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Boosting lithium storage in covalent organic framework via activation of 14-electron redox chemistry

by:HGB     2019-11-30
Co-conjugated polymer molecules are considered as promising electrode materials for the next generation.
Power generation-
Storage technology due to its chemical flexibility, environmental benefits and cost advantages at the molecular level.
However, low capacity, poor structural stability, and slow ion/electron diffusion dynamics remain obstacles that must be overcome before any actual implementation.
Here we report the synthesis of afew. layered two-
The size of the carbon nanotubes captured as lithium negative electrodes of the bonded organic skeleton-ion batteries.
It is worth noting that when activated, this organic electrode provides a large reversible capacity of 1536 MACH-1 and can maintain 100 cycles at 500 MACH-1.
Through theoretical calculations and the electrochemical detection of the electrochemical behavior at different stages of the cycle, it is revealed that the storage mechanism is subjected to 14-
Each C = N group has a lithium ion, and each benzene ring has an electronic oxidation-reduction chemistry of six lithium-ion bonded organic skeleton monomer.
This work may pave the way for the development of new technologies
Capacity electrodes for organic rechargeable batteries.
Application of lithium-ion batteries (LIBs)
Due to its wide application in portable electronic products and in high-
Electric cars.
Despite a lot of efforts in the synthesis of electrode materials, the rational design of lithium
Ion battery electrodes with high specific capacity and high power
Energy density and excellent stability remain a challenge.
Today, most of the research focuses on inorganic materials and their carbon-
Composite materials are involved.
It is recommended that organic electrode materials be used as alternative electrode candidates for the next stage
LIBs have unique advantages compared to inorganic analogs.
Potential low organic electrode material
Cost, recyclable and safe (Less heat release)
When completely discharged.
More importantly, understanding the active organic functional groups of effective lithium storage can enable molecules-
The horizontal design of the electrode and a large number of new electrodes can be developed.
In all types of organic electrode materials, as a potential high-
Capacity Cathode or anode material of lithiumion batteries.
Carbonyl base can be found in many different forms of organic compounds, while most of the explored carbonyl base-
The based electrodes are mainly based on quinone or derivatives of aromatic fatty acids.
In addition, some non-co. polymer or layered organic materials have also been explored as promising organic electrodes for LIBs.
However, the small reversible capacity, the dissolution of electrically active species into organic electrolyte and the poor conductivity of organic electrode materials are serious problems that limit the development of organic electrode materials.
Valence organic framework (COFs)
It is a subclass of micro-porous organic polymer with strong bond and atomic precise selfassembled two-or three-
Size form.
It has been widely used as functional materials such as gas adsorption, catalysis, super capacitor, proton conduction and semiconductor.
Two of them. dimensional (2D-)
Layered COFs demonstrates functionality
An electronic system in a layer for charge transfer and open channels along the direction of the layer stack.
Very few 2D so far
Layered COF materials with reversible lithium are reported
The storage capacity is about 100-800 of the library of electrode materials used when the mAh u2009 g.
However, the tightly stacked COFs 2D layer structure, especially in the way of heavy accumulation with strong interaction, results in lithium-
Even at high current density, ions penetrate into the internal active sites deeply buried between layers.
This will inevitably lead to redox-
Activity site, thereby reducing lithium-
Storage capacity of 2D COFs.
Similar to graphene materials stripped from graphite, mechanical stripping of layered organic structures is considered an effective strategy to solve this problem.
Here, the work shows a controlled increase in the number of people
Layered 2D COFs on carbon nanotubes (CNT)
For lithium-ion batteries.
In this way, COF is separated in situ by CNT during growth, and rarely-
Through the interaction between the two components, layered COF can be obtained around CNT. Lithium-
The storage redox reaction is not only related to the common C = N base, but also to the intriguing benzene ring (C=C)of the few-layered COF.
The efficient use of the six carbon atoms of the benzene ring to store six lithium ions resulted in a very large contribution to the capacity of the COF monomer after repeating 500 cycles.
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