关键词: 锂离子电池, 多孔硅, 硅电极, 铝硅合金, 氟化碳酸乙烯酯

Abstract: Porous silicon powders prepared by etching Al-Si alloy using an acid solution was reported in the first time. The morphology and structure of as-obtained material were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) method. It was found that the spongy porous silicon powders presented well crystalline structure and consisted of nano-Si particles. The particle size of porous Si powders was about 20 μm, and the specific surface area was 102.7 m²·g^-1. The electrochemical properties of porous silicon powders were evaluated as an anode material for lithium ion batteries. The material proportion in the porous silicon electrode was porous Si:conducting C:binder = 1:1:1. It was measured that in 1 LiPF₆ mol·L^-1, EC:DMC = 1:1 + 15%(by mass)FEC electrolyte, the first discharge capacity of porous silicon electrode was 2072 mAh·g^-1 Si, and the capacity of 1431 mAh·g^-1 Si was kept after 237 cycles at the charge and discharge current densities of 100 mA·g^-1. Such high electrochemical performance of porous silicon electrode could be attributed to the spongy porous structure, which provided enough tiny space to buffer the huge volume variation of Si anode during charging/discharging process. The nano-size of Si particles was benefited to the diffusion process of lithium in Li-Si alloy, and the firm connection between Si nanoparticles could prevent the breakage of porous Si particles. This advanced method for producing high performance porous Si powders is simple and low cost, and has a bright prospect for the practical application

Key words: lithium-ion batteries, porous silicon, silicon electrode, Al-Si alloy, fluoroethylene carbonate