ZnSe nanoparticles combined with uniform 3D interconnected MWCNTs conductive network as high-rate and freeze-resistant anode materials for sodium-ion batteries

ZnSe as anode material for sodium ion batteries (SIBs) has received great attention due to its high theoretical specific capacity, environmental friendliness and low price. However, its electrochemical performance is hindered by large volume variation and poor electrical conductivity. In this work, we reported a one-step hydro thermal strategy of ZnSe/MWCNTs (Multi-walled Carbon Nanotubes) to form ZnSe nanoparticles combined with uniform 3D interconnected MWCNTs conductive network to synergistically boost sodium-ion storage process. Especially, the uniform 3D interconnected MWCNTs conductive network plays a vital role of enhanced elect racial conductivity, ionic diffusivity and structural stability so that it can achieve excellent electrochemical performance at both room and low temperature. Also, pseudocapacitance in redox processes is dominated leading to superior rate performance. When the optimal ZnSe/MWCNTs (denoted by ZnSe-40) are applied at room temperature, it delivers 398.8 mA h g(-1) at 0.1 A g(-1) after 50 cycles and superior rate performance (279.4 mA h g(-1) at 10 A g(-1)). Its capacity retention can still be 93% at 4 A g(-1) after 300 cycles. What is pleasantly surprised, even at low temperature (-10 degrees C), ZnSe-40 shows good long-term cycling stability of 246.7 mA h g(-1) at 1 A g(-1) after 600 cycles and 180.5 mA h g(-1) at 5 A g(-1). The reaction mechanism in sodiation/desodiation process is explored by discussing the change of intermediate products through ex-situ characterization methods.

Automated summary

In this study, ZnSe/MWCNTs were prepared as an anode material for sodium ion batteries, exhibiting excellent electrochemical performance and superior rate capability. The uniform 3D interconnected MWCNTs conductive network played a crucial role in enhancing electron conductivity, ionic diffusivity, and structural stability, leading to outstanding performance both at room temperature and low temperature.