Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) is a promising solid-state electrolyte for Li-ion batteries,but Li-dendrite's formation greatly limits the applications.In this paper,we systematically investigate the st...Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) is a promising solid-state electrolyte for Li-ion batteries,but Li-dendrite's formation greatly limits the applications.In this paper,we systematically investigate the stability,electronic properties,and Li-ion mobility of the LLZO surface by the ifrst-principles calculations.We consider the(110) and(001) slab structures with different terminations in the t-and c-LLZO.Our results indicate that both(110) and(001) surfaces prefer to form Li-rich termination due to their low surface energies for either t-or c-LLZO.Moreover,with the decrease of Li contents the stability of Li-rich surfaces is improved initially and degrades later.Unfortunately,the localized surface states at the Fermi level can induce the formation of metallic Li on the Li-rich surfaces.In comparison,Li/La-termination has a relatively low metallic Li formation tendency due to its rather low diffusion barrier.In fact,Li-ion can spontaneously migrate along path II(Li3→Li2) on the Li/La-T(001) surface.In contrast,it is more difficult for Li-ion diffusion on the Li-T(001) surface,which has a minimum diffusion barrier of 0.50 eV.Interestingly,the minimum diffusion barrier decreases to 0.34 eV when removing four Li-ions from the Li-T(001) surface.Thus,our study suggests that by varying Li contents,the stability and Li-ion diffusion barrier of LLZO surfaces can be altered favorably.These advantages can inhibit the formation of metallic Li on the LLZO surfaces.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12064015 and 12064014)。
文摘Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) is a promising solid-state electrolyte for Li-ion batteries,but Li-dendrite's formation greatly limits the applications.In this paper,we systematically investigate the stability,electronic properties,and Li-ion mobility of the LLZO surface by the ifrst-principles calculations.We consider the(110) and(001) slab structures with different terminations in the t-and c-LLZO.Our results indicate that both(110) and(001) surfaces prefer to form Li-rich termination due to their low surface energies for either t-or c-LLZO.Moreover,with the decrease of Li contents the stability of Li-rich surfaces is improved initially and degrades later.Unfortunately,the localized surface states at the Fermi level can induce the formation of metallic Li on the Li-rich surfaces.In comparison,Li/La-termination has a relatively low metallic Li formation tendency due to its rather low diffusion barrier.In fact,Li-ion can spontaneously migrate along path II(Li3→Li2) on the Li/La-T(001) surface.In contrast,it is more difficult for Li-ion diffusion on the Li-T(001) surface,which has a minimum diffusion barrier of 0.50 eV.Interestingly,the minimum diffusion barrier decreases to 0.34 eV when removing four Li-ions from the Li-T(001) surface.Thus,our study suggests that by varying Li contents,the stability and Li-ion diffusion barrier of LLZO surfaces can be altered favorably.These advantages can inhibit the formation of metallic Li on the LLZO surfaces.
