| Full text | |
| Author(s): |
Galiote, Nelson A.
[1]
;
de Azevedo, Dayse C.
[2]
;
Oliveira, Jr., Osvaldo N.
[2]
;
Huguenin, Fritz
[1]
Total Authors: 4
|
| Affiliation: | [1] Univ Sao Paulo, Dept Quim, Fac Filosofia Ciencias & Letras Ribeirao Preto, BR-14040901 Ribeirao Preto, SP - Brazil
[2] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
Total Affiliations: 2
|
| Document type: | Journal article |
| Source: | Journal of Physical Chemistry C; v. 118, n. 38, p. 21995-22002, SEP 25 2014. |
| Web of Science Citations: | 7 |
| Abstract | |
The high theoretical energy density of lithium-oxygen batteries brings the promise of higher performance than existing batteries, but several technological problems must be addressed before actual applications are made possible. Among the difficulties to be faced is the slow oxygen reduction reaction (ORR), which requires a suitable choice of catalysts and electrolytic solution. This can only be achieved if the kinetics and mechanism of this reaction are known in detail. In this study, we determined the rate constants for each elementary step of ORR for a platinum electrode in 0.1 mol.L-1 LiClO4/1,2-dimethoxyethane (DME), using a kinetic model in the frequency domain. We found that the energy storage capacity of lithium-air batteries can be increased by converting a large amount of lithium superoxide into lithium peroxide during the electrochemical step in comparison with chemical disproportionation. The mechanisms for ORR were supported by data from an electrochemical quartz crystal microbalance (EQCM): ORR could be distinguished from parasitic reactions induced by solvent degradation, and agglomerates of LixO2 (1 <= x <= 2) were adsorbed on the electrode. The rate-limiting step for ORR was the electron transfer to the oxygen molecules strongly adsorbed onto platinum sites, particularly as a large amount of reaction product (Li2O2) adsorbed onto the electrode. Even though Pt sheets are likely to be impracticable for real applications due to their low surface area, they were useful in making it possible to determine the kinetics of ORB. steps. This can now be employed to devise more involved electrodes, such as those containing dispersed Pt nanoparticles. (AU) | |
| FAPESP's process: | 12/21629-1 - Polycyanometalates for mixing entropy batteries |
| Grantee: | Fritz Cavalcante Huguenin |
| Support Opportunities: | Regular Research Grants |
| FAPESP's process: | 11/12668-0 - Nanoparticulate Materials for Lithium-air Batteries |
| Grantee: | Nelson Alexandre Galiote Silva |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 11/21545-0 - Electrocatalysts for Li-air batteries |
| Grantee: | Fritz Cavalcante Huguenin |
| Support Opportunities: | Regular Research Grants |