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13 pages, 3566 KiB

Open AccessArticle

Linear-Polyethyleneimine-Templated Synthesis of N-Doped Carbon Nanonet Flakes for High-performance Supercapacitor Electrodes

by Dengchao Xia, Junpeng Quan, Guodong Wu, Xinling Liu, Zongtao Zhang, Haipeng Ji, Deliang Chen, Liying Zhang, Yu Wang, Shasha Yi, Ying Zhou, Yanfeng Gao and Ren-hua Jin

Nanomaterials 2019, 9(9), 1225; https://doi.org/10.3390/nano9091225 - 29 Aug 2019

Cited by 11 | Viewed by 6952

Abstract

Novel N-doped carbon nanonet flakes (NCNFs), consisting of three-dimensional interconnected carbon nanotube and penetrable mesopore channels were synthesized in the assistance of a hybrid catalytic template of silica-coated-linear polyethyleneimine (PEI). Resorcinol-formaldehyde resin and melamine were used as precursors for carbon and [...] Read more.

Novel N-doped carbon nanonet flakes (NCNFs), consisting of three-dimensional interconnected carbon nanotube and penetrable mesopore channels were synthesized in the assistance of a hybrid catalytic template of silica-coated-linear polyethyleneimine (PEI). Resorcinol-formaldehyde resin and melamine were used as precursors for carbon and nitrogen, respectively, which were spontaneously formed on the silica-coated-PEI template and then annealed at 700 °C in a N₂ atmosphere to be transformed into the hierarchical 3D N-doped carbon nanonetworks. The obtained NCNFs possess high surface area (946 m² g⁻¹), uniform pore size (2–5 nm), and excellent electron and ion conductivity, which were quite beneficial for electrochemical double-layered supercapacitors (EDLSs). The supercapacitor synthesized from NCNFs electrodes exhibited both extremely high capacitance (up to 613 F g⁻¹ at 1 A g⁻¹) and excellent long-term capacitance retention performance (96% capacitive retention after 20,000 cycles), which established the current processing among the most competitive strategies for the synthesis of high performance supercapacitors. Full article

(This article belongs to the Special Issue Nanomaterials and Nanofabrication for Electrochemical Energy Storage)

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10 pages, 2368 KiB

Open AccessFeature PaperArticle

Spark Plasma Sintering of Lithium Aluminum Germanium Phosphate Solid Electrolyte and its Electrochemical Properties

by Hongzheng Zhu, Anil Prasad, Somi Doja, Lukas Bichler and Jian Liu

Nanomaterials 2019, 9(8), 1086; https://doi.org/10.3390/nano9081086 - 29 Jul 2019

Cited by 14 | Viewed by 4040

Abstract

Sodium superionic conductor (NASICON)-type lithium aluminum germanium phosphate (LAGP) has attracted increasing attention as a solid electrolyte for all-solid-state lithium-ion batteries (ASSLIBs), due to the good ionic conductivity and highly stable interface with Li metal. However, it still remains challenging to achieve high [...] Read more.

Sodium superionic conductor (NASICON)-type lithium aluminum germanium phosphate (LAGP) has attracted increasing attention as a solid electrolyte for all-solid-state lithium-ion batteries (ASSLIBs), due to the good ionic conductivity and highly stable interface with Li metal. However, it still remains challenging to achieve high density and good ionic conductivity in LAGP pellets by using conventional sintering methods, because they required high temperatures (>800 °C) and long sintering time (>6 h), which could cause the loss of lithium, the formation of impurity phases, and thus the reduction of ionic conductivity. Herein, we report the utilization of a spark plasma sintering (SPS) method to synthesize LAGP pellets with a density of 3.477 g cm⁻³, a relative high density up to 97.6%, and a good ionic conductivity of 3.29 × 10⁻⁴ S cm⁻¹. In contrast to the dry-pressing process followed with high-temperature annealing, the optimized SPS process only required a low operating temperature of 650 °C and short sintering time of 10 min. Despite the least energy and short time consumption, the SPS approach could still achieve LAGP pellets with high density, little voids and cracks, intimate grain–grain boundary, and high ionic conductivity. These advantages suggest the great potential of SPS as a fabrication technique for preparing solid electrolytes and composite electrodes used in ASSLIBs. Full article

