All-MXenes zinc ion hybrid micro-supercapacitor with wide voltage window based on V2CTx cathode and Ti3C2Tx anode

To further improve the electrochemical performance for the wearable and microelectronic devices, we reported an all-MXenes zinc ion hybrid micro-supercapacitor (ZIHMSC) with a wide voltage window (1.60 V) based on V2CTx as the cathode and Ti3C2Tx as the anode. The flexible V2CTx and Ti3C2Tx electrodes are fabricated by the electrophoretic deposition method, which is simple and conducive to the realization of positive and negative electrodes matching. Benefiting from the synergistic effect of the two MXenes and the unique configuration, our ZIHMSCs also achieve fast ion and electron transfer kinetics, showing better rate capability than the MXene/Zn system. And the ZIHMSCs achieve excellent electrochemical performance, with high area capacitance of 200.1 mF cm−2, well stability over 5,000 charge/discharge cycles, and high energy density of 71.6 μWh cm−2 at 400.7 μW cm−2. The reason for the wide voltage window of the ZIHMSC was well revealed by the large work function difference between the two electrode materials of V2CTx and Ti3C2Tx and the redox potential of the electrolyte. And the electrochemical energy storage mechanisms are well investigated by ex-situ XPS and XRD. In addition, the ZIHMSC displays well flexibility and mechanical property, suffering from 15,000 bending cycles under 90°. The ZIHMSCs can successfully drive digital tubes and meters and enable digital meters to operate for more than 600 s, proving their practical application potential.