合成石墨烯複合陽極材料以應用於鋰離子電池

Synthesis of Graphene-based Anodes for Lithium-ion Batteries

林錡沅(Chi-Yuan Lin)

指導教授 ： 謝建德

元智大學/工程學院/化學工程與材料科學學系/碩士(2012年)

摘要

本研究分三部分：第一部分嘗試利用氧化錳奈米粒子(MnO)嵌入石墨烯奈米薄片(Graphene nanosheets, GNs)中探討其鋰離子電池之電性表現；而第二部分則探討了不同結構的奈米銀金屬嵌入GNs中之鋰離子電池電性表現；第三部分研究六方纖鋅礦之奈米氧化鋅顆粒嵌入GNs中之鋰離子電池電性表現。
第一部分研究，MnO利用簡單的液相化學法結合熱還原法合成氧化錳/石墨烯複合陽極材料。在GNs上均勻分佈的MnO經由穿透式電子顯微鏡觀察得之約20-40 nm左右。氧化錳/石墨烯複合陽極材料在0.2 C的充放電速率下提供了635 mAh/g的可逆電容量。石墨烯在這其中扮演了一個緩衝效應(Buffer effect)的角色，使其複合材料擁有高庫倫效率(92.7%)及高電容量維持率(Capacity retention (5 C/0.2 C)>70%)，此優越的性能表現說明了氧化錳/石墨烯複合陽極材料在鋰離子電池方面的應用為可行的。
第二部分研究，利用微波輔助法合成不同奈米結構之奈米銀金屬，接著利用液相化學法結合熱還原法合成奈米銀粒顆粒/石墨烯(Ag-NP-GN)及奈米銀線/石墨烯(Ag-NW-GN)複合材料。奈米銀顆粒粒徑大小約80-100 nm之間，奈米銀線直徑約100 nm。Ag-NW-GN在0.1 C的充放電速率下提供了1723 mAh/g的高充電電容量及較低的不可逆電容量，且高電容量維持率((5 C/0.1 C)>65%)。
第三部分研究，利用微波輔助法合成六方纖鋅礦結構之氧化鋅納米顆粒，接著利用濕式化學法與熱還原法合成氧化鋅/石墨烯(GN-ZnO)複合陽極材料。氧化鋅顆粒粒徑約100 nm。GN-ZnO-1在0.1C的充放電速率下提供了1048 mAh/g的高充電電容量及較低的不可逆電容量，且高電容量維持率((5 C/0.1 C)>60%)。

關鍵字

石墨烯奈米薄片 ； 氧化錳 ； 奈米銀 ； 氧化鋅 ； 陽極 ； 鋰離子電池

並列摘要

This research can be divided into three parts: the intercalation of (1) MnO nanoparticles, (2) Ag nanoparticles and nanowires, and (3) ZnO nanoparticles into graphene nanosheets (GNs), forming three-dimensional hybrids as anode materials for high-performance Li-ion batteries.
(1) A composite of GNs supported by MnO nanocrystals has been fabricated through a simple chemical-wet impregnation followed by the thermal reduction route. The hybrid contains of MnO nanoparticles with an average size of 20-40 nm uniformly dispersed on GNs as observed by transmission electron microscopy. The MnO/GN composite anode delivers a reversible capacity of 635 mAh/g at 0.2 C. The GN plays a buffer effect role in this hybrid material that improves the Coulombic efficiency (92.7%) at the 1st cycle and rate capacity (capacity retention (5 C/0.2 C)>70%). This illustrates the superior performance of MnO/GN composite anode in Li-ion batteries.
(2) An efficient microwave synthesis was employed to fabricate different structures of Ag nanostructures, i.e., nanoparticles and nanowires. The simple chemical-wet impregnation followed by the thermal reduction route was adopted to prepare Ag nanoparticles/GN (Ag-NP-GN) and Ag nanowires/GN (Ag-NW-GN) anode materials. The Ag-NW-GN composite anode material delivers a high capacity of 1723 mAh/g at 0.1 C, a low irreversible capacity at 1st cycle, and an improved rate capability (capacity retention (5 C/0.1 C) > 65%) as well.
(3) The hexagonal ZnO nanoparticles were synthesized by using the microwave-assisted method. Again, the simple chemical-wet impregnation followed by the thermal reduction route was applied to fabricate ZnO nanoparticles/GN (GN-ZnO) composite anode materials. The hybrid, consisted of as-grown ZnO nanoparticles with an average size of 100 nm, exhibits a well-defined wurtzite crystal structure. Experimental result showed that the GN-ZnO composite anode displays a high capacity of 1048 mAh/g at 0.1 C, a low irreversible capacity at 1st cycle, and an enhanced rate capability (capacity retention (5 C/0.1 C) > 60%) as well.

並列關鍵字

Zinc oxide ； Anode ； Lithium-ion battery ； Graphene nanosheets ； Manganese oxide ； Silver

參考文獻

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