Strain Retarding in Multilayered Hierarchical Sn-Doped Sb Nanoarray for Durable Sodium Storage

摘要

Antimony (Sb) is a potential electrode material for sodium (Na) storage dueto its high theoretical capacity of 660 mAh g?1. Yet, the alloy/dealloy reactionbetween Na and Sb induces detrimental structural strain that inevitably leadsto electrode failure, further resulting in deteriorated rate performance and cyclelife. Herein, inspired by the multilayered structure of the pine trees, 3D hierarchicalmultilayered tin (Sn)-doped Sb nanoarray coated with a thin carbon(C) layer (Sb(Sn)@C) is developed. Density functional theory calculation resultssuggest that Sb(Sn)@C offers better kinetic properties for Na diffusion, andlower volume expansion upon sodium intercalation as compared to the counterpartswithout Sn dopant or carbon coating. Moreover, the simulation resultsbased on finite element analysis suggest that the unique hierarchical multilayeredconstruction not only provides highly efficient Na~+ utilization, but alsobuilds a uniform von Mises stress distribution that effectively confines structuralstrain induced during Na~+ insertion. This is also verified by nanoindentationmeasurement that Sb(Sn)@C shows higher elastic modulus and hardnessthan Sb(Sn) and pure Sb, indicating best mechanical stability. As expected,Sb(Sn)@C achieves excellent electrochemical capability for sodium storage withhigh reversible capacity, enhanced cyclability, and remarkable rate performance.