Bridging Monolayer MXenes With PEDOT:PSS for High-Mass-Loading Ultrahigh-Rate Supercapacitors

Supercapacitors with high mass loadings (>10 mg cm^{- 2}) typically struggle to deliver ultrahigh-rate performance because of sluggish mass and charge transport. This challenge is further exacerbated when using 2D electrode materials, which tend to undergo random self-restacking driven by weak interlayer interactions. Here, we report a unilaminating and bridging strategy to construct ordered poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-bridged Ti₃C₂T_x MXene (sMX-PP) by finely modulating these weak interactions. The bridging mechanism arises from hydrogen bonding and electrostatic interactions between PEDOT:PSS and single-layer Ti₃C₂T_x, effectively preventing restacking and promoting ion/electron transport. As a result, the sMX-PP electrode with a high mass loading of 11.2 mg cm^-2 delivers a specific capacitance of 165 F g^-1 at an ultrahigh current density of 100 A g^-1. Furthermore, asymmetric supercapacitors assembled with activated carbon retain 58% of their capacitance as the current density increases from 3 to 70 A g^-1. This work provides a feasible approach to mitigating the performance degradation of MXene electrodes under simultaneous ultrahigh-rate and high-mass-loading conditions, thus advancing the practical deployment of supercapacitors in ultrahigh-power applications.