10.1016/j.jpowsour.2016.01.010
Carbon-coated silicon nanotube arrays on carbon cloth as a hybrid anode for lithium-ion batteries
Silicon nanotubes were fabricated by using ZnO nanowire as a sacrificial template [18]. Typically, CC substrates (W0S1002, Phychemi Company Limited) were cut into small pieces (1-2 cm2), and then cleaned by sonication sequentially in acetone and alcohol for 10 min, respectively. The cleaned CC was then soaked in 0.0025 M zinc acetate dihydrate alcohol solution for 5 min and annealed in oven for 20 min at 300 degC to form a ZnO seed layer. A precursor 150 ml solution was prepared with 0.04 M zinc acetate dihydrate, 0.04 M hexamethylenetetramine and 0.009 M poly(ethylene imine). After preheating the precursor solution for 1 h at 95 degC, the seeded CC substrates were dipped into the solution for another 4 h and finally ZnO nanowire arrays were grown on the substrates. Subsequently, the substrates with ZnO nanowires were cleaned by deionized water and transferred into a chemical vapor deposition chamber to deposit a silicon shell. The deposition of silicon shell was achieved at 500 degC for several min with passing 4 sccm SiH4 and 20 sccm Ar at a pressure of 100 Pa. To form a carbon coating on the surface of silicon shell, another deposition process was carried out at 650 degC for 90 min with passing 4 sccm C2H2 and 20 sccm Ar at a pressure of 500 Pa. Finally, the core ZnO nanowires were selectively removed via a reduction process at 600 degC for 12 h with 20% H2 in N2 at 600 Pa, leaving a carbon-coated Si NT. For comparison, the sample of Si NT arrays/ CC was prepared without carbon deposition process.
small pieces
sonication
10 min
min
CC substrates (W0S1002
cut into small pieces
1-2 cm2
cm2
zinc acetate dihydrate alcohol solution
0.0025 M
M
cleaned CC
soaked
5 min
min
cleaned CC
annealed
20 min
min
cleaned CC
annealed
300 degC
degC
solution
prepared
150 ml
ml
solution
zinc acetate dihydrate
0.04 M
M
solution
hexamethylenetetramine
0.04 M
M
solution
poly(ethylene imine)
0.009 M
M
precursor solution
preheating
1 h
h
precursor solution
preheating
95 degC
degC
seeded CC substrates
dipped into the solution
4 h
h
silicon
several min
500 degC
degC
SiH4
passing
4 sccm
sccm
Ar
passing
20 sccm
sccm
deposition of silicon shell
pressure
100 Pa
Pa
silicon shell
deposition process
650 degC
degC
silicon shell
deposition process
90 min
min
C2H2
passing
4 sccm
sccm
Ar
passing
20 sccm
sccm
deposition process
pressure
500 Pa
Pa
N2
H2
20%
%
core ZnO nanowires
removed
600 degC
degC
core ZnO nanowires
removed
12 h
h
core ZnO nanowires
removed
600 Pa
Pa