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Future battery chemistries –the rôle of sodiumA. Robert ArmstrongA. Robert Armstrong
EaStCHEM, School of Chemistry, University of St Andrews, St. Andrews, UK
•Why sodium?•Comparison of sodium ion vs lithium ion
•Similarities and differences•Negative electrodes
•Oxides•Alloys•Organics
•Positive electrodes•Polyoxyanions•Layered materials
More important today than at any time in historyOutils portatifsOutils portatifs
Power tools
Energy storageEnergy storage
Medical applicationsImplantable batteryImplantable battery
Artificial heartArtificial heart
Portable electronics
Sola
rW
ave
Win
d
Electricity generation Renewables
IntermittentIntermittent
Nuclear
ContinuousContinuous
Electrificationof transport
Electric Plug-inPlug-inHybridHybrid
Sodium-ion BatteriesSodium-ion Batteries
Much interest due to •low cost •potential for grid scale application
From Li-ion to Na-ion BatteriesFrom Li-ion to Na-ion BatteriesVast market for Lithium-Ion Batteries
Lithium resources unevenly distributedMost in Andes (Chile, Bolivia)
NEED TO FIND ALTERNATIVES
• Li and Na: alkali metals
• Abundance on Earth:- Li: 25th r(Li+) = 67 pm- Na: 4th r(Na+) = 97 pm
Similar propertiesNa is low-cost but heavier molecular weight NIBs for static energy storage systems
Na and Li similar but different!Na and Li similar but different!Positive electrodes
Sodium compounds have stronger tendency to adopt layered structures (larger ionic radius)Lithium mostly octahedral coordination (tetrahedral in spinel)Sodium trigonal prismatic coordination (some octahedral)
Leads to different stacking sequences
O3 P2
Na(Cr/Fe)O2Li(Cr/Fe)O2
Na and Li similar but different!Na and Li similar but different!
Na compounds electrochemically active unlike their Li equivalents
S. Komaba et al., Electrochem. Comm. 12, 2010, 355
Positive electrodes
Na and Li similar but different!Na and Li similar but different!
Negative electrodes
Cannot use graphite as negative electrode – negligible sodium intercalation (below 0V)
Can insert/extract Na in amorphous hard carbonCheap (e.g. from pyrolysis of sugar)
Negative electrodes for Na-ionNegative electrodes for Na-ion• Unlike lithium Na does not form alloys with aluminium • No need for heavy, more expensive copper current collector
Hard carbon favoured at present but no clear favourite
Na2Ti3O7 – remarkably low voltage but poor capacity retention
Negative electrodes for Na-ionNegative electrodes for Na-ion
AlloysTin works well despite v. large volume change
Komaba et al. Electrochemistry Communications 21 (2012) 65–68
J. W. Wang, X. H. Liu, S. X. Mao and J. Y. Huang, Nano Lett., 2012, 12, 5897–5902
Negative electrodes for Na-ionNegative electrodes for Na-ion
Organics
Conjugated dicarboxylates e.g. terephthalateAvailable from biomass/recycling
Park et al. Adv. Mater. 2012, 24, 3562–3567
0 20 40 60 80 100 120 140 160 180 2000
50
100
150
200
250
Dis
char
ge c
apac
ity /
mA
hg-1
Cycle number
100 mA/g 400 mA/g
promising activity Capacity around 200 mAhg-1 at ~ 0.5 V vs. Na+/Na
Sodium 2,6 naphthalene dicarboxylate Sodium 2,6 naphthalene dicarboxylate
Positive electrodes for Na-ionPositive electrodes for Na-ion
Vanadium phosphates offer high voltage/good rate capability
