High Coulombic efficiency aluminum-ion battery using an AlCl ₃ -urea ionic liquid analog electrolyte

Journal Article · Tue Jan 17 00:00:00 EST 2017 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.1619795114· OSTI ID:1339583

Angell, Michael ^[1]; Pan, Chun-Jern ^[2]; Rong, Youmin ^[1]; Yuan, Chunze ^[1]; Lin, Meng-Chang ^[3]; Hwang, Bing-Joe ^[4]; Dai, Hongjie ^[1]

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1. Department of Chemistry, Stanford University, Stanford, CA 94305,
2. Department of Chemistry, Stanford University, Stanford, CA 94305,, Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan,
3. College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao 266590, People's Republic of China,
4. Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan,, National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan

In recent years, impressive advances in harvesting renewable energy have led to a pressing demand for the complimentary energy storage technology. In this paper, a high Coulombic efficiency (~99.7%) Al battery is developed using earth-abundant aluminum as the anode, graphite as the cathode, and a cheap ionic liquid analog electrolyte made from a mixture of AlCl₃ and urea in a 1.3:1 molar ratio. The battery displays discharge voltage plateaus around 1.9 and 1.5 V (average discharge = 1.73 V) and yielded a specific cathode capacity of ~73 mAh g^-1 at a current density of 100 mA g^-1 (~1.4 C). High Coulombic efficiency over a range of charge–discharge rates and stability over ~150–200 cycles was easily demonstrated. In situ Raman spectroscopy clearly showed chloroaluminate anion intercalation/deintercalation of graphite (positive electrode) during charge–discharge and suggested the formation of a stage 2 graphite intercalation compound when fully charged. Raman spectroscopy and NMR suggested the existence of AlCl₄^-, Al₂Cl₇^- anions and [AlCl₂·(urea)_n]⁺ cations in the AlCl₃/urea electrolyte when an excess of AlCl₃ was present. Aluminum deposition therefore proceeded through two pathways, one involving Al₂Cl₇^- anions and the other involving [AlCl₂·(urea)_n]⁺ cations. Finally, this battery is a promising prospect for a future high-performance, low-cost energy storage device.

• Research Organization: Stanford Univ., CA (United States); National Taiwan Univ. of Science and Technology, Taipei (Taiwan); Shandong Univ. of Science and Technology, Qingdao (China)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); Ministry of Education of Taiwan; Taishan Scholar Project for Young Scholars of Shandong Province of China
• Grant/Contract Number: SC0016165; NTUST 104DI005
• OSTI ID: 1339583
• Alternate ID(s): OSTI ID: 1465681
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 114 Journal Issue: 5; ISSN 0027-8424
• Publisher: Proceedings of the National Academy of Sciences
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
aluminum-ion battery
urea electrolyte
ionicity
ionic liquid
energy storage