Search

Composite solid polymer electrolytes (CSPEs) have long been considered as one of the most promising candidates for all-solid-state lithium batteries owing to the merits of easy fabrication and low cost. However, the inorganic fillers physically mixed into the polymer matrix have weak polymer-filler interactions and tend to agglomerate, which limits the further improvement of the ionic conductivity and Li+ transference number of CSPEs. In this work, we demonstrated ZnO quantum dots can be chemically incorporated into the poly(ethylene oxide) (PEO) matrix by vapor phase infiltration (VPI), a special variant of atomic layer deposition (ALD). The ZnO quantum dots have strong chemical interactions with PEO polymer chains, which suppresses the crystallization of PEO and enhances the Li+ conduction. Due to the strong interactions, ZnO quantum dots distribute uniformly in the PEO-based solid electrolyte matrix as well as the top surface, which leads to a significant decrease of interfacial resistance with Li metal. As a result, the NCM811|Li half-cell with the VPI-ZnO/PEO/LiTFSI CSPE exhibit high discharge capacity at 50 ℃ (164.7 mAh g−1 at 0.5 C (1 C = 200 mA g−1), 2.8–4.25 V). This result could potentially serve as a model for a more general approach of using VPI to introduce strong polymer-filler interaction in CSPEs for high-performance lithium metal batteries.

Within a collaboration of Jiangsu Zhongtian and Beijing Jiaotong University, one phase of 220 kV/1.5 kA resistive type superconducting fault current limiter (SFCL) has been developed for testing. The current limiting unit of the SFCL consists of 8 series connected modules, and each of the module is composed of 16 parallel connected bifilar coils. The used high temperature superconductor (HTS) is the 12 mm wide steel-stabilized YBCO conductor supplied by Shanghai Superconductor. The current limiting unit is assembled in a cryostat with liquid nitrogen. The device has been successfully subjected to steady-state tests, fault current limiting tests and insulation tests. According to the testing results, the SFCL passed 22 current limiting tests at various prospective fault currents between 10 and 63 kArms for a fault duration of 100 ms, and the maximum limiting resistance could be as high as 3.5 Ω. The power frequency test at 360 kVrms for 1 min and lightning impulse test at 850 kV(1.2 µs/50 µs) have been carried out according to the Chinese national standard GB 1094.3.