Multifunctional core–shell CaSnO3@N-doped carbon coaxial nanocables with excellent lithium storage performance and efficient microwave absorption†

It is highly desirable but challenging to design multi-functional materials for energy storage and electromagnetic (EM) wave absorption. Herein, core–shell CaSnO₃@N-doped carbon (CSO@NCNF) coaxial nanocables with one-dimensional (1D) architecture were synthesized by employing the electrospinning method combined with in situ polymerization and heat treatment. In the resulting structure, the CaSnO₃ nanofiber (CSONF) core with an average diameter of 52.5 nm is confined in the high electronic conductivity of the N-doped carbon sheaths with a thickness ranging from 27.3 to 67.2 nm. The lithium storage performance of the CSO@NCNF nanocable electrode is much higher than that of the CSONF electrode; this is owing to the (i) large number of void spaces and active sites generated by the structure of the 1D core–shell nanocables, (ii) fast transport network constructed by carbon sheaths prominently enhancing the transport of both electrons and lithium ions, and (iii) structural stability achieved through the buffering mechanism created by CaSnO₃@NCNF coaxial construction. However, its ingenious structural design, multiple heterogeneous interfaces and multi-component strategy give rise to a synergistic mechanism of impedance matching, conductive loss, polarization loss and multiple reflection/scattering. The coaxial nanocables display good microwave absorption (MA) properties, featuring a reflection loss (RL) value of −47.0 dB at 8.2 GHz and 2.5 mm as well as an effective absorption bandwidth (EAB) of 4.7 GHz at 1.4 mm. This unique structural design is believed to provide a reference for the preparation of multi-functional materials.