lithium metal phosphates as cathode materials ... - aventri
TRANSCRIPT
- 1 -
Conférence internationale sur les olivines pour batteries rechargeables OREBA 1.0
In Honor of Dr. Michel Armand Montréal, May 25 – 28 2014
Margret Wohlfahrt-Mehrens
Zentrum für Sonnenenergie- und Wasserstoff-Forschung (ZSW) Baden-Württemberg
Lithium Metal Phosphates as Cathode Materials for Li-Ion Batteries
Status and Future Perspectives
Lithium Metal Phosphates as Cathode Materials for Li-Ion Batteries
non toxic low-cost raw materials Lower operating voltage, higher stability of electrolytes high thermal stability in the lithiated and delithiated state not a classical electrode material: • Low electronic conductivity LiFePO4 • Low ionic conductivity • two-phase reaction phase boundary migration • limited rate capability
Triphilite LiFePO4 http://www.mindat.org/photo-202039.html
LiFePO4 FePO4 + Li+ + e-chargedischarge
Padhi, A.K., Nanjundaswamy, K.S., Goodenough, J.B. Journal of the Electrochemical Society, 144 (4), 1997, 1188-1194.
Lithium Metal Phosphates as Cathode Materials for Li-Ion Batteries
Approaches to solve these problems composition and structural level nanosized material or nanostructured material building a conductive surface network - “carbon painting” Ravet, N., Chouinard, Y., Magnan,J.F., Besner, S., Gauthier, M., Armand, M., Journal of Power Sources, 97-98, 2001, 503-507N.
LiMe(II)PO4 Me(III)PO4 + Li+ + e- charge
discharge
LiFePO4 Li+ + FePO4 + e−LiFePO4 Li+ + FePO4 + e−
LiFePO4 Li+ + FePO4 + e−LiFePO4 Li+ + FePO4 + e−
Li M P O
Lithium Metal Phosphates as Cathode Materials for Li-Ion Batteries - today
inherent safe, long life, high power material
Applications • Low voltage applications • E-bikes • Hybrid electric vehicles • Electric vehicles • Stationary applications
• 2010 – 2014 more than 1.000 scientific publications
• initiated research on other polyanion material classes
0 3000 6000 9000 12000 150000
20
40
60
80
100
C
apac
ity /
%
Cycle number
- 5 -
Excellent Cycling Life 18650 cell Amorphous carbon//LFP
70 Wh/kg
Charge/Discharge 2C (CC)
2 – 3,6 V
Higher Safety of LFP Compared to Layered Oxides
Thermal Abuse Test
• LFP 18650 cell: Hazard level 3 (no thermal runaway)
• NMC 18650 cell: Hazard level 4 (thermal runaway)
LFP NMC
100 110 120 130 140 150 160 170 180 190 200 2100,0
0,5
1,0
1,5
2,0
Hea
t Rat
e [°
C/m
in]
Temperature [°C]
100 110 120 130 140 150 160 170 180
0,02
0,04
0,06
0,08
ARC
• LFP cell: self heating is lower and shifted to higher temperature
LFP cell is more safe
Excellent Safety Compared to Layered Oxides
100 150 200 250 300 350
0,01
0,1
1
10
100
1000
SR
H [°
C/m
in]
Temperature [°C]100 150 200 250 300 350
0,01
0,1
1
10
100
1000
S
HR
[°C
/min
]
Temperature [°C]
100% SOC 30% SOC 10% SOC
100% SOC 30% SOC 10% SOC
NMC LFP
0,1
1
10
100
1000
10 30 100
SOC [%]
SHR
[°C
/min
]
0
500
1000
1500
2000
2500
Gas
Evo
lutio
n [m
l]
self-heating rate
gas evolution
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1
10 30 100
SOC [%]
SHR
[°C
/min
]
0
500
1000
1500
2000
2500
Gas
Evo
lutio
n [m
l]
self-heating rate
gas evolution
LFP
NMC
0 1000 2000 3000 4000 5000 60000
20
40
60
80
100
C
apac
ity /
%
Cycle number
Routes to improve energy density: LFP//NMC Blends
0,0 0,5 1,0 1,5
0
1
2
3
4
5
Full cell Cathode Anode
Time / h
Full
cell
volta
ge /
V
and
cath
ode
pote
ntia
l / V
vs.
