Materials selection for asymmetric/hybrid supercapacitorscii-resource.com/.../Wohlfahrt-Mehrens_Margret.pdf · M. Wohlfahrt-Mehrens . Materials selection for asymmetric/hybrid supercapacitors

Zentrum für Sonnenenergie- und Wasserstoff-Forschung (ZSW) Baden-Württemberg

AABC 2017, 30 January -2 February 2017 Mainz, Germany

S. Dsoke, M. Secchiaroli, E. Gucciardi, H. Y. Tran, B. Fuchs, S. Calcaterra,

M. Wohlfahrt-Mehrens

Materials selection for asymmetric/hybrid supercapacitors

Modulation of energy and power Asymmetric or (hybrid) supercapacitors

Ion adsorptionLi insertion

--

-

-

--

- -

Li+

metal oxidecarbon

+-

--

-

-

--

- -

--

-

-

--

- -

Li+Li+

metal oxidecarbon

+-

Li insertionmaterial

Ion adsorptionLi insertion

--

-

-

--

- -

Li+

metal oxidecarbon

+-

--

-

-

--

- -

--

-

-

--

- -

Li+Li+

metal oxidecarbon

+-


--

-

-

--

- -

Li+

metal oxidecarbon

+-

--

-

-

--

- -

--

-

-

--

- -

Li+Li+

metal oxidecarbon

+-


Hybridization at cell level Hybridization at electrode level

- 1 -

Behavior of carbonaceous materials in battery-like electrolytes

Cell Balancing (mass ratio, thicknesses, cell

voltage)

Electrode formulation with environmental friendly and cheaper

binders as an alternative to PVDF

Electrode processing optimization (composition, thickness, compaction,

adhesion)

current collector

Activated Carbon Electrode

LTOElectrode

Separatorcurrent collector

20 µm 245 µm

20 µm 85 µm

20 µm 40 µm

AC/LTO = 4.17

AC/LTO = 1.54

AC/LTO = 0.72Key aspects

Carbon Carbon

+ -

+

+

+

+

+

+ --

-

-

--

- -

PF6-

Li+

+

Electrochemical Stability Window

Cycling stability Rate capability Electrochemical Impedance

Spectroscopy

Materials and combinations

Li4Ti5O12 (LTO) Li3V2-δNiδ(PO4)3 (LVNP) (δ =0, 0.05, 0.1)

poresActivated Carbon (AC)

- 2 -

Classical hybridization combining lithium insertion and DLC electrode

- 3 -

Li-ion capacitor based on Graphite and Activated Carbon

Li-ion capacitor based on LTO and Activated Carbon

Cericola et al. Journal of Power Sources 196 (2011) 10305-10313

“The LTO//AC hybrid do neither improve the battery nor the capacitor, because the specific energy is typically limited by the capacitor (AC) electrode and the specific power by the battery

(LTO) electrode.“

K. Naoi, S. Ishimoto, J-ichi Miyamoto and W. Naoi, Energy Environ. Sci, 5 (2012) 9363

How to balance a capacitor-type electrode with a battery-type electrode?

Classical balancing

Mass balancing between AC and LTO has to be made to

fully use both electrodes

The mass balancing is normally made based on the capacities obtained

at low C-rates

- 4 -

The mass balancing is not anymore valid at high currents!

0 50 100 150 200 250 300 350 400 450 500

1.2

1.5

1.8

2.1

2.4

2.7

3.0

3.3

3.6

3.9

4.2

4.5

0 10 20 30 40 50 60 70 80 90 100 110 120 130

0.9

1.2

1.5

1.8

2.1

2.4

2.7

3.0

3.3

3.6

3.9

4.2

4.5

0 1 2 3 4 5 6 7 8 9 10 11 12 13 140.30.60.91.21.51.82.12.42.73.03.33.63.94.24.5

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

AC/LTO 4.17 AC/LTO 1.54 AC/LTO 0.72

E / V

vs. L

i/Li+

time / s

cycle at 10 C

E / V

vs. L

i/Li+

time / s

cycle at 25 C

E / V

vs. L

i/Li+

time / s

cycle at 100 C

E / V

vs. L

i/Li+

time / s

cycle at 200 C

Our approach: modulation of AC/LTO mass ratio Effect of the AC/LTO mass ratio at high C-rate

20 µm 245 µm

AC/LTO = 4.17

20 µm 85 µm

AC/LTO = 1.54

20 µm 40 µm

AC/LTO = 0.72

S. Dsoke, B. Fuchs, E. Gucciardi and M. Wohlfahrt-Mehrens, J. of Power Sources, 282 (2015) 385-393 - 5 -

Classical balancing

100 1000 10000

1

10

100

AC//AC AC//LTO (ratio: 4.17) AC//LTO (ratio: 1.54) AC//LTO (ratio: 0.72)

Energ

y Den

sity /

Wh L

-1

Power Density / W L-1

1h10 min 60 sec

5 sec

1.5 sec

Energy-Power relationship Effect of the AC/LTO mass ratio

40 µm 40 µm

AC/AC = 1 Symmetric EDLC

20 µm 245 µm

AC/LTO = 4.17

20 µm 85 µm

AC/LTO = 1.54

20 µm 40 µm

AC/LTO = 0.72

S. Dsoke, B. Fuchs, E. Gucciardi and M. Wohlfahrt-Mehrens, J. of Power Sources, 282 (2015) 385-393 - 6 -

Decreasing the mass ratio AC/LTO leads to better high power performances • Smaller thickness of the AC cathode lower diffusion resistance • Intercalation degree of LTO anode influences the RCT • Improve the performance of an asymmetric device by simply optimizing the mass

ratios between cathode and anode.

