High Lithium Ion Electroinsertion Rate into Self-Assembled Films Formed from TiO2

Author(s)

Gomes, Wellington J. A. S. ^[1] ; Araujo, Diogenes M. ^[1] ; Carvalho, Antonio J. F. ^[2] ; Campana-Filho, Sergio P. ^[3] ; Huguenin, Fritz ^[1]

Affiliation

^[1] Univ Sao Paulo, Dept Quim, Fac Filosofia Ciencias & Letras Ribeirao Preto, BR-14040901 Ribeirao Preto, SP - Brazil

^[2] Univ Sao Paulo, Dept Mat Engn, Escola Engn Sao Carlos, BR-13566590 Sao Carlos, SP - Brazil

^[3] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. 117, n. 33, p. 16774-16782, AUG 22 2013.
• Web of Science Citations: 5

Abstract

We prepared self-assembled materials consisting of TiO2 nanoparticles, N,O-carboxymethylchitosan (NOCMCh), and poly(ethylene oxide) (PEO) by the layer-by-layer (LbL) technique, aiming to employ them as modified electrodes under high lithium ion electroinsertion rate. Electrostatic interaction between the components promoted growth of visually uniform TiO2/NOCMCh films with highly controlled thickness. We used NOCMCh to produce a polymeric mixture with PEO to incorporate the polyether into the self-assembled structure during the preparation of the LbL TiO2/NOCMCh/PEO films. Scanning electron microscopy (SEM) and contact angle measurements between the electrolytic solution and the thin films surface suggested that the polymers affected the mean size of the aggregates and the permeation of the electrolytic solution into the host matrix, leading to greater electrolytic connection between the TiO2 sites. Chronopotentiometric curves and the differential capacities recorded as a function of the potential under several applied current densities indicated higher charge capacity and absorbance changes (Delta A) for the TiO2/NOCMCh/PEO electrode. We employed the potentiostatic intermittent titration technique (PITT) to determine the chemical diffusion coefficient (D-c) associated with electron and lithium ion diffusion in the host matrices. To investigate the independent motion of these charge carriers in the absence of an internal electrical field, we also obtained the Wagner factor (W) and the lithium (D-Li) and electron (D-e) self-diffusion coefficients. Spectroelectrochemical measurements also indicated higher coloration front rate due to lithium ion transport in the TiO2/NOCMCh/PEO electrodes. The electrochemical impedance spectroscopy (EIS) measurements suggested trapping effects and anomalous diffusion, which contributed to a better understanding of the role that polymeric components play in charge transport within the self-assembled materials under high electroinsertion rate. (AU)

• FAPESP's process: 11/21545-0 - Electrocatalysts for Li-air batteries
• Grantee: Fritz Cavalcante Huguenin
• Support Opportunities: Regular Research Grants
• FAPESP's process: 09/14181-1 - Lithium ion electro-insertion into nanocomposites formed from metal oxides
• Grantee: Fritz Cavalcante Huguenin
• Support Opportunities: Regular Research Grants