nz9b02302_si_001.pdf (1.13 MB)
Capacity Fading of Ni-Rich NCA Cathodes: Effect of Microcracking Extent
journal contribution
posted on 2019-11-19, 21:29 authored by Gyeong
Won Nam, Nam-Yung Park, Kang-Joon Park, Jihui Yang, Jun Liu, Chong S. Yoon, Yang-Kook SunNi-rich Li[Ni1–x–yCoxAly]O2 (NCA) cathodes (1 – x – y = 0.8, 0.88, and 0.95) are synthesized
to investigate
the capacity fading mechanism of Ni-rich NCA cathodes. The capacity
retention and thermal property of the cathodes deteriorate as their
discharge capacity increases when the Ni fraction is increased. The
capacity fading correlates well with the anisotropic volume variations
caused by the H2–H3 phase transition and the resulting extent
of microcracking. Although all three cathodes start to develop microcracks
after being charged to 3.9 V, the potential at which microcracks propagated
to the outer surface of the particle decreases with increasing Ni
content. These microcracks undermine the mechanical integrity of the
cathode and facilitate electrolyte penetration into the particle core,
which accelerates surface degradation of the internal primary particles.
Therefore, mitigating or delaying the H2–H3 phase transition
is key to improving the cycling performance of Ni-rich NCA cathodes.