纳米多孔β-Li_3PS_4固体电解质的溶剂脱除法制备及性能

Performance of Nano-porous β-Li_3PS_4 Prepared by Solvent Removing Method

以Li2S和P2S5为反应物,四氢呋喃为溶剂,采用溶剂脱除法制备了室温下稳定的高离子电导率β-Li_3PS_4晶体电解质,通过粉末X射线衍射、差热-热重分析、拉曼光谱、氮气吸附-脱吸和交流阻抗测试等方法对其性能进行表征,研究了热处理温度对溶剂脱除程度、固体电解质结晶状态、比表面积、孔隙率和离子电导率的影响.结果表明,该方法制备得到的β-Li_3PS_4晶体可以在室温下稳定存在.160℃加热条件下Li_3PS_4的离子电导率达到7.44×10-6S/cm.热处理过程中四氢呋喃分3个阶段脱除,导致产物颗粒表面和内部产生大量纳米孔.大量纳米孔洞的存在提高了材料的表面能,有利于新相形核,加快了相变速度,降低了相变温度,使β-Li_3PS_4晶体在室温下保持稳定.

Room temperature-stable and highly ionic conductive crystal electrolyte β-Li_3PS_4 was fabricated via solvent-removing method using Li2 S and P2S5 as reactants,tetrahydrofuran as solvent. Then β-Li_3PS_4 was analyzed through X-ray diffraction,differential thermal analysis and thermogravimetry analysis,Raman spectrometry,N2adsorption-desorption analysis and electrochemical impedance spectroscopy. Effects of heat treatment temperature on solvent removing,crystallization,specific surface area,porosity,and ionic conductivity were investigated. The results show that solvent-removing method successfully stabilizes β-Li_3PS_4 at room temperature. When heated at 160 ℃,Li_3PS_4 reaches its highest ionic conductivity,7. 44 × 10-6S / cm. During the heating treatment,tetrahydrofuran solvent was removed in 3 stages,generating numerous nanopores at both surface and interior of the Li_3PS_4 particles. Those nanopores increase surface energy,which helps new phase nucleate,expedites crystalline transition,reduces phase transition temperature,and stabilizes β-Li_3PS_4 to room temperature.