Amine-Functionalized Silane-Modified LATP Nanofillers in PVDF-HFP: A Quasi-Solid-State Electrolyte for Li-Ion Batteries

Quasi-solid-state electrolytes (QSSE) are a combination of solid-state electrolytes along with a small amount of ionic/liquid electrolyte into a solid matrix, which are the emerging materials in lithium-ion batteries. Here in this work, well-known potential candidates Li1.3Al0.3Ti1.7(PO4)3 (LATP, a solid-state inorganic electrolyte) and PVDF-HFP (a gel polymer electrolyte) were used to make the composite electrolyte. LATP is a NASICON-type Li-ion conductor that has garnered significant interest owing to the rapid Li+ conductivity and appreciable stability toward the air. The silane coupling agents (SCA) are an effective way to reduce particle aggregation and promote the uniform distribution of LATP over the PVDF-HFP matrix. It promotes the interaction between the organic–inorganic interface in the QSSE through the shared chemical bridging effect and the unique amino effect. To evaluate the optimum concentration of the gel-polymer electrolyte, the PVDF-HFP and LiClO4 concentrations were optimized, and the maximum ionic conductivity of 1.63 mS/cm was attained. Furthermore, the LATP was surface-modified with an amine-functionalized silane coupling agent (APTES) to enhance the interaction between PVDF-HFP and LATP. An amorphous layer was observed over the surface-modified LATP. The silane functionalization completely reveals the Lewis acid sites of LATP, while the −NH3+ from APTES in polysiloxanes further augments the anion adsorption capacity of LATP through electrostatic interactions. The highest ionic conductivity of 3.01 mS/cm was achieved with 5 wt % Si@LATP into the PVDF-HFP/LiClO4 matrix.