Polyimide/Graphene Composite Electrode Material Used In Lithium/Sodium Ion Batteries

With the continuous development of green energy,organic positive electrodes,especially conjugated carbonyl polymers,have been developed and used due to their high theoretical capacity,fast reaction kinetics,mechanical flexibility,environmental sustainability and structural diversity.A promising alternative to inorganic positive electrodes for rechargeable lithium / sodium ion batteries.However,due to the inherent electrical insulation of conjugated carbonyl polymers,achieving high capacity,high rate capability and long cycle life is a huge challenge.Based on this,this thesis revolves around the electrochemically active polyimide and graphene materials with excellent electrical conductivity,and used as electrode materials for electrochemical energy storage.The main research contents are as follows: 1.Flexible polyimide/ graphene film material(G@PI-NT/RGO): using 1,4,5,8-naphthalenetetracarboxylic dianhydride(NTCDA)as a synthetic monomer to prepare a film-like structure Composite materials.The film-like material has good mechanical flexibility and is directly applied to the positive electrode of a lithium-ion battery after being cut,showing a high specific capacity(171.2 m Ah g-1 at a current density of 30 m A g-1)and an ultra high rate The performance(high current density of 97.6 m Ah g-1 at 6000 m A g-1)and ultra-long cycle stability(with a capacity retention rate of nearly 70% after 2500 c ycles)indicate that the material has good application prospects.2.Three-dimensional structure polyimide / graphene composite material(G@PI-PT): using 3,4,9,10-perylenetetracarboxylic dianhydride(PTCDA)as the synthetic monomer,assembled in one step by s olvothermal The method of making polyimide grow uniformly in the three-dimensional graphene frame structure.The material is directly applied to the positive electrode of sodium ion battery after compression,and it shows ultra-high specific capacity(current density of 117.2 m Ah g-1 at 30 m A g-1)and excellent cycle stability(100.04 m Ah g-1 after 800 cycles)and reached a capacity retention rate of 85.5%.