J. Electrochem. Sci. Technol., 2022, 13(1), 78-89

A LiPF6-LiFSI Blended-Salt Electrolyte System for Improved

Electrochemical Performance of Anode-Free Batteries

Haeyoung Choi1,2†*, YeoJi Bae1,3,†, Sang-Min Lee1, Yoon-Cheol Ha1, Heon-Cheol Shin3,*, Byung Gon Kim1,*1Next Generation Battery Research Center, Korea Electrotechnology Research Institute, 12, Jeongiui-gil, Seongsan-gu,

Changwon-si, Gyeongsangnam-do 51543, Republic of Korea2School of Chemical and Biological Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Repub-

lic of Korea3School of Materials Science and Engineering, Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu,

Busan, 46241, Republic of Korea

Fig. S1. Electrochemical performance of the LFP/Cu cells using LiFSI electrolytes on the variation of salt concentration

from 1 to 4 M in the voltage range of 2.8 – 4.2 V vs. Li/Li+. (a) Cycling performance and (b) its corresponding

couloumbic efficiency. DOL/DME(1/1, v/v) + 2wt% LiNO3 was used as a solvent.

Fig. S2. Digital photographs and SEM images of the plated Li morphologies on the Cu foils after the first Li plating in the

x M LiPF6 in EC:EMC:DEC (3/5/2, v/v) + 5wt%FEC + 2wt%VC (x = 1, 2, 3, and 4) electrolytes.

Supporting Information

†These authors contributed equally to this work.

*E-mail address: ssunzero@keri.re.kr (H. Choi), hcshin@pusan.ac.kr (H.-C. Shin), byunggonkim@keri.re.kr (B. G. Kim)

DOI: https://doi.org/10.33961/jecst.2021.00535

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) whichpermits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Haeyoung Choi et al. / J. Electrochem. Sci. Technol., 2022, 13(1), 78-89

Fig. S3. Digital photographs and SEM images of the plated Li morphologies on the Cu foils after the first Li plating in the

(a) 0.5M LiPF6 + 0.5M LiFSI, (b) 1M LiPF6 + 1M LiFSI, (c) 1.5M LiPF6 + 1.5M LiFSI, (d) 2M LiPF6 + 2M LiFSI, (e)

3.8M LiPF6 + 0.2M LiFSI, (f) 0.2M LiPF6 + 3.8M LiFSI, and (g) 0.2M LiPF6 + 3.8M LiFSI TEP + 0.2wt% LiNO3

electrolytes.

Fig. S4. Digital photographs and SEM images of the plated Li morphologies on the Cu foils after the 50th Li plating in the

(a) 0.5M LiPF6 + 0.5M LiFSI, (b) 1M LiPF6 + 1M LiFSI, (c) 1.5M LiPF6 + 1.5M LiFSI, (d) 2M LiPF6 + 2M LiFSI, (e)

3.8M LiPF6 + 0.2M LiFSI, (f) 0.2M LiPF6 + 3.8M LiFSI, (g) 0.2M LiPF6 + 3.8M LiFSI TEP + 0.2wt% LiNO3 electrolytes.

Haeyoung Choi et al. / J. Electrochem. Sci. Technol., 2022, 13(1), 78-89

Table S1. Ionic conductivities at the various salt and solvent combinations.

Ionic conductivity (mS/cm)

Salts/Solvents DOL/DME(1/1)DOL/DME(1/1)

+LiNO3

EC/DEC/EMC

(3/5/2)

EC/DEC/EMC(3/5/2)

+5wt%FEC+2wt%VC

LiFSI 11.90 10.81 14.56

1M /11.5

2M /9.26

3M /7.54

4M /5.82

LiPF6 1.55 11.56 12.62

1M /8.92

2M /6.97

3M /4.87

4M /2.11

LiFSI:LiPF6 (1:1) - - -

1M /11.02

2M / 8.01

3M / 5.73

4M / 2.98

xLiFSI:yLiPF6

(X:Y, X+Y=4M)- - -

0.2:3.8/2.35

3.8:0.2/4.54