A special acanthosphere shaped FeCO3 anode powder material was synthesized successfully through controlled hydrothermal method. It delivered an initial specific discharge-charge capacity of 2100/1087mAhg−1 at a current density of 100mAg−1, and exhibited a high discharge capacity of 238mAhg−1 even at a current of 10,000mAg−1. Furthermore, its capacity would return to the initial capacity level even if the discharge/charge current got back from 10,000mAg−1 to 100mAg−1. Galvanostatic intermittent titration technique (GITT) method was used to investigate the lithiation mechanism of FeCO3 electrode, and results showed that the lithium ion diffusion was driven by two step reactions, the first transition from FeCO3 to Fe and the second reduction of newly grated LiCO3, respectively. High diffusion coefficients of Li ions also give the reason for the high capacity under large rate charge-discharge condition.