Pan Hui,Wang Lei,Shi Yu,Sheng Chuanchao,Yang Sixie,He Ping,Zhou Haoshen
Applying high stack pressure (often up to tens of megapascals) to solid-state Li-ion batteries is primarily done to address the issues of internal voids formation and subsequent Li-ion transport blockage within the solid electrode due to volume changes. Whereas, redundant pressurizing devices lower the energy density of batteries and raise the cost. Herein, a mechanical optimization strategy involving elastic electrolyte is proposed for SSBs operating without external pressurizing, but relying solely on the built-in pressure of cells. We combine soft-rigid dual monomer copolymer with deep eutectic mixture to design an elastic solid electrolyte, which exhibits not only high stretchability and deformation recovery capability but also high room-temperature Li-ion conductivity of 2×10 −3 S cm −1 and nonflammability. The micron-sized Si anode without additional stack pressure, paired with the elastic electrolyte, exhibits exceptional stability for 300 cycles with 90.8% capacity retention. Furthermore, the solid Li/elastic electrolyte/LiFePO 4 battery delivers 143.3 mAh g −1 after 400 cycles. Finally, the micron-sized Si/elastic electrolyte/LiFePO 4 full cell operates stably for 100 cycles in the absence of any additional pressure, maintaining a capacity retention rate of 98.3%. This significantly advances the practical applications of solid-state batteries.
Nowadays, electrolytes for commercial batteries are mostly liquid solutions composed of solvent and salt to migrate the ions. However, solvents of the electrolyte bring several inherent limitations, either the electrochemical window, working temperature, volatility or flammability. Herein, we report polyphosphoric acid as a solvent-free protic liquid electrolyte, which excludes the demerits of solvent and exhibits unprecedented superiorities, including nonflammability, wider electrochemical stability window (>2.5 V) than aqueous electrolyte, low volatility and wide working temperature range (>400 °C). The proton conductive electrolyte enables MoO 3 /LiVPO 4 F rocking-chair battery to operate well in a wide temperature range from 0 °C to 250 °C and deliver a high power density of 4975 W kg −1 at a high temperature of 100 °C. The solvent-free electrolyte could provide a viable route for the stable and safe batteries working under harsh conditions, opening up a route towards designing wide-temperature electrolytes.
Developing robust sponge-based materials with high oil capacity and excellent flame resistance for oil spill cleanup is significant. Herein, a highly hydrophobic composite sponge material for oil-water separation, containing a melamine-formaldehyde (MF) sponge substrate and zeolitic imidazolate framework-8 (ZIF-8) coating was fabricated through the simple amino-assisted in-situ growth of ZIF-8 onto the strut surface of MF sponge. The successful integration of MF sponge and ZIF-8 nanoparticles in one composite material was confirmed by scanning electron microscopy, X-ray diffraction and nitrogen sorption . The synergistic effect of the MF substrate and ZIF-8 coating significantly improved its flame resistance. Combining the advantage of the MF substrate and the hydrophobic ZIF-8 nanocrystals , the ZIF-8/MF composite sponge showed high porosity and good hydrophobicity with a water contact angle of 130°. A high adsorption capacity towards various oils was achieved in the range of 76–164 g g −1 . Besides, the ZIF-8/MF composite sponge exhibited excellent separation performance for light oil/heavy oil-water mixtures via adsorption and/or gravity-driven separation. In addition, owing to its compressibility and mechanical stability, the ZIF-8/MF composite sponge could be easily regenerated by a simple squeezing method and showed excellent recyclability for the oil adsorption. These features make the ZIF-8/MF composite sponge promising for highly efficient oil-water separation.
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