Details

Autor(en) / Beteiligte

• Wang, Zhigang
• Zhuang, Shuxin
• Lu, Mi
• Gong, Zhengliang

Titel

Exploring 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether as a high voltage electrolyte solvent for 5-V Li2CoPO4F cathode

Ist Teil von

• Journal of solid state electrochemistry, 2021-04, Vol.25 (4), p.1353-1360

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 1,1,2,2-Tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (F-EPE) is investigated as a cosolvent for high voltage electrolytes of Li 2 CoPO 4 F. Compared with conventional carbonate-based electrolyte (1-M LiPF 6 ethylene carbonate [EC]/dimethyl carbonate [DMC] [1:1, wt:wt]), 1 M LiPF 6 F-EPE/DMC (1:2, wt:wt) exhibits significantly improved antioxidant ability in high voltage, thus greatly enhances the electrochemical performance of 5.0-V Li 2 CoPO 4 F/Li cells. Linear sweep voltammetry (LSV) and charging/discharging tests demonstrate that the F-EPE/DMC electrolyte possesses both a high oxidation voltage up to 6.2 V vs. Li + /Li on Pt electrode and superior oxidation stability on Li 2 CoPO 4 F cathode. Benefiting from its high antioxidant ability, the capacity retention of Li 2 CoPO 4 F cathode increases from 15% in EC/DMC electrolyte to 51% in F-EPE/DMC electrolyte after 100 cycles at 1 C between 3.0 and 5.4 V. Moreover, differential capacity (d Q /d V ) analysis, electrochemical impedance spectroscopy, ex situ X-ray diffraction, and X-ray photoelectron spectroscopy are used to analyze the effects of F-EPE/DMC electrolyte on the improved electrochemical performance. It is illustrated that the high stability of F-EPE/DMC electrolyte effectively inhibits the oxidative decomposition of the electrolyte on Li 2 CoPO 4 F electrode above 5.0 V and suppresses the damage to the surface of Li 2 CoPO 4 F, thus alleviate the increase in electrode polarization and cell impedance.