148
6 Nanomaterials for Batteries
II. Radical polymers are polymers that can stably exist and graft a large number of
radical groups. This type of polymer is usually composed of two parts: the
polymer backbone that determines its processing properties and the radical
groups that determine its electrochemical performance. In general, the higher
the redox potential used as a side chain radical group, the smaller the molecular weight of the polymer main chain, and the higher the electrode density.
The structural and electrochemical characteristics of free radical polymers are
as follows:
Radical polymer doping is high but specific capacity is not high. In order to exist
a large number of single electrons on the radical polymer, it is necessary to realize
electron delocalization and extremely high spatial positions on the radical group,
for example, the active center is in a conjugated structure or a ring structure, which
is bound to increase the redox single. The molecular weight of the bulk, currently
reported electrode material, the PTVE highest specific capacity of 135 mAh/g.
The electrode reaction rate is fast. Unlike other organic reactions, due to the electronic delocalization of the electrochemically active sites of the free radical polymer,
only the outer shell electrons participate in the electrode reaction and do not involve
the cleavage and generation of chemical bonds, so the charge transfer rate is extremely
fast (10
–1 cm s
−1 ), and shows that the redox potentials of the free radical polymers
are similar (E ≈ 60 mV), the peak currents are almost equal, the reversibility is
high, and the rate performance is good.
Perfect cycle performance. The main chain of the radical polymer mainly includes
polystyrene, polymethacrylate, cross-linked polynorbornene, polyvinyl alcohol,
polyethylene oxide, and other structures. These main chain structures have a wide
electrochemical window, are structurally stable in common organic electrolytes or
aqueous systems, and do not involve the cleavage and generation of chemical bonds
during the reaction process. Therefore, free radical polymer electrode materials
generally have excellent cycle performance.
Special electrode reaction process. The electrode reaction of the free radical electrode firstly transfers the charge between the current collector and the conductive
carbon, and then the charge exchange between the free radical site connected to the
conductive carbon and the current collector, and then the charge between the free
radical site and the conductive carbon moving, the last is the movement of the charge
between the radicals on the polymer chain. In general, the main chain structure of the
polymer is not conductive, so it is necessary to add a large amount of fibrous conductive agent (VGCF) to build a conductive network to increase the electrochemical
performance of free radicals in polymer.
6 Nanomaterials for Batteries
II. Radical polymers are polymers that can stably exist and graft a large number of
radical groups. This type of polymer is usually composed of two parts: the
polymer backbone that determines its processing properties and the radical
groups that determine its electrochemical performance. In general, the higher
the redox potential used as a side chain radical group, the smaller the molecular weight of the polymer main chain, and the higher the electrode density.
The structural and electrochemical characteristics of free radical polymers are
as follows:
Radical polymer doping is high but specific capacity is not high. In order to exist
a large number of single electrons on the radical polymer, it is necessary to realize
electron delocalization and extremely high spatial positions on the radical group,
for example, the active center is in a conjugated structure or a ring structure, which
is bound to increase the redox single. The molecular weight of the bulk, currently
reported electrode material, the PTVE highest specific capacity of 135 mAh/g.
The electrode reaction rate is fast. Unlike other organic reactions, due to the electronic delocalization of the electrochemically active sites of the free radical polymer,
only the outer shell electrons participate in the electrode reaction and do not involve
the cleavage and generation of chemical bonds, so the charge transfer rate is extremely
fast (10
–1 cm s
−1 ), and shows that the redox potentials of the free radical polymers
are similar (E ≈ 60 mV), the peak currents are almost equal, the reversibility is
high, and the rate performance is good.
Perfect cycle performance. The main chain of the radical polymer mainly includes
polystyrene, polymethacrylate, cross-linked polynorbornene, polyvinyl alcohol,
polyethylene oxide, and other structures. These main chain structures have a wide
electrochemical window, are structurally stable in common organic electrolytes or
aqueous systems, and do not involve the cleavage and generation of chemical bonds
during the reaction process. Therefore, free radical polymer electrode materials
generally have excellent cycle performance.
Special electrode reaction process. The electrode reaction of the free radical electrode firstly transfers the charge between the current collector and the conductive
carbon, and then the charge exchange between the free radical site connected to the
conductive carbon and the current collector, and then the charge between the free
radical site and the conductive carbon moving, the last is the movement of the charge
between the radicals on the polymer chain. In general, the main chain structure of the
polymer is not conductive, so it is necessary to add a large amount of fibrous conductive agent (VGCF) to build a conductive network to increase the electrochemical
performance of free radicals in polymer.