| 摘要: | 本研究的第一部分，首先比較離子液體0.8 m LiFSI/PMP-FSI與傳統碳酸酯類電解質1 M LiPF6/EC-DEC應用在高電壓LiNi0.5Mn1.5O4/Li半電池中。0.8 m LiFSI/PMP-FSI電解質在熱穩定性及浸泡實驗中皆能得到較1 M LiPF6/EC-DEC好的表現；但是，在高電壓環境下0.8 m LiFSI/PMP-FSI會發生鋁腐蝕的問題，使其無法應用於LiNi0.5Mn1.5O4的材料中。
延續第一部分的結果，在第二部分針對0.8 m LiFSI/PMP-FSI改質。首先提高鋰鹽濃度來嘗試抑制鋁腐蝕反應。發現鋰鹽濃度愈高，愈能抑制鋁腐蝕反應，但3.2 m LiFSI/PMP-FSI為最大溶解濃度也無法完全抑制鋁腐蝕，故需需要尋找其他方法解決鋁腐蝕問題。
在第二部分發現提高鋰鹽濃度確實能改善鋁腐蝕問題，但仍無法完全抑制。故在第三部分加入TFSI陰離子期望能得到更好的結果，相比純FSI-based離子液體，加入TFSI陰離子後的鋁腐蝕反應明顯降低，在0.8 m LiFSI/FT 13的條件下可解決鋁腐蝕問題。但發現其在高速充放電及graphite負極中電性表現較純FSI-based離子液體來的差，故本研究期望能在改善配方已得到最佳的電性表現。
在第四部分，結合第二及第三部分的研究，同時提高Li及TFSI濃度，發現在TFSI比例較低的配方下即可抑制鋁腐蝕問題，其中2.4 m LiTFSI/PMP-FSI雖然在抑制鋁腐蝕方面略遜於0.8 m LiFSI/FT 13，但在高速充放電及graphite負極中表現較好。
;In the first part of the study, we first compared the ionic liquid 0.8 m LiFSI/PMP-FSI with the traditional carbonate electrolyte 1 M LiPF6/EC-DEC in a high voltage LiNi0.5Mn1.5O4/Li half-cell. 0.8 m LiFSI/PMP-FSI electrolytes can achieve better performance than 1 M LiPF6/EC-DEC in thermal stability and immersion experiments; however, aluminum corrosion occurs at 0.8 m LiFSI/PMP-FSI in high voltage environments. The problem is that it cannot be applied to LiNi0.5Mn1.5O4.
Continuing the results of the first part, the second part was modified for 0.8 m LiFSI/PMP-FSI. First, increase the lithium salt concentration to try to suppress the aluminum corrosion reaction. It is found that the higher the lithium salt concentration, the more the aluminum corrosion reaction can be inhibited, but the 3.2 m LiFSI/PMP-FSI is the maximum dissolved concentration and can not completely inhibit the aluminum corrosion. Therefore, it is necessary to find other methods to solve the aluminum corrosion problem.
In the second part, it was found that increasing the lithium salt concentration did improve the aluminum corrosion problem, but it could not be completely suppressed. Therefore, the addition of TFSI anion in the third part is expected to give better results. Compared with the pure FSI-based ionic liquid, the aluminum corrosion reaction after adding the TFSI anion is significantly reduced, and the aluminum corrosion can be solved under the condition of 0.8 m LiFSI/FT 13. However, it was found that its electrical performance in high-speed charge and discharge and graphite anodes is worse than that of pure FSI-based ionic liquids. Therefore, this study is expected to obtain the best electrical performance in improving the formulation.
In the fourth part, combined with the second and third parts of the study, while increasing the concentration of Li and TFSI, it was found that the aluminum corrosion problem can be suppressed under the formulation with a lower TFSI ratio, of which 2.4 m LiTFSI/PMP-FSI is inhibiting aluminum. Corrosion is slightly inferior to 0.8 m LiFSI/FT 13, but it performs better in high-speed charge and discharge and graphite anode. |
