High-areal capacity Si architecture as an on-chip anode for lithium-ion batteries

Silicon is one of the most promising anode materials for Li-ion batteries, especially to meet the growing demand for energy storage in the form of microbatteries for mobile and autonomous devices. However, the development of such batteries is hindered by mechanical and electrochemical failures resulting from massive Si volume expansion and continuous growth of the solid electrolyte interphase. In this study, we propose a novel on-chip anode architecture using rapid thermal annealing on porous silicon. The structure consists of a densified silicon layer on top of an isotropic structure of a porous layer. We demonstrate that this structure enhances both electrochemical and mechanical stabilities, achieving an areal capacity of 9 mAh cm−2 over more than 200 cycles with a high Coulombic efficiency near 100%.