(00
2)
(00
3) (hk0)
electrical contact
top electrode
electrical
contact
plastic body
bottom
electrode
window
gasket cell
stack
window
Operando PXD of Vanadium-Based Nanomaterials as
Cathodes for Mg-ion Batteries Christian Kolle Christensen,a
Daniel Risskov Sørensen,a Espen Drath Bøjesen,b Jette Mathiesen,b,c
Jonas Hyldahl
Kristensen,a Bo Brummersted Iversen,b and Dorthe Bomholdt
Ravnsbæka aDepartnemt of Physics, Chemistry, and Pharmacy,
University of Southern Denmark, bDepartment of Chemistry, Aarhus
University, cDTU Energy, Danish Technical University
0,00 0,05 0,10 0,15 0,20 0,25 0,30 0,35 0,40
0,00 0,05 0,10 0,15 0,20 0,25 0,30 0,35 0,40
5
x in MgxV
2O
5-nanotubes
2th
eta
(degre
ss)
0,600,650,700,750,800,850,900,951,00
0,600,650,700,750,800,850,900,951,00
2
4
6
x in Mgx
V2
O5
-nanotubes
2theta (degress)
0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00
0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00
2
4
6
x in MgxV
2O
5-nanotubes
2th
eta
(de
gre
ss)
0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00
0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00
2
4
6
x in MgxV
2O
5-nanotubes
2th
eta
(de
gre
ss)
0.0 0.2 0.4 0.6 0.8 1.0
24
25
26
27
28
29
30
x in MgxV
7O
16-nanotubes
Inte
rlayer
spacin
g (
Å)
0
10
20
30
40
50
60
70
80
90
100
"Forming"
"Forming"
(100)
No
rmaliz
ed
peak in
ten
sity
(100)
During discharge of the battery the (001) diffraction signal
moved to lower angles, corresponding to
a larger interlayer spacing, and decreased in intensity.
Simultaneously a new peak formed at a higher
angles corresponding to shorter interlayer spacing.
Mg-intercalation in the multiwalled VOx-NTs occurs within the
space between the individual
vanadium oxide layers building the walls of the nanotubes while
the underlying VOx-frameworks
constructing the walls are affected only to a minor degree by
the intercalation.
Conclusions
• Mg2+ was successfully intercalated into VOx-NTs
• Expansion and subsequent distortion of V7O16-layers
- Increase in interlayer spacing
- Second and smaller interlayer spacing forms
• Results indicate 150 mAh/g reversible capacity at
C/10-rate
Fig 4: TEM micrograph of as
prepared C12-VOx-NTs
Fig 7: A) Operando PXD patterns as function cell discharge
state, B) Principal
(001) layer spacing for selected discharge states, showing a new
forming interlayer,
C) interlayer spacing and normalized intensities as function of
discharge state.
Acknowledgements
We thank the Villum Foundation under the Young
Investigator Program for funding. DanScatt are kindly
acknowledged for financial support. We also thank the
beamline staff at I711 for their kind assistance and
Max-lab for providing beamtime.
Contact information
E-mail: [email protected]
Phone: 61 71 21 84
Fig 5: PXD pattern of as prepared
C12-VOx-NTs obtained with a
CuKα source
Fig 3: Schematic illustration of the multiwalled VOx-NT
structure. Five fold (square pyrimidal)
coordinated V are depicted in blue and four fold (tetrahedral)
coordinated V are depicted in green.
The protonated primary amines, acting as spacer molecules are
entered in red. Adapted from ref. 5.
Fig 2: Schematic drawing of the AMPIX
battery cell for operando PXD
measurements battery electrode
materials. Adapted from ref. 4.
2.7
7nm
~50nm
a
c
a
b
Mg(s
) →
Mg
2+ +
2e-
VV +
e- →
VIV
Mg2+
e- V
A
References
1. Van Noorden, R. The rechargeable revolution: A better
battery. Nature 507, 26–28
(2014).
2. Pellion Technologies, “Moving Beyond Lithium with Low-Cost,
High-Energy,
Rechargeable Magnesium Batteries”, Pellion White Paper,
September 2011
3. Saha, P. et al. Rechargeable magnesium battery: Current
status and key
challenges for the future. Prog. Mater. Sci. 66, 1–86
(2014).
