Vrankovic, Dragoljub and Graczyk-Zajac, Magdalena and Kalcher, Constanze and Rohrer, Jochen and Becker, Malin and Stabler, Christina and Trykowski, Grzegorz and Albe, Karsten and Riedel, Ralf (2017):
Highly Porous Silicon Embedded in a Ceramic Matrix: A Stable High-Capacity Electrode for Li-Ion Batteries.
In: ACS Nano, 11 (11), pp. 11409-11416. ACS Publications, ISSN 1936-0851,
DOI: 10.1021/acsnano.7b06031,
[Article]

Abstract

We demonstrate a cost-effective synthesis route that provides Si-based anode materials with capacities between 2000 and 3000 mAh·g_Si^–1 (400 and 600 mAh·g_composite^–1), Coulombic efficiencies above 99.5%, and almost 100% capacity retention over more than 100 cycles. The Si-based composite is prepared from highly porous silicon (obtained by reduction of silica) by encapsulation in an organic carbon and polymer-derived silicon oxycarbide (C/SiOC) matrix. Molecular dynamics simulations show that the highly porous silicon morphology delivers free volume for the accommodation of strain leading to no macroscopic changes during initial Li–Si alloying. In addition, a carbon layer provides an electrical contact, whereas the SiOC matrix significantly diminishes the interface between the electrolyte and the electrode material and thus suppresses the formation of a solid–electrolyte interphase on Si. Electrochemical tests of the micrometer-sized, glass-fiber-derived silicon demonstrate the up-scaling potential of the presented approach

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