Supporting Information

A scalable slurry process to 3D lithiophilic and conductive

framework for high performance lithium metal anode

Yuanming Liu,a,b 1 Xianying Qin,a,d 1 Shaoqiong Zhang,a,b Lihan Zhang,a,b

Feiyu Kang,a,b,c Guohua Chen,d,* Xiangfeng Duan,e,* Baohua Lia,c*

a Engineering Laboratory for Next Generation Power and Energy Storage

Batteries, Engineering Laboratory for Functionalized Carbon Materials,

Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.b School of Materials Science and Engineering, Tsinghua University, Beijing

100084,China.c Shenzhen Geim Graphene Center, Shenzhen 518055, China.d Department of Mechanical Engineering, The Hong Kong Polytechnic

University, Hong Kong, China.e Department of Chemistry and Biochemistry, University of California, Los

Angeles, CA 90095, USA.

1 These authors contributed equally to this work.

*Corresponding authors:

guohua.chen@polyu.edu.hk (G. Chen)

xduan@chem.ucla.edu (X. Duan)

libh@mail.sz.tsinghua.edu.cn (B. Li)

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2019

40 50 60 70 80

Inte

nsity

(a.u

.)

2 Theta (deg.)

Micro copper particle Nano copper particle

Figure S1. XRD patterns of Cu micro- and nano-particles.

(a) (b)

Figure S2. (a), (b) Front SEM images of CCP-mix current collector after slurry

coating and drying process under different magnifications.

(a) (b) (c) (d)

(e) (f) (g) (h)

(i) (j) (k) (l)

Figure S3. SEM images of top surface of various 3D porous hybrid Cu current

collectors under different magnifications: (a, b, c, d) CCP-nano; (e, f, g, h) CCP-micro;

(i, j, k, l) CCP-mix.

(a) (b)

(c) (d)

Figure S4. SEM images of CCP-mix electrodes with different ratio of micro- and

nano- copper particles: (a) 1:1; (b) 2:1; (c) 3:1; (d) 4:1.

280 284 288 292 296

O/N-C=N/OC-N/O

C-C

Binding Energy (eV)

Inte

nsity

(a.u

.)

C=C

930 940 950 960

Inte

nsity

(a.u

.)

Binding Energy (eV)

Cu 2p3/2

Cu 2p1/2

(a) (b)

392 394 396 398 400 402 404 406 408

Pyridinic-N-oxide

Graphitic NPyrrolic NIn

tens

ity (a

.u.)

Binding Energy (eV)

Pyridinic N

526 528 530 532 534 536 538Binding Energy (eV)

Inte

nsity

(a.u

.)

C-O-H

C=O(c) (d)

Figure S5. XPS spectrum of (a) Cu 2p; (b) C1s; (c) O1s and (d) N1s of CCP-mix current collector.

Table S1. Mass percent of each elements of CCP-mix current collector and each

categories of oxygen and nitrogen atoms through XPS analysis.

Element Cu C N O

Mass percent(%) 42.5 40.82 5.08 11.6

Category of

oxygen atom

Carbonyl Alkoxy

Mass percent(%) 64.52 35.48

Category of

nitrogen atom

Pyridinic N Pyrrolic N Graphitic N Pyridinic-N-

oxide

Mass percent(%) 43.88 29.28 20.78 6.06

(a) (b) (c)

(d) (e)

Figure S6. (a) STEM image of CCP-mix coating layer; (b, c, d, e) Corresponding

EDX mapping results of element Cu, C, O, N.

(a)

(b)

(c)

(d)

Figure S7. Elemental mapping results for the CCP-mix @ Li electrodes with (a) 0.5

mAh cm-2; (b) 1 mAh cm-2; (c) 2 mAh cm-2 and (d) 6 mAh cm-2 of Li deposition.

(a) (b) (c) (d)

(e) (f) (g) (h)

(i) (j) (k) (l)

Figure S8. SEM images of Li deposited on Planar Cu foil at 1 mA cm-2 with various

Li capacities: (a, b, c, d) 1 mAh cm-2, (e, f, g, h) 2 mAh cm-2, (i, j, k, l) 6 mAh cm-2.

Nuleation sites of Li

Strong connection between micro copper powder

Nano copper powder

Lithiophilic oxygen or nitrogen atom

Figure S9. Schematic diagrams of the nucleation and growth processes of Li on CCP-

mix current collector.

