New 3D-structured graphene as battery electrodes D structured... · 2020. 9. 25. · Porous...
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Light 3D porous structures Rosa Chierchia / Theodoros Dikonimos /Neda Bahremandi Tolue/Caterina Lofaro/ Giuliana Faggio/Nicola Lisi/ Pierpaolo Prosini TERIN/PSU/ ABI 3D-structured graphene for battery electrodes Luogo e data
Transcript of New 3D-structured graphene as battery electrodes D structured... · 2020. 9. 25. · Porous...
Light 3D porous structures
Rosa Chierchia / Theodoros Dikonimos /Neda Bahremandi Tolue/Caterina Lofaro/ Giuliana Faggio/Nicola Lisi/ Pierpaolo Prosini
TERIN/PSU/ ABI
3D-structured graphene for battery
electrodes
Luogo e data
Why porous electrodes?
Reducing Li diffusion time in Li-Batterys (LiBs)
• Energy density and long term retention is becoming indispensable for modern ultrathin flexible, portable electronic, transportation and electrical energy storage
• As Lithium ions diffusion time through an electrode material is τeq ∼ L 2 /D
where D diffusion coefficient and
L diffusion length reducing L will improve LiBs performances
• A particularly effective way of achieving critical dimensions on micro/nanometer length scales is to employ porous electrodes
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Anode
(graphite)
Cathode
LiMxOy
Ele
ctr
oly
te
- +
Li+
Cu Al
e-
Why porous electrodes?
Further motivations
• Good access of the electrolyte to the electrode surface.
• Surface area in a porous material is large, facilitating charge transfer
across the electrode/electrolyte interface.
• The walls of active material surrounding the pores can be very thin
reducing path lengths for ion diffusion.
• The small feature sizes permit increased utilization of active material, so
that specific capacities can be increased, particularly at high charge/
discharge rates.
• Porous composites can incorporate a secondary conductive phase to
improve conductivity and high rate capacities of active phases with low
intrinsic conductivity or low mechanical strength
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Porous electrodes
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Li-ion
Li-S
pseudocapacitorsARLBs
EDL-capacitors
LiO2
TiO2
Fe2O3
O2
Co3O4
SnO2
Mo2S2
LiMn2O4 V2O5
GeO3 Li2CoO2
Conductive polimers Li4T5O12
LiF3PO4
Porous electrodes
• Here is a list of porous electrodes
unfeasible in their bulk form
because of their large volume
change or low intrinsic
conductivity
Why Graphene or Carbon nanowalls (CNWs)
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• On the anode side carbon is the most prominent electrode material due to its low cost and high
capacities
• Carbon is ecologically friendly and sustainable
• Graphene is a thin layer of pure carbon. It is the thinnest compound known to man at one atom
thick, as well as the best known conductor
• Graphene is already suggested as a replacement for activated carbon in supercapacitors, due to its
high relative surface area and a higher surface area means a better electrostatic charge storage
In this talk the deposition techniques for Graphene and CNWs as porous electrode for Li based
electrochemical accumulators will be described:
The 3D structure originates from Ni foam scaffold
Graphene is deposited by CVD on Ni open-pore wire-foam
CNWs are deposited by Hot filament plasma enhanced CVD on Ni open-pore wire-foam
In both cases the metallic scaffold will be etched by using FeCl3 and HCl
In order to improve the functionality of the resulting elctrodes are dipped in Si nanopaticles or
polymer (policaprolattone (PCL))
The material will be characterized by SEM measurement, Raman and XRD
Outline:
Instrumentation and growth techniques are similar: Very High
growth temperatures are needed for optimal crystalline
material in Chemical Vapour Deposition (CVD)
Schiume di grafene o
Graphene foams grown on a
Ni foam sacrificial templates:
Catalytic decomposition of
methane at 1000°C. Very
light and conductive ,
interesting for batteries.
Carbon Nanowalls grown on
Ni foam sacrificial template
(plasma CVD) at 600°C
Growth technique for graphene
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CVD system for graphene growth :
• In typical CVD, the substrate is exposed, at very
temperature (1000-1100°C), to one or
more volatile precursors
which react and/or decompose on the substrate surface
to produce the desired deposition
Graphene Characterisation
SEM picture of Ni foam
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SEM picture of free standing graphene
SEM images of graphene foams
• SEM picture of a 3D structured graphene grown
at 1080°C at low a) and intermediate
magnification b) The different intensity
corresponds to different thickness of graphene
and nichel cristallite
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a) b)
20 30 40 50 60 70 80 90
Inte
nsity (
a. u
.)
2 Theta (°)
IGNi81_Si
Graphene elctrodes are dipped in Si nanopaticles or polymer
XRD curves of 3D-Gr with Si NPs on the top
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Si NPs
XRD of 3D-Gr with PCL on the top
20 40 60 80
0
500
1000
1500
2000
2500
Inte
nsità
2theta
149_1080_pcl_CD
PC
L
PC
L
CVD Plasma enhanced deposition of CNWs foams
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Hot filament plasma enhanced CVD: high
power plasma, thick CNW deposit (10s of mm)
In this technique the CVD technique is helped
by plasma to growth structured graphene
Deposition of CNW occurs through
the full foam thickness (1-2mm)
Free standing CNWs by Hot filament plasma
enhanced CVD
SEM micrograph of carbon nanowalls
CNW grow through all the foam
thickness
TEM edge on view, the ultrathin wall
structure is clearly visible
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Carbon Nanowalls grown on
Ni foam sacrificial template
(plasma CVD) at >600°C
20 40 60 80
0
200
400
600
800
1000
1200
Inte
nsità
(°)
2Theta (°)
NiCNW_Si
Free standing CNWs by Hot filament plasma enhanced
CVD with Si nanoparticles (NPs) on the top
XRD curves of 3D-CNWs
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Free standing CNWs with Si nanopaticles
on the top
Si NPs
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Conclusions
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Porous electrode for LiBS have proved better
performances
3D Graphene and 3D-CNWs Plasma CVD
have been grown and studied
3D-Graphene as anode for LiBs: Larger contact
area, lower diffusion length for Li+, possibility to
store conductive elements (reducing volume
change) and lightness
The functionality of the electrodes can be
improved by dipping them in Si nanoparticles
or polymers
Possibility to use as a conductive/active
scaffold to coat with other active materials
Work in progress, electro-chemical tests
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Thank you for your attention
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Autore
e contatti:
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Rosa Chierchia / Theodoros Dikonimos /Neda Bahremandi Tolue/Caterina Lofaro/
Giuliana Faggio/Nicola Lisi/ Pierfrancesco Atanasio/Pierpaolo Prosini
ENEA TERIN/PSU/ ABI
