Decreasing redox voltage of terephthalate-based electrode

material for Li-ion battery using substituent effect

A. E. Lakraychi,a-d F. Dolhem,b-d F. Djedaïni-Pilard,b-d A. Thiam, a,c,d C. Frayret, a,c,d M.

Becuwe*a,c,d

(a) Laboratoire de Réactivité et Chimie des Solides (LRCS), UMR CNRS 7314, Université de

Picardie Jules Verne (UPJV), Amiens, 33 rue Saint-leu, 80039 Amiens, France

(b) Laboratoire de Glycochimie, des Antimicrobiens et des Agroressources (LG2A), UMR CNRS

7378, Université de Picardie Jules Verne (UPJV), Amiens, 33 rue Saint-leu, 80039 Amiens, France

(c) Institut de Chimie de Picardie (ICP), FR 3085, 33 rue Saint-leu, 80039 Amiens, France

(d) Réseau sur le Stockage Electrochimique de l’Energie (RS2E), FR CNRS 3459, France

Synthesis details

Synthesis of the 2,5-dimethyl terephthalic acid 1:

CH3

CH3

Br

Br

CH3

CH3

CN

NC

CH3

CH3

OO

OH

OH

CuCN, NMP

200°C/6h

H2SO4/H2O

160°C/24h

LiOH.H2O

MeOH/90°C16h

40% 92% 97%

To prepare the dimethylterephthalate acid (DMT), 2.78 g (30,3 mmole) of CuCN was dissolved in 50

mL of N-methylpyrrolidone (NMP) followed by the addition of 2 g (7.56 mmole) of dibromo-p-xylene

1. The reaction mixture was kept under reflux at 200 °C for 6 hours. The mixture was precipitated in

ammonia solution 38% and was washed with an aqueous solution of Ethylene diamine tetraacetic acid

tetrasodium salt (EDTA) to obtain 1.7 g of 1,4-dicyano-2,5-dimethylbenzene 2 (40%) corresponding

1

to a brown solid. The 1,4-dicyano-2,5-dimethylbenzene 2 was hydrolyzed with H2SO4 acid in

deionized water under reflux at 160 °C for one day. The mixture was precipitated and washed several

times with water to give dimethylterephthalic acid 3 (DMT), a light brown solid.

CH3

CH3

Br

Br

CH3

CH3

CN

NC

CH3

CH3

CO2H

HO2C

Synthesis of dilithium 2,5-dimethyl-terephthalate 2:

The synthesis of dimethylterephthalate dilithium salt (Li2-DMT) was adapted from a procedure by

Ogihara et al.2. Briefly, 0.455 g (10.8 mmol, 2.1 eq) of lithium hydroxide monohydrate (LiOH.H2O)

and 1 g (5.1 mmol, 1 eq) of dimethyl terephthalic acid were ground together in a mortar and then

dissolved in 30 mL of methanol. The solution initially remained clear, with a white precipitate forming

over the course of 30 min; the obtained suspension was stirred under reflux for one night. The solid

obtained after centrifugation was washed with methanol several times and dried under vacuum at 120

°C for one day. The retrieved powder exhibits a light brown color (1 g, 98% yield).

1H liquid NMR δH (400 MHz; D2O; Me4Si) : 7.03 ( 1H, s), 2.19 ( 1H, s)

Further characterization and electrochemical tests

2

Powder X-Rays Diffraction patterns (XRPD) were acquired using a Bruker D8 diffractometer

equipped with a Cu target (Kα radiation, operating at 40kV–40mA). Patterns were collected in the 2θ

range of 10–60° with a step size of 0.03. Crystal structure resolution was not possible owing to

preferential orientation.

10 µm

Scattering angle 2θ ( � )-CoKα

Inte

nsity

(a.u

.)

Li2-DMTDMT

Figure S1: Evolution of X-rays diffraction patterns before (blue curve) and after lithiation (red curve)

C = 2.02 mg/l

0

0,1

0,2

0,3

0,4

0,5

0,6

0 0,5 1 1,5 2 2,5 3 3,5

Abso

rban

ce

Concentration (ppm)

LA107_Li2-DMT

Figure S2: Estimation of lithium stoichiometry using atomic absorption spectrometry

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% and type of Carbon

MillingTime

1st discharge capacity(x e-/mAh.g-1)

1st charge capacity(x e-/mAh.g-1)

2nd discharge capacity(x e-/mAh.g-1)

2nd charge capacity (x e-/mAh.g-1)

20th discharge capacity(x e-/mAh.g-1)/% Cth

Capacity retentionafter 20 cycles

Planetaryball mill

30% of Csp 5 h 0 Li / 0 mAh.g-1 0 Li / 0 mAh.g-1 0 Li / 0 mAh.g-1 0 Li / 0 mAh.g-1 0 mAh.g-1 -

20% of Csp +10% of SFG-44 5 h 1.6 Li / 208 mAh.g-1 0.5 Li / 65 mAh.g-1 0.5 Li / 65 mAh.g-1 0.5 Li / 65 mAh.g-1 65 mAh.g-1

31 %

10% of Csp +20% of SFG-44 5 h

1.7 Li / 221 mAh.g-1 0.8 Li / 104 mAh.g-1 0.8 Li / 104 mAh.g-1 0.8 Li / 104 mAh.g-1 104 mAh.g-1 47 %

5% of Csp +25% of SFG-44 5 h 1.7 Li / 221 mAh.g-1 0.8 Li / 104 mAh.g-1 0.8 Li / 104 mAh.g-1 0.8 Li / 104 mAh.g-1 104 mAh.g-1 47 %

