Electrolyzed Ni(OH)2 Precursor Sintered with LiOH/LiNiO3 Mixed Salt for Structurally and Electrochemically Stable Cobalt-Free LiNiO2 Cathode Materials.

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.