The primary crystallization temperature of an electrolyte is a critical parameter in the aluminum electrolysis process, determining the operating temperature of the electrolytic process. Therefore, the initial crystallization temperature is one of the most critical physicochemical properties of the electrolyte in the electrolytic aluminum process. However, the Na 3 AlF 6 -AlF 3 electrolyte system, which is predominantly used in industrial electrolysis systems, operates at high temperatures. Lowering the electrolysis temperature would lead to numerous issues, including reduced current efficiency and increased cell voltage. Therefore, we propose low-temperature aluminum electrolysis in the Na 3 AlF 6 -K 3 AlF 6 -Li 3 AlF 6 -AlF 3 -KF-Al 2 O 3 electrolyte system. The synergistic effect of K 3 AlF 6 and Li 3 AlF 6 on the initial crystallization temperature within this system was investigated. Results indicate that at a cryolite molar ratio (CR) of 1.7–2, each unit of K 3 AlF 6 added reduces the initial crystallization temperature by an average of 2–4°C, while each unit of Li 3 AlF 6 added lowers it by an average of 0.5–3.5°C. Analysis of the cold-quenched electrolyte phases indicates the formation of phases such as Na 5 Al 3 F 14 , K 2 NaAlF 6 , and Na 2 LiAlF 6 within the electrolyte system. This study systematically measured the initial crystallization temperatures of the Na 3 AlF 6 -K 3 AlF 6 -Li 3 AlF 6 -AlF 3 -KF-Al 2 O 3 electrolyte system. It significantly advances the progress of the aluminum electrolysis industry toward green and low-carbon development, opening new technical pathways for achieving energy conservation and emission reduction targets in aluminum electrolysis production processes. Graphical
Jie Biao,Bing Han,Yidan Cao,Qidong Li,Guiming Zhong,Jiabin Ma,Likun Chen,Ke Yang,Jinshuo Mi,Yonghong Deng,Ming Liu,Wei Lv,Feiyu Kang,Yan-Bing He
Poor ion and high electron transport at the grain boundaries (GBs) of ceramic electrolytes are the primary reasons for lithium filament infiltration and short-circuiting of all-solid-state lithium metal batteries (ASLMBs). Herein, it is discovered that Li 2 CO 3 at the GBs of Li 7 La 3 Zr 2 O 12 (LLZO) sheets is reduced to highly electron-conductive LiC x during cycling, resulting in lithium penetration of LLZO. The ionic and electronic conductivity of the GBs within LLZO can be simultaneously tuned using sintered Li 3 AlF 6 . The generated LiAlO 2 (LAO) infusion and F-doping at the GBs of LLZO (LAO-LLZOF) significantly reduce the Li 2 CO 3 content and broaden the energy bandgap of LLZO, which decreases the electronic conductivity of LAO-LLZOF. LAO forms a 3D continuous ion transport network at the GB that significantly improves the total ionic conductivity. Lithium penetration within LLZO is suppressed and an all-solid-state LiFePO 4 /LAO-LLZOF/Li battery stably cycled for 5500 cycles at 3 C. This work reveals the chemistry of Li 2 CO 3 at the LLZO GBs during cycling, presents a novel lithium penetration mechanism within garnet electrolytes, and provides an innovative method to simultaneously regulate the ion and electron transport at the GBs in garnet electrodes for advanced ASLMBs.
危险品化学品经营许可证（带存储）