M. Rosa Palacín

ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Barcelona) SPAIN rosa.palacin@icmab.es

Battery energy storage

beyond Li-ion

?

Volta 1792-94

Volta 1801

Planté 1859 Jungner 1899 - +

LiyC LixCoO2e-

Introduction

R. Brodd, ATP Working Paper Series Working Paper 05–01, NIST (US)

10-19!!!

Cost

Safety

Energydensity

Increasingsize

Application Sustainability

energy / water footprint

recycling

critical vs. abundant materials

Performance

Tarascon & Armand, Nature 414 (2001) 359

41000 Wh

~ x 10

~ x 620

~ x 5900

… and larger if grid applications are considered !!!

Growing larger….

www.crugroup.com

Price of Li2CO3 over time (US$/ton)

M-ion concept

analogous to Li-ion Mn+ as charge carriers instead of Li+

(migration may be an issue for n>1, coulombic interactions)

energy density not directly related to M (but to electrode material capacities & potentials)

Na-ion

M-anode concept

0

1000

2000

3000

4000

5000

0

2000

4000

6000

8000

10000

Li C Na Mg Al Ca

Gravim

etric capacity (mA

h/g)Volu

met

ric c

apac

ity (m

Ah/

cm3 )

Li-ion

Li “unsafe” ? polymer electrolyte ? air or sulphur cathodes?

Na low melting T, “unsafe” as solid?

Na/S successful (liquid electrodes) Mg electrolytes with wide V window?

high energy density cathodes? Ca interesting potential reversible plating/stripping? Al lower potential

reversible plating/stripping?

Na-ion batteries

à “unlimited” Na resources 20 ppm 22700 ppm Earth’s crust

à high standard reduction potential -3.04 -2.71 vs. NHE

à alloy formation with Al yes no

Current collector (Al)

Active material

Additive

Binder

Separator

SEI

Electrode

material

--++

Current collector (Cu)

Additive

Binder

Li-ion Na-ion

à Similar chemistry

- Faster progress à Differences

  - Ionic radius – coordination – crystal chemistry

  - Polarizing character – diffusion – kinetics

  - Solvation energy – solubilities – SEI

Graphite // LiPF6 EC:DMC // LiFePO4

Graphite // NaPF6 EC:DMC // NaFePO4

Alike but different…

Practical prospects

Na15Pb4 || NaxCoO2

100 ºC

th: 350 Wh/kg, 1470 Wh/l

P(EO)8NaCF3SO3

1M NaPF6 in DME

Practical prospects

Na15Pb4 || NaxCoO2

100 ºC

th: 350 Wh/kg, 1470 Wh/l

P(EO)8NaCF3SO3

1M NaPF6 in DME

N. Yabuuchi et al. Chem. Rev. 114 (2014) , 11636.

~1990

Some V windows too wide to be practical Air stability can be an issue

Positive electrode materials

O3 P2

O3 higher capacity & P2 higher stability

Layered materials NaxMO2 N. Yabuuchi et al. Nature Materials 11(2012) 512

Polyanionic frameworks

Frameworks typically different from Li - based

Lower capacities than layered (« inactive groups ») Poor conductivity (C coating) High stability

2.5

3

3.5

4

4.5

0 20 40 60 80 100 120

Pote

ntia

l (V

vs N

a+ /Na)

Capacity (mAh/g)

Na3V2(PO4)2F3

A. Ponrouch et al. Energy & Environ. Sci. 6 (2013) 2361.

(a)

(b)

(c)

(d)

(e)

(f)

Negative electrode materials: hard C

Non-graphitizable (sp3 cross-linking) Prepared by pyrolisis of solid precursors (cellulose, charcoal, phenolic resins, sugar…)

graphene sheets 10 – 40 Å (1-3 layer stacks)

E. Irisarri et al. J. Electrochem. Soc. 162 (2015) A2476

Current state of the art material Very low V operation (plating risk?) 1st cycle irreversibility is an issue

capacity microstructure, electrolyte

R. Dugas et al. J. Electrochem. Soc. 2016, 163, A867.

Reported performance: lab cells

Sustainability

Hard C // EC0.45:PC0.45:DMC0.1 // Na3V2(PO4)2F3

Theoretical energy density : 78 Wh/kg (BatPac v1.0)

