• Wills, Richard G. A.
• Deepa, Melepurath
• Houx, James Le
• Ojha, Manoranjan
• Mukkabla, Radha
• Kramer, Denis

Abstract

<p>A facile scalable strategy is reported for the synthesis of a hybrid of lithium titanate (Li₄Ti₅O₁₂or 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⁻¹at 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.</p>

Topics

• nanoparticle
• density
• impedance spectroscopy
• Carbon
• energy density
• nanotube
• mass spectrometry
• Lithium
• electrical conductivity