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High Performance Lithium Metal Negative Electrode with a Soft and Flowable Polymer Coating Guangyuan Zheng, Chao Wang, Allen Pei, Jeffrey Lopez, Feifei Shi, Zheng Chen, Austin D Sendek, HyunWook Lee, Zhenda Lu, Holger Schneider, Marina M. Safont-Sempere, Steven Chu, Zhenan Bao, and Yi Cui ACS Energy Lett., Just Accepted Manuscript • Publication Date (Web): 14 Nov 2016 Downloaded from http://pubs.acs.org on November 14, 2016
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ACS Energy Letters
High Performance Lithium Metal Negative Electrode with a Soft and Flowable Polymer Coating Guangyuan Zheng1#†, Chao Wang2#, Allen Pei1#, Jeffrey Lopez2#, Feifei Shi1, Zheng Chen2‡, Austin D. Sendek3, Hyun-Wook Lee1§, Zhenda Lu1Δ, Holger Schneider5, Marina M. Safont-Sempere5, Steven Chu4, Zhenan Bao2*, Yi Cui1,6* 1
2
Department of Materials Science and Engineering,
Department of Chemical
Engineering, 3Department of Applied Physics, and 4Department of Physics, Stanford University, California, 94305, United States. 5BASF SE, Ludwigshafen 67056, Germany. 6
Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator
Laboratory, Menlo Park, California 94025, USA Abstract The future development of low cost, high performance electric vehicles depends on the success of next-generation lithium-ion batteries with higher energy density. The lithium metal negative electrode is key to applying these new battery technologies. However, the problems of lithium dendrite growth and low coulombic efficiency have proven to be difficult challenges to overcome. Fundamentally, these two issues stem from the instability of the solid electrolyte interphase (SEI) layer, which is easily damaged by the large volumetric changes during battery cycling. In this work, we show that by applying a highly viscoelastic polymer to the lithium metal electrode, the morphology of the lithium deposition became significantly more uniform. At a high current density of 5 mA/cm2 we obtained a flat and dense lithium metal layer, and we observed stable cycling Coulombic efficiency of ~97% maintained for more than 180 cycles at a current density of 1 mA/cm2. TOC GRAPHIC
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Improved battery technology is critical for the implementation of low cost electric vehicles (EVs), which currently use batteries with a cost of around $400/kWh at the pack level.1 To lower this cost and make EVs competitive with internal combustion engine vehicles, it is necessary to develop new electrode materials with high capacity and low cost such as lithium (Li) metal and silicon negative electrodes as well as sulfur and air positive electrodes.2-7 Specifically, the Li metal negative electrode is a promising candidate for next-generation high-energy-density batteries because it has the highest theoretical specific capacity (3860 mAh/g) and the lowest potential of any negative electrode material for Li-based batteries.8 Successful application of Li metal electrodes will fundamentally enable many advanced battery technologies (Li-S and Li-Air) that can potentially offer 5-10 times higher specific energy as compared to today’s best lithium ion batteries and help reduce battery cost to meet the DOE target of
