| 1. |
- Jin, Rui, et al.
(författare)
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High Li+ Ionic Flux Separator Enhancing Cycling Stability of Lithium Metal Anode
- 2018
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Ingår i: ACS Sustainable Chemistry and Engineering. - : AMER CHEMICAL SOC. - 2168-0485. ; 6:3, s. 2961-2968
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Tidskriftsartikel (refereegranskat)abstract
- The metallic lithium anode provides unparalleled opportunities for rechargeable batteries with very high energy density. A main problem hindering the development of cells using metallic lithium anodes stems from the electrochemical instability of the interface between metallic lithium and organic liquid electrolytes. This paper reports an approach rationally designing the surface characteristic of separator for stable, dendrite-free operation of lithium-metal batteries. A unique polymer multilayer PEI(PAA/PEO)(3) was fabricated on the microporous polyethylene (PE) separator by a simple layer-by-layer (LbL) assembly process, which maintains the pore structure and thickness of PE separator but remarkably enhances the ionic conductivity (from 0.36 mS cm(-1) to 0.45 mS cm(-1)) and Li+ transference number (from 0.37 to 0.48), as well as stabilizes lithium metal anodes against the reaction with liquid electrolytes during storage and repeated charge/discharge cycles, which is responsible for restraining the electrode polarization and the formation of lithium dendrites, and therefore endows lithium metal batteries with long-term cycling at high columbic efficiency and excellent rate capability, as well as the improved safety.
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| 2. |
- Mao, Xufeng, et al.
(författare)
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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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Ingår i: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 342, s. 816-824
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Qiu, Zhengfu, et al.
(författare)
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Construction of silica-oxygen-borate hybrid networks on Al2O3-coated polyethylene separators realizing multifunction for high-performance lithium ion batteries
- 2020
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 472
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Tidskriftsartikel (refereegranskat)abstract
- The separator, an essential component in lithium ion batteries, faces more challenges with the increasing diversification of electrode materials towards higher energy density and longer life. Herein we report the performance improvements of lithium ion batteries enabled by the multifunctional separator, which is fabricated by constructing the silica-oxygen-borate (Si-O-B) thin layer on Al2O3-coated polyethylene separators through surface engineering. This separator inherits the advantage of Al2O3-coated polyethylene separators in terms of excellent thermal stability and puncture strength, and no obvious dimensional change at 200 degrees C. The Si-O-B thin layer provides abundant Lewis acid sites and excellent electrolyte uptake to desolvate Li+ ions and traps anions, and therefore favors excellent lithium ion transport properties and lithium/electrolyte interfacial stability. More importantly, the Si-O-B hybrid thin layer endows an additional function of scavenging HF and H2O molecules. The benefits offered by this separator are demonstrated by the enhanced C-rates capability and cycling performance of both LiCoO2/Li half-cell and NCM/graphite full cell, which lies far beyond those achievable with commercial polyethylene separators and Al2O3-coated polyethylene separators. This work presents a simple and efficient strategy to construct multifunctional separators with excellent comprehensive properties, and provides inspiration for the rational design of advanced separators towards next-generation high-performance batteries.
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| 4. |
- Qiu, Zhengfu, et al.
(författare)
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Surface activated polyethylene separator promoting Li+ ion transport in gel polymer electrolytes and cycling stability of Li-metal anode
- 2019
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 368, s. 321-330
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a strategy to fabricate surface activated polyethylene (PE)-supported gel polymer electrolyte (GPE) with high ion transport ability, excellent electrolyte retention and mechanical properties to stabilize lithium (Li)-metal anodes. The inert outer and inner pore surface activation of polyethylene is demonstrated by coating an ultrathin zirconium oxide nanocrystal (ZrO2)/polyhedral oligomeric silsesquioxane (POSS) composite layer through a simple layer by layer (LBL) assembly method prior to the in situ polymerization. It is found that the activation layer may improve the Li+ ion transference number and induce the formation of GPE with a gradient structure by the interaction with the initiator system, giving rise to higher ion transport ability of final GPE. On the other hand, the GPE using the activated PE separator as support improves the Li/electrolyte interfacial stability during storage and repeated lithium plating/stripping cycling. A stable voltage profile with cycling for more than 800 h in a Li/Li symmetric cell was obtained by using surface activated PE-supported GPE. When it is assembled into the cells with metallic lithium anodes and lithium cobalt oxide (LiCoO2) cathodes, the cells show excellent rate capability and cycling performance, as well as effective dendrite inhibition.
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| 5. |
- Wang, Yanan, et al.
(författare)
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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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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 259, s. 386-394
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Tidskriftsartikel (refereegranskat)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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