Sodium-ion
batteries (SIBs) have been extensively studied owing
to the abundance and low-price of Na resources. However, the infeasibility
of graphite and silicon electrodes in sodium-ion storage makes it
urgent to develop high-performance anode materials. Herein, α-MnSe
nanorods derived from δ-MnO2 (δ−α-MnSe)
are constructed as anodes for SIBs. It is verified that α-MnSe
will be transferred into β-MnSe after the initial Na-ion insertion/extraction,
and δ−α-MnSe undergoes typical conversion mechanism
using a Mn-ion for charge compensation in the subsequent charge–discharge
process. First-principles calculations support that Na-ion migration
in defect-free α-MnSe can drive the lattice distortion to phase
transition (alpha → beta) in thermodynamics and dynamics. The
formed β-MnSe with robust lattice structure and small Na-ion
diffusion barrier boosts great structure stability and electrochemical
kinetics. Hence, the δ−α-MnSe electrode contributes
excellent rate capability and superior cyclic stability with long
lifespan over 1000 cycles and low decay rate of 0.0267% per cycle.
Na-ion full batteries with a high energy density of 281.2 Wh·kg–1 and outstanding cyclability demonstrate the applicability
of δ−α-MnSe anode.