Synthesis and Electrochemical Properties of Spin-Capable Carbon Nanotube Sheet/MnO_x Composites for High-Performance Energy Storage Devices

Abstract

Inspired by the high specific capacitances found using ultrathin films or nanoparticles of manganese oxides (MnO(x)), we have electrodeposited MnO(x) nanoparticles onto sheets of carbon nanotubes (CNT sheets). The resulting composites have high specific capacitances (C(sp) ≤ 1250 F/g), high charge/discharge rate capabilities, and excellent cyclic stability. Both the C(sp) and rate capabilities are controlled by the average size of the MnO(x) nanoparticles on the CNTs. They are independent of the number of layers of CNT sheets used to form an electrode. The high-performance composites result from a synergistic combination of large surface area and good electron-transport capabilities of the MnO(x) nanoparticles with the good conductivity of the CNT sheets. Such composites can be used as electrodes for lithium batteries and supercapacitors.

Reconstruction of Mini‐Hollow Polyhedron Mn2O3 Derived from MOFs as a High‐Performance Lithium Anode Material

“…After the product is further charged to 3.0 V (Figure 4f), the lattice fringes of Mn 3 O 4 , Mn 2 O 3 , and MnO 2 are observed (with the d ‐spacings of lattice fringes for MnO x (1 < x ≤ 2) summarized in Table S4 in the Supporting Information). X‐ray photoelectron spectroscopy (XPS) in Figure S8 (Supporting Information) also confirm the different oxidation states of the products at 2.0 and 3.0 V 3, 4, 5, 46. This means that the oxidation peaks at around 1.25 V should be ascribed to the oxidation of metallic Mn to Mn 3 O 4 , and the peak around 2.5 V should be the incomplete oxidation of Mn 3 O 4 to Mn 2 O 3 and MnO 2 .…”

“…Manganese oxides materials have shown great potential application as energy materials, such as water oxidation and oxygen reduction,1, 2, 3 electrochemical capacitors,4, 5 lithium–O 2 batteries,6 and lithium‐ion batteries (LIBs) 7, 8, 9, 10, 11, 12, 13, 14, 15. Owing to their high specific theoretical capacity, low cost, and environmentally benign nature, manganese oxides (MnO x , 1 ≤ x ≤ 2) are believed to be the most promising alternative anode materials for next generation LIBs 11, 13, 16, 17.…”

MnOx/carbon nanotube/reduced graphene oxide nanohybrids as high-performance supercapacitor electrodes

“…20,21 The Mn 2p spectrum of CNT/RGO/MnO x also shows two peaks at binding energies of~654 and~642 eV (Figure 3c), which can be attributed to the Mn 2p 3/2 and Mn 2p 1/2 spin-orbital doublets, respectively. 21 Moreover, the Mn 3s spectrum displays a splitting width of~5.6 eV, implying the presence of Mn 3+ and Mn 2+ states (see Supplementary Figure S8). 20 Raman spectroscopy was also used to analyze the MnO x structural features over large areas.…”

Flexible Supercapacitors – Development of Bendable Carbon Architectures

“…[136] The morphology and microstructure of the CNT/MnOx hybrid sheets varied substantially as the electrodeposition time was increased. Both the specific capacitances and rate capabilities depend on the average size of the MnOx nanoparticles on the CNTs, as indicated in CV and charge/discharge curves (Figure 10c More recently, coating MO, and/or CNT composites on textiles, sponges, and papers have also been reported as feasible methods to prepare flexible electrodes for SCs.…”