Post on 26-Sep-2020
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!