Laboratoryball mill

40% of SFG-44 10min 1.7 Li / 221 mAh.g-1 0.7 Li / 91 mAh.g-1 0.7 Li / 91 mAh.g-1 0.7 Li / 91 mAh.g-1 91 mAh.g-1/35% 41 %

40% of SFG-44 30min 2.5 Li / 325 mAh.g-1 1.1 Li / 143 mAh.g-1 1.1 Li / 143 mAh.g-1 1.1 Li / 143 mAh.g-1 143 mAh.g-1/55% 44 %

40% of SFG-44 1h 2.7 Li / 351 mAh.g-1 1.1 Li / 143 mAh.g-1 1.1 Li / 143 mAh.g-1 1.1 Li / 143 mAh.g-1 143 mAh.g-1/55% 41%

30% of SFG-44 30min 2.2 Li / 286 mAh.g-1 1.1 Li / 143 mAh.g-1 1.1 Li / 143 mAh.g-1 1.1 Li / 143 mAh.g-1 143 mAh.g-1/55% 50 %

30% of SFG-44 45min 1.6 Li / 208 mAh.g-1 0.8 Li / 113 mAh.g-1 0.8 Li / 113 mAh.g-1 0.8 Li / 113 mAh.g-1 113 mAh.g-1/43% 54 %

30% of SFG-44 1h 1.8 Li / 234 mAh.g-1 0.4 Li / 52 mAh.g-1 0.4 Li / 52 mAh.g-1 0.4 Li / 52 mAh.g-1 52 mAh.g-1/20% 22 %

25% of SFG-44 1h 1.4 Li / 182 mAh.g-1 0.6 Li / 78 mAh.g-1 0.6 Li / 78 mAh.g-1 0.6 Li / 78 mAh.g-1 78 mAh.g-1/30% 43 %

20% of SFG-44 1 h 1.7 Li / 221 mAh.g-1 0.7 Li / 91 mAh.g-1 0.7 Li / 91 mAh.g-1 0.7 Li / 91 mAh.g-1 91 mAh.g-1/35% 41 %

20% of SFG-44 30 min 2.1 Li / 273 mAh.g-1 1.2 Li / 160 mAh.g-1 1.2 Li / 160 mAh.g-1 1.2 Li / 160 mAh.g-1 160 mAh.g-1/61% 58 %

20% of SFG-44 20 min 2.1 Li / 273 mAh.g-1 1.2 Li / 160 mAh.g-1 1.2 Li / 160 mAh.g-1 1.2 Li / 160 mAh.g-1 160 mAh.g-1/61% 58 %

20% of SFG-44 10 min 1.5 Li / 195 mAh.g-1 0.5 Li / 65 mAh.g-1 0.5 Li / 65 mAh.g-1 0.5 Li / 65 mAh.g-1 65 mAh.g-1/25% 33 %

Figure S3: Optimization of electrode composition and electrochemical performances

5µm

Li2-DMT + Super Pcomposite

Figure S4: Material’ and composite morphologies determined using Scanning Electron Microscopy

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18

Pote

ntia

l(V)

vs.

Li+ /L

i0

Pote

ntia

l(V)

vs.

Li+ /L

i0

Pote

ntia

l(V)

vs.

Li+ /L

i0

Pote

ntia

l(V)

vs.

Li+ /L

i0

X in Li2-DMTX in Li2-DMT

X in Li2-DMTX in Li2-DMT

1 C C/5

C/10 C/30

Figure S5: Electrochemical curve obtained for Li2-DMT composite (20% of SFG-44) at different current

rate

Figure S 6 : Electrochemical curve obtained for pure Graphite (SFG-44)

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Positive Electrode

NegativeElectrode

Voltage output

[VLi]

Capacitynegative[mAh.g-1]

Capacitypositive

[mAh.g-1]

Energynegative[Wh.Kg-1]

EnergyPositive

[Wh.Kg-1]

Energy Cell(Wh.Kg-1)

LiFePO4 Graphite 3.2 372 170 1190 540 373

LiFePO4 Li4Ti5O12 1.9 175 170 333 323 166

LiFePO4 Li2-DMT 2.8 260 170 728 476 288

LiFePO4 Li2-DMT 2.8 160* 170 448 476 230

LiFePO4 Li2-DMT 2.8 128* 170 358 476 204

* Gravimetric capacity per gram of active material* Gravimetric capacity per gram of electrode

Figure S7: Comparison of Li2-DMT with leading contender (LTO and graphite) in term of gravimetric

energy density using LiFePO4 as positive electrode material on the basis of calculation and assumption

described in the literature.3

References:

1 H. Huang, Q. He, H. Lin, F. Bai, Z. Sun and Q. Li, Polym. Adv. Technol., 2004, 15, 84–88.

2 N. Ogihara, T. Yasuda, Y. Kishida, T. Ohsuna, K. Miyamoto and N. Ohba, Angew. Chemie Int.

Ed., 2014, 53, 11467–11472.

3 Y.-C. Lu, B. M. Gallant, D. G. Kwabi, J. R. Harding, R. R. Mitchell, M. S. Whittingham and

Y. Shao-Horn, Energy Environ. Sci., 2013, 1–9.

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