Kun Shi,Changsong Yu,Long Zhou,Zhangxian Chen,Zeheng Yang,Weixin Zhang
Polyvinylidene fluoride (PVDF)-based solid-state polymer electrolytes always suffer from their intrinsic flammability, limited Li + transfer, and the interfacial degradation induced by high-activity residual N , N -dimethylformamide (DMF) solvent. Herein, a 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)-anchored PVDF-based solid-state electrolyte is synthesized by a two-step reaction involving PVDF dehydrofluorination and subsequent phosphorus-hydrogen addition. The covalent immobilization of DOPO on PVDF polymers endows the electrolyte with high flame retardancy while inhibiting phosphorus-associated reactions with lithium anodes. The alteration in polymer crystallinity and polarity significantly increases the relative permittivity of electrolyte and leads to a densely-interconnected spherulite network, facilitating the homogeneous Li + distribution and rapid transport. Remarkably, the DOPO-anchored polymers are involved in Li + solvation at the expense of DMF molecules, which effectively suppresses DMF decomposition on electrode surfaces and promotes formation of a robust anion-derived solid electrolyte interphase. The resultant polymer electrolyte demonstrates exceptional cycling stability, maintaining over 2500 h in symmetric lithium cell (0.1 mA cm −2 ) and 850 cycles in LiFePO 4 /Li cells (0.5 C) with 94.27% capacity retention. Furthermore, it enables stable operation in high-voltage LiNi 0.9 Co 0.05 Mn 0.05 O 2 /Li and practical pouch cells, while achieving high safety of batteries under abusive conditions. This work presents an innovative design in PVDF-based polymer electrolytes for safe and long-cycling solid-state lithium-ion batteries.
Flame-retarded epoxy thermosets are highly desirable for electronics-related basic materials in the new-generation information applications. Herein, a DOPO-anchored benzothiadiazole flame retardant, namely DOPO-BTD , is designed and synthesized for P/N/S synergistic flame-retarded epoxy thermosets. DOPO-BTD possesses good thermal stability and excellent compatibility with the epoxy matrix. As reflected by UL 94 test, the DOPO-BTD coated EP passes the V0 rating and achieves a higher LOI value of 34.6% at ultralow P content of 0.39 wt%. The investigation of the DOPO-BTD -triggered P/N/S synergistic flame-retarded effect by thermal images further validated the flame retarded efficacy and dramatic inhibition of the flame. Meanwhile, the incorporation of 4.8 wt% DOPO-BTD into the epoxy matrix, the PHRR, THR, SPR, TSP, and COP are significantly decreased by 37.97%, 27.44%, 25.49%, 19.83%, and 31.70%, respectively. Additionally, the fire growth index (FGI) is sharply dropped 26.06%. Moreover, the TGIR and TGMS results convince the flame-retarded mechanism of DOPO-BTD through the combination of the gas-phase and condensed-phase pathways. The P/N/S synergistic DOPO-BTD can serve as a promising flame retardant for efficiently fabricating the flame-retarded epoxy thermosets, and this study sheds light on the development of multiple elements synergistic flame-retardants for functional polymers with great application potential.
危险品化学品经营许可证（带存储）