Structural composite supercapacitor

{{Short description|Multifunctional material for energy storage}}

{{Multiple issues|

{{Technical|date=May 2022}}

{{Tone|date=May 2022}}

{{Context|date=May 2022}}

{{Orphan|date=February 2024}}

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Structural composite supercapacitors are multifunctional materials that can both bear mechanical load and store electrical energy.{{Cite patent|country=US|number=8659874|title=Energy storage device|pubdate=2014-02-25|inventor1-last=Shaffer|inventor1-first=Milo|inventor2-last=Greenhalgh|inventor2-first=Emile|inventor3-last=Bismarck|inventor3-first=Alexander|assign1=Imperial Innovations Ltd.|inventor4-last=Curtis|inventor4-first=Paul T.}} That when combined with structural batteries, could potentially enable an overall weight reduction of electric vehicles.

Typically, structural composite supercapacitors are based on the design of carbon fiber reinforced polymers.{{Cite journal|last1=Xu|first1=Yanfang|last2=Lu|first2=Weibang|last3=Xu|first3=Guangbiao|last4=Chou|first4=Tsu-Wei|date=2021-03-01|title=Structural supercapacitor composites: A review|url=https://www.sciencedirect.com/science/article/pii/S0266353820324301|journal=Composites Science and Technology|language=en|volume=204|pages=108636|doi=10.1016/j.compscitech.2020.108636|s2cid=233855113|issn=0266-3538|url-access=subscription}} Carbon fibers act as mechanical reinforcement, current collectors, and eventually electrodes.

The matrix of a Structural composite supercapacitor is a polymer electrolyte that transfers load via shear mechanisms between the carbon fibers and has a reasonable ionic conductivity.{{Cite journal|last1=Nguyen|first1=Phuong-Anh T.|last2=Snyder|first2=James|date=2008-10-03|title=Multifunctional Properties of Structural Gel Electrolytes|url=https://doi.org/10.1149/1.2992495|journal=ECS Transactions|language=en|volume=11|issue=32|pages=73–83|doi=10.1149/1.2992495|bibcode=2008ECSTr..11F..73N|s2cid=98505434|issn=1938-5862|url-access=subscription}}

In a supercapacitor, the specific capacitance is proportional to the exact surface area of the electrodes.{{Cite journal|last=Burke|first=Andrew|date=November 2000|title=Ultracapacitors: why, how, and where is the technology|url=https://linkinghub.elsevier.com/retrieve/pii/S0378775300004857|journal=Journal of Power Sources|language=en|volume=91|issue=1|pages=37–50|doi=10.1016/S0378-7753(00)00485-7|bibcode=2000JPS....91...37B|s2cid=12394674 }} Structural carbon fibers usually have low specific surface area, and is therefore necessary to modify their surface to enable sufficient energy storage ability.{{Cite journal|last1=Snyder|first1=James F.|last2=Wong|first2=Emma L.|last3=Hubbard|first3=Clifford W.|date=2009|title=Evaluation of Commercially Available Carbon Fibers, Fabrics, and Papers for Potential Use in Multifunctional Energy Storage Applications|url=https://iopscience.iop.org/article/10.1149/1.3065070|journal=Journal of the Electrochemical Society|language=en|volume=156|issue=3|pages=A215|doi=10.1149/1.3065070|bibcode=2009JElS..156A.215S|doi-access=free|archive-date=2023-04-07|access-date=2022-02-15|archive-url=https://web.archive.org/web/20230407111408/https://iopscience.iop.org/article/10.1149/1.3065070|url-status=live}} To increase the surface area of the structural electrodes, several methods have been employed, mainly consisting in the modification of the surface of the carbon fiber itself, or by coating the carbon fiber through a material which covers its entire surface area.

Physical and chemical activation of the carbon fibers have increased their specific surface area by two orders of magnitude without damaging their mechanical properties, but have limited energy storage ability when combined with a structural polymer electrolyte.{{Cite journal|last1=Qian|first1=Hui|last2=Diao|first2=Hele|last3=Shirshova|first3=Natasha|last4=Greenhalgh|first4=Emile S.|last5=Steinke|first5=Joachim G.H.|last6=Shaffer|first6=Milo S.P.|last7=Bismarck|first7=Alexander|date=April 2013|title=Activation of structural carbon fibres for potential applications in multifunctional structural supercapacitors|url=https://linkinghub.elsevier.com/retrieve/pii/S0021979712013902|journal=Journal of Colloid and Interface Science|language=en|volume=395|pages=241–248|doi=10.1016/j.jcis.2012.12.015|pmid=23312580|bibcode=2013JCIS..395..241Q|archive-date=2022-06-15|access-date=2022-02-15|archive-url=https://web.archive.org/web/20220615150711/https://linkinghub.elsevier.com/retrieve/pii/S0021979712013902|url-status=live|url-access=subscription}} Coating carbon fibers with carbon nanotubes,{{Cite journal|last1=Shirshova|first1=Natasha|last2=Qian|first2=Hui|last3=Houllé|first3=Matthieu|last4=Steinke|first4=Joachim H. G.|last5=Kucernak|first5=Anthony R. J.|last6=Fontana|first6=Quentin P. V.|last7=Greenhalgh|first7=Emile S.|last8=Bismarck|first8=Alexander|last9=Shaffer|first9=Milo S. P.|date=2014|title=Multifunctional structural energy storage composite supercapacitors|url=http://xlink.rsc.org/?DOI=C4FD00055B|journal=Faraday Discuss.|language=en|volume=172|pages=81–103|doi=10.1039/C4FD00055B|pmid=25427162|bibcode=2014FaDi..172...81S|issn=1359-6640|hdl=10044/1/19256|hdl-access=free}} carbon aerogel,{{Cite journal|last1=Qi|first1=Guocheng|last2=Nguyen|first2=Sang|last3=Anthony|first3=David B|last4=Kucernak|first4=Anthony R J|last5=Shaffer|first5=Milo S P|last6=Greenhalgh|first6=Emile S|date=2021-09-01|title=The influence of fabrication parameters on the electrochemical performance of multifunctional structural supercapacitors|url=https://iopscience.iop.org/article/10.1088/2399-7532/ac1ea6|journal=Multifunctional Materials|volume=4|issue=3|pages=034001|doi=10.1088/2399-7532/ac1ea6|bibcode=2021MuMat...4c4001Q|s2cid=237369927|issn=2399-7532|hdl=10044/1/97587|hdl-access=free}} or graphene nanoplatelets{{Cite journal|last1=Hubert|first1=Olivier|last2=Todorovic|first2=Nikola|last3=Bismarck|first3=Alexander|date=January 2022|title=Towards separator-free structural composite supercapacitors|journal=Composites Science and Technology|language=en|volume=217|pages=109126|doi=10.1016/j.compscitech.2021.109126|s2cid=243485329|doi-access=free}} allowed for higher energy densities.