Constructing Enhanced Composite Solid-State Electrolytes with Sb/Nb Co-Doped LLZO and PVDF-HFP

• Published in: Applied sciences 2024-04, Vol.14 (7), p.3115
• Main Authors: Cai, Jinhai, Liu, Yingjie, Tan, Yingying, Chang, Wanying, Wu, Jingyi, Wu, Tong, Lai, Chunyan
• Format: Article
• Language: English
• Subjects: Batteries; co-doping; composite solid-state electrolyte; Density; Electrolytes; Energy; ionic conductivity; Li7La3Zr2O12; Lithium; Membranes; Polymers; Polyvinylidene fluoride; Sintering; Spectrum analysis
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app14073115

Composite solid-state electrolytes are viewed as promising materials for solid-state lithium-ion batteries due to their combined advantages of inorganic solid-state electrolytes and solid-state polymer electrolytes. In this study, the solid electrolytes Li6.7−xLa3Zr1.7−xSb0.3NbxO12 (LLZSNO) with Sb and Nb co-doping were prepared by a high-temperature solid-phase method. Results indicate that Sb/Nb co-doping causes lattice deformation in LLZO and increases the lithium vacancy concentration and conductivity of LLZO. Then, with the co-doped LLZSNO as an inorganic filler, a composite solid electrolyte of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) was prepared with a casting method. The obtained composite solid electrolyte exhibits a high ionic conductivity of 1.76 × 10−4 S/cm at room temperature, a wide electrochemical stable window of 5.2 V, and a lithium-ion transfer number of 0.32. The Li|LiFePO4 coin battery with the composite solid electrolyte shows a high specific capacity of 161.2 mAh/g and a Coulombic efficiency close to 100% at 1 C. In addition, the symmetrical lithium battery Li|Li with the composite electrolyte could cycle stably for about 1500 h without failure at room temperature.