Advanced three-dimensional hierarchical porous α-MnO₂ nanowires network toward enhanced supercapacitive performance

Abstract

Hierarchical α-MnO2 nanowires with oxygen vacancies grown on carbon fiber have been synthesized by a simple hydrothermal method with the assistance of Ti4+ ions. Ti4+ ions play an important role in controlling the morphology and crystalline structure of MnO2. The morphology and structure of the as-synthesized MnO2 could be tuned from δ-MnO2 nanosheets to hierarchical α-MnO2 nanowires with the help of Ti4+ ions. Based on its fascinating properties, such as many oxygen vacancies, high specific surface area and the interconnected porous structure, the α-MnO2 electrode delivers a high specific capacitance of 472 F g-1 at a current density of 1 A g-1 and the rate capability of 57.6% (from 1 to 16A g-1). The assembled symmetric supercapacitor based on α-MnO2 electrode exhibits remarkable performance with a high energy density of 44.5 Wh kg-1 at a power density of 2.0 kW kg-1 and good cyclic stability (92.6% after 10000 cycles). This work will provide a reference for exploring and designing high-performance MnO2 materials.

Electrochemical Analysis of MnO2 (α, β, and γ)-Based Electrode for High-Performance Supercapacitor Application

“…Fuel cells/batteries provide high energy densities, and capacitors offer high power densities. In this regard, supercapacitors and electrochemical capacitors satisfy power (high power densities related to batteries) and energy (high energy densities related to capacitors) requirements [2]. In supercapacitors, two mechanisms (electric double-layer capacitance (EDLC) and pseudocapacitance) occur at the electrode-electrolyte interface and provide sufficient specific capacitance [3].…”