Oxide-Coated Titanium Dioxide Nanotubes in Sodium-Ion Batteries
Andreas Savva, Kassiopeia Smith, Steven Letourneau, Elton
*
Graugnard ,
Hui Xiong˟
Department of Materials Science & Engineering, Boise State University, Boise, ID 83725 USA
*email: eltongraugnard@boisestate.edu
˟email: clairexiong@boisestate.edu
4. ATOMIC LAYER DEPOSITION
Hypothesis: Coating the titania (TiO2) nanotube anode
with alumina (Al2O3) and TiO2 will stabilize the solid
electrolyte interphase (SEI) layer and subsequently
increase the reversible capacity of the sodium ion
battery.
Separator
Ion
C
a
t
h
o
d
e
A
n
o
d
e
•  Self-limiting surface reactions
•  Deposits a conformal thin film
with precise levels of thickness
•  Used to deposit Al2O3 and
TiO2 on TiO2 nanotube anodes
•  Coatings of 2, 4, and 8 nm of
Al2O3 were deposited at
120°C
FIGURE 7: Diagram of atomic layer deposition
(ALD) process depicting the surface being
purged and coated with precursors2
FIGURE 1: A battery that is
discharging its energy to power
a light source
2. SOLID ELECTROLYTE INTERPHASE
Discharge Capacity vs. Cycle for
Bare TiO2 Anode
SEI Layer
Cons: Large capacity loss, low
irreversible capacity
Discharge Capacity vs. Cycle for
Coated TiO2 Anode
SEI Layer
TiO2
nanotubes
FIGURE 3:
Pros: Lower capacity loss
Coulombic Efficiency
5. CONSTRUCTION & TESTING
•
•
•
•
•
Stainless steel current collectors
Sodium metal cathode
Glassy fiber separator
1 M EC: PC electrolyte
Oxide-coated TiO2 nanotube
anode
•  Batteries tested at 10 µA
•  Tested for 10 cycles
FIGURE 8: Diagram of coin cell
construction
Al2O3 Coating
3. ANODIZATION
Ti foil
FIGURE 4: General
process of anodization
7. SUMMARY
TiO2 nanotubes
Anodization
Tube diameters: 40-60 nm
FIGURE 5:
Anodization setup with titanium
foil as anode
(red) and
platinum mesh as
counter electrode
(black)
FIGURE 6: Image
taken via
scanning electron
microscope of
TiO2 nanotubes
after anodization
Summary:
•  TiO2 nanotubes were coated in Al2O3 and TiO2 and used as anodes in
sodium-ion batteries
•  2 nm Al2O3 coating on amorphous TiO2 increased capacity and coulombic
efficiency, while 4 and 8 nm Al2O3 coatings drastically decreased capacity
•  Al2O3 coatings had little effect on anatase TiO2 batteries
•  TiO2 coatings slightly improved anatase TiO2 coulombic efficiency
•  Significant variation was observed in control samples
Future Work:
•  Investigate 2 nm Al2O3 coatings on amorphous TiO2 nanotubes to confirm its
positive effect
•  Improve process control to minimize variations in sample preparation
Acknowledgments
References
This project was supported by NSF grant no. 1359344 and the Materials REU program at Boise State University.
We also thank the students and staff of the Department of Materials Science & Engineering.
2.
1.
TiO2-coated
amorphous TiO2
Cons: Lower initial capacity
TiO2-coated
anatase TiO2
TiO2
nanotubes
FIGURE 2:
Pros: High initial capacity
Specific Capacity
Al2O3-coated
anatase TiO2
Electrolyte
Lithium-ion batteries are a common type of renewable
energy storage. Concerns about their cost and material
availability have led to sodium-ion batteries (NIBs)
being considered as a viable alternative1. In order to
compete with lithium-ion technology, the storage
capacity and stability of NIBs must be improved.
6. RESULTS
Al2O3-coated
amorphous TiO2
1. INTRODUCTION
Kim, S. W., Seo, D. H., Ma, X., Ceder, G., & Kang, K. (2012). Electrode materials for rechargeable sodium-ion batteries: Potential alternatives to current lithium-ion batteries. Advanced Energy Materials, 2(7), 710–
721. http://doi.org/10.1002/aenm.201200026
"Atomic Layer Deposition." — Institut Für Mikrosystemtechnik – IMTEK. Universitat Freiburg, n.d. Web. 15 June 2015.