| 1. |
- Mao, Xufeng, et al.
(author)
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Polyethylene separator activated by hybrid coating improving Li+ ion transference number and ionic conductivity for Li-metal battery
- 2017
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In: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 342, s. 816-824
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Journal article (peer-reviewed)abstract
- Low Li+ ion transference number is one fatal defect of the liquid LiPF6 electrolyte for Li-metal anode based batteries. This work aims to improve Li+ ion transference number and ionic conductivity polyethylene (PE) separators. By a simple dip-coating method, the water-borne nanosized molecular sieve with 3D porous structure (ZSM-5) can be coated on PE separators. Especially, the Li+ ion transference number is greatly enhanced from 0.28 to 0.44, which should be attributed to the specific pore structure and channel environment of ZSM-5 as well as the interaction between ZSM-5 and electrolyte. Compared with the pristine PE separator, the ionic conductivity of modified separators is remarkably improved from 0.30 to 0.54 mS cm(-1). As results, the C-rate capability and cycling stability are both improved. The Li-metal battery using the ZSM-5-modified PE separator keeps 94.2% capacity after 100 cycles. In contrast, the discharge capacity retention of the battery using pristine PE is only 74.7%.
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| 2. |
- Chi, Mingming, et al.
(author)
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Excellent rate capability and cycle life of Li metal batteries with ZrO2/POSS multilayer-assembled PE separators
- 2016
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In: NANO ENERGY. - : Elsevier BV. - 2211-2855. ; 28, s. 1-11
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Journal article (peer-reviewed)abstract
- Today there are new interests in using metallic lithium as anode materials in lithium batteries because of its extremely large theoretical specific capacity. However, the low cycle efficiency and the lithium dendrite formation during repeated charge/discharge cycles hinder the practical application of metallic lithium anodes. Herein, we report a distinctive ZrO2/POSS multilayer deposited on PE separators by a simple layer-by-layer (LbL) self-assembly process to enable excellent rate capability and cycle life of lithium metal batteries. The ZrO2/POSS multilayer on PE separators weakens the solvation effect of lithium ions and significantly enhances the electrolyte uptake of separators, which is responsible for the enhanced ionic conductivity and Li+ transference number, as well as the improved Li/electrolyte interfacial stability. These advantageous characteristics of the resulting PE separators effectively decrease the electrode polarization and protect lithium metal anodes against lithium dendrites formation during repeated charge/discharge cycles, endowing LiCoO2/Li unit cells with both excellent electrochemical performance and high safety. The fundamental understanding on the effects of the micro/nano structures and properties of separators on the important electrochemistry processes at electrode/electrolyte interface of battery systems may lead to new approaches to tackle the intrinsic problems of Li metal anodes for energy storage applications.
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| 3. |
- Jin, Feng, et al.
(author)
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Enhanced rate capability and high-voltage cycling stability of single-crystal nickel-rich cathode by surface anchoring dielectric BaTiO3
- 2022
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In: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 619, s. 65-74
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Journal article (peer-reviewed)abstract
- The single-crystal Ni-rich Li(NixCoyMn1_x_y)O-2 cathode (NCM) demonstrates better cycle performance, enhanced tap density and improved mechanical structure stability, compared with polycrystalline NCM. However, limited Li+ transports, (003) plane slips and microcracks in large single particles hinder rate capability and cycle performance. To overcome these shortcomings, single-crystal NCM cathodes have been modified by nanosized tetragonal BaTiO3. Due to the dielectric properties, BaTiO(3 )particles induce electric field concentration at the BaTiO3-NCM-electrolyte interface. Thus, a large amount of lithium vacancies can be formed, providing sufficient sites for the hopping diffusion of lithium ions, thereby significantly enhancing the diffusion coefficient of Li+. Moreover, the redistribution of charges can inhibit the formation and accumulation of cathode-electrolyte-interface. Owing to the synergetic effect of BaTiO3, the BT-modified single-crystal NCM with the optimized loading shows a remarkable initial discharge capacity of 138.5 mAh g(_1) and maintains 53.8% of its initial discharge capacity after 100 cycles under 5C at 4.5 V cut-off voltage. Overall, the proposed dielectric cathode-electrolyte-interface strategy can enhance Li+ ion transport and stabilize the interface structure, leading to improved rate performance. Meanwhile, the diffusion-induced state of charge gradient can also be inhibited, resulting in high structure stability of single-crystal NCMs under high rate and cut-off voltage cycling. (C) 2022 Elsevier Inc. All rights reserved.
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| 4. |
- Kang, Yuchi, et al.
