The property of MnO2 precursor has a great effect on the performance of LiMn2O4 product. In this study, Birnessite-type layered MnO2 was obtained through liquid phase coprecipitation reaction under neutral and acidic conditions. After heat treatment, the final product synthesized from MnO2 under neutral condition possesses the impurity phase MnO2 without any carbon layer, while the product synthesized from MnO2 under acidic condition is proved to be pure spinel LiMn2O4 with a thin carbon layer. The latter carbon-coated LiMn2O4 delivers the initial discharge capacity of 129.7 mAh/g at 0.2C, which is higher than that of the former product with only 58.5 mAh/g; even at higher rate of 30C, the discharge capacity can reach 117.8 mAh/g and retain about 92% capacity after 1500 cycles. The results show that when precursor MnO2 is optimized under acidic condition, the as-synthesized spinel LiMn2O4 can exhibit superior high-rate capability and long-life cycling stability, proving to be a promising cathode material for market applications.