A lithium ion conductor in Li4SiO4-Li3PO4-LiBO2 ternary system

Highlight
• A lithium ion conductor with the composition as the mole ratio of Li4SiO4:Li3PO4:LiBO2 = 60:40:20
• A ternary solid solution with orthorhombic structure
• The ion conductivity of 5.7 × 10− 6 s/cm and Warburg coefficient (Aw) 17 kΩ·S− 1/2 at room temperature

We developed a lithium ion conductor in Li4SiO4-Li3PO4-LiBO2 ternary ceramic system comprising of the mole ratio as Li4SiO4:Li3PO4:LiBO2 = 60:40:20 (termed as 40LP + 20B), exhibiting the ion conductivity of 5.7 × 10− 6 s/cm at room temperature. From the X-ray diffraction patterns, the ternary solid solution has the orthorhombic phase structure with the increased unit cell volume due to the substitution of boron in lattice. The SEM images show that the high densification of the 40LP + 20B samples sintered at 900 °C for 6 h, and EDS mappings illustrate that the incorporating boron is distributed homogenously in the grains and no precipitated impurity was observed on grain surface or around grain boundaries. The data of electrochemical impedance spectroscopy (EIS) reveal the low resistance from grain boundary, giving rise to the high bulk ion conductivity. The lithium ion conductor in Li4SiO4-Li3PO4-LiBO2 system is of great potential as practical solid electrolyte for all-solid-state battery.