Electrolysis Process-Facilitated Engineering of Primary Particles of Cobalt-Free LiNiO₂ for Improved Electrochemical Performance

Abstract

The particle morphology of LiNiO 2 (LNO), the final product of Co-free high-Ni layered oxide cathode materials, must be engineered to prevent the degradation of electrochemical performance caused by the H2−H3 phase transition. Introducing a small amount of dopant oxides (Nb 2 O 5 as an example) during the electrolysis synthesis of the Ni(OH) 2 precursor facilitates the engineering of the primary particles of LNO, which is quick, simple, and inexpensive. In addition to the low concentration of Nb that entered the lattice structure, a combination of advanced characterizations indicates that the obtained LNO cathode material contains a high concentration of Nb in the primary particle boundaries in the form of lithium niobium oxide. This electrolysis method facilitated LNO (EMF-LNO) engineering successfully, reducing primary particle size and increasing particle packing density. Therefore, the EMF-LNO cathode material with engineered morphology exhibited increased mechanical strength and electrical contact, blocked electrolyte penetration during cycling, and reduced the H2−H3 phase transition effects.

Oriented Gradient Doping of Zirconium in Ni-Rich Cathode to Achieve Ultrahigh Stability and Rate Capability

“…Besides, the XPS results (Figure S16 ), 51 O 1s (M−O, ROLi, C�O, C−O, Li x PF y O 2 ), 52 F 1s (LiF, Li x PF y O 2 / Li x PF y ), 53 and P 2p (Li x PF y O 2 , Li x PF y ). 54,55 By fitting the XPS results, it can be indicated that the Zr gradient doping samples have a higher surface stability. After long cycling, the peak of M−O (529.4 eV) can be detected in the O 1s of 10Zr PFCG, while other samples do not show this peak, implying that the impurity on 10Zr PFCG is much less than that on 10Zr NFCG and bare FCG, which will decelerate the capacity degradation.…”