Intercalating Elemental Se₈ Rings and Cs⁺ Ions by Layered Selenidostannate: A Semiconductive Material for High-Energy Li-Ion Battery Anodes

Tin chalcogenide has recently received a great deal of consideration due to its versatile structures and interesting electrical properties. Herein, we report an unprecedented crystalline Sn–Se compound, {Se8Cs3@[Sn3Se13]}n Cs3Sn3Se21, featuring elemental Se8 rings and Cs+ ions intercalated between the [Sn3Se13]n3n- layers. Dark single crystals of Cs3Sn3Se21 show unusual metallic lust, a narrow band gap of 1.31 eV, and an electrical conductivity of 1.24 × 10–5 S/cm at ambient temperature. Under visible-light illumination, Cs3Sn3Se21 generates a high photocurrent density of 1.2 μA cm–2 at a biased low potential of 0.8 V. More importantly, Cs3Sn3Se21 can be used for the Li-ion battery anode material, showing excellent specific capacity of 490 mAh g–1 at a current density of 50 mA g–1. Furthermore, the material demonstrated high stability; even after cycling at 2000 mA g–1, the capacity can be restored to 488 mAh g–1 once the current density is recovered, confirming the superior rate performance.