Supplementary
Information
Selective formation of predominantly pyridinic type nitrogen-doped graphene
and its application in lithium-ion battery anodes
Jacob D. Bagley,
a
Deepan
Kishore Kumar,
b
Kimberly See,
a
Nai-Chang
Yeh*
c
a
Division of
Chemistry
and Chemical Engineering,
California Institute
of Technology, Pasadena,
CA, 91125, USA
b
Department
of Electrical Engineering, California
Institute
of Technology,
Pasadena, CA,
91125, USA
c
Department of Physics, California Institute
of Technology, Pasadena, CA,
91125, USA
* Corresponding author.
Tel: +1 (626)
395-4313. E-mail: ncyeh@caltech.edu (Nai-Chang Yeh)
Supplementary Note 1
Supplementary Note 2
Supplementary Note 3
Supplementary Note 4
Supplementary Figure 1
Supplementary Figure 2
Supplementary Figure 3
Supplementary Figure 4
Supplementary Figure 5
Electronic
Supplementary
Material
(ESI)
for
RSC
Advances.
This
journal
is
©
The
Royal
Society
of
Chemistry
2020
Supplementary Note 1: Experimental setup
for high-yield
graphene synthesis
In
order
to fabricate
large
amounts
of
GNSPs
efficiently,
we
built
a PECVD
deposition
system
with
eight
chambers
in parallel
shown
in
Fig.
S1.
Input
of
hydrogen
and
methane
gas
is controlled
by
mass
flow
controllers
(MFCs),
and
input
of
3-chloropyridine
is controlled
by
a leak
valve
which
is
connected
to
a vacuum
sealed
vial.
The
pressure
is measured
by
a pressure
gauge
(PG),
and
the
gas
composition
is measured
by
a residual
gas
analyser
(RGA).
The
gases
are
split
to eight
quartz
chambers
which
each
have
Evenson
cavities
connected
to
microwave
power
sources.
A cold
trap
(CT)
captures
harmful
by
products
of the
reaction
(HCl,
etc),
and
a vacuum
pump
(VP)
is
continually
pumping
the
system.
The
pressure
is controlled
by
a throttle
valve
(TV)
that
opens
and
closes
with
feedback
from
the
pressure
gauge
to
maintain
a pressure
setpoint.
We
have
also
measured
the
pressure
in
the
quartz
chamber,
and
under
the
conditions
of
this
experiment
(
i.e.
,
a
pressure
of
4.8
Torr
at
PG
and
hydrogen
and
methane
flow
rates
of
48
sccm
and
5 sccm,
respectively)
the
pressure
in
the
chamber
is
~500
mTorr,
consistent
with
the
previous
report
of
Hsu
et
al
[14].
Fig. S1.
Schematic of the eight-chamber
PECVD
graphene growth system.
Supplementary Note 2: Determining the yield of N-GNSPs per
chamber
The
yield
of
N-GNSPs
synthesized
on
copper
substrates
as
a function
of
time
is shown
in Fig.
S2
for
one
PECVD
chamber.
A
fit
of
these
data
reveal
a growth
rate
of
~ 6 mg/cm
2
/hr.
Our
deposition
chamber
affords
~ 1 cm
2
substrates
within
each
plasma
cavity,
so
our
eight
chamber
growth yields
a growth rate of ~
48 mg/hr of N-GNSPs.
Fig. S2.
Yield of N-GNSPs-
vs.
-time obtained from one PECVD growth chamber.
Supplementary
Note
3: Procedure
for
fabricating
coin
cells
of lithium
ion
batteries (LIBs)
The
procedure
for
fabricating
two
types
of
LIB
coin
cells
with
N-GNSPs
as
the
anode
is
schematically shown below
in Fig. S3.
Fig. S3.
Schematic of typical coin cell fabrication
(left) and fabrication of coin cell using N-
GNSP not removed from
the growth substrate
Supplementary
Note
4:
Procedure
for
estimating
GNSPs
and
N-GNSPs
capacitance
According
to
the
widely
accepted
Electrochemical
Methods
by
Bard
and
Faulkner,
1
double
layer
capacitance
can
be
estimated
from
the
slope
of the
voltage
vs
.
time
response
due
to
a current
step.
To
appropriately
perform
this
measurement,
however,
the
electrochemical
response
must
be
due
to
non-faradaic
(capacitive)
processes
rather
than
faradaic
(redox)
processes,
which
can
be
ensured
by
measuring
the
voltage
vs
time
response
shortly
after
the
current
step,
as
non-faradaic
processes
tend
to
be much
faster
than
faradaic
processes.
Therefore,
we
used
the
first
ten
seconds
of
the
first
galvanostatic
discharge
of
GNSPs
and
N-GNSPs
to
estimate
their
capacitances
(shown
in
Fig.
S4).
The
fairly
linear
slopes
indicate
that
the
electrochemical
response
during
this
time
is,
in
fact,
dominated
by
non-faradaic
processes,
as
faradaic
processes
tend
to cause
voltage
plateaus
in galvanostatic measurements. The capacitance is calculated according to
퐶푎푝푎푐푡푖푎푛푐푒
=
퐶푢푟푟푒푛푡
푆푙표푝푒
The
respective
slopes
of the
GNSPs
and
N-GNSPs
discharge
curves
are
-0.0093
V/s
and
-0.018
V/s, corresponding to capacitances of 5.6 F/g and 10.8 F/g.
Fig. S4.
First ten seconds of GNSPs and N-GNSPs first galvanostatic discharge curve.
Reference:
1.
Electrochemical
Methods:
Fundamentals
and
Applications
,
A.
J. Bard
and
L.
R.
Faulkner,
ISBN: 0471055425,
John Wiley & Sons, Inc. (1980).
Fig.
S5.
Raw
data
(before
smoothing)
of
Fig.
5, showing
that
the
same
peaks
and
shifts
are
still
visible and apparent,
which validates
the data treatment used to generate Fig. 5.