Conventional vapor–liquid–solid mechanism of nanowire growth opens up new opportunities of fabricating nanowires with controllable morphologies and aspect ratios. However, gaseous precursors have disadvantages of high material and processing cost, high toxicity, and limited scalability. By contrast, synthesizing nanowires via solid–liquid–solid mechanism could be
a facile alternative since the low cost and nontoxic solid precursor is adopted in the process. In this study, the cooling control is found to be very critical for the solid–liquid–solid nanowire growth. Without a sufficient negative vertical temperature gradient, the nucleation and continuous growth of silicon nanowires could not occur. High volume gas flow cooling, fluctuating the heating temperature, decreasing the cooling rate, and applying a heat sink are all efficacious to promote silicon nanowire formation. In addition to the nanowires formed under high gas flow cooling on the silicon wafer sputtered with a nickel thin film, the solid–liquid–solid mechanism-derived silicon nanowire growth can also be economically achieved by adopting a solution-based coating of a nickel precursor onto the silicon substrate paired with a programmed slow cooling condition without using any gas, which could be transferred to other eutectic systems for cost-effective nanomaterial fabrication.
This paper received an invitation to be featured as "Front Cover".
A low-level metallic lithium thermal prelithiation strategy has been developed for boosting the performance of SiO anode materials with aqueous slurry processability. This facile prelithiation method can alter the phase and crystalline size of lithium silicates by controlling the parameters such as lithium contents and processing temperatures. The prelithiated graphene-SiO composite anode material thus obtained under the optimized condition offers a high reversible capacity of 1062 mAh g−1 and the initial Coulombic efficiency of 80.8 %. Additionally, both the cycle life and cycling Coulombic efficiency are extremely stable, preserving over 90.3 % of the capacity after 200 cycles and more than 99.7 % of the efficiency on average during cycling. The significantly enhanced battery performance of the prelithiated SiO anode materials is owing to the size control of crystal silicon and Li2SiO3 phases. The existence of Li2Si2O5 and suppression of Li4SiO4 formation also guarantee homogeneous prelithiation results. This facile low-level prelithiation approach is remarkably effective to improve the initial Coulombic efficiency for commercial SiO anode materials and simultaneously maintain superior reversible capacity, cycle life, cycling efficiency, and aqueous slurry processability.
Update: This paper was highlighted as "Feature Paper" and "Editor's Choice".
To maximize the performance of energy storage systems more effectively, modern batteries/supercapacitors not only require high energy density but also need to be fully recharged within a short time or capable of high-power discharge for electric vehicles and power applications. Thus, how to improve the rate capability of batteries or supercapacitors is a very important direction of research and engineering. Making low-tortuous structures is an efficient means to boost power density without replacing materials or sacrificing energy density. In recent years, numerous manufacturing methods have been developed to prepare low-tortuous configurations for fast ion transportation, leading to impressive high-rate electrochemical performance. This review paper summarizes several smart manufacturing processes for making well-aligned 3D microstructures for batteries and supercapacitors. These techniques can also be adopted in other advanced fields that require sophisticated structural control to achieve superior properties.