Nowadays lithium-ion batteries (LIBs) are widely used in nomad applications and electric vehicles. There are a lot of developments focused on electrode materials to improve the energy density. Lithium nickel manganese oxide (LMNO) is currently considered as one of the most promising cathode material for future 5 V lithium ion batteries. Nevertheless common electrolytes which are based on mixtures of alkylcarbonates containing LiPF₆ as salt are strongly oxidized at the LMNO cathode ^[1]. As a result, battery performances are very limited. To improve the high voltage tolerance of the electrolyte, various formulations have been developed. Electrolyte additives can affect the reactions of decomposition of the electrolyte leading to the formation of a protective passive layer on the surface of the active material. Succinic anhydride (SA) seems to have a beneficial effect in LMNO based cells, lowering significantly capacity losses (or enhance capacity retention) and improving battery cycling life and the coulombic efficiency ^[2]. However, the role of SA on electrode/electrolyte interfacial mechanisms isn’t fully understood in graphite/LMNO cells. In this communication, the influence of SA as electrolyte additive is studied in various type of cells (half, full or symmetrical cells) based on LMNO and graphite electrodes. Preliminary results showed that SA does not operate efficiently at 20°C in EC:EMC – LiPF₆1 M mixture (see figure 1) in Li/Gr and Gr/Gr symmetrical cells. This study is completed by identifying the nature of electrolyte degradation products formed upon cycling (GC-MS analysis) and characterizing the protective layer on the surface of electrodes (X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS)).

[1] J. Demeaux, E. De Vito, M. Le Digabel, H. Galiano, D. Lemordant and B. Claude-Montigny, ECS Transactions 2013, 53, 5-21.

[2] V. Tarnopolskiy, J. Kalhoff, M. Nádherná, D. Bresser, L. Picard, F. Fabre, M. Rey and S. Passerini, Journal of Power Sources 2013, 236, 39-46.