Learning from solar cell processing to boost lithium ion battery performance
GmbH (RENA) develops a new inline system for porous silicon etching and starts cooperation with Christian Albrecht University in Kiel (CAU) to develop a simple manufacturing concept for silicon anodes for use in lithium ion batteries. Further potential application for photovoltaics.
Today’s lithium ion batteries typically rely on anodes made of graphite. The limited ability of the material to store lithium ions however restricts the energy density of such system s. Silicon can take up much more lithium ions and offers a theoretical specific energy density ten times higher than graphite, thus making it an appealing alternative approach. The problem: Silicon expands strongly when loaded with lithium ions which typic ally leads to cracking and destruction of the anode within a few cycles.
Researchers at the Kiel University have overcome this limitation by structuring the silicon in an electrochemical etching step. “The voids within the structure allow for the expansi on of the silicon and avoid mechanical fracture of the material”, explains Sandra Hansen, researcher at the Kiel University who published outstanding results with th is technology. However, the current etching process is not appropriate for mass – production scale – up because it typically requires a sealing on the processed substrate to avoid short currents between the positive and negative electrodes. This makes automation of the process demanding and its use almost impossible for applications with a high thro ughput such as lithium ion batteries.