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Blomquist, N., Alimadadi, M., Hummelgård, M., Dahlström, C., Olsen, M. & Olin, H. (2019). Effects of Geometry on Large-scale Tube-shear Exfoliation of Multilayer Graphene and Nanographite in Water. Scientific Reports, 9(1), Article ID 8966.
Open this publication in new window or tab >>Effects of Geometry on Large-scale Tube-shear Exfoliation of Multilayer Graphene and Nanographite in Water
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, no 1, article id 8966Article in journal (Refereed) Published
Abstract [en]

Industrially scalable methods for the production of graphene and other nanographites are needed to achieve cost-efficient commercial products. At present, there are several available routes for the production of these materials but few allow large-scale manufacturing and environmentally friendly low-cost solvents are rarely used. We have previously demonstrated a scalable and low-cost industrial route to produce nanographites by tube-shearing in water suspensions. However, for a deeper understanding of the exfoliation mechanism, how and where the actual exfoliation occurs must be known. This study investigates the effect of shear zone geometry, straight and helical coil tubes, on this system based on both numerical simulation and experimental data. The results show that the helical coil tube achieves a more efficient exfoliation with smaller and thinner flakes than the straight version. Furthermore, only the local wall shear stress in the turbulent flow is sufficient for exfoliation since the laminar flow contribution is well below the needed range, indicating that exfoliation occurs at the tube walls. This explains the exfoliation mechanism of water-based tube-shear exfoliation, which is needed to achieve scaling to industrial levels of few-layer graphene with known and consequent quality.

National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-36084 (URN)10.1038/s41598-019-45133-y (DOI)2-s2.0-85067662886 (Scopus ID)
Available from: 2019-05-06 Created: 2019-05-06 Last updated: 2019-07-10Bibliographically approved
Blomquist, N. (2019). Large-Scale Graphene Production for Environmentally Friendly and Low-Cost Energy Storage: Production, Coating, and Applications. (Doctoral dissertation). Sundsvall: Mid Sweden University
Open this publication in new window or tab >>Large-Scale Graphene Production for Environmentally Friendly and Low-Cost Energy Storage: Production, Coating, and Applications
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

There is great demand for energy-efficient, environmentally sustainable, and cost-effective electrical energy storage devices. One important aspect of this demand is the need for automotive electrification to achieve more energy-efficient transportation at a reasonable cost, thus supporting a fossil-fuel free society. Another important aspect is the requirement for energy storage in the growing field of renewable energy production from wind and solar sources, which generates an irregular supply of electricity due to weather conditions.Much of the research in this area has been conducted in the field of battery technology with impressive results, but the need for rapid storage devices such as supercapacitors is growing. Due to the excellent ability of supercapacitors to handle short peak power pulses with high efficiency along with their long lifetime and superior cyclability, their implementations range from small consumer electronics to electric vehicles and stationary grid applications. Supercapacitors also have the potential to complement batteries to improve pulse efficiency and lifetime of the system, however, the cost of supercapacitors is a significant issue for large-scale commercial use, leading to a demand for sustainable, low-cost materials and simplified manufacturing processes. An important way to address this need is to develop a cost-efficient and environment-friendly large-scale process to produce highly conductive nanographites, such as graphene and graphite nanoplatelets, along with methods to manufacture low-cost electrodes from large area coating.

In this thesis, I present a novel process to mechanically exfoliate industrial quantities of nanographite from graphite in an aqueous environment with low energy consumption and at controlled shear conditions. The process is based on hydrodynamic tube-shearing and can produce both multilayer graphene and nanometer-thick and micrometer-wide flakes of nanographite. I also describe the production of highly conductive and robust carbon composites based on the addition of nanocellulose during production; these are suitable as electrodes in applications ranging from supercapacitors and batteries to printed electronics and solar cells.Furthermore I demonstrate a scalable route for roll-to-roll coating of the nanographite-nanocellulose electrode material and propose a novel aqueous, low-cost, and metal-free supercapacitor concept with graphite foil functioning as the current collector. The supercapacitors possessedmore than half the specific capacitance of commercial units but achieved a material cost reduction of more than 90 %, demonstrating anenvironment-friendly, low-cost alternative to conventional supercapacitors.

