A conceptually new defect-free principle is proposed for designing graphene cathode of aluminum-ion battery: the fewer the defects, the better the performances. Developed through scalable approach, defect-free graphene aerogel cathode affords high capacity of 100 mAh g under an ultrahigh rate of 500 C, exceeding defective graphene and previous reports. This defect-free principle can guide us to fabricate better graphene-based electrodes.

provide an incessant highway for electron transportation, further reducing the electrochemical polarization. The large theoretical specific surface area [13] (2630 m 2 g −1 ) and unstuck graphene surface contribute to better loading and distribution of nanosized active materials. In addition, the remarkable mechanical properties of graphene [14] can preserve the integrity of electrode in the volume expansion/ shrink process during battery operation. [7] Nevertheless, it is worth mentioning that these supreme properties are only achieved in the highest quality graphene: a single-layer, defect-free graphene sheet as large as possible. Hence, improving the quality of graphene, especially three major parameters of defect concentration, stacking degree, and lateral size of graphene sheets, is of crucial importance. [2] Actually, the large-scale production of high-quality graphene has been generally regarded as the most ambitious challenge to address before practical application of graphene materials. [1,2,15] In this respect, chemical exfoliation of graphite especially oxidation into graphene oxide (GO), has been commercialized, and large size single-layer GO can be produced in ton-level scale with relatively low cost. [16,17] GO is generally reduced into chemically converted graphene (CCG) for further applications in electrodes. However, CCG still contains abundant defects, greatly limiting the vital electric conductivity and other properties. Hence, reducing the defect concentration is the basic concern for real applications of GO and CCG in EES technologies. [1,2,13] Even though methods such as heteroatom doping, [18] chemical vapor deposition, [19] and deliberate design of microsized morphology [7,20] have been utilized to improve electrochemical properties of graphene-based materials, respectively, [21][22][23] whereas their productivity, precise controllability, high reproducibility, and compatibility with the industrial cast-coating technology (particularly for those monolithic graphene bulks) are challenges hard to be resolved. Therefore, it is urgent to find a new production method of graphene, especially powder-formed graphene material that accords with requirements in both quality and quantity to satisfy the demands from EES applications.Here, we propose a new facile and highly controllable strategy to produce high-quality graphene powder, that is, crumpled graphene microflower (GmF), in large scale. Through our design, three parameters of high-quality graphene are simultaneously achieved in GmF: (i) raw materials of ultralarge Poor quality and insufficient productivity are two main obstacles for the practical application of graphene in electrochemical energy storage. Here, highquality crumpled graphene microflower (GmF) for high-performance electrodes is designed. The GmF possesses four advantages simultaneously: highly crystallized defect-free graphene layers, low stacking degree, sub-millimeter continuous surface, and large productivity with low cost. When utilized as carbon host for sulfur cathode, the ...

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Silver/polyvinyl alcohol (Ag-PVA) nanocomposite films have been prepared via in situ generation of silver nanoparticles (Ag NPs) by the respective metallic salts and dispersion of preformed Ag NPs (ex situ synthesis) inside polyvinyl alcohol (PVA) and its effect of sensing towards a model protein (bovine serum albumin-BSA) was investigated. The influence of Ag NPs, irrespective of their reduction methodology on the optical and the thermal properties of the PVA, had been investigated using UV-Vis spectrophotometer and differential scanning calorimetry. The absorption peak around 400 nm indicates the surface plasmon resonance response of Ag NPs. The interaction of the dispersed and preformed Ag NPs with the PVA chains is confirmed by the corresponding vibrational signatures of the PVA through Fourier transform infrared spectroscopy (FTIR). The changes in the glass transition and melting temperatures (T g and T m ) of the pure PVA upon the presence of Ag NPs are reported using differential scanning calorimeter (DSC). The sizes of the synthesized Ag NPs are found to be in the range of 200 ± 10 nm for in situ reduction of silver nitrate (AgNO 3 ) and 100 ± 10 nm for the external addition of preformed Ag NPs by sodium borohydride (NaBH 4 ) reduction using scanning electron microscopy (SEM).