Polyvinylidene fluoride (PVDF)-based electrolytes have attracted significant attention for their potential use in solid-state lithium batteries (SSLBs) due to their superior electrochemical performance and safety. However, their low ionic conductivity and uneven lithium deposition hinder the further application of PVDF-based electrolytes. Herein, this work focuses on incorporating Ba0.6Sr0.4TiO3 (BST) ferroelectric ceramics into PVDF to form composite solid-state electrolytes (CSEs). The BST ferroelectric ceramics can create an intrinsic electric field that facilitates lithium-ion transport and enables uniform Li deposition. In addition, benefiting from the high dielectric constant of BST and dipoles generated from the asymmetric structure, PVDF–BST CSEs achieve a high ionic conductivity (1.79 × 10−4 S cm−1) due to more free lithium ions, a wide electrochemical window of 4.8 V (vs. Li/Li+) and a high Li+ transference number (0.37). The assembled Li|PVDF–BST|Li symmetrical cells can steadily cycle for 1100 h at 0.1 mA cm−2 at 25 °C. The assembled Li|PVDF–BST|LiFePO4 cells show long-term cycling stability with a capacity retention of 85.6% after 100 cycles at 0.5C and a capacity retention of 81.4% after 200 cycles at 1C. This work provides a new strategy for improving the performance of the PVDF-based electrolytes by incorporating ferroelectric ceramics.
Jian Wang,Baohui Wang,Pin Ma,Yifei Zhang,Honghong Gong,Biyun Peng,Sen Liang,Yunchuan Xie,Hailong Wang
ABSTRACT PVDF-based nanocomposites have gained significant focus in capacitors for their excellent dielectric strength, its multi-scale structural inhomogeneity is the bottleneck for improving the energy storage performance. Here, the composite components are optimized by the matrix modification, BST (Ba 0.6 Sr 0.4 TiO 3 ) ceramic fibrillation and surface coating. A series of PVDF/polymethyl methacrylate/lysozyme@BST nanofibers with continuous gradient distribution (PF-M/ m BST nf-g) are prepared by the concentration gradient-biaxial high-speed electrospinning. The finite element simulation and experiment results indicate that the continuous gradient structure is favorable for the microstructure and inhomogeneity of the electric field distribution, significantly increasing the breakdown strength ( E b ) and the permittivity ( ε r ), as well as effectively suppressing the interfacial injected charge and leakage current. As a result, the energy storage density ( U e ) of 23.1 J/cm 3 at 600 MV/m with the charge-discharge efficiency ( η ) of 71% is achieved compared to PF-M (5.6 J/cm 3 @350 MV/m, 65%). The exciting energy storage performance based on the well-designed PF-M/ m BST nf-g provides important information for the development and application of polymer nanocomposite dielectrics.
危险品化学品经营许可证（带存储）