Electrochemical Behavior of Electrolytic Manganese Dioxide in Aqueous KOH and LiOH Solutions: A Comparative Study. Issue 3 (9th December 2015)

• Record Type: Journal Article
• Authors: Rus, Eric D.; Moon, Geon Dae; Bai, Jianming; Steingart, Daniel A.; Erdonmez, Can K.
• Is Part Of: Journal of the Electrochemical Society. Volume 163:Issue 3(2016)
• Page Start: A356
• Page End: A363
• Publication Date: 2015-12-09
• Subjects: in situ -- lithium hydroxide -- potassium hydroxide -- ramsdellite -- synchrotron x-ray diffraction; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.1011602jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : As an inexpensive and high capacity oxidant, electrolytic manganese dioxide (γ-MnO2 ) is of interest as a cathode for secondary aqueous batteries. Electrochemical behavior of γ-MnO2 was characterized in aqueous 5.0 M KOH and LiOH solutions, and found to depend strongly upon cation identity. In LiOH and mixed LiOH / KOH solutions, Li-ion intercalation appeared to operate in competition with proton intercalation, being favored at higher [Li + ] and, for mixed electrolytes, lower sweep rates. Electrochemical and in situ X-ray diffraction data indicated that γ-MnO2 underwent a chemically irreversible transformation upon the first reduction in LiOH solution, while in KOH solution, structure was largely unchanged after the first cycle. These experiments with γ-MnO2 as well as with a closely-related, ramsdellite-like sample, suggest that depending on sample morphology/rate capability, the irreversible process proceeds either through a solid-solution reaction or a two-phase reaction followed by a solid-solution reaction. While discharge capacity and capacity retention during galvanostatic cycling of γ-MnO2 were worse in LiOH than in KOH solution, some improvement was noted in a mixed LiOH/KOH solution.