Key points are not available for this paper at this time.
Abstract In the quest to elevate the sodium‐ion intercalation kinetics of transition metal oxide electrodes, the intrinsic low conductivity of these materials often acts as a bottleneck, restricting Na + storage. Herein, the mechanism behind sodium‐ion diffusion kinetics in MnO 2 is explored, specifically focusing on the manipulation of π * antibonding orbital occupancy. This is accomplished through strategic doping with strongly electron‐withdrawing Rh 3+ ( t 2g 6 e g 0 ), enhancing the hybridization of Mn 3 d ‐O 2 p orbitals and significantly increasing the electrical conductivity of MnO 2 . Density functional theory (DFT) calculations and X‐ray absorption spectroscopy (XAS) results demonstrate that the smaller orbital energy difference between Rh 3+ e g and Mn 4+ t 2g , compared to that between Rh 3+ e g and Mn 4+ e g , fosters direct electron transfer from the Mn 4+ t 2g to the vacant Rh 3+ e g . This electron movement induces an upshift in the Mn‐ t 2g orbital energy levels while concurrently diminishing the occupancy of π * antibonding orbitals formed via Mn t 2g ‐O 2 p hybridization. The resultant Rh‐MnO 2 electrode exhibits an impressive specific capacity of 335 F g −1 at 1 A g −1 and a substantial rate capacity of 224.8 F g −1 at 20 A g −1 . This investigation elucidates the intricate mechanism underlying the sluggish kinetics of sodium ion intercalation within transition metal oxide frameworks.
Wang et al. (Fri,) studied this question.