bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyaniline / Nickel Ferrite / Nitrogen Doped Graphene Ternary Composite for Supercapacitors
Authors: Xia Xifeng , Tong Luyou , Lei Wu , Hao Qingli 
Published: February 2020

AbstractElectrode materials are the most important components which greatly affect the capacity, power density and energy density of electrochemical energy storage devices. Lithium ion capacitors combining the advantages of lithium ion battery and supercapacitor, have been widely investigated recently due to their high energy density and high power density [1,2]. Herein, polyaniline / nickel ferrite / nitrogen doped graphene (PNFNG) ternary composite material and nitrogen doped graphene material were prepared by hydrothermal method and in situ polymerization [3]. The specific capacitance of PNFNG is 667 F/g at 0.1A/g in a two-electrode symmetric system tested in KOH aqueous electrolyte. The capacitance loses only 5% after repeating test for 5,000 cycles at a high current density of 5A/g. The energy density of the symmetric supercapacitor can reach 23 Wh/kg at a power density of 28 W/kg. With comparison, a lithium ion hybrid capacitor was assembled with the ternary composite as an anode and activated carbon as a cathode, and the organic electrolyte. The energy density of the hybrid capacitor reaches 104.4 Wh/g when its power density is 300 W/kg at 0.3A/g, respectively. Meanwhile, the capacitance of the hybrid capacitor is 80.3 F/g. The capacitance can keep 72% after 700 cycles at 0.3A/g.

Acknowledgements

The work was supported by the National Natural Science Foundation of China (Nos. 21073092, 21103092), Program for NCET-12-0629, Ph.D. Program Foundation of Ministry of Education of China (No.20133219110018), the Science and Technology Support Plan (No. BE2013126).

References

[1] Ma Y, Chang H, Zhang M, et al. Graphene‐Based Materials for Lithium‐Ion Hybrid Supercapacitors[J]. Advanced Materials, 2015, 27(36): 5296-5308.
[2] Aravindan V, Gnanaraj J, Lee Y S, et al. Insertion-type electrodes for nonaqueous Li-ion capacitors[J]. Chemical reviews, 2014, 114(23): 11619-11635.
[3] Wang W, Hao Q, Lei W, Xia X, Wang X.Ternary nitrogen-doped graphene/nickel ferrite/polyaniline nanocomposites for high-performance supercapacitors. Journal of Power Source, 2014, 269, 250-259.
Simultaneous Production of High-Performance Flexible Textile Electrodes and Fiber Electrodes for Wearable Energy Storage
Authors: Xu Chengjun , Dong Liubing 
Published: February 2020

Flexible supercapacitors are important energy storage devices used for wearable and smart electronics. Various flexible supercapacitors have been prepared, including fiber supercapacitors, paper-like supercapacitors, three-dimensional aerogel materials based supercapacitors and textile supercapacitors. During them, fiber supercapacitors can be utilized in micro-devices, while textile supercapacitors are suitable for large-sized energy storage. To fabricate the flexible supercapacitors, the key lies in the acquirement of flexible electrodes, e.g., flexible fiber electrodes and textile electrodes. In this text, an effective strategy was proposed for the simultaneous productions of high-performance flexible textile electrodes and fiber electrodes. The prepared textile electrodes are textile/CNTs and textile/MnO2/CNTs composite textiles. During them, textile/MnO2/CNTs textile electrode/supercapacitor displays outstanding areal capacitances up to 3 F cm-2 and energy densities, and highly conductive textile is suitable for fabricating thicker electrode for supercapacitors with the high power. Scalable preparation of fiber electrodes was easily realized by dismantling textiles. In addition, the textile electrodes and fiber electrodes possess a long operation life and outstanding flexibility. Electrochemical properties of the electrodes may be further improved by optimization of MnO2, CNTs and polymers on the textiles. Despite of this, the present work is promising to promote the development of flexible electrodes and flexible energy storage devices.ercapacitors.[1-4]

