Synthesis and Enhancement of Electroactive Biomass/Polypyrrole Hydrogels for High Performance Flexible All‐Solid‐State Supercapacitors

Abstract Recently, electroactive biomass‐based hydrogels have attracted great attention for flexible supercapacitor electrodes due to its porous, renewable, earth‐abundant, low‐cost, and environmentally friendly characters. However, it is challenging to facilely prepare biomass‐based hydrogels with simultaneously possesses high mechanical strength and excellent electrochemical performance. In this work, the lignosulfonate/polypyrrole (Lig/PPy) hydrogel (LP 54 ) is obtained. In order to further improve the mechanical strength and electrochemical performance of LP 54 , functionalized porous carbon nanospheres/lignosulfonate/polypyrrole hydrogel (FPCSLP 54 ) is prepared by introducing a trace of FPCS (≈4.5 wt%) fabricated by hydrothermal treatment the mixture of PCS and pyrrole into the prepared LP 54 system. FPCS can be uniformly anchored into Lig/PPy framework. The LP 54 and FPCSLP 54 exhibit compressive strength of 6.0 and 9.3 kPa with the water content of 94.9% and 94.3%, respectively. Meanwhile, as‐prepared LP 54 and FPCSLP 54 are separately assembled into symmetric flexible supercapacitors with cellulose/H 2 SO 4 hydrogel electrolytes, which exhibit superior areal capacitance (463 and 522 mF cm −2 ), good rate capability and outstanding energy density (41.2 and 72.5 µWh cm −2 ). Remarkably, flexible supercapacitors present outstanding electrochemical stability even suffering 1000 bending cycles. In this work, the strategy to construct electroactive biomass‐based hydrogels is contributed and a new method to enhance the properties of hydrogels is provided.