Pseudo-antiperovskite 구조인 Li2OHCl계의 이온전도도와 전기화학적 안정성 연구

Abstract

Recently, Li3OX (X=Cl, Br) called lithium rich antiperovskite electrolyte have been studied by Los-Alamos Lab. Because the materials have low melting point and high electrochemical stability, these materials have showed low interface resistance causing good ionic conductivity (10-6-10-3 Scm-1) by melting method and high anodic electrochemical stability. But, the materials have also showed air sensitivity and difficult synthesis conditions. Li2OHX (X=Cl, Br) replaced from one Li to one H have some advantages such as short time and low temperature for calcination but showed low ionic conductivity. To overcome this problem, we investigated Li2(OH)0.9X0.1Cl and Li2OH0.8X0.2Cl (X=F and Br) to study the size effect of halogens and improved ionic conductivity and electrochemical stability mechanism by the substitution at the doping site. The substituted materials exhibited the improved electrochemical stability and Li+ conductivity than Li2OHCl which is pristine material. Among these materials, Li2(OH)0.9F0.1Cl showed the higher chemical and electrochemical stability due to strong chemical binary bond such as Li-F and H-F than Li-Br and H-B. Li2(OH)0.9Br0.1Cl also showed highest Li+ conductivity because of larger interstitial site, phonon softening, and low OH- concentration. Comparison with the Li+ conductivity of Li2(OH)0.9F0.1Cl and Li2OHCl0.8Br0.2, the Li+ conductivity of the antiperovskite electrolytes is more influenced by the concentration of OH than other mechanisms.