Corn Stalk-Based Carbon Microsphere/Reduced Graphene Oxide Composite Hydrogels for High-Performance Symmetric Supercapacitors

Herein, carbon microspheres (CSs) of relatively uniform size from waste biomass corn stalks without carbonization or activation were first inserted as spacers to inhibit the restacking of graphene sheets in carbon microsphere/reduced graphene oxide composite hydrogels (CS/rGOs). The prepared composite hydro-gels were applied as electrode materials for supercapacitors and exhibited excellent electrochemical performance due to their abundant oxygen-containing functional groups and good hydrophilicity. Notably, the CS/rGO-3 sample-based symmetric supercapacitors showed an excellent specific capacitance (281.5 F g(-1) at 0.3 A g(-1)), a good rate performance (81.87%), and an eminent capacitance retention rate (102.2% after 10,000 cycles at 10 A g(-1)). Considering the commercial value of corn stalks and their role in the field of carbon neutralization at the same time, this work affords a new strategy for the high value-added conversion of waste biomass and the preparation of high-performance supercapacitor electrode materials.