Manufacture and Surface Modification of Polyolefin Separator

Xue, Zheng; Zhang, Zhengcheng; Zhang, Sheng S.

doi:10.1007/978-3-319-15458-9_12

Cited by 6 publications

(6 citation statements)

References 23 publications

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“…Porous membrane separators, such as polyethylene (PE), polypropylene (PP) and polypropylene-polyethylene-polypropylene (PP/PE/PP) made of polyolefin, are widely used in the lithium-ion batteries for EVs 11 12 13 . They can be manufactured by cold and hot stretch of precursor films with different stretch rates and ratios, followed by annealing until achieving a required porosity 12 14 15 16 17 18 . The mechanical properties of separators are highly dependent not only on the material that they are made of but also on their manufacturing processes.…”

mentioning

confidence: 99%

Li-ion Battery Separators, Mechanical Integrity and Failure Mechanisms Leading to Soft and Hard Internal Shorts

Zhang

Sahraei

Wang

2016

Sci Rep

137

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Separator integrity is an important factor in preventing internal short circuit in lithium-ion batteries. Local penetration tests (nail or conical punch) often produce presumably sporadic results, where in exactly similar cell and test set-ups one cell goes to thermal runaway while the other shows minimal reactions. We conducted an experimental study of the separators under mechanical loading, and discovered two distinct deformation and failure mechanisms, which could explain the difference in short circuit characteristics of otherwise similar tests. Additionally, by investigation of failure modes, we provided a hypothesis about the process of formation of local “soft short circuits” in cells with undetectable failure. Finally, we proposed a criterion for predicting onset of soft short from experimental data.

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confidence: 99%

Li-ion Battery Separators, Mechanical Integrity and Failure Mechanisms Leading to Soft and Hard Internal Shorts

Zhang

Sahraei

Wang

2016

Sci Rep

137

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“…Li-ion battery (LIB) separators are porous membranes that electronically isolate the positive and negative electrodes yet allow ionic transport between them. , Most common are polyolefin separators, < 25 μm-thick membranes of polyethylene (PE) and/or polypropylene (PP) having a complex three-dimensional structure with porosities, ε, of ∼40%. , To increase their mechanical, thermal, or electrochemical stability or to improve their ion transport properties, PE and PP separators have been coated with metal oxide or ceramic nanoparticles, , plasma treated, ,, or coated or gelled with micrometer-thick layers of ion-conducting polymers…”

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confidence: 99%

“…1,2 Most common are polyolefin separators, < 25 μm-thick membranes of polyethylene (PE) and/or polypropylene (PP) having a complex three-dimensional structure with porosities, ε, of ∼40%. 2,3 To increase their mechanical, thermal, or electrochemical stability or to improve their ion transport properties, PE and PP separators have been coated with metal oxide or ceramic nanoparticles, 4,5 plasma treated, 4,6,7 or coated or gelled with micrometer-thick layers of ion-conducting polymers. 8 The improvement of the lithium transport through the separator upon polymer and colloid modifications presents a paradox.…”

mentioning

confidence: 99%

Improving Ionic Conductivity and Lithium-Ion Transference Number in Lithium-Ion Battery Separators

Zahn¹,

Lagadec²,

Heß³

et al. 2016

ACS Appl. Mater. Interfaces

145

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The microstructure of lithium-ion battery separators plays an important role in separator performance; however, here we show that a geometrical analysis falls short in predicting the lithium-ion transport in the electrolyte-filled pore space. By systematically modifying the surface chemistry of a commercial polyethylene separator while keeping its microstructure unchanged, we demonstrate that surface chemistry, which alters separator-electrolyte interactions, influences ionic conductivity and lithium-ion transference number. Changes in separator surface chemistry, particularly those that increase lithium-ion transference numbers can reduce voltage drops across the separator and improve C-rate capability.

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“…However, the thin separator will lead to poor mechanical properties such as tensile strength and puncture strength. Excellent tensile strength can maintain the integrity when assembling the cells with separators. , Puncture strength as an essential property of the separators is very important to prevent the internal short-circuit because of the formation and growth of lithium dendrites.…”

Section: Resultsmentioning

confidence: 99%

Water-Based Organic–Inorganic Hybrid Coating for a High-Performance Separator

Chen¹,

Shi²,

Zhou

et al. 2016

ACS Sustainable Chem. Eng.

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With the development of electric vehicles, the traditional polyolefin separators can not meet the increasing requirements of lithium ion batteries with high power density, high energy density, and high safety performance. Herein, a novel water-based binder is synthesized by grafting carboxyl groups onto cellulose diacetate. When the polyethylene (PE) separator is coated by this binder and SiO 2 nanoparticles, the thermal shrinkage of the modified separator is observed to be almost 0% after exposure at 200°C for 30 min. The puncture strength significantly increase from 5.10 MPa (PE separator) to 7.64 MPa. More importantly, the capacity retention of the cells assembled with modified separators after 100 cycles at 0.5 C increase from 73.3% (cells assembled with PE separator) to 81.6%, owing to the excellent electrolyte uptake and the good compatibility with lithium electrode. Besides, the modified separator shows excellent surface stability after 100 cycles. Considering the above excellent properties, this composite separator shows high potential to be used in lithium ion batteries with high power density and safety.

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Manufacture and Surface Modification of Polyolefin Separator

Cited by 6 publications

References 23 publications

Li-ion Battery Separators, Mechanical Integrity and Failure Mechanisms Leading to Soft and Hard Internal Shorts

Li-ion Battery Separators, Mechanical Integrity and Failure Mechanisms Leading to Soft and Hard Internal Shorts

Improving Ionic Conductivity and Lithium-Ion Transference Number in Lithium-Ion Battery Separators

Water-Based Organic–Inorganic Hybrid Coating for a High-Performance Separator

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