Li-Ion Storage Performance of MnO Nanoparticles Coated with Nitrogen-Doped Carbon Derived from Different Carbon Sources

Triple Layer Tungsten Trioxide, Graphene, and Polyaniline Composite Films for Combined Energy Storage and Electrochromic Applications

Different polyaniline (PANI)-based hybrid films were successfully prepared by electro-polymerizing aniline monomers onto pre-spin-coated indium tin oxide (ITO) glass slides with WO₃, graphene, or WO₃/graphene films. Comparing with pristine PANI, the shifts of the characteristic peaks of PANI-based nanocomposites in UV-visible absorption spectra (UV-vis) and Fourier transform infrared spectroscopy (FT-IR) indicate the chemical interaction between the PANI matrix and the nanofillers, which is also confirmed by the scanning electron microscope (SEM) images. Corresponding coloration efficiencies were obtained for the WO₃/PANI (40.42 cm² C^-1), graphene/PANI (78.64 cm² C^-1), and WO₃/graphene/PANI (67.47 cm² C^-1) films, higher than that of the pristine PANI film (29.4 cm² C^-1), suggesting positive effects of the introduced nanofillers on the electrochromic performance. The areal capacitances of the films were observed to increase following the order as bare WO₃ < WO₃/graphene < pristine PANI < WO₃/PANI < graphene/PANI < WO₃/graphene/PANI films from both the cyclic voltammogram (CV) and galvanostatic charge-discharge (GCD) results. The enhanced energy storage and electrochromic performances of the PANI-based nanocomposite films can be attributed to the capacitance contributions of the introduced nanofillers, increased PANI amount, and the rougher morphology due to the embedment of the nanofillers into the PANI matrix. This extraordinary energy storage and electrochromic performances of the WO₃/graphene/PANI film make it a promising candidate for combined electrochromic and energy storage applications.

Effect of the Pillar Size on the Electrochemical Performance of Laser-Induced Silicon Micropillars as Anodes for Lithium-Ion Batteries

Silicon micropillars with tunable sizes are successfully fabricated on copper foils by using nanosecond-pulsed laser irradiation and then used as anodes for lithium-ion batteries. The size of the silicon micropillars is manipulated by using different slurry layer thicknesses ranging from a few microns to tens of microns. The effects of the pillar size on electrochemical properties are thoroughly investigated. The smaller the pillars, the better the electrochemical performance. A capacity of 1647 mAh g−1 at 0.1 C current rate is achieved in the anode with the smallest pillars, with 1215, 892, and 582 mAh g−1 at 0.2, 0.5, and 1.0 C, respectively. Although a significant difference in discharge capacity is observed in the early period of cycling among micropillars of different sizes, this discrepancy becomes smaller as a function of the cycle number. Morphological studies reveal that the expansion of micropillars occurred during long-term cycling, which finally led to the formation of island-like structures. Also, the formation of a solid electrolyte interphase film obstructs Li+ diffusion into Si for lithiation, resulting in capacity decay. This study demonstrates the importance of minimizing the pillar size and optimizing the pillar density during anode fabrication.

Mixed-valent MnSiO3/C nanocomposite for high-performance asymmetric supercapacitor

In this work, carbon-coated manganese silicate (MnSiO₃/C) nanocomposite with excellent cycling stability was fabricated via a cost-effective process. The carbon coating followed with a CO₂ heat treatment process on the manganese silicate results in mixed-valent hierarchically-porous nanoparticles, which tightly connects with an ultrathin (∼1.5 nm) and ordered carbon coating layer. This composite features rectangular-like cyclic voltammetry curve with two couples of redox peaks, suppressing the irreversible reactions and thus providing a broad and stable working voltage. By fitting the CV curves, the MnSiO₃/C demonstrates a capacitive energy-storage behavior. The as-assembled activated carbon//MnSiO₃/C asymmetric supercapacitor in 1 M Na₂SO₄ aqueous electrolyte is found to have excellent cycling stability, with 95.5% retention of initial after 10,000 cycles. This device could deliver 25.8 W h kg^-1 energy density at the power density of 1 kW kg^-1 with ∼10 mg cm^-2 high mass loading, suggesting a bright prospect in practical application.

Recent Progress of Electrochemical Energy Devices: Metal Oxide–Carbon Nanocomposites as Materials for Next-Generation Chemical Storage for Renewable Energy

With the importance of sustainable energy, resources, and environmental issues, interest in metal oxides increased significantly during the past several years owing to their high theoretical capacity and promising use as electrode materials for electrochemical energy devices. However, the low electrical conductivity of metal oxides and their structural instability during cycling can degrade the battery performance. To solve this problem, studies on carbon/metal-oxide composites were carried out. In this review, we comprehensively discuss the characteristics (chemical, physical, electrical, and structural properties) of such composites by categorizing the structure of carbon in different dimensions and discuss their application toward electrochemical energy devices. In particular, one-, two-, and three-dimensional (1D, 2D, and 3D) carbon bring about numerous advantages to a carbon/metal-oxide composite owing to the unique characteristics of each dimension.

