# Porous Doped Carbons from Anthracite for High-Performance Supercapacitors
## 4 Conclusions  
In summary, we demonstrate a tractable KOH activation route toward the scalable production of the porous N-doped carbon from naturally available and low-cost anthracite biomass as electrode materials for supercapacitors. This synthetic approach can result in the functionalized carbon materials with some pivotal superiorities: (1) a good textural development (for example, colossal BET surface areas up to 2814 m\({}^{2}\) g\({}^{-1}\) and pore volumes as high as 1.531 cm\({}^{3}\) g\({}^{-1}\)), (2) multiscale porosity (mixture of predominant micropore of 1-2 nm and small-sized mesopores of 2-4 nm), and (3) proper nitrogen dopant content (2.77 at%). The optimal porous doped carbon can impart good supercapacitive performance with a great specific capacitance of 325 F g\({}^{-1}\) at 0.5 A/g, decent rate capability, and stable cyclic lifetime even after 5000 consecutive cycles at 10 A g\({}^{-1}\) (92% capacity retention). As a result, the assembled symmetric SC in 1 mol L\({}^{-1}\) Na\({}_{2}\)SO\({}_{4}\) aqueous electrolyte can well work at 1.8 V to deliver a superior energy density of 23.5 Wh kg\({}^{-1}\) at a power density of 450 W kg\({}^{-1}\) and to still maintain 12.5 Wh kg\({}^{-1}\) at 9000 W kg\({}^{-1}\). All characterizations verify that the greatly improved electrochemical behavior can benefit from excellent mass/charge transportation and ample heteroatom active sites. The wieldy one-step KOH activation technique can act as a potential strategy for the massive production of anthracite-derived multifunctional nanocarbon materials for a catholic  
Figure 11: Electrochemical measurements of the as-assembled KAC-800 symmetric supercapacitor in 1 M Na\({}_{2}\)SO\({}_{4}\) electrolyte: (**a**) CV curves of the cell operated in different operation voltages at a scan rate of 50 mV s\({}^{-1}\); (**b**) CV curves of the cell at various scan rates. (**c**) GCD curves of the cell at various current densities; (**d**) capacitances of KAC-800 electrode at various current densities. The inset shows the Ragone plot.  
cascade of energy storage systems where the homogeneous small pores and proper dopants do carry great clout with energy storage mechanism.  
The following are available online at [[http://www.mdpi.com/2076-3417/10/3/1081/s1](http://www.mdpi.com/2076-3417/10/3/1081/s1)]([http://www.mdpi.com/2076-3417/10/3/1081/s1](http://www.mdpi.com/2076-3417/10/3/1081/s1)), Figure S1: PSD of samples, Figure S2: N\({}_{2}\) adsorption-desorption isotherm of KAC-800-900, Figure S3: PSD of KAC-800-900, Figure S4: XRD pattern of KAC-800-900, Figure S5: DTG curves of KAC-800 and KAC-800-900, Table S1: The proximate analysis and element analysis data of anthracite, Table S2: Textural properties of KAC-800-900 (Calculated total surface area Sget, total pore volume V\({}_{\rm T}\), average pore diameter d\({}_{\rm M}\)), Table S3: Textural properties and chemical composition of KAC-800 and KAC-800-900 (atomic percent of elements obtained from XPS analysis).  
Conceptualization, J.D. and Z.P.; investigation, J.D. and Z.P.; writing--original draft preparation, J.D. and Z.P.; writing--review and editing, Z.X. and S.S.; supervision, H.D. and L.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (21806015).  
We deeply thank [PERSON] in Sichuan University for the great support and help.  
The authors declare no conflict of interest.