Tailored Electrosynthesis of Highly Porous Ti₃SiC₂-Derived Carbon Anodes with Excellent Lithium Storage Properties

Two-dimensional (2D) porous carbon materials have received tremendous attention as functional materials for energy storage applications. However, the preparation of 2D porous carbon through conventional etching methods is energy-intensive and causes environmental concerns. Besides, preparing highly porous 2D carbide-derived carbon materials with hierarchical pore structures still remains challenging. Herein, we report the sustainable synthesis of 2D carbide-derived carbon by molten salt electrochemical etching (MSE) of ternary carbide (MAX) precursors. The etching mechanism from Ti₃SiC₂ to Ti₃SiC₂-derived carbon (Ti₃SiC₂-CDC) was systematically investigated. The results show that the Cl^- in the molten salt would adsorb on the active sites of the Ti and Si atoms and oxidize sequentially to form SiCl₄ and TiCl₄ stripped from the Ti₃SiC₂ precursor during electrochemical etching, resulting in Ti₃SiC₂-CDC. The as-prepared porous Ti₃SiC₂-CDC with hierarchical pores was evaluated as an anode for Li-ion batteries, which shows a favorable reversible capacity of 712.9 mAh g^-1 after 300 cycles at 100 mAh g^-1 as well as a highly reversible capacity of 375.6 mA h g^-1 even at a current density of 500 mAh g^-1. Given the unique etching mechanism and the scalability of the method, this work sheds light on the cleaner and more sustainable design and synthesis of other 2D carbon-based materials with tunable pores for advanced energy storage devices.