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Xu W.,Pacific Northwest National Laboratory | Wang J.,Pacific Northwest National Laboratory | Wang J.,Shanghai JiaoTong University | Ding F.,Tianjin Institute of Power Sources | And 5 more authors.
Energy and Environmental Science | Year: 2014

Lithium (Li) metal is an ideal anode material for rechargeable batteries due to its extremely high theoretical specific capacity (3860 mA h g -1), low density (0.59 g cm-3) and the lowest negative electrochemical potential (-3.040 V vs. the standard hydrogen electrode). Unfortunately, uncontrollable dendritic Li growth and limited Coulombic efficiency during Li deposition/stripping inherent in these batteries have prevented their practical applications over the past 40 years. With the emergence of post-Li-ion batteries, safe and efficient operation of Li metal anodes has become an enabling technology which may determine the fate of several promising candidates for the next generation energy storage systems, including rechargeable Li-air batteries, Li-S batteries, and Li metal batteries which utilize intercalation compounds as cathodes. In this paper, various factors that affect the morphology and Coulombic efficiency of Li metal anodes have been analyzed. Technologies utilized to characterize the morphology of Li deposition and the results obtained by modelling of Li dendrite growth have also been reviewed. Finally, recent development and urgent need in this field are discussed. © The Royal Society of Chemistry.

Shao Y.,Pacific Northwest National Laboratory | Ding F.,Pacific Northwest National Laboratory | Ding F.,Tianjin Institute of Power Sources | Xiao J.,Pacific Northwest National Laboratory | And 7 more authors.
Advanced Functional Materials | Year: 2013

A Li-air battery could potentially provide three to five times higher energy density/specific energy than conventional batteries and, thus, enable the driving range of an electric vehicle to be comparable to gasoline vehicles. However, making Li-air batteries rechargeable presents significant challenges, mostly related to the materials. Here, the key factors that influence the rechargeability of Li-air batteries are discussed with a focus on nonaqueous systems. The status and materials challenges for nonaqueous rechargeable Li-air batteries are reviewed. These include electrolytes, cathode (electrocatalysts), lithium metal anodes, and oxygen-selective membranes (oxygen supply from air). A perspective for the future of rechargeable Li-air batteries is provided. Rechargeable lithium-air batteries could potentially provide an energy storage capacity of three to five times that of current Li-ion batteries. However, significant material challenges exist for each of its components, among which are electrolytes, cathodes/catalysts, anodes, and oxygen-selective membranes for oxygen supply. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ding F.,Pacific Northwest National Laboratory | Xu W.,Pacific Northwest National Laboratory | Graff G.L.,Pacific Northwest National Laboratory | Zhang J.,Pacific Northwest National Laboratory | And 11 more authors.
Journal of the American Chemical Society | Year: 2013

Rechargeable lithium metal batteries are considered the "Holy Grail" of energy storage systems. Unfortunately, uncontrollable dendritic lithium growth inherent in these batteries (upon repeated charge/discharge cycling) has prevented their practical application over the past 40 years. We show a novel mechanism that can fundamentally alter dendrite formation. At low concentrations, selected cations (such as cesium or rubidium ions) exhibit an effective reduction potential below the standard reduction potential of lithium ions. During lithium deposition, these additive cations form a positively charged electrostatic shield around the initial growth tip of the protuberances without reduction and deposition of the additives. This forces further deposition of lithium to adjacent regions of the anode and eliminates dendrite formation in lithium metal batteries. This strategy may also prevent dendrite growth in lithium-ion batteries as well as other metal batteries and transform the surface uniformity of coatings deposited in many general electrodeposition processes. © 2013 American Chemical Society.

Chen X.,Pacific Northwest National Laboratory | Li X.,Pacific Northwest National Laboratory | Ding F.,Pacific Northwest National Laboratory | Ding F.,Tianjin Institute of Power Sources | And 8 more authors.
Nano Letters | Year: 2012

A cost-effective and scalable method is developed to prepare a core-shell structured Si/B 4C composite with graphite coating with high efficiency, exceptional rate performance, and long-term stability. In this material, conductive B 4C with a high Mohs hardness serves not only as micro/nano-millers in the ball-milling process to break down micron-sized Si but also as the conductive rigid skeleton to support the in situ formed sub-10 nm Si particles to alleviate the volume expansion during charge/discharge. The Si/B 4C composite is coated with a few graphitic layers to further improve the conductivity and stability of the composite. The Si/B 4C/graphite (SBG) composite anode shows excellent cyclability with a specific capacity of ∼822 mAhg -1 (based on the weight of the entire electrode, including binder and conductive carbon) and ∼94% capacity retention over 100 cycles at 0.3 C rate. This new structure has the potential to provide adequate storage capacity and stability for practical applications and a good opportunity for large-scale manufacturing using commercially available materials and technologies. © 2012 American Chemical Society.

