p–n heterogeneous Sb2S3/SnO2 quantum dot anchored reduced graphene oxide nanosheets for high-performance lithium-ion batteries

Abstract

Antimony sulfide (Sb₂S₃) has a high theoretical specific capacity due to its two reaction mechanisms of conversion and alloying during the Li⁺-(de)intercalation process, thus becoming a promising lithium-ion battery (LIB) anode material. However, its poor inherent conductivity and large volume expansion during repeated Li⁺-(de)intercalation processes greatly hinder the in-depth development of Sb₂S₃ based LIB anode materials. Herein, an Sb₂S₃/SnO₂@rGO composite was prepared by using an interface engineering technique involving metal-containing ionic liquid precursors, in which Sb₂S₃/SnO₂ quantum dots (QDs) as p–n heterojunctions are uniformly anchored on the surface of reduced graphene oxide (rGO). The p–n heterogeneous interface between Sb₂S₃ and SnO₂ QDs induces an internal electric field, promoting the electronic/ion transport during electrochemical reactions, and the QD-sized Sb₂S₃/SnO₂ heterostructure with a larger surface area provides more active sites for Li⁺-(de)intercalation reactions. In addition, the rGO matrix acts as a buffer to prevent the aggregation of active Sb₂S₃ and SnO₂ QDs, alleviate the volume expansion, and enhance the conductivity of the composite during repeated cycles. These advantages endow the designed Sb₂S₃/SnO₂@rGO electrode with excellent reaction kinetics and good long cycling stability. As an anode material of LIBs, it can still provide a reversible specific capacity of 474 mA h g⁻¹ after 2000 cycles at a high current density of 3.0 A g⁻¹, which is superior to those of most of the previously reported Sb₂S₃-based carbon materials. The p–n heterostructure construction strategy of nano-metal sulfide/metal oxides in this work can provide inspiration for the design and synthesis of other advanced energy storage materials.