantially larger intergraphene spacing (0.388 nm) than graphite (c/2 = 0.3354 nm). XRD analysis demonstrates that this allows for significant Na intercalation to occur even below 0.2V vs. Na/Na+. By also incorporating a mild (300�C) air activation step, we introduce heirarchical micro and mesoporosity that tremendously improves the high rate performance through facile electrolyte access and further reduced Na ion diffusion distances. The optimized structures (carbonization at 1100�C + activation) result in a stable cycling capacity of 298 mAhg-1 (after 10 cycles, 50 mAg-1), with ~ 150 mAhg-1 of charge accumulating between 0.1V and 0.001V with negligible voltage hysteresis in that region, nearly 100% cycling coulombic efficiency, and superb cycling retention and high rate capacity (255 mAhg-1 at the 210th cycle, stable capacity of 203 mAhg-1 at 500 mAg-1).

Carbon nanosheet frameworks derived from peat moss as high capacity sodium ion battery anodes with superb cycling and rate capability

247th National Meeting (2014)

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