New Nanostructured Li2S/Silicon Rechargeable Battery with High Specific Energy

Abstract

Rechargeable lithium ion batteries are important energy storage devices; however, the specific energy of existing lithium ion batteries is still insufficient for many applications due to the limited specific charge capacity of the electrode materials. The recent development of sulfur/mesoporous carbon nanocomposite cathodes represents a particularly exciting advance, but in full battery cells, sulfur-based cathodes have to be paired with metallic lithium anodes as the lithium source, which can result in serious safety issues. Here we report a novel lithium metal-free battery consisting of a Li₂S/mesoporous carbon composite cathode and a silicon nanowire anode. This new battery yields a theoretical specific energy of 1550 Wh kg⁻¹, which is four times that of the theoretical specific energy of existing lithium-ion batteries based on LiCoO₂ cathodes and graphite anodes (∼410 Wh kg⁻¹). The nanostructured design of both electrodes assists in overcoming the issues associated with using sulfur compounds and silicon in lithium-ion batteries, including poor electrical conductivity, significant structural changes, and volume expansion. We have experimentally realized an initial discharge specific energy of 630 Wh kg⁻¹ based on the mass of the active electrode materials.