高容量、安全操作、快速充電/放電和長壽命是鋰離子電池（LIB）在大型儲能應用中的基本特性。具有快速充電/放電需求的電動汽車，這種功率型 LIB 面臨的主要挑戰是開發具有電容量和壽命要求的負極材料。目前聚焦的負極材料為石墨和Li4Ti5O12，但石墨有形成鋰樹枝狀結晶突出物形成的問題，而Li4Ti5O12則有低電容量的問題。鈮基氧化物由於擁有豐富的Nb5+/Nb4+和Nb4+/Nb3+氧化還原化學，且其理論電容量達到200-416 mAh/g，因此近年來對此類ReO3結構的氧化物研究逐漸增加。但由於其電子和離子電導率相對較低，以及穩定性差等缺點，將其落實應用仍需大量研究與分析。
本論文以傳統的高溫固相法製備鈮基氧化物MoNb12O33，將其應用至鋰離子電池之負極材料。為了優化快速充放電性能，將對氧化物起始原料、煆燒溫度、煆燒助劑及碳源披覆等參數進行製程最適化。以Nb2O5為鈮源，MoO2與MoO3為鉬源，在空氣氣氛下，以900 ⁰C/12h的條件煆燒合成MoNb12O33，分別命名為 MNO與 M’NO。藉由定電流充放電性能測試，MNO在1C下的電容量為155 mAh/g，優於M’NO (75 mAh/g)。降低煆燒溫度為降低成本方法之一，氫氧化鋰(LiOH)可作為煆燒助劑，用於降低煆燒溫度，同時也做為摻雜物。添加鋰源後的Li-MNO，其鋰離子嵌脫行為、倍率性能及循環穩定性等電化學性質均受到影響。碳材多用於增加材料的表面電導率，為了獲得氮摻雜碳(Nitrogen-doped carbon)或氮碳披覆的Li-MNO，因此在750 ⁰C/3h的條件下熱裂解三聚氰胺，使其以氮摻雜碳(N-doped carbon)的型態披覆在Li-MNO表面。以EIS分析其表面阻抗變化，含有氮碳披覆之Li-MNO/NC，阻抗低於無氮碳披覆之Li-MNO，顯示NC塗層可以有效增加表面電導率。根據電化學性能分析結果，已優化的10% Li-MNO/NC-4負極材料在此研究中擁有最佳性能。最後，透過改變放電截止電壓，減少Nb3+還原量，可又提升容量保持率與循環壽命。

High capacity, safe operation, fast charge/discharge and long lifetime are the essential properties of lithium-ion batteries for large-scale energy-storage applications for electric vehicles with fast charge/discharge. The major challenge for such power LIBs is to develop an improved anode electrode with the energy and lifetime requirements. The focused anode materials have been graphite and Li4Ti5O12. Graphite has the problem of the formation of Li dendrites, while Li4Ti5O12 suffers the problem of low capacity. Niobium-based oxides have been heavily studied in recent years due to the rich redox chemistry of Nb5+/Nb4+ and Nb4+/Nb3+ to enable high theoretical capacity of 200-400 mAh/g, but it has a poor rate capability resulting from relatively low electronic and ionic conductivity. The niobium-based oxides still need a lot of research and analysis for applying it on energy storage.
In this work, niobium-based oxide material of molybdenum niobium oxide, MoNb12O33 (MNO), was prepared by solid state method as an anode material for lithium-ion battery. To optimize the fast charge-discharge performance, the parameters such as precursors, carbon coating, calcination temperature, and crystallization aid were discussed in this thesis. The precursors of Nb2O5 and MoO¬2 (or MoO3) had been used as the sources of niobium and molybdenum, respectively, for MNO (or M’NO). Initially, oxide precursors were homogeneously mixed and then calcined at 900 ⁰C for 12h in air with a heating rate of 10 ⁰C /min. As shown by galvanostatic discharge-charge performance, the capacity of MNO was found to be 155 mAh/g at 1C, which was higher compared to M’NO of 75 mAh/g at 1C. Due to relatively high calcination temperature, lithium hydroxide (LiOH) was utilized to lower the calcination temperature and also acted as a dopant. Accordingly, the results showed that the lithium-ion intercalation behavior, C-rate performance, and cycle stability were affected by the addition of LiOH. As carbon material has been utilized to enhance the surface conductivity of anode material, melamine, a nitrogen-based organic compound that could form nitrogen-doped carbon (NC) by pyrolysis process, was considered in this work. To obtain NC-coated Li-MNO or Li-MNO/NC, melamine was mixed homogeneously with Li-MNO, then the mixture was pyrolyzed at 750 ⁰C for 3h under Ar atmosphere with a heating rate of 5 ⁰C /min. According to electrochemical impedance spectroscopy (EIS) analysis, the resistance of Li-MNO/NC was found to be lower than that of Li-MNO, which proved that the NC coating could significantly improve the conductivity of the resulted anode material. Briefly, the optimized anode material of 10% Li-MNO/NC-4 exhibited the best performance in this work, as supported with various electrochemical properties. To further improve both capacity retention and cycle lifetime, the discharge cut-off voltage and the Nb3+ content in MNO were optimized.

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