Ceramicized NASICON-based solid-state electrolytes for lithium metal batteries

Abstract

In this work, we have developed ceramicized hybrid solid state electrolytes (SSEs), which consisted of poly (vinylidene fluoride-hexafluoro propylene) (PVDF-HFP), lithium bis (trifluoromethanesulfonyl)imide (LiTFSI) salt, and sodium superionic conductor (NASICON)-type Li1+xAlxTi2‒x(PO4)3 (LATP) powders for lithium-ion batteries (LIBs) utilizing lithium metal anode. Adopting the sol–gel synthesis technique followed by a thermal calcination at 850 °C, we synthesized round-like LATP powders with an average particle size of ~ 30 μm. Engineering the LATP content (~ 45 wt.%) within the hybrid SSEs, we were able to achieve thermal stability along with superior ionic conductivity (i.e., 1.40 × 10−4 S cm−1 at 30 °C). Employing the Arrhenius plot in the temperature range of 30‒70 °C, the activation energy for the ionic conduction was lowered significantly (i.e., 0.21 eV) compared to prior efforts reported in the literature (i.e., 0.27 − 0.35 eV). The application of highly optimized SSE within a LIB with lithium metal anode resulted in the maximal capacity of ~ 162 mAh g−1 at 0.1 C. The cyclic performance of the battery utilizing such an optimized SSE configuration was very robust with a highly stable coulombic efficiency (~ 96.7%) after 100 cycles. Indeed, the ceramicized LATP-based SSEs developed in this work, can be employed for boosting the ionic conductivity, specific capacity, and cycle life while mitigating the interfacial resistance of the electrolyte/electrode layer for LIBs with lithium metal anode.