0.335 Ω 0.436 Ω 1.23 Ω < < Charge transfer resistance

20 µm 40 µm

AC/LTO = 0.72

20 µm 85 µm

AC/LTO = 1.54

20 µm 245 µm

AC/LTO = 4.17[1] W. Lu et al. J. Electrochem. Soc. 154 (2007) A114-A118

Increase of RCT with intercalation degree in LTO electrodes also

observed by Lu et al. [1]

Effect of the AC/LTO mass ratio

COMPOSITE ANODECOMPOSITE CATHODE

Asymmetric-Hybrid Battery Supercapacitor

+ -



+ -



+ -



+ -

Containing Li-salt, necessary for the intercalation/deintercalation processes High ionic conductivity (low resistance), to enable high power

Stable in a broad voltage range where the materials are electrochemically active

Compatible with the electrode material used (activated carbon and Li-insertion materials)

Selection of electrolyte for asymmetric supercapacitor

Commercial (organic) electrolytes employed in EDLCs and LiBs

Salt: NEt4BF4

Solvent: ACN, PC

Salt: LiPF6, LiBF4, LiClO4

Solvents: mixture of alkil carbonates (EC, DMC, DEC…)

Examples: 1M NEt4BF4 in ACN

or 1M NEt4BF4 in PC

Examples: LiPF6 in EC:DMC (1:1)

or 1M LiPF6 in EC:DMC (7:1) various combinations

using a systematic approach - 9 -

(1): change of solvent (AN EC:DMC) factor of x3

(2): change of cation (NEt4+ Li+ in EC:DMC) factor of x3.3

(Li+ is strongly solvated, TEA+ is not)

(3): change of anion (BF4- PF6

- in EC:DMC) factor of ÷2

(4): difference between NEt4BF4 and LiPF6

(common salts for EDLC or LIB) "only" factor of ÷1.5

Electrochemical impedance response of symmetric AC//AC cells with various electrolyte combinations

Experimental setup: Symmetric Swagelock® cell 2 identical Activated Carbon electrodes (1.131cm2) 3 Separator (GFA) Activated Carbon: HDLC-20BST-UW from HayCarb

1M LiPF6 in EC:DMC (1:1) starting point for further investigations

T. Zhang, B. Fuchs, M. Secchiaroli, M. Wohlfahrt-Mehrens, S. Dsoke, Electrochimica Acta, 218 (2016) 163-173

0.8M LiPF6 + 0.2M Et4NBF4 in EC:DMC (1:1, wt.%)

0.8M LiPF6+ 0.2M Et4NBF4 in PC

1M LiPF6 in EC:DMC (1:1, w.t.%)

1M LiPF6 in PC

Li4Ti5O12 LiFePO4 Li3V2-xNix(PO4)3

ΔV: 2.8 V

Electrochemical stability window - compatibility AC-electrolyte -


0 10 20 30 40 50 60 70 80 90 1001.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 10 20 30 40 50 60 70 80 90 1001.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 10 20 30 40 50 60 70 80 90 1001.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 10 20 30 40 50 60 70 80 90 1001.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

E / V

vs. L

i/Li+

time/s

cycle 5 cycle 1000 cycle 8000 cycle 15000 cycle 20000

E / V

vs. L

i/Li+

time/s


E / V

vs. L

i/Li+

time/s


E / V

vs. L

i/Li+

time/s


Voltage profile evolution with cycling

ESW

ESW

LiPF6+NEt4BF4 in PC LiPF6 in PC

LiPF6+NEt4BF4 in EC-DMC LiPF6 in EC-DMC


Selection of electrolytes (interaction AC-electrolyte)

Electrolyte – AC interactions

Resistance

0 5 10 15 20 25 30 35 40 45 500

5

10

15

20

25

30

35

40

45

50

-Im(Z

)/Ohm

Re(Z)/Ohm

PC>EC-DMC

Cycling stability

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 2000002468

1012141618202224262830

Disc

harg

e cell

capa

citan

ce / F

g-1

cycle number

LiPF6 in EC-DMC LiPF6 + Et4NBF4 in EC-DMC LiPF6 in PC LiPF6 + Et4NBF4 in PC

superior stability of LiPF6 in PC

decomposition products at the PE induce degradation at the NE

modification of positive electrode surface (e.g. reducing the functional groups) may increase the stability and reduce the negative electrode aging

