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The electrochemical properties of an electrode material based on a high-capacity silicon/reduced graphene oxide composite are studied. It was determined that the optimal potentials for reversible insertion/extraction of lithium are in the range of 50–2000 mV. The discharge capacity is 980 mAh g–1 at the charge rate 0.3 C and discharge rate 1.0 C. The addition of vinylene carbonate to the electrolyte solution leads to the stabilization of the solid electrolyte layer on the electrode surface. The discharge capacity is 866 mAh g–1 at the 170th charge/discharge cycle. [ABSTRACT FROM AUTHOR]

Recently, the application of energy storage systems and electric vehicles has increased the importance of lithium-ion batteries (LIBs). However, despite their rising significance, the ability to increase their capacity through power generation of the anode is limited. In this study, we developed an LIB anode material made of silicon (Si) nanoparticle-embedded carbon-nanofiber web film (SNE-CWF) that showed excellent cycling performance when low current activation was performed. Further, we examined the electrochemical properties of SNE-CWF electrodes fabricated through our process as anodes in LIB. The capacity of Si embedded carbon nanofiber showed high specific capacity at 1001–1557 mAh/g at low current density of 20 mA/g than carbon nanofiber (initial capacity of 604 mAh/g). After activation with low current density, the 5 wt% SNE-CWF electrode provided a capacity of 870 mAh/g even when the current was increased to 200 mA/g, and capacity retention at 20th cycle was 92.7%, showing the most stable performance out of all the materials tested. Hence, the stability of performance in LIB was enhanced. The low current electrochemical activation method of SNE-CWF presented through this experiment is expected to suggest a new approach for the manufacture of next-generation electrode material for LIBs. [ABSTRACT FROM AUTHOR]

Silicon-based photovoltaic technology is helpful in reducing the cost of power generation; however, it suffers from economic losses and environmental pollution caused by silicon cutting waste. Herein, a hydrothermal method accompanied by heat treatment is proposed to take full advantage of the photovoltaic silicon cutting waste and biomass excrementum bombycis to fabricate flake-like porous Si@C (FP-Si@C) composite anodes for lithium-ion batteries (LIBs). The resulting FP-Si@C composite with a meso-macroporous structure can buffer the severe volume changes and facilitate electrolyte penetration. Meanwhile, the slightly graphitic carbon with high electrical conductivity and mechanical strength tightly surrounds the Si nanoflakes, which not only contributes to the ion/electron transport but also maintains the electrode structural integrity during the repeated lithiation/delithiation process. Accordingly, the synergistic effect of the unique structure of FP-Si@C composite contributes to a high discharge specific capacity of 1322 mAh g−1 at 0.1 A g−1, superior cycle stability with a capacity retention of 70.8% after 100 cycles, and excellent rate performance with a reversible capacity of 406 mAh g−1 at 1.0 A g−1. This work provides an easy and cost-effective approach to achieving the high-value application of photovoltaic silicon cutting waste, as well as obtaining high-performance Si-based anodes for LIBs. [ABSTRACT FROM AUTHOR]

In this study, we propose a mass production-able and low-cost method to fabricate the anodes of Li-ion battery. Carbonaceous anodes, integrated with thin amorphous silicon layers by plasma enhanced chemical vapor deposition, can improve the performance of specific capacity and coulombic efficiency for Li-ion battery. Three different thicknesses of a-Si layers (320, 640, and 960 nm), less than 0.1 wt% of anode electrode, were deposited on carbonaceous electrodes at low temperature 200◦C. Around 30 mg of a-Si by plasma enhanced chemical vapor deposition (PECVD) can improve the specific capacity ~42%, and keep coulombic efficiency of the half Li-ion cells higher than 85% after first cycle charge-discharge test. For the thirty cyclic performance and rate capability, capacitance retention can maintain above 96%. The thicker a-Si layers on carbon anodes, the better electrochemical performance of anodes with silicon-carbon composites we get. The traditional carbonaceous electrodes can be deposited a-Si layers easily by plasma enhanced chemical vapor deposition, which is a method with high potential for industrialization. [ABSTRACT FROM AUTHOR]

