Composite cathode with Li2Pc

• Published in: Journal of the Electrochemical Society 2004, Vol.151 (9), p.A1338-A1343
• Main Authors: SCANLON, L. G, LUCENTE, L. R, FELD, W. A, SANDI, G, BALBUENA, P. B, ALONSO, P. R, TURNER, A
• Format: Article
• Language: English
• Subjects: Applied sciences; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1772780

Computational chemistry calculations performed with Gaussian 98 were used to develop an experimental method that facilitates ionic connection between the solid-state electrolyte dilithium phthalocyanine (Li2Pc) and manganese dioxide (MnO2). The planar configuration of the phthalocyanine ring and the fact that the lithium ions are very close to the ring may sterically hinder effective ionic coupling between Li2Pc and any potential cathode. This same argument has been used for understanding the insertion and removal of magnesium from water solutions of deuteroporphyrins. Calculated results show that lithium ions are drawn closer to the phthalocyanine ring upon formation of (Li2Pc)2 via molecular self-assembly when compared to the single-molecule Li2Pc. However, extension of lithium ions above the planar phthalocyanine ring in (Li2Pc)2 can be enhanced through formation of a complex at the axial position above lithium. Calculations show that corannulene at the axial position above lithium forms an asymmetric structure with (Li2Pc)2 and extends lithium further above the ring. To test the theoretical results, an electrically conducting carbon with a curved lattice was used in the fabrication of an all solid-state electrochemical cell with a lithium metal foil anode, Li2Pc electrolyte, and a MnO2 cathode. Slow-scan-rate cyclic voltammograms of a LixMnO2 cathode demonstrate the charging and discharging of cells.