ZIF 67 derived Co–Sn composites with N-doped nanoporous carbon as anode material for Li-ion batteries

Owing to low cost and high theoretical capacity of 994 mAh g⁻¹, tin has received much attention for its applications relevant to energy storage devices including lithium-ion batteries. However, the structural instability of tin-based compounds becomes prominent during lithium-ion insertion/extraction mechanism and this decreases its cyclic life and rate capacity. Mitigating the structural instability and corresponding improvement in rate capacity require novel strategies, and herein composite of SnO₂ with nanoporous carbon was synthesized using ZIF-67 which creates a framework composed of Co–Sn alloy and Sn–C network that is responsible for enhanced structural stability. The electrochemical behavior of the Co–Sn@NC composite with three different molar ratios of 2-methylimdazole was investigated using cyclic voltammetry (CV), and a multi-channel battery analyzer. The later analysis revealed that after 50 cycles at a current density of 0.1 A g⁻¹, Co–Sn alloy with carbon matrix having the maximum amount of N-doped organic linker delivered the highest reversible capacity of 601 mAh g⁻¹. This can be attributed to well-dispersed nano Co–Sn alloy embedded within the porous structure of carbon matrix, thus providing an effective cushion for releasing volumetric strain that develops within the structure.