Abstract [sv]

Det finns en stor efterfrågan av energieffektiva, miljömässigt hållbara och kostnadseffektiva elektriska energilagringsenheter. En viktig del av denna efterfrågan kommer från fordonsindustrins behov av elektrifiering, för att uppnå mer energieffektiva fordon till en rimlig kostnad och på så vis bidra till ett fossilfritt samhälle. En annan viktig del är behovet av energilagring för den ökande andelen förnybar energiproduktion från sol- och vindkraft, som genererar elektrisk energi oregelbundet utifrån gällande väderförhållanden. Det pågår mycket forskning inom området för batteriteknik och framgångarna är imponerande men behovet växer också snabbt för snabba energilagrare som exempelvis superkondensatorer. Tack vare superkondensatorernas utmärkta prestanda, när det gäller att hantera korta effektpulser med hög effektivitet tillsammans med dess långa livslängd och överlägsna cyklingsbarhet, sträcker sig applikationerna frånhemelektronik till elfordon och elnätsapplikationer. Superkondensatorer har också potential att komplettera batterier för att uppnå energilagringssystem med ökad pulseffiktivitet och livslängd. Nackdelen är superkondensatorns kostnad, som markant hämmar storskaligkommersialisering, och således kräver utveckling av hållbara och kostnadseffektiva material tillsammans med förenklade tillverkningsmetoder. Ett sätt att lösa detta på, är att utveckla en kostnadseffektiv och miljövänlig process i stor skala för att framställa nanografit med hög elektrisk ledningsförmåga, så som grafén och grafitnanoflak.

I denna avhandling presenterar jag en ny process för att mekaniskt exfoliera grafit till nanografit storskaligt i vattendispersion, med en låg energiåtgång och under kontrollerade skjuvförhållanden. Processen är baserad på hydrodynamisk skjuvning i rör och denproducerar grafen samt nanometertunna och mikrometerbreda flak av nanografit. Som tillägg visar jag också hur robusta kompositer kan tillverkas med hög ledningsförmåga genom att tillsätta nanofibrillerad cellulosa under processen. Dessa kompositer är lämpliga som elektroder i applikationer från superkondensatorer och batterier till tryckt elektronik och solceller.Jag demonstrerar också en skalbar metod för rulle-till-rulle bestrykning av nanografit-nanocellulosa-materialet samt föreslår ett nytt lågkostnads-koncept för metall-fria superkondensatorer med vattenbaserad elektrolyt, där vi använt grafitfolie som kontakt. Superkondensatorerna hade mer än halva den specifika kapacitansen jämfört med kommersiella enheter men materialkostnaden var 90 % lägre, vilket visar på ett miljövänligt lågkostnadsalternativ till konventionella superkondensatorer.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2019. p. 90
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 297
Keywords
Graphene, Energy storage, Supercapacitors, EDLC
National Category
Other Physics Topics
Identifiers
urn:nbn:se:miun:diva-36068 (URN)978-91-88527-99-8 (ISBN)
Public defence
2019-05-10, O102, Holmgatan 10, Sundsvall, 10:15 (English)
Opponent
Supervisors
Note

Vid tidpunkten för disputationen var följande delarbeten opublicerade: delarbete 3 (inskickat), delarbete 5 (manuskript).

At the time of the doctoral defence the following papers were unpublished: paper 3 (submitted), paper 5 (manuscript).

Available from: 2019-05-06 Created: 2019-05-02 Last updated: 2019-05-06Bibliographically approved
Zhang, R., Hummelgård, M., Örtegren, J., Yang, Y., Andersson, H., Balliu, E., . . . Olin, H. (2019). Sensing body motions based on charges generated on the body. Nano Energy, 63, Article ID 103842.
Open this publication in new window or tab >>Sensing body motions based on charges generated on the body
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2019 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 63, article id 103842Article in journal (Refereed) Published
Abstract [en]

The sensing of body motions is of great importance in areas such as healthcare, rehabilitation, and human-computer interactions. Different methods have been developed based on visual or electrical signals. However, such signals are acquired by external devices and are not intrinsic signals that are created on the body. Here, we report a new universal body motion sensor (UBS) to detect motions based on the intrinsic contact electrification (CE) of the skin or electrical induction (EI) of the body. The CE or EI generates charges on the body, leading to potential differences between the body and ground that can be measured to identify different body motions, such as motions of the head, arms, fingers, waist, legs, feet and toes. Proof-of-concept experiments have demonstrated that the UBS can be used to monitor the conditions of people with Parkinson's disease (PD) and to quantitatively monitor the recovery of those with a leg injury, suggesting great potential for healthcare applications.

