- 學位論文
奈米矽/碳複合材料應用於鋰離子電池負極材料合成與特性分析
Synthesis and characterization of different carbon materials-modified nano-Si/C composite anode materials for lithium-ion batteries
摘要
近年來，隨著鋰電池技術的飛速發展，它的應用範圍已不僅限於3C產品，而是擴展到手工具、油電混合車、電動車等高功率需求的領域，甚至可以結合再生能源，將多餘的電能儲存起來以供給所需電力，為因應需求，高電容密度及高工作電壓的鋰電池開始蓬勃發展。起初，鋰電池主要使用鋰金屬作為負極，但其充電過程中可能出現的安全隱患促使研究人員轉向以碳材料為負極的第二代鋰離子電池，儘管碳材料安全性高，但其電容量有限，因此目前的研究主要集中在開發能取代碳材料、具有更高電容量的負極材料系統上。 此研究為使用高溫燒結的方式進行奈米矽與酚醛樹脂衍生硬碳複合，而硬碳為十分穩定之材料，添加奈米矽可提升電容量，不過複合奈米矽後體積膨脹以至於結構崩解，成效不如預期，因此再利用瀝青包覆得到HC@Si-P之產物，瀝青可緩衝奈米矽的體積膨脹，並以電流密度1.0 A/g進行200圈充放電，衰退率僅0.16%，此外再利用二氧化碳捕捉的回收碳取代硬碳的部分，奈米矽可嵌入回收碳奈米碳纖維的材料結構中抑制體積膨脹，再使用瀝青包覆更能夠加強抑制效果，稱此材料為RC@Si-P，首圈庫侖效率可達78.15%，在電流密度為0.1 A/g時，電容量為645 mAh/g，甚至相較於石墨之電容量高出許多。除此之外，近幾年鈉電池由於具有蘊藏量豐富、安全性高與環境友善等優點，逐漸受到大家的關注，因此在此研究中將回收碳進行磷摻雜，以提高鈉電池的電容量以及常循環壽命。本實驗使用X光繞射儀(XRD)、X射線能量分佈儀(EDS)、掃描式電子顯微鏡(SEM)和穿透射電子顯微鏡(TEM)，以及充電/放電測試、倍率性能、交流阻抗和循環壽命等電性測試。
並列摘要
In recent years, with the rapid development of lithium battery technology, its applications have expanded beyond 3C products to include hand tools, hybrid vehicles, electric vehicles, and other high-power demand areas. It can even be combined with renewable energy to store excess electricity for power needs. To meet this demand, lithium batteries with high energy density and high operating voltages have begun to flourish. Initially, lithium batteries mainly used lithium metal as the negative elecFtrode, but safety hazards during the charging process prompted researchers to turn to the second generation of lithium-ion batteries with carbon materials as the negative electrode. Although carbon materials are safe, their capacity is limited, so current research is mainly focused on developing negative electrode material systems that can replace carbon materials and have higher capacity. This study involves the use of high-temperature pyrolysis to create nano-silicon and phenolic resin-derived hard carbon composites. Hard carbon is a very stable material and the addition of nano-silicon can increase capacity. However, the volume expansion after composite nano-silicon leads to structural collapse, resulting in less than expected effectiveness. Therefore, the product HC@Si-P is obtained by recycling asphalt to encapsulate it. Pitch can buffer the volume expansion of nano silicon, and 200 charge and discharge cycles are carried out at a current density of 1.0 A/g, with a decay rate of only 0.16%. Furthermore, using carbon captured from CO2 to replace part of the hard carbon, nano-silicon embedded in the material structure of recycled carbon nano fibers can inhibit volume expansion. The use of pitch encapsulation can further enhance this inhibitory effect, and this material is named RC@Si-P. The first cycle coulombic efficiency can reach 78.15% and at a current density of 0.1 A/g, the capacity is 645 mAh/g, even much higher than that of graphite. In addition, in recent years, sodium batteries have gradually attracted attention due to their abundant reserves, high safety, and environmental friendliness. Therefore, in this study, recycled carbon is phosphorus-doped to improve the capacity and cycle life of sodium batteries. X-ray diffraction (XRD), X-ray energy dispersive spectrometer (EDS), scanning electron microscope (SEM), transmission electron microscope (TEM), as well as charge/discharge tests, rate capability, alternating current impedance, and cycle life tests were used in this experiment to test electrical properties.