title: High-energy cathode material for long-life and safe lithium batteries.
abstract: Layered lithium nickel-rich oxides, Li[Ni(1-x)M(x)]O(2) (M=metal), have attracted significant interest as the cathode material for rechargeable lithium batteries owing to their high capacity, excellent rate capability and low cost. However, their low thermal-abuse tolerance and poor cycle life, especially at elevated temperature, prohibit their use in practical batteries. Here, we report on a concentration-gradient cathode material for rechargeable lithium batteries based on a layered lithium nickel cobalt manganese oxide. In this material, each particle has a central bulk that is rich in Ni and a Mn-rich outer layer with decreasing Ni concentration and increasing Mn and Co concentrations as the surface is approached. The former provides high capacity, whereas the latter improves the thermal stability. A half cell using our concentration-gradient cathode material achieved a high capacity of 209 mA h g(-1) and retained 96% of this capacity after 50 charge-discharge cycles under an aggressive test profile (55 degrees C between 3.0 and 4.4 V). Our concentration-gradient material also showed superior performance in thermal-abuse tests compared with the bulk composition Li[Ni(0.8)Co(0.1)Mn(0.1)]O(2) used as reference. These results suggest that our cathode material could enable production of batteries that meet the demanding performance and safety requirements of plug-in hybrid electric vehicles.
authors.affiliation: Center for Information and Communication Material, Department of Chemical Engineering, Hanyang University, Seoul 133-791, South Korea. yksun@hanyang.ac.kr
authors.forename: Yang-Kook
authors.initials: YK
authors.lastname: Sun
authors.forename: Seung-Taek
authors.initials: ST
authors.lastname: Myung
authors.forename: Byung-Chun
authors.initials: BC
authors.lastname: Park
authors.forename: Jai
authors.initials: J
authors.lastname: Prakash
authors.forename: Ilias
authors.initials: I
authors.lastname: Belharouak
authors.forename: Khalil
authors.initials: K
authors.lastname: Amine