Reference
[1] L. Dong, C. Xu*, et al. Adv Mater, 2016, 28, 1675.
[2] L. Dong, C. Xu*, et al. J Mater Chem A, 2015, 3, 4729.
[3] L. Dong, C. Xu*, et al. J Mater Chem A, 2016, 4, 4659.
[4] L. Dong, C. Xu*, et al. Carbon, 2015, 90, 164
Acknowledgements: We thank the financial surppots from NSFC, 973, and Shenzhen Technical Plan Projects.
Pseudohalide-Based Electrolytes for High-Energy Electrochemical Capacitors
Authors: Fic Krzysztof , Gorska Barbara , Bujewska Paulina , Béguin François , Frackowiak Elzbieta 
Published: February 2020

Redox-active electrolytes and additives offer a large selection of available species serving for supercapacitor energy enhancement. The first group refers to typical organic compounds like hydroquinone with isomeric forms. There are also several reports on methylene blue and indigo carmine compounds tested on multi-walled carbon nanotubes. Nevertheless, these organic admixtures have limited solubility in water, and/or their bulkiness restricts adsorption at the interface. Apart from organic molecules, another group of electroactive species includes halide ions. Initially, the iodide/iodine and bromine/bromide redox couples were introduced to supercapacitors. To the best of our knowledge, this is the first report on the employment of alkali metal and ammonium thiocyanates (SCN-) aqueous solutions serving as an electrolyte for supercapacitors. The investigation presents a comprehensive study including the effect of salt concentration, the impact of counter anion type (K+, Na+, Li+ and NH4
+), the influence of applied current collectors as well as the effectiveness of asymmetric configuration. Our research proves that symmetric AC/AC system can easily operate up to 1.6 V with high capacitance and great cyclability. The thiocyanate redox shuttle with formal redox potential at +0.77 V vs. SHE preserves the positive electrode against oxidation and contrarily to iodides or bromides, oxidized SCN- specimen (e.g. polythiocyanogen) in a polymeric form does not evaporate from the system (unlike I2 or Br2). A comparative study on the effect of salt concentration and dependence on the type of current collectors (gold, titanium, and stainless steel) was performed using the KSCN aqueous solutions at various concentrations (1-7 mol∙L-1). It has been demonstrated that the highest concentration of SCN- specimen (7 mol∙L-1) preserved the best performance whatever the current collector used. However, on Ti and stainless steel current collectors, the activity of SCN- seems to be slightly reduced and more ‘capacitive’ profile has been observed. More in-depth studies demonstrated that the system based on 7 mol∙L-1 KSCN aqueous solution preserved high capacitance values even at 10 A∙g-1 current load and retained high energy density (~30 Wh∙kg-1) up to 10 kW∙kg-1 of power rate. Furthermore, we observed that kind of current collector strongly influences the cycle life of the system. Although the gold current collectors provided the highest capacitance during first 1000 cycles, their cyclability is limited to 2 000 cycles. For stainless steel-based systems, the capacitance retention reached 10 000 cycles at 1.6V voltage range.
High Performance Supercapacitor with the Activated Carbon Particle/Polymer Composite
Authors: Jang Yunseok , Kim Kwang-Young 
Published: February 2020

In recent years, supercapacitors are widely studied for memory backup systems, hybrid electric vehicles and fuel cell vehicles. Supercapacitor electrodes are usually made to coat the activated carbon sludge on the current collect electrodes. And the activated carbon sludge is composed of the activated carbon particle, polymer binder and high conductivity materials. Polyvinylidene fluoride (PVDF) is usually used as the polymer binder in the activated carbon based supercapacitors. The PVDF is an insulator material, but the activated carbon is a conducting material. The reduced conductivity as adding the PVDF is enhanced by adding other high conductivity materials such as conductive carbon black. In this presentation, we propose a composite system based on the activated carbon and the crosslinkable polymer binder for high performance supercapacitor electrodes. We used the crosslinkable polymer binder instead of the PVDF binder and conductive carbon black to form the activated carbon clusters. The crosslinkable polymer binder has a merit such as minimizing the binder contents. We minimized the crosslinkable polymer binder contents to overcome the reduced conductivity of activated carbon clusters. And we demonstrate the effects of the minimized crosslinkable polymer binder on the electrical properties of supercapacitor electrodes. Acknowledgments This study was supported by the R&D program of the Korea Research Council for Industrial Science and Technology of Republic of Korea (Grant 2015K000217/ 10052802/ KM3710/ NK186C/ SC1130/ MO5970/ NM8270).
Comparative Study with Phenol and Furfural Resin-Based Active Carbon for High Density Electric Double Layer Capacitor
Authors: Nakazawa Takafumi , Nishimura Kouhei , Saito Takeyasu , Okamoto Naoki , Ide Isamu , Onishi Yoshikazu , Nishikawa Masanobu 
Published: February 2020

Electric double layer capacitor (EDLC) has been attracted much attention as one of the most promising high power and durable energy storage devices. However, low energy density is the major drawback, therefore, the optimization of specific surface area, nanoscale and mesoscale pore volume should be necessary to improve electrostatic capacity and reliability.

