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Li4Ti5O12 flexible, lightweight electrodes based on cellulose nanofibrils as binder and carbon fibers as current collectors for Li-ion batteries
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
2017 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 39, p. 140-150Article in journal (Refereed) Published
Abstract [en]

TEMPO oxidized cellulose nanofibrils (TOCNF) were used as binder material to prepare bendable Li4Ti5O12 (LTO) electrodes. Carbon fiber (CF) layers were integrated as current collectors to enhance the mechanical properties and to increase the specific energy of the electrodes. These electrodes combined with CF current collectors (LTO/CF) show good electrochemical properties and are flexible, sustainable, mechanical and chemical stable, lightweight and produced by a water-based easy filtration process. An increase of the active material weight (LTO) from around 19% to 71% of the electrode and current collector combined weight is demonstrated with CF compared with a copper current collector. Additionally, preparation of the current collector material is non-expensive, quick and easy compared to that of carbon nanotube or graphene. To test the flexible battery application, 4000 times repeated bending was carried out on both the LTO electrodes and the LTO/CF electrodes. This had no significant effect on the morphology, mechanical and electrochemical properties of neither the LTO nor the LTO/CF electrodes. Addition of the CF layer improves the mechanical properties and specific capacity of the LTO-electrode. A thicker LTO electrode with only 2 wt% TOCNF is demonstrated which is promising for thicker electrodes with high energy density. A full cell was assembled with the LTO/CF as negative electrode and LiFePO4 (LFP)/CF as positive, which exhibited a stable cycling performance and good energy density.

Place, publisher, year, edition, pages
Elsevier, 2017. Vol. 39, p. 140-150
Keywords [en]
Carbon fiber current collector, Flexible lithium ion batteries, Li4Ti5O12 electrodes, Lightweight, TEMPO-oxidized CNF, Water-based binder
National Category
Materials Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-212239DOI: 10.1016/j.nanoen.2017.06.043ISI: 000408878200014Scopus ID: 2-s2.0-85021718504OAI: oai:DiVA.org:kth-212239DiVA, id: diva2:1134986
Funder
Knut and Alice Wallenberg FoundationSwedish Energy Agency, 37712-1
Note

QC 20170822

Available from: 2017-08-22 Created: 2017-08-22 Last updated: 2018-05-07Bibliographically approved
In thesis
1. Carbon Fibres for Multifunctional Lithium-Ion Batteries
Open this publication in new window or tab >>Carbon Fibres for Multifunctional Lithium-Ion Batteries
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The transportation industry today faces many challenges because of the rapid movement towards electrification. One major challenge is the weight of the battery, which limits the effectiveness of the vehicles. One of the possible routes to reduce the weight on a system-level is introducing structural batteries, batteries that simultaneously storeenergy and hold a mechanical load. Placing these batteries in a load-bearing part of the structure reduces weight and increases effectiveness on a system level. Carbon fibres are especially suited for structural batteries because of the high performance as reinforcement material in a polymer composite, as well as the ability to insert lithium to function as negative electrodes in batteries.

Another field that has attracted attention the latest years is flexible batteries due to the emerging of flexible displays and wearable electronics. Carbon fibres can be a suitable material in flexible batteries due to the good conductivity, mechanical integrity and ability to forman integrated flexible film with cellulose nanofibrils (CNF) as binder.

This thesis focuses on the usage of carbon fibres in structural and flexible batteries. Lignin based and commercial carbon fibres are evaluated as negative electrodes using a combination of electrochemical methods, material characterization and mechanical testing. Further, the diffusion is characterized using nuclear magnetic resonance spectroscopy, revealing an inequality of axial and radial diffusion in carbon fibres. The carbon fibres with a largely disordered structure show most promise as a negative electrode, with a capacity similar to graphite and having a high coulombic efficiency.

Carbon fibres used as current collectors are evaluated as well, both continuous LiFePO4 coated carbon fibres with electrophoretic deposition for structural positive electrode applications and chopped carbonfibres bounded by CNF as a layer in a flexible electrode. The LiFePO4 coated carbon fibres show promise as a structural electrode with moderatecapacity, high coulombic efficiency, good rate performance and good adhesion between fibres and coating. The flexible electrodes with carbon fibres as current collectors perform well with a high capacity, good rate performance, low weight and high flexibility. The electrodes withstand bending for 4000 times without any performance degradation.

Place, publisher, year, edition, pages
Kungliga tekniska högskolan, 2018. p. 78
National Category
Other Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-227296 (URN)978-91-7729-763-5 (ISBN)
Public defence
2018-05-30, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency, 37712-1
Note

QC 20180507

Available from: 2018-05-07 Created: 2018-05-07 Last updated: 2018-05-07Bibliographically approved

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