O3-type layer-structured Na-0(.8)[Ni1/5Fe1/5Co1/5Mn1/5Ti1/5]O-2 as long life and high power cathode material for sodium-ion batteries

Abstract

O3-type layer-structured Na-0(.8)[Ni1/5Fe1/5Co1/5Mn1/5Ti1/5]O-2 (denoted as N0.8NFCMTO) has been investigation as a new cathode material for Na-ion batteries. The N0.8NFCMTO cathode delivers an initial discharge capacity of 107 mAhg(-1) with excellent cycling stability of over 90% capacity retention after 100 cycles. This mater delivers comparable capacity to that of previously reported layered cathode materials with multi-transition metal elements while showing an excellent rate capability and stable long cycle life. Synchrotron-based in situ ray diffraction and ex situ X-ray absorption spectroscopy investigations combined with quantitative refinement analysis reveal the reversible structural changes and charge compensation mechanism during sodium extraction insertion, which is associated with the excellent cycling stability of the N0.8NECMTO electrode.