Highly-confined, micro-Sb/C@MXene 3D architectures with strengthened interfacial bonding for high volumetric sodium-ion storage

Abstract

High-theoretical-capacity antimony (Sb) anodes hold promise for high-performing sodium-ion storage, yet suffer from huge volume change. In solving this obstacle, traditional strategies normally incorporate nanosized Sb with low-density conductive materials, which, in turn, sacrifice volumetric performance. Here, we report micro-sized Sb particles (m-Sb) dually encapsulated in carbon layer and densely-packed Ti3C2Tx MXene network (m-Sb/C@MXene), forming a highly-confined composite with robust interfacial bonding of SbOC between m-Sb and the carbon layer, and COTi between the carbon layer and MXene. The m-Sb/C@MXene anode displays a high volumetric capacity of 482.6 mAh cm−3 and a high volumetric capacity retention of 407.1 mAh cm−3 after 100 cycles at 0.1 A/g. A high-rate capacity of 191.0 mAh cm−3 at 10 A/g has also been achieved. Such superior performance stems from its unique architecture highly confined by the conductive and elastic network, which can provide fast electron/ion transport and effectively buffer volume expansion. Furthermore, ex-situ X-ray diffraction reveals that this hierarchical structure not only stabilizes m-Sb but also enhances ion transport kinetics by promoting the amorphization of m-Sb, thus delivers the excellent capacity and rate performance. This work offers an effective design of high-volumetric-capacity anode materials for their practical applications in sodium-ion energy storage.