Exploring Modified Closo-Borate 

Electrolytes in All-Solid-State Batteries

By: Erin Huang

Winston Churchill High School

Mentors: Terrence Udovic, Mirjana Dimitrievska, Juscelino Leão, 

Wan Si Tang
Introduction

Goal: To synthesize non-Li-conducting salts and test their conductivity to see if 

they would be suitable solid electrolytes for all-solid-state batteries
How batteries work

Negative 

Electrode

Positive 

Electrode

Electrolyte

Cations

Discharge Charge

Negative 

Electrode

Positive 

Electrode

Cations

Electrolyte
Lithium-ion Batteries

Liquid electrolyte leaks: corrosive, flammable, explosions

Hazardous byproducts: possible HF release

Low abundance of lithium(20-70 ppm)- relatively expensive

All-Solid State Batteries

Solid Electrolyte: no leakage

No HF release

More compact

Samsung 

Galaxy Note 7

Images: news.softpedia.com, today.com
Cations

Sodium

Abundant: 23,000 ppm (sea water)

 Less expensive

 Similar properties with Lithium (alkali metals):

 +1 charge

 Small

Calcium

 36,000 ppm

 Less expensive

Moderately similar properties (alkali earth metal):

 +2 charge: will take 2 electrons. Conduct faster?

Image: ptable.com
Anions

closo-polyborate (polycarborate)- based complex hydrides

Replaced 1 B with a C

 C is more electronegative

 Changes charge distribution of 

anion cluster
Boron-Hydrogen Based Solid Electrolytes

Conductive solids

Light weight

Ordered to disordered phase change : 

Entropy causes increase in conductivity

Superionic conductivity in solids

 Cations: hop through structure

Anions: high reorientation mobility

Na2B10H10

Image: Momma, K.; Izumi, F. VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. J. Appl. 

Crystallogr. 2011, 44, 1272-1276.

T. J. Udovic, M. Matsuo, W. S. Tang, H. Wu, V. Stavila, A. V. Soloninin, 

R. V. Skoryunov, O. A. Babanova, A. V. Skripov, J.J. Rush, A. Unemoto, 

H. Takamura and S. Orimo, Adv. Mat. 26 (2014) 7622.
Na2B12H12

Na2B12H12

Image: Momma, K.; Izumi, F. VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. J. Appl. 

Crystallogr. 2011, 44, 1272-1276.

0.00E+00

1.00E-02

2.00E-02

3.00E-02

4.00E-02

5.00E-02

6.00E-02

7.00E-02

8.00E-02

9.00E-02

1.00E-01

273 323 373 423 473 523 573

Conductivity (Siemens / cm)

Temperature (K)

Conductivity of Na2B12H12

Data: T. J. Udovic, M. Matsuo, A. Unemoto, N. Verdal, V. Stavila, A. V. Skripov, 

J. J. Rush, H. Takamura and S. Orimo, Chem. Commun., 2014, 50, 3750. 
Differential Scanning Calorimetry (DSC)

DSC

Na2B12H12
Na2B12H12-xI

x

Adding Iodine to Na2B12H12 increases the conductivity at lower temperatures.

Na2B12H12–xIx

Y. Sadikin, P. Schouwink, M. Brighi, Z. Łodziana, and R. Černý, 

Inorganic Chemistry, 2017, 56 (9), 5006-5016.

Conductivity of Na2B12H12 and Na2B12H12–xIx
Adding Iodine to Na2B12H12

Iodine Solution: 4 mmol of I2 in 8 mL of CH3OH 

Sodium Salt Solution: 4 mmol of Na2B12H12 in 2 mL of water and 6 mL of CH3OH. 

1 Iodine Solution(I2 + CH3OH) : 1 Sodium Salt Solution (Na2B12H12 + CH3OH + H20)

Na2B12H12 +I2 Na2B12H12–xIx + HI

Add gradually, let evaporate/heat in oven to form solid and give off HI.

Stock 

Solutions
Na2B12H12–xI

x

Expected to see peak at 84 °C

No peak

-200 °C – 600 °C: no peak

Need to check structure
Ca(CB11H12)2

Phase 

Change?

Phase Change at 150 °C is 

closer to the temperature 

we want

Not the clearest peak

Ca(CB11H12)2

Sample
Structure of Ca(CB11H12)2

Structure of Na2B12H12-xI

x

0

20000

40000

60000

0 10 20 30 40 50 60 70

Intensity

2θ

X-ray Powder Diffraction

Amorphous

Supposed to have an 

Hexagonal Closed Pack 

Crystal Structure

NaCB11H12

Ca(CB11H12)2
Electrochemical Impedance Spectroscopy

0.00000E+00

5.00000E-04

1.00000E-03

1.50000E-03

2.00000E-03

2.50000E-03

3.00000E-03

273 323 373 423

Conductivity (S/cm)

Temperature (K)

Conductivity of Na2B12H12-xIx

Y. Sadikin, P. Schouwink, M. Brighi, Z. Łodziana, and R. Černý, 

Inorganic Chemistry, 2017, 56 (9), 5006-5016.
-8

-7

-6

-5

-4

-3

-2

-1

0

273 323 373 423 473 523 573

Log of Coonductivity Log(S/cm)

Temperature (K)

Conductivity of Na2B12H12-xIx compared to 

Na2B12H12

Conductivity Results

Na2B12H12-xIx

Na2B12H12
Conclusion

Can optimize conductivity of Na2B12H12-xIx

Look closer at our structure of Na2B12H12-xIx using neutrons

Test Conductivity of Ca(CB11H12)2

Mix Ca(CB11H12)2 with another conducting salt or infiltrate it into nanopourous 

silica
Acknowledgements

Terrence Udovic

Mirjana Dimitrievska

Juscelino Leão

Wan Si Tang

Paul Neves

Jake Gurowitz

Malgorzata Psurek

Yamali Hernandez

Julie Borchers

NIST Summer High School Intern Program

Dan Neumann

NIST Center for Neutron Research

National Institute of Standards and Technology

Center for High Resolution Neutron Scattering