Time：Sep. 6th, 2016, 10:00
Location： Conference Hall of Basic Energy Building
Dr. Ji-Guang Zhang
Energy & Environment Directorate, Pacific Northwest National Laboratory
Abstract：
Rechargeable metal batteries, such as Li metal batteries are considered the “holy grail” of energy storage systems. However, dendritic metal growth and limited Coulombic efficiency (CE) during metal deposition/stripping have prevented their practical applications in rechargeable batteries. In this presentation, I will first give an overview on the recent development in this field, then discuss our recent works in this field. During the last a few years, we have developed several approaches to suppress metal dendrite growth and enhance the Coulombic efficiency (CE) of metal deposition/stripping processes. Several electrolyte additives, including CsPF6, RbPF6, and trace-amount of H2O (25-50 ppm) have been found to be effective for achieving dendrite-free Li metal deposition in LiPF6-based electrolytes. Furthermore, we have developed a highly concentrated electrolytes composed of the lithium bis(fluorosulfonyl)imide (LiFSI) salt and 1,2-dimethoxyethane (DME) solvent which enables high rate cycling of Li metal anode at high CE (up to 99.1 %) without dendrite growth. It is demonstrated that a Li|Li cell can be cycled at high rates (10 mA cm-2) for more than 6,000 cycles with no increase in the cell impedance and no dendritic Li growth. A Li|Cu cell can be cycled at 4 mA cm-2 for more than 1,000 cycles with an average CE of 98.4%. By optimizing the electrolyte compositions and various operating parameters, we have demonstrated Anode-free rechargeable lithium (Li) batteries based on a Cu||LiFePO4 cell structure with an extremely high CE (> 99.8%). Further development of this technology will accelerate the commercialization of next generation of Li metal batteries.
Introduction：
Dr. Zhang is a Laboratory Fellow in the Energy Processes & Materials Division at Pacific Northwest National Laboratory (PNNL). He is the PI on PNNL's efforts on Energy Storage for Transportation supported by the DOE/EERE/OVT office and PNNL's Transformation Materials Science Initiative.
Research Interests
1) Energy storage materials and devices: lithium batteries, lithium ion batteries and Li-S batteries;
2) Energy saving materials and devices: electrochromics materials and devices, thermochromic materials and devices;
3) Solid state electrolyte and solid state batteries: thin film batteries and solid state Li-S batteries.
Education
Ph.D., in Experimental Condensed Matter Physics, University of Kentucky, 1990.
M.S., in Theoretical Physics, Dalian University of Technology, Dalian, China, 1984.
B.S., in Applied Physics, Dalian University of Technology, Dalian, China, 1982.
Contacts：Group DNL0306 Guo-Xu Wang（9811）