Sponge-Like Cathode Material Self-Assembled from Two-Dimensional V₂O₅ Nanosheets for Sodium-Ion Batteries

A sponge-like V₂O₅ nanomaterial is prepared by a freeze-drying method and evaluated as a cathode material for sodium-ion batteries. The sponge-like structure is self-assembled from V₂O₅ nanosheets that can sustain high pressure (400 times their own weight), thus leading to a high structure stability. The numerous macropores in the spongy structure can effectively soak up the electrolyte. Moreover, the exposed (001) facet of the nanosheets is favorable for charge transfer at the electrolyte/electrode interface. The thin nanosheets along the [001] axis provide short diffusion pathways for sodium ions. Electrochemical experiments show that the material has a high discharge capacity of 216mAhg^-1 at a current density of 20mAg^-1. In addition, the material shows a good capacity retention of 73% in 100 charge-discharge cycles at a current density of 100mAg^-1. Im-pore-tant structures: A sponge-like structure is self-assembled from V₂O₅ nanosheets with exposed (001) facets through a freeze-drying method. As capable cathode materials for sodium-ion batteries, the 2D nanostructures exhibit a high discharge capacity of 216mAhg^-1 and remarkable capacity retention.