Micro-spherical particle of MnCO3 has been successfully synthesized in CTAB–C8H18–C4H9OH–H2O micro-emulsion system. Mn2O3 decomposed from the MnCO3 is mixed with Li2CO3 and sintered at 800°C for 12h, and the pure spinel LiMn2O4 in sub-micrometer size is obtained. The LiMn2O4 has initial discharge specific capacity of 124mAhg−1 at discharge current of 120mAg−1 between 3 and 4.2V, and retains 118mAhg−1 after 110 cycles. High-rate capability test shows that even at a current density of 16C, capacity about 103mAhg−1 is delivered, whose power is 57 times of that at 0.2C. The capacity loss rate at 55°C is 0.27% per cycle.