Nanostructured high-energy cathode materials for advanced lithium batteries

Nickel-rich layered lithium transition-metal oxides, LiNi1?xMxO2 (M?=?transition metal), have been under intense investigation as high-energy cathode materials for rechargeable lithium batteries because of their high specific capacity and relatively low cost. However, the commercial deployment of nickel-rich oxides has been severely hindered by their intrinsic poor thermal stability at the fully charged state and insufficient cycle life, especially at elevated temperatures. Here, we report a nickel-rich lithium transition-metal oxide with a very high capacity (215?mA?h?g?1), where the nickel concentration decreases linearly whereas the manganese concentration increases linearly from the centre to the outer layer of each particle. Using this nano-functional full-gradient approach, we are able to harness the high energy density of the nickel-rich core and the high thermal stability and long life of the manganese-rich outer layers. Moreover, the micrometre-size secondary particles of this cathode material are composed of aligned needle-like nanosize primary particles, resulting in a high rate capability. The experimental results suggest that this nano-functional full-gradient cathode material is promising for applications that require high energy, long calendar life and excellent abuse tolerance such as electric vehicles.This work was supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 20114010203150) and the National Research Foundation of KOREA (NRF) grant funded by the Korea government (MEST; No. 2009-0092780). Research at Argonne National Laboratory was funded by the US Department of Energy, EERE Vehicle Technologies Program. Argonne National Laboratory is operated for the US Department of Energy by UChicago Argonne, LLC, under contract DE-AC02-06CH11357. The authors also acknowledge the use of the Advanced Photon Source of Argonne National Laboratory supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences