Mechanisms of manganese spinels dissolution and capacity fade at high temperature

Tests on the stability of spinels stored at different states of charge were performed. It was found that Mn dissolution took place irreversibly from the charged state with formation of MnF 2, ramsdellite–Li 0.5MnO 2. In the discharged state, the Mn at the surface of the LiMn 2O 4 was in equilibrium...

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Bibliographic Details
Published inJournal of power sources Vol. 97; pp. 377 - 380
Main Authors Aoshima, Takayuki, Okahara, Kenji, Kiyohara, Chikara, Shizuka, Kenji
Format Journal Article Conference Proceeding
LanguageEnglish
Published Lausanne Elsevier B.V 01.07.2001
Elsevier Sequoia
Subjects
Applied sciences
Capacity fade
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
Lithium manganese oxides
Mn dissolution
Storage
Lithium manganese oxides
Storage
Capacity fade
Mn dissolution
Ternary compound
Performance evaluation
Alkali metal Compounds
Transition metal Compounds
Secondary cell
Electrode material
Electric batteries
Intercalation compound
Metal metal oxide batteries
Manganese oxides
Organic electrolyte storage battery
Spinels
Electrodissolution
Lithium oxide
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Summary:Tests on the stability of spinels stored at different states of charge were performed. It was found that Mn dissolution took place irreversibly from the charged state with formation of MnF 2, ramsdellite–Li 0.5MnO 2. In the discharged state, the Mn at the surface of the LiMn 2O 4 was in equilibrium with a soluble species, which leads to an increase in the cathode resistance. It was found that the amount of the dissolved Mn increased with increasing LiPF 6 concentration and that 2 equiv. of PO 2F 2 − were generated. Concurrent formation of carbonate decomposition products, such as CO 2, C 2H 4, EtOH, Et 2O, and AcOEt, suggests that the mechanism of Mn dissolution from the charged state was composed of the following steps: the initial decarboxylation of electrolyte catalyzed by λMnO 2 to give EtOH, followed by reduction of λMnO 2 by EtOH to give acetate and MnO, and then Mn dissolution via MnO bond activation assisted by LiPF 6.
Bibliography:SourceType-Scholarly Journals-2
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ObjectType-Conference Paper-1
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SourceType-Conference Papers & Proceedings-1
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ISSN:0378-7753
1873-2755
DOI:10.1016/S0378-7753(01)00551-1