Boosting lithium storage performance of Co-Sn double hydroxide nanocubes in-situ grown in mesoporous hollow carbon nanospheres

Herein, facile in-situ synthesis of double hydroxide CoSn(OH)6 nanocubes within mesoporous hollow carbon nanospheres (MHCSs) has been successfully developed through solution impregnation and solid-phase molten reaction, using MHCSs as nanoreactors. Several CoSn(OH)6 nanocubes with side length of 50∼80 nm are encapsulated in every MHCS with a diameter of 300–400 nm. When CoSn(OH)6@MHCS is evaluated as an anode material for lithium-ion batteries, it achieves exceptional rate capability (1684 and 626 mAh g−1 at 0.1 and 10 A g−1) and excellent cycle performance (1512 mAh g−1 at 0.2 A g−1 after 140 cycles, 1023 mAh g−1 at 1 A g−1 after 400 cycles, 512 mAh g−1 at 5 A g−1 after 500 cycles). The outstanding electrochemical performance is mainly attributed to the unique “ship-in-a-bottle” encapsulation structure. The mesoporous carbon shells of MHCSs facilitate electrolyte penetration and electron transfer. The large inner cavity of MHCSs promotes full contact between CoSn(OH)6 with electrolyte, and accommodates free expansion/contraction of CoSn(OH)6. The semi-enclosed carbon shell prevents the detachment and aggregation of the inner CoSn(OH)6. These structure merits can remarkably enhance reaction kinetics and structure stability of CoSn(OH)6. The stable and high-capacity output of the full cell demonstrates the great potential of CoSn(OH)6@MHCS in practical applications.