TECHNOLOGY AREA(S): Materials
OBJECTIVE: Develop and characterize flexible microporous electrodes for lithium metal secondary batteries.
DESCRIPTION: The DoD has need for inherently safe energy storage devices with improved high power, high energy density, and low temperature performance to reduce dismounted soldier burden. Lithium metal batteries offer an opportunity to increase energy density because lithium has the highest theoretical capacity (3,860 mAh/g) and lowest electrochemical potential (3.04 V). However, the use of lithium metal has posed challenges such as limited cycle life and the propensity to form lithium metal dendrites which can reduce capacity and lead to short circuits. In addition, the presence of lithium metal, with its high reactivity, poses a concern if the battery is compromised and the lithium is exposed to the atmosphere. Flexible microporous electrodes have been predicted to reduce dendrite growth due to confinement of lithium in individual pores while simultaneously increasing charge/discharge rates due to the high surface area. Advantages derived from the use of microporous electrodes include: high energy density, fast charge and discharge rates, and long cycle life. In addition, depending upon the selection of microporous support material the batteries could also be flexible and containment of lithium in individual micropores could increase safety. This effort will develop and characterize flexible microporous electrodes to enable conformal, safe, lithium metal batteries.
PHASE I: Demonstrate and optimize flexible microporous electrodes with lithium metal electrodes. Determine structure property relationships between pore size and distribution and their impacts on electrochemical performance including formation of dendrites and half cell cycle life. Evaluate electrolyte formulations to ensure support material compatibility. Prepare laboratory half cells, perform high power and specific energy testing, and identify degradation processes. Demonstrate results that indicate that a specific energy >350 Wh/kg and improved life cycle performance of >150 cycles with 80% capacity retention are possible using flexible microporous electrodes.
PHASE II: Extend microporous electrode technology to cathode and evaluate a at least 3 cathode materials. Evaluate cathode half cells to optimize electrochemical properties. Determine structure property relationships between pore size and distribution and their impacts on electrochemical performance. Continue optimization of lithium metal anodes. Prepare complete batteries (over 1000mAh), perform high power and specific energy testing, and identify degradation processes. Demonstrate results with a specific energy >400 Wh/kg and improved life cycle performance of >300 cycles with >90% capacity retention.
PHASE III: Development of devices for both civilian and DoD use. There are many electronic devices used in the military and civilian communities that would benefit from increased energy storage. Portable electronics, hybrid vehicles, etc. performance will be improved if safe lithium metal secondary batteries with high cycle are developed.
1: Jianming Zheng, Mark H. Engelhard, Donghai Mei, Shuhong Jiao, Bryant J. Polzin, Ji-Guang Zhang, Wu Xu. Electrolyte additive enabled fast charging and stable cycling lithium metal batteries. Nature Energy, 2017
2: 2 (3): 17012 DOI: 10.1038/nenergy.20112
3: Nobuhiro Ogihara, Yuichi Itou, Tsuyoshi Sasaki, and Yoji Takeuchi. Impedance Spectroscopy Characterization of Porous Electrodes under Different Electrode Thickness Using a Symmetric Cell for High-Performance Lithium-Ion Batteries. J. Phys. Chem. C 2015, 119, 4612-4619: DOI: 10.1021/jp512564f
4: Jelle Smekens, Rahul Gopalakrishnan, Nils Van den Steen, Noshin Omar, Omar Hegazy, Annick Hubin and Joeri Van Mierlo. Influence of Electrode Density on the Performance of Li-Ion Batteries: Experimental and Simulation Results, Energies 2016, 9, 104
6: Nobuhiro Ogihara, Yuichi Itou, Tsuyoshi Sasaki, and Yoji Takeuchi. Impedance Spectroscopy Characterization of Porous Electrodes under Different Electrode Thickness Using a Symmetric Cell for High-Performance Lithium-Ion Batteries. J. Phys. Chem. C 2015, 119, 4612-461 DOI: 10.1021/jp512564f
KEYWORDS: Lithium Metal Battery, Porous Electrodes, Secondary Battery