FeNi-quantom-dots induced stable interfaces of high loading FeNCN electrode for enhanced sodium storage performance

[Display omitted] •The interfacial structure of the FeNCN electrode was improved by FeNi-quantum-dot.•The reaction kinetics of FeNCN was greatly promoted by FeNi-quantum-dots.•This modified interface could stabilize the Na+ storage of FeNCN electrode.•The FeNCN electrode presents high rate performance with this modified interface. As a highly reactive anode material with great potential in sodium-ion battery, iron carbodiimide (FeNCN) often suffers from shuttle effect with performance degradation. Therefore, the interface structure of FeNCN is in urgent need for improvement to solve the above problem. In this article, an FeNi-quantum-dot/carbon tube modified separator was used to regulate the interface of FeNCN with high loading (3 mg cm−2). By using this strategy, the FeNCN electrode could present high Na+ storage performance of 410.4 mAh/g after 100 cycles at 2 A/g with capacity retention rate of 99.9 % per cycle. Further analysis showed that FeNi quantum dots could inhibit the shuttle effect of Na2NCN with stable charge/discharge process. They could also facilitate the formation reaction of iron carbodiimide, realizing fast electrochemical reaction kinetics in high loading FeNCN electrode. Consequently, this work exhibits a simple and effective strategy to enhance the Na+ storage performance of iron carbodiimide, which could also inspire insights to other transitional metal-based electrode material systems.