4. Borkiewicz, O. J. et al. The AMPIX electrochemical cell: a
versatile apparatus for
in situ X-ray scattering and spectroscopic measurements. J.
Appl. Crystallogr. 45,
1261–1269 (2012)
5. McNulty, D. et al. Synthesis and electrochemical properties
of vanadium oxide
materials and structures as Li-ion battery positive electrodes.
J. Power Sources
267, 831–873 (2014).
Exchanging the active specie, Li+ in Li-ion batteries by Mg2+
(Fig 1), are projected to boost the
energy density and lower the cost per kilo-watt-hour
significantly, making the Mg-ion battery
technology a promising candidate for one of the battery
technologies of the future.1,2 Batteries
based on Mg-ions has some inherited advantages over the well
known Li-ion types; higher
volumetric capacity (Wh/L), higher gravimetric capacity (Wh/kg),
lower cost and feasibility of
Mg metal as anode and hence possibly safer chemistries. But
there are still challenges due to the
higher charge density of the active ion resulting in e.g.
sluggish kinetics. Development of novel
electrode materials for effective Mg-ion storage is a vital step
for the realization of this battery
technology.3
We have synthesized series of vanadium oxides with varying
chemical composition and varying
nanotopologies, e.g. multiwalled vanadium oxide nanotubes
(VOx-NTs). The mechanism for
Mg-intercalation and deintercalation was studied by operando
synchrotron powder X-ray
diffraction measured during battery operation using the AMPIX
battery cell (Fig 2).4
• The VOx-NTs were synthesized via a
hydrothermal route
V2O5 + 2C12H25NH2 160℃, 7 days
VOx-NTs
• The resultant VOx-NTs consists of
multiwalled scrolls of crystalline VOx
layers with approximate composition
V7O16 and primary amines in between
the layers acting as spacer molecules.
• The structure allows for reversible
intercalation and deintercalation of
guest ions.
• TEM micrographs (Fig 4) of the VOx-
NTs as prepared was collected on a FEI
"Talos" F200X (S)TEM-microscope
verifying the multiwalled tube
structure.
• In house PXD diffraction (Fig 5) of the
VOx-NTs as prepared was obtained on
a Rigaku Miniflex difractometer.
• 00l reflections are found at low angles.
These are assosiated with the interlayer
spacing, c = 27.7Å.
• hk0 reflections are found at higher
angles. These can be fitteded to the 2D
tetragonal basal layer (Fig 3) with
• a = b =6.12Å.
• The obtained black VOx-NT powder
was mixed with conductive carbon
black and a binder material in the ratio
• 60 : 20 : 20 wt%
• active material : carbon : binder
• and uniaxial pressed (1.8T) to a pellet.
• Mg metal, with a ~1mm Ø hole to
allow passage of the X-ray beam, was
used as anode material
• 1M Mg(ClO4)2 in acetonitrile was
used as electrolyte and whatmann
filter as separator.
• Measured at I711 beamline at MAX-
lab using 0.9940 Å wavelength.
• Discharge curve is shown in Fig 6.
Fig 1: Schematic illustration of the
working principal of a secondary
Mg-ion battery with Mg metal (grey)
as anode and a vanadium compound
(blue) as cathode.
ano
de
cath
od
e
sep
arat
or
electrolyte
A
C
Fig 6: Discharge potential at C/10-rate as a function of Mg
inserted into
the host VOx-NT material. Discharge time equal to 10h.
0,0 0,2 0,4 0,6 0,8 1,00,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
MgxV
7O
16-nanotubes
C/10-rate
1M Mg(ClO4)2 in acetonitril
Pote
ntia
l (V
)
x in MgxV
7O
16-nanotubes
10 15 20 25 30 35
Inte
nsity (
a.u
.)
2theta (degrees)
x = 0.00
x = 0.25
x = 0.50
x = 0.75
x = 1.00
B
(00
1)
”Fo
rmin
g”
d-spacing (Å)
(001)
(001)
bea
m d
ow
n
x in MgxV7O16-nanotubes