M:N=1:1 M:N=2:1 M:N=3:1 M:N=4:1

0 40 80 120 160 20020

40

60

80

100

120

140

Cou

lom

bic

effic

ienc

y (%

)

Cycle

1 mA cm-2, 1 mAh cm-2

Figure S10. Coulombic efficiency of CCP-mix electrodes with different mass ratio of

micro- and nano-copper particles.

0 20 40 60 80 100 120 140 160 18020406080

100120140

Planar Cu CCP-nano CCP-micro CCP-mix

Cycle

Coul

ombi

c Ef

ficie

ncy

(%)

2 mA cm-2, 2 mAh cm-2

0 20 40 60 80 10020406080

100120140

Planar Cu CCP-mix

Cou

lom

bic

Effic

ienc

y (%

)

Cycle

10 mA cm-2, 1 mAh cm-2(a) (b)

Figure S11. Coulombic efficiencies of Planar Cu, CCP-nano, CCP-micro and CCP-

mix current collector with deposition capacity and current density of: (a) 2 mAh cm-2

and 2 mA cm-2; (b) 1 mAh cm-2 and 10 mA cm-2.

Table S2. Comparison of Coulombic efficiencies of 3D hybrid Cu network current

collector (CCP-mix) to other state of art modifications.

Scaffold Current

density

(mA cm-2)

Capa

city

(mAh

cm-2)

Coulombic

Efficiency

(%)

Cycles Electrolyte Reference

2 2 99.6 300

2 6 99.4 150

N-doped

graphitic

carbon 2 8 99.1 140

1M LiTFSI

DOL/DME,

2% LiNO3

Adv. Mater.,

2018, 30,

1706216.

0.5 0.5 97.5 700

1 1 97.5 120

3 1 96 170

1 2 95 190

Crumpled

graphene

balls

1 12 96 40

1M LiTFSI

DOL/DME,

1% LiNO3

Joule, 2018,

2, 184-193

0.5 0.5 99 200

0.5 1 99 150

1 1 99 150

Double

layer

diamond

interfaces 1 2 98.4 150

1M LiTFSI

DOL/DME

Joule,2018,

2, 1595-

1609

Engineerin

g stable

interfaces

0.5 1 99 500 1M LiTFSI

DOL/DME,

5% LiNO3

Sci. Adv.

2018, 4,

eaat5168

1 1 92.2 242

4 1 93.7 240

1 5 98.3 160

LiNO3

protected

glass fiber

5 10 98.1 53

1M LiPF6

EC/DEC

PNAS,

2018, 115,

5676-5680

1 1 95 250Cu-CuO-

Ni hybrid

structure

3 0.5 95 90

1M LiTFSI

DOL/DME,

1% LiNO3

Adv. Mater.

2018, 29,

1705830

0.5 1 97 150

0.5 4 97 100

N-doped

graphene

decorated

Cu foam

1 2 97 50

1M LiTFSI

DOL/DME,

1% LiNO3

Adv. Funct.

Mater.,

2018, 27,

1606422

1 1 95.8 300

1 3 97.5 120

3 1 97.4 140

5 1 95.6 100

3D PMF

coating

10 1 94.7 50

1M LiTFSI

DOL/DME,

2% LiNO3

Adv.

Energy.

Mater.,

2018,

1703360

1 1 98.8 500

1 4 91.6 100

4 1 92 169

8 1 92.22 160

10 1 80.3 100

3 D hybrid

Cu

network

(CCP-mix)

12 1 91 70

1M LiTFSI

DOL/DME,

1% LiNO3

This work

(a)

0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.2

0.4

0.6

0.8 1st 100th 200th 300th 400th 500th 600th

1 mA cm-2, 1 mAh cm-2

Areal capacity (mAh cm-2)

Volta

ge (V

vs.

Li+

/Li)

0.0 0.2 0.4 0.6 0.8 1.0-0.10.00.10.20.30.40.50.6

4 mA cm-2, 1 mAh cm-2

Volta

ge (V

vs.

Li+

/Li)

Areal capacity (mAh cm-2)

1st 50th 100th 150th

0.0 0.2 0.4 0.6 0.8 1.0-0.2-0.10.00.10.20.30.40.50.6

8 mA cm-2, 1 mAh cm-2

Volta

ge (V

vs.

