Abstract Review: efforts towards the realization of an artificial photosynthetic system able to convert sunlight into electricity using water as solvent; 328 refs.
The Cover Feature shows a modern building powered by aqueous solar cells, placed both indoors and outdoors. Transparency, colors, and safety: new ingredients for hybrid photovoltaics. The cover is designed by Barth van Rossum. More information can be found in the Full Paper by L. Fagiolari et al.
Poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) are among the most promising materials for solid-state lithium metal batteries (LMBs) due to their inherent safety advantages; however, they suffer from insufficient room-temperature ionic conductivity (up to 10–6 S cm–1) and limited oxidation stability (<4 V). In this study, a novel "polymer-in-high-concentrated ionic liquid (IL)" (PiHCIL) electrolyte composed of PEO, N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl) imide (C3mpyrFSI) IL, and LiFSI is designed. The EO/[Li/IL] ratio has been widely varied, and physical and electrochemical properties have been explored. The Li-coordination and solvation structure has been explored through Fourier-transform infrared spectroscopy and solid-state magic-angle spinning nuclear magnetic resonance. The newly designed electrolyte provides a promisingly high oxidative stability of 5.1 V and offers high ambient temperature ionic conductivity of 5.6 × 10–4 S cm–1 at 30 °C. Li|Li symmetric cell cycling shows very stable and reversible cycling of Li metal over 100 cycles and a smooth dendrite-free deposition morphology. All-solid-state cells using a composite lithium iron phosphate cathode exhibit promising cycling with 99.2% capacity retention at a C/5 rate over 100 cycles. Therefore, the novel approach of PiHCIL enables a new pathway to design high-performing SPEs for high-energy-density all-solid-state LMBs.
The modern life style that we are enjoying depends on energy storage systems in which the role of Li-ion batteries (LiBs) is peerless. However, state-of-the-art LiBs are approaching the verge of possible technological imagination in energy density. Some researchers argue that next-gen secondary batteries should switch to heavier elements such as Na. Indeed, when it comes to gigantic energy storage systems for the electricity grid and/or other non-portable applications where size does not matter, Na-ion batteries (NiB) can be an intelligent choice. Nevertheless, research on NiBs' components is at the very beginning, and it is necessary to develop novel types of materials, both novel high energy electrodes and stable and safe polymer electrolytes. In this work, an overview is provided on both truly solid and quasi-solid polymer electrolytes specifically conceived and developed for Na-ion secondary cells, based on polyethylene oxide (PEO), acrylates/methacrylates and/or mixtures thereof. Eventually, pyranose ring based natural additives and/or low volatile plasticizers are added along with supporting sodium salts to improve specifically defined characteristics. Both standard casting and smart photopolymerization techniques have been explored. Moreover, the most recent results regarding novel nanostructured negative electrodes, comprising TiO2 nanotubes, Ga2O3 nanorods and graphene-supported metal oxides will be presented. So far, work on Na-ion polymer batteries for moderate temperature application is at an early stage, only lab-scale small battery cells are demonstrated. The results about Ga2O3 nanorods and TiO2 nanotubes, along with the appropriate choice and development of novel polymer electrolytes, demonstrate that safe, durable and high energy density secondary Na-based polymer devices conceived for green-grid storage and operating at ambient and/or sub-ambient temperatures can be a reality in the near future
Modern life style depends on energy storage systems in which the role of Li-ion batteries (LiBs) is peerless. However, state-of-the-art LiBs are approaching the verge of possible technological imagination in energy density. Some researchers argue that next-gen secondary batteries should switch to heavier elements. Indeed, when it comes to energy storage systems for electricity grid, electric transportation or other non-portable applications, Na-ion (NiB) and Lithium Sulphur (Li-S) batteries can be an intelligent choice. These devices are still at an early stage of advancement and research must necessarily focus on the development of novel types of materials: safe polymer electrolytes, high-energy electrodes and novel production processes thereof. Here, an overview is provided on both solid/quasi-solid polymer electrolytes and nanostructured electrodes specifically conceived for NiB and Li-S secondary cells. Polymer electrolytes are based on polyethylene oxide (PEO), methacrylates and/or their mixtures; eventually, pyranose ring based natural additives and/or low volatile plasticizers are added along with supporting sodium salts to improve specifically defined characteristics. Both standard casting and smart free radical polymerization techniques are explored, thus producing multiphase electrode-electrolyte composites. In this process, an appropriate liquid reactive mixture comprising monomers, salts and eventually additives, which constitutes the polymer electrolyte precursor, is in-situ polymerised to form, in a single step, a self-standing electrode intimately connected to the ion conducting electrolyte membrane, with an efficient interpenetration of the two surfaces. Lab-scale Na-ion and Li-S polymer cells are assembled with different nanostructured electrode materials (e.g., LiFePO4, TiO2 nanotubes, sulphur-activated carbon) and tested for their long-term cycling ability and rate capability, demonstrating that safe, durable and high energy density post-lithium devices operating at ambient temperatures can be a reality in the near future.
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