Dealloying of modified Al-Si alloy to prepare porous silicon as Lithium-ion battery anode material

Silicon plays an important role in the development of high-energy Lithium-ion batteries. However, the high volume expansion rate (>300%) makes it a commercially unfeasible independent Lithium-ion battery anode material. In this work, we adopt P and Sr complex modification and increase the cooling rate to refine the microstructure of Casting Al-20Si alloy, then acid etching Al-20Si alloy ingot to prepare porous silicon. The as-prepared silicon has a three-dimensional dendritic porous structure based on the SEM morphology characterization. The porous silicon electrode was prepared with Si powder: acetylene black: binder in a ratio of 2:1:1. The electrolyte solution was 1 M LiPF6/EC:EMC: DMC = 1:1:1 (V/V) with or without 5% FEC. In the electrolyte solution without 5% FEC, the first charge and discharge capacities of the porous silicon electrode are 2924.8 mAh/g and 1910.1 mAh/g, and the coulombic efficiency is about 65.31%. In the electrolyte solution with additive 5% FEC, the first charge and discharge capacities are 3444.6 mAh/g and 2469.5 mAh/g, respectively. Its first cycle coulombic efficiency is 72.19%. After adding 5% FEC into the electrolyte, the main component of SEI film is the decomposition product of FEC, which can effectively inhibit the decomposition of electrolyte solvent at a low potential and improve the specific capacity of the battery.

Automated summary

In this study, porous silicon electrode was prepared by adopting P and Sr complex modification and increasing the cooling rate. The porous silicon exhibited a three-dimensional dendritic porous structure based on SEM characterization. The addition of 5% FEC in the electrolyte solution significantly improved the charge-discharge performance of the porous silicon electrode.