(This article belongs to the Special Issue Nanomaterials and Nanofabrication for Electrochemical Energy Storage)

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23 pages, 6051 KiB

Open AccessArticle

Mixed-Phase MnO₂/N-Containing Graphene Composites Applied as Electrode Active Materials for Flexible Asymmetric Solid-State Supercapacitors

by Hsin-Ya Chiu and Chun-Pei Cho

Nanomaterials 2018, 8(11), 924; https://doi.org/10.3390/nano8110924 - 08 Nov 2018

Cited by 12 | Viewed by 3594

Abstract

MnO₂/N-containing graphene composites with various contents of Mn were fabricated and used as active materials for the electrodes of flexible solid-state asymmetric supercapacitors. By scanning electron microscopes (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrometer (XPS), fourier-transform [...] Read more.

MnO₂/N-containing graphene composites with various contents of Mn were fabricated and used as active materials for the electrodes of flexible solid-state asymmetric supercapacitors. By scanning electron microscopes (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrometer (XPS), fourier-transform infrared spectroscopy (FTIR) and Raman spectra, the presence of MnO₂ and N-containing graphene was verified. The MnO₂ nanostructures decorated on the N-containing graphene were of α- and γ-mixed phases. N-containing graphene was found to reduce the charge transfer impedance in the high-frequency region at the electrode/electrolyte interface (R_CT) due to its good conductivity. The co-existence of MnO₂ and N-containing graphene led to a more reduced R_CT and improved charge transfer. Both the mass loading and content of Mn in an active material electrode were crucial. Excess Mn caused reduced contacts between the electrode and electrolyte ions, leading to increased R_CT, and suppressed ionic diffusion. When the optimized mass loading and Mn content were used, the 3-NGM1 electrode exhibiting the smallest R_CT and a lower ionic diffusion impedance was obtained. It also showed a high specific capacitance of 638 F·g⁻¹ by calculation from the cyclic voltammetry (CV) curves. The corresponding energy and power densities were 372.7 Wh·kg⁻¹ and 4731.1 W·kg⁻¹, respectively. The superior capacitance property arising from the synergistic effect of mixed-phase MnO₂ and N-containing graphene had permitted the composites promising active materials for flexible solid-state asymmetric supercapacitors. Moreover, the increase of specific capacitance was found to be more significant by the pseudocapacitive MnO₂ than N-containing graphene. Full article

(This article belongs to the Special Issue Nanomaterials and Nanofabrication for Electrochemical Energy Storage)

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10 pages, 3410 KiB

Open AccessCommunication

Single-Step Direct Hydrothermal Growth of NiMoO₄ Nanostructured Thin Film on Stainless Steel for Supercapacitor Electrodes

by V. Kannan, Hyun-Jung Kim, Hyun-Chang Park and Hyun-Seok Kim

Nanomaterials 2018, 8(8), 563; https://doi.org/10.3390/nano8080563 - 24 Jul 2018

Cited by 12 | Viewed by 4134

Abstract

We report a facile and direct growth of NiMoO₄ nanostructures on a nonreactive stainless steel substrate using a single-step hydrothermal method and investigated hydrothermal growth duration effects on morphology and electrochemical characteristics. The highest specific capacitances of 341, 619, and 281 F/g [...] Read more.

