Boosting the Electrical Double‐Layer Capacitance of Graphene by Self‐Doped Defects through Ball‐Milling

Abstract

Improving the capacitance of carbon materials for supercapacitors without sacrificing their rate performance, especially volumetric capacitance at high mass loadings, is a big challenge because of the limited assessable surface area and sluggish electrochemical kinetics of the pseudocapacitive reactions. Here, it is demonstrated that "self-doping" defects in carbon materials can contribute to additional capacitance with an electrical double-layer behavior, thus promoting a significant increase in the specific capacitance. As an exemplification, a novel defect-enriched graphene block with a low specific surface area of 29.7 m 2 g −1 and high packing density of 0.917 g cm −3 performs high gravimetric, volumetric, and areal capacitances of 235 F g −1 , 215 F cm −3 , and 3.95 F cm −2 (mass loading of 22 mg cm −2 ) at 1 A g −1 , respectively, as well as outstanding rate performance. The resulting specific areal capacitance reaches an ultrahigh value of 7.91 F m −2 including a "self-doping" defect contribution of 4.81 F m −2 , which is dramatically higher than the theoretical capacitance of graphene (0.21 F m −2 ) and most of the reported carbon-based materials. Therefore, the defect engineering route broadens the avenue to further improve the capacitive performance of carbon materials, especially for compact energy storage under limited surface areas.

Orchestrating a Controllable Engineering of Dual‐Model Carbon Structure in Si/C Anodes

“…In contrast, the feature A at 288.5 eV between 𝜋* and 𝜎* bands corresponds to the structural change resulting from the increase of the sp 3 -like structure and C-H at the edge or defect site. [36,55] With the increase in pyrolysis temperature, the decrease in the intensity of feature A indicates a reduction in the defect content of the carbon component in PySi/C, which is in full accordance with the TEM results. Furthermore, given that the carbon is doped with nitrogen atoms, the impact of high temperature on the oxidation of the carbon component can be assessed by examining alterations in nitrogen bonding.…”

Orchestrating a Controllable Engineering of Dual‐Model Carbon Structure in Si/C Anodes

“…In contrast, the feature A at 288.5 eV between 𝜋* and 𝜎* bands corresponds to the structural change resulting from the increase of the sp 3 -like structure and C-H at the edge or defect site. [36,55] With the increase in pyrolysis temperature, the decrease in the intensity of feature A indicates a reduction in the defect content of the carbon component in PySi/C, which is in full accordance with the TEM results. Furthermore, given that the carbon is doped with nitrogen atoms, the impact of high temperature on the oxidation of the carbon component can be assessed by examining alterations in nitrogen bonding.…”

Pseudocapacitive Potassium‐Ion Intercalation Enabled by Topologically Defective Soft Carbon toward High‐Rate, Large‐Areal‐Capacity, and Low‐Temperature Potassium‐Ion Batteries

“…[42] D 1 band is related to the carbon atoms located at the edge of graphite sheets, and D 2 band is assigned to the in-plane non-hexagonal defects, while D 3 band is originated from the sp 3 -boned carbon atoms; G band is corresponded to sp 2 -hybridized graphitic carbon atoms. [43,44] According to the Tuinstra-Koenig equation (L a = 4I G /I D1 ), [45] the lateral average size of graphite-like microcrystals (L a ) of SC, TDSC, and HC are 3.029, 2.543, and 2.363 nm (Figure 3b), respectively, which is in accordance with the HRTEM and XRD results. In comparison with SC, the shortened size of microcrystals of TDSC can reduce the resistance of K-ion insertion deeply inside the carbon layers.…”

Controllable synthesis of electric double-layer capacitance and pseudocapacitance coupled porous carbon cathode material for zinc-ion hybrid capacitors

“…All four samples were amorphous carbons and showed two broad diffraction peaks at 23.3°and 44°, representing (002) and (100) crystal planes, respectively. A slight shift to the left of the peak at 23.3° indicated an increase in the layer space, 52,53 which corresponded to the results of HRTEM. The intensity ratio of the D band and G band of Raman spectra represented the graphitization degree of different samples.…”

Orchestrating a Controllable Engineering of Dual‐Model Carbon Structure in Si/C Anodes