(author)
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Theoretical and numerical investigation into brush seal hysteresis without pressure differential
- 2019
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In: Advanced Composites Letters. - : SAGE PUBLICATIONS LTD. - 0963-6935 .- 2633-366X. ; 28
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Journal article (peer-reviewed)abstract
- Brush seal is a novel type contact seal, and it is well-known due to its excellent performance. However, there are many intrinsic drawbacks, such as hysteresis, which need to be solved. This article focused on modeling hysteresis in both numerical way and analytic way without pressure differential. The numerical simulation was solved by the finite element method. General contact method was used to model the inter-bristle contact, bristle-rotor contact, and bristle-backplate contact. Bristle deformation caused by both vertical and axial tip force was used to validate the numerical model together with reaction force. An analytic model in respect of the strain energy was created. The influence of structure parameters on the hysteresis ratio, with the emphasis on the derivation of hysteresis ratio formula for brush seals, was also presented. Both numerical model and analytic model presented that cant angle is the most influential factor. The aim of the article is to provide a useful theoretical and numerical method to analyze and predict the hysteresis. This work contributes the basis for future hysteresis investigation with pressure differential.
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| 5. |
- Liang, Wenbiao, et al.
(author)
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Synthesis of single-crystal LiNi0.8Co0.1Mn0.1O2 materials for Li-ion batteries by microfluidic technology
- 2023
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In: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 464
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Journal article (peer-reviewed)abstract
- Single-crystal LiNixMnyCo1-x-yO2 (SC-NMC) cathode with electro-chemo-mechanically compliant microstructure is regarded as a promising candidate for high-energy-density lithium ion battery. However, the research of Ni-rich SC-NCM still lags behind its corresponding polycrystalline cathode materials, mainly due to the difficulties in synthesis. Herein, the single-crystal LiNi0.8Mn0.1Co0.1O2 cathode (SC-NCM811) was successfully synthesized by microfluidic technology combined with the solid-state lithiation process. The nano-sized Ni0.8C- o0.1Mn0.1(OH)2 precursor prepared via microfluidic technology enhances its accessibility to lithium salts, thus exhibiting high chemical activity for lithiation reaction. As a result, the optimized SC-NCM811 cathode shows relatively small-scale grain size (<3 mu m), low cation mixing and well layered structure, which is beneficial to electrochemical kinetics and redox reversibility. The electrochemical characterization results further reveal that the optimized SC-NCM811 cathode can well balance the cycle performance and rate capability, showing good electrochemical performance. Overall, microfluidic technology is expected to provide a new strategy for pre-paring single-crystal Ni-rich cathode materials, which may extend to the commercial application of other cathode materials.
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| 6. |
- Wang, Shuai, et al.
(author)
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In Situ Synthesis of Tungsten-Doped SnO2 and Graphene Nanocomposites for High-Performance Anode Materials of Lithium-Ion Batteries
- 2017
-
In: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 9:20, s. 17163-17171
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Journal article (peer-reviewed)abstract
- The composite of tungsten-doped SnO2 and reduced graphene oxide was synthesized through a simple one pot hydrothermal method. According to the structural characterization of the composite, tungsten ions were doped in the unit cells of tin dioxide rather than simply attaching to the surface. Tungsten-doped SnO2 was in situ grown on the surface of graphene sheet to form a three-dimensional conductive network that enhanced the electron transportation and lithium-ion diffusion effectively. The issues of SnO2 agglomeration and volume expansion could be also avoided because the, tungsten-doped SnO2 nanoparticles were homogeneously distributed on a graphene sheet. As a result, the nanocomposite electrodes of tungsten-doped SnO2 and reduced graphene oxide exhibited an excellent long-term cycling performance. The residual capacity was still as high as 1100 mA h g(-1) at 0.1 A g(-1) after 100 cycles. It still remained at 776 mA h g(-1) after 2000 cycles at the current density of lA g(-1).
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| 7. |
- Wang, Yanan, et al.
