Constructing VS4/Nb2O5/GO composite to facilitate rapid Na+ transport with internal and external synergy

Transition metal polysulfides/oxides typically perform high reversible capacities in sodium-ion batteries/capacitors (SIBs/SICs), but low conductivity and slow redox reaction kinetics are still the main challenges for achieveing fast kinetics. Here, we construct the VS 4 /Nb 2 O 5 /GO composite structure, which can promote the overall conductivity and structural stability through the GO and VS 4 bonding (V-C and S-C) on the surface. Meanwhile, the chain-like VS 4 and Nb 2 O 5 connected with the V-O chemical bond can accelerate the electron and ion transfer internally, thus enabling the internal structure exposed during the activation process. Additionally, the bonding of VS 4 and Nb 2 O 5 is calculated by density functional theory (DFT), indicating that the strong metallic properties of the composite. When as the anode material of SIBs, the specific capacity of 268.8 mA h g −1 can be maintained after 2000 cycles at a current density of 10 A g −1 . After that, SICs are assembled using activated carbon (AC) as the cathode, which exhibit 58.01 Wh kg −1 at high power density of 3800 W kg −1 . This unique composite structure design can provide a reference for achieving fast electron and ion transport both internally and externally to the electrode material.