“…In contrast, the feature A at 288.5 eV between 𝜋* and 𝜎* bands corresponds to the structural change resulting from the increase of the sp 3 -like structure and C-H at the edge or defect site. [36,55] With the increase in pyrolysis temperature, the decrease in the intensity of feature A indicates a reduction in the defect content of the carbon component in PySi/C, which is in full accordance with the TEM results. Furthermore, given that the carbon is doped with nitrogen atoms, the impact of high temperature on the oxidation of the carbon component can be assessed by examining alterations in nitrogen bonding.…”

Pseudocapacitive Potassium‐Ion Intercalation Enabled by Topologically Defective Soft Carbon toward High‐Rate, Large‐Areal‐Capacity, and Low‐Temperature Potassium‐Ion Batteries

“…[42] D 1 band is related to the carbon atoms located at the edge of graphite sheets, and D 2 band is assigned to the in-plane non-hexagonal defects, while D 3 band is originated from the sp 3 -boned carbon atoms; G band is corresponded to sp 2 -hybridized graphitic carbon atoms. [43,44] According to the Tuinstra-Koenig equation (L a = 4I G /I D1 ), [45] the lateral average size of graphite-like microcrystals (L a ) of SC, TDSC, and HC are 3.029, 2.543, and 2.363 nm (Figure 3b), respectively, which is in accordance with the HRTEM and XRD results. In comparison with SC, the shortened size of microcrystals of TDSC can reduce the resistance of K-ion insertion deeply inside the carbon layers.…”

Controllable synthesis of electric double-layer capacitance and pseudocapacitance coupled porous carbon cathode material for zinc-ion hybrid capacitors

“…All four samples were amorphous carbons and showed two broad diffraction peaks at 23.3°and 44°, representing (002) and (100) crystal planes, respectively. A slight shift to the left of the peak at 23.3° indicated an increase in the layer space, 52,53 which corresponded to the results of HRTEM. The intensity ratio of the D band and G band of Raman spectra represented the graphitization degree of different samples.…”

Orchestrating a Controllable Engineering of Dual‐Model Carbon Structure in Si/C Anodes

“…In contrast, the feature A at 288.5 eV between 𝜋* and 𝜎* bands corresponds to the structural change resulting from the increase of the sp 3 -like structure and C-H at the edge or defect site. [36,55] With the increase in pyrolysis temperature, the decrease in the intensity of feature A indicates a reduction in the defect content of the carbon component in PySi/C, which is in full accordance with the TEM results. Furthermore, given that the carbon is doped with nitrogen atoms, the impact of high temperature on the oxidation of the carbon component can be assessed by examining alterations in nitrogen bonding.…”

Pseudocapacitive Potassium‐Ion Intercalation Enabled by Topologically Defective Soft Carbon toward High‐Rate, Large‐Areal‐Capacity, and Low‐Temperature Potassium‐Ion Batteries

“…[42] D 1 band is related to the carbon atoms located at the edge of graphite sheets, and D 2 band is assigned to the in-plane non-hexagonal defects, while D 3 band is originated from the sp 3 -boned carbon atoms; G band is corresponded to sp 2 -hybridized graphitic carbon atoms. [43,44] According to the Tuinstra-Koenig equation (L a = 4I G /I D1 ), [45] the lateral average size of graphite-like microcrystals (L a ) of SC, TDSC, and HC are 3.029, 2.543, and 2.363 nm (Figure 3b), respectively, which is in accordance with the HRTEM and XRD results. In comparison with SC, the shortened size of microcrystals of TDSC can reduce the resistance of K-ion insertion deeply inside the carbon layers.…”

Controllable synthesis of electric double-layer capacitance and pseudocapacitance coupled porous carbon cathode material for zinc-ion hybrid capacitors

“…All four samples were amorphous carbons and showed two broad diffraction peaks at 23.3°and 44°, representing (002) and (100) crystal planes, respectively. A slight shift to the left of the peak at 23.3° indicated an increase in the layer space, 52,53 which corresponded to the results of HRTEM. The intensity ratio of the D band and G band of Raman spectra represented the graphitization degree of different samples.…”