Nonflammable Sulfone-Based Electrolytes for Achieving High-Voltage Li-Ion Batteries Using LiNi 0.5 Mn 1.5 O 4 Cathode Material

High voltage Li-ion batteries have been expected a forward technology designed for vehicles, marines and other high power and energy density applications 1–3 . Among high voltage cathodes, LiNi 0.5 Mn 1.5 O 4 is considered a promising cathode to reduce the battery cost as well as environmental hazard issues 4,5 . However, a high operation potential and Mn dissolution brings the most critical challenges for achieving the long cycle-life of Li-ion cell 6,7 . In this study, we report a rational design of nonflammable electrolyte based on LiBF 4 and sulfolane (TMS) mixed with a dimethyl carbonate (DMC) as co-solvent to enhance conductivity. Among different molar ratios, the electrolyte LiBF 4 : TMS: DMC =1:2:1 in mol. exhibited the highest electrochemical stability (~ 6.1 V vs. Li + /Li) and ionic conductivity up to 1.57 mS.cm -1 at 30 o C. Cycling performance of LNMO/Li half-cell and LNMO/graphite full-cell cycled were carried out using the optimized electrolyte. While half-cells LNMO//Li display a high initial capacity of 118 mAh.g -1 and remain 56.48 % of initial value after 100 cycles, a full cell LNMO//Graphite with an areal loading of 1.0 mAh.cm -2 and low N/P ratio (~1.2) exhibited a better cycling stability than the one using commercial electrolyte 1M LiPF 6 /EC-DMC, 1:1 in vol (with initial capacity of 87 mAh.g -1 and capacity retention of 18% after 100 cycles 8 ). References Goodenough JB, Kim Y. Challenges for Rechargeable Li Batteries. Chem Mater . 2010;22(3):587-603. Etacheri V, Marom R, Elazari R, Salitra G, Aurbach D. Challenges in the development of advanced Li-ion batteries: a review. Energy Environ Sci . 2011;4(9):3243. Amine K, Kanno R, Tzeng Y. Rechargeable lithium batteries and beyond: Progress, challenges, and future directions. MRS Bull . 2014;39(5):395-401. Kim J-H, Myung S-T, Sun Y-K. Molten salt synthesis of LiNi 0.5 Mn 1.5 O 4 spinel for 5 V class cathode material of Li-ion secondary battery. Electrochim Acta . 2004;49(2):219-227. Patoux S, Daniel L, Bourbon C. High voltage spinel oxides for Li-ion batteries: From the material research to the application. J Power Sources . 2009;189(1):344-352. Jang DH, Shin YJ, Oh SM. Dissolution of Spinel Oxides and Capacity Losses in 4 V Li / Li x Mn 2 O 4 Cells. J Electrochem Soc . 1996;143(7):2204-2211. Du Pasquier A, Blyr A, Courjal P. Mechanism for Limited 55°C Storage Performance of Li 1.05 Mn 1.95 O 4 Electrodes. J Electrochem Soc . 1999;146(2):428-436. Wang J, Yamada Y, Sodeyama K, Chiang CH