Li-stuffed garnet-type solid state electrolytes for battery applications

Li5+3xLa3Nb2-xCaxO12

Aaron KirkeyUniversity of Calgary2500 University Dr. NW, Calgary, AB, T2N 1N4Tuesday October 4, 2016

Outline1. Introduction to Li-batteries

Why batteries Why solid state Li-ion batteries Why Garnets

2. Li5+3xLa3Nb2-xCaxO12 work Why this composition? Sample preparation Synthetic results (XRD) Conductive properties (EIS) Time-dependence of conductivity (EIS) Chemical Stability + proton exchange (TGA + H2O tests) Density + microstructure (SEM + volumetric calc.) New composition Future Studies

Why batteries?1. As the use and development of renewable energy systems (wind, water, solar,

tidal, geothermal) grows, so does the world’s need to store it.

Renewables are variable, local and unpredictable yet need to meet base-load system requirements.

2. Demand for versatile, lightweight continues to grow(electric cars, portable devices).

[1] http://climatechange.lta.org/wp-content/uploads/cct/2015/04/REimage.jpg [2]https://www.tesla.com/sites/default/files/pictures/thumbs/model_s/red_models.jpg?201501121530

[1][2]

Li-ion batteries possess some of the highest gravimetric and volumetric power densities among all batteries.

[3]

[3] Tarascon, J.M.; Armand, M. “Issues and challenges facing rechargeable lithium batteries” Nature, 2001, 414, 359-367. [4] Giri, S.; Behera, S.; Jena, P. Angewandte Chemie. 2014, 126, 14136-14139. [5] http://hoverboardlab.com/wp-content/uploads/2015/12/Hoverboard-Fire-1024x535.jpg [8] Bhatt, M.D.; O’Dwyer, C. “Recent progress in theoretical and computational investigations of Li-ion battery materials and electrolytes” Phys. Chem. Chem. Phys., 2015, 17, 4799-4844.

Liquid based electrolytes are prone to excess heating, explosion and to catching fire. Most liquid electrolytes are highly toxic.[4]

[5]

Why Li-ion batteries?

~3.7V

Conventional Li-ion battery.

[8]

Why solid-state Li-garnets? Li-garnets possess reasonably good room temperature conductivity.

1 2 3 4 5 6-8

-7

-6

-5

-4

-3

-2

-1

0

Gel polymer(1M LiPF6 in EC/DMC 50:50 vol % + PVdF/HFP 10 wt %)

Garnet-type Li6.4La3Zr1.4Ta0.6O12

LISICON (Li14ZnGe4O16)

NASICON (Li1.3Ti1.7Al0.3(PO4)3) Li3N

LIPON (Li2.9PO3.3N0.46)

A-site deficient perovskite(Li0.34La0.51TiO2.94)

Liquid electrolyte(LiPF6 in EC/DC 50:50 vol %)

Thio-LISICON (Li10GeP2S12)

log10

(Scm

-1)

1000/T (K-1)

T (oC)

Structure of an ideal garnet

A3B2(XO4)3

[6]

[6] Suma’s presentation [7] http://ruby.colorado.edu/~smyth/min/images/garnet.gif [8] Thangadurai, V.; Narayanan, S.; Pinzaru, D. “Garnet-type solid-state fast Li-ion conductors for Li batteries: critical review“ Chem. Soc. Rev. 2014, 43, 4714-4727.

[7]

A

BO6

XO4

Structure of a Li5-phase garnet

Li5Nb2(LaO4)3=Li5La3Nb2O12

Li

NbO6

LaO4

[8]

Study FocusLi5La3Nb2O12 Li5-xLa3Nb2-

xCaxO12

Where x= 0, 0.05, 0.10, 0.15, 0.20, 0.25

Motivation for compounds:

• To identify periodic trends (Ba, Sr)in reactivity and electronic properties

• Synthesize a novel electrolyte

Testing and characterization:

• EIS (conductivity)• PXRD (crystal structure)• TGA (chemical & thermal

stability)• SEM (morphology & porosity)

Li5+3xLa3Nb2-xCaxO12 - Sample Preparation

• La2O3 dried for 24h at 900˚C

• Reagents weighed (10% excess Li)

• Ball milled at 200rpm for 6h

• Ball milled at 200rpm for 6h

• Heated for 6h at 700˚C

• Calcinated at 900˚C for 24h

• Ground and pressed isostatically at 180kN

• Reagents are sintered at 1100˚C or 1150˚C for 6h

XRD spectra x=0 to x=0.25

16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 800

100

200

300

400

500

600

700

16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 800

100

200

300

400

500

600

700

x=0.25

x=0.20

x=0.15

**

**

**

**

* = La2O3

1100˚C 1150˚C

x=0.10x=0.05x=0

StndrdJCPDS #80-0457

Degrees (2) Degrees (2)

Rela

tive

Coun

ts

Rela

tive

Coun

ts

Density & SEM Two temperatures were used during the final calcination step, 1100 and 1150˚C. The corresponding samples’ densities were measured. Sintering at 1150˚C produced denser pellets.

