Metallurgy of aluminum-inspired formation of aluminosilicate-coated nanosilicon for lithium-ion battery anode

摘要

Modification of Si anode with various coating matrixes is a promising strategy to resolve the unsta-ble solid electrolyte interphase issues.However,the com-plex preparation process and inherently weak interaction between Si and other matrixes impede its practical appli-cation.Inspired by the metallurgical process of aluminum,an aluminosilicate matrix was prepared as coating layer on the surface of Si nanoparticles after heat treatment.Si nanoparticles with a uniform native oxide layer were used as seed crystals for the adsorption of aluminum hydroxide.The strong symbiosis and bond between alumina and silica,such as mullite(3Al_(2)O_(3)·2SiO_(2))or kaolin(Al2O_(3)·SiO_(2)·2H_(2)O),provide homogeneous and durable contact coating layer.The as-produced Si/SiO_(2)·Al_(2)O_(3)composite delivers a charge capacity of 1440 mAh·g^(-1)at 100 mA·g^(-1)and remains 879 mAh·g^(-1)at 3 A·g^(-1).After 200 cycles,the capacity retention remains high at 76%.The enhanced properties were ascribed to SiO_(2)·Al_(2)O_(3)syner-gistic composite coating layer,which could hinder the interfacial side chemical reaction and buffer volume change of Si.