Self-limiting electrode with double-carbon layers as walls for efficient sodium storage performance

As a promising energy storage device, sodium ion batteries (SIBs) have attracted more and more attention. Nevertheless, the radius of a sodium ion is much larger than that of a lithium ion, and it is still a significant challenge to solve the problem of volume expansion. In order to solve the problem of volume expansion, a rational nanostructure consisting of CNTs as a carbon matrix, and were sequentially coated with mesoporous SnO2 and N-doped porous carbon tube (NCT). Mesoporous SnO2 can alleviate the volume expansion caused by charge and discharge, and the N-doped porous carbon layer can further inhibit the volume expansion of SnO2. When used as an anode material in sodium ion batteries, the CNT@ SnO2@ NCT heterostructure achieves efficient capabilities (350 and 150mA h g-1 at current densities of 0.1 and 2 A g-1, respectively).