Quantum dot heterostructures on N-doped graphene with accelerated diffusion kinetics for stable lithium-ion storage

The high energy density and low self-discharge rate of lithium-ion batteries make them promising for large-scale energy storage. However, the practical development of such electrochemical energy storage systems relies heavily on the development of anode materials with high multiplier capacity and stable cycle life. Here, a simple and efficient one-step hydrothermal method is used to obtain stannide heterostructures, which are loaded on N-doped graphene (SnS₂/SnO₂@NG) that promotes Li⁺ diffusion for fast charge transfer. It is demonstrated that the built-in electric field generated by the electron transfer from electron-rich SnS₂ to SnO₂ in the stannide heterojunction collectively provides abundant cation adsorption sites, accelerating the migration of Li⁺ thus improving the electrochemical reaction kinetics. Besides, the SnS₂/SnO₂ nanoparticles have high structural stability, and the heterojunction compressive stresses obtained from density functional theory (DFT) calculations can significantly limit the structural damage. When applied as anodes in Li⁺ batteries with 300 cycles at 0.5 A/g, we achieved a high reversible capacity of 892.73 mAh/g. The rational design of low-cost batteries for energy storage and conversion can benefit from the quantitative design of fast and persistent charge transfer in a stannide heterostructure.