Delivery of high capacity with good retention is a challenge in developing cathodes for rechargeable sodium-ion batteries. Here we present a radially aligned hierarchical columnar structure in spherical particles with varied chemical composition from the inner end (Na[Ni<inf>0.75</inf>Co<inf>0.02</inf>Mn<inf>0.23</inf>]O<inf>2</inf>) to the outer end (Na[Ni<inf>0.58</inf>Co<inf>0.06</inf>Mn<inf>0.36</inf>]O<inf>2</inf>) of the structure. With this cathode material, we show that an electrochemical reaction based on Ni<sup>2+/3+/4+</sup> is readily available to deliver a discharge capacity of 157 mAh (g-oxide)<sup>-1</sup> (15mAg<sup>-1</sup>), a capacity retention of 80% (125mAhg<sup>-1</sup>) during 300 cycles in combination with a hard carbon anode, and a rate capability of 132.6 mAhg<sup>-1</sup> (1,500mAg<sup>-1</sup>, 10 C-rate). The cathode also exhibits good temperature performance even at -20°C. These results originate from rather unique chemistry of the cathode material, which enables the Ni redox reaction and minimizes the surface area contacting corrosive electrolyte.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)