Supplemental Information

Li2O2 as a Cathode Additive for the Initial Anode

Irreversibility Compensation in Lithium-Ion Batteries

Yitian Bie, Jun Yang, Jiulin Wang, Jingjing Zhou,Yanna Nuli

School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai,

200240, China

Corresponding author: J. Yang, yangj723@sjtu.edu.cn

Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 2017

Experimental Details

Electrodes preparation: For the preparation of NCM electrode, NCM (Minnesota Mining and

Manufacturing), SP (Timical) and PVDF (Shanghai Xiaoyuan Technology) were mixed by an

82:10:8 weight ratio in NMP. After stirring for 5 h, the slurry was coated on an Al foil current

collector and then dried at 80 °C in vacuum for 6 h. The foil was cut to Φ12 mm sheets to assemble

cells.

NCM was ball-milled for 6 h to obtain fine NCM-6h. Li2O2 was purchased from Alfa Aesar. For

the preparation of Li2O2, Li2O2/NCM-6h and NCM/NCM-6h/Li2O2 electrodes, 0.46g electrode

materials (Li2O2, Li2O2+NCM-6h or Li2O2+NCM+ NCM-6h) and SP were blended in NMP. After

the slurries were stirred for 4 h in Ar atmosphere, 0.4 g PVDF solutions (PVDF in NMP, 10%) were

added. After stirring for another half hour, the slurries were coated on Al foils in air and then dried

at 80 °C in vacuum for 6 h. The materials ratio except PVDF for Li2O2 and Li2O2/NCM-6h

electrodes are 5 Li2O2: 2 SP and 5 Li2O2: 2 SP: 1 NCM-6h in weight. Li2O2 and SP were ball-milled

for half an hour in advance. In NCM/NCM-6h/Li2O2 electrodes, Li2O2 was also ball-milled with

part of SP in ratio of 5:2 in advance and the materials ratio in the electrodes is 76 NCM: 1 NCM-

6h: 5Li2O2: 10 SP: 8 PVDF or 79 NCM: 1 NCM-6h: 2 Li2O2:10 SP: 8 PVDF. The slurries preparing

routs are the same as above. The active materials loadings of the cathodes are 3.8~4.0 mg cm-2.

Graphite (Timical), SP and PVDF were blended in a ratio of 92:3:5 in NMP to prepare graphite

anodes. The rest routes are the same as NCM electrode. For graphite/Si and SiO anodes, the

materials ratios are 65 graphite: 15 Si: 5 SP: 15 PAA and 60 SiO: 20 SP: 20 PAA, respectively. All

materials were blended in water. The rest routes are the same as NCM electrode. Si nanoparticles

from Alfa Aesar and SiO from Shanghai Shanshan Technology were used. The capacity ratio of the

negative electrode to the positive electrode (N/P ratio) used for the full cells was 1.04.

Cells assembling and electrochemical tests: The electrochemical performances of the as-prepared

electrodes were tested via CR2016 coin cells with ENTEK ET20-26 as separator. The cells were

assembled in an argon-filled glove box (MB-10 compact, MBraun) using 1M LiPF6/EC+DMC (1:1

by volume, ethylene carbonate (EC), dimethyl carbonate (DMC)) as electrolyte. The cycling

performances were evaluated by a LAND battery test system (Wuhan Kingnuo Electronics Co.,

Ltd., China) at 25 °C. The specific capacity was calculated on the basis of NCM and NCM-6h. CV

test was carried out between 2.8-4.6 V Li/Li+ with a scanning rate of 0.1 mV s-1 on a CHI760E

electrochemical workstation (Chenhua, Shanghai, China).

Morphology and structure characterization: The morphologies and microstructures of the materials

were observed by a FEI Nova SEM 230 ultra-high resolution FESEM.

Fig. S1 XRD patterns of Li2O2 and Li2O2/NCM electrode before and after charging.

Fig. S2 The initial charge/discharge curves for NCM, NCM/Li2O2 and NCM/NCM-6h/Li2O2 electrodes.

Fig. S3 The initial charge/discharge curves of full cells with NCM and NCM/NCM-6h/2%Li2O2 cathodes with a cut-off of 2.0-4.4 V. The anodes are graphite.

Fig. S4 The charge/discharge curves of full cells with NCM and NCM/NCM-6h/2%Li2O2 cathodes. The anodes are graphite/Si (a) and SiO (b).

Fig. S5 The initial charge/discharge curves of graphite (a), graphite/Si (b) and SiO (c) anodes.

Table S1. The initial charge/discharge properties of coin half-cells with NCM and NCM/NCM-6h/Li2O2 electrodes between 2.8 and 4.6 V versus Li+/Li at a current

density of 0.1C.wt. % Li2O2 in the electrode

Charge capacity [mA h g-1]

Discharge capacity [mA h g-1]

Coulombic efficiency [%]

Capacity of Li2O2 [mA h g-1]

0 227.9 193.0 84.7 -

2 255.9 191.2 74.7 1098.8

5 299.6 186.8 62.3 1095.8

Table S2. The Coulombic efficiencies of anodes in half cells and initial reversible cathode capacities in full cells.

Cathode Anode Anode initial efficiency in half cell (0.01-1.2V vs. Li/Li+)[%]

Initial reversible cathode capacity in full cell (1.8-4.6V) [mA h g-1]

NCM Graphite 91.9 192.0

NCM/NCM-6h/2% Li2O2 Graphite 91.9 207.1

NCM Graphite/Si 83.5 174.7

NCM/NCM-6h/2% Li2O2 Graphite/Si 83.5 187.5

NCM SiO 70.1 143.7

NCM/NCM-6h/2% Li2O2 SiO 70.1 172.9

Table S3. Comparison of different cathode additives for Li compensation.Cathode additives

Remnants Additional charge capacity [mA h g-

1]

Additional charge capacity per remnant [mA h g-1]

Special conditions Ref.

Co/Li2O Co3O4, unreacted additives

619 737 7

Co/LiF CoF3, unreacted additives

516 595 8

Co/Li2S CoS2, unreacted additives

711 871 9

Li3N unreacted additives

1584~1946 5280~11676 Using PTFE as binder, electrode preparing in Ar atmosphere

10

Li2O unreacted additives

433~1083 570~2707 Using specific electrolytes and anodes, high charge voltage (4.7 V)

11

Li5FeO4 LiFeO2 700 1147 Electrode preparing in Ar atmosphere

12

Li5ReO6 ReO3.5 410 531 13Li2O2 5% impurity in

commercially available Li2O2

1095 17520 Using 1% ball-milled NCM as catalyst with poor cycle performance

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