Hongbin Wang

Rapid translocation and pharmacokinetics of hydroxylated single-walled carbon nanotubes in mice

Determining the in vivo pharmacological profiles of carbon nanotubes (CNTs) is essential for the promising biomedical applications of CNTs, such as drug delivery. Using iodine-131 tracing we studied the fundamental behavior of hydroxylated single-walled CNTs (SWNTols) shortly after they were introduced into the animal body (from 2 min to 1 h) by providing the biodistribution data and pharmacokinetic parameters. The distribution was slightly influenced by injection modes, but in any mode radioactivity was found all over the body within 2 min except brain. Liver, kidneys, stomach and lungs are the target organs with high uptake of SWNTols. The SWNTols content in several tissues, such as heart, lungs, and muscle is positively correlated with its content in the blood, showing clearly that the blood stream brings SWNTols to the whole body. This work presents the initial in vivo behavior of the water-soluble functionalized SWNTs, providing also the basic data to show opportunities and limitations for realization of the CNT-based drug vehicle.

A Metal–Organic‐Framework‐Based Electrolyte with Nanowetted Interfaces for High‐Energy‐Density Solid‐State Lithium Battery

Solid-state batteries (SSBs) are promising for safer energy storage, but their active loading and energy density have been limited by large interfacial impedance caused by the poor Li+ transport kinetics between the solid-state electrolyte and the electrode materials. To address the interfacial issue and achieve higher energy density, herein, a novel solid-like electrolyte (SLE) based on ionic-liquid-impregnated metal-organic framework nanocrystals (Li-IL@MOF) is reported, which demonstrates excellent electrochemical properties, including a high room-temperature ionic conductivity of 3.0 × 10-4 S cm-1 , an improved Li+ transference number of 0.36, and good compatibilities against both Li metal and active electrodes with low interfacial resistances. The Li-IL@MOF SLE is further integrated into a rechargeable Li|LiFePO4 SSB with an unprecedented active loading of 25 mg cm-2 , and the battery exhibits remarkable performance over a wide temperature range from -20 up to 150 °C. Besides the intrinsically high ionic conductivity of Li-IL@MOF, the unique interfacial contact between the SLE and the active electrodes owing to an interfacial wettability effect of the nanoconfined Li-IL guests, which creates an effective 3D Li+ conductive network throughout the whole battery, is considered to be the key factor for the excellent performance of the SSB.

Tuning Li-Ion Diffusion in α-LiMn1–xFexPO4 Nanocrystals by Antisite Defects and Embedded β-Phase for Advanced Li-Ion Batteries

Olivine-structured LiMn1-xFexPO4 has become a promising candidate for cathode materials owing to its higher working voltage of 4.1 V and thus larger energy density than that of LiFePO4, which has been used for electric vehicles batteries with the advantage of high safety but disadvantage of low energy density due to its lower working voltage of 3.4 V. One drawback of LiMn1-xFexPO4 electrode is its relatively low electronic and Li-ionic conductivity with Li-ion one-dimensional diffusion. Herein, olivine-structured α-LiMn0.5Fe0.5PO4 nanocrystals were synthesized with optimized Li-ion diffusion channels in LiMn1-xFexPO4 nanocrystals by inducing high concentrations of Fe2+-Li+ antisite defects, which showed impressive capacity improvements of approaching 162, 127, 73, and 55 mAh g-1 at 0.1, 10, 50, and 100 C, respectively, and a long-term cycling stability of maintaining about 74% capacity after 1000 cycles at 10 C. By using high-resolution transmission electron microscopy imaging and joint refinement of hard X-ray and neutron powder diffraction patterns, we revealed that the extraordinary high-rate performance could be achieved by suppressing the formation of electrochemically inactive phase (β-LiMn1-xFexPO4, which is first reported in this work) embedded in α-LiMn0.5Fe0.5PO4. Because of the coherent orientation relationship between β- and α-phases, the β-phase embedded would impede the Li+ diffusion along the [100] and/or [001] directions that was activated by the high density of Fe2+-Li+ antisite (4.24%) in α-phase. Thus, by optimizing concentrations of Fe2+-Li+ antisite defects and suppressing β-phase-embedded olivine structure, Li-ion diffusion properties in LiMn1-xFexPO4 nanocrystals can be tuned by generating new Li+ tunneling. These findings may provide insights into the design and generation of other advanced electrode materials with improved rate performance.

Self-Assembly of Antisite Defectless nano-LiFePO4@C/Reduced Graphene Oxide Microspheres for High-Performance Lithium-Ion Batteries

