Dynamic in-situ reconstruction of soft-rigid Fe₃Se₄/MnSe heterostructures: self-adaptive interfaces and d-band center...

Volume expansion and interfacial instability in transition metal selenides limit the realization of their high theoretical capacity in lithium/sodium-ion batteries (LIBs, SIBs). This work reports an in-situ electrochemical reaction-triggered structural evolution that transforms Fe₃Se₄/MnSe heterostructures encapsulated in N, Se co-doped hollow carbon nanospheres into soft-rigid components. This approach breaks away from conventional static electrode designs by introducing a dynamic in-situ reconstruction strategy. Through atomically precise electronic regulation and multi-scale structural engineering, it effectively overcomes inherent limitations. Specifically, the material undergoes a unique "tailored phase transformation": Fe₃Se₄ transforms into an amorphous structure, acting as a soft component to ensure rapid ion dynamics; meanwhile MnSe transforms from the α-phase to the β-phase with high degree of crystallinity, serving as a mechanical stabilizer to withstand volume strain. Furthermore, density functional theory calculations indicate that this heterostructure achieves an optimized d-band center (-0.277 eV), which acts as an electron regulator to enhance interfacial chemical bonding while simultaneously lowering the activation energy barrier for ion insertion/extraction. Consequently, the anode exhibits outstanding electrochemical properties: under the current density of 2 A g^-1 maintaining a capacity of 714 mAh g^-1 for LIBs and 252 mAh g^-1 for SIBs after 1500 cycles.