Effect of ultra-fast pyrolysis on polymer-derived SiOC aerogels and their application as anodes for Na-ion batteries

In the last decade, Sodium-Ion-Batteries (SIB) started to gain interest as a possible complementary candidate to support the overburdened lithium technology, but the manufacturing of a proper anode material is one of the challenging factors for the development of performing SIB. Among others, porous polymer-derived ceramics have been widely explored as suitable anodes despite the production of such materials being time and energy-consuming. In this work, we investigate the feasibility of adopting a low-cost ultra-fast high-temperature pyrolysis for the ceramic conversion of a polymer-derived SiOC aerogel to be employed as anode material. A comprehensive study including N2 physisorption, 29Si MAS NMR and Raman spectroscopy provides the insights of the effect of ultra-fast and conventional heating rates (i.e., 200 °C·s−1 vs. 5 °C·min−1) on the microstructural features and ceramic yield of the SiOC aerogels. As a consequence of the ultra-fast heating rate, a compositional drift towards oxygen-rich SiOC is observed and discussed. The electrochemical performance of both ceramics has been tested and related to the observed compositional differences, revealing a stable capacity of 103 mAh·g−1 for the ultra-fast pyrolyzed SiOC anode, and 152 mAh·g−1 for SiOC ceramized at 5 °C·min−1. Schematic representation of the ultra-fast pyrolysis (UFP) furnace used for this work showing the structure of the ceramic resulting from the ultra-fast heat treatment. [Display omitted]