Design the interface carbon materials &

its application in lithium ion capacitors

LI Feng (李峰)

Shenyang National Lab for Material Science

Institute of Metal Research, CAS

72 Wenhua Road, Shenyang, China

fli@imr.ac.cn

Outline

Carbon & Supercapacitor

Materials - From Design to High Energy

Cell - From Power to Function

Summary

Applications of electrochemical energystorage system (ES)2

(ES)2

H. D. Yoo, Materials Today, 2014. 17. 110-121

Requirement of Application

LIC

C. Zhong, Chemical Society Reviews. 2015, 44, 7485-7539

Larger energy capacity

Better safety

Longer life

Higher power capacity

Wider temperature range

Lithium ion capacitor (LIC)

Separator

Electrolyte

Active Materials : CarbonCurrent Collector

U

Configuration of LICs Cell

Anode & Cathode can be same

Advantage and disadvantages

A： D：

High energy > 20 Wh/kg

High Cell voltage > 4 V

Long Life

Low power(Graphite) Low capacitance(AC)

K. Naoi, Energy & Environmental Science. 2012, 5, 9363–9373

4.2-4.3 VLIC

Material Level Cell Level

Capacitance

Cycle

Material

Energy

Power

Capacitance

Cycle

System

Strategies to improve energy density

C: specific capacitance (F/g)

Q: specific capacity (mAh/g)

U: working voltage (V)

High-capacity materials High-voltage electrolytes

aqueousorganic

Energy density (E):

E : Number & potential

1.5V

4.5 V

0 V

4.5V

Our example:

Symmetric graphene SCs in LiPF6 /EC+DMC electrolyte:

Working voltage relies on the electrode potential window.

Common Phenomena after Assembly of LICs

Question & Solution

• How to bring electrode materials and electrolytes into full play in LIC devices?

From the Fact:C and U are determined on the potential window of

each individual electrode in LICs.

To Solution:Tuning electrode potential window (EPW).

Tuning initial electrode potential (E0V) to

optimize EPW of each individual electrode

Our Method

Why can EP be tuned?

For LICs, Electrode potential

(EP) depends on surface

charge density of electrode

materials.

Pote

ntia

l

the state of charge

Batteries

LICs

potential plateau

Batteries LICs

Mechanism ofenergy storage

Phase transformationin bulk

Surface double-layeradsorption,

Surface Faradic reaction

Free energy (G) −nFE (content) 1/2 CE2 =1/2 ΔQE (variable)

Our Approach

E0V

E’0V

Twographeneelectrodes

Discharged to 1.16V

0.01~1.16V20 cycles

ECI bygalvanostatic

charge/discharge

Postive electrode

Held at 1.16V for 2h

Held at 1.16V for 2h

Negative electrode

Process of Tuning EP

Assembledinto twohalf-cells

with Licounter

①

Disassemledfrom half cellsand assembled into a SC device

② ③

4.3V

Performance of LIC after Tuning EP

Graphene:

U & C are improved simultaneously.

Charge/discharge Curves of

graphene LIC at different

current densities

1C = 175 mA/g

Capacitance retention of

graphene before/after

tuning EP

fourfold

Performance of LIC after Tuning EP

Ragone Plot

63 Wh kg-1

at 11kW kg-1

Energy density improved by 10 Times！

152 Wh kg-1

Weng Z, Li F, et al, Angew. Chem. Int. Ed. 2013. A Hot Paper selected.

Cycle Stability after Tuning EP

Graphene SC SWCNT SC

91%75%

The last 20 cycles of graphene SLIC

4.73 V

0.42 V

E0V = 1.17 V

C of positive electrode decreases

4.3 V 4.3 V

? Why & What

0 100 2000

1

2

3

4

Pote

ntia

l (V

vs. L

i/Li+ )

Specific Capacity

Cathode

Anode

Reason for performance decay

Unstablewindow

OO

H

OO

H

O

OH

Electrolyte reduction

Byproducts

Cathode

1 2 3 4-0.6

-0.4

-0.2

0.0

0.2

Curre

nt (m

A)

Potential vs. Li/Li+

1st

10th5thChallenge:

To minimize electrolyte reduction

e-

e-

e-

e-

Graphene cathode

0 1 2 3 4 5 61

2

3

Volta

ge

Time (h) for PEC

Electrolyte with LiODFB

PEC Region(Protective layer formation)

Unstable window

Preliminary electrochemical coating (PEC)

1 2 3 4-0.6

-0.4

-0.2

0.0

0.2

Curre

nt (m

A)

Potential vs. Li/Li+

1st (reduction of LiODFB)

10th5th

Mechanism of PEC (Decomposition of LiODFB)

J. Electrochem. Soc., 156 (2009) A318

BF O C

ODFB-1

Li+

LiBC2O4F2 ≈ 1.7V

Ion- conductiveElectron -insulating

Twographeneelectrodes

Discharged to 1.16V

0.01~1.16V20 cycles

PEC+ ECI bygalvanostatic

charge/discharge

Postive electrode

Held at 1.16V for 2h

Held at 1.16V for 2h

Negative electrode

ECI bygalvanostatic

charge/discharge

NEW Process for Tuning EP

Assembledinto twohalf-cells

with Licounter

①

Disassemledfrom half cellsand assembled

into a LIC device

② ③

OO

H

OO

H

OH

OO

H

OO

H

O

OH

Electrolyte reduction

Armored graphene (A-G)

PEC

Byproducts

Graphene (G)

PEC

No electrons

Baymax Armed Baymax

What happen during PEC

XY Shan, F LI, et al, Adv Energy Mater, 2016: 1502064

0 100 200 300 4000

200

400

600 Fresh cell 10th cycle 50th cycle 100th cycle

-Z''

(ohm

)

Z' (ohm)

G PEC-G

(a) (b)

0 200 400 600 8000

200

400

600

800 Fresh cell 10th cycle 50th cycle 100th cycle

Z' (ohm)

-Z''

(ohm

)

EIS after Cycled

Original cathode After PEC

Increasing Stable

Electrochemical performance of A-GLISC

020406080

100120140160

5 10 20 30 50 100

GLISCA-GLISC

Spec

ific

capa

city

(mA

hg-

1)

Current density / C

0 400 800 12000

1

2

3

4

5

Volta

ge (V

)

Time (sec.)

