Low-Strain Reticular Sodium Manganese Oxide as an Ultrastable Cathode for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are recognized as attractive alternatives for grid-scale electrochemical energy storage applications. Transition metal oxide cathodes represent one of the most dynamic materials for industrialization among the various cathodes for SIBs. Here, a cation-doped cathode Na0.44Mn0.89Ti0.11O2 with a tunnel structure is introduced, which undergoes a lowered volume change of only 5.26% during the Na+ insertion/extraction process. Moreover, the average Na+ diffusion coefficients are enhanced by more than 3-fold upon the doping of the Ti cation. The obtained cathode delivers a practically usable capacity of 119 mAh g-1 at 0.1 C as well as an enhanced discharge capacity of 96 mAh g-1 at 5 C. Durability is demonstrated by the retained 71 mAh g-1 after 1000 cycles, corresponding to a capacity retention of 74%. This work demonstrates that the reticular Na0.44Mn0.89Ti0.11O2 is a promising ultrastable cathode material for the development of long-life sodium-ion batteries.