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Improved electrochemical stability of the graphite anode by introducing semi-ionic C-F bond
김경훈,안동해,노의영,임지선,이영석 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
A lithium fluoride (LiF), formed with lithium ion and fluorine ion, is one of the SEI components and thermally and chemically stable for the Lithium ion battery (LIB). In this study, the two types of C-F bonds presented as (SI) and covalent (CV) types were introduced on the graphite surface to investigate which one has main factor to form the LiF after charging step and to has more cycle stability. Disassembled anode surface after charge-discharge cycles was investigated by X-ray photoelectron spectroscopy of F1s deconvolution to confirm the LiF content. The graphite with semi-ionic C-F bonds (GSI) has 29% fluorine on the surface (pristine: 5%, graphite with CV C-F bonds (GCV): 4%) and the most fluorine on the graphite surface is formed as LiF. To evaluate the cycle stability, assembled coin-cell was charge-discharge steps for 100 cycle at 1 C-rate. The retention between first and 100th discharge capacity of GSI is 98.9% (pristine: 89.8%, GCF: 91.7%).
Facile preparation of mesoporous SiOx/C microsphere for an anode material of Li ion battery
류재춘,김경훈,노의영,이진배,이영석 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
Many efforts have been devoted to the development of the anode electrode materials of lithium-ion batteries (LIBs) with high capacity. Silicon sub-oxides (SiOx) has attracted great interest due to its high theoretical capacity (4200 mA h g<sup>-1</sup>). However, SiOx is limited by its low conductivity and large volume change. To solve this disadvantage, SiOx/C composites to give high lithium storage performance have been suggested. In this study, we suggested a facile and economic preparation method of mesoporous SiOx/C microsphere using petroleum pitch as a cheap carbon source. We synthesized the mesoporous SiO<sub>2</sub> microsphere (MSM) using modified Stöber process. The MSM was coated with petroleum pitch by chemical vapor deposition and then heat-treated in range of 600-900℃. We tested the lithium storage performance of as-prepared SiOx/C microsphere as an anode material of LIB. The results showed that the prepared SiOx/C microsphere had high capacity and cycling stability for lithium storage.