Dual-graphite cells based on the reversible intercalation of bis(trifluoromethanesulfonyl)imide anions from an ionic liquid electrolyte

作者：Rothermel, Sergej^*; Meister, Paul; Schmuelling, Guido; Fromm, Olga; Meyer, Hinrich-W.; Nowak, Sascha; Winter, Martin; Placke, Tobias

来源：Energy & Environmental Science, 2014, 7(10): 3412-3423.

DOI：10.1039/c4ee01873g

• LITHIUM SALT ELECTROLYTES
• ELECTROCHEMICAL INTERCALATION
• ETHYLENE SULFITE
• IMIDE ANIONS
• PERFORMANCE
• INSERTION
• EFFICIENCY
• ADDITIVES
• BATTERIES
• CAPACITY

Recently, dual-ion cells based on the anion intercalation into a graphite positive electrode have been proposed as electrochemical energy storage devices. For this technology, in particular electrolytes which display a high stability vs. oxidation are required due to the very high operation potentials of the cathode, which may exceed 5 V vs. Li/Li+. In this work, we present highly promising results for the use of graphite as both the anode and cathode material in a so-called "dual-graphite" or "dual-carbon" cell. A major goal for this system is to find suitable electrolyte mixtures which exhibit not only a high oxidative stability at the cathode but also form a stable solid electrolyte interphase (SEI) at the graphite anode. As an electrolyte system, the ionic liquid-based electrolyte mixture Pyr(14)TFSI-LiTFSI is used in combination with the SEI-forming additive ethylene sulfite (ES) which allows stable and highly reversible Li+ ion and TFSI- anion intercalation/de-intercalation into/from the graphite anode and cathode, respectively. By addition of ES, also the discharge capacity for the anion intercalation can be remarkably increased from 50 mA h g(-1) to 97 mA h g(-1). X-ray diffraction studies of the anion intercalation into graphite are conducted in order to understand the influence of the electrolyte additive on the graphite structure and on the cell performance.

• 出版日期2014-10