Keywords
Body motions, Sensors, Charges, Contact electrification, Electrical induction, Healthcare
Identifiers
urn:nbn:se:miun:diva-36826 (URN)10.1016/j.nanoen.2019.06.038 (DOI)000480422400034 ()
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-09-02Bibliographically approved
Rastabi, S. A., Mamoory, R. S., Dabir, F., Blomquist, N., Phadatare, M. R. & Olin, H. (2019). Synthesis of NiMoO4/3D-rGO Nanocomposite in Alkaline Environments for Supercapacitor Electrodes. Crystals, 9(1), Article ID 31.
Open this publication in new window or tab >>Synthesis of NiMoO4/3D-rGO Nanocomposite in Alkaline Environments for Supercapacitor Electrodes
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2019 (English)In: Crystals, ISSN 2073-4352, Vol. 9, no 1, article id 31Article in journal (Refereed) Published
Abstract [en]

Although Graphene oxide (GO)-based materials is known as a favorable candidate for supercapacitors, its conductivity needs to be increased. Therefore, this study aimed to investigate the performance of GO-based supercapicitor with new methods. In this work, an ammonia solution has been used to remove the oxygen functional groups of GO. In addition, a facile precipitation method was performed to synthesis a NiMoO4/3D-rGO electrode with purpose of using synergistic effects of rGO conductivity properties as well as NiMoO4 pseudocapacitive behavior. The phase structure, chemical bands and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), Raman spectroscopy, and field emission secondary electron microscopy (FE-SEM). The electrochemical results showed that the NiMoO4/3D-rGO(II) electrode, where ammonia has been used during the synthesis, has a capacitive performance of 932 Fg(-1). This is higher capacitance than NiMoO4/3D-rGO(I) without using ammonia. Furthermore, the NiMoO4/3D-rGO(II) electrode exhibited a power density of up to 17.5 kW kg(-1) and an energy density of 32.36 Wh kg(-1). These results showed that ammonia addition has increased the conductivity of rGO sheets, and thus it can be suggested as a new technique to improve the capacitance.

Keywords
renewable energy systems, pseudocapacitive behavior, electrochemical results, ammonia, oxygen groups
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-35806 (URN)10.3390/cryst9010031 (DOI)000458578100031 ()
Available from: 2019-03-19 Created: 2019-03-19 Last updated: 2019-03-19Bibliographically approved
Andres, B., Dahlström, C., Blomquist, N., Norgren, M. & Olin, H. (2018). Cellulose binders for electric double-layer capacitor electrodes: The influence of cellulose quality on electrical properties. Materials & design, 141, 342-349
Open this publication in new window or tab >>Cellulose binders for electric double-layer capacitor electrodes: The influence of cellulose quality on electrical properties
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2018 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 141, p. 342-349Article in journal (Refereed) Published
Abstract [en]

Cellulose derivatives are widely used as binders and dispersing agents in different applications. Binders composed of cellulose are an environmentally friendly alternative to oil-based polymer binding agents. Previously, we reported the use of cellulose nanofibers (CNFs) as binders in electrodes for electric double-layer capacitors (EDLCs). In addition to good mechanical stability, we demonstrated that CNFs enhanced the electrical performance of the electrodes. However, cellulose fibers can cover a broad range of length scales, and the quality requirements from an electrode perspective have not been thoroughly investigated. To evaluate the influence of fiber quality on electrode properties, we tested seven samples with different fiber dimensions that are based on the same kraft pulp. To capture the length scale from fibers to nanofibrils, we evaluated the performance of the untreated kraft pulp, refined fibers, microfibrillated cellulose (MFC) and CNFs. Electrodes with kraft pulp or refined fibers showed the lowest electrical resistivity. The specific capacitances of all EDLCs were surprisingly similar, but slightly lower for the EDLC with CNFs. The same electrode sample with CNFs also showed a slightly higher equivalent series resistance (ESR), compared to those of the other EDLCs. Graphite dispersions with MFC showed the best dispersion stability. 

