Suzuki Satoshi, Mazej Zoran, Zemva Boris, Ohzawa Yoshimi, Nakajima Tsuyoshi
Acta Chim Slov. 2013;60(3):513-20.
Surface lattice defects would act as active sites for electrochemical reduction of propylene carbonate (PC) as a solvent for lithium ion battery. Effect of surface chlorination of natural graphite powder has been investigated to improve charge/discharge characteristics of natural graphite electrode in PC-containing electrolyte solution. Chlorination of natural graphite increases not only surface chlorine but also surface oxygen, both of which would contribute to the decrease in surface lattice defects. It has been found that surface-chlorinated natural graphite samples with surface chlorine concentrations of 0.5-2.3 at% effectively suppress the electrochemical decomposition of PC, highly reducing irreversible capacities, i.e. increasing first coulombic efficiencies by 20-30% in 1 mol L-1 LiClO4-EC/DEC/PC (1:1:1 vol.). In 1 mol L-1 LiPF6-EC/EMC/PC (1:1:1 vol.), the effect of surface chlorination is observed at a higher current density. This would be attributed to decrease in surface lattice defects of natural graphite powder by the formation of covalent C-Cl and C=O bonds.
表面晶格缺陷可作为碳酸丙烯酯（PC）电化学还原的活性位点，碳酸丙烯酯是锂离子电池的一种溶剂。研究了天然石墨粉表面氯化对含PC的电解质溶液中天然石墨电极充放电特性的影响。天然石墨的氯化不仅增加了表面氯含量，还增加了表面氧含量，这两者都有助于减少表面晶格缺陷。研究发现，表面氯浓度为0.5-2.3 at%的表面氯化天然石墨样品能有效抑制PC的电化学分解，大幅降低不可逆容量，即在1 mol L-1 LiClO4-EC/DEC/PC（1:1:1体积比）中，首次库仑效率提高20-30%。在1 mol L-1 LiPF6-EC/EMC/PC（1:1:1体积比）中，在更高的电流密度下观察到表面氯化的效果。这归因于通过形成共价C-Cl键和C=O键减少了天然石墨粉的表面晶格缺陷。
