Synthesis of Chl@Ti3C2 composites as an anode material for lithium storage

Abstract

Two-dimensional (2D) titanium carbide MXene Ti3C2 has attracted significant research interest in energy storage applications. In this study, we prepared Chl@Ti3C2 composites by simply mixing a chlorophyll derivative (e.g., zinc methyl 3-devinyl-3-hydroxymethyl-pyropheophorbide a (Chl)) and Ti3C2 in tetrahydrofuran, where the Chl molecules were aggregated among the multi-layered Ti3C2 MXene or on its surface, increasing the interlayer space of Ti3C2. The as-prepared Chl@Ti3C2 was employed as the anode material in the lithium-ion battery (LIB) with lithium metal as the cathode. The resulting LIB exhibited a higher reversible capacity and longer cycle performance than those of LIB based on pure Ti3C2, and its specific discharge capacity continuously increased along with the increasing number of cycles, which can be attributed to the gradual activation of Chl@Ti3C2 accompanied by the electrochemical reactions. The discharge capacity of 1 wt-% Chl@Ti3C2 was recorded to be 325 mA·h·g−1 at the current density of 50 mA·g−1 with a Coulombic efficiency of 56% and a reversible discharge capacity of 173 mA·h·g−1 at the current density of 500 mA·g−1 after 800 cycles. This work provides a novel strategy for improving the energy storage performance of 2D MXene materials by expanding the layer distance with organic dye aggregates.