Influence exerted by the temperature of annealing in the atmosphere of argon on the ability of Si‒C nanocomposites to enable a reversible introduction of lithium has been studied. It was found that the higher the annealing temperature in the formation of a composite, the lower the capacity of the electrode fabricated from this composite. X-ray diffraction analysis and scanning electron microscopy demonstrated that the capacity decreases because silicon carbide of cubic modification β-SiC inactive toward formation of lithium alloys or intercalates is formed at T ≥ 1100°C. [ABSTRACT FROM AUTHOR]

Silicon-carbon composites are considered as the most promising anode materials for lithium ion batteries. Currently, most silicon-carbon composites were prepared by solid nano‑silicon particles as the silicon source, which suffers from high price and uneven dispersion. Here, we used tetraethyl orthosilicate as the liquid silicon source and polyvinylpyrrolidone as the carbon source. Both were homogeneously mixed in the liquid phase, and then processed through electrospinning, carbonization and nitrogen-doped processes to obtain free-standing nitrogen-doped carbon coated silicon monoxide (N-doped C/SiO x). When served as anode material, N-doped C/SiO x can possess a reversible capacity of 488 mAh g −1 at 0.5 C (0.6 A g −1) and 377 mAh g −1 at a high current density of 2 C (2.4 A g −1). In addition, copper foil is not used as a collector for free-standing electrode structure, and eliminates the coating process of traditional electrodes, which reduces production costs. It is proposed that a facile strategy to fabricate silicon-carbon composites with good electrochemical properties and cost-effective way for lithium ion batteries. [ABSTRACT FROM AUTHOR]

The studies of fundamentally new electrochemical systems for lithium-ion batteries of new generation, which were performed at the Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, are briefly reviewed. The results of investigation of lithium insertion into negative electrodes based on silicon and silicon-carbon composites and operation of positive electrodes of nano-structured materials based on vanadium oxides are described. [ABSTRACT FROM AUTHOR]

Silicon/carbon (Si/C) composites have become the mainstream anodes for silicon-based lithium-ion batteries (LIBs) with outstanding stability and high capacity, in which carbon can significantly stabilize the silicon anodes. Currently, most Si/C composites use nano‑silicon as raw materials, which suffer from low energy density, high price and preparation complexity. Here, we have developed a silicon-graphite‑carbon ternary composite (Si-G-C-15) with cheap micron-sized silicon as raw materials. It was prepared by ball-milling of micron silicon and graphite and subsequent carbonization of PAN, followed by NaOH selective etching. Electrochemical test results demonstrate that Si-G-C-15 can possess a reversible capacity of 965 mAh/g at 200 mA/g, with a capacity retention of 71.34% and 786 mAh/g at a high current density of 1 A/g after 100 cycles. Notably, this facile preparation process of silicon anodes with high rates and good capacity stability highlights the potential practical application. [Display omitted] • A facile routine is developed to fabricate silicon-graphite-carbon ternary composite. • Silicon anode using micro-sized silicon is low-cost and has high energy density. • NaOH etching method is powerful to improve electrode cycling stability and rate capability. [ABSTRACT FROM AUTHOR]

Silicon can be used in a variety of applications. Particularly, silicon particles are attracting increased attention as energy storage materials for lithium-ion batteries. However, silicon has a limited cycling performance owing to its peeling from the current collector and the volume expansion that occurs during alloying with lithium in the charging process. Significant contributors to this problem are the even distribution of silicon nanoparticles within the carbon matrix and their deep placement in the internal structure. In this study, we synthesized silicon nanoparticles and carbon materials via a bottom-up approach using a new method called plasma in solution. Silicon nanoparticles and the carbon matrix were synthesized in a structure similar to carbon black. It was confirmed that the silicon particles were evenly distributed in the carbon matrix. In addition, the evaluation of the electrochemical performance of the silicon–carbon matrix (Si–C) composite material showed that it exhibited stable cycling performance with high reversible capacity. [ABSTRACT FROM AUTHOR]