Tailoring the microstructure of bamboo-derived hard carbon to realize high sodium storage  

调控竹制硬碳微观结构助力钠离子电池高效储钠

作　　者：YU Xin GUO Hua-jun WANG Zhi-xing LI Jia-yi YAN Guo-chun LI Guang-chao WANG Jie-xi 于鑫;郭华军;王志兴;李嘉翌;颜果春;李广超;王接喜(School of Metallurgy and Environment,Central South University,Changsha 410083,China;Engineering Research Center of the Ministry of Education for Advanced Battery Materials,Central South University,Changsha 410083,China;Hunan Provincial Key Laboratory of Nonferrous Value-Added Metallurgy,Central South University,Changsha 410083,China;National Engineering Research Centre of Advanced Energy Storage Materials,Changsha 410205,China;Department of Chemistry,University of Washington,Seattle,Washington 98195-1700,United States)

机构地区：[1]School of Metallurgy and Environment,Central South University,Changsha 410083,China [2]Engineering Research Center of the Ministry of Education for Advanced Battery Materials,Central South University,Changsha 410083,China [3]Hunan Provincial Key Laboratory of Nonferrous Value-Added Metallurgy,Central South University,Changsha 410083,China [4]National Engineering Research Centre of Advanced Energy Storage Materials,Changsha 410205,China [5]Department of Chemistry,University of Washington,Seattle,Washington 98195-1700,United States

出　　处：《Journal of Central South University》2024年第12期4497-4509,共13页中南大学学报(英文版)

基　　金：Project(2022RC3048)supported by the Science and Technology Innovation Program of Hunan Province,China;Project support by the Guangdong Greenway Technology Co.Ltd.,China。

摘　　要：Hard carbon is regarded as a promising anode material for sodium-ion batteries,while it remains a huge challenge to initial coulombic efficiency and rate performance.Numerous studies show that critical structural features in hard carbon,namely defects,crystallites,and close pores,are directly responsible for the electrochemical performance in sodium-ion batteries.Here,we employ bamboo-derived hard carbon to systematically regulate the defects and crystallites in hard carbon by introducing mechanical activation.Benefiting from ball milling,the intermediate product with a high specific area more easily transforms into hard carbon,which possesses abundant closed pores,effective interlayer spacing,and suitable sodium storage defects,helping to improve the sodium ion storage performance.As a result,the hard carbon ball milled for 20 min presents a high reversible capacity of 315.2 mA·h/g at 17.5 mA/g with an initial coulombic efficiency up to 79.3%,as well as good rate and cycling performances.硬碳被视为极具前景的钠离子电池负极材料,但是其仍面临着储钠容量较低、倍率性能差等问题。研究表明,硬碳的缺陷和碳层结构情况极大影响其电化学储钠性能。硬碳中的缺陷在提供活性位点吸附储钠的同时,还会影响SEI膜的生成,导致钠离子不可逆存储,因此亟需调控缺陷种类和数量以平衡吸附储钠和不可逆储钠。此外,相比于石墨中排列有序的碳层结构,硬碳中的石墨畴碳层因为有杂原子的存在弯曲折叠,与低电压下嵌入储钠和填孔储钠息息相关,故对于石墨畴大小、层间距和闭孔的调控是增加硬碳储钠容量的重要方式。本研究通过在两次热处理之间引入机械活化,最终系统地调控竹制硬碳中的缺陷和石墨微区等微观结构,促进钠离子有效存储。本研究将500℃煅烧过的中间产物球磨20 min之后,再经过高温碳化,制备出了具有丰富闭孔、有效层间距(0.379 nm)和富含C=O的硬碳材料(BHC-Q 20)。其在17.5 mA/g的电流密度下展现出了315.2 mA·h/g的可逆比容量,即使在1000 mA/g电流密度下也能保持278.8 mA·h/g的比容量,循环100次之后可逆比容量依旧有282.9 mA·h/g,容量保持率达到99.6%。

关 键 词：sodium-ion battery hard carbon cathode ball-milling structural reconstruction closed pore 

分 类 号：TG1[金属学及工艺—金属学]