Electrolyzed Ni(OH)₂ Precursor Sintered with LiOH/LiNiO₃ Mixed Salt for Structurally and Electrochemically Stable...

Cobalt-free LiNiO₂ cathode materials offer a higher energy density at a lower cost than high Co-containing cathode materials. However, Ni(OH)₂ precursors for LiNiO₂ cathodes are traditionally prepared by the coprecipitation method, which is expensive, complex, and time-consuming. Herein, we report a fast, facile, and inexpensive electrolysis process to prepare a Ni(OH)₂ precursor, which was mixed with LiOH/LiNO₃ salts to obtain a LiNiO₂ cathode material. A combination of advanced characterization techniques revealed that the LiNiO₂ cathode material prepared in this way exhibited an excellent layered structure with negligible Li/Ni site mixing and surface structural distortion. Electrochemical cycling of the LiNiO₂ cathode material showed an initial discharge capacity of 235.2 mA h/g and a capacity retention of 80.2% after 100 cycles (at 1 C) between 2.75 and 4.3 V. The degradation of the cycling performance of the LiNiO₂ cathode material was mainly attributed to the formation of a surface solid-electrolyte interface and a ∼5 nm rock salt-like structure, while the bulk structure of the cathode after cycling was generally stable.