Abstract
Coral-like porous Si was fabricated through the dealloying of a laser remelted as-cast AlSi12 alloy(Al-12 wt % Si). The porous Si was composed of interconnected micro-sized Si dendrites and micro/nanopores, and compared to flaky Si, which is fabricated by direct dealloying of the as-cast AlSi12 alloy. The structure of the porous Si was attributed to the dendritic solidification microstructure formed during the laser remelting process. The micropore size of the porous Si decreased from 4.2 μm to 1.6 µm with the increase in laser scanning velocity, indicating that the morphology of porous Si could be easily altered by simply controlling the laser remelting parameters. The coral-like porous Si provided enough space, making it promising for high-performance Si-based composite anode materials in lithium-ion batteries. The proposed hybrid method provides a straightforward way of tuning the porous structure in the dealloyed material.
Highlights
Silicon (Si) is regarded as the most promising anode material for high-performance lithium-ion batteries (LIBs) owing to its outstanding volumetric/gravimetric capacity and abundance [1,2,3].the use of bulk Si is impeded by the well-known pulverization of Si due to inhomogeneous volume expansion (~300%) during lithiation and delithiation cycles [4,5,6].To address this problem, one successful method is to fabricate micro-sized porous Si–C composites by coating carbon onto micro-sized porous Si [7]
No clear phase transformation happened during the laser remelting process
Coral-like porous Si with a tunable morphology was achieved by a hybrid
Summary
Silicon (Si) is regarded as the most promising anode material for high-performance lithium-ion batteries (LIBs) owing to its outstanding volumetric/gravimetric capacity and abundance [1,2,3]. The use of bulk Si is impeded by the well-known pulverization of Si due to inhomogeneous volume expansion (~300%) during lithiation and delithiation cycles [4,5,6] To address this problem, one successful method is to fabricate micro-sized porous Si–C composites by coating carbon onto micro-sized porous Si [7]. The enhanced electrochemical performance is attributed to the following factors: (a) the micro-sized porous Si takes advantages of both high volumetric/gravimetric capacity of micro-Si and adequate space provided by the inside pore for Si volume expansion; and (b) the electrical contact and stability is improved by the carbon coating. Bang et al [19] showed that morphologies of the as-synthesized porous Si could be tuned by controlling the etching conditions.
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