Kill Two Birds with One Stone: Multifunctional Porous SiOC–Fe₂O₃ Composite for Li Ion Energy Conversion and Electromagnetic Wave Absorption

It is necessary to design a scalable composite material with a rational structure for Li-ion batteries and electromagnetic wave absorption. Herein, we developed a modified precursor-driven method of spacer-assisted oxidation to prepare heterogeneous multi-interface SiOC-based composite ceramic nanoparticles. The outstanding structural design regulated by the ratio of raw materials tailored its functional potential in the fields of Li-ion batteries and electromagnetic wave absorption. The addition of a small amount of iron-sol produced small-sized ceramic nanoparticles bridged by carbon ribbons, which can provide efficient charge transfer kinetics and volumetric buffering capacity. Used in Li-ion battery anodes, it exhibited a specific discharge capacity of 514.4 mAh/g after 1000 cycles at a current density of 0.5 A/g with durable long cycling performance. In addition, the addition of high iron-sol induced the formation of porous core–shell nanoparticles and performed excellent electromagnetic wave absorption ability. The ceramic nanoparticles with carbon content of about 30% had the lowest reflection loss in the X-band of −55.5 dB, and the effective absorption range was 8.48–12.4 GHz, which basically covered the entire X-band. This strategy enriches the preparation and application of multifunctional composite ceramic nanoparticles.