LiFePO4@C/rGO hierarchical microspheres with superior electrochemical activity and high tap density were first synthesized using a Fe-based single inorganic precursor (LiFePO4OH@RF/GO) obtained from a template-free self-assembly synthesis, following with direct calcination. The synthesis process requires no physical mixing step. The phase transformation path way from tavorite LiFePO4OH to olivine LiFePO4 upon calcination was determined by the in situ high temperature XRD technique. Benefitted from the unique structure of the material, these microspheres can be densely packed together, giving a high tap density of 1.3 g cm, and simultaneously, the defectless LiFePO4 primary nanocrystals modified with highly conductive surface carbon layer and ultrathin rGO provide good electronic and ionic kinetics for fast electron/Li ion transport. Lithium-ion batteries (LIBs), as one important technology for electric energy storage, have revolutionarily extend the battery life of portable electronic devices (e.g. smart phones, wearable devices, and laptop computers), and now stand as a promising candidate for high-power and long-life battery applications, typically for the electric transportation off the grid and the clean energy back-up and storage systems. [1-3] To date, olivine (e.g. LiFePO4), layer-type (e.g. LiNi1-x-yMnxCoyO2), and spinel (e.g. LiMn2O4) electrode materials are the three mostly used cathodes for high power LIBs. [1, 2, 4] Among them, LiFePO4 is more stable in thermodynamics and reaction kinetics than the other two owing to the presence of a robust polyanionic framework. [5-7] Moreover, LiFePO4 prevails in terms of natural abundance, cost, and environmental friendliness. The major issue to this material is the negative transport kinetics in both Li ion diffusion and electron delivery. Size tailoring, in conjunction with surface carbon (i.e. graphitic carbon, graphene, et al.) coatings to form LiFePO4/C nanocomposite is acknowledged as a technology of choice to alleviate this issue effectively. [6-9] However, when the particle size of LiFePO4/C is decreased down to nanoscale, thermodynamic instability and high risk of side reactions with the organic electrolyte become into new hazards needed to be faced with. [10] In addition, the processability and tap density (less than 1.0 g cm ) of the powders also require improvements when it comes to a practical point of view. [11] For that, small LiFePO4/C nanoparticles assembled into hierarchical architectures, ideally with a microsphere morphology, would naturally become more easily free-flowing and can be densely packed together, giving a higher tap density and hence a higher volumetric energy density. [12-14] Hydrothermal and solvothermal synthesis technologies or a combination of them are the methods commonly used to create LiFePO4/C microsphere with hierarchical architectures, the vast majority of which, however, required the use of instable and costly ferrous iron (Fe) salts as the raw material, and simultaneously a reducing agent and/or inert gas to avoid the oxidation of Fe ions during reactions. [13, 15] On top of that, most attempts to develop new routes, especially through ferric iron (Fe) based approaches, focused either on the “one-pot synthesis” or “in-situ carbon coating”, rather than considering both two concepts together. [12-14] Thus exploring a simpler synthesis scheme to produce LiFePO4/C microspheres with ideal structural features will be of great interest. In this communication, reduced GO-modified LiFePO4/C (i.e. LiFePO4@C/rGO) hierarchical microspheres were synthesized for the first time by a one-pot mixed-solvothermal process to form a ferric three-component precursor of LiFePO4OH@RF/GO, followed by direct calcination at high temperature, during which tedious physical mixing and grinding step can be totally avoided. The final LiFePO4@C/rGO microspheres created can be densely packed together, giving a high tap density of 1.3 g cm, and simultaneously, the small primary LiFePO4 nanoparticles (65 nm), in conjunction with the integrated carbonous conductive network can provide an adequate electrochemically available surface for enhancing the high-rate capability. The phase transformation mechanism from tavorite LiFePO4OH to the olivine LiFePO4 upon calcination was also determined by the in situ high temperature X-ray diffraction (XRD). [a] Dr. H. Wang, Dr. L. Liu, Prof. R. Wang, Dr. S. Jiang, L. Ni, H. Tang, Prof. Z. Zhang, Prof. S. Qiu State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, International Joint Research Laboratory of Nano-Micro Architecture Chemistry Jilin University Changchun 130012, P. R. China E-mail: zzhang@jlu.edu.cn [b] Dr. H. Wang, Dr. Z. Wang, J. Hu, Dr. H. Chen, Prof. F. Pan School of Advanced Materials Peking University Shenzhen Graduate School Shenzhen 518055, P. R. China E-mail: panfeng@pkusz.edu.cn [c] Dr. H. Qiu, Prof. Y. Wei, Prof. Z. Zhang Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education) Jilin University Changchun 130012, P. R. China [d] Dr. X. Yan School of Chemistry and Materials Science Jiangsu Normal University Xuzhou 221116, P. R. China Supporting information for this article is given via a link at the end of the document. 10.1002/cssc.201800786 A cc ep te d M an us cr ip t ChemSusChem This article is protected by copyright. All rights reserved.LiFePO4 @C/reduced graphene oxide (rGO) hierarchical microspheres with superior electrochemical activity and a high tap density were first synthesized by using a Fe3+ -based single inorganic precursor (LiFePO4 OH@RF/GO; RF=resorcinol-formaldehyde, GO=graphene oxide) obtained from a template-free self-assembly synthesis followed by direct calcination. The synthetic process requires no physical mixing step. The phase transformation pathway from tavorite LiFePO4 OH to olivine LiFePO4 upon calcination was determined by means of the inu2005situ high-temperature XRD technique. Benefitting from the unique structure of the material, these microspheres can be densely packed together, giving a high tap density of 1.3u2005gu2009cm-3 , and simultaneously, defectless LiFePO4 primary nanocrystals modified with a highly conductive surface carbon layer and ultrathin rGO provide good electronic and ionic kinetics for fast electron/Li+ ion transport.