Li/L
i+
0,0
0,5
1,0
1,5
2,0
Anode potential / V
vs. Li/Li +
5760 cycles > 95%
NCM/LFP blend 3:1; 93% AM/ 3% CB/ 1% Gr/ 3% binder Loading: 14 mg cm-2; electrolyte EC:EMC (3:7) + 2 wt. % VC
0,0 0,5 1,0 1,5
0
1
2
3
4
5
Full cell Cathode Anode
Time / h
Full
cell
volta
ge /
V
and
cath
ode
pote
ntia
l / V
vs.
Li/L
i+
0,0
0,5
1,0
1,5
2,0
Anode potential / V vs. Li/Li +
100 150 200 250 300 350
0,01
0,1
1
10
100
1000
NMC
NMC
Blend
Blend
Temperature / °C
SH
R /
°C*m
in-1
0,0 0,5 1,0 1,5
0
1
2
3
4
5
Full cell Cathode Anode
Time / h
Full
cell
volta
ge /
V
and
cath
ode
pote
ntia
l / V
vs.
Li/L
i+
0,0
0,5
1,0
1,5
2,0
Anode potential / V vs. Li/Li +
Routes to improve energy density: LFP//NMC Blends
Charged/discharged C/5 between 3,0and 4,2 V 50 cycles 1 C CC/CD room temperature Charged C/10 to 4,2 V Maximum self heating rate NMC: 280°Cmin-1 Blend: 18°Cmin-1
From LiFePO4 to higher voltage LiMePO4 (M: Mn, Co, Ni)
130
320
145
356
187
452
010
020
030
040
050
0
spec
ific
ener
gy W
h/kg
// e
nerg
y de
nsity
Wh/
l
LFP LMP LCP
specific energy Wh/kgenergy density Wh/l
Baseline LFP 18650 cell Projected specific energy for 18650 cells assuming comparable specific capacity for manganese and cobalt based materials
• higher energy density compared to LFP based cells • reduce the energy density gap to layered lithium metal oxides • increased abuse tolerance compared to layered oxides • LCP higher capacity compared to LMNO
From LiFePO4 to LiMePO4 Me = Mn, Co Challenges and strategies
• low electronic conductivity LiMnPO4 << LiFePO4 nanosize particles and carbon coating • strain between charged and discharged state (lattice mismatch)
LiFePO4/FePO4 6,6% LiCoPO4/CoPO4 7,1% (intermediate phase LixCoPO4 reported)* LiMnPO4/MnPO4 9,0% generation of Jahn-Teller ion Mn3+
• instability of the delithiated states Mn(III)PO4** and Co(III)PO4 ** LiM(1)xM(2)1-xPO4 or LiM(1)xM(2)yM(3)1-x-yPO4 for longer cycling life
• low electrolyte stability N.N. Bramnik, K. Nikolowski, D. M.Trots, H. Ehrenberg,. Electrochemical and Solid-State Letters, 2008, 11, A89.*
S.–W. Kim., J. Kim., H. Gwon., K. Kang., J. Electrochem. Soc. 2009, 156(8), A635–A38.** L. Wang, F. Zhou, G. Ceder, Electrochem. Solid–State Lett. 2008, 11(6), A94–A96.** G. Hautier, A. Jain, S. Ong, B. Kang, C., R. Doe, G. Ceder, Chem. Mater. 2011, 23, 3495–3508**
From LiFePO4 to LiMePO4 Me = Mn, Co Challenges and strategies
