p-n heterogeneous Sb 2 S 3 /SnO 2 quantum dot anchored reduced graphene oxide nanosheets for high-performance lithium-ion batteries.

Antimony sulfide (Sb 2 S 3 ) 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 Sb 2 S 3 based LIB anode materials. Herein, an Sb 2 S 3 /SnO 2 @rGO composite was prepared by using an interface engineering technique involving metal-containing ionic liquid precursors, in which Sb 2 S 3 /SnO 2 quantum dots (QDs) as p-n heterojunctions are uniformly anchored on the surface of reduced graphene oxide (rGO). The p-n heterogeneous interface between Sb 2 S 3 and SnO 2 QDs induces an internal electric field, promoting the electronic/ion transport during electrochemical reactions, and the QD-sized Sb 2 S 3 /SnO 2 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 Sb 2 S 3 and SnO 2 QDs, alleviate the volume expansion, and enhance the conductivity of the composite during repeated cycles. These advantages endow the designed Sb 2 S 3 /SnO 2 @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 Sb 2 S 3 -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.