(author)
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Polyethylene separators modified by ultrathin hybrid films enhancing lithium ion transport performance and Li-metal anode stability
- 2018
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In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 259, s. 386-394
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Journal article (peer-reviewed)abstract
- Poor stability of lithium metal anodes in liquid electrolytes hinders its practical application in rechargeable batteries with very high energy density. Herein, we present an approach to tackle the intrinsic problems of Li metal anodes from the standpoint of separators. By a facile and versatile method based on mussel-inspired surface chemistry, a hybrid polydopamine/octaammonium POSS (PDA/POSS) coating was spontaneously formed on the surface of PE separators through the self-polymerization and strong adhesion feature of dopamine. This ultrathin PDA/POSS coating endows PE separators with different surface characteristics while keeping its microporous structure almost unchanged. The altered surface characteristics influence the separator/electrolyte interaction, and lead to remarkable enhanced ionic conductivity (from 0.36 mS cm−1 to 0.45 mS cm−1) and Li+ ion transference number (from 0.37 to 0.47) of PE separators as well as the improved stability of lithium/electrolyte interface, which effectively decreases the electrode polarization and suppresses the lithium dendrites formation, contributing to superior C-rates capability and cycling performance of cells.
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| 8. |
- Wu, Yuan, et al.
(author)
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In situ constructed Ag/C conductive network enhancing the C-rate performance of Si based anode
- 2018
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In: Journal of Energy Storage. - : ELSEVIER SCIENCE BV. - 2352-152X .- 2352-1538. ; 17, s. 102-108
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Journal article (peer-reviewed)abstract
- Poor intrinsic electrical conductivity as well as considerable volume change during lithium alloying/dealloying process has been a critical defect for high theoretical capacity silicon-based anodes. In our work, we demonstrate the synthesis design of multiscale recombined dendritic Si/Ag/C anode for high energy density LIBs via compositing bulky silicon with uniformly distributed Ag NPs, followed by a carbon source PDA (polydopamine) coating step. Here Ag NPs are generated by an in situ redox reaction between Ag+ and PDA, no need for additional reducing agents. According to the characterization analysis, the robust porous Si/Ag/C structure can provide channels for fast Li+ diffusion and electron conduction, promoting the formation of a thinner and more stable SEI film. As a result, the Si/Ag/C composite anode still yields a relatively high residual capacity of 1422.1 mAh g (1) after 100 cycles at 0.2 A g (1). In addition, it remains 633.1 mAh g (1) after 500 cycles at a high current density of 8 A g (1).
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| 9. |
- Xu, Haiping, et al.
(author)
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Fluorine-Doped Tin Oxide Nanocrystal/Reduced Graphene Oxide Composites as Lithium Ion Battery Anode Material with High Capacity and Cycling Stability
- 2015
-
In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 7:49, s. 27486-27493
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Journal article (peer-reviewed)abstract
- Tin oxide (SnO2) is a kind of anode material with high theoretical capacity. However, the volume expansion and fast capability fading during cycling have prevented its practical application in lithium ion batteries. Herein, we report that the nanocomposite of fluorine-doped tin oxide (FTO) and reduced graphene oxide (RGO) is an ideal anode material with high capacity, high rate capability, and high stability. The FTO conductive nanocrystals were successfully anchored on RGO nanosheets from an FTO nanocrystals colloid and RGO suspension by hydrothermal treatment. As the anode material, the FTO/RGO composite showed high structural stability during the lithiation and delithiation processes. The conductive FTO nanocrystals favor the formation of stable and thin solid electrolyte interface films. Significantly, the FTO/RGO composite retains a discharge capacity as high as 1439 mAhg(-1) after 200 cycles at a current density of 100 mAg(-1). Moreover, its rate capacity displays 1148 mAhg(-1) at a current density of 1000 mAg(-1).
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| 10. |
- Xu, Wuxia, et al.
(author)
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Layer-by-Layer Deposition of Organic-Inorganic Hybrid Multilayer on Microporous Polyethylene Separator to Enhance the Electrochemical Performance of Lithium-Ion Battery
- 2015
-
In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 7:37, s. 20678-20686
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Journal article (peer-reviewed)abstract
- A simple layer-by-layer (LbL) self-assembly process of poly(acrylic acid) (PAA) and ZrO2 was applied to construct functional ultrathin multilayers on polyethylene (PE) separators without sacrificing the excellent porous structure of separators. Such PAA/ZrO2 LbL-modified PE separators possess good electrolyte wettability, excellent electrolyte uptake, high ionic conductivity and large Li+ transference number. More importantly, the top layer of LbL self-assembly would affect the dissociation of electrolyte and the formation of solid electrolyte interphase (SEI) layer in half-cells. Compared with the pristine and (PAA/ZrO2)(1)PAA-modified PE separators, (PAA/ZrO2)(3)-modified PE separator shows a larger Li+ transference number (0.6) and a faster tendency to form a stable SEI layer, endowing half-cells with excellent capacity retention at high C-rates and superior cycling performance. These fascinating characteristics will provide the LbL self-assembly with a promising method to improve the surface property of PE separators for high performance lithium-ion batteries.
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