Suppression of Self-Discharge by a LiPF₆/Methyl Difluoroacetate Electrolyte in Li/CuCl₂Batteries

Abstract

Methyl difluoroacetate (MFA) was used as an electrolyte solvent in Li/CuCl2 batteries, and the LiPF6/MFA electrolyte was effective for the suppression of the self-discharge of Li/CuCl2 batteries. The dependence of self-discharge behavior on LiPF6 concentration (1.0, 1.4, 1.8, 2.2, and 2.7 mol dm−3) in MFA-based electrolytes was investigated. The lowest self-discharge was observed for a 2.2 mol dm−3 LiPF6/MFA electrolyte under the described conditions, and an initial discharge capacity of 395 mAh g−1 was maintained after 678 h (4 weeks) of rest. The cycling performance of the LiPF6/MFA electrolytes was evaluated, and the discharge capacity for the 2.2 mol dm−3 LiPF6/MFA electrolyte was found to be maintained at 183 mAh g−1 (10th cycle). Therefore, 2.2 mol dm−3 LiPF6/MFA electrolyte is confirmed to be effective for the suppression of the self-discharge of Li/CuCl2 batteries.

Charge-Discharge Characteristics of Li/CuCl_2 Batteries with LiPF_6/Methyl Difluoroacetate Electrolyte

“…MFA (Tokyo Chemical Industry Co. Ltd.) was used as the electrolyte solvent, and its water content was ≤ 50 ppm and the purity was > 99%. The salt LiPF 6 was dissolved in MFA at 2.2 mol L -1 , a concentration found to produce the lowest self-discharge in our previous study 13) .…”

“…Discs 5 mm in diameter were punched out of the composite sheets, and then pressed onto a Pt mesh (Sanwakinzoku Co., 100 mesh) at 10 MPa pressure to prepare the Cu/LiCl electrodes. The CuCl2/C electrodes were prepared as described in a previous paper 13) . The carbon material used was acetylene black (AB, DENKA BLACK).…”

“…Our previous study reported the cycling performance of the Li/CuCl 2 batteries with 2.2 mol L -1 LiPF 6 /MFA. The charge-discharge conditions were: charged upper limit voltage: 3.6 V, discharged lower limit voltage: 2.5 V, and discharge and charge currents: 0.01 C 13) . In the first discharge process, the first clear plateau at 3.4 V was attributed to the Cu reduction reaction [2], and the second clear plateau at 2.7 V to the Cu reduction reaction [3].…”

“…Based on previous characterization of the CuCl 2 /C electrode with LiPF 6 /MFA 13) , in this work we first evaluate the effect of raising the charged upper limit voltage from 3.6 to 4.0 V. Then the Cu/LiCl electrode was investigated as a re-conversion reaction cathode with LiPF 6 /MFA in LIBs. The mechanisms of the re-conversion reaction, and the fundamental characteristics of the charge and discharge processes were examined.…”

High Performance Na–CuCl2 Rechargeable Battery toward Room Temperature ZEBRA‐Type Battery

“…Metal halide materials (MX n ; M: Fe, Cu, Ni, etc. and X: F, Cl, and Br) deserve to be regarded as alternative high‐capacity electrode materials to replace conventional intercalation‐based metal oxide materials for Na rechargeable batteries owing to their high theoretical capacity combined and low cost . Among them, NiCl 2 is now being used as a cathode material for ZEBRA (Zero Emission Battery Research Activities) battery, which is one of the most promising sodium rechargeable battery systems for large‐scale power storage for renewable energies.…”