SnS−SnO2 Heterostructures Anchored on GO as a High-Performance Anode for Sodium Ion Battery
Graphical This work aims to improve conductivity and cycle stability of bare SnO 2 through constructing special p-n heterostructures and graphene oxide (GO) modification to promote charge transfer and electrochemical reversibility, protect the intrinsic materials and alleviate volume expansion. Further, the band structure and charge state density of SnS−SnO 2 @GO were simulated by first principles, whose accuracy was verified in the practical experiments subsequently. SnO 2 is a theoretically excellent transformed anode material with high theoretical capacity for SIBs. However, SnO 2 faces serious volume effect and high resistance, which greatly damages its electrochemical performance. Given that, the SnS−SnO 2 heterostructures is constructed with special internal electric field, which is beneficial to promote the transfer ability of sodium ions. Besides, the graphene oxide (GO) modification is carried out to isolate the intrinsic materials from direct contact with electrolyte, and alleviate volume expansion of the anode, ultimately promote the electrochemical performance. Furthermore, the structure and the conductivity characteristics of SnS, SnO 2 , SnS−SnO 2 and SnS−SnO 2 @ GO are simulated respectively by first principles and are compared with the correspondence experiment results to verify the accuracy of established models. Owing to the special p-n junction in SnS−SnO 2 @GO heterostructures, the resistance of SnS−SnO 2 @GO can be reduced to 36.23 Ω, much lower than that of SnO 2 (Rct=341.9 Ω). Notably, the combination of GO has effectively alleviated the volume expansion of SnS−SnO 2 @GO electrodes, and present excellent capacity higher than 384.7 mAh g −1 after 100 cycles. Thus, the efficient synthesis of SnS−SnO 2 @GO heterostructure electrodes with excellent performance for sodium storage is expected to provide valuable direction for SIBs anode materials.
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