Graphene-Anchored Mesoporous Mn–Co Oxide Battery-like Materials for Ultrahigh Performance Hybrid Supercapacitors

Abstract

The energy storage mechanism of hybrid supercapacitors originates mainly from Faradaic charge transfer generated on/near the surface of Faradaic pseudocapacitive materials. Therefore, the development of electrode materials with superior electron collection efficiency and energy storage capacity is urgently needed for supercapacitor applications. Herein, we design and synthesize battery-like Mn−Co oxide/rGO hybrid nanostructures via a facile twostep process. By introducing graphene, the structural properties of Mn−Co oxide (MnCoO) are effectively modified. In addition, benefiting from the Schottky barrier caused by the difference in work functions, free electrons are trapped and accumulated at the Fermi level, enabling Mn−Co oxide to obtain superior electron accumulation effect. The fabricated hybrid electrode exhibits enhanced energy storage performances, with ultrahigh specific capacitance of 2749 F g −1 (381.8 mAh g −1 ) and remarkable cycling durability of 95.7% retention over 8000 cycles at 10 A g −1 . When fabricated as an asymmetric supercapacitor (ASC), an excellent energy density of 35.5 Wh kg −1 at 1008.2 W kg −1 can be delivered for the MnCoO-rGO/NF//rGO/NF device. This study can offer guidance for constructing high-performance supercapacitors through interfacial electronic structure design.

Regulable Electron Transfer on ZnS/CoS2/CC Prepared by an MOF-on-MOF Strategy for Robust LIB Performance

“…At the charging process (Figure d), electrons can be temporarily captured and accumulated on the ZnS/CoS 2 /CC interface . These enriched electrons can effectively enhance the redox activity of CoS 2 and ZnS and improve the reversibility of the electrochemical process, thus creating a synergistic effect with an enhanced specific capacitance. , Furthermore, electrons that are captured during the discharge process can be freed (Figure e). As a result, the build-up of free charges on the ZnS/CoS 2 /CC interface could lead to the presence of an extra current density prior to the redox reaction, resulting in a higher reversible capacity. , Meanwhile, the large amount of charges accumulated on the CoS 2 surface will allow the reduction of the high-valent Co fraction and promote the CoS 2 reduction reaction, which can improve the electrochemical kinetics of ZnS/CoS 2 /CC.…”

A Facile One‐Pot Hydrothermal Synthesis of Zn, Mn Co‐Doped NiCo2O4 as an Efficient Electrode for Supercapacitor Applications

“…[1,2] To date, the ultracapacitors are eco-friendly with good cycling stability and having excellent power density than their counterparts like batteries, fuel cells, etc., which help them for fabricating hybrid vehicles and portable electronics. [3][4][5] The categories of supercapacitors (SCs) are classified based on their working principle, such as EDLC and Pseudocapacitors. In EDLC systems, the mesoscopic materials (carbon, Activated Carbon, Carbon nanotube, etc) are used due to their excellent redox active properties result in enhanced specific capacitance and very high power density nearly 10 5 Wh/Kg.…”

“…The development of portable, light weight, and efficient electronic devices with high energy and high power densities having long cycle life is the key challenge to the researchers to compensate the energy crisis [1,2] . To date, the ultracapacitors are eco‐friendly with good cycling stability and having excellent power density than their counterparts like batteries, fuel cells, etc., which help them for fabricating hybrid vehicles and portable electronics [3–5] . The categories of supercapacitors(SCs) are classified based on their working principle, such as EDLC and Pseudocapacitors.…”

Carbon Transition‐metal Oxide Electrodes: Understanding the Role of Surface Engineering for High Energy Density Supercapacitors

“…Although significant advances have been achieved in the development of high-performance supercapacitors, practical applications are far from being realized since supercapacitors developed thus far suffer from low energy density, poor rate capability, and inferior cycling stability during high current density condition process. Specific strategies have been proposed to tackle these problems, including the structural modifications of present electrode materials to increase the overall specific capacitance and the utilization of different nonalkaline electrolytes like organic, ionic liquid, or gel-electrolytes [137] Copyright 2019, American Chemical Society. to widen the operating potential window.…”

“…Furthermore, Zhu et al performed density functional theory (DFT) calculations to study the interfacial effect between MnCoO and rGO in as-prepared C-TMO hybrid electrode. [137] Figure 5(a-c) demonstrates the energy band diagrams at the interface of two components, which reveal that the free electrons in rGO interface can be trapped by MnCoO until the Fermi levels are aligned and the Schottky barrier is formed. These extra electrons on/near the surface of MnCoO could effectively improve the redox activity by gaining additional current density, thereby increasing the total specific capacitance.…”