*3.1. Microstructure Prior Electrochemical Cycling*

In Figure 1 the FESEM images show that for all nanocomposites fabricated, the SnS particles had an open (flower-like) structure and were attached on the carbon powder (AG or MCMB) surfaces.

To determine the average particle size, 50 areas were imaged for each sample. In addition, EDS was also performed in order to determine the at% of the Sn and S. Table 1 presents the averaged semiquantitative EDS analysis, which indicates that the Sn and S at% was higher when MCMB was used as the precursor. The 10SnS/AG sample contained the lowest at% of active SnS material, as well as the smallest average particle size.

**Figure 1.** The field emission scanning electron microscope (FESEM) images of the new as prepared samples, before lithiation: (**a**) the 10SnS/artificial graphite (AG) composite; (**b**) the 10SnS/multicarbon– microbeats (MCMB) composite; (**c**) the 20SnS/AG composite; (**d**) the 20SnS/MCMB composite.

**Table 1.** FESEM–electron dispersive spectroscopy (EDS) analysis conducted before cycling to determine the content and particle size of Sn and S.


Performing TEM on the as prepared powders, as seen in Figure 2, indicated that the SnS particles consisted of multiple nanofiber/nanorod-like petals. Selected-area electron diffraction (SAED) conducted on the nanofibers indicated the presence of an SnS phase (JCPDS card #39-354 for SnS).

The formation of the SnS alloy was further verified by X-ray diffraction (XRD). In Figure 3, it is illustrated that all as prepared samples contained only C (JCPDS card #41-1487 for C) and SnS, while pure Sn or S phases were not present, which is consistent with the SAED results of Figure 2. Furthermore, using the Panalytical X' Pert Plus software, the crystal size within the SnS flower-like particles before cycling was found to be ~10 nm.

**Figure 2.** Transmission electron microscope (TEM) image and selected-area electron diffraction (SAED) pattern of the SnS structure of the as prepared 10SnS/AG sample. In all prepared nanocomposites, the SnS particles had this microstructure.

**Figure 3.** X-ray diffraction (XRD) of the SnS/carbon composites before cycling. **Green**: 20SnS/AG, **purple**: 20SnS/AG, **red**: 20SnS/MCMB, **black**: 10SnS/MCMB.
