Developers Create Silicon “Sponge” Anode for Lithium-Ion Batteries

Researchers at Rice University and the Lockheed Martin Advanced Nanotechnology Center have discovered a process to grow honeycomb-like silicon structures that could be used to make higher-performance anodes for electric car batteries.

The developers say the spongy material can store more than four times its weight in lithium in pores that measure one micron wide and 50 microns deep. The team previously showed that the material could hold 10 times as much lithium as graphite can.

Group leaders Madhuri Thakur and Sibani Lisa Biswal say they have been able to grow at least four silicon sponges from a single standard 250-micron-thick silicon wafer. The electrochemical etching process used to create the pores also separates the sponge from the substrate.

After removing the spongy material, Thakur and Biswal enhanced the its conductivity by soaking it in a conductive polymer binder (pyrolyzed polyacrylonitrile). Then they attached the material to an electric current collector and used it to build a lithium-ion battery. The resulting system has a discharge capacity of 1,260 milliamp-hours per gram.

The researchers report their work in the American Chemical Society's online journal, Chemistry of Materials, that can be downloaded HERE.