Nickel-cobalt selenide@N-doped carbon towards high-performance anode materials for sodium-ion batteries

Sodium-ion battery is an intriguing candidate in the post-lithium era due to the earth-abundance of sodium. Transition metal selenides, with high conductivity and theoretical capacity, have been widely used in sodium-ion batteries. However, their structures are easily crushed when assembled as the anode, resulting in rapid capacity decay and poor rate performance, limiting its commercialization. In the present work, nickel-cobalt selenide coated by nitrogen-doped carbon is prepared to activate multi-electron redox reactions. The composite exhibits excellent rate capacity (457 mAh g(-1) at 0.1 A g(-1) and 296 mAh g(-1) when the current density is increased to 5 A g(-1)) and cycling stability (300 mAh g(-1) after 1800 cycles at 2 A g(-1)). When assembled into a sodium ion battery, a high and stable specific capacity is also realized. This work illustrates the effectiveness of in-situ carbon coating as well as the potential advantages of selenide-carbon composite as an anode material for sodium-ion batteries.

Automated summary

In this study, nickel-cobalt selenide coated by nitrogen-doped carbon is prepared to improve its crush resistance, leading to high rate capacity and cycling stability in sodium-ion batteries.