改性沥青基硬碳材料的可控制备及其储钠性能

Fabrication of modified pitch-based hard carbon materials for high-performance sodium-ion storage

钠离子电池(SIBs)用碳负极材料的可控制备与结构优化是电化学储能领域研究的热点方向之一。以煤化学工业副产物煤沥青为原料,通过对苯二甲醇化学交联表面改性辅以高温碳化处理,成功制备了改性沥青基硬碳材料,并用于SIBs负极。SEM、TEM、氮气吸脱附测试等表征结果证实,煤沥青的化学交联改性能够有效减缓其高温石墨化进程,进一步增大层间距(0.373 nm)和碳层的无序度,同时获得的硬碳材料颗粒尺寸由15μm减小至约2μm。电化学测试结果表明,所制备的改性沥青基硬碳材料(HC-1300)首次库伦效率高达80.1%,在电流密度为0.1 A/g时,其比容量为232.2 mAh/g,明显优于直接碳化获得的样品(DC-1300)。此外,在5 A/g高电流密度下,HC-1300样品的比容量为171.1 mAh/g,且经1 500圈充放电循环后容量保持率为74.9%,展现出良好的倍率性能和循环稳定性。

The controllable fabrication and structural optimization of carbon anode materials for sodium-ion batteries(SIBs)are one of the leading research directions in the field of electrochemical energy storage.Herein,the coal tar pitch from industrial byproduct was first used as the carbonous precursors to surface modification by a chemical cross-linking reaction of 1,4-benzenedimethanol,and then the hard carbon materials for SIBs were successfully prepared through high-temperature carbonization treatment.Combined with a series of characterization technologies including SEM,TEM,and nitrogen(N2)adsorption/desorption tests,it is confirmed that the chemical cross-linking modification of coal tar pitch could significantly restrain the graphitization degree of carbon materials,and thereby further increase layer spacing(0.373 nm)and carbon layer disorder.Meanwhile,the particle size of the obtained hard carbon material is minimized from 15μm to about 2μm.The electrochemical measurements demonstrate that the modified pitch-based hard carbon mate⁃rial(HC-1300)shows a high initial Coulombic efficiency of 80.1%and a specific capacity of 232.2 mAh/g at 0.1 A/g,which is signifi⁃cantly superior to that of the sample(DC-1300)obtained by direct carbonization.In addition,the HC-1300 sample delivers a specific ca⁃pacity of 171.1 mAh/g at a high current density of 5 A/g and excellent capacity retention of 74.9%after 1500 charging/discharging cy⁃cles,suggesting excellent rate performance and cycling stability.