Fabrication of Li1.4Al0.4Ti1.6(PO4)3 quasi-solid electrolyte with high conductivity and compatibility through AAO template

Abstract

Employing inorganic ion conductors as solid electrolytes (SEs) is one promising solution to develop advanced all- and quasi-solid-state batteries with high energy and safety advantages. Among numerous Li+ ion conductors, Li1.4Al0.4Ti1.6(PO4)3 (LATP) has attracted extensive attention due to its preponderances of air stability and superior Li+ conductivity. However, the practical application of the LATP electrolyte is still obsessed by serious side reactions at the Li-electrode/electrolyte interface. In this work, one kind of quasi-solid electrolyte (QSE) is designed combining anodic aluminum oxide (AAO), LATP, and liquid electrolyte [LE, LiPF6/ethylene carbonate-dimethyl carbonate (EC-DMC)], wherein well-ordered LATP arrays are constructed in the AAO framework to facilitate ionic transport, and a certain content of the LE is introduced to reduce the interfacial resistances. The characterization results suggest that the ionic conductivity of as-prepared AAO–LATP–QSE (ALQSE) is boosted up to ∼6.50 × 10−3 S cm−1 with a Li+ transference number of 0.66, especially the interval between the LATP compound and the Li-metal electrode can effectively restrain Ti4+→Ti3+ reduction at the Li-anode/electrolyte interface. Thus, the assembled LiFePO4|ALQSE|Li cell exhibits excellent electrochemical stability, delivering an initial discharge capacity of 153.3 mAh g−1 at 0.1C and remaining 152.4 mAh g−1 after 60 cycles with a fairly mild reduction of 0.028% per cycle. This study not only presents a facile strategy to prepare a robust QSE framework employing an AAO template but also promotes the rational interface design between titanium (Ti)-containing solid-state electrolytes and Li-metal anodes.