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.

Automated summary

The study showed that the composite of SnO2 with nanoporous carbon (Co-Sn@NC) synthesized using ZIF-67 exhibited enhanced structural stability and improved rate capacity for tin-based compounds. The research revealed that among the composites prepared with three different molar ratios of 2-methylimdazole, the carbon-based Co-Sn alloy with the highest amount of N-doped organic linker delivered the highest reversible capacity.