3D Hierarchical Microballs Constructed by Intertwined MnO@N-doped Carbon Nanofibers towards Superior Lithium-Storage Properties

MnO is a promising high-capacity anode material for lithium-ion batteries (LIBs), but pristine material suffers short cycle life and poor rate capability, thus hindering the practical application. In this work, a new type of porous MnO microballs stringed with N-doped porous carbon (3DHB-MnO@NC) with a well-connected hierarchical three-dimensional network structure was prepared by the facile self-template method. The 3DHB-MnO@NC electrode can effectively promote the ion/electron transfer and buffer the large volume change of electrode during the electrochemical reaction. As the anode for LIBs, the 3DHB-MnO@NC possesses outstanding cycling performance (1247.7 mA h g^-1 after 90 cycles at 200 mA g^-1 ) and good rate capabilities (949.6 mA h g^-1 after 450 cycles at 1000 mA g^-1 ). The facile self-template method of the prepared 3DHB-MnO@NC composite paves a new way for practical applications of MnO in high performance LIBs.

Effect of cobalt alloying on the electrochemical performance of manganese oxide nanoparticles nucleated on multiwalled carbon nanotubes

MnO is an electrically insulating material which limits its usefulness in lithium ion batteries. We demonstrate that the electrochemical performance of MnO can be greatly improved by using oxygen-functional groups created on the outer walls of multiwalled carbon nanotubes (MWCNTs) as nucleation sites for metal oxide nanoparticles. Based on the mass of the active material used in the preparation of electrodes, the composite conversion-reaction anode material Mn_1-x Co _x O/MWCNT with x = 0.2 exhibited the highest reversible specific capacity, 790 and 553 mAhg^-1 at current densities of 40 and 1600 mAg^-1, respectively. This is 3.1 times higher than that of MnO/MWCNT at a charge rate of 1600 mAg^-1. Phase segregation in the [Formula: see text] nanoparticles was not observed for x ≤ 0.15. Capacity retention in x = 0, 0.2, and 1 electrodes showed that the corresponding specific capacities were stabilized at 478, 709 and 602 mAhg^-1 respectively, after 55 cycles at a current density of 400 mAg^-1. As both MnO and CoO exhibit similar theoretical capacities and MnO/MWCNT and CoO/MWCNT anodes both exhibit lower performance than Mn_0.8Co_0.2O/MWCNT, the improved performance of the [Formula: see text] alloy likely arises from beneficial synergistic interactions in the bimetallic system.

Conversion Reaction-Based Oxide Nanomaterials for Lithium Ion Battery Anodes

Developing high-energy-density electrodes for lithium ion batteries (LIBs) is of primary importance to meet the challenges in electronics and automobile industries in the near future. Conversion reaction-based transition metal oxides are attractive candidates for LIB anodes because of their high theoretical capacities. This review summarizes recent advances on the development of nanostructured transition metal oxides for use in lithium ion battery anodes based on conversion reactions. The oxide materials covered in this review include oxides of iron, manganese, cobalt, copper, nickel, molybdenum, zinc, ruthenium, chromium, and tungsten, and mixed metal oxides. Various kinds of nanostructured materials including nanowires, nanosheets, hollow structures, porous structures, and oxide/carbon nanocomposites are discussed in terms of their LIB anode applications.

MnO nanocrystals incorporated in a N-containing carbon matrix for Li ion battery anodes

In this study, MnO nanocrystals incorporated in a N-containing carbon matrix were fabricated by the facile thermal decomposition of manganese nitrate-glycine gels.

Facile synthesis of MnOx nanoparticles sandwiched between nitrogen-doped carbon plates for lithium ion batteries with stable capacity and high-rate capability

MnO_x nanoparticles sandwiched between nitrogen-doped carbon plates architecture (C/MnO_x/C) has been successfully synthesized via a step-by-step strategy.

Nitrogen-doped carbon-coated Ti–Fe–O nanocomposites with enhanced reversible capacity and rate capability for high-performance lithium-ion batteries

An N-doped carbon-coated Ti–Fe–O multicomponent nanocomposite with a moderate Ti/Fe molar ratio of 1 : 2 exhibits good cycling performance as well as outstanding rate capability.

Ti–Sn–O composite oxides coated with N-doped carbon exhibiting enhanced lithium storage performance

The long-term cycling performance of S1-400C1 and TiO₂-400C1 at different rates.

Enhanced electrochemical performances of MoO2 nanoparticles composited with carbon nanotubes for lithium-ion battery anodes

Lab-made CNT nanocomposites decorated with MoO₂ nanoparticles (MoO₂/CNTs) demonstrated superior cycling and rate performances as LIB anode materials.