Electrochemical Behaviors of LMn_(1-x)Fe_xPT_4/C Cathode Materials in an Aqueous Electrolyte with/without Dissolved Oxygen

摘要

Olivine LiMn_(1-x)Fe_xPO_4 (x = 0.5, 0.4, 0.3, 0.2) coated with carbon are prepared as the cathode materials for the aqueous rechargeable lithium-ion batteries (ARLBs). Li~+ insertion-extraction behaviors of the as-prepared materials in LiNO_3 aqueous electrolyte with/without dissolved oxygen are studied by cyclic voltammograms (CVs) and electrochemical impedance spectra (EIS). The Li~+ diffusion coefficient of LiMn_(1-x)Fe_xPO_4 in LiNO_3 aqueous electrolyte is first reported. The results indicate that eliminating the dissolved oxygen in the aqueous electrolyte could decrease the charge transfer-resistance and increase the Li~+ diffusion coefficient of (LiMn_(1-x)Fe_xPO_4/C)//LiV_3O_8 ARLBs, which also improves the electrochemical properties of the ARLBs. The initial discharge specific capacity of LiMn_(0.6)Fe_(0.4)PO_4/C is 112 mA h g~(-1) at 0.1 C-rate, which provides a new candidate cathode material for ARLBs.