Can polyoxometalates enhance the capacitance and energy density of activated carbon in organic electrolyte supercapacitors?
Zhu, Jun-Jie (Institut Català de Nanociència i Nanotecnologia)
Benages Vilau, Raúl (Institut Català de Nanociència i Nanotecnologia)
Gómez-Romero, Pedro 1959- (Institut Català de Nanociència i Nanotecnologia)

Data:	2020
Resum:	Polyoxometalates (POMs) have been shown to work as faradaic additives to activated carbon (AC) in acidic aqueous electrolytes. Yet, their use in organic media allows not only for added capacity but also higher voltage. Here we show that the tetraethylammonium derivative of phosphotungstate [PWO] (PW12) can be homogeneously distributed throughout the pores of activated carbon (AC) in organic solvents such as N,N'-dimethylformamide (DMF) and demonstrate the use of this hybrid electrode material in an organic electrolyte (1 M TEABF4 in acetonitrile) supercapacitor. Our results show the efficient electroactivity of the PW12 cluster even in the absence of protons, providing a higher voltage than aqueous electrolytes and fast and reversible redox activity. The hybrid material shows a combination of double-layer (AC) and redox (PW12) capacities leading to an increase (36%) in volumetric capacitance with respect to pristine AC in the same organic electrolyte (1 M TEABF4 in acetonitrile). Remarkably, we were able to quantify this increase as coming predominantly from non-diffusion-limited processes thanks to the utterly dispersed nature of POMs. Moreover, the hybrid material delivers a good rate capability and excellent cycle stability (93% retention of the initial capacitance after 10,000 cycles). This study has a profound significance on improving capacitance of carbon-based materials in organic electrolytes.
Ajuts:	Ministerio de Ciencia e Innovación RTI2018-099826-B-I00 Ministerio de Economía y Competitividad SEV-2017-0706 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-00870
Nota:	ICN2 is funded by the CERCA programme / Generalitat de Catalunya. J.J Z. acknowledges his scholarship (No. 201806370211) under China Scholarship Council. This work has been carried out within the framework of doctoral program (PhD) of Material Science (Department of Physics) of Universitat Autònoma de Barcelona (UAB).
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió sotmesa a revisió
Matèria:	Supercapacitor ; Polyoxometalate ; Organic electrolyte ; Hybrid electrode
Publicat a:	Electrochimica acta, Vol. 362 (Dec. 2020) , art. 137007, ISSN 1873-3859

DOI: 10.1016/j.electacta.2020.137007

Preprint 33 p, 2.2 MB

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