Increasing Li-S Battery Cycle Life, and Improving Safety, through Application of a Variety of Coating Techniques

摘要

Lithium-sulfur batteries offer the highest theoretical specific energy of any electrochemical couple involving only solid elements, more than four times that of the highest energy lithium-ion chemistries in use today. To date, commercialization has been slow due to cycle-life limitations. The major cycle life failure mechanisms are traceable to solvent reactions with the metallic lithium anode, while safety is dominated by anode reactions with sulfur. However, specific and volumetric energy are controlled by cathode structure and solvent uptake. The fundamental aspects of lithium-sulfur chemistry are reviewed here, primary lithium-sulfur failure mechanisms are discussed and various approaches to increase cycle life, increase specific and volumetric energies and improve safety are presented. These approaches include: doped, vacuum deposited lithium, utilizing a sputtered current collector; a combination of vacuum deposited lithium ion conducting ceramic/polymer multi-layer coatings; an atmospherically coated polymeric separator layer; atmospherically coated cathodes with engineered porosity; and uniaxial pressure applied to the packaged cell. Limited performance data is presented.