Hongjie Tang

Accurate Control of Multishelled Co3O4 Hollow Microspheres as High-Performance Anode Materials in Lithium-Ion Batteries

More than just an empty shell: Multishelled Co3O4 microspheres were synthesized as anode materials for lithium-ion batteries in high yield and purity. As their porous hollow multishell structure guarantees a shorter Li+ diffusion length and sufficient void space to buffer the volume expansion, their rate capacity, cycling performance, and specific capacity were excellent (1615.8 mA?h?g-1 in the 30th cycle for triple-shelled Co3O4; see graph).

Growth of Polypyrrole Ultrathin Films on MoS2 Monolayers as High-Performance Supercapacitor Electrodes

A scalable solution-based approach is developed to controllably grow PPy ultrathin films on 2D MoS2 monolayers. When these sandwiched nanocomposites are utilized as supercapacitor electrodes, a record high specific capacitance, remarkable rate capability, and improved cycling stability are achieved, offering a feasible solution to create the next generation of energy-storage device with superior power density and energy density.

Three-Dimensional Graphene/Metal Oxide Nanoparticle Hybrids for High-Performance Capacitive Deionization of Saline Water

A novel and general method is proposed to construct three-dimensional graphene/metal oxide nanoparticle hybrids. For the first time, it is demonstrated that this graphene-based composite with open pore structures can be used as the high-performance capacitive deionization (CDI) electrode materials, which outperform currently reported materials. This work will offer a promising way to develop highly effective CDI electrode materials.

Molecular Architecture of Cobalt Porphyrin Multilayers on Reduced Graphene Oxide Sheets for High-Performance Oxygen Reduction Reaction†

Thanks to their lightweight, highly efficient, modular and scalable properties, polymer electrolyte membrane fuel cells (PEMFCs) have long been thought to be a promising candidate for applications in transportation and in both stationary and portable electronics. [1] Unfortunately, despite the above advantages, until now the fuel-cell technologies have failed to reach mass commercialization, and the main problems include short operational time and high cost of the materials used. [1b–d] For example, platinum-based materials are generally believed to be ideal catalysts for the oxygen reduction reaction (ORR) at the cathodes of PEMFCs; however, their disadvantages, for example, low tolerance to methanol fuel, high price and scarcity, limit the practical application of platinum-based catalysts. [2] Therefore, replacement of platinum-based materials with non-precious-metal catalysts, which are of low cost, high catalytic activity, and robust, has become one of the key issues for the realization of mass applications of PEMFCs. [3a,b]

New Insight into the Role of Gold Nanoparticles in Au@CdS Core–Shell Nanostructures for Hydrogen Evolution

A unique class of multi-channeled porous carbon nanofibers (MCPCNFs) are designed with dual-pathway ion transport capability via a modified electrospinning approach. Combined with other features including high conductivity and numerous functional groups for facilitating the formation of electric double-layer charges, the MCPCNFs exhibit excellent supercapacitive performance, holding great potential for high-performance supercapacitor electrode materials.

pH-Regulated Synthesis of Multi-Shelled Manganese Oxide Hollow Microspheres as Supercapacitor Electrodes Using Carbonaceous Microspheres as Templates

Multi‐shelled Mn2O3 hollow microspheres have been achieved through a pH‐regulated method and used as supercapacitor electrodes. The designed unique architecture allows efficient use of pseudo‐capacitive Mn2O3 nanomaterials for charge storage with facilitated transport for both ions and electrons, rendering them high specific capacitance, good rate capability, and remarkable cycling performance.

Multi-shelled LiMn2O4 hollow microspheres as superior cathode materials for lithium-ion batteries

Owing to its environmental-benignity, low-cost and abundance, spinel LiMn2O4 has long been considered as a promising cathode material for lithium-ion batteries (LIBs). However, the low electronic conductivity, small lithium diffusion coefficient and poor capacity retention hindered its further development and application. Herein, we report the synthesis of multi-shelled LiMn2O4 hollow microspheres through a hard template method, with the composition, shell number, shell thickness and porosity accurately controlled. Benefitting from the structural superiorities of multi-shelled hollow structures, the triple-shelled LiMn2O4 hollow microsphere exhibits a better cycling stability than all the reported results based on un-coated or un-doped LiMn2O4 (the capacity fading rate is 0.10% per cycle).

Multi-shelled metal oxides prepared via an anion-adsorption mechanism for lithium-ion batteries

One of the major problems in the development of lithium-ion batteries is the relatively low capacity of cathode materials compared to anode materials. Owing to its high theoretical capacity, vanadium oxide is widely considered as an attractive cathode candidate. However, the main hindrances for its application in batteries are its poor capacity retention and low rate capability. Here, we report the development of multi-shelled vanadium oxide hollow microspheres and their related electrochemical properties. In contrast to the conventional cation-adsorption process, in which the metal cations adsorb on negatively charged carbonaceous templates, our approach enables the adsorption of metal anions. We demonstrate controlled syntheses of several multi-shelled metal oxide hollow microspheres. In particular, the multi-shelled vanadium oxide hollow microspheres deliver a specific capacity of 447.9 and 402.4mAhg(-1) for the first and 100th cycle at 1,000mAg(-1), respectively. The significant performance improvement offers the potential to reduce the wide capacity gap often seen between the cathode and anode materials.

Formation of Septuple-Shelled (Co2/3Mn1/3)(Co5/6Mn1/6)2O4 Hollow Spheres as Electrode Material for Alkaline Rechargeable Battery

The multishelled (Co2/3 Mn1/3 )(Co5/6 Mn1/6 )2O4 hollow microspheres with controllable shell numbers up to septuple shells are synthesized using developed sequential templating method. Exhilaratingly, the septuple-shelled complex metal oxide hollow microsphere is synthesized for the first time by doping Mn into Co3 O4 , leading to the change of crystalline rate of precursor. Used as electrode materials for alkaline rechargeable battery, it shows a remarkable reversible capacity (236.39 mAh g-1 at a current density of 1 A g-1 by three-electrode system and 106.85 mAh g-1 at 0.5 A g-1 in alkaline battery) and excellent cycling performance due to its unique structure.

Synthesis of multi-shelled MnO2 hollow microspheres via an anion-adsorption process of hydrothermal intensification

In this study, multi-shelled manganese oxide hollow microspheres with controlled valence were successfully synthesized by varying the Mn-precursor and using an anion-adsorption process for hydrothermal intensification. Used as the supercapacitor electrode material, the multi-shelled MnO2 hollow microspheres achieved superior specific capacitance (1457 F g−1 at the discharge current density of 0.5 A g−1) and excellent cycling stability (91.2% retention of the initial capacitance after 4000 cycles), benefiting from the superiorities of these unique hierarchical structures such as increased active sites, shortened ion and electron transport lengths, better contact between the electrolyte and active materials, as well as better protection of interior shells by the exterior shell.