title: Understanding the Degradation Mechanism of Lithium Nickel Oxide Cathodes for Li-Ion Batteries.
abstract: The phase transition, charge compensation, and local chemical environment of Ni in LiNiO2were investigated to understand the degradation mechanism. The electrode was subjected to a variety of bulk and surface-sensitive characterization techniques under different charge-discharge cycling conditions. We observed the phase transition from the original hexagonal H1 phase to another two hexagonal phases (H2 and H3) upon Li deintercalation. Moreover, the gradual loss of H3-phase features was revealed during the repeated charges. The reduction in Ni redox activity occurred at both the charge and the discharge states, and it appeared both in the bulk and at the surface over the extended cycles. The degradation of crystal structure significantly contributes to the reduction of Ni redox activity, which in turn causes the cycling performance decay of LiNiO2.
authors: Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors: Jing
authors: J
authors: Xu
authors: Enyuan
authors: E
authors: Hu
authors: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors: Dennis
authors: D
authors: Nordlund
authors: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors: Apurva
authors: A
authors: Mehta
authors: Steven N
authors: SN
authors: Ehrlich
authors: Xiao-Qing
authors: XQ
authors: Yang
authors: Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors: Wei
authors: W
authors: Tong
keywords: Li-ion batteries; Ni-rich layered oxide cathode; capacity fade; phase evolution; redox reaction; surface characteristics