CAJ | 학술논문

以天然鳞片石墨为原料,利用电泳插层法制备出具有适当膨胀体积的微膨石墨,石墨的结构缺陷增多,具有较大的比表面积和增大的石墨层间距. 微膨石墨的可逆容量可以达到521 mAh/g;在0. 2 C倍率循环充放电30次容量最佳可保持在99%以上,在1. 0 C循环50次其容量可稳定在188 mAh/g,且表现出良好的倍率性能. 微膨石墨电化学性能的改善得益于其具有适当的比表面积及内部结构的改变. 交流阻抗测试显示微膨石墨的SEI膜阻抗和电荷传递阻抗小于鳞片石墨,具有良好的电化学活性.
이천연린편석묵위원료,이용전영삽층법제비출구유괄당팽창체적적미팽석묵,석묵적결구결함증다,구유교대적비표면적화증대적석묵층간거. 미팽석묵적가역용량가이체도521 mAh/g;재0. 2 C배솔순배충방전30차용량최가가보지재99%이상,재1. 0 C순배50차기용량가은정재188 mAh/g,차표현출량호적배솔성능. 미팽석묵전화학성능적개선득익우기구유괄당적비표면적급내부결구적개변. 교류조항측시현시미팽석묵적SEI막조항화전하전체조항소우린편석묵,구유량호적전화학활성.
Expanded flake graphites ( EFGs) with different expansion volumes were prepared by an electrophoresis intercalation method using natural flake graphite as the raw material, concentrated HNO3 and acetic anhydride as intercalates and KMnO4 as oxi-dant. Results indicate that the density of structural defects, and the surface area and d002 increase after the intercalation. EFG-0. 7 ob-tained with a KMnO4 mass percentage of 0. 7 wt% has a capacity of 521 mAh/g when used as the anode of a lithium ion battery, which is significantly higher than the theoretical capacity of natural graphite. EFG-0. 7 retains more than 99% of its capacity after 30 cycles at 0. 2 C and its capacity stabilizes at 188 mAh/g after 50 cycles at 1. 0 C. All the EFGs exhibit excellent performance in high-rate charge-discharge. The resistance of the solid-electrolyte interface film and the charge transfer resistance of the EFGs are smaller than natural flake graphite as revealed by electrochemical impedance spectroscopy. The improved electrochemical perform-ance of the EFGs can be ascribed to their increased surface area and d002 , and the larger number of structural defects.