Organic montmorillonite modified polyethylene oxide based polymer electrolyte for dendrite-free flexible solid-state lithium metal batteries

Polyethylene oxide (PEO) based solid-state electrolytes are known for the low manufacturing cost and excellent processability, but their practical application is paved with thorns including the inferior ionic conductivity, low Li+ transfer number and insufficient Li dendrite blocking ability. Herein, we propose organic montmorillonite (OMMT) with expanded layer spacing (1.97 nm) as versatile fillers to construct PEO-OMMT electrolyte, in which OMMT not only increases Li+ transfer number (0.56) and ionic conductivity (7.15 × 10−4 S cm−1), providing fast ionic transport channels, but also endows PEO with high mechanical strength, resulting remarkable Li dendrite blocking ability (>2100 h). Additionally, the high dielectric constant and Lewis-rich polar sites of OMMT facilitate the dissociation of lithium salts and the rapid formation of LiF and Li3N-rich solid electrolyte interface layers. Impressively, the LiFePO4|PEO-OMMT|Li cell shows a high initial capacity (154.4 mAh g−1 at 0.5C) with ultralong cycling lifespan (>1200 cycles). Similarly, the LiNi0.83Mn0.05Co0.12O2|PEO-OMMT|Li cell retains a high discharge capacity of 151.5 mAh g−1 after 100 cycles at 0.2C. This work highlights the indelible contributions of OMMT functionalized fillers in improving the interfacial stability of PEO based solid-state electrolytes, paving a feasible avenue for the practical application of solid-state lithium metal batteries.