In this study, we carburized thermosetting resin-based particles (phenol resin and furfural resin, 10 µm in diameter) in N2 atmosphere in three hour (temperature rising rate 1ºC /min) at 400 ºC or 600ºC. Then, we treated carburized particle by three kinds of methods, KOH activation (KOH: samples = 4: 1 in weight ratio), CO2 activation or a combination of KOH and CO2 activation (KOH+CO2 activation). All activation methods were performed for 30 minutes at 800ºC or 850ºC (temperature rising rate 10ºC /min). Also, some samples were treated in the acid solution (Sulfuric acid: nitric acid = 3:1 in volume ratio) for 30 minutes at 60 ºC before KOH activation. Specific surface area/pore size distribution measurement was performed by N2 adsorption method. Elemental analysis was done by using to determine CHNO fraction. We prepared coin shaped carbon electrode (12 mm in diameter, from 8:1:1 mixture of active carbon, carbon black, and PTFE), and investigated the electrostatic characteristics of the capacitors in 6M KOH to elucidate the relationship between characteristic structure properties and electrochemical.
We obtained large specific surface area as 1253 m2/g and 1240 m2/g in phenol resin by KOH activation and KOH+CO2 activation, respectively, however, did 515 m2/g by CO2 activation. The mesopore volume to total pore volume ratio of (12.8 %) KOH+CO2 activation method is larger than KOH activated method (11.5 %), suggesting that CO2 activation after the KOH activation increase pore size. Electrostatic capacity was 125 F/g and 158 F/g KOH activation and KOH+CO2 activation, respectively, though specific surface area is almost the same with both cases. This same trend was also seen with furfural resin. Electrostatic capacity was 163 F/g with phenol resin and 119 F/g with furfural resin at 20mA/g.

The specific capacity became three times, from 45 F/g to 153 F/g by introducing acid-treatment before KOH activation with furfural resin. Oxygen contents by elemental analysis also became three times. The results suggested that active carbon surface having an oxygen containing functional groups enhance capacitor performances.
Insights into Fast Lithium and Sodium-Ion Conduction in Solid Electrolyte and Cathode Materials
Authors: Islam M. Saiful 
Published: February 2020

Major advances in rechargeable batteries require the discovery and characterisation of new materials. It is clear that a complete understanding of the properties of electrode and electrolyte materials for both Li- and Na-ion batteries requires fundamental knowledge of their underlying structural, ion diffusion and surface properties on the atomic- and nano-scales. In this context, advanced materials modelling [1] combined with structural and electrochemical techniques are now powerful tools for investigating these properties. This talk will highlight recent studies [2,3] in the following areas: (i) structural and mechanistic insights into fast lithium-ion conduction in Li4SiO4-Li3PO4 solid electrolytes; (ii) ion diffusion pathways in polyanionic cathode materials such as Li-sulfates (e.g. LiFeSO4OH) and Na-phosphates (e.g. Na2FePO4F, NaFePO4).
References
[1] M.S. Islam; C.A.J. Fisher, Chem. Soc. Rev., 43, (2014) 185.
[2] Y. Deng et al., J. Amer. Chem. Soc., 137 (2015) 9136.
[3] S.M. Wood et al., J.
Phys. Chem. C., 119 (2015) 15935.
In Operando Studies for the Strategic Development of High Performance Lithium/Sulfur Batteries
Authors: Kim Chi-Su , Marceau Hugues , Hovington Pierre , Zhu Wen , Paolella Andrea , Guerfi Abdelbast , Vijh Ashok , Zaghib Karim 
Published: February 2020

