Lithium titanate/pyrenecarboxylic acid decorated carbon nanotubes hybrid - Alginate gel supercapacitor

Publication date
2019-06-20
Document type
Research article
Author
Ojha, Manoranjan
Le Houx, James
Mukkabla, Radha
Wills, Richard George Andrew
Deepa, Melepurath
Organisational unit
Energy Technology Research Group, Faculty of Engineering and Physical Sciences, University of Southampton, United Kingdom
DOI
URI
ISSN
Series or journal
Electrochimica Acta
Periodical volume
309
Periodical issue
20 June 2019
First page
253
Last page
263
Peer-reviewed
✅
Part of the university bibliography
Nein
Keyword
Capacitance
Carbon nanotubes
Energy density
Lithium titanate
Supercapacitor
Abstract
A facile scalable strategy is reported for the synthesis of a hybrid of lithium titanate (Li 4 Ti 5 O 12 or LTO)and 1-pyrenecarboxylic acid decorated multiwalled carbon nanotubes (PCA@CNTs). LTO platelets comprising of quasi-spherical nanoparticles afford short diffusion paths for electrolyte ions. PCA@CNTs, enhance the electrical conductivity of the nearly insulating LTO by 3 orders of magnitude, thus maximizing the ion-uptake capability of the hybrid. Symmetric and asymmetric supercapacitors with the LTO/PCA@CNTs hybrid supported over Ni foam substrates are assembled with a novel Li + conducting alginate gel, in air without any inert conditions that are typically used for all LTO based devices. The gel shows an average ionic conductivity of ∼8.4 mS cm −1 at room temperature, and is found to be electrochemically stable over a wide operational voltage window of ∼2.5 V. Benefitting from the synergy of electrical double layer (EDL)storage afforded by PCA@CNTs, ion-storage by LTO through a redox reaction and EDL, and the ease ion-movement across the cell due to the open architecture of CNTs, the asymmetric LTO/PCA@CNTs hybrid cell outperforms the symmetric cells by a large margin. The best areal specific capacitance (SC), volumetric SC and energy density are ∼54 mF cm −2 , ∼4.3 F cm −3 (at 0.5 mA cm −2 )and ∼3.7 mWh cm −3 (at a power density of 49.6 mW cm −3 )significantly enhanced for the asymmetric LTO/PCA@CNTs hybrid cell, compared to the symmetric- PCA@CNTs and hybrid cells. The design is simple to implement and can serve as a prototype to develop a range of yet unexplored LTO/carbon nanomaterial based supercapacitors.
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