Necklace-like NiCo2O4@carbon composite nanofibers derived from metal-organic framework compounds for high-rate lithium storage

In this study, a necklace-like NiCo2O4@carbon composite nanofiber (NCO@CNF) anode composed of a metal-organic framework, featuring low volume expansion and high rate properties, was prepared as an anode for lithium-ion batteries. By tuning the ratio of the ZIF-67 precursor and growth time, unique necklace-like NCO@CNFs were synthesized for the first time. The novel necklace-like NCO@CNFs presented an interconnected architecture with a large specific surface area (194.2 m(2) g(-1)), robust pore structures and superior mechanical strength. Benefiting from the abovementioned excellent physical properties, the issue of volume expansion derived from Li+ insertion/extraction during cycling was effectively mitigated by improved ionic transportation kinetics when the prepared NCO@CNFs were applied as an anode in a lithium-ion battery. Through a series of electrochemical measurements, the NCO@CNF electrode exhibited a high specific capacity of 1953 mA h g(-1) at the current density of 0.3 A g(-1), prolonged cycling stability with a reversible capacity of 1388 mA h g(-1) after 500 cycles and good rate capability with a reversible capacity of 652 mA h g(-1) at a high current density of 2 A g(-1). Moreover, its excellent stability was revealed by the sustained integrity of its necklace structure, similar to that of the fresh electrode, without significant volume expansion or pulverization even after 500 cycles.

Automated summary

A necklace-like NiCo2O4@carbon composite nanofiber (NCO@CNF) anode with low volume expansion and high rate properties was synthesized for lithium-ion batteries by tuning the ratio of the precursor and growth time. The NCO@CNFs exhibited interconnected architecture, large specific surface area, robust pore structures, and superior mechanical strength, effectively mitigating volume expansion issue during cycling. This novel electrode showed high specific capacity, prolonged cycling stability, and good rate capability, indicating excellent performance and stability in lithium-ion battery applications.