Gover, R. K. B.; Bryan, A.; Burns, P.; Barker, J. Solid State Ionics 2006, 177, 1495
Ponrouch et al. Energy Environ. Sci., 2013,6, 2361-2369 DOI: 10.1039/C3EE41379A
Strong similarities with Li-ionSodium transition metal oxides and polyanionic systems
Polyanions
Positive electrodes for Na-ionPositive electrodes for Na-ionAs with Li-ion materials sulphates give high voltages
Prabeer Barpanda, Gosuke Oyama, Shin-ichi Nishimura, Sai-Cheong Chung & Atsuo YamadaNature Communications 5, Article number: 4358 doi:10.1038/ncomms5358
Na2Fe2(SO4)3
Positive electrodes for Na-ionPositive electrodes for Na-ionLayered compoundsHave access to Fe3+/Fe4+ couple not possible for LiNax[Fe1/2Mn1/2]O2 with P2 structure benchmark material
N. Yabuuchi, M. Kajiyama, J. Iwatate, H. Nishikawa, S. Hitomi, R.Okuyama, R. Usui, Y. Yamada and S. Komaba, Nat. Mater., 2012, 11, 512–517
Pros: Fe and Mn cheap and safe, high capacityCons: wide voltage range, significant fade, made with x = 0.67
Layered compoundsCan show MANY phase transitions
Jahn-Teller distortion and charge ordering
-120 -100 -80 -60 -40 -20 0 20 40
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
Pote
ntia
l / V
dQ / mAhg-1
-140 -120 -100 -80 -60 -40 -20 0 20
2.0
2.5
3.0
3.5
4.0
4.5
Na2/3(Mn,Ni)O22-4.3 V 10 mA/g 1M NaPF6 in PC 5% FEC
cycle 1 cycle 2 cycle 3 cycle 4 cycle 5 cycle 10 cycle 20
Pot
entia
l (V
)
dQ (mAh/g)
P2-O2 transition at high potentialShearing of layers
Use substitutions to remove transitions
-50050100
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Volta
ge (V
)
Na0.67Mn0.95Mg0.05O2
Capacity (mAh/g)
P2 Nax(Mn,Ni,Li)O2 P2 Nax(Mn,Ni)O2
Advanced Energy Materials1, 333-336, 2011 DOI: 10.1002/aenm.201000061
P2 NaxMnO2 P2 NaxMn1-yMgyO2
0 10 20 300
20
40
60
80
100
120
140
160
180
Disc
harg
e Cap
acity
/ m
Ahg-1
Cycle number
5% Mg undoped
Improved stability compared with undoped material
0 5 10 15 20 250
50
100
150
200
250
Discharge Capacity Charge Capacity
Cycle Number
Capa
city
(mAh
/g)
20% Mg (slow cooled) very stable at low rate
-100 -50 0 50 100 1501.5
2.0
2.5
3.0
3.5
4.0
Volta
ge (V
vs.
Na+ /N
a)
Capacity (mAh/g)
x = 0x = 0.05x = 0.1x = 0.2
Structural Characterisation
20 40 60 80
2 / FeK1
x=0
x=0.05
x=0.1
OP4
P2
P2-OP4 transition disappears with increasing amount of Mg
0 70 140
3.0
3.6
4.2
Volta
ge (V
vs.
Na+ /N
a)
Capacity (mAh/g)
x = 0x = 0.05x = 0.1x = 0.2
0 10 20 30 40 50 60 70 80 90 1000
20
40
60
80
100
120
140
160
180 Na0.67
Mn0.95
Mg0.05
O2 quenched
Dis
char
ge c
apac
ity /
mA
h/g
Cycle number
50 mA/g 500 mA/g
Constant currentConstant current
0 10 20 30 40 50 60 70 80 900
20
40
60
80
100
120
140
160
180 Na0.67
Mn0.95
Mg0.05
O2 quenched
Dis
char
ge c
apac
ity /
mA
h/g
Cycle number
100 mA/g 1000 mA/g
Slow charge – fast dischargeSlow charge – fast discharge
Positive electrodes for Na-ionPositive electrodes for Na-ion
-NaMnO2
0 20 40 600
50
100
150
200
C/2 C/20
C/20
10C4C
2C
C
C/4
Spec
ific
Dis
char
ge C
apac
ity (m
Ah/
g)
Cycle Number
SummarySummary
• Sodium-ion chemistry has many similarities with lithium-ion
• Some unique features giving rise to attractive properties e.g.
Fe3+/Fe4+
• No need for copper current collector
• Low cost
• Performance can even rival Li-ion
AcknowledgmentsAcknowledgments