An amorphous red phosphorus/carbon composite is obtained through a facile and simple ball milling process, and its electrochemical performance as an anode material for Na ion batteries is evaluated. The composite shows excellent electrochemical performance including a high specific capacity of 1890 mA h g(-1), negligible capacity fading over 30 cycles, an ideal redox potential (0.4 V vs. Na/Na(+)), and an excellent rate performance, thus making it a promising candidate for Na ion batteries.

No abstract

Sn4 P3 is introduced for the first time as an anode material for Na-ion batteries. Sn4 P3 delivers a high reversible capacity of 718 mA h g(-1), and shows very stable cycle performance with negligible capa-city fading over 100 cycles, which is attributed to the confinement effect of Sn nanocrystallites in the amorphous phosphorus matrix during cycling.

Electrochemical deposition of MnO2 onto carbon nanotube (CNT) yarn gives a high-performance, flexible yarn supercapacitor. The hybrid yarn's blended structure, resulting from trapping of MnO2 in its internal pores, effectively enlarges electrochemical area and reduces charge diffusion length. Accordingly, the yarn supercapacitor exhibits high values of capacitance, energy density, and average power density. Applications in wearable electronics can be envisaged.

Fiber and yarn supercapacitors that are elastomerically deformable without performance loss are sought for such applications as power sources for wearable electronics, micro-devices, and implantable medical devices. Previously reported yarn and fiber supercapacitors are expensive to fabricate, difficult to upscale, or non-stretchable, which limits possible use. The elastomeric electrodes of the present solid-state supercapacitors are made by using giant inserted twist to coil a nylon sewing thread that is helically wrapped with a carbon nanotube sheet, and then electrochemically depositing pseudocapacitive MnO2 nanofibers. These solid-state supercapacitors decrease capacitance by less than 15% when reversibly stretched by 150% in the fiber direction, and largely retain capacitance while being cyclically stretched during charge and discharge. The maximum linear and areal capacitances (based on active materials) and areal energy storage and power densities (based on overall supercapacitor dimensions) are high (5.4 mF/cm, 40.9 mF/cm2, 2.6 μWh/cm2 and 66.9 μW/cm2, respectively), despite the engineered superelasticity of the fiber supercapacitor. Retention of supercapacitor performance during large strain (50%) elastic deformation is demonstrated for supercapacitors incorporated into the wristband of a glove.

4,4′-Biphenyldicarboxylate sodium coordination compounds with different crystal structures are evaluated as anode materials for Na-ion batteries.

Lithium-oxygen (Li-O) batteries are desirable for electric vehicles because of their high energy density. Li dendrite growth and severe electrolyte decomposition on Li metal are, however, challenging issues for the practical application of these batteries. In this connection, an electrochemically active two-dimensional phosphorene-derived lithium phosphide is introduced as a Li metal protective layer, where the nanosized protective layer on Li metal suppresses electrolyte decomposition and Li dendrite growth. This suppression is attributed to thermodynamic properties of the electrochemically active lithium phosphide protective layer. The electrolyte decomposition is suppressed on the protective layer because the redox potential of lithium phosphide layer is higher than that of electrolyte decomposition. Li plating is thermodynamically unfavorable on lithium phosphide layers, which hinders Li dendrite growth during cycling. As a result, the nanosized lithium phosphide protective layer improves the cycle performance of Li symmetric cells and Li-O batteries with various electrolytes including lithium bis(trifluoromethanesulfonyl)imide in N,N-dimethylacetamide. A variety of ex situ analyses and theoretical calculations support these behaviors of the phosphorene-derived lithium phosphide protective layer.

Reduced graphene oxide nanoribbon fibers were fabricated by using an electrophoretic self-assembly method without the use of any polymer or surfactant. We report electrical and field emission properties of the fibers as a function of reduction degree. In particular, the thermally annealed fiber showed superior field emission performance with a low potential for field emission (0.7 V µm(-1)) and a giant field emission current density (400 A cm(-2)). Moreover, the fiber maintains a high current level of 300 A cm(-2) corresponding to 1 mA during long-term operation.