In Situ and Ex Situ NMR Investigation of the Electrochemistry in Lithium Batteries
EMSL Project ID
48776
Abstract
Li-metal is an ideal anode material for rechargeable batteries. However, dendritic Li growth and limited Coulombic efficiency (CE) during repeated Li deposition/stripping processes have prevented the application of this anode in rechargeable Li metal batteries. Recently, significant progress has been made by our key collaborators at PNNL by using a highly concentrated electrolytes composed of ether solvents and LiFSI (i.e., Li[FSO2NSO2F]) salt that enables high rate cycling of a Li metal anode at high CE (up to 99.1 %) without dendrite growth. With 4 M LiFSI in 1,2-dimethoxyethane (DME) as the electrolyte, a Li|Li cell can be cycled at high rates (10 mA cm-2) for more than 6000 cycles with no increase in the cell impedance, and a Cu|Li cell can be cycled at 4 mA cm-2 for more than 1000 cycles with an average CE of 98.4%. Such excellent performance almost meets the requirements for applications in an electric car. Although these excellent high rate performances can be attributed to the apparently increased solvent coordination and increased availability of Li+ concentration in the electrolyte, the fundamental science behind this remain known. We hypothesize that (i) the dead Li-ion trapped inside the solid electrolyte interface (SEI) and the composition and the structure/morphology of the solid electrolyte interface (SEI); and (ii) the solvation structure of the Li+ in electrolyte and the relationship between the solvation structure and the SEI composition, have profound influence on the performance of the battery. Herein, we propose to use unique in situ and ex situ NMR capabilities, combined with computational modeling of NMR parameters, to carry out fundamental studies to understand the composition of SEI and the solvation structure of the Li-ion in electrolytes made of LiFSI in DME at various initial LiFSI concentrations. The results will be compared with traditional electrolytes composed of LiTFSI (i.e., Li[CF3SO2NSO2CF3]) in DME to understand why high concentration of LiFSI in DME works and why LiTFSI in DME does not work. Besides in situ NMR and computational modeling, we will also use EMSL’s advanced imaging and other spectroscopy capabilities, such as TEM, SEM, XRD and XPS to study the surface morphology and chemistry of the cycled electrodes to complement in situ NMR results. The fundamental knowledge resulted from this research will be used as a guide for our battery collaborators to design new battery electrolytes that will eventually make Li-metal battery a safe battery with high power density and high charge rate. High impact journal articles, new patents and national and international presentations will be resulted.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2015-10-01
End Date
2017-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Deng X, MY Hu, X Wei, W Wang, KT Mueller, Z Chen, and JZ Hu. 2016. "Nuclear Magnetic resonance studies of the solvation of a high-performance nonaqueous redox flow electrolyte." Journal of Power Sources 308(15 March 2016):172-179. doi:10.1016/j.jpowsour.2015.12.005
Deng X, MY Hu, X Wei, W Wang, KT Mueller, Z Chen, and JZ Hu. 2016. "Nuclear Magnetic resonance studies of the solvation of a high-performance nonaqueous redox flow electrolyte." Journal of Power Sources 308:172-179. doi:10.1016/j.jpowsour.2015.12.005
Hu J.Z., N. Rajput, C. Wan, Y. Shao, X. Deng, N.R. Jaegers, and M.Y. Hu, et al. 2018. "25Mg NMR and Computational Modeling Studies of the Solvation Structures and Molecular Dynamics in Magnesium Based Liquid Electrolytes." Nano Energy 46. PNNL-SA-130126. doi:10.1016/j.nanoen.2018.01.051
Hu J.Z., N.R. Jaegers, M.Y. Hu, and K.T. Mueller. 2018. "In Situ and Ex Situ NMR for Battery Research." Journal of Physics: Condensed Matter 30, no. 46. PNNL-SA-134425. doi:10.1088/1361-648X/aae5b8
Hu JZ, Z Zhao, MY Hu, J Feng, X Deng, X Chen, W Xu, J Liu, and J Zhang. 2016. "In situ 7Li and 133Cs Nuclear Magnetic Resonance Investigations on the Role of Cs+ Additive in Lithium-Metal Deposition Process." Journal of Power Sources 304:51-59. doi:10. 1016/j. jpowsour. 2015. 10. 067
Qian J, BD Adams, J Zheng, W Xu, WA Henderson, J Wang, ME Bowden, S Xu, JZ Hu, and J Zhang. 2016. "Anode-Free Rechargeable Lithium Metal Batteries." Advanced Functional Materials 26(39):7094-7102. doi:10.1002/adfm.201602353
Tang W, BM Goh, MY Hu, C Wan, B Tian, X Deng, C Peng, M Lin, JZ Hu, and KP Loh. 2016. "In Situ Raman and Nuclear Magnetic Resonance Study of Trapped Lithium in the Solid Electrolyte Interface of Reduced Graphene Oxide." Journal of Physical Chemistry C 120(5):2600-2608. doi:10.1021/acs.jpcc.5b12551
Wan C, MY Hu, O Borodin, J Qian, Z Qin, J Zhang, and JZ Hu. 2016. "Natural Abundance 17O, 6Li NMR and Molecular Modeling Studies of the Solvation Structures of Lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane Liquid Electrolytes." Journal of Power Sources 307:231-243. doi:10.1016/j.jpowsour.2015.12.120
Wan C, S Xu, MY Hu, R Cao, J Qian, Z Qin, J Liu, KT Mueller, J Zhang, and JZ Hu. 2017. "Multinuclear NMR Study of the Solid Electrolyte Interface Formed in Lithium Metal Batteries." ACS Applied Materials & Interfaces 9(17):14741–14748. doi:10.1021/acsami.6b15383