As same classification of tin-based chalcogenides system, all of the SnX (X=S/Se/Te) should possess similar structural characteristics by our conventional view. However, the experimental SnS&SnSe possess orthorhombic-phase structure while SnTe refers to other cubic-phase. How to explain above structural-transition and quantify the impact on their electrochemical behaviors are remained challenge. Herein, such phenomena are investigated by both experimental-tools and theoretical-calculations. The results show that the integration of S/Se into Sn would trigger serious lattice-distortion, bonding-broken and thus phase-transition from cubic to orthorhombic SnS&SnSe due to their large difference on atomic-radius and electronegativity. While fusing Te atom into Sn to form the SnTe enables a well maintained cubic-structure phase like Sn matrix owing to their similar physicochemical properties. Benefitted from above structure characteristics, the SnTe enables to keep Sn-like metallic conductivity (3.31×10 3 S m −1 ), larger tap-density (6.48 g cm −3 ) and better reaction-kinetic, thus delivering better cyclability (698mAh g −1 after 200cycles) and rate performance (236mAh g −1 at 10A g −1 ) for LIBs. Besides, the SnTe even exhibits higher pseudo-capacitance contribution (94%) and thereby, the assembled AC//SnTe Li-ion capacitor enables high energy & power density (114 Wh kg −1 , 7000 W kg −1 ) and superior cyclability (92.7%-retention after 8000 cycles) for lithium-storage. The above understanding of structure-transition and electrochemical-evolution may open avenue for material design towards advanced energy storage. The structural transition from orthorhombic SnS & SnSe to cubic SnTe can be greatly revealed with theoretical and fundamental atomic analysis. Cubic SnTe enables a higher conductivity, larger tap density and better Li-diffusivity, thus delivering better cyclability (698 mAh g ‒1 after 200 cycles) and rate performance (236 mAh/g at 10 A/g) for LIBs. Besides, owing its high pseudo-capacitance contribution, the fabricated AC//SnTe capacitor achieves large energy density (114 Wh/kg), high power density (7000 W/kg) and superior cyclability (92.7% retention after 8000 cycles) for advanced lithium storage. ● The structural transition relationship between orthorhombic SnS & SnSe and cubic SnTe is greatly revealed. ● The structural oriented electrochemical behavior evolution between SnS & SnSe and SnTe can be quantified by solid experiments. ● The SnTe anode with large capacity, superior cyclability and rate capability can be served as alternative anode for advanced Li-ion batteries and capacitor.
Liu et al. (Sun,) studied this question.