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Hexagonal NiS nanobelts served as novel cathode materials for rechargeable Al-ion batteries based on an AlCl3/[EMIm]Cl ionic liquid electrolyte system. The nano-banded structure of the materials can facilitate the electrolyte immersion and enhance Al(3+) diffusion. The hexagonal NiS nanobelt based cathodes exhibit high storage capacity, good cyclability and low overpotential.

With the growing demands for large-scale applications, rechargeable batteries with cost-effective and environmental-friendly characteristics have gained much attention in recent years. However, some practical challenges still exist in getting ideal electrode materials. In this work, three-dimensional FeWO 4 /graphene mesoporous composites with incredibly tiny nanospheres of 5−15 nm in diameter have been synthesized by an in situ self-assembled hydrothermal route. First-principles density functional theory has been used to theoretically investigate the crystal structure change and the insertion/ extraction mechanism of Li and Na ions. Unlike most graphene-coated materials, which suffer the restacking of graphene layers and experience significant irreversible capacity losses during charge and discharge process, the as-prepared composites have alleviated this issue by incorporating tiny solid nanospheres into the graphene layers to reduce the restacking degree. High capacity and excellent cyclic stability have been achieved for both Li-ion and Na-ion batteries. At the current density of 100 mA g −1 , the discharge capacity for Li-ion batteries remains as high as 597 mAh g −1 after 100 cycles. The Na-ion batteries also exhibit good electrochemical performance with a capacity of 377 mAh g −1 at 20 mA g −1 over 50 cycles. The synthetic procedure is simple, cost-effective and scalable for mass production, representing a step further toward the realization of sustainable batteries for efficient stationary energy storage. ■ INTRODUCTIONDue to energy demand and the rapid growth in the price of fossil fuels as well as environmental problems, renewable energy sources will be of vital importance. 1−3 The development of rechargeable batteries as energy storage devices has gained much attention in recent years. 4−8 Among the various available energy storage technologies, lithium-ion batteries, with high energy and power densities, have been widely used in portable electric vehicles and electric power storage devices. 9−12 As the smallest (effective radius) metal ion, lithium is an ideal ionic guest for transferring electronic charges into different insertion hosts. However, there is a serious concern about the availability of lithium for the limit of lithium reserves in the earth, especially in large-scale applications. 13−15 Owing to the low cost and natural abundance of sodium and magnesium, recent research is focusing on rechargeable Na-based and Mg-based batteries as potential alternatives to lithium-ion batteries for electric energy storage. 16−18 Most recently, the eco-friendly Naion batteries operable at room temperature have received growing interest spurred by the rapid advances in rechargeable battery technology and fast increasing demand in the market. 19−24 However, the radius of Na ions is 55% larger than Li ions, making it more difficult for them to be reversibly inserted into and extracted from host materials. In consideration of the aforementioned reason, among various electrode materials for Li-ion batteries, o...

Polythiophene (PTh) was electrochemically polymerized onto the multiwalled carbon nanotube (MWCNT) modified carbon paper by a galvanostatic method in an oil-in-ionic liquid microemulsion (O/IL). The asprepared PTh/MWCNT composite had an interlaced framework morphology, in which the MWCNTs were uniformly coated by PTh with a thickness of 2-3 nm. The capacitive performance of the asprepared PTh/MWCNT composite was tested in 1 mol L À1 Na 2 SO 4 solution. The results showed that the composite film had a favorable capacitance with a high electron transfer rate and low resistance. The highest specific capacitance could be achieved as high as 216 F g À1 with the charge loading of 300 mC at a current density of 1 A g À1 . The PTh/MWCNT composite had a good cycle stability with a low fading rate of specific capacitance after 500 cycles. The results demonstrated the feasibility of the as-prepared PTh/MWCNT composite to be used as an electrode material for supercapacitors.

Lithium phosphorus oxynitride (LiPON) thin films as solid electrolytes were prepared by radio frequency magnetron sputtering of a Li 3 PO 4 target in ambient nitrogen atmosphere. The influence of radio frequency (rf) power on the structure and the ionic conductivity of LiPON thin films has been investigated. The morphology, composition, structure and ionic conductivity of thin films were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and a.c. impedance measurement. It was found that ionic conductivity of LiPON thin films increases with N content in thin films. XPS measurements reveal that ionic conductivity also keeps relativity with the structure of thin films. Higher the N t /N d ratio, higher will be the ionic conductivity of LiPON thin films. And both of them can be improved by increasing rf power from 1⋅5 W/cm 2 to 5⋅5 W/cm 2 .