LITHIUM-CARBONATE AS A SOLID ELECTROLYTE

To make clear the property of Li2CO3 as a solid electrolyte, a study was made on the electrical properties of Li2CO3 doped with Li3PO4, CaCO3 and LiNO3 as a function of dopant concentration at 250-600-degrees-C. The samples were prepared by a melt-solidifying technique. Since the crystals grew essentially along the (002) plane of the monoclinic Li2CO3 Structure, the conductivity, sigma, was measured by impedance spectrometry both along and perpendicular to (002) using gold paste as electrodes. By the Tubandt method, Li2CO3 was a pure lithium ion conductor. The conduction along (002) was much larger than that perpendicular to (002). The conductivity of Li2CO3 was similar in magnitude, to that of Li4SiO4, Li5AlO4 and Li2SO4. The conductivity increased proportionally with.the Li3PO4 concentration, and decreased with an increase in LiNO3 and CaCO3 concentration. It was concluded that the conduction in Li2CO3 is essentially by interstitial lithium ions. The Frenkel constant and the mobility of lithium interstitial ions were calculated.