5C 10C 20C 30C 50C 100C

102 103 104100

101

102

103

Ener

gy D

ensi

ty (W

h kg

-1)

Power Density (W kg-1)

Fe3O4/G//3D G

AG//Li4Ti5O12

AC//TiO2-RGO

AC//Li4Ti5O12

All-graphene battery

A-GLISC

GLISC

Li+ PF6-A

node

Cathode

- +

Anode

Cathode

- +

GLISC A-GLISC

PEC

G A-G-2G G

0 200 400 600 800 10000

30

60

90

120

150

180

Cycle number

Spec

ific

Cap

acity

(mA

hg-1)

Cou

lom

bic

effic

ienc

y (%

)

0

20

40

60

80

100

GLISCCoulombic efficiency of A-GLISC

A-GLISC

Coulombic efficiency of GLISC

0

20

40

60

80

100

Cap

acity

Ret

entio

n (%

)

80 %

Lithium storage systems

Decay of 0.011% per cycle

Highest retention among lithium ion

capacitors reported up to now.

Cycling stability of A-GLISC

Cycled GG

A-G-2 Cycled A-G-2

1µm

0

20

40

60

80

100

Ato

mic

Per

cent

age

(%) C

O F P

1µm

0

20

40

60

80

100

Ato

mic

Per

cent

age

(%) C

O F P

1µm

0

20

40

60

80

100

Ato

mic

Per

cent

age

(%) C

O F P

1µm

0

20

40

60

80

100

Ato

mic

Per

cent

age

(%) C

O F P

Results after cycled

P

Material Level Cell Level

Smart ?!

0 40 80 1200

2

4

Specific capacity (mAhg-1)

Volta

ge (V

) 4.3 V

SWCNTs-SLIC

Electrolyte limit

2.8 V

SWCNTs-SC

① ② ③

_On-lineECI

PE Charge

NEDischarge

Device

+

NE vs. Li discharge

PE vs. Li charge

Fulfill on-line ECI in device

2 um 10 nm

Electrode materials: SWCNTs

_

+

E’ovFull cell

Voltage modulator Energy boosting

High-Energy output

Integrate intelligence into LICs

👍👍 Monitor per electrode

👍👍 Built-in alerts for safety

👍👍 Self diagnosis & regeneration

Smart LICs --- Transparent Box

Charge DischargeSCs

Transparent Box

How to bring interactivity and autonomy into LICs?

+_ Smart device into SCs

Sensitive to internalchange inside SCs

V1V2

Feedback

Our strategy:

XY Shan, F Li et al, Energy storage materials 1:146-151 2015

Feedback Safety monitoring

0 50 100 1500.0

1.5

3.0

4.5

Specific capacity / mAhg-1

Pote

ntia

l vs.

Li/L

i+

Feedback:V1, V2: Voltage sensorsV1 alerts when < 0V;V2 alerts when > 4.5V

5 μm

Graphene

Ep-Max En-Min

Ep-Max

V2 alerts and device turns off!

Smart function

_

+> 4.5V Electrolyte

< 0V Li plating V1

V2

Feedback

Energyoutput

0 100 2000

50

100

150Po

tent

ial (V

vs. L

i+ /Li)

Spec

ific c

apac

ity (m

Ahg-1

)

Cycle number

Charge Discharge

0.1

0.2

0.3

4.4

4.6

Ep-Max

En-Min

Electrolyte limit

Cycle Capacity

Feedback + Voltage modulator Self-regeneration

0 100 200 300 3500

50

100

0

50

100

Cycle number

Coul

ombi

c Effi

cienc

y (%)

Spec

ific C

apac

ity (m

Ahg-1

)

G-SLIC G-SLIC-R

Discharge

Regeneration (G-SLIC-R)

Coulombic efficiency

0.875 1.750 2.6250

50

100

150

Capa

city

(mAh

g-1)

Current density (Ag-1)

G-SCG-SLICG-SLIC-R

Smart function

_

+> 4.5V Electrolyte

< 0V Li plating V1

V2

Feedback

① ② ③

_

PE Charge

NEDischarge

+

On-line ECI

V2 alerts and device turns off!

0 50 100 1500.0

1.5

3.0

4.5

Specific capacity / mAhg-1

Pote

ntia

l vs.

Li/L

i+ Ep-Max

Summary• Energy density of carbon based LICs are dependent

on working potential window after assembled to

LIC devices, which can be tuning.

• Optimization of potential window from materials to

cell design can attain LICs with high energy

density, long life & smart .

• Developing novel design and assemble technology

for LICs.

Acknowledgement

• NSFC

• MOST

• CAS

• Prof. Huiming Cheng @ IMR

• Dr. Xuyi Shan @ IMR

• Mr. Yuzuo Wang @IMR

• Dr. Ze Weng @ Yale, USA

• Dr. Dawei Wang @ NSW, Australia

• Prof. Zhangquan Peng @ CIAC, CAS

Thank you very much

for your attention!