Hard X-ray Photoelectron Spectroscopy (HAXPES) Investigation of the Silicon Solid Electrolyte Interphase (SEI) in Lithium-Ion Batteries

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• 作者：Benjamin T. Young ; David R. Heskett ; Cao Cuong Nguyen ; Mengyun Nie ; Joseph C. Woicik ; Brett L. Lucht
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：September 16, 2015
• 年：2015
• 卷：7
• 期：36
• 页码：20004-20011
• 全文大小：442K
• ISSN：1944-8252

文摘

Binder-free silicon (BF-Si) nanoparticle anodes were cycled with 1.2 M LiPF₆ in ethylene carbonate (EC), fluoroethylene carbonate (FEC), or EC with 15% FEC (EC:FEC), extracted from cells and analyzed by Hard X-ray Photoelectron Spectroscopy (HAXPES). All of the electrolytes generate an SEI which is integrated with Si containing species. The EC and EC:FEC electrolytes result in the generation of Li_xSiO_y after the first cycle while Li_xSiO_y is only observed after five cycles for the FEC electrolyte. The SEI initially generated from the EC electrolyte is primarily composed of lithium ethylene dicarbonate (LEDC) and LiF. However, after five cycles, the composition changes, especially near the surface of silicon because of decomposition of the LEDC. The SEI generated from the EC:FEC electrolytes contains LEDC, LiF, and poly(FEC) and small changes are observed upon additional cycling. The SEI generated with the FEC electrolyte contains LiF and poly(FEC) and small changes are observed upon additional cycling. The stability of the SEI correlates with the observed capacity retention of the cells.