Metal Chloride‐Induced Hydrogen Transfer Enables Efficient Conversion of Aromatic Hydrocarbons for Sodium Storage

Abstract The cost‐effective synthesis of high‐performance hard carbons (HCs) is a key step of sodium‐ion batteries toward practical applications. Considering the rich resource of low‐value aromatic hydrocarbons (e.g., pitch), there is tremendous interesting in its conversion into value‐added HCs. Unfortunately, it still lacks an efficient way for the synthesis, in addition to the time‐consuming oxygen contamination of the carbon framework. Herein, a universal strategy is reported that enables the efficient synthesis of HCs from pitch by modulating hydrogen transfer using metal chlorides. CuCl₂ is selected as the model modulator and the effect of different metal chlorides (FeCl₃, AlCl₃, ZnCl₂, and MgCl₂) are further explored. Based on material characterizations and density functional theory calculation employing 1‐methylnaphthalene as the model molecule, it shows that the hydrogen capture and chlorination reactions mediated by CuCl₂ and FeCl₃ are thermodynamically favored, which promote the crosslinking of pitch to form HCs. After optimization, the derived HC exhibits superior performance of reversible capacity of 304.8 mAh g⁻¹ and a high initial Columbic efficiency of 88.4%. These discoveries provide new insights into the synthesis of HCs from aromatic hydrocarbons, facilitating their utilization in electrochemical energy storage.