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Hard carbon was prepared via the carbonization of the old loofah sponge at 800 °C for 1 h in the inert N 2 atmosphere for sodium ion battery (SIB) anode. The resultant old-loofah-derived hard carbon was investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Raman, galvanostatic charge/discharge, cyclic voltammetry (CV) and alternating current (AC) impedance. The results suggested that the old-loofah-derived hard carbon powders consisted of many irregular micro-particles with the mean particle size of 12 μm. Furthermore, the old-loofah-derived hard carbon anode also delivered satisfactory electrochemical performances in SIB. For example, the initial discharge specific capacity was as high as about 695 mAh g −1 at 25 mA g −1 , and the reversible discharge specific capability after 1000 cycles was still about 171 mAh g −1 even at 1000 mA g −1 , indicating long cycle stability and the promising feasibility of the old-loofah-derived hard carbon anode. The disordered micro-structure and large interlayer distance may jointly contribute into the satisfactory electrochemical performances. [ABSTRACT FROM AUTHOR]

In this work, polypyrrole (PPy) was co-doped with l -lactic acid (LA) and sodium p -toluenesulfonate (TsONa) for high performance cathode in sodium ion battery (SIB) via facile one-step electropolymerization on Fe foil. The as-synthesized LA/TsONa co-doped PPy cathode was investigated in terms of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), galvanostatic charge/discharge and cyclic voltammetry (CV). The results suggested that some oval-bud-like LA/TsONa co-doped PPy particles did form and tightly combine with the surface of Fe foil; furthermore, LA/TsONa co-doped PPy cathode also delivered higher electrochemical performances than TsONa mono-doped PPy cathode. For example, the initial specific discharge capacity was as high as about 124 mAh/g, and the reversible specific capacity still maintained at about 110 mAh/g even after 50 cycles, higher than those of TsONa mono-doped PPy cathode. The synergy effect of multi components of LA/TsONa co-doped PPy cathode should be responsible for high electrochemical performances. [ABSTRACT FROM AUTHOR]

Composite sodium p-toluenesulfonate/polypyrrole/TiO 2 nanotubes/Ti was designed and synthesized for sodium ion battery anode via facile electrochemical methods. The obtained composite sodium p-toluenesulfonate/polypyrrole/TiO 2 nanotubes/Ti (TsONa/PPy/TiO 2 NT/Ti) electrode was investigated in terms of SEM, EDX, FTIR, galvanostatic charge/discharge and AC impedance. As expected, the composite TsONa/PPy/TiO 2 NT/Ti electrode displayed higher electrochemical performances than the bare TiO 2 NT/Ti electrode. For example, the reversible capacity after 50 cycles was still as high as about 200 mAh/g, higher than 170 mAh/g of TiO 2 NT/Ti electrode. High Na-storage activities of both TiO 2 NT and TsONa/PPy, high conductivity of TsONa-doped PPy and the synergy effect among the various components may be responsible for the improved electrochemical performances. [ABSTRACT FROM AUTHOR]