Jiali Xue,Kuibao Zhang,Daimeng Chen,Jianjun Zeng,Baozhu Luo
Ta-doped Li7La3Zr2O12 (Ta-LLZO) solid electrolyte ceramics were synthesized by solid-state sintering, spark plasma sintering (SPS) and SPS plus heat-treatment (two-step method) using LiOH·H2O, La2O3, ZrO2 and Ta2O5 as the raw materials. The Ta-LLZO samples prepared from these three routes are all in cubic phase structure. However, the solid-state method results in Ta-LLZO samples with different particle sizes and porous morphology, while the samples prepared by SPS route contain fewer internal voids and smaller particle size. The two-step method not only retains the high compactness of SPS samples, but also the increment of grain size. The SEM results demonstrate that Ta-LLZO sintered by the two-step method shows optimal electrical properties. And the total ionic conductivity is 4.6 × 10−3 S cm−1 at 150 °C and the activation energy is calculated to be 0.38 eV.
Li Yang,Qiushi Dai,Lei Liu,Dingsheng Shao,Kaili Luo,Sidra Jamil,Hong Liu,Zhigao Luo,Baobao Chang,Xianyou Wang
Solid electrolytes could address the increasingly urgent safety and energy density concerns of lithium-ion batteries. Among several kinds of solid electrolytes, Ta-doped Li 7 La 3 Zr 2 O 12 (Ta-LLZO) became a research hotspot because of its high Li-ion conductivity and chemical stability against Li-metal and air. However, the preparation of high quality LLZO ceramic electrolyte via conventional air ambient sintering method is still a big challenge due to the serious “Li-loss” and abnormal grain growth phenomenon during the long-time high-temperature sintering process . Herein, a new rapid ultra-high-temperature air ambient sintering method without mother powder (MP) is put forward for the preparation of high quality Ta-LLZO ceramic electrolyte. The rapid sintering strategy can effectively restrain “Li-loss”. Furthermore, it is demonstrated that the none-mother-powder method is superior to traditional mother-powder method. Ta-LLZO ceramics sintered without MP via this rapid sintering method own small grain size, tight grain boundary, dense microstructure and high conductivity. Specifically, the Ta-LLZO ceramic sintered at 1360 °C for 10 min without MP exhibits high conductivity (8.5 × 10 −4 S cm −1 at 25 °C) and high relative density (97%), which equate those made by hot pressing sintering method. Without MP, the sintering process can avoid a lot of material waste and simplify the operation process. Moreover, the rapid sintering process can sharply shorten sintering time and reduce energy consumption. Therefore, this low-cost high-efficient sintering strategy can be effectively used in the large-scale production of high-quality Ta-LLZO ceramic electrolyte.
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