Keywords
Cellulose, Electric double-layer capacitor, Graphite, Nanocellulose, Nanocomposite, Supercapacitor
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-32766 (URN)10.1016/j.matdes.2017.12.041 (DOI)000424945300031 ()2-s2.0-85040002856 (Scopus ID)
Available from: 2018-01-30 Created: 2018-01-30 Last updated: 2018-07-19Bibliographically approved
Blomquist, N., Wells, T., Andres, B., Bäckström, J., Forsberg, S. & Olin, H. (2017). Metal-free supercapacitor with aqueous electrolyte and low-cost carbon materials. Scientific Reports, 7, Article ID 39836.
Open this publication in new window or tab >>Metal-free supercapacitor with aqueous electrolyte and low-cost carbon materials
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 39836Article in journal (Refereed) Published
Abstract [en]

Electric double-layer capacitors (EDLCs) or supercapacitors (SCs) are fast energy storage devices with high pulse efficiency and superior cyclability, which makes them useful in various applications including electronics, vehicles and grids. Aqueous SCs are considered to be more environmentally friendly than those based on organic electrolytes. Because of the corrosive nature of the aqueous environment, however, expensive electrochemically stable materials are needed for the current collectors and electrodes in aqueous SCs. This results in high costs for a given energy-storage capacity. To address this, we developed a novel low-cost aqueous SC using graphite foil as the current collector and a mix of graphene, nanographite, simple water-purification carbons and nanocellulose as electrodes. The electrodes were coated directly onto the graphite foil by using casting frames and the SCs were assembled in a pouch cell design. With this approach, we achieved a material cost reduction of greater than 90% while maintaining approximately one-half of the specific capacitance of a commercial unit, thus demonstrating that the proposed SC can be an environmentally friendly, low-cost alternative to conventional SCs.

Place, publisher, year, edition, pages
Nature Publishing Group, 2017
Keywords
Supercapacitor, EDLC, Graphene, Graphite, Nanoparticles
National Category
Composite Science and Engineering Condensed Matter Physics
Identifiers
urn:nbn:se:miun:diva-29827 (URN)10.1038/srep39836 (DOI)000391182900001 ()2-s2.0-85008701942 (Scopus ID)
Funder
Swedish Energy Agency
Note

Published online:05 January 2017

Available from: 2017-01-06 Created: 2017-01-06 Last updated: 2019-05-02Bibliographically approved
Andres, B., Engström, A.-C., Blomquist, N., Forsberg, S., Dahlström, C. & Olin, H. (2016). Electrode Mass Balancing as an Inexpensive and Simple Method to Increase the Capacitance of Electric Double-Layer Capacitors. PLoS ONE, 11(9), 1-12, Article ID e0163146.
Open this publication in new window or tab >>Electrode Mass Balancing as an Inexpensive and Simple Method to Increase the Capacitance of Electric Double-Layer Capacitors
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2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 9, p. 1-12, article id e0163146Article in journal (Refereed) Published
Abstract [en]

Symmetric electric double-layer capacitors (EDLCs) have equal masses of the same active material in both electrodes. However, having equal electrode masses may prevent the EDLC to have the largest possible specific capacitance if the sizes of the hydrated anions and cations in the electrolyte differ because the electrodes and the electrolyte may not be completely utilized. Here we demonstrate how this issue can be resolved by mass balancing. If the electrode masses are adjusted according to the size of the ions, one can easily increase an EDLC's specific capacitance. To that end, we performed galvanostatic cycling to measure the capacitances of symmetric EDLCs with different electrode mass ratios using four aqueous electrolytes-Na2SO4, H2SO4, NaOH, and KOH (all with a concentration of 1 M)-and compared these to the theoretical optimal electrode mass ratio that we calculated using the sizes of the hydrated ions. Both the theoretical and experimental values revealed lower-than-1 optimal electrode ratios for all electrolytes except KOH. The largest increase in capacitance was obtained for EDLCs with NaOH as electrolyte. Specifically, we demonstrate an increase of the specific capacitance by 8.6% by adjusting the electrode mass ratio from 1 to 0.86. Our findings demonstrate that electrode mass balancing is a simple and inexpensive method to increase the capacitance of EDLCs. Furthermore, our results imply that one can reduce the amount of unused material in EDLCs and thus decrease their weight, volume and cost.

