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Sulfur/nitrogen dual-doped graphene aerogels (SNGAs) with a unique porous network structure have been designed through a facile and versatile one-pot hydrothermal strategy. When employed as anode in LIBs, the SNGAs with nitrogen content of 1.50 wt.% and sulfur content of 15.11 wt.% exhibit superior cycle life and rate capability. For example, a high reversible capacity of 1109.8 mAh g −1 can be obtained after 400 cycles even at a high current density of 800 mA g −1 . It was discreetly demonstrated that the prominent improved performance of SNGAs can be mainly ascribed to the effect of dual-doping heteroatoms in cooperation with each other in to the graphene lattice as well as the porous nanostructure facilitating the mass transfer for both ions and electrons. Our conclusions illustrate that the strategy of dual-doped graphene aerogel may promote the potential application of graphene for high performance lithium ion batteries. [ABSTRACT FROM AUTHOR]

The SnO 2 anode materials with various nanoparticle sizes were successfully synthesized to study their size effects on lithium storage performance. The compositions, structures, particle sizes and morphologies of the as-prepared samples were characterized by X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM) and high resolution transmission electron microscopy (HRTEM) techniques. It was confirmed that the obtained nanomaterials via a facile reflux approach show smaller size than that of hydrothermal method. Using cyclic voltammograms, electrochemical impedance spectroscopy, and galvanostatical charge/discharge testing, the SnO 2 anodes with different nanoparticle sizes exhibit various electrochemical performance with lithium, originating from the enormous volume changes associated with the alloying and de-alloying processes. It was demonstrated that the anode material with smaller nanoparticle size performs much better lithium storage performance. [ABSTRACT FROM AUTHOR]

SnO 2 has attracted intense interest for use as an anode material for lithium ion batteries because of various advantages of the high theoretical capacity and low-cost. Unfortunately, SnO 2 anode material suffers from the huge volume change and poor electrical conductivity. In order to address these problems, in this work, SnO 2 /graphene aerogel composites have been successfully synthesized by a facile hydrothermal approach. 3-4 nm-sized SnO 2 nanoparticles are uniformly dispersed over graphene aerogels. Our results indicate that the hydrothermal reaction time highly affects the electrode performance of the anodes. The nanocomposite electrode with reaction time of 3 h shows increased electrochemical performance with high energy capacity, long cycle life, and superior rate capability. After 100 cycles, it can deliver a high discharge capacity of 662 mAh g −1 at 100 mA g −1 . At 500 mA g −1 , it can still yield a discharge capacity of 619.7 mAh g −1 after 723 cycles. The performance improvement can attribute to the graphene aerogel, which can suppress the aggregation of SnO 2 nanoparticles, enhance the conductivity of SnO 2 , and increase their structural stability during cycling. This study strongly demonstrates that the SnO 2 /graphene aerogel composite is a promising anode material building high performance lithium ion batteries. [ABSTRACT FROM AUTHOR]

Abstract Polycrystalline nickel ferrite (NiFe 2 O 4) thin films were fabricated by pulsed laser deposition (PLD) and coated with nanometer layer of lithium phosphorus oxynitride (LiPON) by radio frequency magnetron sputtering (RF sputtering). Physical characterizations demonstrated that NiFe 2 O 4 thin films were not destroyed by LiPON coating with 50 nm thickness. Discharge capacity of LiPON coated NiFe 2 O 4 thin film after 50 cycles at 5 μA cm−2 was 849 mAh g−1, much higher than the counterpart value of pristine NiFe 2 O 4 thin film (449 mAh g−1), while rate capability was also greatly enhanced. Ex situ TEM investigation confirmed the two-steps reaction mechanism between NiFe 2 O 4 and Li, which includes an irreversible decomposition reaction of NiFe 2 O 4 in the first discharge process and reversible reactions between NiO, Fe 2 O 3 and their nanosized metal particles afterward. The significant improvement on the electrochemical performance was ascribed to the amorphous LiPON layer on the surface, which suppressed the volume expansion of electrode, the formation of delaminated particles and generation of cracks on electrode surface, as proved by ex situ SEM and AFM results. The LiPON coating is an effective approach to enhance the electrochemical performance of conversion materials for lithium ion batteries. Highlights • Pristine and LiPON coated NiFe 2 O 4 thin films were fabricated. • LiPON coating benefits the electrochemical performance of NiFe 2 O 4 thin film. • Conversion mechanism was confirmed by ex situ TEM technique for the first time. • Ex situ SEM and AFM results explained the effect of LiPON coating. [ABSTRACT FROM AUTHOR]

Fe 2 SeS is successfully synthesized by facile solid-state reaction and the electrochemical investigation of Fe 2 SeS as anode for lithium ion batteries is reported for the first time. Fe 2 SeS deliverers a large initial discharge capacity of 471 mAh g −1 . The initial coulombic efficiency (92.56%) is higher than most of double-anion compounds reported previously. It is unexpected to find that Fe reacts simultaneously with Li 2 S and Li 2 Se to reform Fe 2 SeS during charging process, which is different from most double-anion compounds. [ABSTRACT FROM AUTHOR]

Three dimensional self-assembled graphene aerogel (GA) anode materials with some surface defects have been successfully generated through a facile hydrothermal procedure using graphene oxide as precursor. The morphologies and textural properties of as-obtained GA were investigated by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman and other spectroscopy techniques. The surface defects and electrical conductivities of GA can be controlled by adjusting the hydrothermal reaction time. The results indicate that GA with a reaction time of 6 h exhibits extremely high reversible capacity (1430 mAh g −1 at the current density of 100 mA g −1 ) and superior rate capability (587 mAh g −1 at 800 mA g −1 ) with excellent cycling stability (maintaining a reversible capacity of 960 mAh g −1 at 100 mA g −1 after 100 cycles). It is demonstrated that the 3D porous network with increased defect density, as well as the considerable electrical conductivity, results in the excellent electrochemical performance of the as-made GA anodes in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The nanoscale polycrystalline of solid electrolyte Li 3.2 Zr 0.4 Si 0.6 O 3.6 coating is used to enhance the electrochemical performances of LiNi 0.8 Co 0.15 Mn 0.05 O 2 (NCM) for lithium-ion batteries. [Display omitted] • NP-LZSO coating layer was quantitatively analyzed to study the impact of NCM. • NP-LZSO coated NCM was synthesized by simple chemical approach. • NP-LZSO coating approach remarkably improves the NCM cycling stability. • Phase transformation is effectively suppressed by NP-LZSO. As nickel-rich cathodes materials begin to attract immense attentions for its ultra-high capacity for Li-ion batteries (LIBs), their cycling stability remains insufficient for electric vehicles. Surface coating is regarded as an efficient approach in the enhancement of Ni-rich cathodes. Unfortunately, surface modification of cathode via a simple and effective way is still great challenges. Here we report a facile one-step chemical approach using nanoscale polycrystalline of solid electrolyte Li 3.2 Zr 0.4 Si 0.6 O 3.6 (NP-LZSO) to build a conductive protective coating on Ni-rich cathode LiNi 0.8 Co 0.15 Mn 0.05 O 2 (NCM). The NP-LZSO coating layer facilitates the transportation of Li-ions, significantly suppresses the undesired side reactions in cycling process, and effectively stabilizes the electrolyte-NCM interface. This approach remarkably improves the cycling stability with a capacity retention rate of 79.9% over 400 cycles at 0.2C. This effective strategy provides a new insight using nanoscale polycrystalline of solid electrolyte to modify surface of nickel-rich cathodes to improve its cyclic performance. [ABSTRACT FROM AUTHOR]