第二章 文獻回顧
2.4 電紡絲法
電紡絲法是一個很容易將材料尺寸縮小到奈米等級的方法，在經 過修飾改良可以得到一個具有高表面積的材料。
圖.2-15 電紡絲示意圖
電紡絲法是利用直流高壓電使高分子溶液或熔體帶有電荷，當 高分子溶液藉由注射式針筒由針管末端流出時，會因為高電荷將高分 子溶液噴射出來，噴射後會形成奈米尺寸的纖維，並在接地端得收集 器上聚集。
當高分子溶液到達針管末端時，會因為液體表面張力形成液滴狀，
此時高壓的電場會使液體表面充滿電荷，相同電荷產生排斥力相反於 表面張力，當隨著電場強度逐漸增強，針管末端的液滴會因電荷影響 向前延伸，而形成圓錐狀，此稱為泰勒圓錐(Taylor Cone)。再增加電
26
Fibers Set-up Morphology Advantages Disadvantages
Randomly
oriented
A plate collector
Simple Non-uniform film
thickness
Drum collector, rotating at a
low speed
Uniform thickness A motor is required
to keep the collector
rotating
Aligned
Drum collector, rotating at a
high speed
Long aligned fibers are
possible
High rotating speed;
difficult to obtain
thick films
Disk collector, rotating at a high
speed
Long aligned fibers are
possible
Small area and
difficult to obtain
thick films
27
Wire drum collector, rotating at
a low speed
Do not need a high
rotating speed
Difficult to obtain
thick films
Two parallel plate collector
Simple approach Length of fiber is
restricted by the gap
distance; difficult to
obtain thick films
Core/shell
structure
Dual nozzle spinning with two
different polymer solution
Core–shell structured
fiber
Outer and inner
solutions may diffuse and mix
together
Coaxial spinning with mineral
oil inside and polymer solution
outside
Diffusion of inside
solution can be
avoided
Require additional
process to remove oil
由文獻得知目前電紡絲法可以做為二次電池材料的構型分別如 下圖.2-16，通過纏繞靜電紡絲和熱處理，具有可控相位 1D 奈米纖維
（例如聚合物，金屬和陶瓷）
，形態（例如多孔的，空心的，並且核-殼）和組合物（例如，金屬/金屬氧化物，碳/金屬或金屬氧化物的複 合材料）可以容易地獲得。這意味著，與（i）大的表面積和高的比
28
Precursors Chemical structure Electrospinning condition
Functionalities Advantages Disadvantages
PAN 4–10 wt.% in DMF, 10–30
kV
Carbon source for
CNFs and their
hybrids
Carbon source for
CNFs
High carbon
yield (60% at
1000oC)
Low spinnability
29
Lignin
-
20–35 wt.% in DMF/water,6–26 kV
Carbon source for
CNFs
Large surface
area
Large diameter; low
carbon yield of
20–40%
PI
PMDA/ODA type
10–20 wt.% in N-methyl,
pyrrolidone/THF/methanol/
DMAc, 8–25 kV
Carbon source for
CNFs, separator for
LIB
acetone, 15–20 kV
Separator and gel
electrolyte for LIB
High mechanical
ethanol/DMF, 10–25 kV
Carbon source for
metal oxide/CNF
composites and
template for neat
metal oxide fibers
Soluble in
various solvent
Low carbon yield of
~15%
PVA 10 wt.% in water, 8–35 kV Carbon source for
metal oxide/CNF
composites
Water soluble Low carbon yield of
3–10%
PS 8–10 wt.% in DMF, 10–
20 kV
Scaffold for neat
metal oxide fibers
and sacrificial
phase for voids
Compatible with
other host
polymer, such as
PAN
Difficult to be fully
removed, requiring
1000oC
PMMA 5–35 wt.% in DMF/THF/
chloroform, 15–25 kV
Scaffold for neat
metal oxide fibers
and sacrificial
phase for voids
Easy to be
decomposed at
~450oC
Poor compatibility
with host polymer,
beads are easy to
30
圖.2-17 碳纖維修飾孔洞(a)多孔碳纖維(b)介孔通道與微孔的碳纖維(c) 有序的介孔碳纖維(d)層次結構碳纖維
84
經過以上整理鋰氧電池的碳基材，需要高孔洞囤積放電產物與氮 摻雜的碳基材有助於 ORR 作為結合，電紡絲法中的膠體溶液前驅物 高分子聚丙烯腈(PAN)在經過兩階段煅燒時會有環化反應
85
，形成氮 摻雜的石墨如圖.2-18 和圖.2-19；利用兩種高分子熔點不同使纖維在 經過煅燒後，低熔點的高分子熔化使纖維產生孔洞形成 a 型的多孔纖 維，最高比表面積可到 940 m2
/g86
。31
圖.2-18 煅燒過程中 LiFePO
4
與 PAN 反應機制圖(A)兩階段煅燒示意圖 (B)預煅燒過程中 PAN 環化(C)高溫煅燒後 PAN 石墨化85
圖.2-19 PAN 石墨化反應機制
87-88
32
由文獻得到，使用XPS分析PAN經過環化再石墨化結構如圖.2-20，
氮摻雜的形式有pyridinic (B.E.= ~398.5 eV)、quaternary (B.E.= ~401.1 eV)和nitrogen oxides (B.E.= ~402.2 eV)三種
89
。圖.2-20 PAN 石墨化後 XPS 分析材料結構
89
33
MW=1.5×10
4
AldrichPoly(methyl methacrylate) (PMMA)
(C
5
O2
H8
)x
MW=1.2×10
5
AldrichN,N-Dimethylformamide (DMF)
C
3
H7
NOanhydrous：99.8% w/w Aldrich
Iron(II) phthalocyanine (FePc)
C
32
H16
FeN8
>95.0% Aldrich
Sodium nitrite NaNO
2
>98.5% TCI
4-Aminopyridine (4-AP)
C
5
H6
N2
>99.0% TCI