Effect of Na₃BO₃ Addition into Na₃V₂(PO₄)3 single-phase all-solid-state batteries

To reduce the interfacial resistance between the electrodes and electrolyte in all solid-state battery, we have recently suggested the idea of a single-phase all-solid-state battery that is made from a single material with the three roles of electrolyte, positive electrode and negative electrode. In this research, the effects of Na₃BO₃addition into Na₃V₂(PO₄)3 were investigated with respect to the electrochemical properties. Na₃BO₃addition improved the relative density of Na₃V₂(PO₄)3 by acting as a flux to fill the voids of the sintered body, as confirmed by scanning electron microscopy (SEM) observations. The electrical conductivity is increased by the addition of Na₃BO₃, although the activation energy is also increased. Charge/discharge measurement revealed that Na₃V₂(PO₄)3+Na₃BO₃pellets exhibit improved cyclability and optical observation indicated a different mechanism for the in-situ formation of the electrode from a Na₃V₂(PO₄)3 pellet.