Fig. 2

TEM characterization of shell and core components of the LSMCS electrode. a, b TEM images of the graphene shell extracted from the electrode revealing graphitic layered structure; inset in a is an electron diffraction confirming the crystallinity of the graphene shell. c, d TEM images of the spongy carbon core comprising interconnected carbon nanoparticles and crumpled graphitic nanosheets. e, f High magnification TEM images of carbon nanoparticles, which are composed of iron carbide encapsulated in thick graphitic layers. Red-dotted rectangles in a, c, and e are marked areas corresponding to their high magnification images shown in b, d, and f, respectively. White scale bar in a is 100 nm, in the inset of a 5 1/nm, in b 10 nm, in c 100 nm, in d 10 nm, in e 50 nm, and in f 5 nm.