Functional LiTaO ₃ filler with tandem conductivity and ferroelectricity for PVDF-based composite solid-state electrolyte

Abstract

The composite solid-state electrolytes are gathering significant attention for combining both the advantages of inorganic and polymer electrolytes. However, after years’ research, conventional ceramic fillers offer limited ion conductivity enhancement in composite solid-state electrolytes due to the space charge layer that exists between polymer matrix and ceramic phase. In this study, we develop a ferroelectric ceramic ion-conductor (LiTaO₃) as a functional filler to alleviate the space charge layer and provide extra Li⁺ transport pathway tandemly. The obtained composite solid-state electrolyte comprising of LiTaO₃ filler and poly(vinylidene difluoride) matrix (P-LTO15) achieves an ionic conductivity of 4.90 ×10⁻⁴ S cm⁻¹ and a Li⁺ transference number of 0.45. It is proved that the polarized ferroelectric LiTaO₃ creates a uniform electric field and promotes a homogenous Li plating/stripping which renders the Li symmetrical batteries an ultra-stable cycle life for 4000 h at 0.1 mA cm⁻² and a low polarization over-potential (~50 mV). Furthermore, the solid-state NCM811/P-LTO15/Li full batteries achieve an ultra-long cycling performance (1400 cycles) at 1 C and a high discharge capacity of 102.1 mAh g⁻¹ at 5 C. This work sheds light on the design of functional ceramic fillers for composite solid-state electrolytes to effectively enhance ion conductivity and battery performance.