Effective Infiltration of Gel Polymer Electrolyte into Silicon-Coated Vertically Aligned Carbon Nanofibers as Anodes for Solid-State Lithium-Ion Batteries

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• 作者：Gaind P. Pandey ; Steven A. Klankowski ; Yonghui Li ; Xiuzhi Susan Sun ; Judy Wu ; Ronald A. Rojeski ; Jun Li
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：September 23, 2015
• 年：2015
• 卷：7
• 期：37
• 页码：20909-20918
• 全文大小：502K
• ISSN：1944-8252

文摘

This study demonstrates the full infiltration of gel polymer electrolyte into silicon-coated vertically aligned carbon nanofibers (Si-VACNFs), a high-capacity 3D nanostructured anode, and the electrochemical characterization of its properties as an effective electrolyte/separator for future all-solid-state lithium-ion batteries. Two fabrication methods have been employed to form a stable interface between the gel polymer electrolyte and the Si-VACNF anode. In the first method, the drop-casted gel polymer electrolyte is able to fully infiltrate into the open space between the vertically aligned core鈥搒hell nanofibers and encapsulate/stabilize each individual nanofiber in the polymer matrix. The 3D nanostructured Si-VACNF anode shows a very high capacity of 3450 mAh g^鈥? at C/10.5 (or 0.36 A g^鈥?) rate and 1732 mAh g^鈥? at 1C (or 3.8 A g^鈥?) rate. In the second method, a preformed gel electrolyte film is sandwiched between an Si-VACNF electrode and a Li foil to form a half-cell. Most of the vertical core鈥搒hell nanofibers of the Si-VACNF anode are able to penetrate into the gel polymer film while retaining their structural integrity. The slightly lower capacity of 2800 mAh g^鈥? at C/11 rate and 鈭?070 mAh g^鈥? at C/1.5 (or 2.6 A g^鈥?) rate have been obtained, with almost no capacity fade for up to 100 cycles. Electrochemical impedance spectroscopy does not show noticeable changes after 110 cycles, further revealing the stable interface between the gel polymer electrolyte and the Si-VACNFs anode. These results show that the infiltrated flexible gel polymer electrolyte can effectively accommodate the stress/strain of the Si shell due to the large volume expansion/contraction during the charge鈥揹ischarge processes, which is particularly useful for developing future flexible solid-state lithium-ion batteries incorporating Si-anodes.