LiM(1)xM(2)1-xPO4 or LiM(1)xM(2)yM(3)1-x-yPO4 for longer cycling life
3000
3500
4000
4500
5000
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1y in LiyMnxFe1-xPO4
pote
ntia
l / m
V
LiMn0.5Fe0.5PO4LiMn0.9Fe0.10PO4LiFePO4
LiMnxFe1-xPO4x = 0.0x = 0.5x = 0.9
3000
3500
4000
4500
5000
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1y in LiyMnxFe1-xPO4
pote
ntia
l / m
V
LiMn0.5Fe0.5PO4LiMn0.9Fe0.10PO4LiFePO4
LiMnxFe1-xPO4x = 0.0x = 0.5x = 0.9
solid–solution series LiMnyFe1–yPO4*, high power LiMn0.8Fe0.2PO4*
A.Yamada, S.C. Chung, J. Electrochem. Soc. 2001, 148(8), A960–A967, A. Yamada,Y. Kudo, K.–Y. Liu, J. Electrochem. Soc. 2001, 148(7), A747–A754
D. Aurbach et al. Angewandte Chemie, 2009, 121(45), 711-715
Mixed phospho olivines to compensate structural changes
Unit cell volumes of the Phospho-Olivine Phases change in the series: Mn > Fe > Co > Mg > Ni Large difference between LiMgPO4 and LiMnPO4
→ strong influence of substitution expected
Lithiated state:
solid solution of LiMnIIPO4 und LiMgIIPO4
Delithiated state –
solid solution of MnIIIPO4 and LiMgIIPO4
Δ V = 7.5%
Δ V = 3.7%
Δ V = 2.4%
Δ V = 3.5%
unit
cell
volu
me
[Å]
250 260 270 280 290 300 310
LiMnPO4 LiFePO4 LiCoPO4 LiMgPO4
Expected influence of partial substitution Consequences: smaller ΔV between charged and discharged phase → lower lattice mismatch → reduced strain at phase boundary decreasing amount of Mn(III) d4 → stabilisation of delithiated phase 1 Lithium per formula unit → lower lattice mismatch → reduced strain at phase boundary → mixed valent regions, solid solution regions
270
280
290
300
310
0,0 0,5 1,0x in LiMgxMn1-xPO4
Uni
t cel
l vol
ume
[A3]
for
solid
sol
utio
n
LMPMPlithiated state
delithiated state
Δ V
270
280
290
300
310
0,0 0,5 1,0x in LiMgxMn1-xPO4
Uni
t cel
l vol
ume
[A3]
for
solid
sol
utio
n
LMPMPlithiated state
delithiated state
Δ V
260
265
270
275
280
285
290
295
300
305
0.0 0.2 0.4 0.6 0.8 1.0x in Liy(Co1-xMnx)PO4
Ele
men
tarz
ellv
olum
en b
erec
hnet
LiCo1-xMnxPO4Li1-xCo1-xMnxPO4Co1-xMnxPO4Δ V I → II
Δ V II → III
Uni
t cel
l vol
ume
calc
ulat
ed
260
265
270
275
280
285
290
295
300
305
0.0 0.2 0.4 0.6 0.8 1.0x in Liy(Co1-xMnx)PO4
Ele
men
tarz
ellv
olum
en b
erec
hnet
LiCo1-xMnxPO4Li1-xCo1-xMnxPO4Co1-xMnxPO4Δ V I → II
Δ V II → III
260
265
270
275
280
285
290
295
300
305
0.0 0.2 0.4 0.6 0.8 1.0x in Liy(Co1-xMnx)PO4
Ele
men
tarz
ellv
olum
en b
erec
hnet
