The structure-activity relationship between precursor fine structure and cathode performance in ultra-high Ni layered oxide

• The precursor secondary nucleation can be inhibited by combining radial stirring. • Inhibiting precursor secondary nucleation can increase the primary particle size. • The primary particles sizes with 675 nm display the best cycle life. The primary particle of ultra-high Ni cathodes is the direct carrier of Li + ions (de)intercalation, which greatly affects in the electrochemical performance. It should be noted that the primary particle geometry is an important parameter of cathode. However, the relationship between primary particle size and structural stability remains the lack of understanding. Herein, we investigated the impact of primary particle geometries in different size systems including 336, 447 and 565 nm (secondary particle size: ∼14 μm). The results demonstrated that larger cathode’s primary particle size can effectively alleviate localized stress to inhibit intragranular/intergranular cracks, simultaneously, which can also restrain the growth of CEI film, and relieve the structure decay. Moreover, the regulated cathode with the primary (secondary) particle size of 675 nm (∼6 μm) has better structural stability, indicating the cathodes with the larger primary particles and smaller secondary particles is the development tendency in the future.