Li-S battery has attracted intensive attentions during the past decades as a strong candidate that may overcome the limit of current lithium-ion battery technology. In spite of its promises, a number of challenges still remain unsolved hindering the commercialization of Li-S batteries in near future, especially for the EV applications. It is generally accepted that the technical problems of Li-S battery are related with the intrinsic nature of conversion reactions, like low conductivity, poor diffusivity and significant morphology change, along with the unique properties of sulfur chemistry which include high solubility and strong reactivity of polysulphide species in organic solvents. However, fundamental mechanisms behind the limited performance of Li-S batteries are not fully understood and remain controversial according to the analytical methods and the specific experimental conditions. Since the charge-discharge electrochemical reaction in Li-S batteries involves complicated chemical reactions in bulk electrolyte, ex-situ analysis does not reflect the actual situation inside the battery, due to the rapid re-equilibrium of the reaction species during the sample preparation process and even during the observation period. Moreover, high volatility of elemental sulfur (S8) often leads to the misinterpretation of characterization results which are obtained in the vacuum condition or with high temperature treatment.
In this study, Li/S cells were investigated with operando techniques using Scanning Electron Microscope (SEM), Ultraviolet-Visible absorption spectroscopy (UV-Vis) and Raman spectroscopy. All-solid-state polymer electrolytes were employed to design the operando cells, which allowed a real time observation of SEM images and a speciation by UV-VIS and Raman without needs for the solvent dilution. The operando SEM successfully visualizes the cross-section of Li/S polymer cell and reveals the evolution of morphology changes with cycles, as well as the aging mechanism including the migration of sulfur species and irreversible loss of active materials out of the cathode electrode. Appearance of elemental sulfur is clearly observed beyond 2.3V in the middle of charge process. The non-destructive operando UV-VIS spectroscopy demonstrates the evolution of characteristic absorption bands with progress of discharge and charge, and shows the accumulation of soluble sulphides in the electrolyte, not only high order polysulfides but also less soluble Li2S, over cycling. The inverse relationship between the intensity of S4
2- and S6
2- bands in UV-VIS spectroscopy implies that the charge and discharge reactions take place through different pathways; the formation of S4
2- is prominent during discharge and shuttle reactions, while S6
2- is more prevailing during charge.
Stabilization of High Energy Cathodes By Introducing Conformal Passivating Shells on the Surface
Authors: Kwon Bob Jin , Phillips Patrick J , Key Baris , Kim Chunjoong , Klie Robert F , Cabana Jordi 
Published: February 2020

Combined cycling stability at high energy density is required for lithium ion battery to meet the criteria for use in electric vehicles. In generally, material utilization and rate capability are enhanced at small particle sizes. [1] Reduced size of electrode materials can enhance the rate of lithium ions because of shortened diffusion pathway and increases surface area to induces facile access by the electrolyte. In contrast, chemical degradation at electrode-electrolyte interface is also facilitated by large contact area with nanoparticle electrode. Unfavorable interfacial reactions such as dissolution of active materials and decomposition of electrolyte mainly occur because the surface of active materials is energetically unstable. [2] In order to minimize side reactions that can negatively affect to electrochemical performance, replacing electrochemically inactive ions on the surface of active materials can improve the interfacial stability. However, this substitution should take place as thin passivating layers on individual particles to preserve storage capacity. [3]
Herein, we demonstrate a strategy toward the stabilization of interfaces by introducing core-shell type of nanocrystals that is composed of electroactive transition metal oxide in core and ultra-thin inactive epitaxial oxide shell on the surface. To prove this concept, we introduce layered LixCoO2 nanocrystals as a core component, with Al-rich shells as passivation layer to minimize side reaction with electrolyte. The resulting materials shows stable cycling curves as well as higher capacity retention at high rate of charging and discharging reaction compared to bare LixCoO2.
References
1. Isaac D. Scott, Yoon Seok Jung, Andrew S. Cavanagh, Yanfa Yan, Anne C. Dillon, Steven M. George, and Se-Hee Lee, Nano Letters, 414–418, 11 (2011).
2. Peter G. Bruce, Bruno Scrosati, and Jean-Marie Tarascon, Angew. Chem. Int. Ed, 2930-2946, 47 (2008).
3. Chunjoong Kim, Patrick J. Phillips, Linping Xu, Angang Dong, Raffaella Buonsanti, Robert F. Klie, and Jordi Cabana, Chem. Matter, 394-399, 27 (2014).
Figure. (a) Evolution of specific capacity (solid symbol) and coulombic efficiency (open symbol) in cycling at C/20, (b) electron microscopic image, (c) EELS for Al and (d) EELS for Co atom of LixCoO2 with Al rich shell nanocrystals.

