Pseudocapacitive Enhancement for Layered PI@MXene Porous Organic Cathode in Advanced Lithium-Ion Batteries

A novel layered porous organic cathode was designed/fabricated by the utilization of few-layered MXene as matrix to facilitate the electron transport and porous polyimide (PI) as coating to supply lots of active carbonyl groups (shorten as PI@MXene). The bonding structure of the as-synthesized samples was tested by FTIR spectrum. And the existence of few-layered MXene in the samples was confirmed by XRD analysis. Moreover, the surface morphologies of PI@MXene were demonstrated by SEM images. The PI@MXene with 5 wt.% MXene showed the layered structure with porous PI on the surface of few-layered MXene. The EIS spectra verified the PI@5%MXene battery with the low EIS impedances (~42 Ω) owing to the existence of few-layered MXene. Therefore, the PI@5%MXene cell showed a good cycling stability and an excellent rate performance, which was assigned to the enhanced faster Li-ion diffusion and pseudocapacitive effects confirmed by GITT testing and kinetic calculations from the CV curves respectively. Thus, novel layered PI@MXene porous electrode material with fast electron transport, fast Li+ diffusion and enhanced pseudocapacitive effects to supply numerous active carbonyl sites deserved excellent electrochemical performances. This work may provide a promising strategy for the development of high-performance polyimide hybrid electrodes.