Simultaneous Component Ratio and Particle Size Optimization for High‐Performance and High Tap Density P2/P3 Composite Cathode of Sodium‐Ion Batteries

Abstract The composite structure materials in sodium‐ion batteries (SIBs) have received increasing attentions due to the synergistic effect. P2/P3 composite cathode with the advantages of high reversible capacity and superior reaction kinetics was regarded as one of the promising cathodes for SIBs. Crystal phase component ratio and particle morphology of hybrid structures are closely related with the electrochemical performance, especially the energy density. Herein, P2/P3 hybrid structure materials Na 0.6 Mn 1‐ x Ni x O 2 were synthesized by co‐precipitation method. Furthermore, the component ratio and particle size are tuned and realized via simple Ni 2+ content optimization. The targeted sample Na 0.6 Mn 0.75 Ni 0.25 O 2 shows high tap density over 1.2 g cm −3 and excellent electrical properties with an initial capacity of 101.36 mA h g −1 at 0.2 C, corresponding to a high volumetric energy density of 512 Wh L −1 based on the cathode active material. Moreover, the long‐term cycling capacity retention can reach 68 % at 1 C after 500 cycles. The present study develops a promising cathode of SIBs that maybe applied in low‐speed electric vehicles. And the simultaneous optimization design represents a potential route for the regulation of composite structures to obtain high performance SIBs.