| 摘要: | SiOx具有高容量來儲存鋰，擁有豐富的天然資源並且具有安全性，可作為高能量密度鋰離子電池之負極。然而，鋰離子電池在初次充放電過程中，會消耗活性鋰離子在負極形成一層固態電解質介面（Solid Electrolyte Interface，SEI），導致初始庫倫效率（ICE）降低。因此，此研究的目標是在第一次充放電循環中補償不可逆的鋰離子損失，提高初始庫倫效率（ICE）和充放電容量。我們設計了一種化學浸泡方法來進行預鋰化負極。我們使用不同的芳香族化合物，例如萘（NP）、1-甲基萘（MeNP）、2-苯基酚（BPOH）、2-萘酚（NPOH），與鋰金屬在2-甲基四氫呋喃（Me-THF）或四氫呋喃（THF）溶劑中形成預鋰化溶液。
為了實現更高的初始庫倫效率，我們選擇了1-甲基萘（MeNP）化合物，通過使用推電子官能基，即萘上的甲基，增加電子密度來降低氧化還原電位以增強預鋰化效果。使用MeNP/Me-THF預鋰化溶液，我們發現浸泡20分鐘後，ICE增加至147.2%，開路電壓（OCV）降低至0.29 V。儘管它表現出快速預鋰化的效果，但可逆容量有所減少。因此，我們添加了具有相對較低氧化還原電位和高電子親和力含有O官能基的芳香族化合物，以增加對Li+的吸引力，並在自由基電子和Li+進入SiOx電極時減緩Si-O鍵的破壞。我們比較了添加2-苯基酚（BPOH）或2-萘酚（NPOH）化合物的效果，發現較高的LUMO（最低未占據分子軌道）的化合物效果最好。使用1-甲基萘加10%的2-苯基酚反應20分鐘後，ICE增加至136.5%，可逆容量在不同的充放電速率下都增加。浸泡在含有1-甲基萘加10%的2-苯基酚溶液中的負極，在高速充放電速率為5000 mA/g時，表現出86 mAh/g的可逆容量。
;In this study, we targeted silicon oxide（SiOx）materials as anodes for lithium-ion batteries. SiOx has a high specific capacity to store lithium, abundant natural resources and safety. However, the low initial coulombic efficiency and large volume expansion during cycling lead to the loss of active lithium and a decrease in the coulombic efficiency（CE）of silicon-based materials. Therefore, our goal is to compensate for the irreversible loss of lithium ions during the first charge-discharge cycle. To increase the initial coulombic efficiency（ICE）and charge-discharge capacities, we designed a chemical immersion method for pre-lithiation anodes. We used different aromatic compounds, such as naphthalene（NP）, 1-methylnaphthalene（MeNP）, 2-Phenylphenol（BPOH）, 2-Naphthol（NPOH）, with lithium metal in 2-Methyltetrahydrofuran（Me-THF）or tetrahydrofuran（THF）solvent to form pre-lithiation solutions.
In order to achieve higher initial coulombic efficiency, we chose the 1-methyl naphthalene（MeNP）compound to enhance the pre-lithiation effect by using the electron-donating functional group, the methyl on naphthalene, to decrease the redox potential. With the MeNP/Me-THF pre-lithiation solution, we found that after immersing for 20 minutes, the ICE increased to 147.2%, and the open circuit voltage（OCV）decreased to 0.29 V. Although it exhibited fast pre-lithiation, the reversible capacity was reduced. Therefore, we added aromatic compounds containing functional groups with relatively low redox potential and high electron affinity containing O groups, to increase the attraction to Li+ and slow down the breaking of Si-O bonds when anions and Li+ entered the SiOx electrode. We compared the effects of adding 2-phenylphenol（BPOH）or 2-naphthol（NPOH）compounds and found that the higher LUMO molecule had the best effect. Using 1-methyl naphthalene with 10% of 2-phenylphenol reacted for 20 minutes, the ICE increased to 136.5%, and the reversible capacity increased at various charge-discharge rates. The anode, immersed in a solution containing 1-methyl naphthalene and 10% 2-phenylphenol, exhibits a reversible capacity of 86 mAh/g at a high-speed charge-discharge rate of 5000 mA/g. |
