NASICON型固态电解质LATP电化学性能及稳定性

Electrochemical property and stability of NASICON-type solid state electrolyte LATP

NASCION型磷酸钛铝锂Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)作为一种低成本、高锂离子电导特性的无机固态电解质材料,在高能量密度、高安全性的锂电池领域有着良好的应用前景。基于LATP固态电解质在正极材料及隔膜包覆领域的潜在应用,对其电化学性能及充放电结构变化过程进行全面评价。结果表明,LATP在锂离子电池体系中循环稳定性较差,充放电循环容量迅速衰减,导致这一现象的原因在于,LATP储锂容量的主要贡献来源于Ti^(4+)/Ti^(3+)的价态变化,但是该过程并不完全可逆,使得储锂容量骤降。同时,LATP会与电解液中含氟组分反应生成TiF3,使得Ti^(3+)向电解液中溶出。但是,在循环后LATP导电性有所增强,可能得益于材料表面形成的电子导电层,该特性将有助于其在正极材料表面包覆应用领域的性能发挥。因此,针对LATP在实际电池体系中的应用开发,未来仍需评估LATP结构变化对电池性能的影响,在充分发挥优势的基础上,进一步研究改善其电化学稳定性。

NASCION-type Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP) inorganic solid state electrolyte has low cost and high ionic conductivity,which leads to a good application prospect in the field of lithium batteries with high energy density and high safety.Based on the potential application of LATP solid electrolyte in the field of cathode materials and separator coating,the electrochemical performance and stability of LATP were studied in this paper.The results showed that LATP exhibited electrochemical instability in the lithium ion battery system with rapid capacity degradation.The storage capacity of LATP mainly depended on the Ti^(4+)/Ti^(3+)change between Ti^(4+) and Ti^(3+),which was partly reversible.At the same time,LATP also reacted with the fluorine-containing components in the electrolyte to form TiF3,so that Ti^(3+)dissolved into the electrolyte.However,the LATP showed enhanced electrical conductivity after cycles,due to the electronic conductive layer formed on the surface of LATP.This characteristic could play a positive role in the application field of cathode coating for LATP.In the future,it is still necessary to evaluate the impact of structural changes on the practical application performance of LATP,and further research is needed to improve the electrochemical stability of LATP.