Honeycomb-like carbon materials derived from coffee extract via a “salty” thermal treatment for high-performance Li-I2 batteries

Abstract

Sustainable, conductive, and porous carbon materials are ideal for energy storage materials. In this study, honeycomb-like carbon materials (HCM) are synthesized via a “salty” thermal treatment of abundant and sustainable coffee extract. Systematic materials characterization indicates that the as-prepared HCM consists of heteroatoms (N and O, etc.) doped ultra-thin carbon framework, possesses remarkable specific surface area, and excellent electrical conductivity. Such properties bestow HCM outstanding materials to be the blocking layer for Li-I2 battery, significantly eliminating the dissolution of I2 in the cathode region and stopping the I2 from shutting to anode compartment. Furthermore, our electrochemical investigation suggests that HCM could incur surface pseudo-capacitive iodine-ions charge storage and contribute additional energy storage capacity. As a result, the resultant Li-I2 battery achieves a robust and highly reversible capacity of 224.5 mAh·g−1 at the rate of 10 C. Even under a high rate of 50 C, the remarkable capacity of the as-prepared Li-I2 battery can still be maintained at 120.2 mAh·g−1 after 4000 cycles.