Keywords
Mass balancing, capacitance, electric double layer capacitor, EDLC, electrode, electrolyte, electrode mass ratio, ion size ratio
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:miun:diva-29083 (URN)10.1371/journal.pone.0163146 (DOI)000383893200073 ()2-s2.0-84992186879 (Scopus ID)
Available from: 2016-10-10 Created: 2016-10-10 Last updated: 2017-11-30Bibliographically approved
Blomquist, N. (2016). Large-Scale Nanographite Exfoliation for Low-Cost Metal-Free Supercapacitors. (Licentiate dissertation). Sundsvall: Mid Sweden University
Open this publication in new window or tab >>Large-Scale Nanographite Exfoliation for Low-Cost Metal-Free Supercapacitors
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2016. p. 34
Series
Mid Sweden University licentiate thesis, ISSN 1652-8948 ; 125
National Category
Physical Sciences
Identifiers
urn:nbn:se:miun:diva-29720 (URN)978-91-88025-74-6 (ISBN)
Presentation
2016-08-31, O102, Sundsvall, 10:30 (English)
Supervisors
Note

Vid tidpunkten för framläggningen av avhandlingen var följande delarbeten opublicerade: delarbete 2 inskickat.

At the time of the defence the following papers were unpublished: paper 2 submitted.

Available from: 2016-12-21 Created: 2016-12-21 Last updated: 2016-12-21Bibliographically approved
Blomquist, N., Engström, A.-C., Hummelgård, M., Andres, B., Forsberg, S. & Olin, H. (2016). Large-Scale Production of Nanographite by Tube-Shear Exfoliation in Water. PLoS ONE, 11(4), Article ID e0154686.
Open this publication in new window or tab >>Large-Scale Production of Nanographite by Tube-Shear Exfoliation in Water
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2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 4, article id e0154686Article in journal (Refereed) Published
Abstract [en]

The number of applications based on graphene, few-layer graphene, and nanographite is rapidly increasing. A large-scale process for production of these materials is critically needed to achieve cost-effective commercial products. Here, we present a novel process to mechanically exfoliate industrial quantities of nanographite from graphite in an aqueous environment with low energy consumption and at controlled shear conditions. This process, based on hydrodynamic tube shearing, produced nanometer-thick and micrometer-wide flakes of nanographite with a production rate exceeding 500 gh-1 with an energy consumption about 10 Whg-1. In addition, to facilitate large-area coating, we show that the nanographite can be mixed with nanofibrillated cellulose in the process to form highly conductive, robust and environmentally friendly composites. This composite has a sheet resistance below 1.75 Ω/sq and an electrical resistivity of 1.39×10-4 Ωm and may find use in several applications, from supercapacitors and batteries to printed electronics and solar cells. A batch of 100 liter was processed in less than 4 hours. The design of the process allow scaling to even larger volumes and the low energy consumption indicates a low-cost process.

Place, publisher, year, edition, pages
Nicklas Blomquist, 2016
Keywords
Nano-graphite, Graphite, Graphene, Nanomaterials, Composite materials
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-27600 (URN)10.1371/journal.pone.0154686 (DOI)000375212600060 ()2-s2.0-84966389426 (Scopus ID)
Projects
KEPS
Funder
Swedish Energy Agency
Available from: 2016-05-09 Created: 2016-05-09 Last updated: 2019-05-02Bibliographically approved
Andres, B., Dahlström, C., Engström, A.-C., Forsberg, S., Blomquist, N. & Olin, H. (2015). Cellulose-based binder systems for electrochemical electrodes. In: : . Paper presented at 2015 E-MRS Spring Meeting.
Open this publication in new window or tab >>Cellulose-based binder systems for electrochemical electrodes
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2015 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:miun:diva-26560 (URN)
Conference
2015 E-MRS Spring Meeting
Available from: 2015-12-16 Created: 2015-12-16 Last updated: 2015-12-18Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4303-2585

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