Oxygen Defect Modulated Titanium Niobium Oxide on Graphene Arrays: An Open‐Door for High‐Performance 1.4 V Symmetric Supercapacitor in Acidic Aqueous Electrolyte

Abstract

Despite appealing supercapacitive properties, the acidic aqueous supercapacitors (SCs) are still suffering from low operating voltage (<1 V) leading to unsatisfactory energy densities. Herein, for the first time, it is reported that the oxygen defect modulated Ti 2 Nb 10 O 29−x (TNO x ) on interlinked graphene array (denoted as TNO x G) can achieve a wide potential window up to 1.8 V in 1 m H 2 SO 4 electrolyte and deliver an extremely high capacitance up to 368.9 F g −1 at 0.5 A g −1 . Accompanying the improved charge transfer efficiency and preferable H ion diffusion, the oxygen defects in TNO x G are capable of stimulating more pseudocapacitive behavior and simultaneously suppressing oxygen evolution reaction. Furthermore, a 1.4 V high voltage quasi-solid-state TNO x G-based symmetric supercapacitor is demonstrated, yielding a maximum energy density of 0.58 mWh cm −3 at a power density of 0.57 W cm −3 and exceptionally excellent cycling durability. It is believed that this strategy of oxygen defect modulation to optimize reaction kinetics will lead to further improvements in the performance of high-voltage aqueous SCs.

High areal capacitance of Fe3O4‐decorated carbon nanotubes for supercapacitor electrodes

“…The data are presented in a Ragone plot (Figure A), which indicate that relatively high power‐energy characteristics were obtained for the asymmetric device with high active mass. High power‐energy characteristics have also been reported in other investigations . It is important to note that specific capacitance, power density, and energy density decrease significantly with increasing active mass.…”

“…High powerenergy characteristics have also been reported in other investigations. [42][43][44] It is important to note that specific capacitance, power density, and energy density decrease significantly with increasing active mass. Therefore, good electrochemical performance at high active mass, achieved in our investigation, is promising for practical applications.…”

Boosting fast energy storage by synergistic engineering of carbon and deficiency

“…The TNO −x @C 3 shows the strongest EPR signal at g = 2.0 (typical signal of oxygen vacancies) ( Supplementary Fig. 9d), higher than those of TNO −x @C 1 and TNO −x @C 5 counterparts, while the pure TNO nanosheet sample only displays a flat line without obvious oxygen vacancy 23,24 . These results clearly confirm the presence of abundant oxygen deficiencies in TNO −x @C 3 .…”

Surface Engineering for Advanced Aqueous Supercapacitors: A Review

“…Therefore, considerable attention has been focused on the supercapacitors (SCs) due to their large power density and excellent cycling stability, which makes it more suitable for high‐power applications . Aqueous electrolyte based SCs are attractive because of their excellent power output, much longer cycle life, superior safety, low‐cost, and environmental friendliness . Nevertheless, the lower energy densities ( E ) of aqueous SCs as compared to batteries have impeded their range of commercial applications .…”

“…[12][13][14] Aqueous electrolyte based SCs are attractive because of their excellent power output, much longer cycle life, superior safety, low-cost, and environmental friendliness. [15][16][17] Nevertheless, the lower energy densities (E) of aqueous SCs as compared to batteries have impeded their range of commercial applications. [18] According to the theoretical equation, E = (1/2) CV 2 , the E is directly determined by the capacitance (C) and the square of potential (V), which are two main focuses for nowadays researchers.…”