Research

12 pages, 5974 KiB

Open AccessArticle

Nylon-Based Composite Gel Membrane Fabricated via Sequential Layer-By-Layer Electrospinning for Rechargeable Lithium Batteries with High Performance

by Sainan Qin, Yuqi Wang, Xu Wu, Xingpeng Zhang, Yusong Zhu, Nengfei Yu, Yi Zhang and Yuping Wu

Polymers 2020, 12(7), 1572; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12071572 - 15 Jul 2020

Cited by 9 | Viewed by 2947

Abstract

With the raw materials of poly(vinylidene-co-hexafluoropropylene) (P(VDF-HFP)) and polyamide 6 (PA6, nylon 6), a sandwich-structured composite membrane, PA6/P(VDF-HFP)/PA6, is fabricated via sequential layer-by-layer electrospinning. The nylon-based composite exhibits high absorption to organic liquid electrolyte (270 wt%) owing to its high porosity (90.35%), good [...] Read more.

With the raw materials of poly(vinylidene-co-hexafluoropropylene) (P(VDF-HFP)) and polyamide 6 (PA6, nylon 6), a sandwich-structured composite membrane, PA6/P(VDF-HFP)/PA6, is fabricated via sequential layer-by-layer electrospinning. The nylon-based composite exhibits high absorption to organic liquid electrolyte (270 wt%) owing to its high porosity (90.35%), good mechanical property (17.11 MPa), and outstanding shut-down behavior from approximately 145 to 230 °C. Moreover, the dimensional shrink of a wet PA6 porous membrane immersed into liquid electrolyte is cured due to the existence of the P(VDF-HFP) middle layer. After swelling by the LiPF₆-based organic liquid electrolyte, the obtained PA6/P(VDF-HFP)/PA6-based gel polymer electrolytes (GPE) shows high ionic conductivity at room temperature (4.2 mS cm⁻¹), a wide electrochemical stable window (4.8 V), and low activation energy for Li⁺ ion conduction (4.68 kJ mol⁻¹). Benefiting from the precise porosity structure made of the interlaced electrospinning nanofibers and the superior physicochemical properties of the nylon-based composite GPE, the reversible Li⁺ ion dissolution/deposition behaviors between the GPE and Li anode are successfully realized with the Li/Li symmetrical cells (current density: 1.0 mA cm⁻²; areal capacity: 1.0 mAh cm⁻²) proceeding over 400 h at a polarization voltage of no more than 70 mV. Furthermore, the nylon-based composite GPE in assembled Li/LiFePO₄ cells displays good electrochemical stability, high discharge capacity, good cycle durability, and high rate capability. This research provides a new strategy to fabricate gel polymer electrolytes via the electrospinning technique for rechargeable lithium batteries with good electrochemical performance, high security, and low cost. Full article

(This article belongs to the Special Issue Polymer/Graphene for High-Performance Lithium Ion or Sodium Ion Batteries)

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12 pages, 4932 KiB

Open AccessArticle

Applications of Long-Length Carbon Nano-Tube (L-CNT) as Conductive Materials in High Energy Density Pouch Type Lithium Ion Batteries

by Shan-Ho Tsai, Ying-Ru Chen, Yi-Lin Tsou, Tseng-Lung Chang, Hong-Zheng Lai and Chi-Young Lee

Polymers 2020, 12(7), 1471; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12071471 - 30 Jun 2020

Cited by 6 | Viewed by 3265

Abstract

Lots of lithium ion battery (LIB) products contain lithium metal oxide LiNi₅Co₂Mn₃O₂ (LNCM) as the positive electrode’s active material. The stable surface of this oxide results in high resistivity in the battery. For this reason, conductive [...] Read more.

Lots of lithium ion battery (LIB) products contain lithium metal oxide LiNi₅Co₂Mn₃O₂ (LNCM) as the positive electrode’s active material. The stable surface of this oxide results in high resistivity in the battery. For this reason, conductive carbon-based materials, including acetylene black and carbon black, become necessary components in electrodes. Recently, carbon nano-tube (CNT) has appeared as a popular choice for the conductive carbon in LIB. However, a large quantity of the conductive carbon, which cannot provide capacity as the active material, will decrease the energy density of batteries. The ultra-high cost of CNT, compared to conventional carbon black, is also a problem. In this work, we are going to introduce long-length carbon nano-tube s(L-CNT) into electrodes in order to design a reduced-amount conductive carbon electrode. The whole experiment will be done in a 1Ah commercial type pouch LIB. By decreasing conductive carbon as well as increasing the active material in the positive electrode, the energy density of the LNCM-based 1Ah pouch type LIB, with only 0.16% of L-CNT inside the LNCM positive electrode, could reach 224 Wh/kg and 549 Wh/L, in weight and volume energy density, respectively. Further, this high energy density LIB with L-CNT offers stable cyclability, which may constitute valuable progress in portable devices and electric vehicle (EV) applications. Full article

