6.3 The Theory and Research Progress of Sodium-Ion Batteries
147
There are few reports and studies on sulfate materials, in which Na 2 Fe 2 (SO 4 ) 3
has a reversible specific capacity of 100 mAh/g and an average operating voltage of
3.8 V.
6.3.1.3 Organic Compounds and Conductive Polymer Cathode
Materials.
I. The conductive polymer is a type of polymer with a large π-bond conjugated
structure, the delocalized π-bonded electrons can move freely on the polymer
chain, become insulative or semiconducting in this state, and undergo oxidative
doping (p-doping) or reducing doping (n-doping), can obtain electrical conductivity comparable to metal and is therefore called “conductive” polymer. The
first conductive polymer, polyacetylene, was discovered in collaboration with
Japanese scientist Hideki Shirakawa and American scientists MacDiarmid and
Heeger in 1977, and they received the 2000 Nobel Prize in Chemistry.
The common conductive polymers are oxyacetylene, poly-benzene, polyaniline,
polypyrrole, polythiophene, and their derivatives. They are generally prepared by
chemical polymerization and electrochemical polymerization methods, except for
polyacetylene, the polymerization products of the remaining polymers are all doped.
Its specific structure and energy storage capacity are shown in Table 6.3.
Early studies have found that the doping/demising of conductive polymers at
room temperature is accompanied by a reversible redox process. This phenomenon
has attracted interest in secondary batteries. Subsequent studies show that conductive
polymers have a certain energy storage capacity in both organic and aqueous systems,
and their capacity is determined by the degree of doping. According to the data in
Table 6.3, the doping of other polymers except polyaniline is not higher than 40%,
and the corresponding theoretical specific capacity is not higher than 150 mAh/g,
while polyaniline with high doping degree is fully charged. The state is unstable.
Table 6.3 The structure and properties of several common conductive polymers
Polymer name
Structure
Maximum doping Theoretical specific
capacity(mAh g −1 )
Potential
(V vs. Na + /Na)
Oxyacetylene(PAc)
0.07
144
0–2.0(n)
3.5–4.0(p)
Poly-benzene(PPP)
0.4
141
0–1.0(n)
4.0–4.5(p)
Polyaniline(PAn)
1.0
295
2.5–4.0
Polypyrrole(PPy)
0.33
136
2.5–4.0
Polythiophene(PTh)
0.25
82
0–2.0(n)
3.0–4.2(p)
147
There are few reports and studies on sulfate materials, in which Na 2 Fe 2 (SO 4 ) 3
has a reversible specific capacity of 100 mAh/g and an average operating voltage of
3.8 V.
6.3.1.3 Organic Compounds and Conductive Polymer Cathode
Materials.
I. The conductive polymer is a type of polymer with a large π-bond conjugated
structure, the delocalized π-bonded electrons can move freely on the polymer
chain, become insulative or semiconducting in this state, and undergo oxidative
doping (p-doping) or reducing doping (n-doping), can obtain electrical conductivity comparable to metal and is therefore called “conductive” polymer. The
first conductive polymer, polyacetylene, was discovered in collaboration with
Japanese scientist Hideki Shirakawa and American scientists MacDiarmid and
Heeger in 1977, and they received the 2000 Nobel Prize in Chemistry.
The common conductive polymers are oxyacetylene, poly-benzene, polyaniline,
polypyrrole, polythiophene, and their derivatives. They are generally prepared by
chemical polymerization and electrochemical polymerization methods, except for
polyacetylene, the polymerization products of the remaining polymers are all doped.
Its specific structure and energy storage capacity are shown in Table 6.3.
Early studies have found that the doping/demising of conductive polymers at
room temperature is accompanied by a reversible redox process. This phenomenon
has attracted interest in secondary batteries. Subsequent studies show that conductive
polymers have a certain energy storage capacity in both organic and aqueous systems,
and their capacity is determined by the degree of doping. According to the data in
Table 6.3, the doping of other polymers except polyaniline is not higher than 40%,
and the corresponding theoretical specific capacity is not higher than 150 mAh/g,
while polyaniline with high doping degree is fully charged. The state is unstable.
Table 6.3 The structure and properties of several common conductive polymers
Polymer name
Structure
Maximum doping Theoretical specific
capacity(mAh g −1 )
Potential
(V vs. Na + /Na)
Oxyacetylene(PAc)
0.07
144
0–2.0(n)
3.5–4.0(p)
Poly-benzene(PPP)
0.4
141
0–1.0(n)
4.0–4.5(p)
Polyaniline(PAn)
1.0
295
2.5–4.0
Polypyrrole(PPy)
0.33
136
2.5–4.0
Polythiophene(PTh)
0.25
82
0–2.0(n)
3.0–4.2(p)