双功能活化制备沥青基硬炭用于钠离子电池负极  

Preparation of pitch-based hard carbon by bi-functional activation strategy for sodium-ion batteries

作　　者：吴吉昊 陈涛 刘思宇 刘梦柯 杨卷 WU Jihao;CHEN Tao;LIU Siyu;LIU Mengke;YANG Juan(School of Chemical Engineering,Xi’an Jiaotong University,Xi’an 710049,Shaanxi,China)

机构地区：[1]西安交通大学化工学院,陕西西安710049

出　　处：《化工学报》2024年第3期1019-1027,共9页CIESC Journal

基　　金：国家自然科学基金项目(22278328);陕西省重点研发计划项目(2023-YBGY-292)。

摘　　要：硬炭作为钠离子电池(SIBs)最具有应用前景的负极材料,其形貌的可控调节和结构优化被广泛研究和关注。以煤沥青为原料,采用柠檬酸钾(C_(6)H_(5)K_(3)O_(7)·H_(2)O)作为双功能活化剂:(1)气体分解产物可消耗过量的氢,实现沥青的固态热解,阻碍有序微晶的生成;(2)固态分解产物钾盐进行活化造孔,从而在高温碳化过程中形成丰富的封闭纳米孔。基于此,成功制备了具有高度无序、多孔片状结构的沥青基硬炭材料,并应用于SIBs负极,探究其电化学性能。研究发现,通过调控活化剂用量可以实现沥青基硬炭微观结构的优化,在适宜质量比条件下制备的硬炭(HC-2-1300)首次库仑效率高达81.5%,在0.1 A·g^(-1)的电流密度下,其可逆比容量为214.2 mAh·g^(-1),明显优于直接碳化的样品(DC-1300)。同时,在5 A·g^(-1)的高电流密度下,HC-2-1300样品仍有116.7 mAh·g^(-1)的可逆比容量,且在1 A·g^(-1)电流密度下充放电循环2000圈后,容量保持率达75.1%,显现出优异的倍率性能和循环稳定性,具有广阔的应用前景。As the most promising anode material for sodium-ion batteries(SIBs),hard carbon has been widely studied and focused on its controllable adjustment of morphology and structural optimization.Herein,a novel bifunctional activation strategy was developed to prepare the hard carbon materials with highly disordered structures as anode for SIBs by using coal tar pitch as precursors with the help of potassium citrate monohydrate(C_(6)H_(5)K_(3)O_(7)·H_(2)O).It is believed that the C_(6)H_(5)K_(3)O_(7)·H_(2)O has a dual role:(1)its gas decomposition products can consume excessive hydrogen and further realize solid pyrolysis of pitch precursors,preventing the formation of ordered microcrystals;(2)the solid decomposition products(potassium salt)act as activating agents to introduce rich closed nanopores into the carbon matrix during high-temperature carbonization.Interestingly,the microstructure of pitch-based hard carbon can be optimized by tuning the amount of activating agents.Furthermore,the electrochemical performance investigations revealed that the as-optimized hard carbon(HC-2-1300)delivers a reversible specific capacity of 214.2 mAh·g^(-1)at 0.1 A·g^(-1)with an initial coulombic efficiency of as high as 81.5%,which is superior to sodium-ion batteries[J].CIESC Journal,2024,75(3):1019-1027 that of directly carbonized samples(DC-1300).In addition,there is still a high reversible specific capacity of 116.7 mAh·g^(-1)at 5 A·g^(-1)and good cycling stability with a capacity retention rate of 75.1%over 2000 cycles,highlighting the great potential of pitch-based hard carbon anodes for SIBs.

关 键 词：钠离子电池 沥青基硬炭 双功能活化剂 电化学性能 

分 类 号：TQ536.4[化学工程—煤化学工程]