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

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 AlCl 3 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 AlCl 4 -, Al 2Cl 7 - anions and [AlCl 2·(urea) n] + cations in the AlCl 3/urea electrolyte when an excess of AlCl 3 was present. Aluminum deposition therefore proceeded through two pathways, one involving Al 2Cl 7 - anions and the othermore » involving [AlCl 2·(urea) n] + cations. Finally, this battery is a promising prospect for a future high-performance, low-cost energy storage device.« less
 [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [4] ;  [1]
  1. Stanford Univ., CA (United States). Dept. of Chemistry
  2. Stanford Univ., CA (United States). Dept. of Chemistry; National Taiwan Univ. of Science and Technology, Taipei (Taiwan). Dept. of Chemical Engineering
  3. Shandong Univ. of Science and Technology, Qingdao (China). College of Electrical Engineering and Automation
  4. National Taiwan Univ. of Science and Technology, Taipei (Taiwan). Dept. of Chemical Engineering; National Synchrotron Radiation Research Center, Hsinchu (Taiwan)
Publication Date:
Grant/Contract Number:
SC0016165; NTUST 104DI005
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 114; Journal Issue: 5; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Stanford Univ., CA (United States); National Taiwan Univ. of Science and Technology, Taipei (Taiwan); Shandong Univ. of Science and Technology, Qingdao (China)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Ministry of Education of Taiwan; Taishan Scholar Project for Young Scholars of Shandong Province of China
Country of Publication:
United States
25 ENERGY STORAGE; aluminum-ion battery; urea electrolyte; ionicity; ionic liquid; energy storage
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1465681