Porous Mo–Co–S Nanosheets on Carbon Cloth for All‐Solid‐State Flexible Asymmetric Supercapacitors

Abstract

Abstract High‐performance and flexible supercapacitors (SCs) have great potential for powering wearable and portable devices. Herein, Mo‐doped Co 9 S 8 porous nanosheets on carbon cloth (denoted as Mo–Co–S/CC) are prepared for all‐solid‐state flexible asymmetric SCs via a two‐step method. Na 2 MoO 4 is selected as both Mo source and etching agent to create Mo‐doped porous structure, which provides plenty of reaction sites contributing to the decrease of electrochemical barrier and increase of electrochemical performances. The Mo–Co–S/CC electrode demonstrates a high specific capacity of 771.5 F g −1 at 2 A g −1 , excellent rate capability of 660.0 F g −1 at 20 A g −1 , and 109% cycling capacitance retention after 30 000 cycles. By using poly(vinyl alcohol)/KOH (PVA/KOH) gel as electrolyte, a flexible all‐solid‐state asymmetric supercapacitor (Mo–Co–S/CC//KOH//AC/CC, FASCs) is assembled, which can work under different bending angles and deliver a specific capacitance of 37.37 F g −1 at 1 A g −1 . Furthermore, the FASCs can deliver a maximum energy density of 14.68 Wh kg −1 at power density of 369 W kg −1 , with the capacity retention of 80.07% over 30 000 cycles at a high rate of 20 A g −1 .