优化碳质涂层以消除高性能硅阳极的电化学界面极化  

Optimizing the carbon coating to eliminate electrochemical interface polarization in a high performance silicon anode for use in a lithium-ion battery

作　　者：齐志燕 戴丽琴 王哲帆 谢莉婧[1] 陈景鹏 成家瑶 宋歌 李晓明[1] 孙国华[1] 陈成猛[1,3] QI Zhi-yan;DAI Li-qin;WANG Zhe-fan;XIE Li-jing;CHEN Jing-peng;CHENG Jia-yao;SONG Ge;LI Xiao-ming;SUN Guo-hua;CHEN Cheng-meng(CAS Key Laboratory of Carbon Materials,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China;University of Chinese Academy of Sciences,Beijing 100049,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院山西煤炭化学研究所,中国科学院炭材料重点实验室,山西太原030001 [2]中国科学院大学,北京100049 [3]中国科学院大学材料科学与光电工程中心,北京100049

出　　处：《新型炭材料》2022年第1期245-258,共14页New Carbon Materials

基　　金：2020年山西省关键核心技术和共性技术研发攻关专项(2020XXX014);国家重点研发计划(2020YFB1505800).

摘　　要：有序碳和无序碳都普遍被用作硅(Si)的复合材料。但是具有不同结晶度和孔结构的碳对硅基负极电化学性能的影响仍存在争议。本工作在严格控制碳含量和表面官能团的基础上,选择沥青(Pitch)和酚醛树脂(PR)作为有序碳和无序碳的前驱体,制备了硅碳复合材料(Si@C)并系统地研究了其电化学行为。有序的晶体结构有利于复合物中的电子传输,中孔和大孔有利于锂离子的扩散。具有有序结构和小孔容的碳质涂层为Si的膨胀提供了很好的缓冲,电极在50次循环后仍保持结构完整性。然而,无序和多孔的结构降低了结构的稳定性并产生了很大的极化,这使得循环过程中体积不断膨胀,导致电化学性能较差。Si@C-Pitch在5 A g^(−1)下的容量是Si@C-PR的8倍,在0.5 A g^(−1)下100次循环后的容量保持率是Si@C-PR的1.9倍。该研究可为Si@C负极中炭材料的选择提供了理论指导。Ordered and disordered carbons have been commonly used as coating materials for silicon(Si) anodes, however the effect of carbons with different crystallinities and pore structures on their electrochemical performance remains controversial. We used pitch and phenolic resin(PR) as the precursors of ordered and disordered carbon, respectively, to prepare carbon-coated silicon(Si@C) with strictly controlled carbon contents and surface functional groups. Their electrochemical behavior was investigated. An ordered crystalline structure is favorable for electron transport, and mesopores and macropores are conducive to the diffusion of lithium ions. Such a coating with a small pore volume is an excellent buffer for the expansion of Si, and the electrode maintains structural integrity for 50 cycles. A disordered porous structure is less robust and produces a large polarization, which produces continuous volume expansion with cycling and leads to inferior electrochemical performance. As a result, the capacity and capacity retention after 100 cycles at 0.5 Ag^(−1) of Si@C-Pitch are respectively 8 times and 1.9 times those of Si@C-PR. This study provides theoretical guidance for the selection of carbon materials used in Si@C anodes.

关 键 词：硅碳复合物 晶体结构 孔结构 失效机制 极化 

分 类 号：TB33[一般工业技术—材料科学与工程]