固态电解质锂镧锆氧(Li_7La_3Zr_2O_(12))制备及第一性原理研究

固态电解质(SSE)是锂离子电池(LIB)的关键材料.Li_7La_3Zr_2O_(12)(LLZO)固体电解质是全固态锂离子电池开发中的关键部分.采用高温固相法制备了不同烧结温度后的四方Li_7La_3Zr_2O_(12)(t-LLZO)和立方Li_7La_3Zr_2O_(12)(c-LLZO),分析了两种样品的结构性能.800℃下烧结12小时的t-LLZO呈四方相,晶格尺寸为a=b=13.13064?,c=12.66024?,离子电导率为3.42×10~(-8)S·cm~(-1);1000℃下烧结12小时的c-LLZO呈立方相,晶格尺寸为a=b=c=13.03544?,离子电导率为8.48×10~(-5)S·cm~(-1).另基于密度泛函理论(DFT)的第一性原理计算了四方相和立方相的LLZO固体电解质材料的能带结构、晶格参数、态密度和键布居.通过理论计算解释了四方相LLZO离子电导率低于立方相LLZO的原因.

Preparation and First-principle studies of solid-state electrolytes Li7La3Zr2O12

Solid-state electrolytes(SSEs) is a key material for lithium ion batteries (LIB).Li7La3Zr2O12 (LLZO) solid electrolyte is a key part in the development of all-solid-state lithium ion batteries.Tetragonal Li7La3Zr2O12 (t-LLZO) and cubic Li7La3Zr2O12 (c-LLZO) sintered at different temperatures were prepared by high-temperature solid-state method. The structure and properties of the two samples were analyzed in this work. T-LLZO sintered at 800 °C for 12 hours is tetragonal phase with lattice sizes of a = b = 13.13064Å,c = 12.66024Å and ionic conductivity of 3.42 × 10-8 S · cm-1; The c-LLZO sintered at 1000 °C for 12 hours is cubic phase with lattice sizes of a = b =c=13.03544Å and ionic conductivity of 8.48 × 10-5 S · cm-1. Based on the first-principles of density functional theory (DFT), the band structure, lattice parameters, density of states and bond population of the Li7La3Zr2O12 (LLZO) solid electrolyte material in the tetragonal and cubic phases were calculated. The results explained the reason why the ionic conductivity of tetragonal Li7La3Zr2O12 is lower than that of cubic phase.