High-Performance Composite Solid Electrolytes Enabled by Lithium-Embedded Prussian Blue Analogues for Solid-State Lithium-Ion Batteries

Composite solid electrolytes represent a promising approach in solid-state batteries, yet achieving both high ionic conductivity and interfacial stability remains challenging. In this work, we design high-performance composite electrolytes by incorporating lithium-embedded manganese Prussian blue analogues (Li-MnPBA) as functional fillers into a polyvinylidene fluoride (PVDF) matrix. The Li-MnPBA features an open framework, adjustable coordination environment, an expanded lattice (10.4684 Å), and tailored transition metal valence states. Its inherent lithium content and structural vacancies facilitate rapid Li+ diffusion and enhance interfacial stability. The incorporation of Li-MnPBA not only reduces the crystallinity of PVDF to promote amorphous region formation but also establishes continuous ion transport channels through its porous framework and transferable lithium ions. This dual effect significantly improves the ionic conductivity (1.63 × 10–4 S cm–1) and ion transference number (0.73) of the composite electrolyte. Additionally, it offers a wide electrochemical window (4.5 V) and robust mechanical strength, effectively suppressing lithium dendrite growth and enabling stable long-term cycling. When integrated into solid-state batteries, LiFePO4//Li cells deliver 131.4 mAh g–1 at 1C with 97.8% capacity retention after 150 cycles. Meanwhile, NCM811//graphite full cells demonstrate stable operation at a high rate. This research highlights the potential application of Li-MnPBA in composite electrolytes and presents a direction for the design of high-performance solid-state batteries.