ABSTRACT
Using solid-state electrolytes (SSEs) with excellent thermal and electrical stability to replace liquid electrolytes, and assembling solid-state lithium-ion batteries (SSLIBs) is considered the best solution to these safety issues. However, it is difficult for a single electrolyte to have the characteristics of high ionic conductivity, low interface resistance, and high stability of the counter electrode at the same time. In this work, the composite polymer electrolyte membrane (CPE) of inorganic Li1.3Al0.3Ti1.7(PO4)3 (LATP) and organic poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) polymer was successfully prepared by traditional casting method. The addition of LATP (10 wt %) ceramic powder makes CPE membrane (CPE-10) exhibit excellent electrochemical performance: the lithium-ion transference number and electrochemical window are as high as 0.60 and 4.94 V, respectively. Moreover, the CPE-10 showed excellent Li-metal stability, thereby enabling the Li-Li symmetric cells to stably run for over 300 h at 0.1 mA/cm2 with effective lithium dendrite inhibition. When paired with a high-voltage LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode, the Li/CPE-10/NCM622 cell exhibited excellent electrochemical performance: the highest specific discharge capacity of 152 mAh/g could be conducted at 0.2C after 50 cycles corresponding to 100% Coulombic efficiencies. The prepared CPE-10 demonstrates excellent electrochemical performance, providing an effective design strategy for SSLMBs.
ABSTRACT
The need for safe storage systems with a high energy density has increased the interest in high-voltage solid-state Li-metal batteries (LMBs). Solid-state electrolytes, as a key material for LMBs, must be stable against both high-voltage cathodes and Li anodes. However, the weak interfacial contact between the electrolytes and electrodes poses challenges in the practical applications of LMBs. In this study, a double-layered solid composite electrolyte (DLSCE) was synthesized by introducing an antioxidative poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)-10 wt % Li1.3Al0.3Ti1.7(PO4)3 (LATP) to the cathode interface, whereas a lithium-friendly poly(oxyethylene) (PEO)-5 wt % LATP was made to come into contact with Li metal. Owing to the heterogeneous double-layered structure of the DLSCE, a high ionic transfer number (0.43), high ionic conductivity (1.49 × 10-4 S/cm), and a wide redox window (4.82 V) were obtained at ambient temperature. Moreover, the DLSCE showed excellent Li-metal stability, thereby enabling the Li-Li symmetric cells to stably run for over 600 h at 0.2 mA/cm2 with effective lithium dendrite inhibition. When paired with a high-voltage LiNi1/3Co1/3Mn1/3O2 cathode, the Li/DLSCE/NCM111 cell exhibited excellent electrochemical performance: long-term cyclability with 85% capacity retention could be conducted at 0.2C after 100 cycles corresponding to 100% Coulombic efficiencies.
ABSTRACT
Lead-free ceramics, SrBi2Nb2O9-xBi2O3 (SBN-xBi), with different Bi contents of which the molar ratio, n(Sr) : n(Bi) : n(Nb), is 1 : 2(1 + x/2) : 2 (x = -0.05, 0.0, 0.05, 0.10), were prepared by conventional solid-state reaction method. The effect of excess bismuth on the crystal structure, microstructure and electrical properties of the ceramics were investigated. A layered perovskite structure without any detectable secondary phase and plate-like morphologies of the grains were clearly observed in all samples. The value of the activation energy suggested that the defects in samples could be related to oxygen vacancies. Excellent electrical properties (e.g., d 33 = 18 pC N-1, 2P r = 17.8 µC cm-2, ρ rd = 96.4% and T c = 420 °C) were simultaneously obtained in the ceramic where x = 0.05. Thermal annealing studies indicated the SBN-xBi ceramics system possessed stable piezoelectric properties, demonstrating that the samples could be promising candidates for high-temperature applications.
