Alternative‐Ultrathin Assembling of Exfoliated Manganese Dioxide and Nitrogen‐Doped Carbon Layers for High‐Mass‐Loading Supercapacitors with Outstanding Capacitance and Impressive Rate Capability

Abstract

Manganese dioxide (MnO 2 ) materials have received much attention as promising pseudocapacitive materials owing to their high theoretical capacitance and natural abundance. Unfortunately, the charge storage performance of MnO 2 is usually limited to commercially available mass loading electrodes because of the significantly lower electron and ion migration kinetics in thick electrodes. Here, an alternatively assembled 2D layered material consisting of exfoliated MnO 2 nanosheets and nitrogen-doped carbon layers for ultrahighmass-loading supercapacitors without sacrificing energy storage performance is reported. Layered birnessite-type MnO 2 is efficiently exfoliated and intercalated by a carbon precursor of dopamine using a fluid dynamic-induced process, resulting in MnO 2 /nitrogen-doped carbon (MnO 2 /C) materials after self-polymerization and carbonization. The alternatively stacked and interlayer-expanded structure of MnO 2 /C enables fast and efficient electron and ion transfer in a thick electrode. The resulting MnO 2 /C electrode shows outstanding electrochemical performance at an ultrahigh mass loading of 19.7 mg cm −2 , high gravimetric and areal capacitances of 480.3 F g −1 and 9.4 F cm −2 at 0.5 mA cm −2 , and rapid charge/discharge capability of 70% capacitance retention at 40 mA cm −2 . Furthermore, asymmetric supercapacitor based on high-mass-loading MnO 2 /C can deliver an extremely high energy of 64.2 Wh kg −1 at a power density of 18.8 W kg −1 in an aqueous electrolyte.

Oxygen-Containing Functional Groups Regulating the Carbon/Electrolyte Interfacial Properties Toward Enhanced K+ Storage

“…It has been widely demonstrated that doping heteroatoms (such as N, S or P) are an effective approach to regulate physical and chemical properties, including bonding schemes, electronic structure, defects or ion adsorption ability, and thus improve the electrochemical properties of carbonaceous materials [6][7][8]. This strategy has been proven to be effective in energy storage applications (e.g., lithium/ sodium-ion batteries, supercapacitors and oxygen reduction/evolution reaction (ORR/OER)) [9][10][11][12]. In the aspect of K + energy storage systems, heteroatoms-doped carbon fibers [1], graphene [13] or hard carbon [14] exhibit excellent cyclability and rate performance.…”

Efficient coupling of MnO2/TiN on carbon cloth positive electrode and Fe2O3/TiN on carbon cloth negative electrode for flexible ultra-fast hybrid supercapacitors

“…One possible means to improve the electrical conductivity and specific area of MnO 2 is to produce nanostructured MnO 2 thin films on conductive carbon-based materials, nanowires, nanosheets, or conductive polymers, for example, MnO 2 /nitrogen-doped carbon, 8 N + MnO 2 @TiC/CC, 9 MnO 2 /CuCo 2 O 4 , 10 and γ-MnO 2 /PANI. 11 In this work, a novel composite structure composed of MnO 2 ultrathin nanosheet is prepared on the TiN nanowire array on a piece of conductive carbon cloth (MnO 2 /TiN/CC) to form a binder-free and flexible positive electrode for supercapacitors as shown in Fig.…”

Oxygen deficient α-MoO3 with enhanced adsorption and state-quenching of H2O for gas sensing: a DFT study

“…Two-dimensional (2D) transition metal oxides (TMOs) have received considerable attention owing to their distinctive electronic properties as well as high specific surface area and rich active surface sites. 1–6 Orthorhombic phase α-MoO 3 , a stable layered TMO, has been widely used as an anode material for ion batteries ( e.g. , H + , Li + , and Zn 2+ ) and supercapacitors due to its multiple valence states and unique layered structure.…”