Few-Layer Antimonene: Anisotropic Expansion and Reversible Crystalline-Phase Evolution Enable Large-Capacity and Long-Life Na-Ion Batteries

Abstract

Two-dimensional (2D) antimonene is a promising anode material in sodium-ion batteries (SIBs) because of its high theoretical capacity of 660 mAh g and enlarged surface active sites. However, its Na storage properties and sodiation/desodiation mechanism have not been fully explored. Herein, we propose the sodiation/desodiation reaction mechanism of 2D few-layer antimonene (FLA) based on results acquired by in situ synchrotron X-ray diffraction, ex situ selected-area electron diffraction, and theoretical simulations. Our study shows that the FLA undergoes anisotropic volume expansion along the a/b plane and exhibits reversible crystalline phase evolution (Sb ⇋ NaSb ⇋ NaSb) during cycling. Density-functional theory calculations demonstrate that the FLA has a small Na-ion diffusion barrier of 0.14 eV. The FLA delivers a larger capacity of 642 mAh g at 0.1 C (1 C = 660 mA g) and a high rate capability of 429 mAh g at 5 C and maintains a stable capacity of 620 mA g at 0.5 C with 99.7% capacity retention from the 10th to the 150th cycle. Considering the 660 mAh g theoretical capacity of Sb, the electrochemical utilization of Sb atoms of FLA is as high as 93.9% at a rate of 0.5 C for over 150 cycles, which is the highest capacity and Sb utilization ratio reported so far. Our study discloses the Na storage mechanism of 2D FLA, boosting promising applications of 2D materials for advanced SIBs.

2D V‐V Binary Materials: Status and Challenges

“…Among the emerging 2D materials, black phosphorene is a significant monoelemental 2D material owing to its robust direct bandgap, high hole mobility, unique anisotropic characteristic, and hole‐dominated ambipolar transport behavior . Subsequently, the cousins of black phosphorene, which are arsenene, antimonene, and bismuthene, have been successfully fabricated and become the important new members of 2D family . These 2D group‐VA materials possess different allotropes with fascinating properties, thus making them suitable for a broad range of applications, including electronics, optoelectronics, topological spintronics, bio‐applications, and energy devices …”

Emerging Applications of Elemental 2D Materials

“…The capacity remained stable and reversible over 50 cycles. Few‐layer Sb‐based batteries have also demonstrated a high capacity of 620 mAh g −1 at 0.5C, with a 99.7% retention of capacity over 150 cycles …”

Peering into Alloy Anodes for Sodium‐Ion Batteries: Current Trends, Challenges, and Opportunities

“…Aside from the engineering modification aforementioned, new research is directed to 2D Sb‐dubbed antimonene . The interlayer spacing of antimonene (3.8 Å) is able to accommodate Na + without significantly altering the c ‐axial lattice parameter, which enables it to sustain huge volume change upon reversible crystalline phase evolution.…”