Sol-Gel Synthesis of Silicon-Doped Lithium Manganese Oxide with Enhanced Reversible Capacity and Cycling Stability

A series of silicon-doped lithium manganese oxides were obtained via a sol-gel process. XRD characterization results indicate that the silicon-doped samples retain the spinel structure of LiMn₂O₄. Electrochemical tests show that introducing silicon ions into the spinel structure can have a great effect on reversible capacity and cycling stability. When cycled at 0.5 C, the optimal Si-doped LiMn₂O₄ can exhibit a pretty high initial capacity of 140.8 mAh g^-1 with excellent retention of 91.1% after 100 cycles, which is higher than that of the LiMn₂O₄, LiMn_1.975Si_0.025O₄, and LiMn_1.925Si_0.075O₄ samples. Moreover, the optimal Si-doped LiMn₂O₄ can exhibit 88.3 mAh g^-1 with satisfactory cycling performance at 10 C. These satisfactory results are mainly contributed by the more regular and increased MnO₆ octahedra and even size distribution in the silicon-doped samples obtained by sol-gel technology.