Current research efforts in lithium batteries are directed towards achieving higher energy density at a reduced cost and increased safety and cycle life performance.1 Lithium-ion electrodes based on single charge transfer intercalation mechanism exhibit stable reversible capacity and cycle life but their specific capacities range only between 150-180 mAh/g.2 Over the last decade there has been intense research activity of high voltage (and capacity) cathodes for Li-ion. Most prominently among them include lithium-manganese rich cathodes (LMR-NMC) and high voltage spinels. LMR-NMC compositions commonly denoted by Li1+xMnyNizCo1-x-y-zO2 or xLi2MnO3. (1-x)LiMO2 (M = Mn, Ni and Co) with x=0.2-0.6 promise a capacity in the range of 280-300 mAh/g when cycled up to 4.8V.3 Nevertheless, these classes of materials have a number of materials challenges that limits their use for heavy duty automotive application. Recent studies have shown that upon extended cycling to higher voltages, the electrochemical voltage profile gradually shifts to lower voltages causing loss in energy and structural instability commonly referred to as “voltage fade”.4,5 The talk will discuss a number of approaches to stabilize the cathode structure and improve their interfacial stability. These include, coating the cathode surface using a nanometer layer solid electrolyte coating, using electrolyte additives and/or limiting the operating electrochemical window. In the following part of the talk, focus will be on applying various x-ray and electron microscopy methods to understand the origin of the structural instability and voltage fade in such high voltage cathode systems. Finally we will present some of our recent efforts on high capacity 2-lithium systems based on Cu-Ni system. This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy. (1) Tarascon, J. M.; Armand, M. Nature 2001, 414, 359. (2) Whittingham, M. S. Chem. Rev. 2004, 104, 4271. (3) Thackeray, M. M.; Kang, S. H.; Johnson, C. S.; Vaughey, J. T.; Benedek, R.; Hackney, S. A. J. Mater. Chem. 2007, 17, 3112. (4) Bettge, M.; Li, Y.; Gallagher, K.; Zhu, Y.; Wu, Q. L.; Lu, W. Q.; Bloom, I.; Abraham, D. P. J. Electrochem. Soc. 2013, 160, A2046. (5) Yang, F.; Liu, Y.; Martha, S. K.; Wu, Z.; Andrews, J. C.; Ice, G. E.; Pianetta, P.; Nanda, J. Nano Lett. 2014, 14, 4334.

High voltage cathodes for advanced lithium-ion batteries

249th National Meeting (2015)

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