Ao Du,Haotian Lu,Sisi Liu,Shuoyi Chen,Zihui Chen,Wenhao Li,Jianwei Song,Quan-Hong Yang,Chunpeng Yang
Solid polymer electrolytes (SPEs) are among the most promising candidates for solid-state batteries due to their easy processibility, interface compatibility, and cost efficiency. However, the trade-off between the ionic conductivity and mechanical strength of SPEs, which has persisted for decades, hinders their application in solid-state lithium (Li) metal batteries. In this study, the aim is to break this trade-off by utilizing poly(p-phenylene benzobisoxazole) (PBO) nanofibers as a mechanically strong backbone and polyethylene oxide (PEO) as an ionically conductive network. The PBO/PEO composite electrolyte reduces the crystallinity of PEO while increasing the mechanical strength (74.4 MPa, ≈14 times that of PEO). Thus, PBO/PEO simultaneously improves ionic conductivity and mechanical strength both at room temperature and elevated temperatures, enabling uniform and smooth Li deposition. Thus, a long cycle life of solid-state Li symmetric cells for 1000 h at 60 °C is achieved, and stable cycling of solid-state Li metal full batteries at 60 °C and even 100 °C. Furthermore, the solid-state pouch cell using this SPE exhibits excellent performance reliably after bending. The study clearly indicates that simultaneously improving mechanical properties and conductivity is the indispensable path to the practical application of solid-state electrolytes.
Owing to high graphitization degree, polyacrylonitrile (PAN)-based high modulus carbon fiber (HMCF) can not only be used as the general structural reinforcement for advanced composites, but also be applied to improve the thermal conductivities (TC) of polymer composites . However, the enhancement of through-thickness TC of composites remains extremely challenging due to fiber anisotropy and the lack of continuous thermal conductive path among CFs. In the present work, three-dimensional (3D) hybrid thermal conductive structures were constructed onto PAN-CF surfaces to prepare HMCF/epoxy composites with high through-thickness TC. In details, crosslinked high thermal conductive Ni/CNT hybrid network was firstly electrodeposited onto HMCF surfaces, which also provided abundant channels for the impregnation of easily graphitized poly-p-phenylene benzobisoxazole (PBO)/graphene oxide (GO). The freeze-drying assisted grafting of 3D-oriented PBO/GO and high-temperature heat treatments were further conducted to create the 3D graphite structures onto CFs. The interconnected Ni/CNT networks with 500 nm thickness and 3D aligned PBO-graphite bridging structures with an average thickness of 1 μm contributed to the formation of efficient heat conduction pathways along the through-thickness direction. Additionally, high-temperature treatment had been proven critical to effective heat conductions. Especially, PAN-CF with the 3D hybrid thermal conductive structures treated at 2100 °C (named CNC@PG-2100) exhibited superior TC, and the maximum TC value of CNC@PG-2100 reinforced composites reached 5.39 W/(m‧K) at the CF loading of 55%, which improved by 573% compared to that of composites reinforced by untreated PAN-CFs (0.94 W/(m‧K)).
Traditional early fire warning systems struggle to meet the active protection demands of complex scenarios of environmental interference. Developing fire warning technologies with fast-response, self-powered, and intelligent interlocking capability has become an urgent priority to enhance safety protection levels. This study synthesized a hierarchical nanocomposite material based on thermoelectric Ag₂Se and polydopamine@carbon nanotubes (PDA@CNT). This composite was subsequently applied to the surface of mechanically strong and thermally stable Poly( p -phenylene benzobisoxazole) (PBO) fiber films to fabricate a dual-layer fire warning film. The output voltage of the composite film exhibited a strong linear relationship with temperature and can achieve over 100 cycles of repeatable fire warnings. The system can issue an fire warning signal within 1 s upon exposure to a heating stage at 200 °C. In combination with Halloysite nanotubes (HNTs), the hierarchical nanocomposite material was applied to the surface of a flammable wood to construct a flame-retardant-early-warning structure. The treated wood achieved UL-94 V0, and 45.5 % and 42.1 % reductions in the peak heat release rate (pHRR) and total heat release (THR), respectively., while retaining its sensitive fire warning functionality with an issuing signals within 4 s upon contact with a heating stage at 100 °C. By integrating Internet of Things (IoT) technology, a wireless intelligent thermoelectric response fire warning system with adjustable thresholds was developed, enabling rapid fire detection and real-time wireless transmission of fire warning signals. Voltage signals can be monitored in real-time via OLED displays and mobile devices, and the adjustable fire warning threshold voltage demonstrates flexibility in adapting to diverse application scenarios, showcasing the great potential for next-generation intelligent IoT-based fire warning applications.
危险品化学品经营许可证（带存储）