dc.description.abstract | Lithium-ion batteries (LIBs) are the most widely used rechargeable batteries for powering electronic devices such as electric vehicles (EV), laptop computers and cellular phones due to their high energy density. We proposed to use ternary Sn-Sb-S metal sulfide as the active materials for LIBs. Specifically, Sn(1)-Sb(2)-S(4) and Sn(3)-Sb(2)-S(6) were first prepared and tested as anode. It is expected that the stepwise lithium insertion mechanism can alleviate volume changes and improve the mechanical stability of the electrode.
In this study, the Sn(1)-Sb(2)-S(4) and the Sn(3)-Sb(2)-S(6) powders are synthesized using solvothermal and physical mixture method. The as-prepared powders and annealed (500 oC) ones were tested. Noted that the as-prepared samples exhibited mixtures of SnS and Sb2S3. Depending on the preparation conditions, annealed samples show a major phase of SnSb2S4 and Sn3Sb2S6. Compare the Sn(1)-Sb(2)-S(4) and the Sn(3)-Sb(2)-S(6) with Sb2S3 and SnS, annealed Sn(3)-Sb(2)-S(6) powder provides the highest capacity of 829 mAh/g. However, anneaned Sn(1)-Sb(2)-S(4) powder has the best cycle stability with the reversible capacity of 164 mAh/g after 150 cycles at a constant current of 300 mA/g, corresponding to 28 % retention.
In a parallel experiment, binder and electrolyte were changed to improve the capacity and retention. Here, the binder, PVdF was replaced by polyimide DB100. The electrolyte was switched from commercial electrolyte (1 M LiPF6 in EC/DEC) to 1 M LiPF6 in FEC/DEC. The capacities of ternary metal sulfide (Sn-Sb-S) were significantly enhanced, even better than that of the Sb2S3 and SnS binary metal sulfide. At a constant current of 250 mA/g, Sn(3)-Sb(2)-S(6) powder exhibits a reversible capacity of 963 mAh/g after 50 cycles with the retention of 92 %.
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