LiCo1-xMnxPO4Li1-xCo1-xMnxPO4Co1-xMnxPO4Δ V I → II
Δ V II → III
Uni
t cel
l vol
ume
calc
ulat
ed
Dynamic stability – electrochemical active M ΔV LMP/MP example Co-Mn
Step I: LiMn(II)0.5Co(II)0.5PO4 → Li0.5Mn(III)0.5Co(II)0.5PO4 + 0.5Li+ + 0.5e-
Phase I Phase II
Step II: Li0.5Mn(III)0.5Co(II)0.5PO4 → Mn(III)0.5Co(III)0.5PO4 + 0.5Li+ + 0.5e-
Phase II Phase III
Phase I Phase II Phase III
Phase I + Phase II Phase II + Phase III
ΔV I → II Δ V II → III
Effect of partial substitution on potential
LiMnPO4
2900
3100
3300
3500
3700
3900
4100
4300
4500
4700
4900
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
x in LixMnPO4
Pote
ntia
l / m
V
LiMnPO4
LiMg0.12Mn0.88PO4
Positive potential shift ~ 150 mV
132 mAh g-1
146 mAh g-1
LiMnPO4
2900
3100
3300
3500
3700
3900
4100
4300
4500
4700
4900
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
x in LixMnPO4
Pote
ntia
l / m
V
LiMnPO4
LiMg0.12Mn0.88PO4
Positive potential shift ~ 150 mV
132 mAh g-1
146 mAh g-1
2900
3400
3900
4400
4900
0 0,2 0,4 0,6 0,8 1y in LiyMgxFe1-xPO4
Pote
ntia
l [m
V]
LiMg0.07Mn0.83Fe0.1PO4161mAh g-1
LiMn0.5Fe0.5PO4160 mAh g-1
2900
3400
3900
4400
4900
0 0,2 0,4 0,6 0,8 1y in LiyMgxFe1-xPO4
Pote
ntia
l [m
V]
LiMg0.07Mn0.83Fe0.1PO4161mAh g-1
LiMn0.5Fe0.5PO4160 mAh g-1
LiMg0.07Mn0.83Fe0.1PO4161mAh g-1
LiMn0.5Fe0.5PO4160 mAh g-1
Mn
Fe
Co Mg (Ni, Zn)
Mn
Fe
Co Mg (Ni, Zn)
No interaction
Potential shift
• Mg shifts Mn plateau to more positive values • no influence on Fe plateau
Higher Oxidation States of Manganese in the Olivine Structure?
• Li:M ratio restricts the redox-chemistry in olivines to M(II)-(III) step
• partial substitution of Manganese fixes Li+ in the charged olivine
structure
• in LiMnPO4, LiFePO4 and LiMnxFe1-XPO4 with and without Mg
M(II) → M(III) Li[MgII
xMnII1-x]PO4 → Lix[MgII
xMnIII1-x]PO4 + (1-x) Li+ + (1-x) e-
M(III) → M(IV) Lix[MgII
xMnIII1-x]PO4 → [MgII
xMnIVxMnIII
1-2x]PO4 + x Li+ + x e-
First discharge profile after charging to 5.3 V LMP - 7% Mg and 12%Mg
3000
3500
4000
4500
5000
5500
0 5 10 15 20 25 30
spezifische Kapazität mAh/g
Ent
lade
pote
ntia
l vs
Li/L
i+ / m
V
LMP-G18-T1 5.3 VLMP-G18-T1 5.3 VLMP-G19-T1 5.2 VLMP-G19-T1 5.2 VLMP-G18-T1 4.9 VLMP-G19-T1 4.9 V
12% Mg to 4.9 V to 5.3 V
7% Mg to 4.9 V to 5.3 V
Specific capacity [mAh/g]
Pot
entia
l vs
Li/L
i+ [
mV
]
Mn(III) → Mn(IV) + e- ?
additional potential plateau at 4.8 V !
Length depends on Mg(II) content !
