| Sodium-sulfur battery is a typical electrochemical energy storage power supply,which has attracted much attention in many countries.In the whole battery system,?"-Al2O3 ceramic is considered as the most important core component,it only work as an electrolyte,but also as a diaphragm.Therefore,it plays an important role in improving the performance of sodium sulfur battery.At present,the content of ?"-Al2O3 phase prepared by traditional method is relatively low.Moreover,much grain boundary makes the ion migration path twist and turn,due to the random orientation of ?"-Al2O3 crystal in polycrystalline state.In this paper,?-AlOOH with controllable morphology was prepared by hydrothermal reaction,and it was also the Aluminum source for ?"-Al2O3 preparation.Furthermore,a high-content phase with a higher conductivity fabrication process was explored for industial production.The work mainly includes the following three terms:Firstly,?-AlOOH was prepared by the hydrothermal method.The effect of hydrothermal conditions on the morphology was studied and the hydrothermal formation mechanism of ?-AlOOH was analyzed.It is revealed that excessive H+ ions are necessary conditions for the destruction of interlayer hydroxyls and formation rod-like structures.The imapct of hydrothermal reaction parameters on the aspect ratio was studied by orthogonal test method,It was found that the concentration of AlCl3 with 0.3 mol/L,the solution of PH=5,and insulation at 200 ? for 24 hours is the best condition for the preparation of the large diameter ratio structure.The thermal decomposition process of ?-AIOOH was studied and the morphology of ?-AlOOH could be topologically inherited after thermal decomposition.?-AIOOH was used as the Aluminum source,mixed with Na2CO3 in proportion of Na:Al=1:5,and MgO added as stabilizer,then mixed directly and sintered at different temperatures(1350 ??1500 ?).The effect of sintering temperature on the content of ?"-Al2O3 phase in the final product was studied.The results showed that the content of ?"-Al2O3 phase was 89.6%for the materials which was sintered at 1450 ?.Furthermore,the ?-AIOOH was precalcined at different temperatures(500 ??1300 ?)and mixed with Na2CO3 and MgO,then sintered at 1450 ?.The effect of precalcining temperature on the content of ?-Al2O3 phase was studied.The results showed that the phase content of the sintering product was up to 95.64%when the precalcining temperature was 1100 ?.It was concluded that the Na+ ions intercalation behavior leaded to inherit the shape of ?-AIOOH unsuccessful.The ?-AIOOH precalcined at the same temperature as in the above experiment(500??1300 ?),then mixed with Na2CO3 and MgO.The mixture powders were uniaxially pressed and followed by sintered at 1450 ? for 3 h.The results showed that the ?"-Al2O3 phase content was reached 95.72%for the sample which was precalcined at 1100 ?.The SEM results showed that the sintered samples were mainly composed of sheet structure.Above all,the electrical property of the sample was also studied,the result showed that the relationship between electrical conductivity and temperature complied with the Arrhenius formula.And the maximum conductivity was 0.017 S·cm-1 at 300 ?. |
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