Figure 1
Ultrathin Coating of Nitrogen and Sulfur Co-Doped Graphene Nanosheets on Polymer Separator for Suppressing Dendritic Lithium Growth in Lithium Metal Batteries
Authors: Cho Jinhyun , Shin Won-Kyung , G Kannan Aravindaraj , Kim Dong-Won 
Published: February 2020

The advent of electric vehicles and other high energy density applications has intensified the research efforts on lithium metal-based batteries, as metallic lithium can provide a high specific capacity (~3,862 mAh g-1), enabling it as a promising negative electrode for next-generation battery systems [1,2]. However, the instability of lithium electrodes is one of the greatest challenges hindering the successful development of lithium metal batteries. Lithium metal is unstable against nearly all chemical species and reacts with organic solvents and salts in liquid electrolytes. Moreover, continuous deposition and stripping of lithium may induce uncontrollable dendritic Li growth, which in turn leads to internal short circuits, failure, and eventually explosions.
In this work, we demonstrated that an ultrathin nitrogen and sulfur co-doped graphene (NSG) layer deposited on a PE separator could effectively stabilize the lithium electrode surface, suppress dendrite formation, and improve the cycling stability of lithium metal batteries. The NSG coating layer is very thin as compared to other ceramic coatings in micrometer scales, which can provide higher energy density of the cell with NSG separator. The incorporation of heteroatom dopants could induce structural deformations due to local strains induced in the carbon framework, thereby allowing for easy ionic migration while maintaining a uniform ionic flux on the Li metal surface. Moreover, the lone pair electrons in the heteroatom dopants led to the generation of negative charge, resulting in enhanced interfacial interactions between the NSG-coated separator and the lithium electrode. The NSG coating also imparted thermal stability to the PE separator, thus preventing thermal shrinkage of the separator at elevated temperature and enhancing battery safety. The cycling performance of the lithium metal cell employing a NSG coated separator was remarkably improved as compared to the cell with a pristine PE separator.

References
[1] J. -M. Tarascon, M. Armand, Nature
2001, 414, 359–367.
[2] W. Xu, J. Wang, F. Ding, X. Chen, E. Nasybulin, Y. Zhang, J. G. Zhang,. Energy Environ. Sci.
2014, 7, 513–537.
Development of Novel Noncarbonate Electrolytes for Silicon Alloy Anodes
Authors: Zhu Ye , Cheng Gang , Strand Dee 
Published: February 2020

Wildcat Discovery Technologies is developing novel electrolyte additives and noncarbonate solvent formulations that yield improved solid electrolyte interphase (SEI) layers on silicon alloy anodes. The large volumetric changes in silicon during charge/discharge cycles result in mechanical disruption of conventional SEI's leading to rapid capacity fade as the cell cycles. Novel additives that could help to form more mechanically robust SEI passivation layers, hence improving cycle life of silicon based materials are identified through the screening in propylene carbonate (PC) based electrolyte since PC is not expected to form an effective SEI layer. The additives are tested with PC to determine their efficacy. Wildcat's high throughput electrolyte formulation, cell assembly, and test capabilities enable the evaluation of hundreds of additives in a very short timeframe.
Once effective SEI additives are identified in a PC-based formulation, other non-SEI forming solvents can be evaluated. Since the additives are effective without solvent participation in SEI formation, solvents that may not be reductively stable on the anode can also be considered, opening the possibility to more oxidatively stable or less flammable solvents. Wildcat has evaluated hundreds of combinations of noncarbonate solvents with its initial silicon anode SEI additives, and identified a few very unique combinations that showed further improved cycle life over the state-of-the-art carbonate based electrolyte.
Finally, with the most promising noncarbonate solvents in hand, new electrolyte additives are screened for further improved cycle life. The new additives selection is based on the earlier additive screening in PC electrolyte. A thorough Structure Activity Relationship (SAR) study for those promising additives is carried out. This presentation will focus on the results of the additive improvement to cycle life in NMC//Si full cells, and illustrate the opportunities for novel solvent combinations. We will demonstrate the power of high throughput development of lithium ion battery advanced electrolytes within this presentation.