Highly stable sodium storage in 3-D gradational Sb–NiSb–Ni heterostructures

Abstract

Active/inactive alloyed systems in battery materials have been shown to relieve the agglomeration of active materials during cycling, thus exhibiting enhanced cyclability. However, the immoderate interaction between active and inactive elements can reduce the capacity of active materials. The present study realized a compositionally gradational heterostructure composed of a Ni core, NiSb interface, and attached Sb crystals via pulsed electrodeposition under controlled conditions. The 3-D Sb/NiSb/Ni electrode showed highly stable cycling performance for sodium storage at the expense of capacity decrease (391mAhg−1 at a current rate of 66mAg−1 after 300 cycles). High-resolution transmission electron microscopy analysis of the cycled samples revealed that the reversible solid-state reaction occurs between Sb/NiSb/Ni and Na3Sb/NaSb/Ni heterostructures during sodiation/desodiation. The cycling stability was attributed to the strong interaction between Ni and Sb.