Atomically dispersed Sn incorporated into carbon matrix for stable electrochemical lithium storage

Although possessing a high specific capacity, the practical implementation of SnO₂ nanoparticles as a promising anode for lithium-ion batteries (LIBs) is hampered by their poor cyclability. This work demonstrates that incorporating single atomic Sn (SASn) species into a carbon matrix can address this issue effectively. The SASn/C composite was synthesized via polymerization of formaldehyde and 3-aminophenol in the presence of Tin(II) chloride, followed by pyrolysis. The SASn atoms were homogeneously dispersed in the carbon matrix. Each Sn atom coordinated with two O and two C atoms, forming the Sn-O-C and Sn-C bonds, providing channels for fast electron/ion transfer and boosting electrochemical kinetics. The SASn/C anode exhibited unique lithium storage behaviors, enhanced lithium storage capability, and excellent cyclic stability with a capacity fading rate of 0.0031% per cycle at 1000 mA g⁻¹ after 7000 cycles. Density functional theory calculations reveal that one SASn atom can adsorb three Li⁺ ions at the fully discharged state during the discharging process. Subsequently, the Li⁺ ions are directly desorbed from the SASn atom, which is different from the traditional multi-step de-alloying process. This facile strategy represents a significant advancement in developing high-performance Sn-based anode materials for LIBs.