Li+

/Li)

Areal capacity (mAh cm-2)

1st 50th 100th 150th

(b)

(c) (d)

0.0 0.2 0.4 0.6 0.8 1.0-0.10.00.10.20.30.40.5

Volta

ge (V

vs.

Li+

/Li)

Areal capacity (mAh cm-2)

1st 50th 100th

1 mA cm-2, 1 mAh cm-2

Figure S12. The voltage-capacity profiles of (a) Li/planar Cu cell at 1 mA cm-2 with

Li capacity of 1 mAh cm-2 at specific cycles and (b,c,d) Li/CCP-mix cells at (b) 1 mA

cm-2, (c) 4 mA cm-2, (d) 8 mA cm-2 with Li capacity of 1 mAh cm-2 at specific cycles.

0 20 40 60 80 100 120 1400

50

100

150

200

Li foil (10 mAh cm-2) CCP-mix @ Li (4 mAh cm-2)

Dis

char

ge c

apac

ity (m

Ah

g-1 )

Cycle

0

20

40

60

80

100

120

Cou

lom

bic

effic

ienc

y (%

)

0.0

0.3

0.6

0.9

1.2

1.5

1.8

Are

al c

apac

ity (m

Ah

cm-2

)

Figure S13. Electrochemical performance of Li | LFP full cell with low N/P ratio of

2.16 (CCP-mix electrode) and 5.41 (Li foil).

0 20 40 60 80 100 120 140 160 1802.42.62.83.03.23.43.63.84.04.2

Volta

ge (V

)

Specific Capacity (mAh g-1)

0.1C-1st 1C-1st 1C-40th 1C-80th

Figure S14. Corresponding voltage-capacity profiles of full cells with CCP-mix@Li

anode and LiFePO4 cathode at 0.1 C and 1 C for specific cycles.

(a) (b)

Figure S15. SEM images of (a) planar Cu and (b) CCP-mix samples after repeated Li

plating and stripping for 100 cycles at 1 mA cm-2 with Li capacity of 1 mAh cm-2.

0 20 40 60 80 1000

20

40

60

80

100-Z

imag

e (o

hm)

Zreal (ohm)

Fresh cell 100th

0 20 40 60 80 1000

20

40

60

80

100

Fresh cell 100th

Zreal (ohm)

-Zim

age

(ohm

)

(a) (b)

Figure S16. The Nyquist curves of fresh cells and cycled cells after repeated plating

and stripping Li at 1 mA cm-2 with Li capacity of 1 mAh cm-2 for 100 cycles of (a)

Planar Cu and (b) CCP-mix samples.

S1: Explanation of the nanosized Cu particles to act as the sintering additive of Cu

microparticles.

As the literature reported1, for the melting point Tm of nanosized Cu particles:

𝑇𝑚= 𝑇0exp ( -2σ𝑀

ρ𝑚∆𝑓𝑢𝑠𝐻𝑚1𝑟

)

where T0 is the melting point of the normal bulk materials; M is the molar mass of

metal Cu; σ is the specific surface free energy; is the density; is the molar ρ𝑚 ∆𝑓𝑢𝑠𝐻𝑚

enthalpy of fusion and r is the diameter of nanosized Cu particles.

Because of the smaller diameter (r) of nanosized Cu particles, it shows the higher

specific surface free energy, thus delivers higher chemical potential than bulk

materials, inducing the lower melting point and sintering temperature of it. Moreover,

smaller the particle diameter is, the lower the melting point and sintering temperature

will be.

For the Cu based materials, Liu el al.2 has reported that the nanosized Cu

particles with average diameter of 40 to 50 nm would melt at 477 oC. When the ramp

rate is lower than 30 oC/min, the nanosized Cu particles have enough time to grow

bigger, thus show unconspicuous melting point depression. In our case, all we want to

do is just construct a stubborn skeleton to withstand the volume expansion caused by

repeated plating/stripping of Li and facilitate the ion transfer at the same time. Thus

we don’t need the fusion of Cu nanoparticles, the higher diffusion of the Cu atom

between the micro- and nano- particles is desired in achieving our goals. From the

above, 400 oC is the ideal holding temperature for the heat treatment of the CCP-mix

electrode.

Notes and references1. J. Qu, M. Hu, J. Chen and W. Han, Earth Science-Journal of China University of Geosciences, 2005, 195-198.2. W. Liu, X. Deng and Z. Zhang, Physical Testing and Chemical Analysis Part A: Physical Testing, 2004, 64-67.