Standout electrochemical performance of SnO2 and Sn/SnO2 nanoparticles embedded in a KOH-activated carbonized porous aromatic framework (PAF-1) matrix as the anode for lithium-ion batteries

Abstract

Attributed to their high specific capacity and safe working potential versus Li/Li⁺ as compared to commercial graphite anodes, tin and tin oxide have received widespread attention as promising anode materials for Li-ion batteries, whereas they also suffer from some drawbacks, such as large volume expansion and poor electrical conductivity during the lithiation/delithiation process. To address these issues, a series of composites with ultrasmall Sn and SnO₂ nanoparticles (6–15 nm) embedded in a KOH-activated carbonized porous aromatic framework (PAF-1) matrix as anode materials were prepared by adjusting the Sn²⁺ content and carbonization temperature. Attributed to its high microporosity and electrical conductivity, the KOH-activated carbonized PAF-1 is a potential host matrix to cogently solve the problems of pulverization, metal aggregation and loss of electrical contact with the electrode over repeated cycling. The synergy between SnO_x and the carbon matrix is manifested by the outstanding capacity and stability of the material, which owes its standout features to the SnO_x nanoparticles located inside the micropores of the carbon matrix. Of all the materials, SnO_x@K-PAF-1-750-25 prepared by optimizing the contents and preparation conditions showed excellent stability and cycling performance, retaining a capacity of 608 mA h g⁻¹ over 400 charge/discharge cycles even at a high current density of 400 mA g⁻¹.