Hongtao Guo

Bio: Hongtao Guo is an academic researcher from Nanjing Forestry University. The author has contributed to research in topics: Materials science & Electromagnetic shielding. The author has an hindex of 2, co-authored 6 publications receiving 36 citations.

Electrospun fibrous materials and their applications for electromagnetic interference shielding: A review

Abstract: Owing to the development of electronic information technology, the pollution of electromagnetic wave (EMW) radiation is getting worse. Thus, it is urgent to investigate shielding materials with excellent electromagnetic interference (EMI) shielding properties. Recently, electrospinning has been developed in various fields, and one-dimensional nanofibers prepared by electrospinning can realize the shielding of EMW, due to their outstanding advantages. In this review, at the beginning, the basic mechanism of electrospinning technology and related EMI shielding are introduced. Then, different fibrous materials directly from electrospinning for the EMI shielding are summarized. Next, electrospun EMI shielding composites by different post treatments are discussed. Finally, various influencing factors on the EMI shielding properties are summarized. At the end, conclusions and future perspectives are provided. Hopefully, this review would provide basic understanding on the development of electrospun fibrous materials for EMI shielding, and give the future roadmap for the high performance electrospun fiber-based EMI shields.

Wood-Derived High-Mass-Loading MnO2 Composite Carbon Electrode Enabling High Energy Density and High-Rate Supercapacitor.

Abstract: The simple design of a high-energy-density device with high-mass-loading electrode has attracted much attention but is challenging. Manganese oxide (MnO2 ) with its low cost and excellent electrochemical performance shows high potential for practical application in this regard. Hence, the high-mass-loading of the MnO2 electrode with wood-derived carbon (WC) as the current collector is reported through a convenient hydrothermal reaction for high-energy-density devices. Benefiting from the high-mass-loading of the MnO2 electrode (WC@MnO2 -20, ≈14.1 mg cm-2 ) and abundant active sites on the surface of the WC hierarchically porous structure, the WC@MnO2 -20 electrode shows remarkable high-rate performance of areal/specific capacitance ≈1.56 F cm-2 /45 F g-1 , compared to the WC electrode even at the high density of 20 mA cm-2 . Furthermore, the obtained symmetric supercapacitor exhibits high areal/specific capacitances of 3.62 F cm-2 and 87 F g-1 at 1.0 mA cm-2 and high energy densities of 0.502 mWh cm-2 /12.2 Wh kg-1 with capacitance retention of 75.2% after 10 000 long-term cycles at 20 mA cm-2 . This result sheds light on a feasible design strategy for high-energy-density supercapacitors with the appropriate mass loading of active materials and low-tortuosity structural design while also encouraging further investigation into electrochemical storage.

Microstructures and electrochemical performances of TiO2-coated Mg–Zr co-doped NCM as a cathode material for lithium-ion batteries with high power and long circular life

Abstract: To enhance the electrochemical properties of LiNi1/3Co1/3Mn1/3O2 (NCM) materials for lithium-ion batteries (LIBs), TiO2-coated Mg–Zr co-doped NCM cathode materials (MZT-NCM) were fabricated via a two-step solid-state method using Mg(OH)2, Zr(OH)4 and Ti(OH)3 as Mg, Zr and Ti sources, respectively. The electrochemical characteristics were assessed by the hybrid pulse power characteristic (HPPC) test, galvanostatic charge–discharge, EIS and CV test. Compared with NCM, the electrochemical properties of MZT-NCM as a cathode material in a pouch-cell were enhanced, especially high power performance and the stability of long cycle life. The MZT-NCM exhibits an excellent power performance of 2051 W, compared to that of the NCM, which only achieves 1736 W at 50% state of charge (SOC). Furthermore, the MZT-NCM samples deliver an outstanding capacity retention rate of 91.10% after 7000 cycles at 3C, which is nearly 10% higher than that of NCM. The modification strategy has a positive effect on the electrochemical characteristics of NCM cathode materials, which is expected to provide meaningful guidance for developing high power and long cycle life LIBs.

Multifunctional Flame-Retardant Melamine-Based Hybrid Foam for Infrared Stealth, Thermal Insulation, and Electromagnetic Interference Shielding.

Abstract: Multifunctionalization is an important development direction of electromagnetic interference (EMI)-shielding materials. However, it is still a huge challenge to effectively integrate multiple functions into materials. Herein, we reported a facile method to fabricate multifunctional EMI-shielding materials, which were assembled with multidimensional components consisting of a 3D melamine-formaldehyde (MF) foam skeleton, 0D ferroferric oxide (Fe3O4) nanoparticles, and 1D silver nanowires (AgNWs) via coprecipitation and dip-coating processes. Due to the coaction of conductive AgNWs and magnetic Fe3O4 nanoparticles, the resultant hybrid foam showed excellent absorption-dominant EMI-shielding performances with a high specific EMI-shielding effectiveness value of 12,704 dB cm2 g-1. Moreover, thanks to the multilayer porous micro-/nanostructure and the nonflammability of functional coatings, the hybrid foam shows excellent flame retardancy and heat insulation, making it attractive for the functions of infrared stealth and heat insulation. The corresponding mechanism is discussed in detail. Combined with the advantages of high thermal insulation, flame retardancy, elasticity, and excellent absorption-dominant EMI-shielding performances, the hybrid foam showed great applications in the fields of both military and civilian. This work provides new inspiration and insights for the design of multifunctional high-performance EMI-absorbing materials.

Two-Dimensional Core-Shell Structure of Cobalt-Doped@MnO2 Nanosheets Grown on Nickel Foam as a Binder-Free Battery-Type Electrode for Supercapacitor Application

Abstract: Herein, we present an interfacial engineering strategy to construct an efficient hydrothermal approach by in situ growing cobalt-doped@MnO2 nanocomposite on highly conductive nickel foam (Ni foam) for supercapacitors (SCs). The remarkably high specific surface area of Co dopant provides a larger contacting area for MnO2. In the meantime, the excellent retentions of the hierarchical phase-based pore architecture of the cobalt-doped surface could beneficially condense the electron transportation pathways. In addition, the nickel foam (Ni foam) nanosheets provide charge-transport channels that lead to the outstanding improved electrochemical activities of cobalt-doped@MnO2. The unique cobalt-doped@MnO2 nanocomposite electrode facilitates stable electrochemical architecture, multi-active electrochemical sites, and rapid electro-transports channels; which act as a key factor in enhancing the specific capacitances, stability, and rate capacities. As a result, the cobalt-doped@MnO2 nanocomposite electrode delivered superior electrochemical activities with a specific capacitance of 337.8 F g–1 at 0.5 A g–1; this is greater than pristine MnO2 (277.9 F g–1). The results demonstrate a worthy approach for the designing of high-performance SCs by the grouping of the nanostructured dopant material and metal oxides.