A closed-ended MXene armor on hollow Sn4P3 nanospheres for ultrahigh-rate and stable sodium storage
Wufeng Fan, Yingxv Gao, Qunbo Hui, Zechao Ma, He Gan, Xiaohong Xia, Hongbo Liu
Abstract
The development of sodium-ion batteries has been seriously discouraged by the major limitation in the rate capability and the cycle life of the anode materials. Sn 4 P 3 is recognized as a potential anode for sodium -ion batteries owing to its ultrahigh specific capacity and low cost, but the great volumetric change and low intrinsic electrical conductivity severely limit the cycling performance. Herein, we propose a closed-ended MXene and Sn 4 P 3 hybrid consisting of active Sn 4 P 3 porous hollow nanospheres (Sn 4 P 3 HS) armored by a conductive MXene shell. Notably, the outer MXene shell protects Sn 4 P 3 from direct exposure to the electrolyte and only allows the inward expansion of Sn 4 P 3 into the hollow space, resulting in the formation of a thin solid-electrolyte interphase layer of high stability. As predicted, the hybrids can deliver an extraordinarily high capacity of 302.1 mAh g −1 even at an ultrahigh rate of 10 A g −1 and cycle at 1 A g −1 for 1500 cycles with a capacity retention of 94.9%. Moreover, the Sn 4 P 3 HS@MXene//Na 3 V 2 (PO 4 ) 3 /C full cell exhibits an outstanding energy density of 287.8 Wh kg −1 and good cyclic ability (390.5 mAh g −1 at 1A g −1 after 500 cycles), exhibiting a great potential in practical application.