Microcrystalline Hybridization Enhanced Coal‐Based Carbon Anode for Advanced Sodium‐Ion Batteries

Abstract

Sodium‐ion batteries (SIBs) are regarded as a kind of promising candidate for large‐scale energy storage technology. The development of advanced carbon anodes with high Na‐storage capacity and initial Coulombic efficiency (ICE) from low cost, resources abundant precursors is critical for SIBs. Here, a carbon microcrystalline hybridization route to synthesize hard carbons with extensive pseudo‐graphitic regions from lignite coal with the assistance of sucrose is proposed. Employing the cross‐linked interaction between sucrose and lignite coal to generate carbon‐based hybrid microcrystalline states, the obtained hard carbons possess pseudo‐graphitic dominant phases with large interlayer spaces that facilitate Na ion's storage and transportation, as well as fewer surface defects that guarantee high ICE. The LCS‐73 with an optimum cross‐link demonstrates the highest Na‐storage capacity of 356 mAh g ⁻¹ and an ICE of 82.9%. The corresponding full‐cell delivers a high energy density of 240 Wh kg ⁻¹ (based on the mass of anode and cathode materials) and excellent rate capability of 106 mAh g ⁻¹ at 10 C in addition to outstanding cycle performance with 80% retention over 500 cycles at 2 C. The proposed work offers an efficient route to develop high‐performance, low‐cost carbon‐based anode materials with potential application for advanced SIBs.

Abstract

A novel carbon microcrystalline hybridization route is proposed to synthesize hard carbon with enhanced sodium storage capacity and initial Coulombic efficiency (ICE). By the cross‐linking polymerization between sucrose and lignite coal, the obtained hard carbons possess extensive pseudo‐graphitic regions which facilitate Na‐ion storage and transportation, as well as fewer surface defects that guarantee high ICE.