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PVDF-based electrolytes are promising candidates for solid-state lithium batteries (SSLBs) due to their high safety, interface compatibility and electrochemical stability. However, the low ionic conductivity of PVDF and uncontrollable dendrite growth in the related SSLBs restrict their development and application. Herein, ferroelectric BiFeO3 is introduced into PVDF to improve its electrolyte performance. The developed PVDF-based composite electrolytes achieve a high ionic conductivity (1.39 × 10−4 S cm−1) and Li+ transference number (0.35). Benefitting from the introduced BiFeO3, the assembled Li symmetrical batteries exhibit good cycle performance and can steadily cycle for 2500 h at 0.1 mA cm−2, at 25 °C. Matched with LiNi0.8Co0.1Mn0.1O2 cathodes, the assembled batteries show excellent long-term cycling stability with a capacity retention of 94% after 100 cycles at 0.1C and capacity retention of 89% after 400 cycles at 0.3C. The ferroelectric effect of BiFeO3 restrains the inhomogeneous electric field and adjusts the Li+ distribution at the electrolyte/electrode interface, achieving uniform Li deposition. The ferroelectric BiFeO3 powder facilitates the decomposition of lithium salts and regulates the chemical composition of the solid electrolyte interphase (SEI). [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes (SPEs) with high ionic conductivity and electrochemical stability are crucial for the potential practical applications of solid-state lithium metal batteries. In SPEs based on polyvinylidene fluoride (PVDF), the addition of N,N-dimethylformamide (DMF) enhances ionic conductivity but reduces the electrochemical stable window. This work proposes a strategy to improve the stability of PVDF-based SPEs with high ionic conductivities using LiNO3 additive. By adding 5% of LiNO3 (comparing to the weight of LiTFSI lithium salt), the ionic conductivity of prepared PVDF-based SPEs achieves up to 10−4 S cm−1 at 30 ℃. The assembled Li|SPE|NCM811 cells with the LiNO3-modified SPE film as separator maintained a capacity retention rate of 93.0% after 200 electrochemistry cycles induced at a current density of 0.5 C. The influence of LiNO3 in the interface resistance, Li-ionic transfer number, solid electrolyte interface phase, and electrochemistry performance of LIBs is investigated. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) based on solid-state electrolytes have attracted much attention for their high safety and energy density. Li29Zr9Nb3O40 (LZNO), as a new kind of Li-ion conductor, has great potential in applications of solid-state LIBs. In this work, various contents of LiF are selected to modify LZNO Li-ion conductor, and the optimal content of LiF is 5 wt% (weight%). The phase component, crystal structure, ionic conductivity, and electrochemical performance are investigated. The refinement of crystallographic information based on the bond valence site energy theory is induced to reveal the possible lithium-ion migration channel. The results show that modification with LiF enhanced the 3D migration pathways and conductivity of LZNO-based electrolytes. The 5 wt% LiF modified LZNO presents total conductivity of 0.943 × 10−4 S cm−1 at ambient temperature and has low activation energy of conduction (0.16 eV). The cycle performance of the lithium symmetric cell characterizes the cycle of 140 h. [ABSTRACT FROM AUTHOR]

Hollow nanoboxes structure have raised great attention as microwave absorption materials on account of their ultralow density and large specific area. By introducing an adjustable interior cavity structure, the dielectric loss and microwave absorption performance were affected by the tunable complex permittivity and impedance matching was improved. In our study, hollow CoS2 nanoboxes with designable interspaces were successfully fabricated based on the surfactant-assisted solution method and followed by an in situ ion-exchange process. The structure, elemental compositions and morphology of the products were characterized by XRD, XPS, EDX, SEM and TEM, respectively. In addition, microwave absorption performance and the intrinsic mechanism are investigated in-depth. The paraffin-based composites with 20 wt.% filling contents exhibited superior microwave absorption capacities in view of both maximum reflection loss value (RLmax, −54.48 dB) and effective absorption bandwidth (EAB, below −10 dB, 6.0 GHz), which can be ascribed to unique hollow structure and good impedance matching. With these considerations in mind, this study provides a reference for the construction of high-performance microwave absorbers with unique hollow structure. [ABSTRACT FROM AUTHOR]