(for comparison Graphite//LP30//LiFePO4 gives 75 Wh/kg )

3.6 V cell 300 mAh/g (HC)

110 mAh/g (NVPF)

A.   Ponrouch, D. Monti, A. Boschin, B. Steen, P. Johansson, M.R. Palacin J. Mater. Chem. A 2015, 3, 22.

Reported performance: upscaling

Reported performance: industrial cells

http://www.faradion.co.uk Na-ion presentation http://www.faradion.co.uk/technology/354-2/

Reported performance: industrial cells

Na-ion presentation http://www.faradion.co.uk/technology/354-2/

Will performance equal / beat Li-ion?

For myself I am an optimist ,

it does not seem to be much use being anything else.

(Sir Winston Churchill, Nov. 9th, 1954 )

Ca batteries

Why Ca anode?

à “unlimited” resources 20 ppm 27640 ppm 46600 ppm Earth’s crust

à high standard reduction potential -3.04 -2.37 -2.87 vs. NHE

P. Canepa et al. Chem. Rev. 2017, 117, 4287.

Proof-of-concept Mg anode (Aurbach et al. Nature)

The Odyssey of Multivalent Cathodes

MV

M anodes: the case of Ca…

Suitable electrolytes (plating) cathode development

Reduction of the WE:

Ca stripping at the CE

Oxidation of the WE: Ca deposition ???

e-

e-

e-

e- e-

Ca2+

Ca CaxA

e-

e-

e-

V

Ca2+

Ca2+ Ca2+

Ca2+

Ca2+

e-

e-

e-

e- e-

Ca2+

Ca CaxA

e-

e-

e-

V

Ca2+

Ca2+ Ca2+

Ca2+

Ca2+

1991 Ca deposition not possible in organic solvent electrolytes Aurbach et al. (SEI does not conduct Ca2+ ions)

BUT Charge/radiusCa2+ << Mg2+

Easier migration

M anodes: the case of Ca…

Substrate

SEI

Electrolyte

Ca2+(Solvated)①

② Ca2+(Desolvated)③

Ca(Nucleationandgrowth)④

Alkyl carbonates (high Ɛ, large redox window) Commercial salts

PC EC

TFSI- ClO4- BF4

-

Ca2+ electrolytes

EC:PC RoomT

Concentration ↑ Viscosity ↑ Conductivity ↑, ↓

Low conductivities at RT Ion pairing

High T (50-100ºC)

Is Ca electrodeposition viable?

0.3 M Ca(BF4)2

0.45 M Ca(BF4)2

0.65 M Ca(BF4)2

0.8 M Ca(BF4)2

1 M Ca(BF4)2

-0.04

-0.02

0

0.02

0.04

-1 0 1 2

Inte

nsity

(mA

)

Potential (V vs Ca2+/Ca passivated

)

Ca(ClO4)2Ca(BF4)2Ca(TFSI)2

-0.008

-0.004

0

0.004

-1 0 1 2

Reversible redox process in Ca(ClO4)2 & Ca(BF4)2

Ca plating???

Is Ca electrodeposition viable?

0.3M 100°C

Intensity ↑ with: Ca(BF4)2

↑ temperature ↑ ionic conductivity

-0.04

-0.02

0

0.02

0.04

-1 0 1 2

Inte

nsity

(mA)

Potential (V vs Ca2+/Ca passivated)

Plating Stripping

0.3M -0.65 -0.52

0.45M -0.52 -0.42

0.65M -0.65 -0.51

0.8M -0.88 -0.48

Ca(BF4) EC:PC 100°C 0.3 M

0.45 M0.65 M0.8 M

Is Ca electrodeposition viable?

0.3M Ca(BF4) EC:PC

100ºC, 200h, -1.5V

Higher T, longer t

thicker deposits

higher Ca/F ratio

Bubbling in H2O: H2?