Not observed for Mg substituted LFP
Formal oxidation states and electronic configurations
FeII MnII
d6 d5
FeIII MnII
d5 d5
FeIII MnIII
d5 d4
FeIV MnIII
d4 d4FeIII MnIV
d5 d3
step I
step II
step III
Li[MgxFeyMn1-x-y]PO4
Li1-y[MgxFeyMn1-x-y]PO4
Lix[MgxFeyMn1-x-y]PO4
[MgxFeyMn1-x-y]PO4
FeII MnII
d6 d5
FeIII MnII
d5 d5
FeIII MnIII
d5 d4
FeIV MnIII
d4 d4FeIII MnIV
d5 d3
FeII MnII
d6 d5
FeIII MnII
d5 d5
FeIII MnIII
d5 d4
FeIV MnIII
d4 d4FeIV MnIII
d4 d4FeIII MnIV
d5 d3FeIII MnIV
d5 d3
step I
step II
step III
Li[MgxFeyMn1-x-y]PO4
Li1-y[MgxFeyMn1-x-y]PO4
Lix[MgxFeyMn1-x-y]PO4
[MgxFeyMn1-x-y]PO4
Symmetric configurations
stabilisation of the structure
Jahn-Teller-Ions
distortion destabilisation‘ of structure
Influence of powder morphology
Li(MnFe)PO4 cycling stability
Button Cell Capacity Curves
0
20
40
60
80
100
120
140
160
0 50 100 150 200Cycle Number
Spec
ific
Cap
acity
(mAh
/g)
05-05-E05-06E06-05E06-06E07-04E07-05E07-06E08-04E08-05E10-04-E11-03-E12-03-E
Voltage range 2,5V - 4,3V, C/5 CCCV ; 1C Discharge; active mass > 92%
- 22 -
High voltage LiCoPO4 different states of charge
no exothermic reaction until the second plateau
⇒ LizCoPO4 thermal stable
⇒ exothermic decomposition of CoPO4
Enthalpy Peak B
[J/g]
Mass loss – 270°C [%]
uncharged - 0,2
24 mAh/g - 0,2
50 mAh/g - 0,3
74 mAh/g 50 0,8
120 mAh/g 79 1,0
140 mAh/g 117 1,4
Charged 163 2,4
LiCoPO4
⇓
LizCoPO4
LizCoPO4
⇓
CoPO4
0.00
0.05
0.10
0.15
0.20
0.25
0 5 10 15 20 25x in LiCo1-xMxPO4
hyst
eres
es s
tep
1 an
d 2
[V
]
Mg C1-D1Mg C2-D2Ni C1-D1Ni C2-D2Fe C2-D2Fe C1-D1
Influence of partial substitution of Co by Ni, Mg or Fe on the hysteresis of LiCoPO4
Ni
Mg Fe
-150
-100
-50
0
50
100
150
200
250
4300 4500 4700 4900 5100 5300
Potential vs Li/Li+ [mV]
dQ/d
E
C1
C2
D1
D2
Influence of electrolyte
• Standard electrolyte without additives
• High initial capacity, high capacity fading
• Optimized high voltage electrolyte plus additives
• Lower initial capacity, higher cycling stability
156 mAh/g
Optimised electrolyte solution
E. Markevich, R. Sharabi, H. Gottlieb, V. Borgel, K. Fridman, G. Salitra, D. Aurbach, G. Semrau, M.A. Schmidt, N. Schall, C. Bruenig, Electrochemistry Communications 15 (2012), pp 22-25
Calculated Energy Density of Mixed Phosphates From Measured Data
3,4 3,6 3,8 4,0 4,2 4,4 4,6 4,8 5,0110
120
130
140
150
160
170
180
LiCoPO4
LiCo0.70Mn0.15Fe0.15PO4
LiCo2/3Fe1/3PO4
LiCo1/2Mn1/2PO4
LiCo1/3Mn1/3Fe1/3PO4
LiNi0.80Co0.15Al0.05O2
LiFePO4
LiCoPO4
LiCo0.70Mn0.15Fe0.15PO4
LiCo2/3Fe1/3PO4
LiCo1/2Mn1/2PO4
LiCo1/3Mn1/3Fe1/3PO4
LiNi0.80Co0.15Al0.05O2
LiFePO4
Energy threshold NCA(refered to cathode mass only)
Rev
ersi
ble
Cap
acity
/ m
Ah/
g
Average Discharge Potential / V vs. Li/Li+
Energy threshold NCA(refered to mass of cathode and anode)
Summary
• LFP well established safe and long life electrode material
• Lithium mixed metal phosphates are promising as high voltage cathode materials
• Partial substitution of Mn by other metals leads to higher stability and performance
• Mixed Lithium Manganese Cobalt phosphates can give similar or even higher specific energy
compared with layered oxides and higher safety
• Progressing studies of the underlying charge/discharge mechanism will lead to a deeper
understanding
• Adjustment of composition and structure, selection of proper cell components as binder,
separator, electrolyte will lead to further breakthroughs for the high voltage materials
• Thanks to John Goodenough and Michel Armand research directions have been
opened for new classes of materials
Peter Axmann Michaela Memm Melanie Köntje Gisela Arnold Reinhard Hemmer Wolfgang Weirather Mario Wachtler Gerda Dörfner Meike Fleischhammer Gunther Bisle
Acknowledgements
“Funktionsmaterialien und Materialanalytik zu Lithium–Hochleistungsbatterien“ WO882/4–1
BASTA
- 29 - Stuttgart Photovoltaics & Solab Energy Policy & Energy Carriers
Widderstall Solar test-field
Ulm Electrochemical Energy Technologies
Thank you for your attention!