(This article belongs to the Special Issue Polymer/Graphene for High-Performance Lithium Ion or Sodium Ion Batteries)

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13 pages, 3572 KiB

Open AccessArticle

Effects of Graphene Nanosheets with Different Lateral Sizes as Conductive Additives on the Electrochemical Performance of LiNi_0.5Co_0.2Mn_0.3O₂ Cathode Materials for Li Ion Batteries

by Ting-Hao Hsu and Wei-Ren Liu

Polymers 2020, 12(5), 1162; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12051162 - 19 May 2020

Cited by 6 | Viewed by 3444

Abstract

In this study, we focus on lateral size effects of graphene nanosheets as conductive additives for LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) cathode materials for Li-ion batteries. We used two different lateral sizes of graphene, 13 (GN-13) and 28 µm [...] Read more.

In this study, we focus on lateral size effects of graphene nanosheets as conductive additives for LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) cathode materials for Li-ion batteries. We used two different lateral sizes of graphene, 13 (GN-13) and 28 µm (GN-28). It can be found that the larger sheet sizes of graphene nanosheets give a poorer rate capability. The electrochemical measurements indicate that GN-13 delivers an average capacity of 189.8 mAh/g at 0.1 C and 114.2 mAh/g at 2 C and GN-28 exhibits an average capacity of 179.4 mAh/g at 0.1 C and only 6 mAh/g at 2 C. Moreover, according to the results of alternating current (AC) impedance, it can be found that the GN-28 sample has much higher resistance than that of GN-13. The reason might be attributed to that GN-28 has a longer diffusion distance of ion transfer and the mismatch of particle size between NCM and GN-28. The corresponding characterization might provide important reference for Li-ion battery applications. Full article

(This article belongs to the Special Issue Polymer/Graphene for High-Performance Lithium Ion or Sodium Ion Batteries)

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13 pages, 2268 KiB

Open AccessArticle

A Holey Graphene Additive for Boosting Performance of Electric Double-Layer Supercapacitors

by Jun-Bin Huang, Jagabandhu Patra, Ming-Hsien Lin, Ming-Der Ger, Yih-Ming Liu, Nen-Wen Pu, Chien-Te Hsieh, Meng-Jey Youh, Quan-Feng Dong and Jeng-Kuei Chang

Polymers 2020, 12(4), 765; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12040765 - 01 Apr 2020

Cited by 8 | Viewed by 3223

Abstract

We demonstrate a facile and effective method, which is low-cost and easy to scale up, to fabricate holey graphene nanosheets (HGNSs) via ultrafast heating during synthesis. Various heating temperatures are used to modify the material properties of HGNSs. First, we use HGNSs as [...] Read more.

We demonstrate a facile and effective method, which is low-cost and easy to scale up, to fabricate holey graphene nanosheets (HGNSs) via ultrafast heating during synthesis. Various heating temperatures are used to modify the material properties of HGNSs. First, we use HGNSs as the electrode active materials for electric double-layer capacitors (EDLCs). A synthesis temperature of 900 °C seems to be optimal, i.e., the conductivity and adhesion of HGNSs reach a compromise. The gravimetric capacitance of this HGNS sample (namely HGNS-900) is 56 F·g⁻¹. However, the volumetric capacitance is low, which hinders its practical application. Secondly, we incorporate activated carbon (AC) into HGNS-900 to make a composite EDLC material. The effect of the AC:HGNS-900 ratio on the capacitance, high-rate performance, and cycling stability are systematically investigated. With a proper amount of HGNS-900, both the electrode gravimetric and volumetric capacitances at high rate charging/discharging are clearly higher than those of plain AC electrodes. The AC/HGNS-900 composite is a promising electrode material for nonaqueous EDLC applications. Full article

(This article belongs to the Special Issue Polymer/Graphene for High-Performance Lithium Ion or Sodium Ion Batteries)

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13 pages, 4652 KiB

Open AccessArticle

Effect of Polyaniline on Sulfur/Sepiolite Composite Cathode for Lithium-Sulfur Batteries

by Kalaiselvi Chelladurai, Priyanka Venkatachalam, Subadevi Rengapillai, Wei-Ren Liu, Chia-Hung Huang and Sivakumar Marimuthu

Polymers 2020, 12(4), 755; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12040755 - 31 Mar 2020

Cited by 14 | Viewed by 2813

Abstract

Composite materials with a stable network structure consisting of natural sepiolite (Sp) powders (both sieved sepiolite and post-treated sepiolite), sulfur(S), and conductive polymer Polyaniline (PAni) have been successfully synthesized using a simple heat treatment. The morphology of composites illustrates that the sepiolite is [...] Read more.

