人造石墨負極材料表面改質對鋰離子電池之電性影響

Electrical Effect of Surface Modification on Artificial Graphite Anode Materials as Lithium Ion Battery

吳玉祥(Yu-Shiang Wu) ； 洪雅純(Ya-Chuen Hung)

《中華科技大學學報》 53期 (2012/10) Pp. 61-79

https://doi.org/10.7095/JCUST.201210.0061

摘要

由於人造石墨擁有高倍率充放電之優異特性，但礙於其電容量較低，所以將人造石墨進行氧化及酸洗之表面改質。本研究以不同氧化及酸洗之水溶液，將人造石墨攪拌並靜置於溶液中兩天，來達到表面改質的目的，改善鋰離子電池負極材料表面結構與電化學特性，並降低充放電中第一次不可逆性與電容量衰退。實驗以硫酸（H2SO4）、磷酸（H3PO4）、高鐵酸鉀（K2FeO4）的氧化及鹽酸（HCl）、氫氟酸（HF）的酸洗與王水（HNO3+3HCl）的氧化酸洗之水溶液作為改質材料，其濃度分別為1M、1 M、0.2 M、1 M、1 M、10 vol.％，來達到改質的目的。以X光繞射分析（XRD）分析改質後人造石墨粉體特性，由層間距d（002）的增加與石墨化度降低，顯示石墨特性的改變；經由王水改質後之人造石墨，電性測試結果最為優異，擁有第一次放電電容量354mAh/g，高於未改質之石墨328mAh/g，第一次不可逆性由14.4％降低至13％，於0.2C充電5C放電仍有329mAh/g之電容量，有效改善其高倍率的電容量。

關鍵字

鋰離子電池 ； 人造石墨 ； 負極材料 ； 表面改質

並列摘要

Although the artificial graphite has this excellent characteristic of high rate charge and discharge, it has low electricity capacity. Therefore, using oxidation and acid-wash the surface of artificial graphite were implemented to modify its characteristic. In this research various oxidation and acid solution were used to mix with the artificial graphite and then left in a static condition for two days. The following results were achieved after the artificial graphite surface characteristic was changed. It improved the stability of the surface structure and the electrochemical properties of anode materials in Li-ion battery. It also helped to reduce the first irreversibility and capacity fading during charge and discharge. The following acid solutions used were, sulfuric acid (H2SO4), phosphoric acid (H3PO4), potassium ferrate (K2FeO4) oxide and hydrochloric acid (HCl), hydrofluoric acid (HF), aqua regia (HNO3+3HCl), for modification of the material structure. The various levels of concentration used were 1 M, 1 M, 0.2 M, 1 M, 1 M, 10 vol.%. The artificial graphite was mixed with these solutions to achieve the said modification. The analysis of graphite characteristics using X-ray diffraction (XRD) showed that an increase in the distance d(002) between layers is related to a decrease in graphitization. This demonstrated the change in the characterization of graphite. After the artificial graphite was modified by aqua regia, it gave the best electric result. Its first discharge capacity was 354 mAh/g, higher than that of the unmodified graphite at 328 mAh/g. Furthermore, the initial irreversibility has dropped from 14.4 % to 13 %. While at 0.2C charge 5C discharge, the capacity is still 329 mAh/g. This demonstrated surface modification has effectively improved the high rate of electrical capacity.

並列關鍵字

lithium-ion batteries ； artificial graphite ； anode material ； surface modification