Preparation of graphitic carbon nanosheets by reaction between CO2 and CaC2 for lithium-ion batteries

Abstract

A simple route to prepare graphitic carbon nanosheets (GCNSs) through thermal reaction between CO2 and calcium carbide (CaC2) is reported. The yield is about 85% at 700 °C according to the amount of CaC2 fed. The reaction encounters great kinetic difficulty at lower temperatures, while at higher temperatures, the yield would decrease due to the reaction between GCNSs and CO2. Spectroscopic analysis and morphologic observations demonstrate that the GCNSs have a thickness of about 10–50 nm and a lateral size of 1–10 μm. The as-prepared GCNSs delivered an initial reversible capacity of 513 mAh g−1 at a current density of 100 mA g−1 and a capacity of 494 mAh g−1 after 200 charge-discharge cycles in a potential range between 0.01 and 3.0 V vs. Li/Li+. It also showed a good rate performance with a reversible capacity of 293 mAh g−1 at 1000 mA g−1. These high performances can be linked to the special cambered crumpled structure of the GCNSs with some lattice defects, which ensure fast solid diffusion in addition to providing effective liquid channels in the electrode. Our findings promises an efficient route to convert the environmental carbon sources, including CO2, to high value GCNSs.