전고체리튬전지용 Ag 도핑된 NASICON 유형의 Li1.3Al0.3Ti1.7(PO4)3 고체전해질의 이온전도도와 전기화학적 성능연구

Abstract

Recently, all-solid-state lithium batteries have received attention because of the electrochemical performance, safety, and reliability as well as high energy densities. NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) oxide-based solid electrolyte shows the favorable mechanical property, high Li+ transfer number, and excellent electrochemical and thermal stability. Water-soluble binders were introduced in order to increase the ionic conductivity of LATP. Silver was successfully substituted to the LATP solid electrolyte using a modified solid-state method for all-solid-state lithium batteries (ASSLBs). The pristine LATP was also synthesized for comparison before and after silver modification. The water-soluble binders was added to the mixture of solid electrolyte before sintering process to increase the ionic conductivity of solid electrolyte. The XRD, SEM, and EDS mapping confirmed the structural properties of LATP and silver-modified LATP Li1.3Al0.4Ag0.1Ti1.6(PO4)3. X-ray diffraction patterns showed the peak shifting after the addition of various binders were shown as the effect of the binders on the electrolyte. A similar peak with slightly increased and peak broadening for silver-modified LATP appeared after the addition of silver. There are also a small new peak appeared at around 46.5° theta degree indicating that the modification of silver on LATP has successfully synthesized. The ionic conductivity measurement was conducted by Electrochemical Impedance Spectroscopy (EIS) and revealed LATP with 1% PVA is currently displaying a highest value of 4.65 x 10-5 S/cm as binder for solid electrolytes. Cyclic voltammetry and DC-cycling for those solid electrolyte was measured to observe the stability of electrolyte against Li metal, and it revealed that the addition of water-soluble binders may improve the electrochemical stability of the solid electrolytes.