Magnesium insertion and related structural changes in spinel-type manganese oxides

Robba, Ana (author), Tchernychova, Elena (author), Bitenc, Jan (author), Randon-Vitanova, Anna (author), Dominko, Robert (author)

Commercial LiMn$_2$O$_4$ powder was used as the base material for probing magnesiation, cycling behavior, and structural stability/changes in (Mg$_x$Li$_{1-x}$)Mn$_2$O$_4$ spinel cathodes in aqueous Mg(NO$_3$)$_2$ and non-aqueous Mg(TFSI)$_2$/diglyme and Mg(Mg(HFIP)$_2$ − 2Al(HFIP)$_3$/diglyme electrolytes. Each of the samples was delithiated and, then, magnesiated electrochemically in the corresponding electrolyte. The electrochemical activity of the cathode cycled in aqueous electrolyte showed high reversibility during the oxidation process; however, large polarization and a relatively fast capacity fading were the culprits of the system. Cycling in Mg(TFSI)2/diglyme electrolyte solution resulted in much lower initial specific capacity compared to an aqueous counterpart, as well as a much faster failure. On the other hand, cycling in Mg(HFIP)$_2$ − 2Al(HFIP)$_3$/diglyme electrolyte solution demonstrated excellent cycling performance with very low polarization in the first cycles. The observed voltages for this system were near theoretical values for the Mg insertion. Although the electrochemical measurements suggest reversible magnesiation, detailed structural and analytical STEM investigation revealed the differences in the atomic structure and Mn valence of all three cathode samples upon cycling. The electrolytes’ influence on the structural rearrangement during Mg insertion is discussed for each of the three systems.

• Language: English
• Keywords: spinel, manganese, lithium, magnesium, TEM, electrochemistry
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2021
• Number of pages: 12 str.
• Numbering: Vol. 11, iss. 8, art. 984
• PID: 20.500.12556/RUL-135999
• UDC: 544.1:544.6
• ISSN on article: 2073-4352
• DOI: 10.3390/cryst11080984
• COBISS.SI-ID: 78444291
• Publication date in RUL: 06.04.2022

Record is a part of a journal

• Title: Crystals
• Shortened title: Crystals
• Publisher: MDPI
• ISSN: 2073-4352
• COBISS.SI-ID: 36677893

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 19.08.2021

Secondary language

• Language: Slovenian
• Keywords: spinel, mangan, litij, magnezij, TEM, elektrokemija

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0393
• Name: Napredni materiali za nizkoogljično in trajnostno družbo

• Funder: Other - Other funder or multiple funders
• Funding programme: Honda R&D Europe