ESW 0.8M LiPF6 + 0.2M Et4NBF4

in EC:DMC (1:1, wt.%)

0.8M LiPF6+ 0.2M Et4NBF4 in PC

1M LiPF6 in EC:DMC (1:1, w.t.%)

1M LiPF6 in PC

LiPF6 in EC-DMC

LiPF6 Et4NBF4 in EC-DMC

LiPF6 Et4NBF4 in PC

LiPF6 in PC


Novel green tri-material negative electrode for high energy and power Lithium-ion supercapacitors

* M. Secchiaroli, G. Giuli, B. Fuchs, R. Marassi, M. Wohlfahrt-Mehrens, S. Dsoke, J. of Material Chemistry A, 3, (2015) 11807

Composition selection

Composition 1 Composition 2 Composition 3 Composition 40

10

20

30

40

50

60

70

80

% Active material

LTO

AC

AC

AC

AC

LTO

LTO

LTO

LVNP

/C

LVNP

/C

LVNP

/C

Acti

vated

mate

rials

% w

(comp

uted o

n a.m

. con

tent)

LVNP

/C0 20 40 60 80 100 120

0

20

40

60

80

100

120 LVNP/C:LTO:AC = 24:51:24 LVNP/C:LTO:AC = 51:24:24 LVNP/C:LTO:AC = 24:24:51 LVNP/C:LTO:AC = 33:33:33

0.16 0.32 0.8 1.6 3.2 6.4 9.6 16 24 32 0.32 0.16 A g-1

Spec

ific C

apac

ity / m

Ah g-1

Cycle number

Capacitor-type protocol

0 20 40 60 80 100 1200

20

40

60

80

100

120

0.16 0.32 0.8 1.6 3.2 6.4 9.6 16 24 32 0.32 0.16 A g-1

Spec

ific Li

de-in

s cap

acity

/ mAh

g-1

LVNP/C:LTO:AC = 24:51:24 LVNP/C:LTO:AC = 51:24:24 LVNP/C:LTO:AC = 24:24:51 LVNP/C:LTO:AC = 33:33:33

Cycle number

Battery-type protocol

0 20 40 60 80 100 1200

20

40

60

80

100

120

0.16 0.32 0.8 1.6 3.2 6.4 9.6 16 24 32 0.32 0.16 A g-1

LVNP/C:LTO:AC = 24:51:24 LVNP/C:LTO:AC = 51:24:24 LVNP/C:LTO:AC = 24:24:51 LVNP/C:LTO:AC = 33:33:33

Spec

ific C

apac

ity / m

Ah g-1

Cycle number

Hybrid-protocol

selected

compositions

10 wt%Binder Na-alginate Electrolyte: 1M LiPF6 in EC:DMC (1:1) - 15 -

Evaluation of full-asymmetric-hybrid systems

0.0 0.5 1.0 1.5 2.0 2.5

1.5

2.0

2.5

3.0

3.5

4.0

4.5

E / V

vs. L

i+ /Li

Time / h

Positive electrode Negative electrode

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Cell

Cell voltage / V

0.0 0.5 1.0 1.5 2.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

E / V

vs. L

i+ /Li

Time / h

Positive electrode Negative electrode

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Cell

Cell voltage / V

charge/discharge at 0.05 A g-1

double layer region

double layer region

selected tri-material

- 16 -

0.1 1 101

10

100

Spec

ific E

nerg

y / W

h kg-1

Specific Power / kW kg-1

Hybrid A Hybrid B LVNP II AC [1] AC II AC

1 h

6 min

1 min

14.4 s

3.6 s

0.01 0.1 1

10

100

Ener

gy D

ensit

y / W

h L-1

Power Density / kW L-1

Hybrid A Hybrid B LVNP II AC AC II AC

Evaluation of full-asymmetric-hybrid systems Ragone plots

Improved energy and power

- 17 -

[1] M. Secchiaroli, G. Giuli, B. Fuchs, R. Marassi, M. Wohlfahrt-Mehrens, S. Dsoke, J. of Material Chemistry A, 3, (2015) 11807-11816 M Secchiaroli, R Marassi, M Wohlfahrt-Mehrens, S Dsoke, Electrochimica Acta 219, (2016) 425-434

„New electrode design concept for hybrid battery supercapacitors“ (Novacap)

Acknowledgement

Emanuele Gucciardi Sonia Dsoke (Group Leader) Silvia Calcaterra Marco Secchiaroli Hai Yen Tran Kerstin Fischinger

Roberto Marassi

Financial support from German Federal Ministry of Education and Research (BMBF)

under the grant 03EK3021

- 18 -

Bettina Fuchs, Tong Zhang, Ann-Kathrin Huwer, Carmen Mäuser, Agnese Birrozzi Xu Tian

Documents

Materials selection for asymmetric/hybrid supercapacitorscii-resource.com/.../Wohlfahrt-Mehrens_Margret.pdf · M. Wohlfahrt-Mehrens . Materials selection for asymmetric/hybrid supercapacitors