Improving the Rate and Cycle Performances of Porous Silicon Particles Prepared by Acid Etching of Al–Si Alloy Powders for Application in Lithium-Ion Batteries

Abstract

Silicon is considered an attractive active anode material for lithium-ion batteries because of its high theoretical capacity and abundance. However, the application of silicon anodes is hindered by their large volume changes during charge–discharge cycles and low conductivity. Herein, structural design is focused and a scalable method is developed for producing porous Si electrodes with excellent electrochemical characteristics and cycle properties. Al72.5Si25Ti2.5 powders with fine solidification structures are produced using the gas atomization method, and porous Ti(Al,Si)2@Si particles with uniform silicon frameworks are synthesized by leaching Al in the atomized powder precursor using hydrochloric acid. The porous Ti(Al,Si)2@Si particles show a pore size distribution of 50–200 nm and demonstrate excellent rate characteristics with a capacity of 1683 mAh g−1 after 100 cycles, a Coulombic efficiency of >97%, and high stability. The particles maintain discharge capacity at a constant charge capacity of 1000 mAh g−1 at 0.2 C for up to 1000 cycles without degradation. The pores elicit a buffer effect that suppresses volume expansion during lithium insertion while the Ti(Al,Si)2 silicide phase improves the electrical conductivity, improving rate and cycle performances.