Interstratification-assembled 2D black phosphorene and V(2)CT(x)MXene as superior anodes for boosting potassium-ion storage

摘要

Although potassium-ion batteries have been widely studied because of their low cost and high theoretical capacity, the origin of the poor potassium-ion storage kinetics and low structural stability still remains elusive mainly due to the large size of K+(0.138 nm). Herein, we report an interstratification-assembly strategyviavan der Waals interactions to design a novel BPE@V(2)CT(x)hybrid anode, wherein black phosphorene (BPE) and V(2)CT(x)MXene are derived from their individual 2D nanosheets. The coupled BPE@V(2)CT(x)hybrid anode with a 2D stacked interstratification structure and large specific surface area could efficiently take advantage of BPE and V(2)CT(x)nanosheets and create more active sites. This interstratification hybrid electrode not only provides an enlarged interlayer spacing and a three-dimensional interconnected conductive network to accelerate the K(+)transport rates, but also has good tolerance to volume changes caused by phase transformations during the fast potassiation/depotassiation process. DFT calculations further confirm that potassium affinities and diffusion kinetics are significantly enhanced in the BPE@V(2)CT(x)hybrid anode, particularly in BPE@V2CF2. As a result, the hybrid anode possesses a remarkable synergetic effect and achieves a high reversible capacity of 593.6 mA h g(-1)at 0.1 A g(-1)and excellent cycling stability of 485/261 mA h g(-1)with 91/86% capacity retention after 3000 cycles at 0.2/2.0 A g(-1). This work opens a new way for the application of self-assembled hybrid electrodes in energy storage, electrocatalysis and sensors.