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We synthesize Sb/Sb2O3 nanoparticles by the oxidation of Sb nanoparticles at 100, 200, and 300 °C. The half sodium-ion batteries with Sb/Sb2O3-200 exhibit the optimal performance with a charge capacity of 540 mAh g−1 after 100 cycles at 0.1 A g−1, maintaining up to six times more capacity than pure Sb, and superior rate performance with 95.7% retention after cycling at varied current densities. One reason for this is that Sb/Sb2O3-200 is at exactly the optimum ratio of Sb2O3:Sb and the particle size of Sb/Sb2O3 to ensure both high capacity for Na+ and small stress during sodiation/desodiation, which is confirmed by the diffusion–stress coupled results. It indicates that increasing the ratio of Sb2O3:Sb causes a decrease of Mises equivalent stress, radial stress, and tangential stress in the range of 1:1–3.5:1, and an increase in the range of 3.5:1–4:1. These stresses decrease with a particle radius in the range of 30–50 nm and increase with a particle radius in the range of 50–70 nm. Additionally, another reason is related to the formation of cycling-induced coral-like Sb, which can promote Na+ diffusion, relieve cycling-induced volume changes, and provide exceptional Na+ storage. [ABSTRACT FROM AUTHOR]

The application of vanadium redox flow batteries (VRFBs) has encountered challenges because the most commonly used commercial membrane (perfluorinated sulfonic acid, PFSA) has severe vanadium ion permeation, which yields poor stability of the battery. Herein, a PFSA‐based hybrid membrane with a sandwich structure created using a reinforced polytetrafluoroethylene thin layer with hydrophilic nanohybrid fillers is developed. The tungsten trioxide (WO3) nanoparticles are in situ grown on the surface of graphene oxide (GO) nanosheets to overcome the electrostatic effect, and to enhance the hydrophilicity and dispersibility of GO nanosheets, which is embedded in the PFSA matrix to act as a "barrier" to reduce vanadium ions permeation. In addition, these hydrophilic WO3 nanoparticles on GO nanosheets surface serve as proton active sites to facilitate proton transportation. As a result, at 120 cm−2, the cell of the hybrid membrane displays high Coulombic efficiency (over 98.1%) and high energy efficiency (up to 88.9%), better than the commercial Nafion 212 membrane at the same condition. These performances indicate the proposed hybrid membrane is applicable for VRFB application. Also, this design method of the membrane can be extended to other fields including water treatments and fuel cells. [ABSTRACT FROM AUTHOR]