Dual-Carbon confinement strategy of antimony anode material enabling advanced potassium ion storage

Antimony (Sb) has attracted considerable attention as an anode material for potassium ion batteries (PIBs) because of its high theoretical capacity. Nevertheless, owing to the large radius of K⁺, apparent volume expansion occurs during the reaction between Sb and K⁺, which will undermine the stability of the electrode. Accordingly, a dual-carbon confinement strategy is regarded as an effective method for handling this issue. Herein, Sb is firstly captured by mesoporous carbon sphere (MCS) to form a composite of Sb/MCS, and then reduced graphene oxide (rGO) is adopted as an outer layer to wrap the Sb/MCS to obtain the dual-carbon confinement material (Sb/MCS@rGO). Given the synergistic confinement effects of the MCS and rGO, the Sb/MCS@rGO electrode realizes an excellent rate capacity of 341.9 mAh g^-1 at 1000 mA g^-1 and prominent cycling stability with around 100% retention at 50 mA g^-1 after 100 cycles. Besides, the discussion on galvanostatic charge-discharge test, cyclic voltammetry and ex-situ XRD illustrates the stepwise potassium storage mechanism of Sb. Benefiting from the dual-carbon confinement effects, the Sb/MCS@rGO electrode processes promising electrochemical reaction kinetics. Furthermore, the application of the Sb/MCS@rGO in full cells also demonstrates its superior rate capacity (212.3 mAh g^-1 at 1000 mA g^-1).