Ionic conductivity of LiHf2(PO4)3 with NASICON-type structure and its possible application as electrolyte in lithium batteries

Abstract

Este trabalho reporta medidas de condutividade iônica realizadas para o LiHf 2(PO 4)3 calcinado a 1100 °C. As respostas devidas aos grãos -in te rior e junção -puderam ser identificadas tanto nas curvas de impedância, como na parte real das curvas de condutividade vs. freqüência. A energia de ativação, associada ao movi men to dos íons Li + no in te rior dos grãos, é 0,33 eV, enquanto que aquela associada à condutividade to tal cc, está na faixa de 0,36-0,47 eV. os resultados desta última dependem da contribuição relativa devida ao in te rior e à junção de grão. A possível aplicação do LiHf 2(PO 4)3 como eletrólito foi testada para a pilha Li/LiHf 2(PO 4)3/LiMn 2O4. Observou-se que o potencial de equilíbrio aumenta de 0,076 V a 2,217 V, quando a temperatura varia de 28 a 148 °C.The ionic con duc tiv ity of LiHf 2(PO 4)3 cal cined at 1100 °C has been mea sured. Grain in te rior and grain bound ary re sponses can be dis tin guished in the im ped ance plots as well as in the real part of con duc tiv ity vs fre quency plots. The ac ti va tion en ergy as so ci ated with the mo tion of Li + ions in side the grains is 0.33 eV while the ac ti va tion en ergy cor re sponding to the to tal dc con duc tiv ity changes from 0.36 to 0.47 eV, de pend ing on the rel a tive con tri bu tion of grain in te rior and grain bound ary. The pos si ble ap pli ca tion of LiHf 2(PO 4)3 as an elec tro lyte has been tested in the Li/LiHf 2 (PO 4 ) 3 /LiMn 2 O 4 cell. The equi lib rium poten tial in creases from 0.076 V to 2.217 V when the tem per a ture is raised from 28 to 148 ºC.Key words: NASICON, ionic con duc tiv ity, lith ium haf nium phos phate, solid state lithium bat ter ies Ar ti cle

Oxide Electrolytes for Lithium Batteries

“…A similar unstability under reduction potential has also been observed for LAGP with a lower threshold value of 0.648–0.85 V versus Li + /Li . LiHf 2 (PO 4 ) 3 is considered stable against Li metal, but the requirement for high‐temperature (above 1100°C) annealing to transform into a high ionic conducting phase could be an obstacle for the practical application …”

Analysis of thermal and electrical conductivity properties of Al substitution LiHf2(PO4)3 chemical solid electrolyte

“…The XRD results of unsubstituted LHP shows the sample powder sintered at 1100 °C for 3 h exhibited single phase with no secondary phases as reported elsewhere [16]. The unit cell volume and lattice parameters of the LHP analyzed are shown in Table 2 and the parameters are found to be in close agreement with the data reported by Chang et al [17,18] where a = b = 8.8285 Å, c = 22.0190 Å and V = 1484.40 Å 3 .…”

Cation mobility in Li1 + x Hf2 − x Sc x (PO4)3 NASICON-type phosphates

“…The preparation of a lithium hafnium phosphate by solid state reactions was described in Refs. [14,15]. As shown in those studies, heat treatment at 1270 K or higher temperatures leads to the formation of a NASICON type lithium hafnium phosphate with a hexagonal structure [14].…”

“…[14,15]. As shown in those studies, heat treatment at 1270 K or higher temperatures leads to the formation of a NASICON type lithium hafnium phosphate with a hexagonal structure [14]. Below 273 K, the lithium hafnium phosphate has a tri clinic structure.…”