Exposing {010} Active Facets in P2‐type Na 2/3 Ni 1/3 Mn 2/3 O 2 Cathode Material with Excellent Ultrahigh‐Rate Performance for Sodium‐Ion Batteries

Abstract P2‐type Na 2/3 Ni 1/3 Mn 2/3 O 2 is one of the most promising cathode materials for Na‐ion batteries (SIBs) due to its robust air stability and high operating voltage. Nevertheless, Na 2/3 Ni 1/3 Mn 2/3 O 2 suffers an inferior rate performance caused by the low Na + diffusion kinetics and poor structural stability. Hence, this study designed a novel porous P2‐type Na 2/3 Ni 1/3 Mn 2/3 O 2 cathode material with abundant active {010} crystal faces, which is synthesized by regulating the growth rate of the precursor and its discontinuous shrinkage during the sintering process. It is found that the exposed active {010} crystal faces can accelerate the transmission of Na + ions and alleviate the stress accumulation inside the material under ultrahigh‐rate charging and discharging, maintaining the integrity of the material during the cycling process. Therefore, the porous material exhibits excellent ultrahigh‐rate discharge capability. It can maintain a capacity retention of 77.5% at 25 C compared to 1 C. Even after 400 cycles at 5 C, the capacity retention reaches 83.4%, which is much higher than that of materials lacking active crystal faces (72.28%). Such a feasible and effective strategy may develop a new path toward the rational design of excellent rate capability and long cycle stability cathode materials for SIBs.