[email protected] www.zsw-bw.de
Zentrum für Sonnenenergie- und Wasserstoff-Forschung
Baden-Württemberg Helmholtzstraße 8, 89081 Ulm
Ulm eLab Center for battery research
100 200 300 400 500
-0,9
-0,8
-0,7
-0,6
-0,5
-0,4
-0,3
-0,2
-0,1
0,0
0,1
DS
C [m
W/m
g]
Temperature [°C]
0
5
10
15
20
25
m/z
= 32
and
44,
Ion
curr
ent [
10-1
0 A]
100 200 300 400 500
-0,4
-0,3
-0,2
-0,1
0,0
0,1
0,2
0,3
DS
C [m
W/m
g]
Temperature [°C]
0,00
0,02
0,04
0,06
0,08
0,10
m/z
= 32
and
44,
Ion
curr
ent [
10-1
0 A]
High-Voltage LiMnPO4: Effect of Doping
A
B
exo.
CO2 (m/z=44)
O2 (m/z=32)
C
A
B
CO2 (m/z=44)
O2 (m/z=32)
C 4,8V 4,8V
• Exothermic Reaction B: 335°C • CO2-Formation: 335°C • No O2-Formation
Heat formation decreases
LiMnPO4 Mg-doped LiMnPO4
Electrolyte: 1Mol LiPF6 EC:DMC= 1:1
37J/g
19J/g
• Chemical composition • Crystal structure • Doping • SEI stability
Thermal Stability of Fully Charged Cathode Materials From Layered Structure to Olivine
100 200 300 400 500
-0,1
0,0
0,1
0,2
0,3
0,4
0,5
DS
C [m
W/m
g]
Temperature [°C]
2,0
2,5
3,0
3,5
4,0
4,5
5,0
5,5
6,0
m/z
= 32
, Ion
cur
rent
[10-1
0 A]
A
B
A
C
Li(Ni1/3Mn1/3Co1/3)O2 (NMC) LiFePO4 (LFP) 4,3V 4,2V
exo.
• Exothermic Reaction: 250-500°C • O2-Formation: 300°C Structural changes:
R-3m-type → NiO-type + O2
• Only small Exothermic Reaction: 470°C • CO2-Formation: 470°C (→ binder reaction) • No O2-Formation
CO2 (m/z=44)
O2 (m/z=32) O2 (m/z=32)
100 200 300 400 500
-0,9
-0,8
-0,7
-0,6
-0,5
-0,4
-0,3
-0,2
-0,1
0,0
DS
C [m
W/m
g]Temperature [°C]
5
10
15
20
25
30
m/z
= 32
and
44,
Ion
curr
ent [
10-1
0 A]
Electrolyte: 1Mol LiPF6 EC:DMC= 1:1
0
20
40
60
80
100
0 2000 4000 6000 8000 10000 12000Cycle
rela
tive
Capa
city
[% o
f ini
tial]
- 32 -
Excellent Cycling Life 18650 cell Amorphous carbon//LFP
70 Wh/kg
Charge/Discharge 2C (CC)
2 – 3,6 V