Negative electrodes based on regular structured porous silicon for lithium-ion batteries

Abstract

Silicon electrodes with regular porous structure were prepared by the photoelectrochemical etching of single-crystal n-type silicon wafers, followed by the removal of the substrate. Electrodes with pores having circular and square section were studied. The porosity was increased via additional oxidation with the subsequent etching of oxide. The electrochemical characteristics of anodes were found to depend on porosity, electrodes with porosity 60–70% possessing maximal capacity for lithium reversible insertion. Electrodes thus prepared feature much higher capacity per area unit (up to 25 mA⋅h/cm2) than usual thin-film electrodes (about 1 mA⋅h/cm2).