Carbon nanosheets prepared with a vermiculite template for high-performance lithium-ion batteries via space-confined carbonization strategy

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Carbon nanosheets (CNSs) having both graphite microcrystalline layers and amorphous carbon structures are prepared by a space-confined carbonization strategy using glucose, sucrose and starch as carbon sources which are inserted into the confined space of vermiculite templates by liquid-phase impregnation intercalation. The microstructures of CNSs are strongly depended on the molecular weight of carbon precursors. In the Starch-CNSs synthesized from starch with larger molecular weight, single nanosheets contain more ordered graphite microcrystalline layers and fewer microporous defects as well as richer oxygen-containing functional groups, and the disordered stacking of single nanosheets form more mesoporous structures. The specific surface area and nanosheets thickness of Starch-CNSs are 400 m2·g−1 and 3.934 nm. Starch-CNSs as anode for lithium-ion batteries exhibit excellent lithium storage properties, combining initial Coulombic efficiency (56 %), high specific capacity (637mAh/g at 0.05 A/g), excellent rate performance (253 mAh/g at 2 A/g) and cycling stability (262 mAh/g at 2 A/g after 500 cycles). These results show the CNSs derived from larger molecular weights outperform these from lower counterparts, providing strong evidence and reference for selecting suitable molecular weight carbon precursors to prepare high-performance CNSs anode for lithium ion batteries.