Suppressing Manganese Dissolution from Lithium Manganese Oxide Spinel Cathodes with Single‐Layer Graphene |
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| Authors: | Laila Jaber‐Ansari Kanan P Puntambekar Soo Kim Muratahan Aykol Langli Luo Jinsong Wu Benjamin D Myers Hakim Iddir John T Russell Spencer J Saldaña Rajan Kumar Michael M Thackeray Larry A Curtiss Vinayak P Dravid Chris Wolverton Mark C Hersam |
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| Institution: | 1. Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA;2. NUANCE Center, Northwestern University, Evanston, IL, USA;3. Materials Science Division, Argonne National Laboratory, Argonne, IL, USA;4. Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA;5. Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL, USA;6. Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL, USA;7. Department of Chemistry, Northwestern University, Evanston, IL, USA |
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| Abstract: | Spinel‐structured LiMn2O4 (LMO) is a desirable cathode material for Li‐ion batteries due to its low cost, abundance, and high power capability. However, LMO suffers from limited cycle life that is triggered by manganese dissolution into the electrolyte during electrochemical cycling. Here, it is shown that single‐layer graphene coatings suppress manganese dissolution, thus enhancing the performance and lifetime of LMO cathodes. Relative to lithium cells with uncoated LMO cathodes, cells with graphene‐coated LMO cathodes provide improved capacity retention with enhanced cycling stability. X‐ray photoelectron spectroscopy reveals that graphene coatings inhibit manganese depletion from the LMO surface. Additionally, transmission electron microscopy demonstrates that a stable solid electrolyte interphase is formed on graphene, which screens the LMO from direct contact with the electrolyte. Density functional theory calculations provide two mechanisms for the role of graphene in the suppression of manganese dissolution. First, common defects in single‐layer graphene are found to allow the transport of lithium while concurrently acting as barriers for manganese diffusion. Second, graphene can chemically interact with Mn3+ at the LMO electrode surface, promoting an oxidation state change to Mn4+, which suppresses dissolution. |
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| Keywords: | lithium‐ion batteries cathodes lithium manganese oxide spinels graphenes density functional theory |
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