Preparation of Graphite from Fish Scales

Graphite with relatively high specific capacity (372mAh g^-1), cycling efficiency and low irreversible charge is nowadays the choice of the lithium-ion batteries [1,2]. In order to improve the electrochemical performance of graphite, many reports focused on the selection of suitable carbon precursors with easy graphitization [3,4]. In this work, fish scale with a layer-by-layer structure inspired us to prepare graphite from it. The advantages are as follows: 1) it is as an abundant food waste; 2) collagen as its main composition has high carbon content (about 50%); 3) the preparation process could be easy. The fish scales have been carbonized at 900℃ with a heating rate of 3℃ min^-1 under a flowing N_2. The obtained carbon was diluted by acid and then graphited at 2800℃. The BET surface area of the as-prepared fish-scale-based graphite is 5 m² g^-1 and the Raman I_D/I_G ratio only remains 0.04 (Fig. 1a) which illustrates a low degree of defects and a high degree of crystallinity. The initial discharge specific capacity is 310 mAh g^-1 and keeps 300 mAh g^-1 with the coulombic efficiency 99.6% after 150 cycles (Fig. 1b). These results state that the fish-scale-based graphite is a promising material for the anode of lithium-ion batteries. 

Fig. 1 (a) Raman spectra (514 nm laser) and (b) Cycle performance and corresponding Coulombic efficiency at a current density of 50 mA g^-1 for the fish-scale-based graphite.

Acknowledgments

Financial support from the National Natural Science Foundation of China (no.51272017 and 51432003) is gratefully appreciated. 

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