Constructing a Highly Functional Oxygen Defect NaTi₂(PO_4-y)₃-TiO₂-PAN 3D Nanofibrous Network for High-Rate and...

Solid-state batteries are increasingly regarded as a key future energy storage option because they are highly safe and exhibit increased energy density, enabling them to address the drawbacks of traditional liquid lithium-ion batteries. Nevertheless, their industrial deployment is still hindered by obstacles, including significant interfacial resistance, limited ionic conductivity, and inadequate interface stability. To address these limitations, this work introduces a combined approach that employs defect modulation alongside rational structural design. A three-dimensional nanofibrous network composite solid electrolyte (NATP-TiO₂-PAN) was fabricated via electrospinning, incorporating Al³⁺-doped oxygen-deficient NaTi₂(PO₄)₃ (NATP) and TiO₂ into a polyacrylonitrile (PAN) polymer matrix. Defect engineering via Al³⁺ doping introduces oxygen vacancies into the NATP framework. These vacancies broaden the electrochemical window and decrease the activation energy for Li⁺ transport, thereby enhancing Li⁺ mobility. Computational results indicate that the (110) crystal plane of NATP is strongly compatible with lithium metal, promoting stable Li⁺ adsorption and the formation of a passivated interface, thereby suppressing lithium dendrite growth. The NATP-TiO₂-PAN composite electrolyte demonstrates a high ionic conductivity of 1.06 × 10^-4 S cm^-1 at 60 °C and a wide electrochemical stability window of 4.5 V. The assembled Li|NATP-TiO₂-PAN|Li symmetric cell maintains stable cycling for more than 1100 h with minimal polarization, confirming effective dendrite suppression. Benefiting from the stabilized interface and mitigation of volume expansion, the assembled quasi-solid-state Li|NATP-TiO₂-PAN|FeS₂ battery delivers excellent cycling stability, retaining 350 mAh g^-1 after 800 cycles at 500 mA g^-1 and maintaining more than 50% capacity retention after 1500 cycles at 1000 mA g^-1. This work provides a promising material design strategy and experimental foundation for developing highly safe, high-performance quasi-solid-state lithium-ion batteries (QSSBs).