Composite materials with a stable network structure consisting of natural sepiolite (Sp) powders (both sieved sepiolite and post-treated sepiolite), sulfur(S), and conductive polymer Polyaniline (PAni) have been successfully synthesized using a simple heat treatment. The morphology of composites illustrates that the sepiolite is composed of many needle-like fibrous clusters. The initial discharge capacity of the post-treated sepiolite/sulfur/PAni composite is about 1230 mA h g⁻¹ at 0.1 C, and it remains at 826 mA h g⁻¹ even after 40 cycles with the corresponding coulombic efficiency above 97%. Such performance is attributed to the specific porous structure, outstanding adsorption characteristics, and excellent ion exchange capability of sepiolite, as well as the excellent conductivity of PAni. In addition, the PAni coating has a pinning effect on sulfur, which influences the consumption of the active mass and enhances the cycling constancy and the coulombic efficiency of the composite material at elevated current rates. Full article

(This article belongs to the Special Issue Polymer/Graphene for High-Performance Lithium Ion or Sodium Ion Batteries)

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13 pages, 3618 KiB

Open AccessArticle

Theoretical Insights into the Structures and Capacitive Performances of Confined Ionic Liquids

by Jie Yang, Yajun Ding, Cheng Lian, Sanjiu Ying and Honglai Liu

Polymers 2020, 12(3), 722; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12030722 - 24 Mar 2020

Cited by 6 | Viewed by 3226

Abstract

Room-temperature ionic liquids (RTILs) together with nano-porous electrodes are the most promising materials for supercapacitors and batteries. Many theoretical works have addressed the structures and performances of RTILs inside nanopores. However, only limited attention has been given to how the dispersion forces of [...] Read more.

Room-temperature ionic liquids (RTILs) together with nano-porous electrodes are the most promising materials for supercapacitors and batteries. Many theoretical works have addressed the structures and performances of RTILs inside nanopores. However, only limited attention has been given to how the dispersion forces of RTILs influence the behavior of ions inside the slit pores. Toward this aim, we investigate the effects of various dispersion forces between ions on the macroscopic structures in nanoconfinement and the capacitance performance of supercapacitors by the classical density functional theory (CDFT). The results show that the dispersion force can significantly change the mechanism of the charging process and even the shape of differential capacitance curves. In addition, the voltage-dependent structures of RTILs with appropriate dispersion force appears in a given silt pore, which leads to extremely high capacitance and enhances the energy storage density. We hope that this work could further offer guidance for the optimizing of electrolytes for electrical double layer capacitors, like tuning the dispersion force between ions by adding/removing certain chemical groups on the cations and anions of RTILs. Full article

(This article belongs to the Special Issue Polymer/Graphene for High-Performance Lithium Ion or Sodium Ion Batteries)

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13 pages, 24226 KiB

Open AccessArticle

High Capacity Prismatic Type Layered Electrode with Anionic Redox Activity as an Efficient Cathode Material and PVdF/SiO₂ Composite Membrane for a Sodium Ion Battery

by Arjunan Ponnaiah, Subadevi Rengapillai, Diwakar Karuppiah, Sivakumar Marimuthu, Wei-Ren Liu and Chia-Hung Huang

Polymers 2020, 12(3), 662; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12030662 - 16 Mar 2020

Cited by 2 | Viewed by 2862

Abstract

A prismatic type layered Na_2/3Ni_1/3Mn_2/3O₂ cathode material for a sodium ion battery is prepared via two different methods viz., the solid state and sol–gel method with dissimilar surface morphology and a single phase crystal structure. It [...] Read more.

