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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]

The severe volumetric changes occur during the lithiation/de-lithiation of silicon materials, which are the main cause of battery capacity failure. In this study, the expansion behavior of a cell composed of a silicon-carbon anode and Li(Ni 0.5 Co 0.2 Mn 0.3)O 2 (NCM523) was measured using the electrochemical dilatometry, and the contributions of different silicon and carbon components to the expansion were analyzed, along with factors affecting the cyclic stability of the silicon carbon anode. The results indicate that amorphous carbon can inhibit the volume expansion of monocrystalline silicon in the late stage of lithiation, thereby ensuring the cyclic stability of silicon. The cyclic stability of silicon-carbon composites is affected by irreversible expansion and expansion variation, and these two factors are negatively correlated. This research provides insights and guidance for the design of silicon carbon electrodes with superior electrochemical performance. • The impact of silicon-carbon components on cycle stability. • The depth of lithiation influences the expansion of the anode. • Amorphous carbon can effectively inhibit the expansion of silicon anode. • The change in expansion is negatively correlated with irreversible expansion. [ABSTRACT FROM AUTHOR]

Silicon-based anode materials have numerous advantages, including abundant reserves, high specific capacity, and environmental friendliness, which is an important direction for the development of anode materials in the future. However, the volume of silicon changes significantly during the processes of lithiation and de-lithiation, which limit its widespread use. In this study, silicon-carbon composites were prepared by using a high-temperature pyrolysis method. Among them, silicon was used as an active material, and phenolic resin served as the carbon source. Si@C showed better cycling stability and reversibility in constant current cycling tests compared silicon and graphite directly composites. Furthermore, according to the results of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), the addition of amorphous carbon can effectively reduce the electrode damage caused by volume expansion and the shrinkage of silicon materials, which has a positive effect on the stability of SEI. Additionally, the high conductivity of amorphous carbon improves the electrochemical kinetics of the battery during cycling, thereby enhancing the performance of silicon anodes. [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]

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]