Strong (001) facet-induced growth of multi-hierarchical tremella-like Sn-doped V2O5 for high-performance potassium-ion batteries

Potassium-ion batteries (KIBs) are promising alternatives to lithium-ion batteries (LIBs) due to the low-cost and abundant potassium resource. However, the large volume expansion and inevitable electrode pulverization during cycling are the urgent problems to be solved. Herein, the Sn element is introduced to form the Sn-doped V2O5 (denoted as SDVO) via partially replacing V by Sn. Strong (001) facet-induced growth promotes the conversion of V2O5 from nanoparticle to nanosheet. The multi-hierarchical structure is composed of the primary mesoporous structure, the secondary SDVO nanosheets and the tertiary three-dimensional (3D) tremella-like nanostructure. Notably, the 3D tremella-like nanostructure assembled by two-dimensional (2D) nanosheets can curb the volume expansion of the V2O5. Furthermore, the tremella-like architecture with abundant mesopores and large surface area can reduce the transmission path of K-ions and increase the reaction active sites. The first–principles calculations show Sn doping can induce the preferred orientation of (001) crystal facet in V2O5 and improve the overall electronic conductivity of SDVO. Benefiting from these designed features, the SDVO composite with optimized electrolyte exhibits a high capacity of 308 mAh g-1 at 0.1 A g-1 after 150 cycles and excellent cycle stability of 188 mAh g-1 even after 3000 cycles at 0.5 A g-1.