Imidazolium ionic liquids containing LiBOB electrolyte for lithium battery

✍ Scribed by Hidesato Saruwatari; Takashi Kuboki; Takashi Kishi; Satoshi Mikoshiba; Norio Takami

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 807 KB
• Volume: 195
• Category: Article
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2009.08.081

✦ Synopsis

Bis(oxlate)borate anion (BOB -) has high reduction potential for 1-ethyl-3-methyl-imdazolium tetrafluoroborate (EMIBF 4 ) and forms solid electrolyte interface (SEI) on lithium (Li) metal surface. The addition of BOB -may make possible the use of EMIBF 4 for Li metal battery. The electrochemical properties of ionic liquids containing EMIBF 4 were analyzed. We investigated the stability of LiBOB/EMIBF 4 and LiBF 4 /EMIBF 4 electrolyte for Li metal and the performance of Li/MnO 2 batteries with the electrolytes by 1 H NMR, ac impedance spectra and the electrochemical method. From the 1 H NMR spectra, LiBOB/EMIBF 4 was stable for Li metal and LiBF 4 /EMIBF 4 was reduced on the surface of Li metal. The discharge capacity of MnO 2 cathode with LiBOB/EMIBF 4 was 235 mAh g -1 . Li metal plating and stripping and Li-Al alloying reaction were reversible in LiBOB/EMIBF 4 . Charge-discharge reaction of Li-Al alloy in LiBOB/EMIBF 4 had a high coulomb efficiency. The coulomb efficiency at 1st cycle was 86% and the efficiency at 5th cycle was up to 94%.