SusChEM: Ultra-High Li+ Ion Conductivity Chemically Stable Mechanically Strong Mixed Oxy-Sulfide Solid Electrolytes

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Principal Investigator: Steve W. MartinNumber: 1438223Lithium batteries used in electric and hybrid vehicles suffer from many problems. Current designs can hold 10% of their theoretical amount of energy content, contain highly flammable organic liquids, are relatively costly, and do not last as long as a typical automobile. New materials are needed to address these problems. In particular, advanced ceramic materials have the potential to solve these problems by enabling the manufacture of high capacity, safe, low-cost, and long-lasting solid state lithium batteries. Towards this end, this research will incorporate both oxygen and sulfur into the ceramic material used in these batteries to make new oxygen-sulfide ceramic materials with desirable properties. The overall goal of this project is to develop and study this new class of mixed oxy-sulfide ceramic materials for lithium batteries. Oxide materials are safe and have good mechanical strength, whereas sulfide materials allow for the fast lithium ion transfer needed for rapid electricity discharge and re-charging. The project is also designed to promote student learning and professional development in the context of this research through mentoring and leadership activities. To broaden participation, existing successful programs at Iowa State University will be used to collaborate with minority-focused institutions and minority programs to provide research experiences for students from underrepresented groups in science and engineering. The project will also collaborate with federal government laboratories and automotive companies engaged in automotive battery research.Technical DescriptionThe overall goal of this project is to develop and study a new class of mixed oxy-sulfide ceramics for use in solid-state lithium batteries in scalable electrochemical energy storage systems. All-oxide solid electrolytes possess excellent chemical durability and good mechanical strength, but have to be processed at very high temperatures, and possess lithium ion conductivities that are too low for automotive applications. All-sulfide solid electrolytes possess extremely high lithium ion conductivities, can be easily processed at room temperature, but are very reactive with both air and moisture. This project will investigate the potential of mixed oxy-sulfide solid electrolytes to provide desirable characteristics associated with both oxide and sulfide ceramic materials. Preliminary work on all-sulfide solid electrolytes has demonstrated that the addition of molecular oxygen to the electrolyte decreased the volumetric strain energy for lithium ion conduction by replacing bridging sulfurs. This project will study this new mixed oxy-sulfide mixed network for the potential to simultaneously reduce both the strain and coulomb components of the conductivity activation energy. The new solid-state chemistries are expected to lead to high conductivity, high chemical durability, and mechanically strong mixed oxy-sulfide based solid electrolytes. The project is also designed to promote student learning and professional development in the context of this research through mentoring and leadership activities. To broaden participation, existing successful programs at Iowa State University will be used to collaborate with minority-focused institutions and minority programs to provide research experiences for students from underrepresented groups in science and engineering. The project will also collaborate with federal government laboratories and automotive companies engaged in automotive battery research.