Recently, flexible electrodes with biaxial/omnidirectional stretchability have attracted significant attention. However, most existing pliable electrode materials can be only stretched in one direction. In this work, an unexpected isotropic van der Waals (vdW) heterostructure is proposed, based on the assembly of two-dimensional crystals of anisotropic black phosphorene (BP) and transition metal carbide (TiC₂). Using vdW-corrected density functional theory calculations, the BP/TiC₂ vdW heterostructure was predicted to have excellent structural and mechanical stability, superior electrical conductivity, omnidirectional flexibility, and a high Li storage capacity. We have unraveled the physical origin of the excellent stability, as well as the Li adsorption preferences of the lithiated heterostructure, based on a three-step analysis of the stability of the Li-adsorption processes. In addition, the BP/TiC₂ vdW heterostructure can also be applied as the anode material for flexible Na-ion batteries because of its high Na storage capacity and strong Na binding. However, compared with Na adsorption, the capacity is higher, and the adsorption energy is more negative for Li adsorption. Our findings provide valuable insights into the exploration of a rich variety of vdW heterostructures for next-generation flexible energy storage devices.

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近来，具有双轴/全向可拉伸性的柔性电极引起了极大的关注。但是，大多数现有的柔韧性电极材料只能在一个方向上拉伸。在这项工作中，基于各向异性的黑色磷光体（BP）和过渡金属碳化物（TiC ₂）的二维晶体组装，提出了一种出乎意料的各向同性范德华（vdW）异质结构。使用经vdW校正的密度泛函理论计算，BP / TiC ₂预计vdW异质结构具有出色的结构和机械稳定性，优异的电导率，全向柔性以及高的Li储存能力。我们基于对Li吸附过程稳定性的三步分析，揭示了优异稳定性的物理来源以及锂化异质结构的Li吸附偏好。此外，BP / TiC ₂vdW异质结构也可以用作柔性Na离子电池的负极材料，因为其高的Na储存能力和强大的Na结合力。但是，与Na吸附相比，其容量更高，而Li的吸附能量则更大。我们的发现为探索下一代柔性储能设备的多种vdW异质结构提供了宝贵的见识。

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