Tetranuclear Organotin Sulfide Cage [(RSn^IV)₄(μ-S)₆] as an Anode Material for a Lithium-Ion Battery (LIB)

The reversible redox behavior of electroactive organic groups in organometallic compounds makes them a potential candidate for preparing electrode materials for the emerging generation of high-performance lithium-ion battery (LIB) applications. Meanwhile, due to their nontoxic nature and cost-effective manufacturing, the huge potential of various tin–sulfur-based materials has been explored for LIB applications. On account of the superior advantage of organic- and Sn–S-based electrodes, a tetranuclear organotin sulfide cage, [(RSn^IV)₄(μ-S)₆], 2, was designed from a newly synthesized monoorgano tin precursor RSnCl₃, 1, where R = (2,4-dimethylpentylidene)­hydrazinylpyridine. The molecular structures of these compounds are characterized by single-crystal X-ray diffraction (SCXRD) and various other spectroscopic techniques. In this work, compound 2 was exclusively examined as an anode material for LIBs. The designed electrode has shown interesting rate-dependent specific capacities. A specific discharge capacity of 135.6 mAh g^–1 was observed at a current density of 75 mA g^–1 with 75% capacity retention after 100 cycles. Two different types of rate-dependent lithiation mechanisms have been identified. It was found that at a higher rate (0.4 C), the molecule can accommodate 8 Li⁺ ions showing a specific capacity of 126 mAh g^–1, whereas at a slower rate (C/30), the molecule can accommodate 16 Li⁺ ions delivering a specific capacity of 232 mAh g^–1.