Silane-modified Li6.4La3Zr1.4Ta0.6O12 in thermoplastic polyurethane-based polymer electrolyte for all-solid-state lithium battery.

The ceramic/polymer composite solid electrolyte prepared by a simple physical mixing method has the problem of packing agglomeration and uneven dispersion, resulting in excessive interface impedance, obvious polarization, and severe reduction in energy density of solid-state batteries eventually. Given this defect, a silane coupling agent (KH560) containing Si–O bonds with low rotational potential energy was introduced to modify the garnet-type solid electrolyte (Li6.4La3Zr1.4Ta0.6O12, LLZTO) and then a ceramic polymer composite particle (Si@LLZTO) was achieved, which could be distributed uniformly in a thermoplastic polyurethane (TPU) matrix. Besides, a reduction in the crystallinity of TPU was evoked by the great interfacial compatibility of the silane-modified inorganic fillers, thus the composite solid electrolyte (TPU-Si@LLZTO) exhibits higher ionic conductivity (2.9 × 10−4 S cm−1), a wider electrochemical window (5 V, vs. Li/Li+), and a higher ion transfer number (tLi+ = 0.40). Furthermore, TPU-Si@LLZTO electrolyte displayed long running stability over 1000 h, and excellent rate performance in all-solid-state batteries with the positive electrode of LiFePO4. In conclusion, functional silanes exhibited a positive effect in constructing a compatible solid–solid interface between inorganic fillers/polyurethane polymers and gave full play to the performance advantages of composite electrolytes. [ABSTRACT FROM AUTHOR]