We report a facile and direct growth of NiMoO₄ nanostructures on a nonreactive stainless steel substrate using a single-step hydrothermal method and investigated hydrothermal growth duration effects on morphology and electrochemical characteristics. The highest specific capacitances of 341, 619, and 281 F/g were observed for NiMoO₄ with 9, 18, and 27 h growth, respectively, at 1 A/g. Thus, grown samples preserved almost 59% of maximum specific capacitance at a high current density of 10 A/g. All samples exhibited a respectable cycling stability over 3000 charge-discharge operations. NiMoO₄ grown for 18 h exhibited 7200 W/kg peak power density at 14 Wh/kg energy density. Thus, the proposed single-step hydrothermal growth is a promising route to obtain NiMoO₄ nanostructures and other metal oxide electrodes for supercapacitor applications. Full article

(This article belongs to the Special Issue Nanomaterials and Nanofabrication for Electrochemical Energy Storage)

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14 pages, 6114 KiB

Open AccessArticle

Three-Dimensional Honeycomb-Like Porous Carbon with Both Interconnected Hierarchical Porosity and Nitrogen Self-Doping from Cotton Seed Husk for Supercapacitor Electrode

by Hui Chen, Gang Wang, Long Chen, Bin Dai and Feng Yu

Nanomaterials 2018, 8(6), 412; https://doi.org/10.3390/nano8060412 - 08 Jun 2018

Cited by 54 | Viewed by 6022

Abstract

Hierarchical porous structures with surface nitrogen-doped porous carbon are current research topics of interest for high performance supercapacitor electrode materials. Herein, a three-dimensional (3D) honeycomb-like porous carbon with interconnected hierarchical porosity and nitrogen self-doping was synthesized by simple and cost-efficient one-step KOH activation [...] Read more.

Hierarchical porous structures with surface nitrogen-doped porous carbon are current research topics of interest for high performance supercapacitor electrode materials. Herein, a three-dimensional (3D) honeycomb-like porous carbon with interconnected hierarchical porosity and nitrogen self-doping was synthesized by simple and cost-efficient one-step KOH activation from waste cottonseed husk (a-CSHs). The obtained a-CSHs possessed hierarchical micro-, meso-, and macro-pores, a high specific surface area of 1694.1 m²/g, 3D architecture, and abundant self N-doping. Owing to these distinct features, a-CSHs delivered high specific capacitances of 238 F/g and 200 F/g at current densities of 0.5 A/g and 20 A/g, respectively, in a 6 mol/L KOH electrolyte, demonstrating good capacitance retention of 84%. The assembled a-CSHs-based symmetric supercapacitor also displayed high specific capacitance of 52 F/g at 0.5 A/g, with an energy density of 10.4 Wh/Kg at 300 W/Kg, and 91% capacitance retention after 5000 cycles at 10 A/g. Full article

(This article belongs to the Special Issue Nanomaterials and Nanofabrication for Electrochemical Energy Storage)

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9 pages, 5521 KiB

Open AccessArticle

A Hollow-Structured Manganese Oxide Cathode for Stable Zn-MnO₂ Batteries

by Xiaotong Guo, Jianming Li, Xu Jin, Yehu Han, Yue Lin, Zhanwu Lei, Shiyang Wang, Lianjie Qin, Shuhong Jiao and Ruiguo Cao

Nanomaterials 2018, 8(5), 301; https://doi.org/10.3390/nano8050301 - 05 May 2018

Cited by 50 | Viewed by 9182

Abstract

Aqueous rechargeable zinc-manganese dioxide (Zn-MnO₂) batteries are considered as one of the most promising energy storage devices for large scale-energy storage systems due to their low cost, high safety, and environmental friendliness. However, only a few cathode materials have been demonstrated [...] Read more.

Aqueous rechargeable zinc-manganese dioxide (Zn-MnO₂) batteries are considered as one of the most promising energy storage devices for large scale-energy storage systems due to their low cost, high safety, and environmental friendliness. However, only a few cathode materials have been demonstrated to achieve stable cycling for aqueous rechargeable Zn-MnO₂ batteries. Here, we report a new material consisting of hollow MnO₂ nanospheres, which can be used for aqueous Zn-MnO₂ batteries. The hollow MnO₂ nanospheres can achieve high specific capacity up to ~405 mAh g⁻¹ at 0.5 C. More importantly, the hollow structure of birnessite-type MnO₂ enables long-term cycling stability for the aqueous Zn-MnO₂ batteries. The excellent performance of the hollow MnO₂ nanospheres should be due to their unique structural properties that enable the easy intercalation of zinc ions. Full article

