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

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.