Freestanding Macroporous Silicon and Pyrolyzed Polyacrylonitrile As a Composite Anode for Lithium Ion Batteries

Silicon continues to draw great interest as an anode material for lithium ion batteries due to its large specific capacity for lithium. Macroporous silicon produced by electrochemical etching is one of several anode materials of interest, but its energy density is oftentimes limited due to its attachment to an unreactive silicon substrate. Here, we present a novel “lift-off” method by which a freestanding macroporous silicon film (MPSF) is electrochemically detached from the underlying bulk silicon and combined with pyrolyzed polyacrylonitrile (PAN), a conductive polymer that forms a conjugated-chain chemical structure. We report the performance of these silicon thin films with and without pyrolyzed PAN.