文摘
The cubic garnet-type solid electrolyte Li7La3Zr2O12 with aliovalent doping exhibits a high ionic conductivity, reaching up to 鈭?0p>鈥?p> S/cm at room temperature. Fully understanding the Lip>+p> transport mechanism including Lip>+p> mobility at different sites is a key topic in this field, and Li7鈥?x鈥?yAlyLa3Zr2鈥?i>xWxO12 (0 鈮?x 鈮?1) are selected as target electrolytes. X-ray and neutron diffraction as well as ac impedance results show that a low amount of aliovalent substitution of Zr with W does not obviously affect the crystal structure and the activation energy of Lip>+p> ion jumping, but it does noticeably vary the distribution of Lip>+p> ions, electrostatic attraction/repulsion, and crystal defects, which increase the lithium jump rate and the creation energy of mobile Lip>+p> ions. For the first time, high-resolution NMR results show evidence that the 24d, 96h, and 48g sites can be well-resolved. In addition, ionic exchange between the 24d and 96h sites is clearly observed, demonstrating a lithium transport route of 24d鈥?6h鈥?8g鈥?6h鈥?4d. The lithium mobility at the 24d sites is found to dominate the total ionic conductivity of the samples, with diffusion coefficients of 10p>鈥?p> mp>2p> sp>鈥?p> and 10p>鈥?2p> mp>2p> sp>鈥?p> at the octahedral and tetrahedral sites, respectively.