LaNbO_(4)掺杂对Na-β"-Al_(2)O_(3)固态电解质性能的改善

Improvement in Properties of Na-β"-Al_(2)O_(3) Solid Electrolyte with LaNbO_(4)Doping

离子导体陶瓷材料的高断裂强度和优异热稳定性对于解决目前困扰碱金属电池发展的热失控问题具有重要意义,但其在室温下表现出的较高离子传输阻力限制了全固态电池的实际性能。以Na-β"-Al_(2)O_(3)(SBA)这一具备独特层状二维Na^(+)传导结构的离子导体陶瓷为研究对象,通过合成具备“微弹性”特点的LaNbO_(4)陶瓷作为第二相来对SBA的晶粒间隙进行填充修饰,以改善SBA在室温下的离子传导性能。结果表明,0.50 wt.%的LaNbO_(4)掺入量对SBA的提升效果最佳,修饰后的SBA室温离子电导率达到了2.061 mS·cm^(-1)。对应的活化能也从纯相SBA的0.1714 eV降低到了0.1545 eV。陶瓷横截面的SEM图像表明,合适比例的LaNbO_(4)掺入不仅提高了SBA的烧结致密度,也改善了SBA的晶体生长趋势,因此修饰后的SBA的阻抗值发生了降低。在室温全固态对称钠电池的恒流循环实验中,使用掺杂SBA组装的对称电池能够以更低的电压运行也从实验层面上印证了上述观点。

High fracture strength and excellent thermal stability of ion-conducting ceramic materials are important factors for solving the thermal runaway problem currently plaguing the development of alkali-metal batteries,but the high ion-transport resistance they exhibit at room temperature limits the practical performance of all-solid-state batteries.Na-β"-Al_(2)O_(3)(SBA),an ionic conductor ceramics,with a unique layered two-dimensional Na^(+)conduction structure,is explored.LaNbO_(4)ceramics with"microelastic"characteristics were synthesized as the second phase to fill and modify the grain gap of SBAs to increase their room temperature ionic conductivity.In the experiment,0.50 wt.%LaNbO_(4)is optimal in terms of enhancement effect,with a room temperature ionic conductivity of 2.061 mS·cm^(-1).The activation energy of the doped SBA was also reduced to0.1545 eV from 0.1714 eV for the pure phase SBA.SEM images of the ceramic cross-section showed that the appropriate content of LaNbO_(4)not only enhanced the sintering behavior of the SBAs,but also boosted the crystallization of the SBAs,thus leading to a reduction in the impedance.Symmetric all-solid-state sodium batteries assembled with the doped SBAs could be operated at lower voltages in constant-current charge/discharge at room temperature.