Two-position intrinsic element complement: Synthesis and electrochemical properties of Li2+ xMn1-xSiO4@carbon as cathode materials for lithium batteries

Li2 + xMn1-xSiO4 compounds with a deficiency and an excess of lithium as a cathode material for Li-ion batteries were synthesized by the solid-state synthesis method, and a two-step calcination process was applied to improve the electrochemical properties. The calcination temperature was determined by the thermogravimetric analysis and differential scanning calorimetry (TG-DSC) curves. The synthesized compounds were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and other material testing methods. A MnO and Mn2SiO4 impurity was detected in the Li2 + xMn1-xSiO4 compounds. The cycle performance of Li1.96Mn1.04SiO4, Li1.98Mn1.02SiO4, and Li2.02Mn0.98SiO4 cathode materials for lithium-ion batteries was tested to compare with that of pure Li2MnSiO4. The Li2.02Mn0.98SiO4 sample doped with an excess of Li both has a high first discharge specific capacity and excellent electrochemical cycle stability. The introduction of an appropriate strategy to produce a lithium excess is an effective way to improve the electrochemical performance of cathode materials.