Microstructural Insights Into LATP Ceramic Nanofibers for High‐Performance Quasi‐Solid‐State Batteries

Composite solid-state electrolytes (CPEs) offer great potential for advancing quasi-solid-state lithium metal batteries (QSLMBs) due to their high ionic conductivity, electrochemical performance, and thermal stability. However, conventional CPEs, formed by incorporating ceramic particles into polymer matrices, often fail to significantly improve critical current density and rate performance. This study presents a green synthesis of NASICON-type Li₁.₄Al₀.₄Ti₁.₆(PO₄)₃ ceramic nanofibers (LATP-NFs) via electrospinning. It optimizes parameters such as solvent type, polymer and LATP precursor concentrations, heating rates, and calcination temperatures to control LATP-NF microstructures. Embedding 30 wt.% LATP-NF (LATP-30) into a poly(vinylidene fluoride)-lithium bis(trifluoromethanesulfonyl)imide (PVDF-LiTFSI) matrix yields a CPE with reasonable ionic conductivity of 0.21 mS cm^-1 at room temperature (RT), good thermal and electrochemical stability (>5 V), and enhanced mechanical strength. LATP-30 effectively suppresses lithium dendrite growth, achieving a high critical current density of 10 mA cm^-2. The LFP|LATP-30|Li cell delivers 169 mAh g^-1 at 0.1 C and maintains capacities of 122, 111, and 101 mAh g^-1 at 3, 5, and 10 C, respectively. It retains 153 mAh g^-1 after 300 cycles, with 97% capacity retention at 0.5C. This work demonstrates a sustainable and non-toxic strategy for synthesizing LATP-NFs for high-performance QSLMBs.