Han Z.,Wuhan University | Yu J.,Tianjin Institute of Power Sources | Zhan H.,Wuhan University | Liu X.,Tianjin Institute of Power Sources | Zhou Y.,Wuhan University
Journal of Power Sources | Year: 2014

The layered LiMO2 (M = Ni, Co and Mn) materials LiNi 1/3Co1/3Mn1/3O2 and LiNi 0.4Co0.2Mn0.4O2 are synthesized by rheological phase method. Sb2O3-modified phases are further obtained by mechanical ball milling treatment. The structure and morphology of the bare and modified samples are characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Charge/discharge tests indicate that the modified phases all improve cycling stability, rate capability and thermal safety. Careful comparison of the charge/discharge profiles reveals that the serious polarization increment in cycling is suppressed in the Sb2O3-modified LiMO 2 electrodes. AC impedance shows that Sb2O 3/LiNi1/3Co1/3Mn1/3O2 electrode has smaller Rct and Rf value. Further analysis proves that Sb2O3 hinders the reaction between electrolyte and cathode during charge/discharge process and helps to stabilize the SEI. Other experiments prove that using Sb2O3-coated separator can achieve similar positive effect on layered LiMO2 cathode. © 2013 Elsevier B.V. All rights reserved.

Zong J.,Tianjin University | Peng Q.,Tianjin Institute of Power Sources | Yu J.,Tianjin Institute of Power Sources | Liu X.,Tianjin University | Liu X.,Tianjin Institute of Power Sources
Journal of Power Sources | Year: 2013

A brand new method for synthesizing Mn(PO3(OH))·3H 2O is attained in this paper. During this process, pure flake-like Mn(PO3(OH))·3H2O precipitate is prepared using C2H5OH as initiator. Besides that, LiMn 0.5Fe0.5PO4/C is successfully synthesized from the Mn(PO3(OH))·3H2O precursor at 650°C for the first time. Thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) are applied in the characterization of the Mn(PO3(OH))·3H2O precursor and LiMn 0.5Fe0.5PO4/C. High-resolution transmission electron microscopy (HRTEM) is also used to investigate the morphology of LiMn0.5Fe0.5PO4/C. X-ray photoelectron spectroscopy (XPS) and galvanostatic charge and discharge test are employed to characterize the Mn(PO3(OH))·3H2O precursor and LiMn0.5Fe0.5PO4 material, respectively. The as-prepared LiMn0.5Fe0.5PO4/C material exhibited a reversible capacity of 131 mAh g-1 at 0.05 C. It can be confirmed that the incorporation of Fe into LiMnPO4 can significantly improve the electrochemical properties for improving the conductivity of the material and facilitating the Li+ diffusion. In addition, a capacity of 120 mAh g-1 is still delivered at 0.05 C rate with a capacity retention of about 91% after 25 cycles, and reversible capacity can reach 105 mAh g-1 at 1 C. © 2012 Published by Elsevier B.V. All rights reserved.

Qie F.,Tianjin University | Qie F.,Tianjin Institute of Power Sources | Tang Z.,Tianjin University
Materials Express | Year: 2014

In this paper, Cu-doped Li2Zn1-xCuxTi3O8 (x = 0, 0.05, 0.1, 0.15) were successfully prepared using titanate nanowires as a precursor. The effects of Cu-doping on the physicochemical properties of Li2ZnTi3O8 were extensively investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), galvanostatic charge-discharge testing, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that the Li2Zn1-xCuxTi3O8 (x = 0, 0.05, 0.1, 0.15) compounds are pure well-crystallized spinel phase. In addition, the Cu-doping does not change the morphology and the electrochemical reaction process of Li2ZnTi3O8. Galvanostatic charge-discharge testing denotes that the Li2Zn0.9Cu0.1Ti3O8 exhibits highest discharge capacity among all the samples and show higher cyclic stability and better rate capability compared with pristine Li2ZnTi3O8. When charge-discharge current density increases up to 1000 mA g-1, the Li2Zn0.9Cu0.1Ti3O8 sample still maintains a capacity of 165.4 mA h g-1, while the pristine Li2ZnTi3O8 sample shows severe capacity decline at same current density. CV result reveals that the Li2Zn0.9Cu0.1Ti3O8 has the lowest polarization. It is shown by EIS that the Li2Zn0.9Cu0.1Ti3O8 exhibits higher diffusion coefficient of Li+. The superior cycling performance and good rate capability, as well as simple synthesis route of the Cu-doped Li2ZnTi3O8 are expected to show a potential commercial application. © 2014 by American Scientific Publishers. All rights reserved.

