Poly(2-aminoazulene) Filler-Improved PEO-Based Electrolyte for Highly Stable Solid-State Li-Metal Batteries

Poly(ethylene oxide) (PEO) is regarded as an attractive solid-state electrolyte in lithium-ion batteries (LIBs). However, relatively low ionic conductivity of pristine PEO is a critical bottleneck to boost high-performance solid-state LIBs. Herein, poly(2-aminoazulene) (PAAz) was synthesized using the oxidation polymerization strategy and acted as a polymeric filler in the fabrication of PEO-PAAz composite electrolyte. Compared with PEO electrolyte, the composite electrolyte had a better ionic conductivity (9.27 x 10(-6) vs 6.47 x 10(-5) S cm(-1) at 30 degrees C), Li+ transference number (0.21 vs 0.51), and suppression of Li dendrites. Consequently, the PEO-PAAz electrolyte paired Li/LiFePO4 cell had a high capacity (156 mAh g(-1) at 0.5 C, 1 C = 170 mA g(-1)) and stability (only 8% capacity loss after 300 cycles); these are better than those of the PEO-based cell (132 mAh g(-1), 45% capacity loss). In addition, the PEO-PAAz-based cell could run for 1200 cycles with 60% capacity retention at 1 C. This study provides both a new organic filler for PEO-based solid-state LIBs and a method of improving the performance of solid-state LIBs, especially in terms of a long lifetime.

Automated summary

Poly(2-aminoazulene) (PAAz) was synthesized using oxidation polymerization strategy and acted as a polymeric filler in PEO-PAAz composite electrolyte, significantly improving the ionic conductivity and stability of the electrolyte. This study provides a new organic filler for PEO-based solid-state LIBs and a method of enhancing the performance, especially in terms of long-term stability.