The implementation of high capacity silicon-based anodes in lithium-ion batteries is mitigated by the structural and interphase chemical instability posed by a large volumetric change of silicon upon lithiation and delithiation, which can lead to electrode pulverization, loss of electrical contact and formation of new solid electrolyte interphase layers. Silicon monoxide may offer an effective alternative to pure silicon by reducing the coefficient of volumetric expansion from 3.7 to 2 upon full lithiation. Herein, we report the synthesis of novel asymmetric sandwich nanoporous membranes containing micron-sized silicon monoxide particles (≈1 µm) to accommodate the large volume expansion (≈200%) of silicon monoxide during the lithiation and de-lithiation processes. These silicon monoxide membranes were prepared using a facile phase-inversion method and systematically characterized using Scanning Electron Microscopy, Transmission Electron Microscopy, Surface Area Analyzer, Thermogravimetric Analyzer, Raman Spectroscopy, and Powder X-Ray Diffraction. As fabricated membranes were glued directly onto copper current collectors and assembled into half-cell lithium-ion batteries, it was found that asymmetric membranes carbonized at 500C offered the greatest capacity retention with an initial reversible capacity of 526 mAh/g based on the mass of membrane. The method of KOH etching is currently being evaluated to further improve the cycling performance by generating extra void space to accommodate the large volume change. The outstanding cycling performance is attributed to the unique network of nanopores and micropores where silicon monoxide particles are embedded within. Finally, it shall be pointed out that these membranes can be produced in large scale because the overall process is fully compatible with the conventional roll-to-roll membrane technology.

Silicon monoxide nanoporous membranes for lithium ion battery anode

255th National Meeting (2018)

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