Longer lifetimes, larger ranges and faster recharging—developments such as electric mobility or the miniaturization of electronics require new storage materials for batteries. With its enormous storage capacity, silicon would potentially have decisive advantages over the materials used in commercial available lithium-ion batteries. But due to its mechanical instability, it has so far been almost impossible to use silicon for storage technology. A research team from the Institute for Materials Science at Kiel University, in cooperation with the company RENA Technologies GmbH, is developing anodes made of 100% silicon, as well as a concept for their industrial production. Through targeted structuring of its surface at the micrometer level, the team can fully exploit the storage potential of silicon. This opens up a completely new approach to rechargeable batteries, as well as the energy storage of tomorrow. This week, the partners are presenting the production and potential use of silicon anodes at the Hannover Messe (23 – 27 April), at the CAU booth (Hall 2, C07).
Silicon has long been a potential candidate for the electric mobility, according to materials scientist Dr. Sandra Hansen. “Theoretically, silicon is the best material for anodes in batteries. It can store up to 10 times more energy than graphite anodes in conventional lithium-ion batteries.” Electric cars could drive further, smartphone batteries could last longer, and recharging would be significantly faster. An additional advantage of the semiconductor material is its unlimited availability—after all, sand consists largely of silicon dioxide. “Silicon is the second most abundant element on earth after oxygen, and thus an almost unlimited cost-effective resource,” said Hansen.
However, so far the lifetime of silicon anodes was far too short to really use them in chargeable and rechargeable batteries. The reason for this is the high sensitivity of the material. During charging, lithium ions move back and forth between the anode and cathode. Silicon, as the material with the highest energy density, can take up a remarkable number of lithium ions. While doing so, it expands by 400 percent and would break in the long run.
thumbnail courtesy of phys.org