Porous Li1.3Al0.3Ti1.7(PO4)3@PMMA/PVDF-HFP composite solid electrolyte with tunable PMMA ratio: Constructing efficient ion channels and stable interface

Dendrite growth and interfacial instability in conventional liquid electrolytes limit the practical application of lithium metal batteries (LMBs). Composite solid electrolytes (CSEs) offer a promising alternative, yet challenges remain in achieving high ionic conductivity and low interfacial resistance. In this study, a series of sponge-like porous Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 @PMMA/PVDF-HFP CSE membranes (LPPH1:x) were fabricated via phase separation-solution casting. A multistage ion transport channel was constructed through the synergistic combination of the polymer matrix, inorganic fillers, and liquid electrolytes. The incorporation of PMMA suppressed the crystallization of PVDF-HFP, while the ester groups in PMMA facilitated Li salt dissociation through coordination with Li + . LPPH1:3 exhibited optimal comprehensive performance: a high ionic conductivity of 2.75 × 10 −3  S·cm −1 at room temperature, a Li + transference number of 0.62, and an electrochemical stability window of 4.9 V. Moreover, the symmetric cell demonstrated stable cycling for over 2000 h at 0.2 mA·cm −2 . The LiFePO 4 full cell retained 96.4% capacity after 200 cycles at 0.5C. Post-cycling characterization confirmed that LPPH1:3 suppressed lithium dendrite growth and maintained a stable interfacial structure. This work provides an innovative material design strategy and theoretical foundation for developing high-performance solid-state LMBs.