*Article* **Transformation of SnS Nanocompisites to Sn and S Nanoparticles during Lithiation**

**Haokun Deng 1,\*, Thapanee Sarakonsri 2, Tao Huang 3, Aishui Yu <sup>3</sup> and Katerina Aifantis <sup>4</sup>**


**Abstract:** SnS nanomaterials have a high initial capacity of 1000 mAh g<sup>−</sup>1; however, this cannot be retained throughout electrochemical cycling. The present study provides insight into this capacity decay by examining the effect that Li intercalation has on SnS "nanoflowers" attached on carbon substrates' such as artificial graphite. Scanning and transmission electron microscopy reveal that lithiation of such materials disrupts their initial morphology and produces free-standing Sn and SnS nanoparticles that dissolve in the electrolyte and disperse uniformly over the entire electrode surface. As a result, the SnS is rendered inactive after initial cycling and contributes to the formation of the solid electrolyte interface layer, resulting in continuous capacity decay during long term cycling. This is the first study that illustrates the morphological effects that the conversion mechanism has on SnS anodes. In order to fully utilize SnS materials, it is necessary to isolate them from the electrolyte by fully encapsulating them in a matrix.

**Keywords:** anode; tin sulfide; lithium ion battery; conversion reaction; nanoflower

**Citation:** Deng, H.; Sarakonsri, T.; Huang, T.; Yu, A.; Aifantis, K. Transformation of SnS Nanocompisites to Sn and S Nanoparticles during Lithiation. *Crystals* **2021**, *11*, 145. https:// doi.org/10.3390/cryst11020145

Received: 27 December 2020 Accepted: 23 January 2021 Published: 29 January 2021

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