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.