rGO/SnS2/TiO2 heterostructured composite with dual-confinement for enhanced lithium-ion storage

Next-generation lithium ion batteries (LIBs) require new electrode materials with high energy/power density, good safety and long cycle life. SnS2 is a promising anode candidate due to its high theoretical capacity; however, it still suffers from low electronic/ionic conductivity and large volume expansion during lithiation, which hinder its practical application. Herein, we report the construction of a two-dimensional (2D) heterojunction composite electrode comprised of ultrafine SnS2 and TiO2 nanoparticles deposited on reduced graphene oxide (rGO) nanosheets. This composite exhibits superior lithium-ion storage capability in terms of high capacity, superior rate property and excellent cycling stability. The performance improvement is primarily due to the synergic coupling of various components in the composite: (1) rGO serves as a fast channel for rapid electron transport and an ideal host for the mass loading of SnO2 and TiO2; (2) ultrafine SnS2 nanoparticles with abundant defects manifest high reactivity for lithiation; and (3) TiO2 forms intimate contact with SnS2, boosting Li+/e(-) transfer at the interfaces. TiO2 also effectively pins the SnS2 particles, which prevents their migration, aggregation and detachment from the rGO substrate, ensuring the structural integrity and cycling stability of the composite electrode. The dual-confinement strategy using N-Sn bonds and TiO2 decoration together with heterostructure construction presented herein can pave the way for the development of more advanced composite materials for high-performance alkali-metal ion batteries.