The large volume expansion of FeS2 is successfully accommodated via a series of asynchronous redox reactions of dual-crystalline FeS2. Consequently, a durable sodium storage performance with a reversible capacity of 567.7 mA h g-1 is obtained at 0.1 A g-1 after 50 cycles. This novel strategy can also be utilized in other types of electrodes having large volume change upon cycling.