SnO2 nanorods encapsulated within a 3D interconnected graphene network architecture as high-performance lithium-ion battery anodes

Abstract

SnO₂ nanorods (NRs) have been demonstrated as one of the potential candidates for high-performance lithium-ion battery anodes due to their unique structural features, high theoretical capacity, natural abundance and low cost of fabrication. However, they still suffer from the problem that their direct exposure to the electrolyte leads to the instability of the SEI layer, causing low coulombic efficiency, high ionic resistance and low electronic conductivity. In this study, SnO₂ NRs were synthesized by a hydrothermal method, and then spatially confined within graphene sheets by a facile freeze-drying process. The as-fabricated architecture exhibits a full encapsulation arrangement with graphene sheets interlaced into an interconnected macroporous network, serving not only as a robust framework with accessible space for the electrolyte but also a physical barrier layer to prevent the SnO₂ NRs from direct exposure to the electrolyte. Moreover, the SnO₂ NRs can function as pillars to prevent the graphene sheets from restacking while preserving the highly robust structure and efficient electron and ion transport channels. Benefiting from the admirable synergistic effect between SnO₂ NRs and graphene, the assembled electrode shows excellent cycle performance (1179.2 mA h g⁻¹ after 400 cycles at 1.0 A g⁻¹) and rate capabilities (624.2 mA h g⁻¹ at 8.0 A g⁻¹; 458.4 mA h g⁻¹ at 16.0 A g⁻¹).