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Constructing heterostructure in nanomaterials is a scientific and efficient method to optimize the electrochemical properties of supercapacitors. Carbon aerogels (CAs) can enhance electrical conductivity and ion diffusion because of their three-dimensional porous structure, which is useful for fabricating electrodes. The moderate nanoheterostructures in aerogel nanomaterials have made great contributions to the optimization of application performance. Herein, a simple method for constructing the MnO2 nanoparticle/CA (MnO2/CA) heterostructure is proposed. The MnO2/CA heterostructure exhibits outstanding electrochemical capability in a three-electrode system, with a specific capacitance of 384 F/g, higher than 201 F/g of the CA, at a current density of 0.5 A/g. When MnO2/CA is used as a symmetric supercapacitor, it also exhibits a high energy density and power density, with the highest energy density of 33.78 Wh/kg. The prepared MnO2/CA shows improved performance for synergies in providing a high specific capacity and long cycle life. [ABSTRACT FROM AUTHOR]

• The carbon source is the puffball spore with natural hollow sphere structure. • N, S self-doped hollow-sphere porous carbon is obtained via direct carbonization/activation. • The NS-HPC-4 electrode offers a high specific capacitance of 285F/g at 0.5 A/g. • NS-HPC-4 based supercapacitor yields an energy density of 58.4 Wh/kg in Et 4 NBF 4 /AN electrolyte. A novel N, S self-doped hollow-sphere porous carbon is directly prepared from abundant biomass puffball spores via a simple carbonization and KOH activation process for the first time. The electrochemical properties and porous structure of these carbons are explored by adjusting the amount of KOH. It is found that the obtained N, S self-doped hollow-sphere porous carbon with a KOH to carbon mass ratio of 4 (NS-HPC-4) exhibits the largest specific surface area (1431 m2/g), a well-developed hierarchical porous structure and moderate N/S contents. As a result, the NS-HPC-4 electrode in the supercapacitor delivers a large specific capacitance of 285 F/g at 0.5 A/g in KOH electrolyte. Furthermore, the symmetric supercapacitor based on NS-HPC-4 exhibits an energy density of 10.9 Wh/kg at a power density of 400.4 W/kg in 2 M KOH aqueous electrolyte, and achieves a high energy density of 58.4 Wh/kg at a high power density of 876.0 W/kg in 1 M Et 4 NBF 4 /AN organic electrolyte. These excellent results confirm that puffball spores derived porous carbons are promising candidates to be used in high performance supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • SAM aerogel is prepared by directional freeze-drying method. • Tuning carbonization temperature and activator ratio to optimize performance. • SAM-700-4 shows 3D interconnected structure with large specific surface area. • SAM-700-4 shows excellent specific capacitance of 441.80 F/g at 0.5 A/g. • SAM-700-4//SAM-700-4 all-solid-state supercapacitor exhibit high energy density. Hierarchical porous carbon shows great potential in the field of energy storage due to high porosity, large surface area, and excellent electrical conductivity. Here, we successfully fabricated carbon aerogel derived from sodium alginate/melamine composite (SAM) by directional freeze-drying combined with simple carbonization and activation process. The optimal SAM-700-4 possesses a high nitrogen (5.67 at.%) and oxygen (8.98 at.%) contents along with high specific surface area of 2577.62 m2/g and unique directional channel structure. Due to their synergistic effect, the SAM-700-4 electrode exhibits a high specific capacitance of 441.80 F/g at a current density of 0.5 A/g. Interestingly, the all-solid-state symmetric supercapacitor based on SAM-700-4//SAM-700-4 in PVA/SA/KOH gel electrolyte has a large energy density of 20.87 Wh/kg at a power density of 4000 W/kg and exhibits excellent cycling stability. It is believed that this N, O co-doped directional hierarchical porous carbon aerogel may show promising prospects as advanced energy storage materials. [ABSTRACT FROM AUTHOR]

• Cellulose derived carbon aerogel coated by PANI used as a scaffolding framework. • ZIF-8 derived porous carbon (ZC) is anchored into PCA carbon framework. • ZPCA carbon composite has a high specific surface area and large N contents. • ZPCA carbon composite yield a large specific capacitance of 388 F g−1 at 0.5 A g−1. • The symmetric device shows ultrahigh energy density in 1 M Et 4 NBF 4 /AN electrolyte. Cellulose derived carbon aerogel (CA) with unique three-dimensional network coated with polyaniline (PANI) on its surface is used as a scaffolding framework to anchor ZIF-8. The designed ZIF-8 derived porous carbon (ZC)/PANI@CA (ZPCA) hybrid carbon composite through a facile solution immersion chemical route and subsequent carbonization process is employed as electrode for supercapacitor, which has contributed a large specific surface area, a hierarchical porous structure and reasonable N content (up to 6.27 at.%). The synthesized ZPCA electrode achieves an outstanding capacitance of 388 F g−1 at 0.5 A g−1 as well as an excellent cycling performance. More inspiringly, the symmetric supercapacitor based ZPCA achieves a high energy density of 13.4 Wh kg−1 at a power density of 250 W kg−1 using 2 M KOH aqueous solution, and an ultrahigh energy density of 81.8 Wh kg−1 at a power density of 950 W kg−1 is realized using Et 4 NBF 4 /AN electrolyte. [ABSTRACT FROM AUTHOR]