Reduced graphene oxide promoted assembly of graphene@polyimide film as a flexible cathode for high-performance lithium-ion battery

Organic carbonyl polymers have been gradually used as the cathode in lithium-ion batteries (LIB). However, there are some limits in most organic polymers, such as low reversible capacity, poor rate performance, cycle instability, etc. , due to low electrochemical conductivity. To mitigate the limits, we propose a strategy based on polyimide (PI)/graphene electroactive materials coated with reduced graphene oxide to prepare a flexible film (G@PI/RGO) by solvothermal and vacuum filtration processes. As a flexible cathode for LIB, it provides a reversible capacity of 198 mA h g −1 at 30 mA g −1 and excellent rate performance of 100 mA h g −1 at high current densities of 6000 mA g −1 , and even a super long cycle performance (2500 cycles, 70% capacity retention). The excellent performance results in a special layer structure in which the electroactive PI was anchored and coated by the graphene. The present synthetic method can be further applied to construct other high-performance organic electrodes in energy storage. G@PI/RGO is prepared by a combination of solvothermal reaction and carbonization. With good mechanical flexibility and high conductivity, it shows excellent performance when directly used as the cathode for LIB.