Amino-terminated hyperbranched polyamide regulating Cu2S twin-daffodil with enhanced sodium-storage performance

Abstract

Electrochemical conversion reaction offers plenty of material options for high-capacity Na-ion battery anodes; however, the poor long-term cyclability is seriously blocking their practical utilization. In the present study, a new amino-terminated hyperbranched polyamide (AHP) is employed to construct a unique twin-daffodil shaped Cu2S anode for Na-ion batteries. First as a reaction template, the AHP regulates the formation of a special hierarchical twin-daffodil structure for Cu2S. Secondly and more importantly, the AHP acts as an additive remaining in the Cu2S, offering an elastic framework to prevent the nanograin aggregation and effectively enhanced the cycling stability. This Cu2S twin-daffodil shows a remarkable capacity of 370 mAh g−1 at 100 mA g−1 and a superior cyclability without obvious fading within 1000 cycles. Further investigation demonstrates fast solid-state Na+ diffusion kinetics in such Cu2S twin-daffodil, which leads to an outstanding rate capability of 170 mAh g−1 at 20 A g−1. This research not only provides a potential electrode for Na-ion batteries, but also introduces a new method to improve the performance of conversion materials for Na-ion batteries.