CKa

OKa

CuLaClKaClKb

CaKa

CaKb

0.50 0.90 1.30 1.70 2.10 2.50 2.90 3.30 3.70 keV

-1

-0.5

0

0.5

1

1.5

2

0 5 10 15 20 25 30 35

Op

en c

ircu

it p

ote

nti

al (

V v

s C

a2+

/Ca)

time (h)

OCV before

OCV after

Ca plating/stripping

Deposits consist of a mixture of Ca metal and CaF2 (SEI)

SEI seems stable: permeable to Ca2+ ??

Ca plating/stripping

Good cyclability BUT high polarisation

Ca//Ca

150 µA/cm2 150 cycles, 100ºC

A.   Ponrouch, C. Frontera, F. Barde, M.R. Palacin Nature Materials 15, 2016, 169

Capacity stable upon cycling

BUT: competition with electrolyte

decomposition (efficiency to be improved)

100°C

Li//Li

150 µA/cm2 150 cycles, RT

The quest for a cathode

Insertion cathodes?

e-

e-

e-

e- e-

Ca2+

Ca CaxA

e-

e-

e-

V

Ca2+

Ca2+ Ca2+

Ca2+

Ca2+

“Technology is always limited by the materials available”

DARPA, US, 1960´s

?

Is CaMn2O4 a viable cathode?

CM CFSP

Marokite (1200°C, 72h) Ca CN=8

Mn3+ / Mn4+ Th.capacity Δx=1: 250 mAh/g

CM CFSP

Spinel (not known) Ca Td ∼3V, migration barrier 0.5 eV Persson et al. 2015

What about CaMn2O4 - Marokite?

M. E. Arroyo-de Dompablo, C. Krich, J. Nava-Avendaño, M.R. Palacín, F. Bardé Chemistry of Materials 28, 2016, 6886.

0.0 0.2 0.4 0.6 0.8 1.0

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

Form

ation

Ene

rgy (

ev/f.

u.)

x in CaxMn2O4

GGA+U GGA

0.0 0.2 0.4 0.6 0.8 1.02.0

2.4

2.8

3.2

3.6

4.0

4.4

14 %

6%14%

9%

Calcu

late

d Vo

tage

(V)

x in CaxMn2O4

GGA GGA_U

(a) (b)

Ueff = 4 eV

Suitable potential BUT migration barrier > 1.5 eV

pristine

“oxidized” 100° C

OCV 100° C

Complementary characterization COMPULSORY!!!

Other alternatives?

2

2.5

3

3.5

4

0 50 100 150 200 250

Pote

ntia

l (V

vs C

a2+/C

a)

Capacity (mAh/g)

Ca-M-X

-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

1 1.5 2 2.5 3 3.5

Inte

nsity

(mA)

Potential (V vs Ca2+/Capassivated)

cycle 4 cycle 5 cycle 6 cycle 7

M-X

D. Tchitchekova et al. (in preparation)

Preliminary proof of electrochemical reactivity in some Ca-M-X and M-X phases

Other alternatives?

Complementary characterization: XRD may not be enough…

Tomographic reconstruction Transmission X-ray Microscopy

Ca L edge XANES

M-X

Ca-M-X Standards: M-X, CaCO3, CaF2

… to be continued

Ca-M-X

Towards Ca metal batteries?

e-

e-

e-

e- e-

Ca2+

Ca CaxA

e-

e-

e-

V

Ca2+

Ca2+ Ca2+

Ca2+

Ca2+

Positive Efficient Ca2+ migration Large specific capacity High operation potential

Negative Plating/stripping

Electrolyte Plating/stripping Large potential window

Operation T Efficiency

I always like to look on the optimistic side of life, but I am realistic enough to know that life is a complex matter. Walt Disney

Ackowledgements

M. E. Arroyo

C. Frontera A. Ponrouch D. Tchitchekova

F. Bardé A. Sorrentino

R. Dedryvère

P. Johansson

L. Croguennec C. Masquelier

D. Monti B. Steen

E. Irisarri