A prismatic type layered Na_2/3Ni_1/3Mn_2/3O₂ cathode material for a sodium ion battery is prepared via two different methods viz., the solid state and sol–gel method with dissimilar surface morphology and a single phase crystal structure. It shows tremendous electrochemical chattels when studied as a cathode for a sodium-ion battery of an initial specific discharge capacity of 244 mAh g⁻¹ with decent columbic efficiency of 98% up to 250 cycles, between the voltage range from 1.8 to 4.5 V (Na⁺/Na) at 0.1 C under room temperature. It is much higher than its theoretical value of 173 mAh g⁻¹ and also than in the earlier reports (228 m Ah g⁻¹). The full cell containing this material exhibits 800 mAh g⁻¹ at 0.1 C and withstands until 1000 cycles with the discharge capacity of 164 mAh g⁻¹. The surpassing capacity was expected by the anionic (oxygen) redox process, which elucidates the higher capacity based on the charge compensation phenomenon. Full article

(This article belongs to the Special Issue Polymer/Graphene for High-Performance Lithium Ion or Sodium Ion Batteries)

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13 pages, 5019 KiB

Open AccessArticle

Spinel rGO Wrapped CoV₂O₄ Nanocomposite as a Novel Anode Material for Sodium-Ion Batteries

by Rasu Muruganantham, Jeng-Shin Lu and Wei-Ren Liu

Polymers 2020, 12(3), 555; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12030555 - 03 Mar 2020

Cited by 14 | Viewed by 4172

Abstract

Binary mixed transition-based metal oxides have some of the most potential as anode materials for rechargeable advanced battery systems due to their high theoretical capacity and tremendous electrochemical performance. Nonetheless, binary metal oxides still endure low electronic conductivity and huge volume expansion during [...] Read more.

Binary mixed transition-based metal oxides have some of the most potential as anode materials for rechargeable advanced battery systems due to their high theoretical capacity and tremendous electrochemical performance. Nonetheless, binary metal oxides still endure low electronic conductivity and huge volume expansion during the charge/discharge processes. In this study, we synthesized a reduced graphene oxide (rGO)-wrapped CoV₂O₄ material as the anode for sodium ion batteries. The X-ray diffraction analyses revealed pure-phased CoV₂O₄ (CVO) rGO-wrapped CoV₂O₄ (CVO/rGO) nanoparticles. The capacity retention of the CVO/rGO composite anode demonstrated 81.6% at the current density of 200 mA/g for more than 1000 cycles, which was better than that of the bare one of only 73.5% retention. The as-synthesized CVO/rGO exhibited remarkable cyclic stability and rate capability. The reaction mechanism of the CoV₂O₄ anode with sodium ions was firstly studied in terms of cyclic voltammetry (CV) and ex situ XRD analyses. These results articulated the manner of utilizing the graphene oxide-coated spinel-based novel anode-CoV₂O₄ as a potential anode for sodium ion batteries. Full article

(This article belongs to the Special Issue Polymer/Graphene for High-Performance Lithium Ion or Sodium Ion Batteries)

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12 pages, 3887 KiB

Open AccessArticle

Carbon Loaded Nano-Designed Spherically High Symmetric Lithium Iron Orthosilicate Cathode Materials for Lithium Secondary Batteries

by Diwakar Karuppiah, Rajkumar Palanisamy, Subadevi Rengapillai, Wei-Ren Liu, Chia-Hung Huang and Sivakumar Marimuthu

Polymers 2019, 11(10), 1703; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11101703 - 17 Oct 2019

Cited by 6 | Viewed by 2624

Abstract

In the present study, Li₂FeSiO₄ (LFS) cathode material has been prepared via a modified polyol method. The stabilizing nature of polyol solvent was greatly influenced to reduce the particle size (~50 nm) and for coating the carbon on the surface [...] Read more.

In the present study, Li₂FeSiO₄ (LFS) cathode material has been prepared via a modified polyol method. The stabilizing nature of polyol solvent was greatly influenced to reduce the particle size (~50 nm) and for coating the carbon on the surface of the as-mentioned materials (~10 nm). As-prepared nano-sized Li₂FeSiO₄ material deliver initial discharge capacity of 186 mAh·g⁻¹ at 1C with the coulombic efficiency of 99% and sustain up to 100 cycles with only 7 mAh·g⁻¹ is the difference of discharge capacity from its 1st cycle to 100th cycle. The rate performance illustrates the discharge capacity 280 mAh·g⁻¹ for lower C-rate (C/20) and 95 mAh·g⁻¹ for higher C-rate (2C). Full article

(This article belongs to the Special Issue Polymer/Graphene for High-Performance Lithium Ion or Sodium Ion Batteries)

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