(This article belongs to the Special Issue Nanomaterials and Nanofabrication for Electrochemical Energy Storage)

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12 pages, 19549 KiB

Open AccessArticle

One-Dimensional Porous Silicon Nanowires with Large Surface Area for Fast Charge–Discharge Lithium-Ion Batteries

by Xu Chen, Qinsong Bi, Muhammad Sajjad, Xu Wang, Yang Ren, Xiaowei Zhou, Wen Xu and Zhu Liu

Nanomaterials 2018, 8(5), 285; https://doi.org/10.3390/nano8050285 - 27 Apr 2018

Cited by 44 | Viewed by 6045

Abstract

In this study, one-dimensional porous silicon nanowire (1D–PSiNW) arrays were fabricated by one-step metal-assisted chemical etching (MACE) to etch phosphorus-doped silicon wafers. The as-prepared mesoporous 1D–PSiNW arrays here had especially high specific surface areas of 323.47 m²·g⁻¹ and were applied [...] Read more.

In this study, one-dimensional porous silicon nanowire (1D–PSiNW) arrays were fabricated by one-step metal-assisted chemical etching (MACE) to etch phosphorus-doped silicon wafers. The as-prepared mesoporous 1D–PSiNW arrays here had especially high specific surface areas of 323.47 m²·g⁻¹ and were applied as anodes to achieve fast charge–discharge performance for lithium ion batteries (LIBs). The 1D–PSiNWs anodes with feature size of ~7 nm exhibited reversible specific capacity of 2061.1 mAh·g⁻¹ after 1000 cycles at a high current density of 1.5 A·g⁻¹. Moreover, under the ultrafast charge–discharge current rate of 16.0 A·g⁻¹, the 1D–PSiNWs anodes still maintained 586.7 mAh·g⁻¹ capacity even after 5000 cycles. This nanoporous 1D–PSiNW with high surface area is a potential anode candidate for the ultrafast charge–discharge in LIBs with high specific capacity and superior cycling performance. Full article

(This article belongs to the Special Issue Nanomaterials and Nanofabrication for Electrochemical Energy Storage)

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Other

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9 pages, 1400 KiB

Open AccessLetter

High Electrochemical Performance Phosphorus-Oxide Modified Graphene Electrode for Redox Supercapacitors Prepared by One-Step Electrochemical Exfoliation

by Lei Zu, Xing Gao, Huiqin Lian, Xiaomin Cai, Ce Li, Ying Zhong, Yicheng Hao, Yifan Zhang, Zheng Gong, Yang Liu, Xiaodong Wang and Xiuguo Cui

Nanomaterials 2018, 8(6), 417; https://doi.org/10.3390/nano8060417 - 09 Jun 2018

Cited by 19 | Viewed by 4072

Abstract

Phosphorus oxide modified graphene was prepared by one-step electrochemical anodic exfoliation method and utilized as electrode in a redox supercapacitor that contained potassium iodide in electrolytes. The whole preparation process was completed in a few minutes and the yield was about 37.2%. The [...] Read more.

Phosphorus oxide modified graphene was prepared by one-step electrochemical anodic exfoliation method and utilized as electrode in a redox supercapacitor that contained potassium iodide in electrolytes. The whole preparation process was completed in a few minutes and the yield was about 37.2%. The prepared sample has better electrocatalysis activity for I⁻/I⁻₃ redox reaction than graphite due to the good charge transfer performance between phosphorus oxide and iodide ions. The maximum discharge specific capacitance is 1634.2 F/g when the current density is 3.5 mA/cm² and it can keep at 463 F/g after 500 charging–discharging cycles when the current density increased about three times. Full article

(This article belongs to the Special Issue Nanomaterials and Nanofabrication for Electrochemical Energy Storage)

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