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

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.