| 11. |
- Qiu, Zhengfu, et al.
(author)
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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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In: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 472
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Journal article (peer-reviewed)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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| 12. |
- Qiu, Zhengfu, et al.
(author)
-
Surface activated polyethylene separator promoting Li+ ion transport in gel polymer electrolytes and cycling stability of Li-metal anode
- 2019
-
In: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 368, s. 321-330
-
Journal article (peer-reviewed)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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| 13. |
- 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
-
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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| 14. |
- Wang, Yanan, et al.
(author)
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Gel Polymer Electrolyte with High Li+ Transference Number Enhancing the Cycling Stability of Lithium Anodes
- 2019
-
In: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 11:5, s. 5168-5175
-
Journal article (peer-reviewed)abstract
- Lithium anodes suffer from severe safety problems in liquid electrolyte systems that result from an unstable Li plating/stripping process and Li dendrite growth, leading to rapid degradation of Li metal batteries. A polyethylene (PE)-supported gel polymer electrolyte (GPE) with excellent electrolyte uptake/retention capability was simply prepared in this paper by the construction of cross-linked polymer networks (PNs) on the surface of a poly(ethylenimine)-primed PE separator to stabilize the lithium anode. The highly delocalized negative charge of p-styrene sulfonate groups on PNs plays a role in regulating the Li+ and anion transport, giving rise to a high Li+ transference number. This GPE extended the electrochemical stability to 4.8 V and improved the stability of interface between the electrolyte and lithium metal anode (reduced overpotential and suppressed lithium dendrites) during storage and repeated lithium plating/stripping cycling. The Li metal anode-based battery employing this GPE exhibits excellent cycling stability and C-rate capability.
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| 15. |
- 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
-
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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| 16. |
- Wang, Zhuyi, et al.
(author)
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Self-Assembly of PEI/SiO2 on Polyethylene Separators for Li-Ion Batteries with Enhanced Rate Capability
- 2015
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In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 7:5, s. 3314-3322
-
Journal article (peer-reviewed)abstract
- A simple and environmentally friendly self-assembly process of oppositely charged polymer PEI and inorganic oxide SiO2 was demonstrated for the construction of an ultrathin layer on the surface of PE separator. The XPS, FT-IR, SEM, and EDS characterizations give clear evidence of the successful self-assembly of PEI and SiO2 without significantly increasing the thickness and sacrificing the pristine porous structure of PE separator. This process improves a variety of crucial properties of PE separator such as the electrolyte wetting, the electrolyte uptake, the thermal stability, the ionic conductivity, Li+ transference number, the electrochemical stability and the compatibility with lithium electrode, endowing lithium-ion battery (Li as anode and LiCoO2 as cathode) with excellent capacity retention at high C-rates and superior cycling performance. At the current density of 5 C, the cell with PE separator almost loses all the capacity. In contrast, the cell with (PEI/SiO2)-modified PE separator still holds 45.2% of the discharge capacity at 0.2 C. The stabilized SEI formation and high Li+ transference number of (PEI/SiO2)-modified PE separator were interpreted to be the substantial reasons leading to the remarkably enhanced battery performance, rendering some new insights into the role of the separator in lithium-ion batteries.
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| 17. |
- 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
-
In: Journal of Energy Storage. - : ELSEVIER SCIENCE BV. - 2352-152X .- 2352-1538. ; 17, s. 102-108
-
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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| 18. |
- 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
-
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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| 19. |
- 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
-
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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| 20. |
- Xue, Xiaoyin, et al.
(author)
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Enhanced Storage and Interface Structure Stability of NCM811 Cathodes for Lithium-Ion Batteries by Hydrophobic Fluoroalkylsilanes Modification
- 2022
-
In: ENERGY TECHNOLOGY. - : Wiley-VCH Verlagsgesellschaft. - 2194-4288 .- 2194-4296. ; 10:4
-
Journal article (peer-reviewed)abstract
- The nickel-rich ternary-layered oxide LiNixCoyMn(1-x-y)O2 (NCM) cathode exhibits high reversible capacity and low cost; however, severe capacity fade and aggravated air degradation prohibit its widespread commercialization. Herein, the hydrophobic fluoroalkylsilane-modified NCM811 cathode materials are reported. To better understand the effects of electrochemical properties of lithium-ion batteries, a variety of characterization techniques and electrochemical methods are utilized to study the surface chemistry at the cathode/electrolyte interphase. The hydrophobic fluoroalkylsilanes-grafted NCM811 cathode materials suppress the formation of residual lithium even after 30 days in humid air. The fluoroalkylsilanes layer can also provide chemical stabilization to the NCM811 cathode materials by anchoring transition metals (TM) and suppressing TM dissolution during long immersion times in electrolytes. Moreover, the degree of improvement depends on the structure of the fluoroalkylsilanes, such as the number of F groups and the length of carbon chains. As a result, FAS17-modified NCM811 cathode materials after 30-day humid air exposure (humidity 70%) exhibit the greatest overall capacity retention of 74.2% after 200 charge/discharge cycles.
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