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Silicon carbon nanoparticles (SCNPs) coated with reduced graphene oxide (rGO) were fabricated by a hydrothermal method and subsequently by a simple heat treatment process. SCNPs/rGO exhibit excellent electrochemical performance which not only attributes the rGO layer to inhibit the volumetric expansion of silicon and reduce the impedance between the active material and lithium ions during the electrochemical process, but also improves the electrical conductivity of SCNPs/rGO. The as-prepared compound was cyclically tested at a current density of 150 mA/g, with the first charge and discharge capacities of 3152.2 mAh/g and 3342.7 mAh/g, respectively. Moreover, the electrochemical performance of SCNPs/rGO was better than SCNPs. The R CT values for fresh battery, after 1 cycle and 100 cycles, are 120.9 Ω , 120.5 Ω and 104 Ω. Thus, compared with SCNPs, SCNPs/rGO exhibited lower overall impedance values. These results indicate that the addition of graphene layer significantly improved the electrochemical performance of SCNPs electrodes and reduced the internal resistance of the battery. Silicon carbon nanoparticles coated with rGO were obtained by hydrothermal method. The use of rGO to improve the electrical conductivity of the material can also act as a carbon matrix material to inhibit the volume expansion effect. The results showed that the addition of rGO improved the conductivity of lithium ions and played a positive role in the diffusion of lithium ions. [ABSTRACT FROM AUTHOR]

In this study, binder-free tungsten oxide carbon nanofibers and graphene oxide composites (WO3 CNFs/GO) were prepared as self-supporting anodes for lithium-ion batteries (LIBs) by applying a one-step electrostatic spinning technology. Owing to the combination of WO3 CNFs (WCF) and graphene oxide (GO), the composites exhibit excellent performance by suppressing expansion during the cycle. WO3 CNFs (WCF) provide excellent continuity and uniform width, and the GO adhered to the WCF forms a cross-linked conductive network and an internal mesoporous environment, which reduces the diffusion distance of electrons/ions and facilitates charge transfer. In addition, the disordered arrangement of WO3 CNFs (WCFs) can increase the porosity and increase the contact area with the electrolyte, which is more favorable for electrolyte penetration. The WO3 CNF/GO (WCFG) anode had a specific capacity of 644.6 mA h g−1 after 250 cycles. [ABSTRACT FROM AUTHOR]

SnS 2 nanosheet (NS), SnS 2 nanoflower (NF) and SnS 2 NF@reduced graphene oxide (rGO) were synthesized by hydrothermal method. When used as anode materials for lithium-ion batteries (LIBs), SnS 2 NF@rGO exhibits reversible specific capacities of 525 mAh/g at 0.5C after 360 cycles and 412.5 mAh/g at 2.0C, which are significantly enhanced Li storage performance over SnS 2 NS and SnS 2 NF. The detailed electrochemical impedance spectroscopy (EIS) analysis were found that SnS 2 NF@rGO nanocomposite exhibits much reduced internal resistance originated from the decreasing Warburg factor. The electronic conductivity of the cycled SnS 2 NF@rGO is about three times more than that of cycled SnS 2 NS and SnS 2 NF. More importantly, the Li+ diffusion coefficients D L i + were calculated using the galvanostatic intermittent titration technique (GITT) method, indicating SnS 2 NF@rGO demonstrated much enhanced Li+ diffusion kinetics than that of electrodes without rGO additives. This means that SnS 2 NF@rGO is more suitable to be applied as anode materials for LIBs because the electrochemical performance was enhanced by the improved ionic transport properties, resulting from the increased electronic conductivity by the addition of two-dimensional layer structure rGO with superior electronic conductivity. This study could help us understanding how electronic conductivity contributed to ionic transport kinetics in electrochemical energy storage and conversion (EESC). • SnS 2 NF@rGO nanocomposite was synthesized by hydrothermal method. • SnS 2 NF@rGO exhibits reduced internal resistance leads to improved electrochemical performance. • The rGO additives leads to improved Li+ diffusion kinetics of SnS 2 NF@rGO. [ABSTRACT FROM AUTHOR]