Coupled Adsorption–Catalysis at V ₂ O ₃ /Carbon Interface to Accelerate Polyselenides Conversion and Suppress Shuttling in Sodium–Selenium Batteries

Abstract

Abstract Sodium‐selenium (Na‐Se) batteries offer high theoretical energy density at low cost. However, their practical application is limited by sluggish redox kinetics and the polyselenides (Na 2 Se x ) shuttle effect, resulting in poor cycling stability. In this study, a pomegranate‐like hierarchical “seed‐aril” composite structure (V 2 O 3 @Se/C) is synthesized via a facile one‐step hydrothermal method followed by thermal annealing. In this architecture, selenium nanospheres are initially encapsulated by V 2 O 3 and subsequently embedded within a porous C matrix. During electrochemical cycling, V 2 O 3 provides strong chemisorption and catalytic activity toward Na 2 Se x intermediates, promoting their reduction to Na 2 Se and facilitating nucleation. The subsequently generated Na 2 Se x are further captured and catalyzed by V 2 O 3 , sustaining redox activity. Simultaneously, the porous C framework physically adsorbs and spatially confines uncatalyzed Na 2 Se x while synergistically enhancing the catalytic effectiveness of V 2 O 3 and providing electronic pathways, thereby promoting the conversion of long‐chain Na 2 Se x to short‐chain species. V 2 O 3 @Se/C cathode delivers a high specific capacity of 670.3 mAh g −1 at 0.1 A g −1 and retains 362 mAh g −1 at 10 A g −1 . Remarkably, at an ultrahigh current density of 30 A g −1 , it maintains a reversible capacity of 310 mAh g −1 after 2500 cycles, corresponding to an ultralow capacity fading rate of 0.00063% per cycle.