Abstract
Two corncob-derived carbon electrode materials mainly composed of micropores (activated carbon, AC) and mesopores/macropores (corncob carbon, CC) were prepared and studied after the anodic electrodeposition of MnO2. The capacity of the MnO2/activated carbon composite (MnO2@AC) electrode did not noticeably increase after MnO2 electrodeposition, while that of the MnO2/corncob carbon composite (MnO2@CC) electrode increased up to 9 times reaching 4475 mF cm−2. An asymmetric all-solid-state supercapacitor (ASC) was fabricated using AC as the anode, MnO2@CC as the cathode, and polyvinyl alcohol (PVA)/LiCl gel as the electrolyte. An ultrahigh specific capacitance of 3455.6 mF cm−2 at 1 mA cm−2, a maximum energy density of 1.56 mW h cm−2, and a long lifetime of 10,000 cycles can be achieved. This work provides insights in understanding the function of MnO2 in biomass-derived electrode materials, and a green path to prepare an ASC from waste biomass with excellent electrochemical performance.
Highlights
Carbonaceous materials derived from abundant waste biomass [1,2,3,4,5,6,7,8] are considered as good electrode materials for supercapacitors due to their high specific surface area, good conductivity, easy accessibility, low cost, and renewability
We found that the effect of MnO2 highly depends on the architecture of the carbon carbon materials
We found that the effect of MnO2 highly depends on the architecture of the carbon materials
Summary
Carbonaceous materials derived from abundant waste biomass (sugarcane bagasse, potato, lotus seedpod, rice husk, taro epidermis, banana peel, mulberry leaves, coffee grounds, etc.) [1,2,3,4,5,6,7,8] are considered as good electrode materials for supercapacitors due to their high specific surface area, good conductivity, easy accessibility, low cost, and renewability. Microstructure design mainly pays attention to constructing a hierarchical pore structure of the carbon material using improved pretreatment and carbonization processes [13], while the other strategies concentrate on the introduction of pseudocapacitive materials such as heteroatoms [14,15], conducting polymers [16,17], transition metal sulfides [18], and oxides [19,20,21,22,23,24] Among these pseudocapacitive materials, manganese dioxide (MnO2 ) is the most promising one due to its high theoretical specific capacitance (1370 F g−1 ), wide potential window, rich reserves, and being environmentally friendly [25].
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