1100˚C

1150˚C

x=0.05 x=0.15 x=0.25

63%

66%

59%61%

81%82%

x=0.05, 1100˚CX=0.05, 1100˚C

Electrochemical Impedance Spectroscopy

Au current collectors were cured at 600˚C for 1 hour to either side of the sample. EIS was performed using a specialized cell.

V

Sample

Cured Au current collectors

Au leads

4000 14000 24000 34000 44000 54000 64000 74000 84000

-6E+04

-5E+04

-4E+04

-3E+04

-2E+04

-1E+04

0E+00

Z’ (Ω)

Z’’ (

Ω)

A typical impedance plot from which the resistance is obtained.

Total Resistance=R

𝜌=𝑅 𝐴ℓ

𝜎=1𝜌

and

Arrhenius Plot

RT cond. 1100˚C 1150˚CX=0

X=0.10X=0.20

1.5 2 2.5 3 3.51.00E-02

1.00E-01

1.5 2 2.5 3 3.51.00E-02

1.00E-01

1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.51.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1000/T (K) 1000/T (K)1000/T (K)

σ (S

·cm

-1)

Log

σ (S

·cm

-1)

Log

σ (S

·cm

-1)

Time-dependent EIS With time, the electrical response changed.

0.00E+00 8.00E+05 1.60E+06 2.40E+06

-1.20E+06

-8.00E+05

-4.00E+05

0.00E+00

x=0, 23˚C

0.00E+00 1.67E+05 3.33E+05 5.00E+05

-3.00E+05

-2.00E+05

-1.00E+05

0.00E+00

x=0.10, 23˚C

2.00E+04 4.50E+04 7.00E+04 9.50E+04

-1.20E+05

-8.00E+04

-4.00E+04

0.00E+00

x=0.20, 23˚C

Blue 0Orange 23h

Grey 28h

Z’ (Ω) Z’ (Ω) Z’ (Ω)

Z’’ (

Ω)

Z’’ (

Ω)

Z’’ (

Ω)

Time-dependent EIS

Orange Heating

Blue Cooling

1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6

5.00E-07

5.00E-06

5.00E-05

5.00E-04

5.00E-03

1000/T (K)

Log

σ (S

·cm

-1)

1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.61.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1000/T (K)

Log

σ (S

·cm

-1)

1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.61.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1000/T (K)

Log

σ (S

·cm

-1)

Long-term exposure (18h) to air at high temperature (300˚C) did not significantly change the conductivity.

Measurements (˚C)

RT200250300

H2O exposure tests & TGA

x=0 x=0.05 x=0.10 x=0.15 x=0.15* x=0.20 x=0.25 x=0.35*

• Distilled H2O (10mL/g). Only the parent phase Li5La3Nb2O12 was stable. Higher Ca samples were quicker to disintegrate.

After 48 hours.

0 100 200 300 400 500 600 700 800 900 10009.20E+01

9.30E+01

9.40E+01

9.50E+01

9.60E+01

9.70E+01

9.80E+01

9.90E+01

1.00E+02

1.01E+02

1.02E+02x=0.15, 1150˚C

0 200 400 600 800 100092

93

94

95

96

97

98

99

100

101

102x=0.20, 1150˚C

0 100 200 300 400 500 600 700 800 900 100092

93

94

95

96

97

98

99

100

101

102x=0.25, 1150˚C

Temperature (˚C)Temperature (˚C) Temperature (˚C)

Wei

ght %

Wei

ght %

Wei

ght %

TGA in N2 atmosphere

~5% weight loss

Truong, L.; Thangadurai, V. Chemistry of Materials. 2011, 23, 3970-3977.

New composition – Li5.55(La2.9Ca0.1)(Nb1.85Ca0.15)O12

16 24 32 40 48 56 64 72 800

20

40

60

80

100

120

140LLCNC XRD (1150˚C) vs. Standard

Degrees (˚)

Rela

tive

Coun

ts

**

* = La2O3

Future Studies•EDX for elemental mapping (La and Ca locations)•SEM for porosity measurements•EIS on all samples•CO2 stability tests•XRD on water treated samples

Thank you!