Synthesis and characterization of Li2MnO2F as cathodes for Li-ion batteries

BRACAMONTE M. V; DOLINAR, PIA; ATEBA MBA, JEAN MARCEL; TCHERNYCHVA, E; PARAPARI, S.; RUIZ-ZEPEDA, F; MALI, G; JERMAN, I. ; DOMINKO, R

Vittoria Gazteiz

Congreso; Power Our Future 2019; 2019

CIC Energigune

As a significant component of lithium-ion batteries (LIBs), cathode plays a key role in determining electrochemical and safety performance.1 Thus, cathode materials with unique properties, such as high capacity, good cyclability and environmental compatibility, have become one of the focuses for improving the performances of current batteries.2 Among various cathode materials, manganese based oxides are promising alternatives due to the high voltage range (∼2.5?4.2 V) achievable by the Mn3+/Mn4+ redox couple. However, most of the studied structures consist in ordered phases, such as o-LiMnO2 or Li2MnO3 which can suffer a fast capacity fade due to Mn2+ dissolution in the electrolyte during cycling 3 and/or the Jahn-Teller effect of the Mn3+ ion.4 For this reason, there has been increasing interest in disordered intercalation compounds. In particular, it has been proved that disordered rocksalt structures can provide the sufficient lithium/transition metal ratio to permit enough low energy percolation pathways,5,6 functioning as promising intercalation compounds with relatively high capacities. Also different strategies, as surface coating and bulk doping, have been used to improve the electrochemical performance of these materials. Related with doping, has been demonstrated that small incorporation of F in the structure could reduce Mn dissolution (from hydrogen fluoride attack) and enhance the cyclability.7,8 The incorporation of fluorine anions (F-) can simultaneously enhanced the C-rate capability and capacity fading.In this work, we propose an alternative synthesis route of an all-manganese lithium transition metal oxyfluoride, with a disordered rock-salt structure based on ceramic method. We used different synthesis routes to achieve the desired structure and we fully characterize the obtained samples using XRD, SEM, Raman, TEM, 6,7Li and 19F NMR and ICP-MS. The systematic characterization of the samples allows us to get a better understanding (and correlation) between the structural features with the electrochemical performance of these materials as cathodes for Li batteries.References:1Z. Yang, J. Zhang, M. C. W. Kintner-Meyer, X. Lu, D. Choi, J. P. Lemmon and J. Liu, Chemical Reviews, 2011, 111, 3577?3613.2S. Zhou, G. Wang, W. Tang, Y. Xiao and K. Yan, Electrochimica Acta, 2018, 261, 565?577.3D. H. Jang, Y. J. Shin and S. M. Oh, Journal of The Electrochemical Society , 1996, 143, 2204?2211.4A. Yamada, Journal of Solid State Chemistry, 1996, 122, 160?165.5J. Lee, D.-H. Seo, M. Balasubramanian, N. Twu, X. Li and G. Ceder, Energy & Environmental Science, 2015, 8, 3255?3265.6T. Sato, K. Sato, W. Zhao, Y. Kajiya and N. Yabuuchi, 2018, 13943?13951.7R. A. House, L. Jin, U. Maitra, K. Tsuruta, J. W. Somerville, D. P. Förstermann, F. Massel, L. Duda, M. R. Roberts and P. G. Bruce, Energy & Environmental Science, 2018, 11, 926?932.8W. D. Richards, S. T. Dacek, D. A. Kitchaev and G. Ceder, 2017, 1701533, 1?7.