Lu Z.,Tianjin Institute of Power Sources | Zhang L.,Tianjin Institute of Power Sources | Liu X.,Tianjin Institute of Power Sources
Journal of Power Sources | Year: 2010

Si-SiO2-C composites are synthesized by ball milling the mixture of SiO, graphite and coal pitch, and subsequent heat treatment at 900 °C in inert atmosphere. The electrochemical performance and microstructure of the composites are investigated. XRD and TEM tests indicate that the carbon-coating structure of Si-SiO2-C composites form in pyrolysis process, which can remarkably improve the electrochemical cycling performance. The coal pitch as carbon precursor and graphite demonstrate the same important effect on the Li-alloying/de-alloying property of the Si-SiO2-C composites. The Si-SiO2-C composites exhibit the electrochemical reversible Li-alloying/de-alloying capacity of 700 mAh g-1 and excellent cyclic stability even at about the 90th cycle. © 2010 Elsevier B.V. All rights reserved.

Chong J.,Lawrence Berkeley National Laboratory | Chong J.,Tianjin Institute of Power Sources | Xun S.,Lawrence Berkeley National Laboratory | Song X.,Lawrence Berkeley National Laboratory | And 2 more authors.
Nano Energy | Year: 2013

Li4P2O7-stabilized LiNi0.5Mn1.5O4 was prepared by solid-state synthesis. The material was characterized by X-ray diffraction and high-resolution transition electron microscopy, which showed a coating layer (<10nm) of Li4P2O7 crystallite co-existing with a little Li3PO4 on the LiNi0.5Mn1.5O4/Li4P2O7 primary particles. LiNi0.5Mn1.5O4/Li4P2O7 synthesized at 760°C for 200h had a cubic spinel structure with a space group of Fd3- m; its estimated crystallite size was 527nm. LiNi0.5Mn1.5O4/Li4P2O7 possessed better rate capability and cycling capability. The introduced Li4P2O7 coating layer acted as a solid electrolyte or artificial SEI layer: by separating the active material from the electrolyte, the coating layer prevented the Ni2+/Ni3+ or Ni3+/Ni4+ redox couple from decomposing the electrolyte. Stress/strain from the Ni2+⇌Ni3⇌Ni4+ spinel phase change caused fractures and pulverization of the cycled stoichiometric LiNi0.5Mn1.5O4 crystal surface, especially noticeable for this well-developed micro-sized crystal. The ordered stoichiometric LiNi0.5Mn1.5O4 had more side reactions, led to a quick fading of the material's capacity. Both the Li4P2O7 coating layer and the disordered Fd3- m space group LiNi0.5Mn1.5O4 structure bring benefit to the LiNi0.5Mn1.5O4/Li4P2O7 performance. Thus, the introduced Li4P2O7 coating layer can build an effective solid electrolyte or artificial SEI layer to protect the interface between LiNi0.5Mn1.5O4 and electrolyte. © 2012 Elsevier Ltd.

Xun S.,Lawrence Berkeley National Laboratory | Chong J.,Lawrence Berkeley National Laboratory | Chong J.,Tianjin Institute of Power Sources | Song X.,Lawrence Berkeley National Laboratory | And 2 more authors.
Journal of Materials Chemistry | Year: 2012

Li 3V 2(PO 4) 3 was prepared from a stoichiometric and a non-stoichiometric set of precursors. The non-stoichiometric preparation led to particles coated with a thin layer (<5 nm) of Li 4P 2O 7 and Li 3PO 4 (G-LVPO), as verified through high resolution transmission electron microscopy and slow scan X-ray diffraction. The stoichiometric material was bare (B-LVPO), i.e. no film was present, as confirmed by the same techniques. Amorphous and crystalline Li 3V 2(PO 4) 3 will co-exist when the synthesis temperature ranges from 700 °C to below 900 °C. The Li 3V 2(PO 4) 3 phase will completely crystallize and particles grow bigger than 300 nm when the synthesis temperature reaches to or higher than 900 °C. Cyclic voltammetry plots of B-LVPO and G-LVPO show that they undergo the same phase transitions between 3.0 V and 4.3 V and preserve a good structural stability over cycled in the range from 3.0 V to 4.8 V. G-LVPO has a smaller ohmic/charge transfer resistance compared with B-LVPO, which enables a better rate capability and cycling ability of G-LVPO than B-LVPO. In this report we were able to determine that the non-stoichiometric chemistry leads to a coating of Li 4P 2O 7 and Li 3PO 4 on the Li 3V 2(PO 4) 3 and that the coating appears to improve the rate capability and the cycling ability of the material. © 2012 The Royal Society of Chemistry.

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