Abstract

In two-dimensional materials, black phosphorus has shown excellent performance as electrode materials for lithium- and sodium-ion batteries, due to its thermodynamic stability, layered anisotropic structure, and electrical conductivity. Recently, high capacity anodes based on black phosphorus as an active component for potassium-ion batteries (PIBs) have also been reported. However, in-depth studies are required to clarify the adsorption and diffusion of K ions on black phosphorus and the K–P reaction mechanism. In this work, the surface adsorption, bulk diffusion, and K–P binary phase formation were firstly investigated in detail using first-principle calculations. We found that compared with Li and Na, K has the lowest diffusion energy barrier in the bulk phase (0.182 eV for zigzag type and 2.013 eV for armchair type). Black phosphorus structure irreversibly collapses when the K ion concentration is up to 0.625, and no K₃P phase is formed through the electrochemical profiles obtained by calculation of the binary phase alloy structures. Furthermore, the maximum capacitance of black phosphorous for PIBs is calculated to be 864.8 mAh.g⁻¹. This work will help in understanding the mechanism and further improving the performance of K-ion batteries.

Graphic Abstract

摘要

在二维材料中，黑磷由于其热力学稳定性，分层的各向异性结构和导电性，已显示出优异的性能，可作为锂离子和钠离子电池的电极材料。近来，也已经报道了基于黑磷的高容量阳极，作为钾离子电池（PIB）的活性成分。但是，需要进行深入研究以阐明钾离子在黑磷上的吸附和扩散以及钾磷反应的机理。在这项工作中，首先使用第一性原理详细研究了表面吸附，整体扩散和K-P二元相的形成。我们发现，与Li和Na相比，K在体相中的扩散能垒最低（锯齿形为0.182 eV，扶手椅形为2.013 eV）。通过计算二元相合金结构获得的电化学曲线形成₃ P相。此外，PIB的黑磷的最大电容经计算为864.8 mAh.g ^-1。这项工作将有助于理解K离子电池的机理并进一步提高其性能。

图形摘要